Restorative/DMS/ General Flashcards
Endodontic stainless steel mishapes
Ledges
blockage
perforations
transportation of apical foramen/Apical zipping
What are ledges?
ledges are internal transportation of the root canal that may be due to wrong working length or skipping file sizes
What is a blockage?
Apical blockage of the canal due to dentin chips, tissue debris of calcification of the canal
What are perforations?
communication between canal walls and periodontal space
How does transportation of apical foramen occurs?
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
Write the endodontic treatment up to obturation
- 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
What are the consistuents of gutta percha?
20% GP
65% zinc oxide
10% radiopacifiers
5% plasticisers
What are the disadvantages of cold lateral compaction?
voids
incomplete fusion of GP cones
lack of surface adaptation
What are the disadvantages in using sized matched cones for endo obturation?
- it leaves very little space for accessory cones
What are the three thermal techniques used in obturation?
- warm vertical compaction
- continuous wave obturation
- carrier based obturation
What are the function of RCT sealers
Seal the space between dentinal wall and core
Fills voids and irregularities in canal
lubricates during obturation
What are the ideal properties of canal sealers?
good adhesion
easily mixed
slow set
no shrinkage on setting
non staining
What materials are used in sealers?
Zinc oxide eugenol based
GI
Resin sealers (epoxy)
Calcium silicate sealers
What are the advantages and disadvantages of zinc oxide?
- Advantages : antimicrobial and cytoprotection
- Disadvantages : soluble with time and irritant
What are the properties of glass ionomer as a sealer material?
- Dentine bonding properties
- minimal antimicrobial activity and greater solubility
What are the properties of calcium silicate sealers?
- does not shrink on setting
- non resorbable
- quick set (may require moisture)
- easy to use
What are the properties of resin sealers?
- good sealing ability
- good flow
- toxicity declines after 24h
- good penetration into tubules
- biocompatible
What to check in post op radiograph (RCT)
- length
- taper
- density
- GP removal at canal orifices and to facial CEJ
- any obturation errors
What to use to close canal orifices?
RMGI
flowable composite
Zinc oxide eugenol
What are the benefits of copper enriched amalgam?
- high early strength
- high corrosion resistance
- high durability of margins
- less creep
What is the function of zinc in amalgam?
- 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.
How is copper enriched amalgam made?
By mixing silver copper eutectic particles with silver tin lathe cut particles to produce high copper y-2 free amalgam
Explain the process of delayed expansion in amalgam?
- 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
What is creep?
Creep is the slow
stressing and deformation of amalgam due to continuous low stress levels over a long period of time
What are the symptoms of amalgam creep?
- ditching of margins > microleakage > secondary caries
- Microleakage can cause pulpal irritation, secondary caries and discooration under the restoration
What areas in the upper and lower that give support in upper and lower complete dentures?
Upper = hard palate, maxillary tuberosity and residual ridge (secondary)
Lower = Retromolar pad, buccal shelf and residual ridge (secondary)
What provides support in partial dentures?
Rests (occlusal and cingulum)
What is kennedy classification?
anatomical classification that describes the number and distribution of edentulous areas present
What is kennedy class 1
bilateral free end saddle
What is Kennedy classification 2?
Unilateral free end saddle
What is kennedy classification 3
bounded saddle
What is kennedy class 4 ?
anterior bounded saddle crossing the midline
What does the palatal extension provide?
It provides increased mucosal support as a larger surface area is covered which can create a greater seal
Why do we place rest seats on anterior teeth?
it can provides indirect retention and bracing
why do we place rest seats on posterior teeth?
To offer support to the RPD preventing it from moving towards the mucosa , it can also aid in indirect retention and reciprocation
What is bracing in partial dentures?
Provides horizontal stabilization against lateral forces, ensuring the denture does not shift sideways during function.
How can bracing be achieved?
- minor connectors
- major connectors
- bracing arms
What are the different types of clasps for pre-molars?
- gingivally approaching I bar clasp
- modified t clasp
- circumferential clasp
What are the different types of clasps for molars?
Occlusally approaching single are clasp
Occlusally approaching circumferential clasp
Occlusally approaching ring clasp
Why is it beneficial to keep the gingival margin clear by not extending a partial denture framework to the anteriors?
- less mucosal coverage
- easier to clean gingival tissues
- less irritation
- better compliance
What impression materials are used for primary impressions in complete dentures?
- impression compound - non elastic
- alginate - elastic irreversible hydrocholloid
What are the consistuents of alginate?
- calcium sulphate
- Sodium alginate
- sodium phosphate
- trisodium phosphate
- flavouring
- filler particles
- salt and algenic acid
What are the consistuents of green stick?
- rosin
- carnauba wax
- talc
- stearic acid
Why place impression compound on a tooth?
- to record a single tooth crown preparation
What technique is used to record a single crown prep?
copper ring technique using impression compound
What is the procedure of the copper ring technique?
- 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
What are the advantages of the copper ring technique?
- simple
- capture details accurately
How to manage GP that is exposed for more than 3 months?
- it requires re-root treatment as it is at risk of bacterial invasion
What are the restorative options for a fractured 26 MOD amalgam which has been root treated?
- Onlay or inlay depends on the size of restoration and cuspal coverage
- Crown (MCC)
- place another amalgam restoration
What is Nayyar core?
- amalgam acting as a core extending 3-4mm into the root by removing the GP
What are the features of the nayyar core?
- 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
What two restorative materials that can bond to amalgam?
RMGIC and GI
Which bond strength is stronger amalgam or composite?
composite
What special investigation should you do and why for a patient that attends with a space between 13 and 14 ?
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
Other than aesthetics why would restoring this space be challenging?
- 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
What problems are associated with implant placement in the case of space between 13 and 14? (small space)
- 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
What are the different types of pathological tooth wear?
- 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
What are the BEWE scores ?
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
how to calculate BEWE scores
Score each sextant then add it up to assess risk
2> none
3-8 low
9-13 medium
>14 high
Name three ways teeth can be desensitised?
- Sensitivity toothpaste
- Prime and bond to protect surfaces
- Fluoride varnish
What is the DAHL technique?
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.
List 4 contraindicated groups for using DAHL technique?
- patients with active periodontal disease
- patients with TMJ problems
- patients who are on bisphosphonates
- post orthodontic treatment
- if dental implants exist
What are the consistuents of composite and give examples for each?
- Resin - Bis-GMA
- Glass - Silica or quartz
- Low weight dimethacrylate -TEGDMA
- light activator - camphorquinone
- Silane coupling agent - bifunctional molecule binding resin and filler
On a cervical abrasion cavity why would use RMGI instead of composite?
- 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
What is an RPI?
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
What are the components of the RPI system?
- Occlusal mesial rest
- Distal proximal plate (with 2-3mm undercut to guide movement)
- gingivally approaching I-bar clasp (at greatest prominence of the tooth)
What is the mechanism of action of RPI system?
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.
How would you identify a vertical bony defect?
PA radiographs
6 point pocket chart
Explain how vertical bony defects occur?
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.
How is vertical bony defects classified?
Using Goldman HM and Cohen (number of walls)
1 wall defect
2 wall defect - heals better
3 wall defect - heals better
What are the treatment options for vertical bony defects?
- 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
How do you determine the success rate of hygiene phase therapy?
- 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
If a patient is deemed suitable for periodontal regenerative surgery. What are the indications for this?
2 and 3 wall defects
Grade 2 furcation in mandibular teeth
Grade 2 buccal furcation in maxillary molars
If regenerative surgery fails for vertical bony defects , what are the alternative treatment options?
- Root resection
- XLA
- Palliative care
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?
- Size of exposure
- Time of exposure
- Vitality of the tooth
- Remaining tooth tissue
What luting cement is used for MCC adhesive bridges?
RMGI luting cement (Relyx) - HEMA monomer
Dual-cure resin cement (panavia) - 10-MDP monomer
What makes RMGIC better than GIC? and why can it be used for enamel-dentine fractures instead of GI?
- prevents micro leakage more than GI
- Seals the cavity better
- Higher compressive strength
- Higher tensile strength
- Higher bond strength
- less solubility than GIC
Why GIC is not used as a conventional restorative material?
low mechanical properties:
* low toughness
* low fracture strength
* low wear resistance
Not good aesthetics
High solubility
lower bond strength
Why is RMGIC not good as a luting cement?
- contains HEMA which causes it to swell when contaminated with moisture
- Cytotoxic to the pulp
What are the ideal properties of a luting cement?
- thickness below 25 microns
- radiopaque
- Cariostatic
- low solubility
- high compressive strength
- biocompatible
- easy to use with good viscosity
What luting cement is used for fibre post?
dual cure composite luting cement
What are the components of temp bond?
- Base : zinc oxide, starch and mineral oil
- Accelerator - EBA, eugenol and carnauba wax
Can you bond zirconia?and why?
No because it cannot be etched.
*However it has micro-mechanical retention and self etching composite with relyx bonds well to sandblasted zirconia
Are lithium disilicate crowns strong? and how ?
Yes, they have good flexural strength as crack propagation through the material is difficult
What is a good use of lithium disilicate crowns?
- can be good in adhesive bridges as they create a strong bond with resin cements
- in anterior teeth
How do you bond to non precious metals?
By sandblasting them with aluminium oxide: using10 MDP (panavia) or 4META
What type of bridge is used to replace missing laterals?
Mesial cantilever resin bonded bridge (first choice)
Fixed-fixed bridge
What abutment teeth can be used for a resin adhesive bridge to replace a lateral incisor?
Canine or central incisors
Why are mesial cantilever designs preferred over distal cantilevers?
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
What information is needed from a patient for technician to make a bridge ?
- bridge design
- master impression
- Bite registration
- Shade of teeth
What are alternative options for replacing lateral incisors other than bridges?
RPD
Implants
Do nothing
In a periodontal chart, what results would show teeth with poorest prognosis?
- 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
What patient factors affect prognosis of teeth in periodontal patients?
- Poor oral hygiene
- Smoking
- Medical history such as diabetes and immunosuppression, pregnancy
- Drug history
What could be causing anterior drifting and increase in overjet in an elderly patient?
Active and uncontrolled periodontal disease
What are the Local causes of periodontal disease?
- Calculus build up
- malpositioned teeth
- overhanging restorations
- partial dentures
- poor oral hygiene
What are the systemic causes of periodontal disease?
- 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)
What are the treatment options for an old patient presenting with periodontal disease?(mobility and drifting with increased overjet)
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
What are the causes of denture stomatitis and loose dentures? (8)
- 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
What microbes are involved in denture stomatitis?
Candida species : candida albicans and candida tropicalis
Staphylococcus species - staphylococcus aureus and staphylococcus epidermis
What is the initial treatment plan for denture stomatitis?
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
Give two topical agents that can be used for the treatment of denture stomatitis?
- Miconazole oromucosal gel 20mg/g
- Nyastatin oral suspension 100,000 units/ml
What would you see on the occlusal surfaces of a patient who have denture stomatitis and uses an inhaler?
- 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
What to do to improve denture stomatitis in the short term until it is healed?
prescribe a tissue conditioner
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)
- OVD may have changed
- Path of insertion may have changed
- Different flange extension
- Different palatal extension
- different tooth shade and shape
What are the relief areas in a complete denture?
- incisive papilla
- mid-palatine torus
What method can be used to make a denture that a patient could tolerate when replacing an old denture?
Replica dentures
What methods can dentists use to improve the fit of loose dentures?
- Reline - soft or hard lining material
- Rebase
- Remake denture
Identify features on the hard palate that may cause problems with dentures?
- high arched palate
- tori on the palate
What things should be checked at the try in stage?
- Extensions
- Retention and stability
- Occlusal plane
- occlusion (RVD, OVD and freeway space)
- Appearance (Position of the teeth, shade and shape)
- Speech
What is the shortened dental arch?
It is a dentition where most posterior teeth are missing but there is still satisfactory oral function without the use of RPD
What is the minimum requirement for an SDA?
3-5 occlusal units remaining
* occluding pair of premolars = 1 unit
* occluding pair of molars = 2 units
SDA gives priority to maintain which teeth?
Anteriors and premolars
How many units for 2 occluding premolars and a pair of molars?
4 units
Why is periodontal disease is a contraindication for SDA?
- 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
What is the neutral zone in complete dentures?
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
What skeletal classes are contraindicated with SDA and why?
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
What metal is used for casting adhesive bridges?
- NiCr and CoCr sandblasted with aluminium oxide (50 microns)
What metal is used in adhesive bridges retainers?
CoCr or NiCr
What cement is used for adhesive bridgework?
Panavia (10MDP) - anaerobic dual cure resin cement
What is the 10 year and 5 year survival rate for RRB?
5 year - 80.8
10 year - 80.4
What are the indications for SDA?
- 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
What are the contraindications for SDA? (5)
- periodontal disease
- TMJ problems
- poor prognosis of remaining teeth
- Severe class II or class III
- any signs of pathological toothwear
Sub alveolar fracture of 12 and 11present with enamel dentine fracture >1mm exposure and >24h , what is the immediate management of tooth 11?
- 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
A sub alveolar fracture is of poor prognosis why is that?
- 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
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?
- fixed cantilever
- spring cantilever for incisors
- fixed fixed bridge
what pulpal diagnosis would you give to a tooth that is sensitive to sweet?and why?
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
What are the nerves affected in reversible pulpitis and what is this called?
a-delta and A-beta fibres due to hydrodynamic microleakage stimulation
What design would you use for replacing tooth 12 to decrease debonding?
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.
What 4 faults can occur to cause a debond?
- Parafunctional habits
- Poor moisture control during cementation
- Unfavourable occlusion
- Trauma to face or oral cavity
- Poor oral hygiene
A patient undergone periodontal treatment presents as an emergency patient with pain on the 11 with swelling, TTP and lymphadenopathy - give 2 differential diagnosis?
- Periodontal abscess
- Periapical abscess
Give two special investigations to confirm diagnosis if suspected periodontal or periapical abscess?
- 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
State two ways that you can drain an abscess?
- incision or pocket retraction and irrigate with CHX/saline
Give initial management of a periodontal abscess
- 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
4 ways to check debonding of a bridge clinically?
- Probe around the bridge abutments and wing
- Push and check for any air bubbles
- Floss around bridge
- Check visually for. areas that have debonded
What is the best bridge option for a missing anterior tooth with adjacent teeth prepped?
- Spring cantilever as RRB cannot be used on adjacent teeth as they prepped
What factors should be checked by a dentist for placing implants?
General - smoking history, MH (bisphosphonate use)
Local - alveolar bone height and width and space available for implant (7mm between crowns)
What are the edentulous classifications for maxiilla?
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
What classifications of ridges are considered poor?
4,5,6
Define retention in partial dentures?
The resistance to vertical displacement
Test resistance by pulling denture vertically from anterior teeth
What is indirect retention in partial dentures?
- resistance to rotational displacement of the denture
How does composite bonds to dentine ?
- 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
How is porcelain treated to improve retention?
Etched with hydrofluoric acid producing a rough retentive surface , then it is treated by a silane coupling agent to produce a strong covalent bond
name 2 luting cements other than resin based that could be used to bond a crown?
- 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
What is the advantages of placing crowns in posterior teeth?
- Reinforce and strengthen tooth structure more than a direct restoration
Direct restorations may be more susceptible to fracture due to pressure configeration factors
How does a resin based luting cement bonds to porcelain?
- 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
potential causes of symptoms on a patient presenting of pain to transient stimuli under a recently replaced MOD composite restoration
- 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
What 5 things you could do to avoid pain after replacing an MOD composite restoration?
- 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
Describe the 4 intraoral signs of ANUG
- 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
What bacteria is involved in ANUG?
fusobacterium species
provotella intermedia
What 4 risk factors predispose someone to anug?
- Smoking
- Stress
- immunosuppression
- Poor oral hygiene
What is the initial management of ANUG?
- 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
What is TIPPS for oral hygiene?
- 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
Why might a post and core debond? (5)
- post or core fracture
- bruxism
- inadeqaute moisture control when cementing
- root fracture
- Caries
Reasons why fracture occurs at the junction of the post and core?
- Parafunctional habits (bruxism)
- Inadeqaute ferrule
- Caries
- poor post placement
What are 3 ways of removing a post?
- mosquito forceps
- masseran kit
- eggler
- ultrasonic vibration
A 28 fit and healthy patient showing periapicals of generalised bone loss , what is your diagnosis?
generalised agressive periodontitis
What 4 signs can lead you to the diagnosis of aggressive periodontitis?
- 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
What are the clinical and lab investigations for aggressive periodontitis?
- Thorough history taking
- BPE, MBPS, 6PPC
- cervicular fluid swab for microbiological analysis
How to decide prognosis of individual teeth in periodontitis?
- Loss of attachment
- Mobility
- Furcation involvement
What is the treatment plan for aggressive periodontitis?
- Perform Step 1 according to BSP guidelines
- Refer to specialist
- prescribe CHX
What is the justification behind using a lingual bar connector ?
- 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)
What features on an RPD might provide indirect retention?
- RPI systems
- Rest seats
- Major connector
- guiding planes
Why would mechanical root surface debridement not be successful in eliminating pocket bacteria? (5)
- 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
When to use antibiotics?
- when there is systemic involvement or pt is immunocompromised
How to manage a periodontal abscess that have systemic involvement?
- 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
What is a periodontal abscess?
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
What 3 criteria must be fulfilled before obturation?
- Tooth must be asymptomatic
- Canal should be fully dried
- Full biomechanical cleaning on all canals
Name the consistuents of GP
GP
zinc oxide 65%
radio-pacifiers 10%
plasticisers 5%
ZnO can alleviate pain and is bacteriostatic + a good seal
What is the function of canal sealers when used with GP cones? (3)
- seal space between dentinal walls and core
- fill voids and irregularities in canal and between GP cones
- Lubrication during obturation
What types of sealers are used for obturation? (5)
- CaOH (Dycal)
- Epoxy resin filler (AH26 plus)
- Bioceramic sealer (calcium silicate and calcium phosphate)
- RMGI
- ZOE
How do you assess obturation on a radiograph? (4)
- 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
Why do we need to obturate? (3)
- seal remaining bacteria
- prevent reinfection
- provide apical and coronal seal
Give 4 methods of obturation? (CCCW)
- cold lateral compaction
- warm vertical compaction
- continuous wave compaction
- carrier based obturation (thermafil)
What 2 temporary restorations can be provided for a patient with a fractured crown core on tooth 11 during endo?
- RMGIC
- provisional post crown
- Vacuum stent with tooth (if tooth is present)
Post materials
Metals - SS, type IV gold
Ceramics - aluminia and zirconia
Fibre - Carbon and glass fibre
Core materials
- composite
- amalgam
- glass ionomer
What factors can determine post length?
- root length and morphology
- type of post used
- crown length
- remaining tooth structure
What are the ideal dimensions for post placement?
- 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
What materials can be used to cement post and core?
- GI luting cement
- composite resin luting cement
Explain the main features in mastication and ingesion?
- ingestion > movement of food into mouth
- stage 1 oral transport > movement of food from front to back of mouth
- 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
- 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
- swallowing : bolus moves from pharynx to esophagus
What muscles are involved in ingestion?
buccinator and orbicularis oris
What anatomical structures are involved in stage 1 oral transport?
- tongue
- retraction of hyoid bone
- narrowing of the oropharynx
What muscles are involved in swallowing?
- upper esophageal sphincter
- epiglottis (preventing backflow)
- peristalis moves food to stomach
What factors improve masticatory performance?
- Sufficient oral saliva
- Sufficient dentition
3 aspects of oral function regarded by proponents of the shortened dental arch as acceptable?
- sufficient occlusal and mandibular stability
- Occlusal attrition
- Satisfactory oral function
What is occlusal stability?
Stability of tooth position in relation to its spatial relationship in the occluding dental arches
What is occlusal stability ?
It is the stability of tooth position relative to its spatial relationship in the occluding arches
What are the factors contributing to occlusal stability? (4)
Absence of pathology
periodontal support
occlusal contacts
mandibular stability
What are the requirements for occlusal stability?
- 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
Types of interventions for inadequate bone levels ?
- guided tissue regeneration
- bone grafting
- biological mediators such as emdogain (enamel matrix deriviative)
How to find the aetiology of discolouration of a discoloured tooth that sustained trauma long time ago ?
- History
- Sensibility testing
- Radiographic assessment (PA)
- Compare with clinical photographs
- Type of discolouration
What are the treatment options for a discoloured tooth?
- enamel microabrasion (HCL and pumice)
- Veneer
- bleaching (vital or non vital)
- localised composite restoration
- Accept and monitor
Describe the appearance of a vertical bony defect?
- V shaped and sharply outlined adjacent to tooth
What happens to an upper arch with complete dentures and lower anterior teeth present if the lower is not provided with a partial denture?
- 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
How is combination syndrome managed impression taking wise?
- 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
What are the 4 stages of caries removal?
- 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
When a cavity is unretentive for Amalgam , what 4 alternative techniques or materials can you use?
- 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
What would you look for if you place a restoration on a non root treated tooth at review?
- Sensibility testing to check pulpal response
- Radiographic changes
How does the clinical presentation of caries compares to a radiograph?
- 2-3mm deeper clinically than shown on radiograph
Describe the procedure of Cveck pulpotomy
- 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
What is the procedure in a normal pulpotomy?
- 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
Name 4 different types of composite?
microfilled
nanofilled
hybrid
flowable
What are the clinical disadvantages of composite and how are they minimised?
- 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
What are the advantages of composite over amalgam? (4)
- extended working time - on demand set
- minimal preparation - tooth tissue preserved
- Better aesthetics - range of shades
- Bonds chemically to tooth
What is the response of
Healthy periodontium
Reduced periodontium
Pathological periodontium
to traumatic occlusion?
- 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
How do you manage a traumatic occlusion in patients with periodontitis?
- 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
What factors influence localised mobility? (5)
- Periodontal disease
- Traumatic occlusion leading to widening of the PDL
- Alveolar bone loss
- trauma
- Smoking
When might splinting be advised in periodontal treatment?
- 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
Why is there a decrease in mobility after periodontal treatment?
- due to increased tissue tone and regain of junctional epithelium attachment
What can you do if the PDL is widened after successful periodontal treatment? in a patient with traumatic occlusion
- Reduce high contacts that are causing traumatic occlusion
What is fremitus?
- 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
- 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
- Chronic periodontal disease
- Traumatic lesion from denture
- Lichenoid tissue reaction to amalgam
- Lichen planus
- Oral cancer??
Based on the previous question
- What special investigations would you take
- 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
Based on the previous question
What are the treatment options?
- 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
- 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
- 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
- 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)
- 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
- 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?
Paget’s disease causing hypercementosis
other dental changes of paget’s disease include : loss of lamina dura and tooth migration due to bone enlargement
- 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?
- 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
What precautions would you take when extracting a tooth for a patient with bisphosphonates? (8)
- 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
What is paget’s disease?
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
Incidence of paget’s disease
affect males more and patients over the age of 40
What are types of paget’s disease?
- osteoporotic
- osteosclerotic
- mixed
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)?
- 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
What are the signs and symptoms of extrusion of sodium hypochlorite from the root apex? (4)
- acute inflammatory reaction
- oedema
- bleeding
- tissue necrosis
What is the immediate management of sodium hypochlorite extrusion? (4)
- 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
What is your management of a sodium hypochlorite incident after performing the immediate management? (5)
- 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
How to prevent sodium hypochlorite extrusion? (6)
- 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
- 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 ?
- using the parallax technique
- using an OPT and a PA / occlusal radiograph
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)
- Risk of MRONJ due to bisphosphonate use
- bleeding
- swelling
- bruising
- infection
- dry socket
- nerve damage at the area of the mental nerve
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)
- 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
Pt asks about the alternatives of amalgam, usually what are patients concerns about amalgam? (6)
- aesthetics
- mercury poisoning and toxicity
- environmental impact
- tooth discolourations and surrounding tissues
- affect foetal development during pregnancy
- metal allergies
How to reassure a patient about the safety of amalgam? (4)
- 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
The EU advices to not use amalgam on which groups of patient and why? (3)
- breastfeeding women
- Pregnant women
- children under the age of 15
This is due to phasing down the use of amalgam
What aspects of the cavity preparation of amalgam ensure caries are removed?
- 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
What aspects of cavity preparation ensure that the restoration will be adequately cleans-able ?
- No unsupported enamel (overhangs)
- Removal of contact points
- Smooth margins
- Smooth occlusal surface
Describe how dentine bonds to composite?
- 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
How long is enamel acid etched and what is the bond created with acid etched enamel and composite?
- 20 seconds
- micro-mechanical retention
What is the distribution of local anaesthesias?
Block and infiltration
- Block : deposited beside the nerve trunk
- infiltration : deposited around the terminal branches of the nerves
What is the mechanism of action of local anaesthesias in pain control? (3)
- 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
What nerve fibre’s are most susceptible to LA? and why
- 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
What are the consistuents of LA?
- Aromatic region - hydrophobic
- Ester/amide bond - anaesthetics part
- Basic amine side chain - hydrophilic
Name ester anaesthetics? (2)
- benzocaine
- procaine
Name amide anaesthetics? (4)
- lignocaine
- prilocaine
- articaine
- bupivicaine
What is the maximum dose of lignocaine?
- 2% lignocaine HCL + 1:80,000 adrenaline
- max dose is 4.4mg/kg
What is the max dose of articaine?
- 4% articaine 1:100,000 adrenalin
- 7mg/kg
Give 6 methods for removing fractured posts
- ultrasonic vibration
- use of masserann kit
- eggler post removal
- sliding hammer
- cut out for fibre post
What are the temporary/immediate options for replacing a fractured tooth crown from the roots? (4)
- provisional over denture
- provisional post crown
- vacuum formed splint with replacement tooth
- adhesive cantilever bridge with fractured crown as pontic (use composite)
What may be used to cement a post? (5)
- 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
What are the clinical signs of erosion? (6)
- 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
What occlusal records you need to check in toothwear?
- 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
What are the causative factors of erosion? (4)
- 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
How is erosion managed? (4)
- 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
How to manage reversible pulpitis?
- remove causative agents such as
Caries
Deep restorations - place liner
Use desensitising agents - follow up to check if inflammation resolved and symptoms cleared out
What are the typical signs of reversible pulpitis?
- 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
What is symptomatic irreversible pulpitis?
- 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
List the signs and symptoms of irreversible symptomatic pulpitis? (7)
- 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
What are the causative factors of irreversible pulpitis? (3)
- deep caries into pulp
- extensive restorations
- fractures exposing pulpal tissues
What are the characteristics of an ideal post?
- 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
How to increase bond strength of a non threaded post?
- Sand blast to increase surface area
What is the difference between threaded and non threaded posts in terms of stress to tooth?
- threaded causes more stress to the tooth structure unlike non threaded which are passive
How can a post be assessed for suitability
- 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)
How does the tooth type can affect the indications of posts?
- 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
Why should posts be avoided in curved canals? (1)
- to avoid perforations
What should be a post width?
- no more than 1/3 root width at narrowest point
- 1mm of circumferential coronal dentine is required
What are the ideal dimensions of a ferrule for placing a post?
at least 1.5mm width and height of circumferential dentine
Give 3 core materials
Composite
Amalgam
GIC
What to check in outline form modification during cavity preparation? (3)
- Enamel finishing
- Occlusion
- suitable restorative material
What to check in internal cavity preparation?
- internal line and point angle
- cavosurface angle
- requirements of the restorative material
What are the different types of dentine and how to do they affect binding?
*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
What is the inorganic content percentage in dentine?
- 70% calcium hydroxyapatite
What is the setting reaction for normal and copper enriched amalgam?
normal = y + hg -> y + y1 + y2
Copped enriched = y2 + AgCu = Cu6Sn5 + y1
What changes have been made to modern amalgam to improve it ?
- has high copper content by adding silver copper particles to silver tin lathe cut particles
What is the function of copper in copper enriched amalgam?
chemically
- it reacts with tin to reduce the availability of tin for y2 phase
Why is zinc not used in modern day amalgam?
because it reacts with water and form slag causing a poor marginal seal
What are the advantages of amalgam?
- longer lasting
- cheaper
- easy to handle and less finishing
- have high hardness, compressive strength and abrasion resistance
Why y2 amalgam is not as good as copper enriched amalgam?
- low abrasion resistance
- poor strength
What are the disadvantages of amalgam (4)
- 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
What percentage of maxillary first molars have a second mesiobuccal canal?
- 93% have 4 canals
- 7% have 3 canals
What are the 3 design objectives in endodontics?
- Create a continuously tapering funnel shape
- Keep apical foramen in original position
- Keep apical constriction as small as possible
Access cavities for endodontic treatment
What are the advantages of the crown down technique?
- 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
What is the irrigation protocol after shaping the canal ?
EDTA 17% for 1 minute
NaCL 3% for 10 minutes 30ml
slow injection using index finger
What is gradual curvature? and abrupt curvature of the canal?
- 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
Name 3 laws of pulpal floor anatomy?
- 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)
Give 3 rules for locating orifices in the pulpal floor
- always at the junction of the floor and wall
- always at angle of floor and wall junction
- always at terminus of developmental fusion lines
Give 4 reasons for irrigation during endodontic treatment?
- disinfect the root canals
- dissolve organic debris and flush out debris
- to lubricate root canal systems
- remove endodontic smear layer
Why is sodium hypochlorite a good irrigant?
- high antimicrobial activity
- dissolves organic pulp necrotic tissue
- disrupt the smear layer
- dissolves pulp remnants and collagen
What strength of NaoCl is used in the root canal system?
3%
Name another irrigant used in endodontics other naocl?
Chlorhexidine digluconate
EDTA
How is the smear layer removed ?
- 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
Name 2 intracanal medicaments and state their use
- Antimicrobial paste (ledermix) :
reduce pulpal inflammation - non setting calcium hydroxide:
antibacterial effect
reduce inflammation
reduce bacterial load
removes tissue debris
What are the indications of a resin retained bridge?(5)
- 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
What are the contraindications for a resin retained bridge? (6)
- 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
Which cement for a porcelain bridge? (fixed)
Nexus (dual cure resin cement)
Which cement for an adhesive resin retained bridge?
Panavia 21 (10-MDP)
what to cement an all metal bridge ?
- Aquacem (GIC)
- relyx (RMCIC)
When is a dual cure cement indicated?
- when cementing a thick indirect restoration that light cannot penetrate it
Where is silane coupling agent used?
- bonds resin to filler in composite resin
- bonds etched porcelain to resin cements
Describe chemically how silane coupling agent work
- 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
Describe the appearance of attrittion? (4)
- lesions on occlual and incisal surfaces
- flattening of incisal edges
- reduction of cusp height and flattening of inclined teeth planes
- Wear on restorations
Describe the appearance of abrasion (4)
- 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
Describe the appearance of abfraction
- wear at cervical margin shows as V shaped due to eccentric occlusal forces leading to compressive and tensile stress on the cervical margins
How may toothwear be monitored? (3)
- using BEWE or night a smith index
- using study models
- using clinical photographs
What percentage of adults have toothwear?
77% have some form of tooth wear anteriorly involving dentine
Give 4 intrinsic and extrinsic causes of tooth discolouration?
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
How does vital bleaching with hydrogen peroxide works? (3)
- 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
What is the common active ingredient in tooth whitening bleach and how is it related to hydrogen peroxide (at home)?
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
Give 4 risks of vital bleaching
- Gingival irritation
- Tooth sensitivity
- Effect can wear off
- spillage of bleaching agents
What is the procedure of vital bleaching?(home bleaching)
- 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
Why is it not advised to use bleaching agents on people under the age of 18?
- May cause increased sensitivity due to higher permeability of dentine and enamel
What are the key features of a cavity for composite? (3)
- no unsupported enamel
- no sharp internal line angles
- Bevel cavo-surface margins to increase bonding
Give 3 reasons for instrumenting the root canal system (4)
- remove infected soft and hard tissue
- create reservoir for irrigants in canal space
- create space for medicaments and obturation
- retain integrity of radicular structures
What is the Protaper sequence
- 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
What advantages do pro-taper (NiTi) files have over K files? (6)
- 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
Name other rotary systems other than protaper?
- reciproc
- Protaper gold
Name and describe 2 other motions for files other than reaming and filing?
- watch winding : back and forth movement (30-60 degrees)
- balanced force : 1/4 CW turn then CCW 1/2 turn
Name 3 reasons a file may separate? (3)
- flexural stress (repeated cyclic fatigue)
- Torsional stress (binding to canal wall)
- Complicated curved canal (non straight line access)
Describe reaming and filing
- reaming - clockwise motion and apical pressure
- Filing - push and pull motion
Advantages of K files (4)
- cost effective
- good canal exploration
- achieve apical patency
- determines curvature
Draw and label posselt’s envelope
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
Describe the path of RCP-ICP
- 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
What is Hanau’s quint?
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
What is the thickness of shim-stock and articulating paper?
Articulating paper > 20 um with miller forceps
Shim stock > 8um with mosquito forceps
What is the average biological width?
2mm (connective tissue 1mm ; junctional epithelium 1mm)
the combined height of the connective tissue attachment and the epithelial attachment above the alveolar bone
How can amalgam overhangs be avoided? (3)
- adequate condensation of amalgam
- using wedges between teeth
- correct matrix adaptation
What problems may occur due to overhangs? (2)
- 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)
How do you manage overhangs? (2)
- Replace restoration
- Repair using high speed or soflex discs
Give 4 functions of a facebow?
- 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
Why anterior guidance is preferred to posterior guidance? (4)
- 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
What are the ideal properties of a denture base? (7)
- 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
What are the consistuents of PMMA
- powder
benzoyl peroxide (initiator)
PMMA particles
Plasticisers
Co-polymer - Liquid
methacrylate monomer (polymerises)
Co-polymer
hydroquinone (inhibitor)
Remeber the powder as 4P’s
Give 4 possible faults while manufacturing acrylic and why does it occur?
- 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
What are the principles of tooth preparation for crowns (6)
- 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
How to decide on tooth crown preparation in tooth structure conservation?
balance between resistance , retention and structural durability
What happens when under preparing a tooth for a crown? (3)
- poor aesthetics
- occlusion consequences
- periodontal consequences
What happens when overpreparing a tooth for a crown? (2)
- pulp damage
- tooth strength compromised
How to achieve retention in crown prep? (2)
- limiting the number of paths of insertion
- grooves and slots
What is the ideal inclination of crown walls?
6 degrees
Why is length of walls important in crown preparation?
prevents tipping displacement (longer walls are better)
When is the path of insertion of crown prep determined?
before preparation begins
How is structural durability achieved in crown prep? (3)
- occlusal reduction
- axial reduction
- functional cusp bevel
How to achieve marginal integrity in crown prep?
By preparing finish line configurations to reduce microleakage such as chamfer or shoulder
What are the types of finish line configurations in crown prep (5)
- knife edge
- bevel
- chamfer
- shoulder
- beveled shoulder
How should margins of the crown preparation be to preserve the periodontium? (3)
- 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
What are the stages of crown preparation? (6)
- 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
What considerations during occlusal reduction of a crown?
- retain some occlusal morphology
- consider thickness of metal and porcelain
- check occlusal clearance
What degree of taper is ideal in separation? (crown prep)
5-10
In how many planes should you prepare buccal aspect in crown prep?
2 planes (apical and coronal)
palatal/lingual is completed in one plane - follow palatal contour for anteriors and canines
What structure should you avoid when preparing a crown prep (buccal)
pulp horns
What is the most common reason lab cannot construct crown?
insufficient occlusal clearance
Reduction dimesions for crowns
Give advantages of CoCr metal base? (5)
- 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
What are the ideal properties of impression materials? (6)
- 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
Name 4 non -elastic impression materials
- impression compound
- zinc oxide eugenol
- impression wax
- impression plaster
Name 4 elastomer impression materials?
- Polysulphides
- Polyether - Impregum
- Addition curing silicone - aquasil ultra
- Condensation curing silicone - Verone
Name 2 hydrocholloid impression materials
- agar - reversible
- alginate - irreversible
What is the setting reaction for alginate?
Sodium alginate -> Calcium alginate
Give 2 advantages of alginate
- 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)
Give 2 disadvantages of alginate?
- poor tear strength
- limited dimensional stability - should be placed in moisture as it is susceptible to dehydration and shrinkage
- Single use
Give uses of alginate (3)
- Primary impressions for complete/RPD
- Impression for indirect restoration
- wound and burn dressing
Give advantages of other elastomeric impressions over alginate? (6)
- 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
What is the composition of GI?
Acid - polyacrylic acid and tartaric acid
**Base **
Quartz
Aluminia
Aluminium phosphate
Aluminium flouride
Calcium fluoride
Sodium fluoride
Describe the setting reaction of GI
- 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
Give 5 uses of glass ionomer
- core build up for crown
- indirect restoration cementation
- cervical restorations due to poor moisture control
- temporary restoration
- fissure sealant for uncooperative children
Give 6 properties of glass ionomer?
- 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
Give 4 disadvantages of GI?
- brittle with poor wear resistance
- moisture susceptible when first placed
- poor aesthetics
- poor handling characteristics
What is a knife edge ridge?
It is a class of alveolar ridge that is resorbed laterally (labial/buccal - palatal/lingual)
Name three causes of a knife edge ridge?
- periodontal disease before extractions
- traumatic surgical extraction
- immediate dentures
How can knife edge ridge be managed for complete dentures? (4)
- 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
What is the difference between soft lining and tissue conditioner?
- 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
What is a functional impression?
- 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
Define retention and stability of a denture?
- retention - the resistance to vertical displacement
- stability - resistance to lateral displacement
How is an upper complete denture retained? (4)
- Muscles
- Extension to buccal sulcus and peripheral seal
- Adhesion and cohesion
- Post dam position
Other than remaking how can you improve retention of a dentures? (4)
- relining
- rebasing
- implant retained
- precision attachements
What are the indications of replica dentures? (3)
- Pt satisfied with current denture but need some improvements
- replacement of successful immediate denture
- Worn denture
How to restore freeway space in a very worn denture? (2)
- use occlusal pivots to stabilise occlusion then make new dentures
- Restore occlusal surface with self curing acrylic resin
Describe the process of making a replica denture (9)
- 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
Denture anatomy
What problems can an incorrect OVD cause?
- TMJ problems
- clicking on teeth when eating
- Angular cheilitis
- Occlusal trauma
- pain in mandibular muscles
Where is the post dam?
- 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
Where is the post dam located in regards to the palatine fovae?
1-2mm anteriorly
where is the distal extension of a lower complete denture?
2/3 into the retromolar pads
Why is the buccal shelf used for support?
- because it is a non resorbable region which can provide adequate support
What anatomical features help set the incisors?
- facial symmetry and philitrum for midline
- incisive papilla (1cm anterior to it
- Lip line - 1-2mm of incisal edge show at rest
- frenulum?
What 4 things make up the shade of teeth?
- chroma - saturation of the color
- Hue - color
- translucency - how much light pass through
- value - how much light reflects
3 ways to measure OVD
- dividers
- ruler
- willis bite gauge
Give the average horizontal bone loss for
incisors
canines
premolars
molars
incisors - 6mm
canines - 8mm
premolars - 10mm
molars - 12mm
What is the difference between horizontal and angular bone loss?
- 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
How is angular periodontitis caused?
- 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
Define generalised and localised bone loss?
Generalised - affecting more than 30% of sites
Localised - affecting less than 30% of sites
Define mild moderate and severe bone loss
- mild is more than 30%
- moderate is 30-50%
- Severe is more than 50%
What are the advantages of immediate dentures? (4)
- 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)
What are the disadvantages of an immediate denture? (4)
- 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
Write a prescription for upper/lower complete denture special tray
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
What is the difference between generalised and localised aggressive periodontitis?
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
What is the new periodontal classification (2018)
AAP CLASSIFICATION 2018
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
What bacteria is usually involved in periodontitis?
- P.gingivalis
- A. actinomycetemcomtians
What things are recorded in a periodontal pocket chart ? (8)
- furcation involvement
- tooth mobility
- plaque index
- bleeding on probing
- loss of attachment
- missing teeth
- pocket depth
- degree of gingival recession
How is mobility graded?
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)
How is furcation graded?
1 - less than 3mm horizontal
2 - more than 3mm but not through through
3 - through through
How is gingival recession graded ?
Using miller classification
Give 2 disadvantages of a pocket chart
- 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
What are the local causes of gingival recession? (9)
- smoking
- high frenal attachments
- Poor marginal restorations
- Fixed orthodontic appliances
- Abrasive toothpaste
- parafunctional habits
- Periodontitis
- Trauma by tooth brushing
- crowding
- traumatic overbite
Special investigations to measure recession?
- 6PPC
- Study models
- Clinical photographs
How is localised recession managed?
- 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
What types of surgeries are used to manage gingival recession
- Free soft tissue graft from palate
- coronal advancement flap in severe cases
- tunnel preparation technique
What are the modified systemic factors that can cause periodontitis? (7)
- smoking
- stress
- hormones - pregnancy, puberty
- Drugs
- Diabetes
- cardiovascular disease
- Obesity - due to poor diet and lifestyle
What drugs might cause gingival hyperplasia?
- Phenytoin : anti-epileptic
- Amlodipine : Ca channel blocker
- Cyclosporine : immunosuppressant
Gingival hyperplasia may cause periodontitis
What are the defect systemic factors that may cause periodontitis?
- monogenetic syndromes such as
Sickle cell anaemia
Cystic fibrosis
Polycysytic kidney disease - Down’s syndrome
Why is diabetes a risk factor for periodontal disease? (4)
- It causes impaired wound healing
- heightened inflammatory response
- Alters collagen production (decreased)
- Causes microangiopathy
- xerostomia and increased sugar in saliva leading to increased plaque
Describe how diabetes affect the periodontium biologically?
- 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
What tests are carried out for diabetes and diabetic control? (4)
- fasting glucose test
- blood glucose home testing kits
- HbA1c
- glucose tolerance test
What is the ideal value for HbA1c test in diabetic patients and how often is it carried out?
48 mmol/mol (6.5%) or below every 3-6 months
How does smoking affect the periodontal tissues? (7)
- staining
- xerostomia
- gingival recession
- increases disease anteriorly
- reduced bleeding on probing
- halitosis
- hyperkeratosis
What is interleukin-1?
- It is a highly pro-inflammatory cytokine produced by immune cells
- It regulates the immune response
What are the aims of periodontal step 1 ?
- 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
What is the overall aim of periodontal therapy?
- 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
How is step 1 provided?
- 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
Name the causes of gingival hyperplasia?
- Systemic disease - granulomatous disease, Leukaemia, fibroma, giant cell granuloma
- Drug induced - phenytoin, amlodipine, cyclosporine
- conditioned enlargement due to pregnancy or puberty, vitamin C deficiency
What is the classic pattern of gingival hyperplasia?
*Starts at the interdental papilla and develop to include the entire attached mucosa
How does gingival overgrowth influence periodontal disease?
- difficult plaque control
- increase pocket depth
- increases inflammation due to the oedematous inflammatory component
no evidence of gingival overgrowth as a predisposing factor
How is gingival overgrowth managed / with periodontal disease?
- Step 1 perio
- Surgical interventions : gingivectomy, gingivoplasty
- Consult with GMP to discuss change of medication
- Regular monitoring
Examples of developmental bone pathologies?
- Tori - benign bone growth in mouth (mandibular tori)
- Fibrous dysplasia - fibrous tissue replace bone
Examples of inflammatory bone pathologies?
- Dry socket (alveolar osteitis)
- Osteomyelitis (bone infection)
Examples of neoplasm bone infection
- Osteoma (benign tumour made of bone)
- Osteosacroma (bone cancer)
- Osteoblastoma ( bone destoryed and replaced by weaker tissue )
Examples of metabolic bone pathologies?
- Osteoporosis (weakened bones)
- Paget’s disease (bone expansion and weakening)
Give 4 differential diagnosis for a multilocular radiolucency?
- Ameloblastoma
- Giant cell granuloma
- Odontogenic myxoma
- Odontogenic keratocyst
- Cherubism (abnormal bone tissue in the bone)
What is the reason for distorted anterior teeth in a radiograph?
Patient not in the focal plane (patient too forward in the machine)
What is the reason of a blurry image on radiograph?
Patient moving during exposure
What causes an image to be too wide on a radiograph?
Patient too far back in the machine (patient canine behind machine canine line)
How to limit radiographic positioning errors? (4)
- use chin rests
- use bite blocks between incisors
- use hand rests to prevent movement
- correct positioning of guide lines : canine, centreline, frankfort plane
What are the characteristics of ghost images on a radiograph?
- Higher due to vertical beam angulation (-8)
- Horizontally magnified and distorted
- opposite side
- further forward - due to change in anterior posterior position
What are the ways to reduce patient dose to radiation? (3)
- 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
What is compton scatter effect?
- 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
What compton scatter and absorption depend on ?
- proportionate to density of material
- not affected by atomic number or photon energy
What is photoelectric absorption effect in radiology?
- 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
What does photoelectric effect depends on?
- atomic number
*density of material - photon energy
What metal is used for absorption in x-rays?
lead
Why is lead used for absorption in x-rays?
- 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
Name other metals than lead that are used in x ray machine
Copper - heat conductor
Tungston - cathode filament
Aluminum - filtration
Give 5 radiation safety features? regarding IRR99
- 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
What is ALARA
- as low as reasonably achievable
This is to minimise dose and exposure and keep exposure below limits whenever possible
How is ALARA achieved?
- 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
Why is it advised to use E speed film or faster/direct digital film in radiation?
Because there will be fewer x-ray photons required = lower dose to patient
What are IRMER2000 guidelines? ( ionising radiation medical exposure regulations)
- 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)
What are the three main principles of radiation protection
- justification
- optimisation - ALARP
- Dose limitation - for radiation workers and members
What are the 4 personnel and roles in IRMER
- Employer
- Referrer
- Practitioner (IRMER practitioner)
- Operator
What is the role of the employer in IRMER?
- legal person responsible for safety
- makes sure equipment is in line with regulations
- ensure staff are trained and follow these regulations
What is the role of the referrer in IRMER?
- person requesting radiograph
- need to take history and do clinical examination prior to referral
- Justifies the exposure
What is the role of the practitioner in IRMER?
- confirms justification and authorise exposure request
- must ensure doses are ALARP
- can be dentist, radiologist or specialist
What is the role of the operator in IRMER?
- person who takes and reports the radiograph to help aid diagnosis
- notes exposure and ensure x-ray are in accordance with IRMER and ALARP
Why should you report a radiograph? (6)
- to aid diagnosis
- written record of patient dentition
- aid in treatment planning
*medico-legal reasons - ensures best practice
- audit purposes
What is paralleling technique in radiology?
- 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
What is bisecting angle technique in radiology?
- 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
How to reduce magnification when taking a radiograph with paralleling technique?
Use long x-ray fsd 20cm
What factors does an implantologist consider before placing an implant ? (7)
- 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
What bone dimensions are required for implant placement and how are they measured?
- 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 **
Name possible common complications for extracting a standing alone maxillary molar?
- OAC
- root or tooth lost in maxillary sinus
- Maxillary tuberosity fracture
Label Condyle, hard palate, zygomatic buttress, styloid process, soft palate
hyoid bone, nasal septum, ear lobe, bite peg and ghost image
Label denture bearing areas anatomy of the upper and lower arch
List 3 side effects associated directly with the chronic use of cocaine on the structures in the head and neck?
- Numbness of the gingivae
- Erosion of the floor of the nasal cavity creating OAF/OAC
- Wear due to bruxism
- Ulceration in the gingivae
List 2 complications in the dental surgery of local anaesthesia with adrenaline is administered to a patient who recently took cocaine?
- increase in heart rate - heart palpitations and loss of consciousness
- mood swings - may get aggressive
How do you cement a porcelain bridge?
- 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
How do you cement a metal bridge ?
10-MDP or 4-META
How is the surface of pocelain treated in the lab to improve adhesion?
- Etched with hydrofluoric acid
When is a dual cured cement indicated ?
- Cementing a thick or opaque indirect restoration that a light cure cannot penetrate
A patient attend with a debonded cast gold post and core , give 4 reasons for a debond?
- Incorrect cementation material
- Contamination during cementation
- Unfavoured occlusion
- Inadequate post preparation
Why might a core fracture from a post?
- Casting error
- Inadeqaute ferrule
- Trauma
- Bruxism
