Provisionals Part 1

Provisional Restorations

temp restoration meant to last for 2 weeks to a month

restores and maintains function to that area of the mouth and keeps the patient comfortable during the period from tooth preparation to final cementation

What material is commonly used for provisional restorations?

acrylic

What is the function/purpose of provisionals?

pulpal protection, positional stability, occlusal function, esthetics, diagnostic tool

What are the clinical requirements for provisionals?

occlusion, contacts, margins and contours, strength and retention, cost and ease of use, clinical efficiency

Why do provisionals need strength and retention?

to avoid fracture/dislodge

What is the order for analog impressions?

prep —> provisional —> impression

What is the order of digital impression?

prep —> digital impression —> provisional

What is the difference between analog and digital?

analog can physically be touched

When making a physical acrylic analog, what will produce the external tissue form? — 3 options

block carve

overimpression

preformed shells

Block Carve

a freehand method used to fabricate a temporary crown directly from a block or ball of acrylic resin

you put acrylic into patient's mouth

Overimpression

precise, negative imprints of your teeth and gums used to create exact 3D models

using alginate

Performed Shells

ready-made caps used to quickly protect a prepared tooth while a dental laboratory fabricates the permanent restoration

What produces the internal tissue form? — 2 options

direct intraoral reline

extraoral

What is the difference between the two?

direct = in patient's mouth

extraoral = you employ a model of prepared teeth

What materials can be used for provisionals?

acrylic

composite

Why is acrylic maybe not ideal for provisionals?

polymerization shrinkage

exothermic

What is a benefit of composite?

esthetic

What is a downside of composite?

brittle

Materials can be either ___ or ___

self-polymerizing

light cure

Picking between acrylic and composite may come down to what type of procedure you are working on... when would composite generally be better?

single units

How about acrylic?

bridges

Material of choice, between acrylic and composite, may also hinge upon ___ that is necessary

type of margin configuration

When should acrylics be used?

bevels

When should composites be used?

chamfer

shoulder

What is the more common provisional fabrication methodology?

combination of indirect/direct

Give the two combination possibilities:

- Custom shell or overimpression for external

form; use patient tissue for internal form

- **Preformed polycarbonate, clear acetate (strip-

off crowns) & metal crown forms used for

external form; patient tissue for internal form

Patient tissue form can be derived in internal and external fashions — explain each:

direct —> in mouth

indirect —> model was poured to resemble the mouth

Models can be made of ___ or ___

stone

plaster

or even silicone

How are shells created to obtain external surface form?

vacuform

Shells are often made of ___

clear acrylic

Overimpressions can be either ___ or ___

elastomeric

alginate

Elastomeric

material having elastic properties from rubber

Alginate

irreversible hydrocolloid material used for taking preliminary impressions

If you are using a tray, the putty inside is normally ___

medium body

If you are not using a tray, the putty inside is normally ___

heavy body

Preformed shells can be made of ___, ___, or ___

polycarbonate

clear acetate "strip off" crown formers

metal crown formers

Single Unit Anterior Provisional

temporary

can go in, can come out

for a single tooth

What is important for single unit anterior provisionals?

function

esthetics

Patients especially care about ___

esthetics

___ (technique) is discouraged for single unit anterior provisionals

Block carving

Why?

takes too much time

tedious

What can be utilized to help create single unit anterior provisionals?

preformed matrices

Preformed matrices include:

- Polycarbonate crown forms

- Clear acetate "strip off" crown forms

- Pre-op overimpression or vacuform shell

Clear strip off crown forms (do/do not) become part of the final provisional model

do not

Polycarbonate crown forms (do/do not) become part of the final provisional model

do

What are the gingival contours of clear strip offs/polycarbonates?

clear —> round

polycarbonate —> anatomic

Indirect technique is a better option for (single/multiple) units

multiple

Why not for single units?

it is a lot of work for one single unit

When selecting a correct crown former, you should measure ___ and ___ dimensions to help you select correct crown former from available selection

mesial/distal

occlusal/gingival

You should measure before trying polycarbonate crown in the mouth ... why?

this would potentially contaminate them for no reason, thus wasting the one's that don't fit

You need to modify ___ and ___ of the crown former as needed to optimize fit

gingival margin

internal surface

You may need to reline using ___

self-polymerizing resin

Reline

a procedure used to resurface the underside of a denture so it fits securely and comfortably against your gums

Can reline acrylics additionally be used to adjust shade of crown?

yes

You want to remove relining resin when it becomes ___

doughy/a bit hot

Why?

you don't want it to lock on

still need to edit it

If relining composite provisionals, what must you first do to the tooth surface?

roughen it up

add a bit of bonding agent

Does relining involve adding extra composite?

Yes. In dentistry, reline procedures generally involve etching the existing composite, applying a bonding agent, and adding a fresh layer of composite (often a lower-viscosity "flowable" composite).

Is roughening the surface and adding bonding agent necessary for acrylic relines?

no

Relines capture ___ and ___ form

margin

internal

When working on a reline, to finish it up, you ___ and ___

trim excess

reseat

To correct a reline, you may need to move ___

line angles

To correct a reline, you may need to add ___

acrylic to close any open margin

Correcting open margins is a lot of work... to prevent thus issue, it is important to initially ___

choose a crown former that covers the entire finish line

You hypothetically want to avoid "___" adding acrylic after the fact, if you can

paint-on

When adjusting occlusion of provisionals, you want to reduce ___

centric bullseyes

You also want to ensure that ___ is good when analyzing occlusion

protrusive

T/F: you want protrusive contact on all anterior teeth, if possible

true

Do you finish & polish provisionals, at the end?

yes

What fit is more important, at the beginning: at incisal or at gingival margin?

gingival margin

Crown formers are filled with ___ before being placed into the mouth

acrylic/composite

If you have very little tooth structure remaining and want to create a provisional, you may need to insert a ___

post

Why do you need a post?

previous methods won't work without it due to lack/loss of resistance and retention

If a patient with a lot of tooth structure missing wants a same day solution, we use ...

post

acrylic

polycarb crown

What is the name of the lab-fabricated method that takes a few days to produce a provisional?

cast post and core

Teeth with a lot of tooth structure missing have usually been treated ___

endodontically

Let's go back to selection of crown forms... you should use ___ for size measurement

calipers

When applying a crown form, you mark the ___ and adjust using ___

gingival outline

scissors

Along with cutting the crown former to fix the gingival margin, you can also modify its ___ if necessary

contours

What instrument do you use to bend/contour?

pliers

When using clear strip-off crowns, use ___ to release trapped air

vent holes

After trimming, you then proceed to the ___ stage

try-in

Clear crown formers work well for restoration of ___

large composite restorations on anterior teeth

Why do you use clear formers?

able to cure through it

You must remove the clear shell. This may leave a problem:

open contacts

Why?

due to thickness of the clear shell.. it needs to be closed, eventually

Metal crown formers are more commonly used for ___ teeth when you keep them in as part of the final provisional

posterior

Why?

esthetic purposes

Metal crown formers are mostly used in ___ when keeping them in

pediatrics

What metals can be incorporated?

aluminum

tin-silver

nickel-chromium

You can smoothen the edges of a provisional using a ___

stone

When setting a provisional, look for ___... this indicates a not ideal placement

gingival blanching

Gingival blanching is a sign of ___ and/or ___

overextended margins

bulky contours

If you are using a metal crown former filled with acrylic and do NOT want to have a metal provisional, what do you do?

remove the metal! after the acrylic appropriately sets

After placing a provisional, you have the option to modify potential errors by ___

painting on short/open margins

You do not want ___ on inner inclines when putting provisionals in

interferences

If you have a tooth with a missing portion, there are three methods to create a provisional:

1) indirect and straight into the mouth — mostly digital

2) use a model that you measure and think has proper dimensions, fill it with material, and place it in... take it in and out while modifying it.. then eventually seat it

3) put a piece that fits in, get the dimensions of the whole 'fixed' tooth structure, mold this whole into a provisional

Explain 2 more simply:

guess and adapt

Explain 3 more simply:

pre adapt and use what you have

Explain 1 more simply:

use a digital scan to see something that you know will fit ahead of time