provisional EC restorations (3rd year)

Question 1

clinical stages for indirect restorations

Answer 1

preparation
temporisation
impressions and registration
cementation

Question 2

when are they provided?

Answer 2

between the tooth prep and fit of an indirect restoration

Question 3

what do they have a role in the immediate and long-term health of?

Answer 3

tooth
supporting structures e.g. PDL
definitive restoration

Question 4

what characteristics should the provisional restore?

Answer 4

aesthetics
function
sensitivity
coronal seal of RCT tooth
destabilised occlusion

Question 5

how should they fit?

Answer 5

good marginal fit
well-contoured - no overhangs
cleansable and maintainable by pt

Question 6

consequences of a poorly fitting and contoured provisional

Answer 6

pt unable to clean - caries, gingival inflammation
poor moisture control
gingival overgrowth

Question 7

uses of provisionals

Answer 7

establish/maintain aesthetics
prevent sensitivity
cleansable
maintain gingival health and contour
prevent micro leakage - preserve vitality
confirm adequate prep
IC and EC design characteristics - occlusal stability
 - no OVD changes (unless required)
 - prevent drifting/tilting of prepared teeth
preseve/improve fct
 - mastication/speech
isolation for RCT
matrix for core build-up

Question 8

ideal properties of provisional materials

Answer 8

non-irritant
low temp rise during setting
 - high will cause expansion
dimensionally stable
adequate working and setting time
adequate strength and wear resistance
 - if too strong hard to remove
good aesthetics

Question 9

types

Answer 9

custom formed
 - preferable
 - can be technically demanding
preformed
 - standard shapes and sizes
 - adjust at chairside

Question 10

custom resin provisional crowns material

Answer 10

chemically cured bis-acrylic composite resin (acrylic/composite hybrid)
e.g. Protemp Plus, Integrity Temp-Grip

Question 11

custom resin provisional crowns fit advantages

Answer 11

fits tooth prep internally (inner surface hugs tooth prep)

reproduces contact points and occlusion externally

Question 12

when should custom resin provisional crowns be made and why?

Answer 12

before impressions for definitive

check prep ok - undercuts, sufficient reduction

Question 13

what can you use to check for sufficient prep reduction?

Answer 13

Svensen gauge

Question 14

custom resin provisional crowns - what impression?

Answer 14

sectional - full arch unnecessary and difficult to reseat

Question 15

custom resin provisional crowns - impression materials

Answer 15

addition cured silicone putty e.g. president
alginate
softened modelling wax

Question 16

custom resin provisional crowns - addition cured silicone putty for impression pros and cons

Answer 16

can disinfect and keep - can be reused if pt loses provisional
resistant to tearing

Question 17

custom resin provisional crowns - alginate for impression pros and cons

Answer 17

cheaper

cannot be reused/kept

Question 18

custom resin provisional crowns - softened modelling wax pros and cons

Answer 18

easy to adjust and smooth
cheap
unsuitable for deep undercuts 
distorts
cannot be reused

Question 19

custom resin provisional crowns - alternative to impression

Answer 19

custom vacuum formed plastic mould (stent)

made on study model and/or diagnostic wax up

Question 20

custom resin method

Answer 20

sectional impression
prep tooth
syringe bis-acrylic composite resin onto mixing pad
syringe into sectional
relocate impression in mouth
- fully seated
- click over bulbosity of remaining tooth
remove before complete polymerisation (about 1.5mins)
- rubbery
- fully polymerised hard to remove from undercuts
remove completely
remove flash and ledges - high speed/soft flex discs
confirm tooth prep - Svensen gauge
check marginal fit and occlusion in situ - adjust if required (ideally outside mouth)
check aesthetics
cement

Question 21

syringe bis-acrylic composite resin onto mixing pad - why?

Answer 21

ensure mixed

monitor setting

Question 22

custom resin method - when remove set provisional what may happen?

Answer 22

stay on tooth - ease off with instrument beneath contact points, otherwise sets in undercuts
be removed in imp - leave to set

Question 23

cementing custom resin crown

Answer 23

temp luting cement e.g. TempBond NE - non-eugenol temp cement material
trim away excess - let it set then you can just peel excess off
- margins
- interdentally - floss

Question 24

using provisionals for wear cases- establishing occlusion and aesthetics

Answer 24

loss of original tooth form e.g. wear
 - reestablish tooth shape
 - pilot occlusion and aesthetics using provisionals
guidance (anterior/incisal)
 - produce on crowns
 - diagnostic wax up, study models
 - require Facebow

Question 25

using provisionals for wear cases - once guidance and aesthetics satisfactory

Answer 25

lab - duplicate waxed-up cast, construct vacuum formed stent next pt visit - prepare teeth, use mould to produce custom formed provisional restoration to new occlusion and appearance pt trial - wear until happy with form and fct - adjust/alter - trim with bur, add composite

Question 26

using provisionals for wear cases - guidance created on provisionals

Answer 26

can be transferred to definitives custom formed incisal guidance table - imps of provisionals in situ and opposing teeth - mount casts on semi-adjustable - unset acrylic on incisal table - reproduce lateral and protrusive movements - light cure and give to lab - custom incisal guidance table - copy of occlusal scheme that you want followed when constructing restoration

Question 27

using provisionals for wear cases - impressions of tooth preps (for definitives)

Answer 27

master cast mounted on articulator technician constructs definitives - guided by custom-formed incisal table - simultaneous contact between restorations/opposing teeth and incisal pin/guidance table

Question 28

diagnostic wax up

Answer 28

``` satisfy pts aesthetic demands high aesthetic demand cases - alter provisionals - minor changes chairside - major - replace provisionals once satisfactory make impression for technician ```

Question 29

establishing gingival contours

Answer 29

use provisionals to achieve satisfactory emergence profile for definitives - illusion tooth comes out from gum

Question 30

bone level dental implant

Answer 30

metal finishes at bone | used for anterior teeth - can mould gingiva

Question 31

gingival level implant

Answer 31

ends at gingiva easier to clean used for posterior teeth

Question 32

preformed provisional crowns variations

Answer 32

tooth coloured - polycarbonate - clear plastic crown forms filled with composite metal - Al/SS

Question 33

problems with preformed crowns

Answer 33

unlikely to fit accurately | large bank of crowns needed

Question 34

when are preformed crowns useful?

Answer 34

situations where no impression taken prior to tooth prep or damage e.g. trauma cases

Question 35

polycarbonate crowns

Answer 35

tooth coloured shells don't really fit round tooth - fill inner surface with acrylic tooth morphology - anteriors and premolars - sublined with acrylic e.g. trim

Question 36

polycarbonate crowns method

Answer 36

``` select shell slightly larger than prep trim back until - correct prep dimension - sits fully over tooth prep - not bedding into gingivae - pink stone in straight handpiece fill shell - trim/protemp seat over tooth allow polymerisation remove check fit trim if necessary cement with temp luting cement cut off tag ```

Question 37

what if polycarbonate crowns are overbuilt?

Answer 37

blanching of gingivae occurs

Question 38

clear plastic crowns

Answer 38

``` select and trim until fit - scissors pierce hole at cusp tip/canine tip/incisal angle so air can escape - no bubbles fill with bis-acrylic composite resin seat over tooth allow setting remove from tooth remove plastic crown form check margins and occlusion - adjust cement with temp cement ```

Question 39

metal preformed crowns

Answer 39

used for posterior teeth Al or SS any ledges/sharp margins - soft tissue trauma difficult to adjust - some provided with crimping device to help mould margins

Question 40

using old crown as provisional

Answer 40

if replacing, can use/modify original crown for temp may need partially sectioned/relined preserve original crown as much as possible

Question 41

removing old crown

Answer 41

WAMkey safe relax/ anthrogyr sliding hammer

Question 42

preformed malleable composite crowns

Answer 42

e.g. protemp crown temporisation material | soft - easily mouldable to tooth

Question 43

preformed malleable composite crowns method

Answer 43

moulded over tooth to desired shape partially light cured 2-3s, otherwise difficult to remove remove then cure completely outside of mouth check fit adjust if necessary cement

Question 44

why is temporisation of veneers difficult?

Answer 44

relying on chemical retention rather than mechanical

Question 45

temporisation for veneers

Answer 45

spot bonded, no etch | often don't need temp as prep should be within enamel and pt can cope with aesthetics for short time

Question 46

indirect provisionals

Answer 46

``` lab made (usually acrylic) low shrinkage IO more accurate high strength time and cost used long term examples of materials - composite, acrylic, meta ```

Question 47

provisional replacement of missing teeth

Answer 47

conventional bridgework temporisation - diagnostic wax up of replacement acrylic RPD Essex retainer with pontic edentulous space and only provisional crowns on prepared teeth

Question 48

advice to pt

Answer 48

pt to maintain good OH - caution with floss as may pull out provisional otherwise gingival inflammation - GCF - bleeding - poor moisture control for definitive imps inadequate cement lute placement