provisional EC restorations (3rd year) Flashcards
clinical stages for indirect restorations
preparation
temporisation
impressions and registration
cementation
when are they provided?
between the tooth prep and fit of an indirect restoration
what do they have a role in the immediate and long-term health of?
tooth
supporting structures e.g. PDL
definitive restoration
what characteristics should the provisional restore?
aesthetics function sensitivity coronal seal of RCT tooth destabilised occlusion
how should they fit?
good marginal fit
well-contoured - no overhangs
cleansable and maintainable by pt
consequences of a poorly fitting and contoured provisional
pt unable to clean - caries, gingival inflammation
poor moisture control
gingival overgrowth
uses of provisionals
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
ideal properties of provisional materials
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
types
custom formed - preferable - can be technically demanding preformed - standard shapes and sizes - adjust at chairside
custom resin provisional crowns material
chemically cured bis-acrylic composite resin (acrylic/composite hybrid)
e.g. Protemp Plus, Integrity Temp-Grip
custom resin provisional crowns fit advantages
fits tooth prep internally (inner surface hugs tooth prep)
reproduces contact points and occlusion externally
when should custom resin provisional crowns be made and why?
before impressions for definitive
check prep ok - undercuts, sufficient reduction
what can you use to check for sufficient prep reduction?
Svensen gauge
custom resin provisional crowns - what impression?
sectional - full arch unnecessary and difficult to reseat
custom resin provisional crowns - impression materials
addition cured silicone putty e.g. president
alginate
softened modelling wax
custom resin provisional crowns - addition cured silicone putty for impression pros and cons
can disinfect and keep - can be reused if pt loses provisional
resistant to tearing
custom resin provisional crowns - alginate for impression pros and cons
cheaper
cannot be reused/kept
custom resin provisional crowns - softened modelling wax pros and cons
easy to adjust and smooth cheap unsuitable for deep undercuts distorts cannot be reused
custom resin provisional crowns - alternative to impression
custom vacuum formed plastic mould (stent)
made on study model and/or diagnostic wax up
custom resin method
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
syringe bis-acrylic composite resin onto mixing pad - why?
ensure mixed
monitor setting
custom resin method - when remove set provisional what may happen?
stay on tooth - ease off with instrument beneath contact points, otherwise sets in undercuts
be removed in imp - leave to set
cementing custom resin crown
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
using provisionals for wear cases- establishing occlusion and aesthetics
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
using provisionals for wear cases - once guidance and aesthetics satisfactory
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
using provisionals for wear cases - guidance created on provisionals
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
using provisionals for wear cases - impressions of tooth preps (for definitives)
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
diagnostic wax up
satisfy pts aesthetic demands high aesthetic demand cases - alter provisionals - minor changes chairside - major - replace provisionals once satisfactory make impression for technician
establishing gingival contours
use provisionals to achieve satisfactory emergence profile for definitives
- illusion tooth comes out from gum
bone level dental implant
metal finishes at bone
used for anterior teeth - can mould gingiva
gingival level implant
ends at gingiva
easier to clean
used for posterior teeth
preformed provisional crowns variations
tooth coloured
- polycarbonate
- clear plastic crown forms filled with composite
metal - Al/SS
problems with preformed crowns
unlikely to fit accurately
large bank of crowns needed
when are preformed crowns useful?
situations where no impression taken prior to tooth prep or damage e.g. trauma cases
polycarbonate crowns
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
polycarbonate crowns method
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
what if polycarbonate crowns are overbuilt?
blanching of gingivae occurs
clear plastic crowns
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
metal preformed crowns
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
using old crown as provisional
if replacing, can use/modify original crown for temp
may need partially sectioned/relined
preserve original crown as much as possible
removing old crown
WAMkey
safe relax/ anthrogyr
sliding hammer
preformed malleable composite crowns
e.g. protemp crown temporisation material
soft - easily mouldable to tooth
preformed malleable composite crowns method
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
why is temporisation of veneers difficult?
relying on chemical retention rather than mechanical
temporisation for veneers
spot bonded, no etch
often don’t need temp as prep should be within enamel and pt can cope with aesthetics for short time
indirect provisionals
lab made (usually acrylic) low shrinkage IO more accurate high strength time and cost used long term examples of materials - composite, acrylic, meta
provisional replacement of missing teeth
conventional bridgework temporisation - diagnostic wax up of replacement
acrylic RPD
Essex retainer with pontic
edentulous space and only provisional crowns on prepared teeth
advice to pt
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
