Restorative - Miscellaneous/mixed, crown, bridge, post, toothwear, SDA, occlusion, implant, whitening, cavity prep Flashcards
1
Q
A 19-year-old patient attends you practice on a Monday morning having sustained trauma to teeth 12 and 11 on the Saturday evening. Tooth 12 is completely missing the crown and has a sub-alveolar fracture. Tooth 11 have a pulpal exposure of 2mm. Both teeth are experiencing sensitivity.
1. Discuss fours steps in the immediate management of tooth 11? (4)
A
- Locate the missing fragment (if patient cannot locate and querying aspiration risk then send to A&E)
- Check for soft tissue damage and radiograph if possible to assess for any other pathology
- As exposure is large and over 24hrs a direct pulp cap is not indicated must proceed to pulpotomy (and possible pulpectomy)
- Give LA, isolate tooth with rubber dam (if possible) and clean the area with saline
- Start with pulpotomy- access, remove coronal pulp to depth of 1-2mm, attempt to achieve haemostasis using cotton wool and saline
- If haemostasis achieved place CaOH in canal, seal exposed dentine with GIC and restore with composite (bandage or full restoration depending on time)
- If unable to achieve haemostasis (hyperaemic pulp- indication tooth non vital) then continue to complete pulpotomy (all coronal pulp tissue removed) and if haemostasis still unachievable proceed to full RCT (extirpation of pulp and placement of intra-canal medication until next appointment when tooth should be obturated)
2
Q
Tooth 12 has a sub-alveolar fracture with crown missing and is rendered unrestorable. Why is a sub-alveolar fracture important in making the tooth unrestorable? (4)
A
- Poor moisture control as below gingivae
- Lack of coronal tissue for bonding or support
- subgingival margins mean that it will be hard for the patient to clean the margins and impinge on the biological width which will impact the health of the gingivae
- lack of coronal seal
3
Q
Name two alternative to replace tooth 12 (unrestorable) after extraction?
A
Implant
Bridge resin retained
SIngle tooth RPD
4
Q
A patient presents with a fractured 26 MOD amalgam. The tooth is root treated. Both buccal cusps have fractured and there is exposed GP.
1. What are the restorative options for this tooth? (2)
A
- Crown MCC
- Onlay with cuspal coverage
N.B non-restorative options would include extraction and prosthetic replacement or overdenture.
5
Q
The root filling has been exposed for 6 months. What is your treatment and why? (2)
A
- Re-RCT before then restoring with new definative restoration
- GP has been exposed to the oral enviroment for more than 1-3months which is the guidance for how long GP takes to become infected.
6
Q
Give 2 features of a Nayyar core? (2)
A
- 2-4mm of GP is rmeoved from canal and replaced with amalgam
- Retention obtained from undercut in divergent canals and pulp canal chamber
7
Q
Name two restorative material in dentistry that can bond amalgam to a tooth? (2)
A
- GI
- RMGI
8
Q
How would you bond composite to a tooth? Give two dental materials and examples? (2)
A
- First prepare the tooth surface with a etch (35% phosphoric acid). This removes the smear layer, opens dentine tubules and exposes collagen network for penetration and micromechanical retention.
- Then place primer and adhesive (prime and bond). Primer usually HEMA (acts as a coupling agent with a hydrophillic end to bond to the dentine and a hydrophobic end which bonds to the resin. And adhesive usually mixture of Bis-GMA and HEMA resins (penetrates primed dentine and forms a micromechanical bond via molecular entanglement with exposed collagen to form the hydrid layer of collagen plus resin
9
Q
Which bond strength is stronger between amalgam and composite? (1)
A
Composite
10
Q
The patient has a large amalgam restoration replaced in composite due to secondary caries. Radiograph was taken a week ago at the placement of the composite and no caries or pathology are visible.
1. Give 5 causes of the transient sensitivity to thermal stimuli and biting that they are experiencing?
What are the possible causes of sensitivity
A
- Deep restoration close to the pulp with no lining material placed
- Pulpal exposure
- Tooth preparation irritates the pulp (not enough coolant)
- Inadequate curing of resin which leads to soggy material irritating the pulp
- Restoration high in occlusion
- Cracked tooth
- Debond or microleakage as a result of poor moisture control
- Debond or microleakage as a result of polymerization contraction stress
11
Q
Give 5 restorative management features that could prevent transient sensitivity to thermal stimuli and biting that they are experiencing from occurring?
A
- Placement of lining material for deep restoration to reduce irritation to pulp
- If expose pulp then pulp cap
- Ensure high speed is used with copious water irrigation and consider caries removal with excavator or slow speed for deep caries
- Cure in 2mm increments to prevent uncured material and soggy bottom from irritating the pulp
- Use articulating paper to check occlusion and reduce as required
- Ensure good moisture control with dam or cotton wool
- Place smaller increments to reduce polymerisation contraction stress or use indirect restoration
- Cracked tooth, difficult to diagnose but can use tooth sleuth, consider cuspal coverage.
12
Q
Shown a PA radiograph of impacted 38 and 37 with caries present.
1. Patient is experiencing a dull throbbing pain in the region give a differential diagnosis for what could be keeping the patient up at night?
A
- Irreversible pulpitis
- Pericornitis
- Otitis media (ear ache)
- TMJ
13
Q
A patient presents with a discoloured anterior tooth. It is not sensitive or symptomatic, but he reports he sustained a blow to it a couple years ago and the discolouration is getting worse.
1. How would you go about finding the aetiology of the discolouration?
A
- Thorough history and examination
- Pulp testing
- Compare current colour with older clinical photographs
14
Q
A patient presents with a discoloured anterior tooth. It is not sensitive or symptomatic, but he reports he sustained a blow to it a couple years ago and the discolouration is getting worse.
2. What special investigations would you undertake?
A
- Radiographs
- Pulp testing
- TTP
- Precussion note
15
Q
What treatment options are there for discolouration?
A
- Leave and monitor
- Vital or non-vital bleaching
- Composite veneer
- Porcelain veneer
- Microabrasion
16
Q
Patient presents with MCC in hand from upper central.
1. What features of a tooth will make it more likely to make it successful/unsuccessful for treatment?
A
- Presence of ferrule
- Amount of tooth tissue remaining
- Periodontal health of tooth
- Mobility of the tooth
- Caries level, does it extend sub ginigval
- Pulp status
17
Q
- Give 3 short term options to replace a MCC that has fallen out of a patients mouth (its an upper central) and explain them?
A
- Attempt to recement the crown, using a non-eugenol temporary cement. This protects the remaining tooth structure while a new crown is produced.
- Make a provisional using pro temp and temp bond
- Place adhesive cantilever bridge with wing on adjacent incisor, keep away from ginigval margin to prevent inflammation before taking impression for new crown.
18
Q
How can you check that a bridge has debonded?
A
- Visual assessment, can you see seperation
- Probe to check around the abutment pontic and wings, checking for gaps
- Mobility of the bridge
- Floss around the bridge
19
Q
What factors should be taken into consideration before placing a bridge?
A
- Health/prognosis of the surrounding teeth, especially the abutment teeth
- The periotonal status of pateint
- OH status
- How long is the edentulous span
- Is it in the aesthetic area and does the patient have a high lip line
- Dynamic occlusal relationship
- History of parafunction
20
Q
What alternative are there to a bridge?
A
- Accept the space
- Implant
- RPD
- Close space with orthodontics
- overdenture
21
Q
What are the indications for resin retained bridge?
A
- Enough healthy enamel to bond
- Large abutment tooth to bond too
- Less destructive, patient doesnt want to lose healthy tooth tissue
- Minimal occlusal load
- Single pontic tooth (small edentulous space)
- Simplify partial denture design
22
Q
What are the contra-indications, for resin retained bridges?
A
- Lack of healthy enamel remaining
- Small crown abutment
- More than a single tooth space
- Heavy occlusal forces or parafunctional habits
- Poorly aligned, tilited or spaced teeth
23
Q
How do you cement a porcelain bridge?
A
- Make sure the tooth surface is extremely dry
- ## Then use a duel cured resin cement (NEXUS)
with use of a saline coupling agent ? no dont require any bonding agent
24
Q
How do you cement a metal bridge?
A
- Panavia (dual cured adhesive resin which contains 10-MDP (a metal bonding agent)
- GI (aquacem)
- RMGI (relyX) luting cements
25
What is a luting cement?
- A dental cement that is used to attach indirect restorations to prepared teeth
- It fills any voids and mechanically locks the restoration in place to prevent any dislodgement during mastication.
26
A patient attends your practice complaining of pain from tooth 12 and a de-bonded bridge (fitted three months ago)
1. What is the likely design of the bridge? (1)
- Adhesive bridge with two retainers
27
A patient attends your practice complaining of pain from tooth 12 and a de-bonded bridge (fitted three months ago)
- What is a reasonable different diagnosis for the pain from tooth 12? (1)
- Reversible pulpitis (short sharp pain apon stimulis (hot,cold, sweet) which then disappears within a few seconds once stimuli is removed)
- No TTP
- well localised (check this)
28
The bridge deboned on abutment tooth 12 but not abutment tooth 21. The debonded wing on the 12 became a plaque trap leading to caries and ultimately causing pain. Name a better alternative bridge design for the patient and explain why your design would be better? (2)
- Adhesive cantilever bridge on the 21
- As there is now only one wing abutment if it debonds the bridge will come off and there will be no plaque trap and no caries
- Being less destructive as only etching the surface of one tooth
29
Name 4 factors that could cause a bridge to de-bond? (4)
- Poor moisture control when placing the bridge
- High occlusal forces
- Parafunction habits
- Trauma
- Poor OH
- Unsuitable abutment teeth
30
The bridge deboned on abutment tooth 12 but not abutment tooth 21. The debonded wing on the 12 became a plaque trap leading to caries and ultimately causing pain. How would you treat tooth 12 with reversible pulpitis?
- Consent patient
- LA
- Remove the caries
- Place pulp cap if necessary (setting calcium hydroxide)
- Restore with composite
- Review patients to check for pain resolution
31
What material is used in a metal wing of an adhesive bridge?
* Cobalt chrome or nickel chromium
32
The patient presents with missing upper laterals.
1. What type of bridge can you use to replace teeth? (2)
- Cantilever resin-bonded bridge. (Bond the tooth with a larger surface area to give better bond strength.)
- Fixed-fixed resin bonded bridge
33
Patient presents with missing upper laterals.
2. What abutment teeth would you use? (2)
- Central incisors and canines for fixed fixed
- Canine for cantilever
34
3. What are 4 pieces of information needed from patient for technician to make the bridge? (4)
- U and L impressions for casts
- Occlusal record
- Master impression with putty wash or impragum
- Facebow
- Bridge design and shade
- material they want the bridge in?
35
Give 2 alternative for replacing missing teeth, that is not a bridge? (2)
Implant
RPD
36
A patient present with a conventional bridge with retainer 11 and 22 and a pontic 21 complaining that it is loose. You suspect the retainer on 2 has debonded.
1. How can you detect this clinically/what might you see?
- Visual assesment may see gap between the bridge and abutment on 2
- Probe around the area checking fro gaps
- Is the bridge mobile
- Floss around the bridge
- Push and check for any air bubbles that may appear
37
List 4 design/preparation features that may can lead to the failure of a bridge.
| Poor question
- Poor abutment tooth health
- Poor corwn-to-root ratio
- Preparations were not parallel
- Over-tapered prep
38
Give 2 alternative treatment options for replacing the tooth?
* RPD
* Implant
39
Give 2 alternative bridge designs for this scenario? (A resin retained bridge is not an option as the adjacent teeth are prepped).
A patient present with a conventional bridge with retainer 11 and 22 and a pontic 21 complaining that it is loose. You suspect the retainer on 2 has debonded.
- Conventional cantilever
- Spring cantilever
40
A patient present with an amalgam with an overhang on its mesial surface?
1. How could this have been avoided?
- Good adaption of the matrix band and the use of wooden wedgets
41
What problems may occur due to this overhang?
- Act as a food and plaque trap which then allows for caries to develop and subsequently pain
- Can be dificult to clean furthering the problem
- Also cause gingivitis and periodontal disease
42
How do you mange this overhang?
- If possible adjust and repair
- Otherwise replace
43
How is the surface of a porcelain veneer treated in the lab to improve adhesion?
- Etched with hydrofluoric acid
44
If using a composite resin cement- what material ensures a good bond to the porcelain?
* Silane coupling agent
45
How does the silane coupling agent work chemically to bond between the porcelain and the resin?
* Oxide groups on the porcelain surface (hydrophilic) form a strong bond with the silane
* The other end of the silane molecule has a carbon-carbon double bond (hydrophobic) which reacts with the composite resin luting agent (hydrophobic)
* This creates a strong durable bond
46
Where else in dentistry is silane coupling agent used commonly?
In composites to bond the resins with the filler particles
47
When is a dual cured cement indicated?
- NEXUS (porcelain)
- Dual cured is indicated when you are cementing a thick opaque indirect restoration that light cure cannot/ would struggle to penetrate fully through
- This ensures that all of the cement is cured and decreases the chances fo failure
48
Crowns
1. What are the principles of crown preparation?
What do you want to achieve with your prep
- Preserve tooth tissue
- Retention and resistance form
- Structural durability
- Good marginal seal
- Preserve periodontium
- Aesthetics
49
What are the stages of crown preparation?
- Occlusal reduction
- Seperation
- Buccal reduction
- Lingual reduction
- Finishing with shoulder or chamfer
- Check occlusal surface and clearane
50
Give reduction for all metal crown, MCC, all ceramic?
* All metal- thickness >0.5mm, non-functional cusps at least >0.5mm, functional cusps at least >1.5mm, 0.5mm chamfer
* MCC- thickness> 1.3mm, non-functional cusps- 1.3mm, functional cusps- 1.8mm, incisal- 2-2.5mm, 0.5mm chamfer palatally & 1.3mm shoulder buccally
* All ceramic- non-functional cusps- 1.5mm, functional cusps- 2mm, incisal- 1.5-2mm, 1-1.3mm chamfer
51
What are the characteristics of an ideal post? (3)
- Parallel (avoids wedging and is more retentive)
- Non-threaded (the smooth surface incorporates less stress to the remaining tooth)
- Cement retained (acts as a buffer between masticatory forces and the post/tooth)
52
How can a post be assess for suitability?
- Is the tooth suitable, ideally not in molars (pulp chamber retention, nayyar core)
- Length. Atleast the same length as the crown. 1/2 of post in root should leave 4-5mm of rcf apically
- Width ,1/3 narrowest diameter of the root and with 1mm circumferential dentine
- Ferule 2mm dentine encircling tooth
| Says 1.5mm ferule but I would say 2mm
53
Give 3 post materials?
- Fibre post (glass or quartz)
- Metal post (type 4 gold, Ti)
- Ceramic post (zirconnia)
54
Give 3 core materials?
- Composite
- Amalgam
- GI
55
Patient presents to your practice with a debonded gold post and core crown, that is becoming a regular occurrence and you have seen the patient, 3 times in the last 6 weeks for this same issue.
1. Give three reasons why it has debonded off? (3)
- Poor moisture control and contamination of cement
- Incorrect cement materials
- Core or post fracture
- Root fracture (due to stresses) from unfavourable occlusion
- Untreatble cares has softened supporting tissues
- Inadequate taper of post
56
The fracture occurs at the junction of the post and core (core fractured from root), give 3 reasons why? (3)
- Inadequate ferrule (increases the likelyhood of fractures)
- Traumatic fracture due to stress or parafunctional habit
- Caries, weaking the supporting tooth tissue and causing fracture
57
What are the key features of a Nayyar core? (3)
- Retention is achieved from the undercut in the pulp chamber and divergence of canals
- 2-4mm of GP is removed and replaced with amalgam
- Immediate placement of definative resotration at same visit
58
What are 3 ways of removing a fractured post that is visible?
- Ultrasonic
- Mosquito forceps
- Masseran kit
59
Central incisor crown fractured completely off.
1. What are the treatment options at short notice?
- Adhesive cantilever with fractured crown as the pontic
- Vaccum formed splint with tooth
- Provisional post crown
- Provisional overdenture
60
Name three post materials? (3)
- fibre post (glass and carbon)
- Metal post (type 4 gold and Ti)
- Ceramic post (zirconia)
61
Give 4 indications for size of post measurement?
- Length, has to be atleast the same size of crown and extend half way down the root, leaving 4-5mm of GP apically
- Width, 1/3 of the root and 1mm of dentine circumfrentually
62
What may be used to cement the post?
- GI luting cement (aquacem)
- Adhesive resin luting cement
63
Give 3 methods for removing a fractured post?
- Ultrasonic
- mosquito forceps
- Masseran kit
64
Tooth Wear-
Patient attends with tooth wear.
1. Outline the different types of tooth wear?
Attrition - Physiological wear, tooth to tooth wear
Erosion - Tooth surface loss due to chemical process that doesnt involve bacteria. eg acidic drinks
Abrasion - Physical wear of the tooth surface through abnormal mechanical process independent of occlusion e.g. toothbrushing
65
What are the appearances of attritive, erosive and abrasive types of tooth wear?
* Attrition- lesions on occlusal and incisal contacting surfaces, early flat incisal edges and polished facet on occlusal planes, laterally shortening of crowns and flattened occlusal cusps with restorations showing same wear
* Erosion- surface detail lost, smooth and polished appearance of surfaces with cupping due to preferential dentine wear, bilateral concave lesions without chalky appearance, increased translucency of incisal edges, restorations sit proud of teeth, typically affects palatal up upper and occlusal of lowers
* Abrasion- wear pattern and site dependent on abrasive element, usually V shaped or rounded cervical lesions when lined to brushing habits or notching of the incisal edges if nail biting etc.
* Abfraction- cervical wear or cracks
66
How might tooth wear be monitored?
- Clinical photographs
- Study models
- BEWE index
67
What do the numbers in BEWE score mean?
## Footnote
0-3
0 - no wear
1 - intial loss of surface texture
2 - less than 50% hard tissue surface loss with distinct defect
3 - more than 50% hard tissue surface loss
Add up all the scores for each sextant then risk assess as none ((<2), low (3-8), medium (9-13), high (>14)
68
Name 3 ways the tooth could be desensitised. (3)
| Reduce dentine sensitivity
- Sensodyne toothpaste
- Fluoride varnish
- Seal and protect with DBA or GIC to cover exposed dentinal tubules
69
What is the DAHL technique?
- This is a method of treating toothwear
- With this method you use either restorations or a removable appliance to gain inter-occlusal space for restorations
70
Describe how the DAHL technique works?
- You place composites on the palatal surface of anterior teeth to prop open the bite (posterior disocclusion) and increase the OVD by 2-3mm
- Over 3-6 months the posterior teeth will erupt into this space and incisors will intrude slightly
- On removal of the composite you now have space between upper and lower anteriors which can be filled with definative restorations without occlusal reduction.
71
List 4 contraindication for the use of DAHL appliance? (4)
- Active periodontal health
- TMJ problems
- Bisphosphonate patients
- Dental implants which are ankylosed
72
You are about to restore the tooth wear with composite. Name 4 constituents of composite and give an example of each of the constituents? (4)
Resin - bis-GMA
Filler - glass
Silane - coupling agent
Photo intiator - camphorquinone
73
Why would you use RMGI instead of composite resin in a cervical abrasion cavity? (1)
- Moisture control is more difficult in this area and RMGI gives better results
- Good thermal properties
- No contraction on setting
74
1. What are the clinical signs of erosion?
- Wear on the palatal/lingual surface of the teeth
* Loss of surface detail
* Smooth or polished and flat surfaces
* Cupping (occlusal surfaces and incisal edges) as a result of preferential dentine wear
* Raised or proud restorations sitting above level of tooth surfaces
* Increased translucency of incisal edges
* (No tooth staining as tooth surface stripped off after staining)
75
What are the causative factors for erosive toothwear?
- Intrinsic factors - GORD, bulimia, hiatus hernia, persistant vomitting
- Extrinsic factors - Diet (carbonated drinks, low pH drinks, fruit juices vitamin C and phosphoric acid and alcohol
76
How erosion of teeth managed?
- Treat the cause
- Diet advice, to reduce the alcohol and carbonated drinks
- Then referral to GP for GORD and bilemia
- High fluoride toothpaste, FV to protect the teeth
- If sensitive seal and protect exposed dentine with GIC/composite
77
What is the shortened dental arch?
* There must be at least 20 teeth and 3-5 functioning units (pair of occluding premolar= 1 units & pair of occluding molars= 2 units)
78
Why is a shortened dental arch considered acceptable?
As this is enough teeth to provide suitable aesthetics, function and occlusal stability
79
What are the indications for a shortened dental arch?
- Patient accepting of their occlusion and aesthetics
- patient does not want or cannot have further dental treatment
- Teeth remaining have a good prognosis
- Patient has a stable occlusion, aesthetic look and functional bite
80
What are the contra-indications for a shortened dental arch?
- TMJ problems
- Poor prognosis of remaining teeth
- Untreated or advanced periodontal disease
- Signs of pathological toothwear as to reduce the effects of this need to have good posterior support
- Severe malocclusion class 2 or 3
81
How may a shortened dental arch be extended?
- RPD
- Cantilever bridge
- Implant
82
What are the 5 requirements of occlusal stability?
- Stable and even contacts in ICP
- Anterior guidance in harmony with posselts envelope
- Disocclusion of all posterior teeth on protrusion of mandible
* Disocclusion of posterior teeth on non-working side during lateral excursion
* Disocclusion of all posterior side on working side during mandibular lateral excursion
83
What are the signs of occlusal trauma?
- Pain but no signs of caries or infection
- Fractured restorations or teeth
- Increased tooth mobility
- TMD contributing factors
- Toothwear NCTSL
- SIgns of parafunction like tongue scalloping and linea alba
84
Draw and label Posselt’s envelope?
Is a record of the incisal edge movement of the mandible
85
What is RCP and what is its important?
Retruded contact position
- Important as used for re-organising the occlusion of patients that dont have clear ICP
86
What is Hanau’s quint?
* 5 factors (considered when setting teeth) that affect occlusal balanced articulation-
* The sagittal condylar guidance angle
* Inclination of the occlusal plane
* Compensating curves
* The cups height
* The incisal guidance angle
87
What is the thickness of shimstock?
8 microns
88
What is the average biological width?
2mm
- from alveolar crest to sulcus of gingiva(connective tissue 1mm and junctional epithelium 1mm)
89
Give 4 functions of a facebow?
- Mounting upper casts ONLY
- Takes a horizontal record of the hinge axis of the mandible
* Orientates the maxillary cast in the same relationship to the opening of the articulate as the hinge axis of the mandible in the patient; transfers the relationship between the maxillary teeth and the axis of rotation from the patient to the articulator
* Horizontal relationship is transferred from the patient to the articulator using the bow and the three bony reference points- relation between two heads of the condyle and the intercondylar distance allows the transverse action of rotation of the TMJ to be recorded
* The vertical relationship between the recorded horizontal axis of rotation and the upper teeth is set but the transfer jig and can be used to position the upper cast on the articulator
* Positions the upper cast vertically
* Transfers the angulation of the maxillary occlusal plane in relation to horizontal reference line
90
Name 4 types of articulator?
- simple
- Average value
- Semi adjustable
- Fully adjustable
91
Give 3 reasons why anterior guidance is preferred
- Easy to reproduce guiding contacts on anterior restorations compared to posterior restorations
- Protects posterior teeth and restorations
- May have a relaxing effect on the MOM so doesn't cause problems with the TMJ
- Canines are more stable and efficient during mastication, where as posteriors wear down a lot faster.
92
Implantology-
1. What factors does an implantologist consider before placing an implant?
- Smoking status
- Medical and drug history
- Alveolar bone quantity and quality
- OH and periodontal status
- Patient motivation, compliance and expectations
- Ginigval biotype (thin or thick etc)
- Occlusion
- Patient aestehtics (lip line)
- Dimension of space - occlusal space and BL and BP width of edentulous space
93
What bone dimensions are required for an implant and how are they best managed?
* 1.5mm horizontal bone around implant
* 3mm bone between implants
* >5mm space for papilla between alveolar crest of bone and contact point
* 7mm space between crowns of adjacent teeth
* At least 2mm vertical bone from adjacent structure e.g. IAN, maxillary sinus
* Ideally 3mm bone below proposed gingival margin
* Assessed with a CBCT
94
Give 3 alternative treatment options for a space, excluding implants?
- Accept space
- Orthodontics
- Bridge
- RPD
95
A 17-year old patient presents with congenitally missing 22 and 23.
1. The patient wants implants, what are the other options for replacement? (2)
- Orthodontics to close the space +/- restorative work
- Bridge, fixed-fxed (4 unit bridge)
- RPD
- Accept
96
A 17-year old patient presents with congenitally missing 22 and 23. 2. What problems would you face with aesthetics? (1)
- Due to the teeth being missing congentially, the other teeth will have drifted into the space meaning there isnt enough space to place two naturally looking teeth. This will have an effect on aesthetics.
- Opposing teeth may have over-erupted into the space, leaving problems with occlusion.
- The space is in the aesthetic zone
- If patient has a high smile line then margins of the restorations may be on show
97
A 17-year old patient presents with congenitally missing 22 and 23. 3. What problems would you face with function? (1)
- Canine teeth are important for canine guidance and therefore a high masticatory load will be placed on whatever restoration you place.
98
4. What general factors would a dentist consider before referring this patient for implant treatment?
## Footnote
Systematic way. MH, DH, SH, Occlusion, periodontal health
- Consider medical conditons, diabetes, clotting disorders, bisphosphonate use
- OH status, patient motivation, compliance and expectations
- Cost, do they smoke, history of contact sports?
- Bone levels
- Periodontal history and status
99
List three other factors, local to the site of the proposed implants which will be assessed for the implant treatment planning?
- Smile line
- Biotype
- Soft tissue adequacy
- Periodontal status and plaque control
- Quality and quantity of alveolar bone levels (bone width and height)
- Position and proximity of adjacent tooth roots (Is there enough space to put the implant?)
100
What are some aesthetic and function problems associated with having missing teeth?
- Teased due to gap
- Psychologically affected by having teeth missing especially if in the aesthetic zone
- May not smile
- Difficulty with mastication of food
- altered occlusion due to movement of teeth effecting bite
- Problems with speech (whistling)
- Tongue may move through the gap
101
Whitening-
1. Give 4 intrinsic and extrinsic causes of tooth discolouration?
Extrinsic
-Coffee
- Red wine
- Chlorohexidine
- Diet
- Smoking
Intrinisic
- Necrosis of the pulp (loss of vitality)
- Flurosis
- Tetracycline staining
- Dental materials (amalgam)
- Thalassemia or sickle cell, age, cystic fibrosis
102
How does vital bleaching with hydrogen peroxide work?
- Discolouration is caused by long chained organic chromogenic products within the tooth substance
- Hydrogen peroxide works by breaking these down by oxidising them into shorten products which are not coloured
103
What is the common acute ingredient in tooth whitening bleach? How is it related to hydrogen peroxide?
* Carbamide peroxide
* This tis the active agent and breakdown to produce hydrogen peroxide and urea
* 10% carbamine peroxide gives 3.6% hydrogen peroxide (16.7% carbamide peroxide- 6% peroxide- max allowed concentration)
* Hydrogen peroxide again break down to form water and oxygen and a free radicular which is the oxidising agent
104
Give 4 risks of vital bleaching?
* Sensitivity
* Relapse (wears off after 18 months)
* Allergy
* Soft tissue irritation
* Failed treatment- doesn’t work
105
1. What are the principles of cavity preparation?
* Identify and remove carious enamel
* Remove enamel to identify maximal extent of the lesion and the amelodentinal junction and smooth enamel margins
* Progressively remove peripheral caries in dentine- from the ADJ first then circumferentially deeper
* Only then remove deep caries over the pulp
* Outline form modification (enamel finishing, occlusion, requirement of the restorative material)
* Internal design modification (internal line and point angles, requirement of the restorative material)
106
2. What is the hybrid layer?
* Layer formed by interface of dentine collagen, bonding agent and composite resin
* Layer of dentine which has been conditioned to remove the loosely adherent smear layer and into which the adhesive resin has flowed to form a micromechanical bond within the tubeless and exposed dentinal collagen fibres and so a matrix of collagen and resin (forms by molecular entablement)
* The solubised dentine surface has no water content which allows the solvent primer to be the interface between the dentine and restorative material
107
3. What are the different types of dentine and how do they affect bonding?
* Primary dentine laid down during development- regular structure of open tubules which is favourable for hybrid formation and good for bonding
* Secondary dentine laid down during function- variable structure but usually sufficient to allow bonding
* Tertiary dentine; reactionary laid down due to mild stimuli and reparative due to intense stimuli- poorly organised/irregular tubules which may be occluded/sclerosed tubules with a higher mineral content which can make them less favourable for hybrid creation and the bond strength more unpredictable
108
4. What is the inorganic content percentage of dentine?
* 70% calcium hydroxyapatite
109
5. What are the features of a cavity for composite?
* No unsupported enamel
* No sharp internal line angles
* Beveled cavosurface margin angle to increase area for bonding (end on prisms- 90-120°)
* Flat occlusal floor
110
6. What technique are used for successfully placing composite?
* Flowable placed at base of cavity to decrease contraction stress
* Incremental placement to ensure low configuration factor
* No more than 2mm increments to avoid incomplete set (soggy bottom)
111
7. What are the features of a cavity for amalgam?
* Undercuts for retention
* Other retentive factors e.g. lock and key, grooves, dovetail/isthmus
* Greater that 2mm depth for sufficient strength
* Flat occlusal floor
* Cavosurface margin angle 90° (butt joint)
* No sharp internal line angles
* No unsupported enamel
