Restorative/DMS/ General

Question 1

Endodontic stainless steel mishapes

Answer 1

Ledges
blockage
perforations
transportation of apical foramen/Apical zipping

Question 2

What are ledges?

Answer 2

ledges are internal transportation of the root canal that may be due to wrong working length or skipping file sizes

Question 3

What is a blockage?

Answer 3

Apical blockage of the canal due to dentin chips, tissue debris of calcification of the canal

Question 4

What are perforations?

Answer 4

communication between canal walls and periodontal space

Question 5

How does transportation of apical foramen occurs?

Answer 5

it occurs as a result of the tendency of a the file to straighten up in a curved canal resulting in transportation of the apical foramen

Question 6

Write the endodontic treatment up to obturation

Answer 6

• Acccess the coronal part of the tooth after taking pre-op PA and placing rubber dam and LA
• Remove any caries, locate canal orifices and create an isolated environment
• Prepare, irrigate and instrument root canals using protaper technique
• Obturate with GP,, assess restorability and seal
• provide final restoration

Question 7

What are the consistuents of gutta percha?

Answer 7

20% GP
65% zinc oxide
10% radiopacifiers
5% plasticisers

Question 8

What are the disadvantages of cold lateral compaction?

Answer 8

voids
incomplete fusion of GP cones
lack of surface adaptation

Question 9

What are the disadvantages in using sized matched cones for endo obturation?

Answer 9

• it leaves very little space for accessory cones

Question 10

What are the three thermal techniques used in obturation?

Answer 10

• warm vertical compaction
• continuous wave obturation
• carrier based obturation

Question 11

What are the function of RCT sealers

Answer 11

Seal the space between dentinal wall and core
Fills voids and irregularities in canal
lubricates during obturation

Question 12

What are the ideal properties of canal sealers?

Answer 12

good adhesion
easily mixed
slow set
no shrinkage on setting
non staining

Question 13

What materials are used in sealers?

Answer 13

Zinc oxide eugenol based
GI
Resin sealers (epoxy)
Calcium silicate sealers

Question 14

What are the advantages and disadvantages of zinc oxide?

Answer 14

• Advantages : antimicrobial and cytoprotection
• Disadvantages : soluble with time and irritant

Question 15

What are the properties of glass ionomer as a sealer material?

Answer 15

• Dentine bonding properties
• minimal antimicrobial activity and greater solubility

Question 16

What are the properties of calcium silicate sealers?

Answer 16

• does not shrink on setting
• non resorbable
• quick set (may require moisture)
• easy to use

Question 17

What are the properties of resin sealers?

Answer 17

• good sealing ability
• good flow
• toxicity declines after 24h
• good penetration into tubules
• biocompatible

Question 18

What to check in post op radiograph (RCT)

Answer 18

• length
• taper
• density
• GP removal at canal orifices and to facial CEJ
• any obturation errors

Question 19

What to use to close canal orifices?

Answer 19

RMGI
flowable composite
Zinc oxide eugenol

Question 20

What are the benefits of copper enriched amalgam?

Answer 20

• high early strength
• high corrosion resistance
• high durability of margins
• less creep

Question 21

What is the function of zinc in amalgam?

Answer 21

• acts as an oxygen scavenger molecule and form slag

This prevents the oxidation of other metals in the amalgam alloy (such as tin and copper), which can otherwise weaken the final product.

Question 22

How is copper enriched amalgam made?

Answer 22

By mixing silver copper eutectic particles with silver tin lathe cut particles to produce high copper y-2 free amalgam

Question 23

Explain the process of delayed expansion in amalgam?

Answer 23

• alloys containing zinc when contaminated with moisture during condensation lead to expansion due to the release of hydrogen

This may cause internal pressure leading to pulp irritation

It can also cause high occlusal points leading to interference of occlusion and fracture

Question 24

What is creep?

Answer 24

Creep is the slow
stressing and deformation of amalgam due to continuous low stress levels over a long period of time

Question 25

What are the symptoms of amalgam creep?

Answer 25

• ditching of margins > microleakage > secondary caries
• Microleakage can cause pulpal irritation, secondary caries and discooration under the restoration

Question 26

What areas in the upper and lower that give support in upper and lower complete dentures?

Answer 26

Upper = hard palate, maxillary tuberosity and residual ridge (secondary)
Lower = Retromolar pad, buccal shelf and residual ridge (secondary)

Question 27

What provides support in partial dentures?

Answer 27

Rests (occlusal and cingulum)

Question 28

What is kennedy classification?

Answer 28

anatomical classification that describes the number and distribution of edentulous areas present

Question 29

What is kennedy class 1

Answer 29

bilateral free end saddle

Question 30

What is Kennedy classification 2?

Answer 30

Unilateral free end saddle

Question 31

What is kennedy classification 3

Answer 31

bounded saddle

Question 32

What is kennedy class 4 ?

Answer 32

anterior bounded saddle crossing the midline

Question 33

What does the palatal extension provide?

Answer 33

It provides increased mucosal support as a larger surface area is covered which can create a greater seal

Question 34

Why do we place rest seats on anterior teeth?

Answer 34

it can provides indirect retention and bracing

Question 35

why do we place rest seats on posterior teeth?

Answer 35

To offer support to the RPD preventing it from moving towards the mucosa , it can also aid in indirect retention and reciprocation

Question 36

What is bracing in partial dentures?

Answer 36

Provides horizontal stabilization against lateral forces, ensuring the denture does not shift sideways during function.

Question 37

How can bracing be achieved?

Answer 37

• minor connectors
• major connectors
• bracing arms

Question 38

What are the different types of clasps for pre-molars?

Answer 38

• gingivally approaching I bar clasp
• modified t clasp
• circumferential clasp

Question 39

What are the different types of clasps for molars?

Answer 39

Occlusally approaching single are clasp
Occlusally approaching circumferential clasp
Occlusally approaching ring clasp

Question 40

Why is it beneficial to keep the gingival margin clear by not extending a partial denture framework to the anteriors?

Answer 40

• less mucosal coverage
• easier to clean gingival tissues
• less irritation
• better compliance

Question 41

What impression materials are used for primary impressions in complete dentures?

Answer 41

• impression compound - non elastic
• alginate - elastic irreversible hydrocholloid

Question 42

What are the consistuents of alginate?

Answer 42

• calcium sulphate
• Sodium alginate
• sodium phosphate
• trisodium phosphate
• flavouring
• filler particles
• salt and algenic acid

Question 43

What are the consistuents of green stick?

Answer 43

• rosin
• carnauba wax
• talc
• stearic acid

Question 44

Why place impression compound on a tooth?

Answer 44

• to record a single tooth crown preparation

Question 45

What technique is used to record a single crown prep?

Answer 45

copper ring technique using impression compound

Question 46

What is the procedure of the copper ring technique?

Answer 46

• select copper ring
• check it seats well around the tooth and it should extend to the gingival margin
• Fill the ring with impression compound and place around the tooth

Question 47

What are the advantages of the copper ring technique?

Answer 47

• simple
• capture details accurately

Question 48

How to manage GP that is exposed for more than 3 months?

Answer 48

• it requires re-root treatment as it is at risk of bacterial invasion

Question 49

What are the restorative options for a fractured 26 MOD amalgam which has been root treated?

Answer 49

• Onlay or inlay depends on the size of restoration and cuspal coverage
• Crown (MCC)
• place another amalgam restoration

Question 50

What is Nayyar core?

Answer 50

• amalgam acting as a core extending 3-4mm into the root by removing the GP

Question 51

What are the features of the nayyar core?

Answer 51

• retention obtained by the undercuts in the divergent canals and pulp chamber
• 2-4mm GP removed from the canal and replaced with amalgam
• immediate placement of and coronal preparation can be done at the same appointment

Question 52

What two restorative materials that can bond to amalgam?

Answer 52

RMGIC and GI

Question 53

Which bond strength is stronger amalgam or composite?

Answer 53

composite

Question 54

What special investigation should you do and why for a patient that attends with a space between 13 and 14 ?

Answer 54

Screen using BPE to obtain score and then decide on investigations according to score
- PGI - to assess plaque and bleeding levels
- 6PPC - to assess periodontal disease, pocketing, mobility and gingival recession
- Periapical radiographs to check for any periapical pathology and bone levels
- study models to monitor change over time

Question 55

Other than aesthetics why would restoring this space be challenging?

Answer 55

• The space is small if the teeth are of good prognosis removing healthy tooth tissue for crowns or veneers would be a difficult choice to make
• If using composite to close the space by making 13 or 14 bigger this can be noticeable to the patient

Question 56

What problems are associated with implant placement in the case of space between 13 and 14? (small space)

Answer 56

• inadequate space for implant placement (7mm required)
• inadeqaute bone levels due to periodontal disease
• cost
• periodontal disease
• Poor aesthetics as there is no good space for a tooth

Question 57

What are the different types of pathological tooth wear?

Answer 57

• attrittion : physiological loss of teeth tissue due to tooth to tooth contact
• erosion : loss of tooth surface by chemical process by acid
• abrasion : physical loss of tooth tissue through an abnormal mechanical process that is indeoendent of the occlusion (toothbrushing)
• Abfraction : loss of hard tissue from eccentric occlusal forces leading to compressive and tensile stresses at the cervical fulcrum areas of the tooth

Question 58

What are the BEWE scores ?

Answer 58

0 - no erosive wear
1 - loss of enamel texture
2- distinct defect hard tissue loss for less than 50%
3- hard tissue loss for more than 50% of the surface

Question 59

how to calculate BEWE scores

Answer 59

Score each sextant then add it up to assess risk
2> none
3-8 low
9-13 medium
>14 high

Question 60

Name three ways teeth can be desensitised?

Answer 60

• Sensitivity toothpaste
• Prime and bond to protect surfaces
• Fluoride varnish

Question 61

What is the DAHL technique?

Answer 61

It is a technique used to gain interocclusal space in localised anterior toothwear cases without tooth reduction over a period of 3-6 months. An appliace such as a composite platform is placed anteriorly to increase the OVD by 2-3mm this allows the posterior teeth to erupt into occlusion and the anteriors intrudes. This then creates space for to allow restorations of the anterior teeth without further tooth reduction.

Question 62

List 4 contraindicated groups for using DAHL technique?

Answer 62

• patients with active periodontal disease
• patients with TMJ problems
• patients who are on bisphosphonates
• post orthodontic treatment
• if dental implants exist

Question 63

What are the consistuents of composite and give examples for each?

Answer 63

• Resin - Bis-GMA
• Glass - Silica or quartz
• Low weight dimethacrylate -TEGDMA
• light activator - camphorquinone
• Silane coupling agent - bifunctional molecule binding resin and filler

Question 64

On a cervical abrasion cavity why would use RMGI instead of composite?

Answer 64

• due to poor moisture control at the cervical region, meaning that there is higher rate of composite restoration failure.
• RMIC has less polymerisation shrinkage and is best suites for cervical abrasion lesions where moisture cannot be controlled

Question 65

What is an RPI?

Answer 65

it is a stress relieving clasp system which is used in free end saddle designs to prevent stress on the last abutement tooth and can also provide reciprocation

Question 66

What are the components of the RPI system?

Answer 66

• Occlusal mesial rest
• Distal proximal plate (with 2-3mm undercut to guide movement)
• gingivally approaching I-bar clasp (at greatest prominence of the tooth)

Question 67

What is the mechanism of action of RPI system?

Answer 67

The rest mesially acts as the axis or rotation. As the proximal plate and I bar rotates downwards and mesially around the axis of rotation during occlusal load. This allows it to disengage from the tooth and undercuts, thus avoiding potentially traumatic torque.

Question 68

How would you identify a vertical bony defect?

Answer 68

PA radiographs
6 point pocket chart

Question 69

Explain how vertical bony defects occur?

Answer 69

Commonly occurs in posterior teeth when plaque accumulate on one side of the tooth.The radius destruction of plaque determines this patterns. It is approximately 1.5-2mm and if the inter proximal bone is greater than this then the pattern is vertical/angular in nature.

Question 70

How is vertical bony defects classified?

Answer 70

Using Goldman HM and Cohen (number of walls)
1 wall defect
2 wall defect - heals better
3 wall defect - heals better

Question 71

What are the treatment options for vertical bony defects?

Answer 71

• Closed or open root surface debridement to allow healing by repair
• pocket elimination with osseous resection where the flap is repositioned apically
• Regenerative technique such as grafting for new bone, periodontal ligament and cementum

Question 72

How do you determine the success rate of hygiene phase therapy?

Answer 72

• using SDCEP guidelines
• when bleeding is less than 10% , plaque less than 15% and pocket depths less than 4mm
• This may be no be achievable for all patients so a significant improvement in oral hygiene and reduction in pocket depths, bleeding and plaque from baseline readings can be deemed successful

Question 73

If a patient is deemed suitable for periodontal regenerative surgery. What are the indications for this?

Answer 73

2 and 3 wall defects
Grade 2 furcation in mandibular teeth
Grade 2 buccal furcation in maxillary molars

Question 74

If regenerative surgery fails for vertical bony defects , what are the alternative treatment options?

Answer 74

• Root resection
• XLA
• Palliative care

Question 75

A fractured core and crown on a non root treated tooth , what features of the remaining tooth structure that will determine the prognosis of the tooth?

Answer 75

• Size of exposure
• Time of exposure
• Vitality of the tooth
• Remaining tooth tissue

Question 76

What luting cement is used for MCC adhesive bridges?

Answer 76

RMGI luting cement (Relyx) - HEMA monomer
Dual-cure resin cement (panavia) - 10-MDP monomer

Question 77

What makes RMGIC better than GIC? and why can it be used for enamel-dentine fractures instead of GI?

Answer 77

• prevents micro leakage more than GI
• Seals the cavity better
• Higher compressive strength
• Higher tensile strength
• Higher bond strength
• less solubility than GIC

Question 78

Why GIC is not used as a conventional restorative material?

Answer 78

low mechanical properties:
* low toughness
* low fracture strength
* low wear resistance
Not good aesthetics
High solubility
lower bond strength

Question 79

Why is RMGIC not good as a luting cement?

Answer 79

• contains HEMA which causes it to swell when contaminated with moisture
• Cytotoxic to the pulp

Question 80

What are the ideal properties of a luting cement?

Answer 80

• thickness below 25 microns
• radiopaque
• Cariostatic
• low solubility
• high compressive strength
• biocompatible
• easy to use with good viscosity

Question 81

What luting cement is used for fibre post?

Answer 81

dual cure composite luting cement

Question 83

What are the components of temp bond?

Answer 83

• Base : zinc oxide, starch and mineral oil
• Accelerator - EBA, eugenol and carnauba wax

Question 84

Can you bond zirconia?and why?

Answer 84

No because it cannot be etched.
*However it has micro-mechanical retention and self etching composite with relyx bonds well to sandblasted zirconia

Question 85

Are lithium disilicate crowns strong? and how ?

Answer 85

Yes, they have good flexural strength as crack propagation through the material is difficult

Question 86

What is a good use of lithium disilicate crowns?

Answer 86

• can be good in adhesive bridges as they create a strong bond with resin cements
• in anterior teeth

Question 87

How do you bond to non precious metals?

Answer 87

By sandblasting them with aluminium oxide: using10 MDP (panavia) or 4META

Question 88

What type of bridge is used to replace missing laterals?

Answer 88

Mesial cantilever resin bonded bridge (first choice)
Fixed-fixed bridge

Question 89

What abutment teeth can be used for a resin adhesive bridge to replace a lateral incisor?

Answer 89

Canine or central incisors

Question 90

Why are mesial cantilever designs preferred over distal cantilevers?

Answer 90

this is due to the increased biomechanical levering forces around the abutment, which acts as a fulcrum.

Mesial cantilevers distribute occlusal forces more favorably. Forces on the mesial side are typically directed more along the long axis of the supporting tooth, which can better withstand these forces.
Distal cantilevers tend to create a longer lever arm effect, increasing the potential for torque and rotational forces on the abutment tooth. This can lead to increased stress and potential failure of the restoration

Question 91

What information is needed from a patient for technician to make a bridge ?

Answer 91

• bridge design
• master impression
• Bite registration
• Shade of teeth

Question 92

What are alternative options for replacing lateral incisors other than bridges?

Answer 92

RPD
Implants
Do nothing

Question 93

In a periodontal chart, what results would show teeth with poorest prognosis?

Answer 93

• Loss of attachment : pockets of more than 4mm means increased tooth loss
• Mobility : loss of bone support result in increased tooth loss
• Furcation involvement : more difficult to clean, more caries risk

Question 94

What patient factors affect prognosis of teeth in periodontal patients?

Answer 94

• Poor oral hygiene
• Smoking
• Medical history such as diabetes and immunosuppression, pregnancy
• Drug history

Question 95

What could be causing anterior drifting and increase in overjet in an elderly patient?

Answer 95

Active and uncontrolled periodontal disease

Question 96

What are the Local causes of periodontal disease?

Answer 96

• Calculus build up
• malpositioned teeth
• overhanging restorations
• partial dentures
• poor oral hygiene

Question 97

What are the systemic causes of periodontal disease?

Answer 97

• Medical conditions : such as diabetes, cardiovascular disease, immunosuppression, rheumatoid arthritis and osteoporosis
• Smoking
• Patient factors such as : stress, diet, obesity and pregnancy
• Medications such as : Calcium chanel blockers (amlodipine), anti-epileptics (phenytoin), immunosuppressants (cyclosporine)

Question 98

What are the treatment options for an old patient presenting with periodontal disease?(mobility and drifting with increased overjet)

Answer 98

1) control periodontal disease : start with BPE and then hygiene phase therapy inculding OHI advice , patient education and control risk factors, review restoration margins and clear out any overhangs , denture hygiene , then review and move to step 2 if engaging
2) for mobility control splint the teeth
3) consider orthodontic treatment after that

Question 99

What are the causes of denture stomatitis and loose dentures? (8)

Answer 99

• Immunosuppression : diabetes and HIV
• Poor dental hygiene
• Poor denture hygiene (wearing dentures overnight)
• Trauma from ill fitting dentures
• Xerostomia
• Systemic steroid use
• Broad spectrum antibiotic use
• high carbohydrate diet

Question 100

What microbes are involved in denture stomatitis?

Answer 100

Candida species : candida albicans and candida tropicalis
Staphylococcus species - staphylococcus aureus and staphylococcus epidermis

Question 101

What is the initial treatment plan for denture stomatitis?

Answer 101

1)local measures
* brush palate daily and after denture after eating
* clean denture by soaking in CHX twice daily for 15 mins
* Rinse mouth twice daily with CHX
* Do not wear dentures overnight
* Smoking Cessation
* Rinse after inhaler use
* Refer to GDP of suspected underlying medical condition
2)Denture adjustment
* Relign denture
* make new denture
* prescribe tissue conditioner
3) drug treatment if required
* systemic fluconazole - 50mg - 1x7days
* topical miconazole oromucosal gel 20mg/g - pea size on denture pea size on denture fitting surfaces 4x for 7 days after lesion heals

Question 102

Give two topical agents that can be used for the treatment of denture stomatitis?

Answer 102

• Miconazole oromucosal gel 20mg/g
• Nyastatin oral suspension 100,000 units/ml

Question 103

What would you see on the occlusal surfaces of a patient who have denture stomatitis and uses an inhaler?

Answer 103

• Erosion due to inhaler use
• patient should be advised to rinse after inhaler use
• fluoride varnish can be applied on the teeth to help protect them and reduce sensitivity

Question 104

What to do to improve denture stomatitis in the short term until it is healed?

Answer 104

prescribe a tissue conditioner

Question 105

Patient unable to tolerate new dentures after wearing the old one for 20 years , the previous ones has became loose over the past 18 months, what can be different between the old and the new denture? (5)

Answer 105

• OVD may have changed
• Path of insertion may have changed
• Different flange extension
• Different palatal extension
• different tooth shade and shape

Question 106

What are the relief areas in a complete denture?

Answer 106

• incisive papilla
• mid-palatine torus

Question 107

What method can be used to make a denture that a patient could tolerate when replacing an old denture?

Answer 107

Replica dentures

Question 108

What methods can dentists use to improve the fit of loose dentures?

Answer 108

• Reline - soft or hard lining material
• Rebase
• Remake denture

Question 109

Identify features on the hard palate that may cause problems with dentures?

Answer 109

• high arched palate
• tori on the palate

Question 110

What things should be checked at the try in stage?

Answer 110

• Extensions
• Retention and stability
• Occlusal plane
• occlusion (RVD, OVD and freeway space)
• Appearance (Position of the teeth, shade and shape)
• Speech

Question 111

What is the shortened dental arch?

Answer 111

It is a dentition where most posterior teeth are missing but there is still satisfactory oral function without the use of RPD

Question 112

What is the minimum requirement for an SDA?

Answer 112

3-5 occlusal units remaining
* occluding pair of premolars = 1 unit
* occluding pair of molars = 2 units

Question 113

SDA gives priority to maintain which teeth?

Answer 113

Anteriors and premolars

Question 114

How many units for 2 occluding premolars and a pair of molars?

Answer 114

4 units

Question 115

Why is periodontal disease is a contraindication for SDA?

Answer 115

• drifting of periodontally compromised teeth under occlusal load
• loss of alveolar bone leading to compromised denture bearing area in the long term
• loss of the neutral zone for denture teeth in the long term
• Distal tooth migration can occur in SDA due to increase in anterior load leading to interdental spacing that can be exacerbated by periodontal disease

Question 116

What is the neutral zone in complete dentures?

Answer 116

It is the area in the potential denture space where the forces exerted outwards by the tongue are neutralised by the cheeks and lips action inwards

Question 117

What skeletal classes are contraindicated with SDA and why?

Answer 117

In severe class II and III malocclusion as may cause occlusal instability leading to difficulties with function such as chewing , it may also lead to or worsen TMD symptoms

Question 118

What metal is used for casting adhesive bridges?

Answer 118

• NiCr and CoCr sandblasted with aluminium oxide (50 microns)

Question 119

What metal is used in adhesive bridges retainers?

Answer 119

CoCr or NiCr

Question 120

What cement is used for adhesive bridgework?

Answer 120

Panavia (10MDP) - anaerobic dual cure resin cement

Question 121

What is the 10 year and 5 year survival rate for RRB?

Answer 121

5 year - 80.8
10 year - 80.4

Question 122

What are the indications for SDA?

Answer 122

• Missing posterior teeth but have 3-5 occlusal units remaining
• Sufficient occlusal contacts to provide sufficient occlusal table
• Patient does not want a complicated treated such as RPD
• Patient cannot afford dental treatment
• Good prognosis of remaining anterior and posterior teeth

Question 123

What are the contraindications for SDA? (5)

Answer 123

• periodontal disease
• TMJ problems
• poor prognosis of remaining teeth
• Severe class II or class III
• any signs of pathological toothwear

Question 124

Sub alveolar fracture of 12 and 11present with enamel dentine fracture >1mm exposure and >24h , what is the immediate management of tooth 11?

Answer 124

• Locate missing fragment of the tooth and refer to A&E if querying aspiration risk
• numb the area using LA and place rubber dam and carry out partial pulpotomy by accessing and removing part of the coronal pulp (2mm), and achieve haemostasis using cotton wool and pressure
• If haemostasis is achieved place CaOH in canal and seal with RMGIC and a composite restoration
• If haemostasis is not achieved or pulp is hyperaemic or not bleeding then carry out full pulpectomy and restore as above

Question 125

A sub alveolar fracture is of poor prognosis why is that?

Answer 125

• It results in lack of coronal tissue to bond and support restoration. This leads to the inability to achieve moisture control for restoration and inability to take impressions for indirect restorations.
• Inability to establish marginal integrity and the patient will may have difficulty cleaning

Question 126

Patient attends with caries on the palatal of 12; he is also sensitive to sweet under bridge, what type of bridges can you get anteriorly?

Answer 126

• fixed cantilever
• spring cantilever for incisors
• fixed fixed bridge

Question 127

what pulpal diagnosis would you give to a tooth that is sensitive to sweet?and why?

Answer 127

reversible pulpitis
- discomfort from sweet stimuli and goes away within seconds when stimuli is removed
- Short sharp pain
- No TTP
- Pain on cold
- Well localised pain

Question 128

What are the nerves affected in reversible pulpitis and what is this called?

Answer 128

a-delta and A-beta fibres due to hydrodynamic microleakage stimulation

Question 129

What design would you use for replacing tooth 12 to decrease debonding?

Answer 129

An adhesive cantilever bridge from tooth 11. If this de-bonded it would fall out and would not become a plaque trap leading to less risk of caries . Also if an adhesive cantilever fails it is less destructive than other types of bridges.

Question 130

What 4 faults can occur to cause a debond?

Answer 130

• Parafunctional habits
• Poor moisture control during cementation
• Unfavourable occlusion
• Trauma to face or oral cavity
• Poor oral hygiene

Question 131

A patient undergone periodontal treatment presents as an emergency patient with pain on the 11 with swelling, TTP and lymphadenopathy - give 2 differential diagnosis?

Answer 131

• Periodontal abscess
• Periapical abscess

Question 132

Give two special investigations to confirm diagnosis if suspected periodontal or periapical abscess?

Answer 132

• Sensibility testing EPT and ECT ( positive in periodontal abscess)
• Periodontal charting - check other teeth to see periodontal involvement
• PA radiographs to show if there is a periapical radiolucency present

Question 133

State two ways that you can drain an abscess?

Answer 133

• incision or pocket retraction and irrigate with CHX/saline

Question 134

Give initial management of a periodontal abscess

Answer 134

• incise and drainage of the abscess
• Gentle sub-gingival debridement short of the base of the pocket to avoid trauma and to limit spread of infection
• warm saline mouthwash or CHX
• OHI
• Analgesics for pain relief
• Antibiotics due to systemic involvement (amoxcillin 500mg 3x for 5 days )
• Review within 10 days and follow up with HPT

Question 135

4 ways to check debonding of a bridge clinically?

Answer 135

• Probe around the bridge abutments and wing
• Push and check for any air bubbles
• Floss around bridge
• Check visually for. areas that have debonded

Question 136

What is the best bridge option for a missing anterior tooth with adjacent teeth prepped?

Answer 136

• Spring cantilever as RRB cannot be used on adjacent teeth as they prepped

Question 137

What factors should be checked by a dentist for placing implants?

Answer 137

General - smoking history, MH (bisphosphonate use)
Local - alveolar bone height and width and space available for implant (7mm between crowns)

Question 138

What are the edentulous classifications for maxiilla?

Answer 138

Atwood cawood and howell classification
1- dentate
2- post extraction
3 - rounded ridge with adequate bone height and width
4- knife edge ridge with adequate height and inadequate width
5 - flat ridge , inadequate height and width (no alveolar process
6 - depressed ridge with basal bone loss

Question 139

What classifications of ridges are considered poor?

Answer 139

4,5,6

Question 140

Define retention in partial dentures?

Answer 140

The resistance to vertical displacement

Test resistance by pulling denture vertically from anterior teeth

Question 141

What is indirect retention in partial dentures?

Answer 141

• resistance to rotational displacement of the denture

Question 142

How does composite bonds to dentine ?

Answer 142

• acid etching dentine with 35% phosphoric acid removes the smear layer which expose dentinal tubules and collagen fibre’s
• Prime and bond applied and penetrated collagen fibres and dentinal tubules leading to a micro-mechanical bond
• prime and bond is a bivalent molecule which bonds to dentine through the hydrophilic end and bonds to composite through the hydrophobic end through molecular entanglement

acid etch removes smear layer , DBA creates hybrid layer between dentine

the bond between composite and acid etched enamel is micromechanical

Question 143

How is porcelain treated to improve retention?

Answer 143

Etched with hydrofluoric acid producing a rough retentive surface , then it is treated by a silane coupling agent to produce a strong covalent bond

Question 144

name 2 luting cements other than resin based that could be used to bond a crown?

Answer 144

• Gi luting cement (aquacem)
• Zinc phosphate cement

resin based bond better due to lower solubility and stronger bond

non resin cements are easier to handle and may provide fluoride release

Question 145

What is the advantages of placing crowns in posterior teeth?

Answer 145

• Reinforce and strengthen tooth structure more than a direct restoration

Direct restorations may be more susceptible to fracture due to pressure configeration factors

Question 146

How does a resin based luting cement bonds to porcelain?

Answer 146

• HF etched procelain
• silane coupling agent applied and produce a silane molecule that reacts with resin luting cement producing a strong covalent bond

C-C bond to composite and C-OH bond to porcelain

A silane coupling agent bonds organic meterials to inorganic materials

Question 147

potential causes of symptoms on a patient presenting of pain to transient stimuli under a recently replaced MOD composite restoration

Answer 147

• Pulpal exposure
• uncured resins entering the pulp and causing irritation
• poor moisture control when placing the restoration
• insufficient coolant during preparation damages pulp
• Deep cavity with no liner placed
• high occlusal contacts

Question 148

What 5 things you could do to avoid pain after replacing an MOD composite restoration?

Answer 148

• Using dental dam for good moisture control
• Placing lining material under restoration (RMGI)
• place and cure composite in increments
• Place pulp cap if pulpal exposure (Dycal)
• provide splint if patient have bruxism
• Apply fluoride varnish

Question 149

Describe the 4 intraoral signs of ANUG

Answer 149

• halitosis
• crater like ulcers
• grey superficial layer that can be wiped off
• reverse gingival architecture
• painful ulceration on the tips of the interdental papilla
• bleeding

Question 150

What bacteria is involved in ANUG?

Answer 150

fusobacterium species
provotella intermedia

Question 151

What 4 risk factors predispose someone to anug?

Answer 151

• Smoking
• Stress
• immunosuppression
• Poor oral hygiene

Question 152

What is the initial management of ANUG?

Answer 152

• Check airway if compromised or not , if compromised call 999
• Prescribe analgesia
• Start step 1 periodontal therapy as symptoms allow ( LA may be required)
• prescribe CHX mouthwash or hydrogen peroxide
• If systemic involvement prescribe : metronidazole -> doxycycline -> azithromycin
• Review within 10 days , carry out further PMPR

Question 153

What is TIPPS for oral hygiene?

Answer 153

• Talk - about causes, risks and prevention of periodontal disease
• Instruct - the best way to perform effective plaque removal
• Practice - practice cleaning teeth and performing interdental brushing in clinic
• Plan - plan how OH can fit in the patient daily routine
• Support - follow up with patient

Question 154

Why might a post and core debond? (5)

Answer 154

• post or core fracture
• bruxism
• inadeqaute moisture control when cementing
• root fracture
• Caries

Question 155

Reasons why fracture occurs at the junction of the post and core?

Answer 155

• Parafunctional habits (bruxism)
• Inadeqaute ferrule
• Caries
• poor post placement

Question 156

What are 3 ways of removing a post?

Answer 156

• mosquito forceps
• masseran kit
• eggler
• ultrasonic vibration

Question 157

A 28 fit and healthy patient showing periapicals of generalised bone loss , what is your diagnosis?

Answer 157

generalised agressive periodontitis

Question 158

What 4 signs can lead you to the diagnosis of aggressive periodontitis?

Answer 158

• Generalised loss of attachment affecting at least 3 other teeth except 6s and incisors
• Affect patient under 30 yrs
• vertical bony defects
• Episodic nature of destruction of periodontal attachement and associated structures
• Rapid progression of bone loss
• plaque levels not consistent with disease level seen

Question 159

What are the clinical and lab investigations for aggressive periodontitis?

Answer 159

• Thorough history taking
• BPE, MBPS, 6PPC
• cervicular fluid swab for microbiological analysis

Question 160

How to decide prognosis of individual teeth in periodontitis?

Answer 160

• Loss of attachment
• Mobility
• Furcation involvement

Question 161

What is the treatment plan for aggressive periodontitis?

Answer 161

• Perform Step 1 according to BSP guidelines
• Refer to specialist
• prescribe CHX

Question 162

What is the justification behind using a lingual bar connector ?

Answer 162

• Give clearance for the patient to clean
• 8mm clearance from gingival margin to FoM (3mm from gingival margin, 4mm bar , 1mm above floor of mouth)
• well tolerated (pt comfort)

Question 163

What features on an RPD might provide indirect retention?

Answer 163

• RPI systems
• Rest seats
• Major connector
• guiding planes

Question 164

Why would mechanical root surface debridement not be successful in eliminating pocket bacteria? (5)

Answer 164

• Inadequate RSD due to poor operator technique and experience
• Specific pocket sites are not accessible
• Failure to disrupt the biofilm
• Patient not compliant with OH
• Patient is immunocompromised

ABs may not reach the pocket depth

Do not use antibiotics when there is no systemic involvement

Question 165

When to use antibiotics?

Answer 165

• when there is systemic involvement or pt is immunocompromised

Question 166

How to manage a periodontal abscess that have systemic involvement?

Answer 166

• Sub-gingival scaling short of the root base (avoid infection spread and damage)
• Drain pus by incision or through pocket
• Give patient advice on analgesics for pain relief
• Use 0.2% CHX until acute symtpoms subside
• ABS : amoxicillin or metronidazole

Amoxicillin 500mg , metronidazole 200mg three times daily for 5 days

Question 167

What is a periodontal abscess?

Answer 167

acute exacerbation of a periodontal pocket caused by trauma to the pocket epithelium or obstruction of the pocket entrance due to bacteria and food accumulation without adequate cleaning leading to periodontal abscess

Question 168

What 3 criteria must be fulfilled before obturation?

Answer 168

• Tooth must be asymptomatic
• Canal should be fully dried
• Full biomechanical cleaning on all canals

Question 169

Name the consistuents of GP

Answer 169

GP
zinc oxide 65%
radio-pacifiers 10%
plasticisers 5%

ZnO can alleviate pain and is bacteriostatic + a good seal

Question 170

What is the function of canal sealers when used with GP cones? (3)

Answer 170

• seal space between dentinal walls and core
• fill voids and irregularities in canal and between GP cones
• Lubrication during obturation

Question 171

What types of sealers are used for obturation? (5)

Answer 171

• CaOH (Dycal)
• Epoxy resin filler (AH26 plus)
• Bioceramic sealer (calcium silicate and calcium phosphate)
• RMGI
• ZOE

Question 172

How do you assess obturation on a radiograph? (4)

Answer 172

• check correct length
• check correct taper
• check density and that GP is well compacted with no voids
• check that GP and sealer is removed at facial ECM in anterior and Canal orifices in posteriors

Question 173

Why do we need to obturate? (3)

Answer 173

• seal remaining bacteria
• prevent reinfection
• provide apical and coronal seal

Question 174

Give 4 methods of obturation? (CCCW)

Answer 174

• cold lateral compaction
• warm vertical compaction
• continuous wave compaction
• carrier based obturation (thermafil)

Question 175

What 2 temporary restorations can be provided for a patient with a fractured crown core on tooth 11 during endo?

Answer 175

• RMGIC
• provisional post crown
• Vacuum stent with tooth (if tooth is present)

Question 176

Post materials

Answer 176

Metals - SS, type IV gold
Ceramics - aluminia and zirconia
Fibre - Carbon and glass fibre

Question 177

Core materials

Answer 177

• composite
• amalgam
• glass ionomer

Question 178

What factors can determine post length?

Answer 178

• root length and morphology
• type of post used
• crown length
• remaining tooth structure

Question 179

What are the ideal dimensions for post placement?

Answer 179

• leave 4-5mm of GP in canal
• At least half of post length should go in the root
• 1:1 post length to crown height
• width should be no more then 1/3 of the root width at norrowest point

Question 180

What materials can be used to cement post and core?

Answer 180

• GI luting cement
• composite resin luting cement

Question 181

Explain the main features in mastication and ingesion?

Answer 181

1. ingestion > movement of food into mouth
2. stage 1 oral transport > movement of food from front to back of mouth
3. mechanical processing > food mixes with saliva and produces bolus which is sqaushed against hard palate by the tongue , and food chewed by molars and premolars
4. stage 2 oral transport > bolus moves from anterior to posterior of the oral cavity , solid food moves to pharyngeal surface of the tongue then to oropharynx and liquids held by posterior oral seal then into oropharynx
5. swallowing : bolus moves from pharynx to esophagus

Question 182

What muscles are involved in ingestion?

Answer 182

buccinator and orbicularis oris

Question 183

What anatomical structures are involved in stage 1 oral transport?

Answer 183

• tongue
• retraction of hyoid bone
• narrowing of the oropharynx

Question 184

What muscles are involved in swallowing?

Answer 184

• upper esophageal sphincter
• epiglottis (preventing backflow)
• peristalis moves food to stomach

Question 185

What factors improve masticatory performance?

Answer 185

• Sufficient oral saliva
• Sufficient dentition

Question 186

3 aspects of oral function regarded by proponents of the shortened dental arch as acceptable?

Answer 186

• sufficient occlusal and mandibular stability
• Occlusal attrition
• Satisfactory oral function

Question 187

What is occlusal stability?

Answer 187

Stability of tooth position in relation to its spatial relationship in the occluding dental arches

Question 188

What is occlusal stability ?

Answer 188

It is the stability of tooth position relative to its spatial relationship in the occluding arches

Question 189

What are the factors contributing to occlusal stability? (4)

Answer 189

Absence of pathology
periodontal support
occlusal contacts
mandibular stability

Question 190

What are the requirements for occlusal stability?

Answer 190

• Stable contacts on all teeth in ICP
• disclusion of posterior teeth when mandible is protruded
• anterior guidance is in harmony with envelope movement
• Disclusion of the posterior teeth on the working side during mandibular lateral movements
• Disclusion of the posterior teeth on the non working side during mandibular lateral movements

Question 191

Types of interventions for inadequate bone levels ?

Answer 191

• guided tissue regeneration
• bone grafting
• biological mediators such as emdogain (enamel matrix deriviative)

Question 192

How to find the aetiology of discolouration of a discoloured tooth that sustained trauma long time ago ?

Answer 192

• History
• Sensibility testing
• Radiographic assessment (PA)
• Compare with clinical photographs
• Type of discolouration

Question 193

What are the treatment options for a discoloured tooth?

Answer 193

• enamel microabrasion (HCL and pumice)
• Veneer
• bleaching (vital or non vital)
• localised composite restoration
• Accept and monitor

Question 194

Describe the appearance of a vertical bony defect?

Answer 194

• V shaped and sharply outlined adjacent to tooth

Question 195

What happens to an upper arch with complete dentures and lower anterior teeth present if the lower is not provided with a partial denture?

Answer 195

• Combination syndrome leading to a flabby ridge

This is caused by forces directed at the anterior region of the complete denture resulting in excessive and rapid bone loss in the anterior maxillary ridge that is replaced by excess fibrous tissue

Question 196

How is combination syndrome managed impression taking wise?

Answer 196

• take a mucostatic impression where tissues are recorded at rest
• Use a 2 stage impression : first impression with medium body silicone then cut out impression material over flabby ridge and take a second impression using light weight body silicone
• Use window technique where relief holes are cut in special trays to allow flow of impression material and leave tissues undisplaced - using low viscosity impression material

Question 197

What are the 4 stages of caries removal?

Answer 197

• Access - remove enamel using high speed following the caries at ACJ
• extent - check extent of caries at the ADJ and clear staining , smooth enamel cavosurface margins
• remove dentinal caries - remove dentinal caries peripherally then deep caries at pulpal floor : using excavator or slow speed
• modification : choose restorative material, smooth edges and do any modifications

Question 198

When a cavity is unretentive for Amalgam , what 4 alternative techniques or materials can you use?

Answer 198

• internal dimensions of the cavity must be greater to the access into it
• Undercuts required
• at least 2mm cavity depth is required for AM
• Add dovetail to prevent dislodging
• cavosurface margin of amalgam should be 90-120 - butt joint

Question 199

What would you look for if you place a restoration on a non root treated tooth at review?

Answer 199

• Sensibility testing to check pulpal response
• Radiographic changes

Question 200

How does the clinical presentation of caries compares to a radiograph?

Answer 200

• 2-3mm deeper clinically than shown on radiograph

Question 201

Describe the procedure of Cveck pulpotomy

Answer 201

• used for traumatic exposures (partial pulpotomy)
• inflammed pulp beloww exposure is removed 2-3mm until reaching healthy tissue
• bleeding controlled using CHX
• Site covered with CaOH or MTA(in anteriors)
• then RMGI placed

Question 202

What is the procedure in a normal pulpotomy?

Answer 202

• Dental dam and LA
• remove caries and roof of pulp chamber
• remove coronal pulp , haemorrhage control and evaluate root stumps
• to control bleeding ferric sulphate can be used with cotton pledge for 20 seconds
• Restore : cover stumps with ZOE or CaOH or MTA then place GIC for performed crown

Question 203

Name 4 different types of composite?

Answer 203

microfilled
nanofilled
hybrid
flowable

Question 204

What are the clinical disadvantages of composite and how are they minimised?

Answer 204

• polymerisation contraction stress - place composite on no more than one surface at a time
• Post operative sensitivity - by ensuring good moisture control and correct bonding
• Moisture sensitive - use dental dam
• Soggy bottom - place composite in increments

Question 205

What are the advantages of composite over amalgam? (4)

Answer 205

• extended working time - on demand set
• minimal preparation - tooth tissue preserved
• Better aesthetics - range of shades
• Bonds chemically to tooth

Question 206

What is the response of
Healthy periodontium
Reduced periodontium
Pathological periodontium
to traumatic occlusion?

Answer 206

• healthy periodontium : widening of the PDL, no loss of attachment and inflammation , resolved with resolving occlusion
• Healthy but reduced periodontium: same as above but due to reduced periodontium there will be increased mobility
• Periodontitis - widening of PDL; loss of attachment, bleeding on probing and plaque present , increased mobility

Question 207

How do you manage a traumatic occlusion in patients with periodontitis?

Answer 207

• address the causative problem such bruxism or high restorations
• adjust occlusion if high
• Splint if any parafunctional habits
• Splint if mobility present
• Use of a bite raising appliance
• Step 1 perio treatment

Question 208

What factors influence localised mobility? (5)

Answer 208

• Periodontal disease
• Traumatic occlusion leading to widening of the PDL
• Alveolar bone loss
• trauma
• Smoking

Question 209

When might splinting be advised in periodontal treatment?

Answer 209

• when there is increased mobility due to advanced loss of attachment
• splinting mobile teeth can also aid in PMPR and root surface debridement as the teeth will be stabilised

Question 210

Why is there a decrease in mobility after periodontal treatment?

Answer 210

• due to increased tissue tone and regain of junctional epithelium attachment

Question 211

What can you do if the PDL is widened after successful periodontal treatment? in a patient with traumatic occlusion

Answer 211

• Reduce high contacts that are causing traumatic occlusion

Question 212

What is fremitus?

Answer 212

• it is a sign of tooth mobility in regard of traumatic occlusion : seen as mobile tooth that is in a traumatic occlusion
• can asses by palpating the teeth

Question 213

• soreness in right cheek with redness in buccal mucosa
• lacey edge adjacent to tooth 47
• tooth 47 shows 6mm mesio-buccal pocket with bleeding
• pt wears partial denture Cocr for 5 years
• PA of 47 show mesial bone loss with PA pathology

What is the differential diagnosis

Answer 213

• Chronic periodontal disease
• Traumatic lesion from denture
• Lichenoid tissue reaction to amalgam
• Lichen planus
• Oral cancer??

Question 214

Based on the previous question

• What special investigations would you take

Answer 214

• biopsy for histological examination - refer to oral surgery or oral medicine
• Clinical photographs to monitor change
• 6PPC
• OPT radiograph
• patch testing for CoCr allergy
• Denture assessment

Question 215

Based on the previous question

What are the treatment options?

Answer 215

• lichenoid reaction - replace amalgam restoration
• chronic periodontal disease - Step 1 periodontal treatment
• Lichen planus - correct deficiencies, medication use ; SLS free toothpaste
• Oral cancer - refer to OM
• Traumatic lesion - adjust CoCr clasps

Question 216

• 68 year old patient with upper and lower partial acrylic which are poorly fitting
• upper arch have deep to moderate caries
• Periodontal pockets 3-4mm with no radiolucencies
• Radiopacities in relation to all the roots
• minimal periodontal bone loss
• on medication for Paget’s disease

Describe the anatomical changes, pathology and incidence behind the reason why the denture no longer fits

Answer 216

• Paget’s disease causes increased bone turnover (increased osteoclasts and osteoblasts activity), leading to bone swelling causing ill fitting dentures
• Affects M>F , ages above 40

Question 217

• 68 year old patient with upper and lower partial acrylic which are poorly fitting
• upper arch have deep to moderate caries
• Periodontal pockets 3-4mm with no radiolucencies
• Radiopacities in relation to all the roots
• minimal periodontal bone loss
• on medication for Paget’s disease

Why could he develop caries? (4)

Answer 217

• due to xerostomia and polypharmacy
• High Sugar diet
• ill fitting denture may act as a plaque trap
• Reduced manual dexterity with age which causes poor OH

Question 218

• 68 year old patient with upper and lower partial acrylic which are poorly fitting
• upper arch have deep to moderate caries
• Periodontal pockets 3-4mm with not radiolucencies
• Radiopacities in relation to all the roots
• minimal periodontal bone loss
• on medication for Paget’s disease

What might cause the radiopacities on the radiograph?

Answer 218

Paget’s disease causing hypercementosis

other dental changes of paget’s disease include : loss of lamina dura and tooth migration due to bone enlargement

Question 219

• 68 year old patient with upper and lower partial acrylic which are poorly fitting
• upper arch have deep to moderate caries
• Periodontal pockets 3-4mm with no radiolucencies
• Radiopacities in relation to all the roots
• minimal periodontal bone loss
• on medication for Paget’s disease

What are the treatments you would provide and what treatments would you avoid?

Answer 219

• Step 1 periodontal treatment (diet, OHI , PMPR)
• Caries management , may require RCT for extensive caries
• New dentures - may need to be changed frequently regarding disease progression
• Regular monitoring and assessment
• refer to specialist services due to paget’s disease
• avoid extractions as may bleed more in osteoporotic phase due to more vessels , and may cause dry socket in sclerotic phase + risk of MRONJ

Question 220

What precautions would you take when extracting a tooth for a patient with bisphosphonates? (8)

Answer 220

• Find out if patient is on IV or oral bisphosphonates and for how long have he been taking them
• Ask oral surgery or oral medicine for advice
• avoid traumatic or surgical extraction (raising a flap)
• consult with prescribing clinician if interruption of medication is required
• Advice on oral hygiene
• Advice to use CHX twice daily for 1 week , immediately before extraction and 2 months after extraction
• Review in 2 months
• refer to specialist services if complications occur

Question 221

What is paget’s disease?

Answer 221

inflammatory bone disease causing bone expansion and weakening of the bone due to an increased osteoblasts and osteoclasts turnover
*aetiology unknown
* can be monostotic or polystotic
* may cause infection of tumour

Question 222

Incidence of paget’s disease

Answer 222

affect males more and patients over the age of 40

Question 223

What are types of paget’s disease?

Answer 223

• osteoporotic
• osteosclerotic
• mixed

Question 224

if you are carrying out an RCT and irrigating with sodium hypochlorite and suddenly the patient feels intense pain and you notice a marked facial swelling from the peri-radicular tissues

• what is the most likely cause for these signs and symptoms and why (3)?

Answer 224

• Extrusion of the sodium hypochlorite through the root apex into the surrounding tissues. This can occur due to
• high pressure injection of the solution
• locking the syringe in the canal
• wrong correct working length
• large apical constriction

Question 225

What are the signs and symptoms of extrusion of sodium hypochlorite from the root apex? (4)

Answer 225

• acute inflammatory reaction
• oedema
• bleeding
• tissue necrosis

Question 226

What is the immediate management of sodium hypochlorite extrusion? (4)

Answer 226

• reassure patient and tell them that this can be controlled and apologise
• administer LA for pain control
• irrigate canal with large amounts of saline
• Provide a datax and note incident in patient notes

Question 227

What is your management of a sodium hypochlorite incident after performing the immediate management? (5)

Answer 227

• Pain relief using analgesia (paracetamol or ibuprofin)
• cold compress for a few days then warm compress for swelling management and elimination of haematoma
• Review within 24h
• Prescribe antibiotics if systemic symptoms occur
• Refer to specialist if severe reaction

Question 228

How to prevent sodium hypochlorite extrusion? (6)

Answer 228

• careful pre-operative radiographs to check for any open apices and to determine accurate working length * Use rubber dam (single tooth isolation)
  *Do not put too much pressure on syringe and do not wedge
• Flush the canals with saline in the beginning to check that there is no leakage to soft tissues
• Label irrigation syringes correctly
• ensure silicone stop is at 2mm short of the working length
• Give patient protective eyewear and bib

Question 229

• patient with generalised pain under lower complete denture on left side
  *She wear an upper complete denture
• her denture has become progressively loose during the last 2 years
• on examination you find out a an unerupted second premolar that is now partially visible

Describe two radiographic positions to assess the position of the unerupted tooth ?

Answer 229

• using the parallax technique
• using an OPT and a PA / occlusal radiograph

Question 230

From the previous question

• patient with generalised pain under lower complete denture on left side
  *She wear an upper complete denture
• her denture has become progressively loose during the last 2 years
• on examination you find out a an unerupted second premolar that is now partially visible

Given that the mandibular area is very resorbed and the patient have osteoporosis what possible complications could arise if extraction has been attempted? (7)

Answer 230

• Risk of MRONJ due to bisphosphonate use
• bleeding
• swelling
• bruising
• infection
• dry socket
• nerve damage at the area of the mental nerve

Question 231

From previous question you decide with oral surgeon that the tooth should be in situ, outline your approach of a replacement denture design that would be stable and well tolerated by the patient? (5)

Answer 231

• placing a relief under the area of the second premolar by adding green stick to that area on the special tray when taking the impression
• Using soft lining material on the area of the second premolar
• Ensure denture is sufficiently extended and does not impinge the frenulum
• Ensure denture is retentive with sufficient support and stability
• ensure sufficient occlusion and accurate OVD, RVD and freeway space

Question 232

Pt asks about the alternatives of amalgam, usually what are patients concerns about amalgam? (6)

Answer 232

• aesthetics
• mercury poisoning and toxicity
• environmental impact
• tooth discolourations and surrounding tissues
• affect foetal development during pregnancy
• metal allergies

Question 233

How to reassure a patient about the safety of amalgam? (4)

Answer 233

• 350-400 amalgam restorations are required to cause mercury reactions
• Amalgam has been used in dentistry for over 150 years with no evidence based complications
• Amalgam on the environment is less problematic than consumption of seafood contaminated by methyl mercury
• There is not reliable evidence for not using amalgam on specific groups

Question 234

The EU advices to not use amalgam on which groups of patient and why? (3)

Answer 234

• breastfeeding women
• Pregnant women
• children under the age of 15
  This is due to phasing down the use of amalgam

Question 235

What aspects of the cavity preparation of amalgam ensure caries are removed?

Answer 235

• remove enamel to identify the extent of the lesion at ADJ using high speed
• then remove peripheral caries in dentine
• then deep caries on pulp floor
  ^ using slow speed or excavator

Question 236

What aspects of cavity preparation ensure that the restoration will be adequately cleans-able ?

Answer 236

• No unsupported enamel (overhangs)
• Removal of contact points
• Smooth margins
• Smooth occlusal surface

Question 237

Describe how dentine bonds to composite?

Answer 237

• acid etch is applied to dentine (10 seconds) which removes the hybrid layer ( 0.5-5 microns) exposing collagen fibres and dentinal tubules
• Dentine bonding agent is then applied and penetrate the dentinal tubules and the collagen fibres creating a micromechanical bond
• DBA is a bivalent molecule that bonds to dentine in one end through micro-mechanical retention in to dentinal tubules and collagen fibre’s (on the hydrophilic end) and binds to composite on the hydrophobic end through molecular entanglement creating hybrid layer

Question 238

How long is enamel acid etched and what is the bond created with acid etched enamel and composite?

Answer 238

• 20 seconds
• micro-mechanical retention

Question 239

What is the distribution of local anaesthesias?

Block and infiltration

Answer 239

• Block : deposited beside the nerve trunk
• infiltration : deposited around the terminal branches of the nerves

Question 240

What is the mechanism of action of local anaesthesias in pain control? (3)

Answer 240

• bind to sodium channels in nerves blocking it and preventing the influx of sodium
• this blocks the action potential generation and propagation
• block presists according to the number of Na channels blocked

Question 241

What nerve fibre’s are most susceptible to LA? and why

Answer 241

• A-delta and C fibres
• they have fewer sodium channels per unit area and a small diameter
• therefore nerves mediating pain and thermal stimuli are easily blocked

Question 242

What are the consistuents of LA?

Answer 242

• Aromatic region - hydrophobic
• Ester/amide bond - anaesthetics part
• Basic amine side chain - hydrophilic

Question 243

Name ester anaesthetics? (2)

Answer 243

• benzocaine
• procaine

Question 244

Name amide anaesthetics? (4)

Answer 244

• lignocaine
• prilocaine
• articaine
• bupivicaine

Question 245

What is the maximum dose of lignocaine?

Answer 245

• 2% lignocaine HCL + 1:80,000 adrenaline
• max dose is 4.4mg/kg

Question 246

What is the max dose of articaine?

Answer 246

• 4% articaine 1:100,000 adrenalin
• 7mg/kg

Question 247

Give 6 methods for removing fractured posts

Answer 247

• ultrasonic vibration
• use of masserann kit
• eggler post removal
• sliding hammer
• cut out for fibre post

Question 248

What are the temporary/immediate options for replacing a fractured tooth crown from the roots? (4)

Answer 248

• provisional over denture
• provisional post crown
• vacuum formed splint with replacement tooth
• adhesive cantilever bridge with fractured crown as pontic (use composite)

Question 249

What may be used to cement a post? (5)

Answer 249

• composite resin luting cement
• Glass ionomer luting cement
• RMGI luting cement
• zinc phosphate resin
• polycarboxylate resin

the choice of luting cement depends on the material of the post

Question 250

What are the clinical signs of erosion? (6)

Answer 250

• loss of enamel surface texture and detail
• exposed dentine and cupping of the occlusal and incisor surfaces
• bilateral concave lesions that do not appear chalky due to acid decalcification
• translucent incisal edges that may appear dark
• restorations stand proud and usually polished
• no tooth staining is present

Question 251

What occlusal records you need to check in toothwear?

Answer 251

• freeway space should be assessed
• record the OVD and resting face height
• dento-alveolar compensation
• record overbite and overjet
• stable contacts in ICP
• tooth contacts in excursive movement

Question 252

What are the causative factors of erosion? (4)

Answer 252

• chemical process due to acid that does not involve bacterial action
• causes can be intrinsic or extrinsic
• intrinsic :
  
  • GORD
  • bulimia
  • hiatus hernia
  • xerostomia
• extrinsic
  
  • acidic carbonated drinks
  • acidic fruits
  • acidic sweets
  • drugs
  • energy drinks

Question 253

How is erosion managed? (4)

Answer 253

• investigate causative factor such intrinsic or extrinsic and treat underlying problem
• apply **fluoride varnish for sensitivity **
• advice on ** use of fluoride sensitive toothpaste and mouthwash for protection **
• Dietary management - Diet diary and dietary habits

Question 254

How to manage reversible pulpitis?

Answer 254

• remove causative agents such as
  Caries
  Deep restorations - place liner
  Use desensitising agents
• follow up to check if inflammation resolved and symptoms cleared out

Question 255

What are the typical signs of reversible pulpitis?

Answer 255

• pain on cold - lasts short period after stimuli removed
• pain to sweets - lasts long periods after stimulus removed
• no change in blood flow
• Carious lesion or deep restoration is present

Question 256

What is symptomatic irreversible pulpitis?

Answer 256

• inflamed pulp that causes constant pain that keeps the patient awake at night, can be initiated hot or cold stimulus and pain does not resolve after stimuli is removed
• treated with pulpectomy and RCT / extraction

Question 257

List the signs and symptoms of irreversible symptomatic pulpitis? (7)

Answer 257

• sharp pain upon thermal stimulus
• increase in pulpal blood flow
• lingering pain after stimulus removed
• constant or intermittent pain that keeps the patient awake at night
• Spontaneous pain
• referred pain that is poorly localised
• analgesics do not work for pain relief

Question 258

What are the causative factors of irreversible pulpitis? (3)

Answer 258

• deep caries into pulp
• extensive restorations
• fractures exposing pulpal tissues

Question 259

What are the characteristics of an ideal post?

Answer 259

• parallel - more retentive than tapered (avoids wedging)
• Non threaded (passive) - smooth surface leads to less stress on remaining tooth structure
• Cement retained - less retentive than threaded but cement can act as a buffer between masticatory forces and post/tooth

Question 260

How to increase bond strength of a non threaded post?

Answer 260

• Sand blast to increase surface area

Question 261

What is the difference between threaded and non threaded posts in terms of stress to tooth?

Answer 261

• threaded causes more stress to the tooth structure unlike non threaded which are passive

Question 262

How can a post be assessed for suitability

Answer 262

• By examining the canals as it should be avoided in curved canals and should be placed in the widest canal
• Only one canal should be used in a multi-rooted tooth (straight, wide canal)
• Tooth type
• presence of ferrule
• sufficient alveolar bone support
• root filling length (4-5mm should be left)

Question 263

How does the tooth type can affect the indications of posts?

Answer 263

• Canines and incisors > posts not necessary if adequate coronal dentine is present
• Avoid in mandibular incisors as root are thin, **tapered and mesiodistal **
• Premolars - small pulp chamber and tapering root so place in widest canal

Question 264

Why should posts be avoided in curved canals? (1)

Answer 264

• to avoid perforations

Question 265

What should be a post width?

Answer 265

• no more than 1/3 root width at narrowest point
• 1mm of circumferential coronal dentine is required

Question 266

What are the ideal dimensions of a ferrule for placing a post?

Answer 266

at least 1.5mm width and height of circumferential dentine

Question 267

Give 3 core materials

Answer 267

Composite
Amalgam
GIC

Question 268

What to check in outline form modification during cavity preparation? (3)

Answer 268

• Enamel finishing
• Occlusion
• suitable restorative material

Question 269

What to check in internal cavity preparation?

Answer 269

• internal line and point angle
• cavosurface angle
• requirements of the restorative material

Question 270

What are the different types of dentine and how to do they affect binding?

Answer 270

*Primary dentine- good bonding
^ laid down during development by primary odontoblasts and have open tubules
*secondary dentine - sufficient bonding
^ laid down during function
* tertiary dentine - poor bonding
^ reactionary laid down due to mild stimuli and reparative laid down due to intense stimuli have poorly organised and sclerosed tubules

Question 271

What is the inorganic content percentage in dentine?

Answer 271

• 70% calcium hydroxyapatite

Question 272

What is the setting reaction for normal and copper enriched amalgam?

Answer 272

normal = y + hg -> y + y1 + y2
Copped enriched = y2 + AgCu = Cu6Sn5 + y1

Question 273

What changes have been made to modern amalgam to improve it ?

Answer 273

• has high copper content by adding silver copper particles to silver tin lathe cut particles

Question 274

What is the function of copper in copper enriched amalgam?

chemically

Answer 274

• it reacts with tin to reduce the availability of tin for y2 phase

Question 275

Why is zinc not used in modern day amalgam?

Answer 275

because it reacts with water and form slag causing a poor marginal seal

Question 276

What are the advantages of amalgam?

Answer 276

• longer lasting
• cheaper
• easy to handle and less finishing
• have high hardness, compressive strength and abrasion resistance

Question 277

Why y2 amalgam is not as good as copper enriched amalgam?

Answer 277

• low abrasion resistance
• poor strength

Question 278

What are the disadvantages of amalgam (4)

Answer 278

• does not bond chemically to the tooth
• extensive tooth preparation required
• Creep
• allergies to metal
• not biocompatible
• does not set on demand
• amalgam tattoo
• poor aesthetics
• cannot be used on children under 15 and breast feeding/preganant women
• mercury toxicity

Question 279

What percentage of maxillary first molars have a second mesiobuccal canal?

Answer 279

• 93% have 4 canals
• 7% have 3 canals

Question 280

What are the 3 design objectives in endodontics?

Answer 280

• Create a continuously tapering funnel shape
• Keep apical foramen in original position
• Keep apical constriction as small as possible

Question 281

Access cavities for endodontic treatment

Answer 281

Question 282

What are the advantages of the crown down technique?

Answer 282

• removes bulk of infected tissue allowing for a reservoir for irrigant
• Keeps reference point for working length
• makes straight line access easier
• Reduced instrument stress -> less instrument separation
• limits the spread of infection at the apical foramen

Question 283

What is the irrigation protocol after shaping the canal ?

Answer 283

EDTA 17% for 1 minute
NaCL 3% for 10 minutes 30ml
slow injection using index finger

Question 284

What is gradual curvature? and abrupt curvature of the canal?

Answer 284

• gradual curvature is when a canal is curved and iso 10 file goes to working length without pre-curving it
• abrupt curvature if the an iso 10 file does not go to the full working length only when it is pre-curved

Question 285

Name 3 laws of pulpal floor anatomy?

Answer 285

• law of colour : always darker
• law of symmetry 1 = orifices lie equidistant to an imaginary mesiodistal line through the pulp chamber (except maxillary molars)
• law of symmetry 2 = orifices lie perpendicular to a mesiodistal line through the pulp chamber (except maxillary molars)

Question 286

Give 3 rules for locating orifices in the pulpal floor

Answer 286

• always at the junction of the floor and wall
• always at angle of floor and wall junction
• always at terminus of developmental fusion lines

Question 287

Give 4 reasons for irrigation during endodontic treatment?

Answer 287

• disinfect the root canals
• dissolve organic debris and flush out debris
• to lubricate root canal systems
• remove endodontic smear layer

Question 288

Why is sodium hypochlorite a good irrigant?

Answer 288

• high antimicrobial activity
• dissolves organic pulp necrotic tissue
• disrupt the smear layer
• dissolves pulp remnants and collagen

Question 289

What strength of NaoCl is used in the root canal system?

Answer 289

3%

Question 290

Name another irrigant used in endodontics other naocl?

Answer 290

Chlorhexidine digluconate
EDTA

Question 291

How is the smear layer removed ?

Answer 291

• using EDTA 17% for 1 minute which is a chelating agent that is capable of removing the smear layer
• it opens the dentinal tubules allowing sealer and irrigant penetration

Question 292

Name 2 intracanal medicaments and state their use

Answer 292

• Antimicrobial paste (ledermix) :
  reduce pulpal inflammation
• non setting calcium hydroxide:
  antibacterial effect
  reduce inflammation
  reduce bacterial load
  removes tissue debris

Question 293

What are the indications of a resin retained bridge?(5)

Answer 293

• Young teeth as it is less destructive
• Good enamel quality
• large surface area for bonding in abutement tooth as wing need to be 0.5 supragingivally
• Good for replacing single missing tooth
• Minimal occlusal load

Question 294

What are the contraindications for a resin retained bridge? (6)

Answer 294

• insufficient or poor quality enamel
• high occlusal load
• limited bonding area on abutment teeth
• long spans
• Gingival recession and hard tissue loss
• tilted or malpositioned teeth

Question 295

Which cement for a porcelain bridge? (fixed)

Answer 295

Nexus (dual cure resin cement)

Question 296

Which cement for an adhesive resin retained bridge?

Answer 296

Panavia 21 (10-MDP)

Question 297

what to cement an all metal bridge ?

Answer 297

• Aquacem (GIC)
• relyx (RMCIC)

Question 298

When is a dual cure cement indicated?

Answer 298

• when cementing a thick indirect restoration that light cannot penetrate it

Question 299

Where is silane coupling agent used?

Answer 299

• bonds resin to filler in composite resin
• bonds etched porcelain to resin cements

Question 300

Describe chemically how silane coupling agent work

Answer 300

• it is a bivalent molecule meaning it have a hydrophobic and a hydrophilic end
• the hydrophilic end bonds with porcelain and the hydrophobic ends bonds with the resin luting cement

Question 301

Describe the appearance of attrittion? (4)

Answer 301

• lesions on occlual and incisal surfaces
• flattening of incisal edges
• reduction of cusp height and flattening of inclined teeth planes
• Wear on restorations

Question 302

Describe the appearance of abrasion (4)

Answer 302

• labial/buccal and cervical lesions on premolars and canines
• V shaped or rounded lesions
• notching of incisal edge
• Sharp margin at enamel edge where dentine is worn preferentially

Question 303

Describe the appearance of abfraction

Answer 303

• wear at cervical margin shows as V shaped due to eccentric occlusal forces leading to compressive and tensile stress on the cervical margins

Question 304

How may toothwear be monitored? (3)

Answer 304

• using BEWE or night a smith index
• using study models
• using clinical photographs

Question 305

What percentage of adults have toothwear?

Answer 305

77% have some form of tooth wear anteriorly involving dentine

Question 306

Give 4 intrinsic and extrinsic causes of tooth discolouration?

Answer 306

Intrinsic
- fluorosis
- tetracycline
- non vital teeth
- amalgam restorations
- systemic disease such as porphyria (red) and cystic fibrosis (grey)
Extrinsic
- smoking
- tannins (coffee and tea)
- chlorhexidine
- chromogenic bacteria
- iron supplements

Question 307

How does vital bleaching with hydrogen peroxide works? (3)

Answer 307

• Discolouration may be caused by chromogenic long chain molecules that are chemically stable
• Hydrogen peroxide breaks down these molecules into smaller ones which are less pigmented (lighter in colour)
• It breaks them down by oxidising them (ionic exchange)

15-35% for chairside bleach

Hydrogen peroxide exceeding 0.1% cannot be used on patients under the age of 18 unless for preventing or treating disease

Question 308

What is the common active ingredient in tooth whitening bleach and how is it related to hydrogen peroxide (at home)?

Answer 308

Carbamide peroxide 10% , this breaks into hydrogen peroxide and urea which oxidises chromogenic molecules and lead to a lighter colours

3% hydrogen peroxide = 10% carbamide peroxide

Question 309

Give 4 risks of vital bleaching

Answer 309

• Gingival irritation
• Tooth sensitivity
• Effect can wear off
• spillage of bleaching agents

Question 310

What is the procedure of vital bleaching?(home bleaching)

Answer 310

• brush tooth
• apply bleach gel to tray
• seat tray and push and remove excess
• rinse mouth gently
• wear overnight for at least 2 hours
• remove with brush and cold water
• use for 3-6 weeks until effect is shown

windows in tray should be cut on teeth that are not bleached

Question 311

Why is it not advised to use bleaching agents on people under the age of 18?

Answer 311

• May cause increased sensitivity due to higher permeability of dentine and enamel

Question 312

What are the key features of a cavity for composite? (3)

Answer 312

• no unsupported enamel
• no sharp internal line angles
• Bevel cavo-surface margins to increase bonding

Question 313

Give 3 reasons for instrumenting the root canal system (4)

Answer 313

• remove infected soft and hard tissue
• create reservoir for irrigants in canal space
• create space for medicaments and obturation
• retain integrity of radicular structures

Question 314

What is the Protaper sequence

Answer 314

• Use 10,15 K files to explore canal and ensure straight line access (stopper at corrected working length)
• Use S1 file to prepare coronal third
• determine corrected working length using apex locator or radiograph
• ensure straight line access again using 10,15 K files to corrected working length
  *Use S1 file again for apical third
• prepare middle third of canal using S2 file
• then use F1 for the apical third
  Sequence (S1, S2 , F1 )

Use the balanced force technique

Irrigate in between of each file to flush out debris

Question 314

What advantages do pro-taper (NiTi) files have over K files? (6)

Answer 314

• Good shape memory
• easier to use
• more cutting efficacy
• super-elasticity
• decreased risk of edging due to decreased lateral pressure
• less instrument numbers are needed

Question 315

Name other rotary systems other than protaper?

Answer 315

• reciproc
• Protaper gold

Question 316

Name and describe 2 other motions for files other than reaming and filing?

Answer 316

• watch winding : back and forth movement (30-60 degrees)
• balanced force : 1/4 CW turn then CCW 1/2 turn

Question 317

Name 3 reasons a file may separate? (3)

Answer 317

• flexural stress (repeated cyclic fatigue)
• Torsional stress (binding to canal wall)
• Complicated curved canal (non straight line access)

Question 318

Describe reaming and filing

Answer 318

• reaming - clockwise motion and apical pressure
• Filing - push and pull motion

Question 319

Advantages of K files (4)

Answer 319

• cost effective
• good canal exploration
• achieve apical patency
• determines curvature

Question 320

Draw and label posselt’s envelope

Answer 320

E - edge to edge
RCP - retruded contact position
ICP - intercuspal contact position
Pr - protrusion of mandible
R - max mandibular opening position when with no condylar translation (rotating condyles)
T - Max mandibular opening with full condylar translation

Question 321

Describe the path of RCP-ICP

Answer 321

• It can be termed as a slide which have a vertical, lateral and horizontal components

The lateral component of this slide cannot be seen at saggital view

Question 322

What is Hanau’s quint?

Answer 322

It includes five factors that may affect occlusal balance
* condyle guidance angle in saggital plane
* incisal guidance
* compensating curves
* cuspal height
* inclination of occlusal plane

Question 323

What is the thickness of shim-stock and articulating paper?

Answer 323

Articulating paper > 20 um with miller forceps
Shim stock > 8um with mosquito forceps

Question 324

What is the average biological width?

Answer 324

2mm (connective tissue 1mm ; junctional epithelium 1mm)

the combined height of the connective tissue attachment and the epithelial attachment above the alveolar bone

Question 325

How can amalgam overhangs be avoided? (3)

Answer 325

• adequate condensation of amalgam
• using wedges between teeth
• correct matrix adaptation

Question 326

What problems may occur due to overhangs? (2)

Answer 326

• can act as a plaque and food trap - causing caries, gingivitis and periodontal disease
• can lead to restoration fracture ( if it is a thin section)

Question 327

How do you manage overhangs? (2)

Answer 327

• Replace restoration
• Repair using high speed or soflex discs

Question 328

Give 4 functions of a facebow?

Answer 328

• Transfer the relationship between the maxillary teeth and the axis of rotation of the condyles from the patient mouth to an articulator
• Transfer the angulation of maxillary occlusal plane in relation to the horizontal reference plane
• Replicates the patient mandibular movements to be transferred to an articulator for treatment planning of indirect restorations
• Aid in accurate diagnosis by providing a reference for evaluating the patient occlusion

Question 329

Why anterior guidance is preferred to posterior guidance? (4)

Answer 329

• easier to produce
• easy on muscles
• protect teeth and posterior restorations
• disculsion of posterior teeth during mandibular lateral movements

Anterior guidance is when mandible are guided by teeth
Posterior guidance is when mandible is guided by condylar movements

Question 330

What are the ideal properties of a denture base? (7)

Answer 330

• dimensionally accurate
• easy to manufacture and repair
• high abrasion resistance and hardness
• high transverse, impact and fatigue strength
• high softening temperature
• high thermal conductivity
• biocompatible

Question 331

What are the consistuents of PMMA

Answer 331

• powder
  benzoyl peroxide (initiator)
  PMMA particles
  Plasticisers
  Co-polymer
• Liquid
  methacrylate monomer (polymerises)
  Co-polymer
  hydroquinone (inhibitor)

Remeber the powder as 4P’s

Question 332

Give 4 possible faults while manufacturing acrylic and why does it occur?

Answer 332

• contraction porosity - too much monomer , insufficient excess material, insufficient pressure
• Gaseous porosity - monomer boiling in bulkier parts of the denture
• Granularity - too little monomer
• Crazing - fast cooling rate causing internal stresses

Question 333

What are the principles of tooth preparation for crowns (6)

Answer 333

• Preservation of tooth structure - avoid weakening tooth structure and damaging the pulp
• retention and resistance -
  1. Retention prevents removal of restoration along the path of insertion or long axis of tooth
  2. Resistance - prevents dislodgment due to forces directed in an apical or oblique direction and movement of restoration under occlusal load
• structural durability - enough bulk to withstand forces of occlusion
• marginal integrity - to minimise microleakage
• preservation of the periodontium - smooth margins to ensure OH
• aesthetic considerations - if at smile line

Question 334

How to decide on tooth crown preparation in tooth structure conservation?

Answer 334

balance between resistance , retention and structural durability

Question 335

What happens when under preparing a tooth for a crown? (3)

Answer 335

• poor aesthetics
• occlusion consequences
• periodontal consequences

Question 336

What happens when overpreparing a tooth for a crown? (2)

Answer 336

• pulp damage
• tooth strength compromised

Question 337

How to achieve retention in crown prep? (2)

Answer 337

• limiting the number of paths of insertion
• grooves and slots

Question 338

What is the ideal inclination of crown walls?

Answer 338

6 degrees

Question 339

Why is length of walls important in crown preparation?

Answer 339

prevents tipping displacement (longer walls are better)

Question 340

When is the path of insertion of crown prep determined?

Answer 340

before preparation begins

Question 341

How is structural durability achieved in crown prep? (3)

Answer 341

• occlusal reduction
• axial reduction
• functional cusp bevel

Question 342

How to achieve marginal integrity in crown prep?

Answer 342

By preparing finish line configurations to reduce microleakage such as chamfer or shoulder

Question 343

What are the types of finish line configurations in crown prep (5)

Answer 343

• knife edge
• bevel
• chamfer
• shoulder
• beveled shoulder

Question 344

How should margins of the crown preparation be to preserve the periodontium? (3)

Answer 344

• should be smooth and fully exposed to cleansing action
• should be placed where the dentist can finish them and patient can clean them
• placed at gingival margin whenever possible

Question 345

What are the stages of crown preparation? (6)

Answer 345

• Occlusal reduction - fissure bur or rugby ball
• Separation - long tapered bur
• Buccal reduction - shoulder bur
• Lingual or palatal reduction - chamfer bur
• Shoulder and chamfer finish - shoulder bur
• check occlusal surface and clearance - in ICP and excursive movements

Question 346

What considerations during occlusal reduction of a crown?

Answer 346

• retain some occlusal morphology
• consider thickness of metal and porcelain
• check occlusal clearance

Question 347

What degree of taper is ideal in separation? (crown prep)

Answer 347

5-10

Question 348

In how many planes should you prepare buccal aspect in crown prep?

Answer 348

2 planes (apical and coronal)

palatal/lingual is completed in one plane - follow palatal contour for anteriors and canines

Question 349

What structure should you avoid when preparing a crown prep (buccal)

Answer 349

pulp horns

Question 350

What is the most common reason lab cannot construct crown?

Answer 350

insufficient occlusal clearance

Question 351

Reduction dimesions for crowns

Answer 351

Question 352

Give advantages of CoCr metal base? (5)

Answer 352

• higher dimensional stability in comparison with acrylic (does not change shape easily)
• Stable and retentive
• High thermal conductivity - allows patient to feel temperature
• More hygienic - less porous which decreases accumulation of food, plaque and calculus
• Can be thin but still maintains strength

Question 353

What are the ideal properties of impression materials? (6)

Answer 353

• low setting shrinkage
• low viscosity - flows readily
• surface wetting ability - make intimate contact with teeth and mucosa
• small contact angle - ensure all surfaces are replicated (no space between globules)
• low thermal expansion and contraction
• 50um - 70um surface reproduction - ensure accuracy

Question 354

Name 4 non -elastic impression materials

Answer 354

• impression compound
• zinc oxide eugenol
• impression wax
• impression plaster

Question 355

Name 4 elastomer impression materials?

Answer 355

• Polysulphides
• Polyether - Impregum
• Addition curing silicone - aquasil ultra
• Condensation curing silicone - Verone

Question 356

Name 2 hydrocholloid impression materials

Answer 356

• agar - reversible
• alginate - irreversible

Question 357

What is the setting reaction for alginate?

Answer 357

Sodium alginate -> Calcium alginate

Question 358

Give 2 advantages of alginate

Answer 358

• easy to use
• non toxic and non irritant
• adeqaute detail recording
• adequate setting time

Always remember (easy to use might go as answer for many things)

Question 359

Give 2 disadvantages of alginate?

Answer 359

• poor tear strength
• limited dimensional stability - should be placed in moisture as it is susceptible to dehydration and shrinkage
• Single use

Question 360

Give uses of alginate (3)

Answer 360

• Primary impressions for complete/RPD
• Impression for indirect restoration
• wound and burn dressing

Question 361

Give advantages of other elastomeric impressions over alginate? (6)

Answer 361

• higher reproduction of surface details
• higher elastic recovery
• higher tear strength - reduce risk of tearing margins
• higher dimensional stability - does not deform
• lower rigidity - easier removal from undercuts
• lower viscoelasticity

Question 362

What is the composition of GI?

Answer 362

Acid - polyacrylic acid and tartaric acid

**Base **
Quartz
Aluminia
Aluminium phosphate
Aluminium flouride
Calcium fluoride
Sodium fluoride

Question 363

Describe the setting reaction of GI

Answer 363

• acid base reaction: glass + acid -> salt and silica gel
• Consist of 3 phases :
  Dissolution - acid dissolves glass particles releasing ions
  Gelation - formation of calcium polyacrylate matrix leading to initial set and early strength
  Hardening - aluminium cross-linking leading to increased strength, final set and fluoride release

Question 364

Give 5 uses of glass ionomer

Answer 364

• core build up for crown
• indirect restoration cementation
• cervical restorations due to poor moisture control
• temporary restoration
• fissure sealant for uncooperative children

Question 365

Give 6 properties of glass ionomer?

Answer 365

• Fluoride release
• low shrinkage (no contraction on setting)
• cheap
• chemically bonds to tooth
• long term stability with low micro-leakage
• relatively insoluble once fully set

Question 366

Give 4 disadvantages of GI?

Answer 366

• brittle with poor wear resistance
• moisture susceptible when first placed
• poor aesthetics
• poor handling characteristics

Question 367

What is a knife edge ridge?

Answer 367

It is a class of alveolar ridge that is resorbed laterally (labial/buccal - palatal/lingual)

Question 368

Name three causes of a knife edge ridge?

Answer 368

• periodontal disease before extractions
• traumatic surgical extraction
• immediate dentures

Question 369

How can knife edge ridge be managed for complete dentures? (4)

Answer 369

• Apply soft lining on fitting surface of denture
• Surgery to remove sharp bone if causing pain (alveoloplasty)
• relief areas on the denture over painful areas
• Use functional impression technique

Question 370

What is the difference between soft lining and tissue conditioner?

Answer 370

• Soft lining can be used on healthy mucosa as a shock absorber or cushion in relining a denture or for knife-edge ridges , it is a long term management
• Tissue conditioner is used in unhealthy or ulcerated mucosa to aid healing and dissipate forces and is a short term management

Question 371

What is a functional impression?

Answer 371

• it is an impression taken during function
• it can be used for relining dentures
• it can be used for short term refining

procedure may involve pt wearing denture + tissue conditioner 24 hours

Question 372

Define retention and stability of a denture?

Answer 372

• retention - the resistance to vertical displacement
• stability - resistance to lateral displacement

Question 373

How is an upper complete denture retained? (4)

Answer 373

• Muscles
• Extension to buccal sulcus and peripheral seal
• Adhesion and cohesion
• Post dam position

Question 374

Other than remaking how can you improve retention of a dentures? (4)

Answer 374

• relining
• rebasing
• implant retained
• precision attachements

Question 375

What are the indications of replica dentures? (3)

Answer 375

• Pt satisfied with current denture but need some improvements
• replacement of successful immediate denture
• Worn denture

Question 376

How to restore freeway space in a very worn denture? (2)

Answer 376

• use occlusal pivots to stabilise occlusion then make new dentures
• Restore occlusal surface with self curing acrylic resin

Question 377

Describe the process of making a replica denture (9)

Answer 377

• disinfect current denture
• modify denture with green stick if any under-extensions is present
• choose trays and place adhesive
• take impression of dentures outside the patient mouth using lab putty
• remove dentures and give to patient
• Send lab ask to make replica record blocks (shallac base)
• next visit take master impressions (use light body) and jaw registration using replica blocks
• send to lab to mount on articulator and ask for wax trail for try in
• try in and if happy ask lab to finish denture in acrylic

Question 378

Denture anatomy

Answer 378

Question 379

What problems can an incorrect OVD cause?

Answer 379

• TMJ problems
• clicking on teeth when eating
• Angular cheilitis
• Occlusal trauma
• pain in mandibular muscles

Question 380

Where is the post dam?

Answer 380

• extending from the hamular notch on side to the hamular notch on the other side along the vibrating line which is the junction between the soft palate and the hard palate

Question 381

Where is the post dam located in regards to the palatine fovae?

Answer 381

1-2mm anteriorly

Question 382

where is the distal extension of a lower complete denture?

Answer 382

2/3 into the retromolar pads

Question 383

Why is the buccal shelf used for support?

Answer 383

• because it is a non resorbable region which can provide adequate support

Question 384

What anatomical features help set the incisors?

Answer 384

• facial symmetry and philitrum for midline
• incisive papilla (1cm anterior to it
• Lip line - 1-2mm of incisal edge show at rest
• frenulum?

Question 385

What 4 things make up the shade of teeth?

Answer 385

• chroma - saturation of the color
• Hue - color
• translucency - how much light pass through
• value - how much light reflects

Question 386

3 ways to measure OVD

Answer 386

• dividers
• ruler
• willis bite gauge

Question 387

Give the average horizontal bone loss for
incisors
canines
premolars
molars

Answer 387

incisors - 6mm
canines - 8mm
premolars - 10mm
molars - 12mm

Question 388

What is the difference between horizontal and angular bone loss?

Answer 388

• horizontal bone loss is the loss of height of the crystal bone around the tooth due to plaque destruction it is usually seen as symmetrical bone loss
• angular bone loss is due to plaque accumulation on one side of the tooth causing scalloping resulting in a vertical/angular bone loss pattern

Question 389

How is angular periodontitis caused?

Answer 389

• due to localised plaque retention causing inflammation in the PDL space
• this can also be caused by poor oral hygiene and lack of interdental cleaning

Question 390

Define generalised and localised bone loss?

Answer 390

Generalised - affecting more than 30% of sites
Localised - affecting less than 30% of sites

Question 391

Define mild moderate and severe bone loss

Answer 391

• mild is more than 30%
• moderate is 30-50%
• Severe is more than 50%

Question 392

What are the advantages of immediate dentures? (4)

Answer 392

• allows patient to have dentures as soon as possible after extractions (maintain aesthetics and have psychological effect)
• prevent soft tissue collapse
• maintains muscle tone
• Can act as a haemorrhage control
• Reduce extraction post op pain ( protects pockets)

Question 393

What are the disadvantages of an immediate denture? (4)

Answer 393

• Can cause pain during tissue swelling after extraction
• Need to be remade/rebased/reline - becomes loose due to bone resorption post extraction
• Can cause knife edge ridge
• Can be ill fitting right after an extraction

Question 394

Write a prescription for upper/lower complete denture special tray

Answer 394

Primary impression -> special trays
please construct upper and lower special trays in light cured acrylic for complete dentures with 1mm spacer for lower 2mm spacer for upper , please include intra oral handles

Question 395

What is the difference between generalised and localised aggressive periodontitis?

Answer 395

Generalised - affect 3 other teeth other than the incisors and first molars with generalised loss of attachement
Localised - affect first molars and incisors with localised loss of attachment

Question 396

What is the new periodontal classification (2018)

Answer 396

Question 397

AAP CLASSIFICATION 2018

Answer 397

periodontal health, gingival disease and conditions
1. Healthy periodntium and gingival tissue
2. plaque induced gingivitis
3. non plaque induced gingivitis
periodontitis
4. necrotising periodontal disease
5. periodontitis
6. periodontal disease as a manifestation of systemic disease
other conditions affecting the periodontium
8. systemic diseases or conditions affecting the periodontal supporting tissue
9. periodontal abscess and endodontic-periodontal lesions
10. mucogingival deformities and conditions
11. traumatic occlusal forces
12. tooth and prosthesis related factors

Question 398

What bacteria is usually involved in periodontitis?

Answer 398

• P.gingivalis
• A. actinomycetemcomtians

Question 399

What things are recorded in a periodontal pocket chart ? (8)

Answer 399

• furcation involvement
• tooth mobility
• plaque index
• bleeding on probing
• loss of attachment
• missing teeth
• pocket depth
• degree of gingival recession

Question 400

How is mobility graded?

Answer 400

0 - physiological movement 0 - 0.2 mm
1 - less than 1mm horizontal movement
2 - 1-2 horizontal movement
3 - more than 2 horizontal and vertical movement (rotation and depression)

Question 401

How is furcation graded?

Answer 401

1 - less than 3mm horizontal
2 - more than 3mm but not through through
3 - through through

Question 402

How is gingival recession graded ?

Answer 402

Using miller classification

Question 403

Give 2 disadvantages of a pocket chart

Answer 403

• probing depth may vary from one operator to another
• True pocket may not be measured accurately if there is sub-gingival calculus blocking it
• Assumes all patient have same root length so it may appear worse than actual disease

Question 404

What are the local causes of gingival recession? (9)

Answer 404

• smoking
• high frenal attachments
• Poor marginal restorations
• Fixed orthodontic appliances
• Abrasive toothpaste
• parafunctional habits
• Periodontitis
• Trauma by tooth brushing
• crowding
• traumatic overbite

Question 405

Special investigations to measure recession?

Answer 405

• 6PPC
• Study models
• Clinical photographs

Question 406

How is localised recession managed?

Answer 406

• Address underlying condition such as parafunctional habits and traumatic toothbrushing and give instructions
• Address and manage risk factors such as smoking and periodontal disease
• Manage sensitivity by applying fluoride varnish, using sensodyne toothpaste, seal and bond and fluoride varnish
• Surgery

Question 407

What types of surgeries are used to manage gingival recession

Answer 407

• Free soft tissue graft from palate
• coronal advancement flap in severe cases
• tunnel preparation technique

Question 408

What are the modified systemic factors that can cause periodontitis? (7)

Answer 408

• smoking
• stress
• hormones - pregnancy, puberty
• Drugs
• Diabetes
• cardiovascular disease
• Obesity - due to poor diet and lifestyle

Question 409

What drugs might cause gingival hyperplasia?

Answer 409

• Phenytoin : anti-epileptic
• Amlodipine : Ca channel blocker
• Cyclosporine : immunosuppressant

Gingival hyperplasia may cause periodontitis

Question 410

What are the defect systemic factors that may cause periodontitis?

Answer 410

• monogenetic syndromes such as
  Sickle cell anaemia
  Cystic fibrosis
  Polycysytic kidney disease
• Down’s syndrome

Question 411

Why is diabetes a risk factor for periodontal disease? (4)

Answer 411

• It causes impaired wound healing
• heightened inflammatory response
• Alters collagen production (decreased)
• Causes microangiopathy
• xerostomia and increased sugar in saliva leading to increased plaque

Question 412

Describe how diabetes affect the periodontium biologically?

Answer 412

• It leads to abnormal glucose regulation resulting in advanced glycation end products production
• these interact with surface cell receptors leading to :
  increased permeability and adhesion molecules of endothelial cells
  increased chemotaxis
  production of IL-6 and TNF -alpa by macrophages
  increased MMP
  and decreased collagen production by fibroblasts

results in impaired wound healing and heightened inflammatory response

Question 413

What tests are carried out for diabetes and diabetic control? (4)

Answer 413

• fasting glucose test
• blood glucose home testing kits
• HbA1c
• glucose tolerance test

Question 414

What is the ideal value for HbA1c test in diabetic patients and how often is it carried out?

Answer 414

48 mmol/mol (6.5%) or below every 3-6 months

Question 415

How does smoking affect the periodontal tissues? (7)

Answer 415

• staining
• xerostomia
• gingival recession
• increases disease anteriorly
• reduced bleeding on probing
• halitosis
• hyperkeratosis

Question 416

What is interleukin-1?

Answer 416

• It is a highly pro-inflammatory cytokine produced by immune cells
• It regulates the immune response

Question 417

What are the aims of periodontal step 1 ?

Answer 417

• Build the foundations for optimum treatment by managing risk factors and behavioral change
• reduction of gingival inflammation by removing plaque retentive factors such as calculus and overhangs

Question 418

What is the overall aim of periodontal therapy?

Answer 418

• Manage and control periodontal disease to maintain or improve periodontal tissues.
• Preserve natural dentition appearance and function and improve patient overall oral health and well-being

Question 419

How is step 1 provided?

Answer 419

• Patient education about their periodontal disease status + risks and importance of prevention and treatment
• building patient motivation and compliance to perform daily oral hygiene and control risk factors
• oral hygiene instructions
• Clinical crown supra and subgingival PMPR

Question 420

Name the causes of gingival hyperplasia?

Answer 420

• Systemic disease - granulomatous disease, Leukaemia, fibroma, giant cell granuloma
• Drug induced - phenytoin, amlodipine, cyclosporine
• conditioned enlargement due to pregnancy or puberty, vitamin C deficiency

Question 421

What is the classic pattern of gingival hyperplasia?

Answer 421

*Starts at the interdental papilla and develop to include the entire attached mucosa

Question 422

How does gingival overgrowth influence periodontal disease?

Answer 422

• difficult plaque control
• increase pocket depth
• increases inflammation due to the oedematous inflammatory component

no evidence of gingival overgrowth as a predisposing factor

Question 423

How is gingival overgrowth managed / with periodontal disease?

Answer 423

• Step 1 perio
• Surgical interventions : gingivectomy, gingivoplasty
• Consult with GMP to discuss change of medication
• Regular monitoring

Question 424

Examples of developmental bone pathologies?

Answer 424

• Tori - benign bone growth in mouth (mandibular tori)
• Fibrous dysplasia - fibrous tissue replace bone

Question 425

Examples of inflammatory bone pathologies?

Answer 425

• Dry socket (alveolar osteitis)
• Osteomyelitis (bone infection)

Question 426

Examples of neoplasm bone infection

Answer 426

• Osteoma (benign tumour made of bone)
• Osteosacroma (bone cancer)
• Osteoblastoma ( bone destoryed and replaced by weaker tissue )

Question 427

Examples of metabolic bone pathologies?

Answer 427

• Osteoporosis (weakened bones)
• Paget’s disease (bone expansion and weakening)

Question 428

Give 4 differential diagnosis for a multilocular radiolucency?

Answer 428

• Ameloblastoma
• Giant cell granuloma
• Odontogenic myxoma
• Odontogenic keratocyst
• Cherubism (abnormal bone tissue in the bone)

Question 429

What is the reason for distorted anterior teeth in a radiograph?

Answer 429

Patient not in the focal plane (patient too forward in the machine)

Question 430

What is the reason of a blurry image on radiograph?

Answer 430

Patient moving during exposure

Question 431

What causes an image to be too wide on a radiograph?

Answer 431

Patient too far back in the machine (patient canine behind machine canine line)

Question 432

How to limit radiographic positioning errors? (4)

Answer 432

• use chin rests
• use bite blocks between incisors
• use hand rests to prevent movement
• correct positioning of guide lines : canine, centreline, frankfort plane

Question 433

What are the characteristics of ghost images on a radiograph?

Answer 433

• Higher due to vertical beam angulation (-8)
• Horizontally magnified and distorted
• opposite side
• further forward - due to change in anterior posterior position

Question 434

What are the ways to reduce patient dose to radiation? (3)

Answer 434

• use E speed film (fewer x-ray photons required)
• use Kv range from 60-70 Kv with fsd of >200
• Use rectangular collimation and film holders

Question 435

What is compton scatter effect?

Answer 435

• X-ray photon interacts with outer shell electrons which is greater than the electron energy
• The electron is then ejected taking some of the photon energy which causes the photon to change direction and loose some energy
• Results in a decreased image quality

Question 436

What compton scatter and absorption depend on ?

Answer 436

• proportionate to density of material
• not affected by atomic number or photon energy

Question 437

What is photoelectric absorption effect in radiology?

Answer 437

• The photon interacts with inner shell electron which has a higher energy than the photon
• This results in the x-ray photon disappearing
• the energy difference is emitted as light as the electron is ejected as a photoelectron
• image appears white or grey depends on photon involvement

Question 438

What does photoelectric effect depends on?

Answer 438

• atomic number
  *density of material
• photon energy

Question 439

What metal is used for absorption in x-rays?

Answer 439

lead

Question 440

Why is lead used for absorption in x-rays?

Answer 440

• prevents back scattered photons
• absorbs scattered x-ray
• absorb some of primary beam
• prevent image degredation

This is due to its high atomic number and density

Question 441

Name other metals than lead that are used in x ray machine

Answer 441

Copper - heat conductor
Tungston - cathode filament
Aluminum - filtration

Question 442

Give 5 radiation safety features? regarding IRR99

Answer 442

• controlled area for radiation
• safety and maintenance checks for
• warning signs for controlled area
• sound during exposure
• light during exposure
• automatic radiation stop or when button is not held
• lights when equipment is on

Question 443

What is ALARA

Answer 443

• as low as reasonably achievable
  This is to minimise dose and exposure and keep exposure below limits whenever possible

Question 444

How is ALARA achieved?

Answer 444

• Use E speed film
• Use of film holders and rectangular collimation
• Use Kv range 60-70 and fsd more than 200
• use aluminim filtration system
• beam diameter should be no greater than 60mm at end of spacer

Question 445

Why is it advised to use E speed film or faster/direct digital film in radiation?

Answer 445

Because there will be fewer x-ray photons required = lower dose to patient

Question 446

What are IRMER2000 guidelines? ( ionising radiation medical exposure regulations)

Answer 446

• Minimising unintended , incorrect and excessive exposures
• Keeping doses in diagnostics as low as reasonably practical for their intended use (optimisation)
• Ensuring benefits outweigh risks for each exposure (justification)

Question 447

What are the three main principles of radiation protection

Answer 447

• justification
• optimisation - ALARP
• Dose limitation - for radiation workers and members

Question 448

What are the 4 personnel and roles in IRMER

Answer 448

• Employer
• Referrer
• Practitioner (IRMER practitioner)
• Operator

Question 449

What is the role of the employer in IRMER?

Answer 449

• legal person responsible for safety
• makes sure equipment is in line with regulations
• ensure staff are trained and follow these regulations

Question 450

What is the role of the referrer in IRMER?

Answer 450

• person requesting radiograph
• need to take history and do clinical examination prior to referral
• Justifies the exposure

Question 451

What is the role of the practitioner in IRMER?

Answer 451

• confirms justification and authorise exposure request
• must ensure doses are ALARP
• can be dentist, radiologist or specialist

Question 452

What is the role of the operator in IRMER?

Answer 452

• person who takes and reports the radiograph to help aid diagnosis
• notes exposure and ensure x-ray are in accordance with IRMER and ALARP

Question 453

Why should you report a radiograph? (6)

Answer 453

• to aid diagnosis
• written record of patient dentition
• aid in treatment planning
  *medico-legal reasons
• ensures best practice
• audit purposes

Question 454

What is paralleling technique in radiology?

Answer 454

• image receptor and object are parallel but not in contact
• beam is perpendicular/divergent
• image receptor and object are some distance apart but with short spacer cone
• short spacer cone allows short fsd
• requires film holder and stabilisation with cotton roll

Question 455

What is bisecting angle technique in radiology?

Answer 455

• image receptor and object are not parallel and partially in contact
• beam is perpendicular
• image receptors are close together at crown but apart at apex
• can be done without film holders
• use fsd 20cm

Question 456

How to reduce magnification when taking a radiograph with paralleling technique?

Answer 456

Use long x-ray fsd 20cm

Question 457

What factors does an implantologist consider before placing an implant ? (7)

Answer 457

• Smoking status
• Patient aesthetic demand
• Patient motivation and compliance
• Occlusion
• alveolar bone quantity and quality
• Space available for placing implant
• Periodontal status and oral hygiene
• Medical and drug history

Question 458

What bone dimensions are required for implant placement and how are they measured?

Answer 458

• 1.5 horizontal bone around implant
• 3mm between implants
• 7mm between crowns for implant placement
• 2mm space from adjacent structures such as IAN and maxillary sinus
• more than 5mm for papilla from bone crest to contact points
  ** assessed with CBCT **

Question 459

Name possible common complications for extracting a standing alone maxillary molar?

Answer 459

• OAC
• root or tooth lost in maxillary sinus
• Maxillary tuberosity fracture

Question 460

Label Condyle, hard palate, zygomatic buttress, styloid process, soft palate
hyoid bone, nasal septum, ear lobe, bite peg and ghost image

Answer 460

Question 461

Label denture bearing areas anatomy of the upper and lower arch

Answer 461

Question 462

List 3 side effects associated directly with the chronic use of cocaine on the structures in the head and neck?

Answer 462

• Numbness of the gingivae
• Erosion of the floor of the nasal cavity creating OAF/OAC
• Wear due to bruxism
• Ulceration in the gingivae

Question 463

List 2 complications in the dental surgery of local anaesthesia with adrenaline is administered to a patient who recently took cocaine?

Answer 463

• increase in heart rate - heart palpitations and loss of consciousness
• mood swings - may get aggressive

Question 464

How do you cement a porcelain bridge?

Answer 464

• Resin composite luting cement with silane coupling agent which creates covalent bond to oxide groups on the porcelain surface which is hydrophilic and hydrophobic ends react with composite

Question 465

How do you cement a metal bridge ?

Answer 465

10-MDP or 4-META

Question 466

How is the surface of pocelain treated in the lab to improve adhesion?

Answer 466

• Etched with hydrofluoric acid

Question 467

When is a dual cured cement indicated ?

Answer 467

• Cementing a thick or opaque indirect restoration that a light cure cannot penetrate

Question 468

A patient attend with a debonded cast gold post and core , give 4 reasons for a debond?

Answer 468

• Incorrect cementation material
• Contamination during cementation
• Unfavoured occlusion
• Inadequate post preparation

Question 469

Why might a core fracture from a post?

Answer 469

• Casting error
• Inadeqaute ferrule
• Trauma
• Bruxism