Restorative Flashcards
trauma to 12 + 11
11 has pulpal exposure of 2mm
discuss 4 steps of management of 11
assessment of pulpal vitality - if vital;
- LA + rubber dam
- partial pulptomy technique
- removal of 1-3mm of inflamed pulp tissues
- haemostasis should be achieved within 5 mins with use of cotton pellet
- apply biomaterial [CaOH] then definitive coronal restoration
if haemostasis not achieved, pulpectomy required
trauma to 12 - sub-alveolar fracture and is rendered unrestorable
why is a sub alveolar fracture important in making a tooth unrestorable
- lack of coronal tissue to bond to, seal to or place restoration
- inability to achieve proper isolation or moisture control
- lack of 2-3mm ferrule
- inability to take impression for indirect restoration
- if below alveolar crest then any restoration would violate biological width leading to chronic inflammation
- high risk secondary infection
alternatives to replacing 12 after XLA
implant
RPD
bridge
a new pt attends practice complaining of pain from tooth 12 and a de-bonded bridge
->what is the likely bridge design?
-> what is a reasonable differential diagnosis from pain to 12?
adhesive cantilever/(conventional??) bridge
RBB
pulpitis
fixed fixed cantilever bridge with 11 being the Pontic
it debonded from 12 but not 21due to 12 becoming a plaque trap, leading to caries and ultimately causing pain
what better alternative bridge design could this pt have and why would it be better
resin bonded/adhesive cantilever bridge from 21 only
if debonded - it would fall out and not remain as a plaque trap and causing caries
name 4 factors that could cause a bridge to de-bond
- unfavourable occlusion
- damaged/poor abutment teeth
- resin bridge not properly adhesively bonded
- poor moisture control during cementation
- parafunction like bruxism
- trauma
- poor OH
- improper tooth preparation
fractured 26 MOD amalgam in RCT tooth
-> what are some restorative options
MCC, onlay, XLA
if GP had been exposed in 26 with fractured MOD amalgam for 6 months, what would be your treatment and why
radiographic and clinical assessment of GP and presence of any pathology
Re-RCT due to exposure to the oral environment for over 3 months
features of a Nayyar core
used for posterior teeth before placing a crown
GP removed 2-4mm apically
Amalgam used to gain internal retention in undercuts in the canals and pulp chamber, rather than ferrule effect
No post needed
composite could also be used
name 2 restorative materials which can bond amalgam to tooth
RMGIC + GIC
which bond strength to tooth is better - amalgam or composite
composite - due to micro mechanical retention and chemical bonding between enamel + dentine with composite
list types of tooth wear
attrition
abrasion
erosion
abfraction
list the BEWE scores
0 - no erosive wear
1 - initial loss of surface texture
2 - distinct defect, hard tissue loss <50% of surface
3 - hard tissue loss >50% of the surface area
scored via sextant
risks;
<=2 - no risk
3-8 - low risk
9-13 - medium risk
>14 - high risk
name 3 routes or ways teeth can be desensitised
- fluoride varnish application 22,800 ppm
- fluoride toothpaste, desensitising toothpaste
- tooth mousse, CPP-ACP
- sealant with bond/GIC
what is the DAHL technique
how does it work
method of gaining space in localised anterior wear
localised appliance or composite placement to the palatal/occlusal of the anteriors to “prop open” the bite, allowing the posterior teeth to over-erupt over time to give increased occlusal dimension which can then be utilised for restorations
generally 2-3mm increase in OVD
4 contraindications of DAHL appliance
- active periodontal disease
- TMJ issues
- post-ortho
- bisphosphonate use
- implants
- existing bridges
- MRONJ risk ?
name 4 constituents of composite and give an example of each
- filler particles - glass/silica
- resin - BisGMA
- camphorquinone - light activator
- low weight demethacrylate - TEGDMA
- silane coupling agent - silane methoxy
why would you use RMGIC rather than composite resin in a cervical abrasion cavity
less moisture control needed [high moisture area]
less polymerisation shrinkage
fluoride release
ease of use
what are the options for replacement of central incisor crown fractured completely off to the root at short notice
- adhesive cantilever with fractured crown as Pontic
- provisional over denture
- vacuum formed splint with tooth
- provisional post crown with RCT
name 3 post materials
- metal: cast gold, SS, brass, Ti
- fibre: glass, quartz, carbon
- ceramic: aluminia, zirconia
indications for ideal size of post
- 4-5mm GP apically]
- post width no more than 2/3 of root
- at least 1/2 post in root
- minimum 1:1 post length to crown ratio
- 1mm circumferential dentine
- ferrule 1.5mm height
cementation materials for post
METAL POST - GIC, RMGIC
FIBRE POST - composite resin
give 6 methods for removing a post
- ultrasonic scaler vibration
- masseran
- eggler post remover
- tephan
- sliding hammer
- moskito forceps
what are the clinical signs of erosion
- enamel surface loss of detail
- flattening/smoothing
- dentine “cupping”
- increased enamel edge translucency
- bilateral concave lesions
causative factors of erosion
extrinsic: carbonated drinks, alcohol, sports drinks, citrus, fruit juice, sweets
intrinsic: GORD, bulimia, persistent vomiting
habits: swishing of drinks within mouth, no straw
treatment/management of erosion
removal of cause - diet advice
high fluoride - toothpaste, MW, varnish
desensitising agents - tooth mousse, GIC, composite
rule out medical causes or treat them - GORD give omeprazole, speak to GP regarding ED
habit changes - straw, stop rumination
what factors does an implantologist consider before placing an implant
- gum health
- bone status and quality, quantity
- smoking status
- oral hygiene
- pt motivation
- occlusion
- systemic health
- location of adjacent teeth/roots
- anatomical factors e.g. nerves, sinus
- aesthetic concerns
- angulation of other teeth
what bone dimensions are required for an implant and how are they best measured
Adequate bone height- ideally greater than 8mm
Adequate bone width- ideal greater than 5mm
3mm between implants
2m from adjacent structures
assessed via CBCT
how can you check if a bridge has been debonded
visual, probe, mobility, floss, discolouration, changes in occlusion,
what factors should be taken into consideration before placing a bridge
space available
condition of abutment teeth - caries, periodontal disease, mobility, tooth structure, enamel quality
occlusion
parafunctional habits e.g. bruxism
OH
17 y/o with congenitally missing 22+23
-> tx options
-> problems relating to aesthetics
-> problems relating to function
-> what would a dentist check before implant referral
-> what would an implantologist check
-> accept, RPD, bridge [4 unit fixed fixed], implants, orthodontics + restorative
-> teased for missing space
-> unfavourable occlusion for eating, speaking
-> overall health of teeth + gums, OH, smoking status, MH [osteoporosis, bisphosphonates, DM]
-> bone status, quality/quantity of bone, position of existing teeth, OH, proximity to structures, proximity of other teeth/roots
pt with large AM restoration replaced with composite due to secondary caries
radiograph a week ago had no caries or pathology after placement
-> give 5 causes of sensitivity to thermal stimuli and pain on biting they are experiencing
-> give 5 restorative management features that could prevent this from happening
- insufficient bonding of composite leading to micro gaps allowing bacterial ingress
- voids
- overpreparation
- mechanical irritation to the pulp when removing amalgam filling
- insufficient water with handpiece causing thermal stimuli and overheating to the pulp
- insufficient etching/bonding
- pulp exposure
- deep cavity
- uncured resins entering pulpal space
- lining material not used
- high in occlusion
- polymerisation contraction stress
- cracked tooth syndrome
- ensure proper bonding
- check occlusion with articulating paper
- incremental placements
- placement of lining material [CaOH]
- don’t over prep
- ensure proper composite curing
- proper isolation during tx
- better preparation
ideal characteristics of a post
- parallel
- non-threading
- cement retained
give 3 core materials
GIC
amalgam
composite
pt has a gold post and cure that has debonded several times
give reasons why
post fracture
core fracture
root fracture
post perforation
inadequate moisture control
inadequate post placement
post fracture occurs at the post-core junction
give reasons why
- stress concentration too high
- inadequate tooth structure/ferrule
- bruxism
- poor adhesion/cementation
- inadequate core bule up
- improper post alignment
- over prep of RC
- improper ratio
- effect of endodontic irrigants
- bacterial interaction
what are the principles of cavity preparation
- Identify and remove carious enamel
- Remove enamel to identify the maximal extent of the lesion at the amelodentinal junction & smooth the enamel margins
- Progressively remove peripheral caries in dentine starting at the ACJ, then circumferentially deeper.
- Only then remove deep caries over pulp
- Outline form modification: Enamel finishing, Occlusion, Requirements of the restorative material
- Internal design modification: Internal line and point angles, Requirements of the restorative material
what is the hybrid layer
collagen network interface between dentine and restorative material providing adhesion between tooth and material through primer and bonding agent
the micro mechanical bond between tubules + dentine collagen
what are the different types of dentine and how do they affect bonding
primary:
laid down in development, open tubules, good for bonding
secondary:
laid down during function, ok for bonding
tertiary dentine:
reactionary to trauma/stimuli, reparative, poor bonding due to poorly organised/sclerosed tubules
what is the inorganic content percentage of dentine
70% hydroxyapatite crystals
pt presents with a MCC in hand from their upper central
->what features of the tooth will make it successful/unsuccessful to tx
-> 3 short term options to replace tooth + explain
quality of tooth tissue, amount of remaining tooth tissue, pathology present, mobility, periodontal status, crown:root ratio, fracture of root
- recement as temporary to protect remaining tooth structure
- make provision crown with pro temp
- preformed provisional crown
missing upper laterals
->what type of bridges can be used
-> which abutment teeth can be used
-> 4 pieces of information needed for technician
-> alternatives to bridge
- mesial adhesive cantilever bridge
- adhesive fixed fixed bridge
- canine, central incisor
- bridge design, master impressions, bite registration, shade of teeth
- RPD, ortho, combined ortho + restorative, implant
how does the presentation of caries compare to a radiograph
generally, caries are deeper clinically
give 3 adv of composite over amalgam
- chemically bonds to tooth structure
- better aesthetics
- less preparation needed
- better marginal seal
- similar modulus of elasticity
- low thermal conductivity
- on demand set
what are the indications + contraindications for a resin retained bridge
- good quality enamel
- large bonding surface
- minimal occlusal load
- generally single tooth
- to simplify RPD
- long span
- poor/insufficient enamel
- heavy loads
- large soft/hard tissue loss
- poorly aligned/tilted/rotated teeth
- contact sports
how do you cement a porcelain bridge
RMGI or GI
silane coupling agent
how do you cement a metal bridge
RMGI or GI
10MDP
how is the surface of a porcelain veneer treated in the lab to improve adhesion
etched with hydrofluoric acid
if using a composite resin cement, what material ensures a good bone to the porcelain, and chemically how does this work
silane coupling agent
chemical covalent bonding where silane reacts with silica in porcelain [between OH groups]
give examples of when silane coupling agent is used in dentistry
composite: allows filler to preferentially bond to resin
bonding of ceramic crowns/onlays [emax e.g.]
when is a dual cure cement indicated
when cementing indirect restoration which light cure cannot penetrate fully
cementing posts
5 requirements of occlusal stability
- Stable and even contacts in ICP.
- Anterior guidance in harmony with the envelope of function.
- Disclusion of all posterior teeth in mandibular protrusion.
- Disclusion of posterior teeth on non-working side during mandibular lateral excursion.
- Disclusion of all posterior teeth on working side during mandibular lateral excursion.
what are the signs of occlusal trauma
- pain not explained by infection
- fractured restorations
- TMD
- scalloping, pronounced lines alba
- wear facets
- cracked tooth syndrome
- tooth mobility
- widening PDL
- NCTSL
- receding pulp chambers in young pt
name 4 types of tooth wear and describe their appearance
attrition:
flattening of incise edge + occlusal planes
erosion:
“cupping” defects, smooth/polished, surface detail lost
abrasion:
V-shaped/rounded lesions, sharp enamel edge margin where dentine worn away, notching of incisal edge
abfraction:
cervical wear/cracks, V-shaped loss under tension areas, sharp ACJ
how can tooth wear be monitored
- clinical photographs
- study models
- BEWE index
- Smith and Knight
what percentage of adults have tooth wear
??? 60%
give 4 intrinsic + extrinsic causes of tooth discolouration
intrinsic:
- fluorosis
- tetracycline
- loss of vitality
- restorative materials
- amelogenesis/dentinogenesis imperfecta
- trauma
- ageing
extrinsic:
- coffee, tea
- smoking
- chromogenic bacteria
- CHX
How does vital bleaching with hydrogen peroxide work?
“Hydrogen peroxide oxidizes pigmented molecules (chromophores) within enamel and dentin. It breaks down into free radicals that penetrate the tooth structure, breaking apart stains and lightening the tooth
What is the common active ingredient in tooth whitening bleach? How is it related to hydrogen peroxide?
Carbamide peroxide
it breaks down into hydrogen peroxide and urea when applied, with hydrogen peroxide being the actual whitening agent.
Typically, 10% carbamide peroxide releases about 3.5% hydrogen peroxide, which then oxidizes stains within the enamel and dentine
16.7% carbide peroxide = 6% hydrogen peroxide max
4 risks of vital bleaching
- sensitivity (60%)
- relapse
- soft tissue irritation
- may not work
- enamel damage
- uneven whitening
what are the features of a cavity for composite placement
- no unsupported enamel
- smooth/rounded internal line angles
- bevel cavosurface margin to increase area for bonding
- conservative preparation
what techniques are used for successfully placing composite
- flowable at base to decrease concentration stress
- incremental placement to have low configuration factor [2mm or less]
- moisture control
what are the features of a cavity for amalgam placement
- undercuts for retention
- other retentive factors e.g. lock + key, grooves, dovetail/isthmus
- > 2mm depth for sufficient strength
- flat occlusal floor
- cavosurface margin 90*
- no unsupported enamel
pt presents with discoloured anterior tooth
it isn’t sensitive or symptomatic but had a blow to it a few years ago and discolouration is getting worse
-> how would you find the aetiology
-> what special investigations
careful history, trauma, history, dental history
examination - mobility, adjacent teeth, caries assessment
what treatment options are there for discolouration
- accept
- vital bleaching
- micro abrasion
- icon resin infiltration
- non vital bleaching
- composite bonding
- porcelain veneer
name 4 design/preparation features that may lead to debonding of a conventional fixed fixed bridge with 21 being Pontic
- unsuitable abutment choice
- over preparation
- under preparation
- no parallelism of the abutments
- over tapered preparation
- poor cementation of abutments
- high occlusal load area
- poor abutment health [caries, perio]
- unfavourable occlusion
- parafunction [bruxism]
11-21-22 fixed fixed conventional bridge
it has been debonded
give 2 alternative bridge designs
[resin retained not an option due to the adjacent teeth already prepped]
- conventional cantilever
- spring cantilever
- fixed moveable bridge
name the sites on posselts envelope
ICP = intercuspal position
E = edge-edge
Pr = max protrusion
T = maximum opening
R = retruded axis position
RCP = retruded contact position
what is RCP and what is it’s importance
- first tooth contact when mandible is in the retruded axis position
- condyles in most superior position in mandibular fossa
- it is a reproducible position for registration in complete dentures
what is Hanna’s quint
used for setting teeth, determining pt occlusion/bite
- condylar guidance
- incisal guidance
- occlusal plane
- compensating curve
- cuspal inclination
what is the thickness of shimstock
8 microns
what is the average biological width
approx 2mm from alveolar crest to sulcus of gingiva
overhand present from AM restoration mesially
-> how can this be prevented
-> what problems may this cause
-> how to manage
correct adaptation of matrix, wedge placed, adequate amalgam condensing
plaque trap, food packing, secondary caries, gingivitis, periodontal disease, fracture of amalgam if thin section
replace amalgam, adjust with bur
4 functions of facebow
- records relationship between maxilla and TMJ/condyle
- allows setting on articulator based on this position
- allows mandibular cast to be mounted in relation
- used when changes in occlusion
- transfers functional jaw movement
4 types of articulators
- simple hinge
- average value
- semi-adjustable
- fully adjustable
give 3 reasons anterior guidance in preferred
- easy to reproduce
- protects posterior teeth/rests
- easy on muscles
what are the 6 principles of crown preparation
- Preserve tooth structure.
- Retention and resistance form.
- Structural durability.
- Marginal integrity.
- Preserve periodontium.
- Aesthetics
why use a RMGIC liner rather than GIC
- improved bonding to tooth structure, higher mechanical strength
- better compressive strength
- better wear resistance
- demand set
- lower solubility
drawbacks for GI as luting cement
- shorter setting time
- lower strength/wear resistance
- more soluble
what luting cements would you use for;
-> metal post core
-> carbon fibre post
metal = GI, RMGI
carbon fibre = composite resin, dual cure
ideal properties of a luting cement
- low solubility
- high compressive strength
- ease of use
- biocompatible
- good bond strength
- low thickness <25 microns
- good working + setting time
- fracture/wear resistance
drawbacks of RMGI as luting cement
- lower bond strength compared to resin
- more prone to wear and solubility
- contains HEMA = absorbs + swells, cytotoxic to pulp
how do you bond a porcelain veeneer
etch with hydrofluoric acid and use silane coupling agent
allows bonding to resin luting cement
How do you bond non-precious metal? [e.g. crown/onlay]
sand blast with aluminium oxide
4MDP or 4META
What are the components of temp bond?
zinc oxide base
eugenol accelerator
Can you bond zirconia?
it cannot be etched due to being a non-silica ceramic
needs to be sandblasted then primed with monomer such as 4MDP
why are lithium disilicate crowns so strong
glass-ceramic material with interlocked crystals, reinforced with leucite crystals providing excellent mechanical strength and fracture toughness and fracture resistance. The crystals help stop crack propagation
-> what type of material is vitrebond
-> why should it be used over GIC as a lining material
RMGIC
higher mechanical strength, lower solubility, command set
why shouldn’t you use GI as a luting agent
may absorb moisture, weak mechanically
