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SAQs for dentistry > Restorative Dentistry > Flashcards

Restorative Dentistry Flashcards

1
Q

5 causes on instrinsic discolouration of vital teeth

A
  • trauma resulting in pulpal death
  • fluorosis
  • tetracycline staining
  • amelogensis imperfecta
  • dentinogenesis imperfecta
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2
Q

improving tooth colour

methods that need tooth prep

methods that do not need prep

A

methods needing prep

  • veneer
  • crown

methods not needing prep

  • bleaching
  • microabrasion
  • composite veneers
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3
Q

how to remove extrinsic stains from tooth surface

A

polishing the surface with pumice slurry and water or prophylaxis paste

ultrasonic cleaners

bleaching

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4
Q

primary dentine

A

formed before eruption or within 2-3 years after eruption and consists mainly of circumpulpal dentine

inc mantle dentine in the crown and the hyaline layer and granular layer in the root

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5
Q

secondary dentine

A

regular dentine formed during the life of the tooth and laid down in the floor and ceiling of the pulp chamber

physiological type of denitne after the full length of root has formed

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6
Q

tertiary dentine

A

divided into reparative and reactionary denitne - both laid down in response to noxious stimuli

reactionary dentine is laid down in reposne to mild stimuli whereas reparative dentine is laid down directly beneath the path of injured dentinal tubules as a response to stronger stimuli and are irregular

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7
Q

difference between internal and external resorption

A

internal resorption starts within the pulp chamber of a tooth

external resorption starts on the surface of the tooth, most commonly the root surface

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8
Q

internal resorption in vital or non vital teeth

A

only in vital teeth (or partially vital)

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9
Q

external resorption in vital or non vital teeth

A

can occur in both vital and non vital

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10
Q

signs of ankylosis

A
  • different sound from a normal tooth when it is percussed, often described as a cracked china sound
  • lacks periodontal membrane space on a radiograph
  • has no physiological mobility
  • may become infraoccluded as the jaw grows around it
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11
Q

BPE 0

finding on probing

tx

A

coloured area of probe is completely visible, no calculus and no gingival bleeding

no need for tx

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12
Q

BPE 1

finding on probing

tx

A

coloured area is completely visible, no calculus but bleeding on probing

OHI

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13
Q

BPE 2

finding on probing

tx

A

coloured area is completely visible; supra or sub gingval calculus detected or overhanging restorations

OHI; elimination of plaque retentive areas; professional mechanical plaque removal

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14
Q

BPE 3

finding on probing

tx

A

coloured area partially visible

OHI; elimination of plaque retentive factors; PMPR

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15
Q

BPE 4

finding on probing

tx

A

coloured area completely disappears indicating proving depth of >5.5mm

referral may be needed

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16
Q

general risk factors for periodontal disease

A
  • poor access to dental care
  • smoking
  • systemic disease e.g. diabetes
  • stress
  • history of periodontal disease
  • genetic factors
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17
Q

localised factors for periodontal disease

A
  • overhanging restorations and defective restoration margins
  • partial dentures
  • oral appliances
  • calculus
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18
Q

gingival recession risk factors

A
  • trauma - excessive toothbrushing, digging fingernails into gingiva, biting pencils
  • traumatic incisor relationship
  • thin tissues
  • prominent roots
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19
Q

fluoride effect on teeth prior to eruption

A

teeth have more rounded cusps and shallower fissures

crystal structure of the enamel is more regular and less acid soluble

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20
Q

effect of fluoride on teeth after eruption

A

decreases acid production by plaque bacteria

prevents demineralisation and encourages remineralisation of early caries

remineralised enamel is more resistant to further acid attacks

thought to affect plaque and pellicle formation

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21
Q

consequences of fluoride overdose

A

enamel fluorsis

mottling

pitting

GI toxic effect

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22
Q

recommended water fluorid conc for optimal caries prevention

A

1ppm in UK

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23
Q

safely tolerated dose F

A

1mg/kg body weight

level below which symptoms of toxicity are unlikely to occur

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24
Q

potentially lethal dose F

A

5mg/kg body weight

lowest dose associated with fatality

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25
Q

certainly lethal dose

A

32-64mg/kg body weight

at this dose survial is unlikely

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26
Q

pulpitis

A

inflammation of the pulp

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27
Q

reversible pulpitis is a X pain

set off by X and is X localised and lasts X

A

reversible pulpitis is a SHARP pain

set off by HOT/COLD AND SWEET THINGS and is POORLY localised and lasts SEVERAL SECONDS

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28
Q

irreversible pulpitis is a X pain

set off by X

it is X localised and lasts X

A

irreversible pulpitis is a THROBBING pain

set off by BITING OR SPONTANEOUSLY

it is WELL localised and lasts SEVERAL HOURS

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29
Q

nerve fibres found in the pulp

A
  • A beta fibres - large, fast conducting proprioceptive fibres
  • A delta fibres - small sensory fibres
  • C fibres - small unmyelinated sensory fibres
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30
Q

tx for irreversible pulpitis

A

root canal tx

extraction

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31
Q

pts can have thermal sensitivity after placement of a resotration

theory for this

A

theory of pulpal hydrodynamics

  • fluid moves along dentinal tubules and when there is a gap between the restoration and dentine, fluid will slowly flow outwards
  • decrease in temperature leads to a sudden contraction in this fluid and so inc flow - pt feels as pain
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32
Q

how can restorative techniques limit thermal senstitivty

A

hydrodynamic theory - aim to seal the dentine and inc the integrity of the interface between the dentine and the resotrative material

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33
Q

cavity sealers role

A

prevent leakage of the interface of the restorative material and the cavity walls and to provide a protective coating to the cavity walls

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34
Q

cavity sealers types

A
  • varnishes e.g. synthetic resin based material or natural resin or gum
  • adhesive sealers which also bond at the interface between teh restorative material and cavity walls e.g. GI luting cement
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35
Q

what is microleakage

A

passage of bacteria, fluids, molecules or ions along the interface of a dental resotration and the wall of the cavity preparation

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36
Q

consequences of microleakage

A
  • marginal discolouration of restorations
  • secondary caries
  • pulpal pathology
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37
Q

management of pulpal expsoure in a vital tooth

A

direct pulp capping

  1. if tooth not already isolate - isolate with dental dam
  2. dry the cavity
  3. place CaOH over the exposure
  4. cover with cement/liner e.g. Glass ionomer
  5. restore as normal
  6. inform the pt
  7. arrange a review
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38
Q

aim after direct pulp cap

A

what may happen:

  • dentine bridge will form
  • pulp will remain vital
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39
Q

contraindication to pulp capping

A
  • non vital tooth
  • history of spontaneous pain - irreverisble pulpitis
  • evidence of periapical pathology
  • large exposure
  • contamination of the exposure with saliva, oral flora or bacteria from teh caries

older the pulp the less likelihood of success

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40
Q

adv of rubber dam in restorative dentisty

A
  • isolation and moisture control - esp imp for moisture sensitive techniques e.g. acid etch before composite restoration
  • prevention of inhalation of small instruments e.g. during endo tx
  • improved access to the tooth - no soft tissues/tongue in way
  • pt do not swallow irrigants
  • soft tissues protected from potentially noxious materials
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41
Q

restorative material able to bone to tooth tissue without surface pretreatment

A

glass ionomer

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42
Q

how can GI adhesion be improved

A

using a polyalkenoic acid conditioner

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43
Q

how does GI bond to teeth

A
  • micromechanical interlocking - hybridisation of the hydroxyapatite coated collagen fibril network
  • chemical bonding - ionic bonds form bewtween the carboxyl groups of the polyalkeonic acid and the calcium in HA
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44
Q

adv of GI

A
  • bonds to tooth tissue
  • releases F
  • quick to use as limited pretreatment of teh tooth surface is needed
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45
Q

clinical uses of GI

A
  • premanent direct resotrative material in deciduous and permanent teeth
  • temporary restoration
  • luting cement
  • cavity lining or base
  • core build up material
  • retrograde rooth filing material
  • pit and fissure sealant
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46
Q

‘smear layer’

A

when tooth tissue is cut the debris is smeared over the tooth surface

this is the smear layer - contains any debris produced by the reduction or instrumentation of dentine, enemal or cementum

calcific in nature or contaminant that precludes the interaction of restorative material with underlying pure tooth tissue

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47
Q

dentine can be treated/conditioned with acid

why is this

A

removes most of the hydroxyapatite and exposes a microporous network of collagen

smear layer is altered or dissolved

bonding that results is diffusion based and relies on the exposed collagen fibril scaffold being infiltrated by the resin

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48
Q

why are primers needed

A

the denture surface after conditioning is difficult to wet with the bonding agents

the primer transforms this surface froma hydrophillic state into a hydrophobic state that allows the resin to wet and penetrate the exposed collagen fibres

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49
Q

what is the hybrid layer

A

hybrid layer is the area in which the resin of the adhesive system has interlocked with the collagen of the dentine, providing micromechanical retention

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50
Q

dentine bonding agents role

A
  • form resin tags in the dentinal tubules
  • stabilise the hybrid layer
  • form a link between teh resin primer and the restorative material
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51
Q

aims of obturating a root canals

A
  • prevent reinfection of teh cleaned canal
  • prevent periradicular exudate from entering into the root canal
  • seal any remaining bacteria in the root canal
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52
Q

methods for filling a root canal with GP

A
  • single cone method
  • lateral condensation - warm or cold
  • thermomechanical compaction
  • vertical condensation
  • thermoplasticised GP method
  • carrier based techniques
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53
Q

causes of intra radicular failure of root canal tx

A
  • necrotic material left in the canal
  • bacteria left in the root canal system (lateral or accessory canals)
  • contamination of the canal during treatment
  • loss/lack of coronal seal
  • persistent infection after treatment
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54
Q

causes of extra radicualr failure of RCT

A
  • root fracture
  • radicular cyst
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55
Q

indications for apicepctomy (surgical endo)

A
  • infection due to a lesion that requires biopsy e.g. radicular cyst
  • instrument stuck in canal with residul infection
  • impossible to fill apical third of root canal due to anatomy or pulp calcification
  • perforation of root
  • post crown with excellent margins but persistent apical pathology
  • infected, fractured apical third of root
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56
Q

acid etching of enamel

A

application of mild acid to the surface of enamel causes dissolution of about 10um of the surface organic component, leaving a microporous surface layer up to 50um deep

suface is thus pitted, and the unfilled resin of the restorative material is able to flow into the irregularities to form resin tags that provide micromechanical retention

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57
Q

common etchant

A

30-40% Phosphoric acid

gel or liquid

gel longer to wash away but less likely to run onto areas where etch not wanted

can be combined with dentine conditioner

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58
Q

etch applied for

A

15-20 secs

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59
Q

after applying etch

A

wash away with watwr for at least 15 secs

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60
Q

what can damage the etch enamel surface and reduce the efficacy of bonding

A

blood and saliva, and mechanical damage may occur by probing the area

rubbing cotton wool over it to dry it or by scraping across teh surface with a tip or an instrument

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61
Q

total etch technique

A

involves using an acid to etch the enamel and condition the dentine at the same time

commonly used acids: phophoric acid (10-40%), nitric acid, maleic acid, oxalic acid adn citric acid

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62
Q

20 yo women, CO gaps, missing laterals

tx options

A
  • orthodontic tx to close the spaces
  • removable partial denture
  • adhesive bridges
  • conventional bridges
  • implants
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63
Q

20 yo women, CO gaps, missing laterals

orthodontic tx to close spaces

adv and disadv

A

adv

  • no artifical teeth needed
  • pt does not need restorative tx to replace teeth

disadv

  • may take long time to complete
  • canines may not provide a good contact against the central incisors
  • bleaching and restoration of the canines may be needed to make them look like incisors and recontoring of ginigval margin
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64
Q

20 yo women, CO gaps, missing laterals

RPD

adv and disadv

A

adv

  • quick
  • cheap
  • does not require removal of tooth tissue

disadv

  • not ideal in young pt
  • removable
  • may need replacing in long term
  • may compromise gingival and oral health if OH and diet not idea
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65
Q

20 yo women, CO gaps, missing laterals

adhesive bridges

adv and disadv

A

adv

  • fixed tooth in place
  • good aesthetics
  • no/min prep of adj teeth

disadv

  • may debond
  • needs favourable occlusal clearance
  • may need replaced
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66
Q

20 yo women, CO gaps, missing laterals

conventional bridge

adv and disadv

A

adv

  • fixed tooth in place
  • good aesthetics

disadv

  • requires destruction of adj teeth
  • impairs cleansabilty
  • may need replaced
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67
Q

20 yo women, CO gaps, missing laterals

implants

adv and disadv

A

adv

  • permanent solution
  • good aesthetics
  • like having real tooth

disadv

  • costly
  • may need bone graft
  • requires surgery
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68
Q

what is composite

A

type of restorative material

made of: oragnic resin matrix, an inorganic filler and a coupling agent

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69
Q

traditional composite

adv and disadv

A
  • good mechnical properties
  • surface roughness and difficult to polish
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70
Q

microfilled resin composite

adv and disadv

A

very good surface polish

poor wear resistance

unsuitable for load beading areas

high contraction shrinkage

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71
Q

hybrid composites

adv and disadv

A

good mechancial properties

good surface polish

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72
Q

small particle hybrid composites

A

good mechnical properties

very good surface polush

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73
Q

how to finish and polish a composite

A

involves shaping and smoothing the restoration to teh anatomical form and polishing imparts a shine to the surface

smoothest suface is achived when composite is polymerised against an acetate strip with no polishing - but leaves a surface with a v high resin content that is not resistant to wear

for polishing:

  • diamond and carbide burs are used for gross finishing
  • rubber cups with abrasive materials of diffreing coarsness
  • flexible abrasive discs - most to least (light to dark)
  • finishing strips for interproximal areas
74
Q

risk factors for root caries

A
  • exposure of the root surface (pocketing, gingival recession or attachment loss)
  • cariogenic diet
  • decreased salivary flow (medicaments, previous radiotherpy, drugs, diabetes, ageing)
  • poor oral hygiene - inaccessible areas e.g. perio pockets, decreased manual dexterity, lack of access to dental healthcare or dental health low priorty, remoable prosthesis, poor restorations
75
Q

materials commonly used for Class V lesions

A

GI

RMGI

composite

amalgam

76
Q

management of pt with multiple root caries lesions

A

elimination of active infection (remove caries and place resotrations) and preventative measures:

  1. identify any risk factors that can be corrected
  2. oral hygiene advice
  3. dietary analysis and advice
  4. periodontal tx as necessary
  5. F tx in teh surgery (duraphat application) or at home application (rinses)
  6. recall
77
Q

adv of bonded amalgam restoration vs non bonded amalgam

A
  • dec in microleakage
  • less destructive in tooth tissue
  • may limit need for dentine pins
  • may inc fracture resistance of restored teeth
  • transmits and distributes force better
  • less post op sensitivity due to better sealing of the margins
78
Q

materials that can bond to tooth tissue

A
  • GI
  • composites
  • hybrid restorative materials e.g. RMGI, compomers
  • ceramics - using special cements
79
Q

pretreatment of anterior crowns

A

conventional ceramics that are silica based are tx with hydrofluoric acid and ammonium bifluoride

  • can also be sandblasted or air arbraded
  • often tx with silane coupling agent

alumina and zirconium oxide ceramics are surface roughened with air abrasion and then coated with silicate

80
Q

materials for primary impression complete dentures

A

alginate

compound - thermoplastic

impression putty

81
Q

hydrocolloid imp materials division

A

reversible - agar

irreversible - alginate

82
Q

synthetic elastomeric imp materials divided into

A

elastomers

polysulphides

polyethers

silicones (addition or condensation cured)

83
Q

mucostatic impression

A

impression with mucosa in its resting state

provides a good fit at rest and therefore good retention

i.e. most of the time but when the pt chews the denture will tend to rock around teh most incompressible areas e.g. palatine torus

84
Q

mucocompressive impression

A

taken when the denture bearing area is subjected to compressive force

denture is maximally stable during fuction but not at rest

85
Q

RVD

A

resting vertical dimension

measure of vertical height of the pt lower face and is measures as the distance between two abritary points (one related to maxilla and other mandible) with pt at rest

86
Q

OVD

A

occlusal vertical dimension

similar measure to RVD but taken when pt teeth in occlusion

87
Q

FWS

A

freeway space

difference between RVD and OVD - vertical gap between the pt teeth at rest

88
Q

factors that may affect rest jaw position

A
  • stress
  • head posture
  • pain
  • age
  • neuromuscular disorders
  • bruxism
89
Q

group function

A

during lateral excursion there is contact between several upper and lower teeth on the working side and no contacts on teh non-working side

90
Q

canine guidance

A

during lateral excursion there is contact between upper and lower canine teeth on the working side only and no contact on the non working side

91
Q

balanced occlusion

A

means simultaneous contacts between opposing artifical teeth on both sides of dental arch

92
Q

aim for occlusion in C/C

A

balanced occlusion

93
Q

difference between balanced occlusion and balanced articulation

A

balanced articulation is simulatenous contact of opposing teeth in centreal and eccentric positions as the mandible moves

i.e. it is a dynamic relationship

whereas balanced occlusion is a static situ

94
Q

factors affecting occlusion in protrusive movements in C/C

A
  • incisor guidance angle
  • cusp angles of posterior teeth
  • condylar guidance angle
  • orientation of occlusal plane
  • promenence of compensating curve
95
Q

immediate dentures

adv and disadv

A

adv

  • pt never without teeth - psychological adv
  • aesthetics - pt never without teeth
  • artifical teeth can be set in the same position as natural ones
  • soft tissue support
  • easier to register jaw relations as they are taken when the pt had teeth
  • bleeding easier to control after extractions

disadv

  • denture may not fit
  • will need relining/copying or remaking
  • will not fit when the alveolus remodels
  • usable to try in
  • may need many visits for adjustments
96
Q

flanged immediate denture

A

flanged periphery like a normal complete denture

good retention and will make future adjustments easier

disadv is that the lip may be over supported/appear too bulbous

97
Q

open faced immediate denture

A

no buccal flange and the denture teeth sit at the edge on the extraction sockets of the natural teeth

adv is that it can be used when there are large undercuts, often good aesthetics initally

disadv retention is poor and when resorption occurs a gap appears between ginigval margin of the denture teeth and mucosa

98
Q

methods to adjust fit of immediate denture

A
  • relining
  • rebasing
  • copy dentures
  • total remake
99
Q

dental surveyor

and aim of surveying

A

instrument used to determine relative parallism of 2 or more surfaces of teeth or other parts of the cast of dental arch

aims to identify

  • most desirable path of insertion that will eliminate or minimise interference to placement and removal
  • tooth and tissue undercuts
  • tooth surfaces that are or need to be parallel so that they act as guide planes during insertion and removal
  • measure areas of teeth may be used for retention
  • whether tooth and bony area of interference need to be eliminated surgically by selecting different paths of insertion
  • undesirable tooth undercut that needs t be avoided, blocked out or eliminated
  • potential sites for occlusal rests and where they need to be prepared
100
Q

dental articulator

A

instrument used to reproduce jaw relationships and movements of the lower jaw relativet to the upper jaw

casts of both upper and lower are mounted on

101
Q

facebow

A

instrument that measures teh relationship of either the maxillary or mandibulr arch to the intercondylar axis and ise used to transfer these measurements to the articulator

means that the articulated casts will have the same relationship to the hinge axis of the articulator as the teeth with the intercondylar axis

102
Q

muscles which may affect the peripheral flanges of a C/C

A

geniohyoid

orbicularis oris

mentalis

mylohyoid

buccinator

palatpharyngeus

palatoglossus

103
Q

location of posterior margins of upper complete denture usually

A

anterior to the fovea palatine

104
Q

what is post dam and its role

where is it

A

raised lip on the posterior boder of the fit surface of an upper complete denture

compresses teh palatal soft tissue to form a border seal

usually lies at the junction of the non-moveable hard palate(anteirorly) and moveable soft palate (posteirorly)

105
Q

neutral zone

A

area between tongue, lips and cheeks where displacing forces of the muscles is minimal

the ideal area into which a prosthesis should be placed to minimise displacing forces

106
Q

kennedy class I

A

bilateral edentulous areas located posterior to natural teeth

107
Q

kennedy class II

A

unilateral edentulous areas located posteriot to the remaining natural teeth

108
Q

kennedy class III

A

a unilateral edentulous area with natural teeth remaining both anterior and posterior (bounded saddle)

109
Q

kennedy class IV

A

single, but bilateral (crossing midline) ednetulous area located anterior to remaining natural teeth

110
Q

stages in designing a partial denture

A
  1. outline saddle areas
  2. place occlusal rests seats
  3. place clasps for direct retention
  4. place indirect retainers
  5. connect the denture
111
Q

direct retainer in partial denture is

A

any element of a partial denture that provides resistance to movement of the denture awy from the supporting tissues is a direct retainer

112
Q

2 types of clasp in partial denture

A

gingivally approaching

occlusally approaching

113
Q

what is in a clasp unit? why?

A
  • clasp
  • some form of support, usually an occlusal rest
  • some form of reciprocation

support will allow loads to be transferred along the long axis of teeth

also enable the clasp arm to be accurately located in the undercut on the tooth

reciprocation is needed as all clasps on teeth must be balanced by something on the opposite surface to act as a balance - prevent inadvertent force being applied to a tooth in one direction

114
Q

indications for copy dentures

A
  • occlusal wear on a set of previously successful complete dentures
  • need for replacement denture base material
  • pt was initially given immediate dentures and they need to be replaced
  • pt has a set of complete dentures that they have been happy with but are now unretentive/worn, esp elderly pts who may find it hard to adapt to a completely new set of dentures
  • make spare set of dentures
115
Q

adv of copy dentures

A
  • simple clinical steps, quicker than starting from scratch
  • reduced number of lab steps - no special trays or record blocks
  • pt is never without denture
  • original dentures not altered in any way
  • more predictable pt acceptance
116
Q

X is tooth surface loss from non bacterial X attack. Smooth X surfaces are seen with restorations standing X. Tooth surface loss of the X surfaces of the upper incisors is seen in cases of gastric reflux and vomitting

A

erosion is tooth surface loss from non bacterial chemical attack. Smooth plaque-free surfaces are seen with restorations standing proud. Tooth surface loss of the palatal surfaces of the upperincisors is seen in cases of gastric reflux and vomitting

117
Q

X is physical wear of a tooth by an external agent and may result in class V cavities at the X.

A

abrasion is physical wear of a tooth by an external agent and may result in class V cavities at the gingival margin.

118
Q

X is physical wear of a tooth by another tooth, and its commonly affects X and X surfaces

A

attrition is physical wear of a tooth by another tooth, and its commonly affects occlusal and interproximal surfaces

119
Q

abfraction lesions are thought to be due to a combination of X and occlusally-induced tooth X

A

abfraction lesions are thought to be due to a combination of abrasion and occlusally-induced tooth flexure

120
Q

possible causes of severe erosion in 16 y.o. girl

A
  • vomitting - bulima nervosa
  • excessive fizzy drinks

less likely GORD, pregnancy

121
Q

how to determine working length of a root canal

A

electronic apex locator

working length radiograph with an intrument in the canal

122
Q

benefits of crown down method for root canal prep

A
  • better access
  • flaring of coronal part first removes restrictions and helps prevent instruments binding short of working length
  • coronal part is usually where most of the infected material is present
    • if removed and cleaned first it limits the chance of spreading the infected material to the apical and periapical tissues
  • estimate the working length then change the coronal part of prep it may inadvertently alter the length
  • coronal prep first allows irrigants to gain access to more the root canal system
123
Q

commonly used irrigants in RCT

A
  • sodium hypochlorite
  • EDTA
  • CHX
124
Q

ideal properties of root canal filling

A
  • capable of sealing teh canal apically, laterally and coronally
  • radiopaque
  • bacteriostatic
  • not irritate the periradicular tissues
  • easy to handle, inert and if needed removable
  • impervious to moisture
  • dimensionally stable
125
Q

overdenture Vs onlay denture

A

overdenture derives support from one or more abutment teeth by completely covering them beneath its fitting surface

onlay denture is a partial denture that overlays the occlusal surface of all or some of the teeth - often used to inc OVD

126
Q

overdenture adv

A
  • preservation of alveolar bone around retained roots
  • improved stability, retention and support
  • preserved proprioception
  • decreaded crown-root ratio which reduces damaging lateral forces and reduces mobility in teeth with recued periodontal support
  • inc masticatory force
  • psychological benefit of not losing all teeth
127
Q

overdentures useful in

A
  • severe tooth wear
  • pt with hypodontia
  • cleft lip and palate pt
  • motivated pts with good OH
128
Q

osseointegration

A

direct strutural and functional union between ordered living bone and the surface of a load carrying implant

129
Q

factors to consider for abutment teeth selection

A
  • should ideally be bilateral and symmetrical with a min one toooth space between them
  • order of preference: canine, molars, premolars, incisors
  • healthy attached gingivae and periodontal support, min mobility
  • done root surface 2-4mm above gingival margin
  • root canal tx may be needed
130
Q

situations that can use implants

A
  • single tooth replacement
  • bridge abutment
  • support for overdenture
  • support facial prosthesis and hearing aids
  • orthodontic anchorage
131
Q

pt related factors that may affect the success of implants

A
  • oral hygiene
  • periodontal disease
  • previous radiotherapy
  • smoking
  • bisphosphonates
132
Q

anatomical factos that may affect implants

A
  • bone height
  • bone width
  • bone density or quality
  • proximity to inferior dental nerve proximity to maxillary sinus
  • tooth position
133
Q

what would you see in a clinically failed implant

A
  • moblity
  • pain
  • ongoing marginal bone loss
  • soft tissue infection
  • peri-implantatits
134
Q

constituents of dental amalgam

A
  • silver
  • tin
  • coppper
  • zinc
  • mercury
135
Q

what are the gamma, gamma 1 and gamma 2 phases in dental amalgam and what is there importance?

A

gamma phase is Ag3Sn

gamma 1 is Ag2Hg3

gamma 2 is Sn7Hg

gamma 2 is the weakest of the part of the amalgam - lowest tensile strength and is the softest of the phases

if the amount of gamma 2 phase can be limited in teh final dental amalgam the resulting amalgam will be strongth

136
Q

setting reaction for dental amalgam

A

Ag3Sn + Hg -> Ag3Sn + Ag2Hg3 + Sn7Hg

gamma + mercury -> gamma + gamma1 + gamma2

follwed by

gamma2 + AgCu -> Cu6Sn5 + gamma1

leaving no/little gamma2

137
Q

lathe cut particales

spherical particles

significance of different types

A

lathe cut alloy is made by chipping off pieces from a solid ingot of the alloy - results in particles of different shapes and sizes

spherical particles are made by melting the ingredients of the alloy together and spraying them into an inert atomosphere, droplets solidify into spherical pellets that are regular in shape and can be more closely packed together - amalgam needs less condensation force and results in increased strength of amalgam

138
Q

why is it common practice to overfill an amalgam cavity and carve it down

A

when amalgam is condensed the mercury rises to the surface of the restoration

to try and minimise the residual mercury left in the restoration it is usual to overfil the preparation and the excess mercury-rich amalgam can be carved away leaving the lower mercury containing amalgam which has greater strength and better longevity

139
Q

what are dental ceramics made of

A

feldspar, silica (quartz) and kaolin

140
Q

3 technical stages in making a porcelin jacket crown

A

first stage - compaction

  • powder is mixed with water and applied to the die so as to remove as musch water as possible and compact the material such that ther is a high density of particles, which minimises firing shrinkage

second stage - firing

  • crown is heated in a furnance to allow molten glass to flow between the powder particles and fill the voids

thrid stage - glazing

  • done to produce a smooth impervious outer layer
141
Q

adv and disadv of porcelain jacket crown

A

adv

  • excellent aesthetics
  • low thermal conductivity
  • high resistance to wear
  • glazed surface resists plaque accumulation

disadv

  • poor strength and very brittle, so often fracture
  • firing shrinkage so must be overbuilt
142
Q

how has poorn strength of porcelain jacket crowns been overcome

A

by fusing the porcelain to metal to produce metal ceramic restorations

by making reinforced ceramic core systems

creating resin bonded ceramics

143
Q

CADCAM stands for

A

computer assisted/aided design and computer assisted/aided manufacture

144
Q

requirements of metal ceramic alloy

A
  • high bond strength to ceramic
  • no adverse reaction with ceramic
  • melting temperature must be greater than the firing temperature of the ceramic
  • accurate fit
  • biocompatible
  • no corrosion
  • easy to use and cast
  • high elastic modulus
  • low cost
145
Q

dental cement uses

A
  • luting agents
  • cavity lining and bases
  • temporary restorations
146
Q

luting agents examples

A

modified zinc phosphate

zinc oxide adn eugenol

zinc polycarboxylate

glass ionomer

resin modified glass ionomer

compomers

resin cements

147
Q

cavity lining and bases examples

A

calcium hydroxide

zinc oxide and eugenol

148
Q

temporary restorations examples

A

zinc oxide and eugenol

glass ionomer

149
Q

which zinc based cement bonds to tooth substances

A

zinc polycarboxylate

150
Q

how to mix zinc polycarboxylate and why

A

on a glass slab as it must not be mixed on anything that absorbs water

addtitionally, glass slabs can be cooled and this will inc working time

151
Q

which cement cannot be used under composite restorations and why

A

zinc oxide and eugenol

eugenol is thought to interfere with teh proper setting of the composite material

152
Q

which material is used for pulp capping and why

A

calcium hydroxide is extremely alkaline pH11

helps with formation fo reparative dentine

also antibacterial and has a long duration of action

153
Q

which cement is thought to reduce sensitivity of a deep restoration

A

zinc oxide and eugenol

due to obtundent adn analgesic properties of eugenol

154
Q

indications for anterior veneers

A
  • discolouration of teeth
  • for closure of spaces/midline diastema
  • hypoplastic teeth
  • fracture of teeth
  • modifying the shape of a tooth
155
Q

maaterials used for veneers

A

porcelain

composite (direct/indirect)

156
Q

what would you need to check prior to advising placement of veneers

A
  • discoloration enough to warrant treatment or is it so severe that it will not be masked
  • pt smile line - helps determine which teeth need tx if for aesthetic reasons only, placement of cervical margin
  • is there enought crown present to support a veneer
  • any occlusal restrictions e.g. edge to edge occlusion, imbrication
  • any parafunctional activities
  • is there an alternative option e.g. balancing
157
Q

what is the thickness of veneers

A

0.5-0.7mm usually

158
Q

what is the long term prognosis of veneers

what to warn pt

A

may require replacement in the long term (e.g. approx 4 years for composite veneers) as a result of:

  • risk of chipping incisal edge
  • debonding
  • need to keep good gingival health
159
Q

key points during tooth prep for veneers

A
  • tooth reduction labially - depth cuts are helpful
  • chamfer finish line is helpful for the technician
  • margin - slightly supragingival unless discolouration, then margin can be subgingval
  • extend into embrasure but short of contact point
  • incisally either chamfer or wrap over onto palatal surface
160
Q

function of post and core

A

provides support and retention for the restoration and distributes streses along the root

161
Q

important to check this prior to placement of post and core

A

condition of the orthograde root filling and the apical condition as placement of the post will make it difficult to redo root canal filling so if necessary repeat orthograed root canal treatment

162
Q

ideal length of post

A

at least the length of the crown; approx 2/3 of the canal length

apical seal must not be distrubed so at least 4mm of the well condensed GP should be left

163
Q

classfication of post and core system:

A
  • prefabricated or custom made
  • parallel sided or tapered
  • threaded, smooth or serrated
164
Q

ideal characteristics of a post

A

post should have

  • adequate length
  • be as parallel as possible
  • have a roughened or serrated surface
  • not rotate in the root canal
165
Q

measure that can be taken to avoid post perforation

A

careful choice of post:

  • avoid large diameter post in small tapered roots, instead used tapered post and cement passively
  • avoid long post in curved roots
  • avoid threaded post which will inc internal stress within root canal
166
Q

how to manage a post perforation

A

depends on the location of perforation

  • if its in the coronal third try to incorporate into the design of the post crown e.g. diaphragm post and core preparation
  • for a minimal perforation in teh middle third - seal the perforation (e.g. lateral condensation) and reposition the post
  • in apical 2/3s - use a surgical approach to try to reduce the exposed post and seal the perforation

if attempting to repair the perforations, use of MTA is preferable

due to poor long term prognosis, extraaction may be favoured

167
Q

when are posterior crowns used

A
  • bridge abutments
  • restoring endodontically treated teeth
  • repairing tooth substances lost due to extensive caries/remaining tooth substance requires protection
  • fractured teeth
  • situations in which it is difficult to produce a reasonable occlusal form in a plastic material
168
Q

principles of posteiror crown prep

A
  • remove enough tooth substance to allow adequate thickness of material
  • develop adequate retention and resistance form
  • marginal intergrity, supragingival and onto sound tooth where possible
169
Q

tooth reduction needed for different materials for posterior crowns

A
  • full veneer gold crown - 1.5mm on functional cusp, 1mm elsewhere
  • porcelain fused to metal crown - same tooth reduction as for gold crown excepth where porcelain covereage is required where more tooth substance must be removed
  • occlusal reduction - metal occlusal surface requires same tooth reduction as for gold crown
  • all porcelain - occlusal surface 2mm supporting cussps and 1.5mm non suppporting cusps; buccal reduction 1.2-1.5mm; margins 1.2-1.5mm shoulder, if porcelain to tooth margin otherwise chamfer finish as for gold crown
170
Q

what features affect the retention and resistance form of the crown?

A

retention relies on

  • height, diameter and taper of the preparation
  • will also be increased by the placement of boxes, grove, pins and suface texturere

resistance relies on

  • taper or preparation, height to diameter ratio, correctly aligned and position grooves and boxes
171
Q

adv os partial covereage crown over full coverage crown

A
  • preservation of tooth structure
  • less pulpal damage
  • margins more likely to be supragingival
  • remaining tooth substance can act as a guide for technician
172
Q

21y.o. women presents with gingival recession affecting the lower incisors

how will you manage this

A

take a thorough history

  • CO:
    • present concerns, sensitivtiy
    • SOCRATES
  • HPC
  • DH
    • toothbrushing - frequency, duration
    • interdental
    • previous ortho tx or other tx
  • SH
  • MH

exam - inc asssessment of plaque, recession, probing depth, bleeding on probing, amount of attached gingivae, presence of functional gingivae, tooth mobility, vitality testing, occlusion

173
Q

recession is mild on all bar lower left lateral incisors in 21 y.o. female

how to proceed

A

taget traumatic tooth brushing and improve plaque control

monitor progression with clinical measurements, photos

treat sensitivity

take impression for study models

174
Q

causes of gingival recession

A
  • traumatic toothbrushing
  • incorrect toothbrushing technique
  • abrasive toothpaste
  • traumatic occlusion/incisor relationship
  • tooth out of arch
  • orhtodontic movement of tooth labially
  • habits such as rubbing of ginvivae with fingernail,pen etc
175
Q

gingival recession continues despite tx and prevention

what other options may be considered

A

mucogingival surgery to correct recession by a:

  • lataeral pedicle graft
  • double papilla flap
  • coronally repositioned flap
  • free gingival graft to provide a wider and functional zone of attached gingivae, taken from palate
  • thin acrylic gingival veneer/stent (rarely used)
176
Q

clinical features of necrotizing ulcerative gingivitis

A
  • painful yellowish white ulcer
  • inititally involve the interdental papillae
  • spread to involve the labial and lingual marginal gingivae
  • metallic taste
  • regional lymphadenopathy
  • fever
  • mallaise
  • poor oral hygiene
  • sensation of teeth biting wedged apart
177
Q

organisms implicated in nectosing ulcerative gingivitis

A

mixed picture

  • fuso-spirochaetal organisms (fusobacterium fusiformis)
  • gram negative anaerobes (pophymoonas, treponema, selenomasn, prevotella)
178
Q

risk factors for nectrotising ulcerative gingivitis

A
  • poor oral hygiene
  • pre-exisitng gingivitis
  • smoking
  • stress
  • malnourishment an debilitation
  • HIV infection
179
Q

tx nectorising ulcerative gingivtis

A
  • local measures
  • oral hygiene instructions
  • debridement
  • chemcial plaque control e.g. CHX
  • metronidazole 200-400mg three times daily for 3 days is systemically unwell
  • advice on management of risk factors, OHI, nutritional advice
180
Q

how can you classify periodontal disease (10)

A
  1. health
  2. plaque induced gingivitis (localised/generalised gingivitis)
  3. non plaque induced gingival disease and conditions
  4. periodontitis (localised, generalised, molar incisor)
  5. necrotising periodontal diseases
  6. periodontitis as a manifestation of systemic diseases
  7. systemic diseases or conditions affecting periodontal tissues
  8. periodontal abscesses
  9. periodontal-endodontic lesions
  10. mucogingival deformities and conditions
181
Q

juvenile periodontitis define

A

aggressive periodontitis occurring in an otherwise healthy adolescence characterised by rapid loss of connective tissue attachment and alveolar bone loss

usually localised to the incisors and first molars altough it can be generalised

182
Q

4 indicators for periodontal surgery

A
  • pockets greater than 6mm
  • pockets associated with thick fibrous gingivae
  • furction involvement
  • mucogingival deformitis or extensive periodontitis lesion requiring reconstruction or regenerative tx
  • short clinical crwn requiring inc in clincal crown height
  • gingival hyperplasia

SAQs for dentistry (5 decks)

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