Restorative

Question 1

what are the indications for crowns

Answer 1

improve aesthetics, improve OVD, improve occlusion and function, support reduced tooth tissue, support or retention for RPD or bridgework

Question 2

what are the contra-indications for crowns

Answer 2

extensive caries and periodontal disease, fracture, when more conservative options are available

Question 3

what are the principles of crown prep

Answer 3

preserve tooth tissue, structural durability, marginal integrity, preserve periodontal tissue, improve aesthetics

Question 4

what are the crown prep measurements for a metal only crown

Answer 4

axial - 0.5mm, functional cusp - 1.5mm, non-functional cusp - 0.5mm, margin - chamfer, 0.5mm

Question 5

what are the crown prep measurements for a metal ceramic crown

Answer 5

if metal only - 0.4mm, if ceramic as well - 0.9mm - 1.3mm

margin - 1.3mm or 0.5mm, chamfer non aesthetic, shoulder for aesthetic. functional cusp - 1.8mm

Question 6

what types of crowns are there

Answer 6

metal only - gold, metal ceramic crown - metal and porcelain, porcelain jacket - zirconia underneath supporting porcelain, porcelain only

Question 7

why do functional cusps need more prep

Answer 7

under more force, need more material so its stronger, thicker material - more prep

Question 8

name 3 types of preformed crowns

Answer 8

polycarbonate, clear plastic, stainless steel

Question 9

what are the disadvantages of preformed crowns

Answer 9

not an accurate fit, requires a large bank - costly

Question 10

why is a good provisional crown so crucial

Answer 10

if poor margins - not cleansible, cause inflammation and recession - definitive then wont fit, will also make it more difficult to take impressions

Question 11

what are indications of a successful provisional crown

Answer 11

good aesthetics, restore function - OVD, reduces sensitivity, easily cleansed - should be exposed to cleansible, margins at access for finish for dentist and clean for patient, above gingiva margin

Question 12

what are the indications for a veneer

Answer 12

improve aesthetics - shape, colour of teeth
correct peg shaped laterals
reduce or close proximal spaces
improve discolouration

Question 13

what are the contra-indications for veneers

Answer 13

if too extensive a prep is required - should be in enamel for mechanical retention
gingival recession
caries and perio disease

Question 14

what is the main failure for RCT

Answer 14

coronal microleakage - ingress of oral bacteria through coronal seal

Question 15

how do you decide what to restore RCT with

Answer 15

if marginal ridges intact - composite
if intact but discolouration - either composite and bleaching or crown/veneer
if broken down - crown

Question 16

when is a post-core used

Answer 16

for intra-radicular support when insufficient tooth tissue, gives retention and support for restoration

Question 17

what is the function of a post

Answer 17

retain and support core build up, extends from root canal

Question 18

what is the function of a core

Answer 18

retain and support restoration, what prosthesis is fixed to

Question 19

what is a post and core made of

Answer 19

post - metal, gold - ceramic, zirconia - fibre, glass

core - composite, amalgam, GI

Question 20

what is a ferrule

Answer 20

a dentinal collar, 1-2mm in vertical axis, circumferentially around cervical aspect of tooth. crown needs to bond on to tooth surface. if no ferrule, increased rate of fracture

Question 21

what are guidelines for post and core

Answer 21

should have ferrule, post should be tapered at 6 degrees, non-threaded and cemented, should be 3-5mm of GP left apically

Question 22

give 3 examples of post

Answer 22

smooth tapered, smooth parallel, threaded tapered, threaded parallel

Question 23

what structures are in the TMJ

Answer 23

cranial base - temporal
condyle head of mandible
articular disc - with superior and inferior articular space
mandibular fossa
articular eminence

Question 24

what are the movements at the TMJ

Answer 24

rotation, translation and lateral translation

Question 25

describe the rotation movement of TMJ

Answer 25

rotation of condylar head around an imaginary horizontal line - terminal hinge axis. movement fully within fossa, slight opening of 20mm, passive movement, clenching of teeth

Question 26

what is the facebow used for

Answer 26

to record the relationship of the maxilla with the terminal hinge axis

Question 27

what is posselts envelope

Answer 27

the border movements of the mandible in the sagittal plane

Question 28

what are the positions of posselts envelope

Answer 28

``` ICP - intercuspal position E - edge to edge P - protrusion T - maximum opening R - retruded axis position RCP - retruded contact position ```

Question 29

what is the mutually protected occlusion and why is it desired

Answer 29

canine guidance. desired as prevents excess lateral force on teeth caused by occlusion, unwanted tooth contacts can distort the teeth coming into ICP. no posterior teeth contacts - not subjected to lateral force

Question 30

what is used to record tooth contacts

Answer 30

miller forceps and articulating paper - 40 microns thick

Question 31

when do you record tooth contacts

Answer 31

before placing a restoration and before removing an old one - want to conform to occlusion after placing restoration or crown - ensure occlusion is not altered and no heavy contact on restorations

Question 32

what is static occlusion and how is it recorded

Answer 32

intercuspal position. lingual cusps of upper molars in contact with lower fossa, buccal cusps of lower molars in contact with upper fossa. recorded by tapping teeth together

Question 33

what are some deviations from ICP

Answer 33

``` incisor relationship class 2 div 1 - increased overjet div 2 - increased overbite anterior open bite posterior open bite cross bite ```

Question 34

what is dynamic occlusion

Answer 34

contacts during movement. lateral movement - working side and non-working side contacts. protrusive movement - posterior contacts

Question 35

what is the problem with posterior teeth contacts during lateral or protrusive movements

Answer 35

excessive lateral force which teeth are not able to withstand, musculature unable to rest as it should

Question 36

what would you be looking for when record dynamic occlusion

Answer 36

any marks on posterior teeth - slide marks, during lateral or protrusive movement

Question 37

what are some pathologies caused by unwanted tooth contacts

Answer 37

bruxism - eccentric or centric

Question 38

what is the anterior reference point

Answer 38

43mm apically to lateral incisor

Question 39

what different approaches can be used

Answer 39

conformative or reorganised

Question 40

what contact is used for designing a reorganised approach

Answer 40

first occlusal contact in Retruded arch of closure - RCP

Question 41

why might a reorganised approach be used

Answer 41

to increase OVD, when change in aesthetics is desired

Question 42

what is used to ensure casts are mounted accurately

Answer 42

facebow and intercuspal registration using either wax or paste

Question 43

what are the different types of discolouration

Answer 43

internal - fluorosis, tetracycline, nonvital tooth | external - tannins (coffee, tea, red wine), smoking, chromogenic bacteria

Question 44

explain how external bleaching works

Answer 44

hydrogen peroxide oxides high weight molecules to lower weight - less pigmentation

Question 45

what factors affect external bleaching

Answer 45

time, tooth surface, temperature, concentration

Question 46

compare at home bleaching with chairside

Answer 46

chairside - dentist in control, can ensure no damage to gingiva etc, however takes time and more expensive. faster results but dont last as long at home - patient needs good written instructions, trusting them, cheaper, takes longer for results but lasts longer, patient can keep guard in over night

Question 47

what are some disadvantages of external bleaching

Answer 47

sensitivity, relapse, tooth damage, gingival inflammation, problems with bonding

Question 48

describe internal bleaching

Answer 48

can only be done on non-vital teeth, gain access to pulp chamber, remove GP 1mm below ACJ, place RMGI, put hydrogen peroxide in, cotton wool and seal with RMGI. Remove in a day and do it weekly

Question 49

what are the requirements for internal bleaching

Answer 49

non-vital tooth, good RCT, no apical pathology

Question 50

what is external cervical resorption and how is it caused

Answer 50

odontoclasts breaking down dental hard tissue around cervical junction, caused by H2O2 diffusing through dentinal tubules to periodontal tissues

Question 51

how can internal and external bleaching be combined

Answer 51

can prepare tooth for internal, put bleach inside but also provide mouth guard and fill with bleach too, leave access cavity open with bleach in, patient has to keep this in 24 hours or will fill with food

Question 52

when is micro abrasion useful

Answer 52

for removal of discolouration caused by demineralisation, brown/yellow stain

Question 53

what are the legal requirements regarding bleachin

Answer 53

any hydrogen peroxide over 0.1% can only be sold or prescribed by dental professionals, anything over 6% cannot be sold unless requirement to prevent disease.