deptt of prosthodontics crown and bridge

PROVISIONAL RESTORATIONS IN FIXED PARTIAL DENTURES

SEMINAR

DR VIKAS AGGARWAL

INDEX

1. INTRODUCTION

2. DEFINITION

3. RATIONALE FOR PROVISIONAL TREATMENTS

4. FUNCTIONS OF PROVISIONALS

5. REQUIRMENTS OF PROVISIONAL RESTORATIONS

6. MATERIALS

7. INFLUENCE OF MATERIAL PROPERTIES ON TREATMENT

OUTCOME

8. FABRICATION OF PROVISIONAL RESTORATIONS

9. TECHNIQUES OF MAKING PROVISIONAL RESTORATIONS

10.CUSTOM SINGLE UNIT PROVISIONAL RESTORATIONS

11.PREFABRICATED PROVISIONAL RESTORATIONS

12.CEMENTATION

13.REMOVAL, RECEMENTATION AND REPAIR

14.CONCLUSION

15.REFERENCES

INTRODUCTION

It is important that the prepared tooth be protected and that patient be kept

comfortable while a cast restoration is being fabricated. By successful

management of this phase of the treatment, the dentist can gain the patients

confidence and favourable influence for the ultimate success of the final

restoration. The important role of provisional restorations is often overlooked as

they generally do not need to last for long. However, not only can good

provisional restorations help produce better final restorations, they can also save

a lot of time

Failure to do so will result in the eventual loss of more time than initially

thought saved. If the provisional restoration is not up to the mark, it may lead to

unnecessary repairs as well as need to treat gingival inflammation and it can

further prolong the treatment schedule. Whatever the intended length of time of

treatment, a provisional will have to be adequate to maintain patient health.

Thus it should not be casually fabricated on the basis of expected short term

use.

It can be said that provisional restoration is frequently the patient’s first

impression of final prosthesis so it should be representative of the final esthetic

result.

During the time between the preparation of the tooth and the placement of the

final restoration, the tooth is protected by a provisional restoration. This type of

restoration has also been known for many years as a temporary restoration.

The word provisional means established for the time being, pending a

permanent arrangement.

DEFINITION (ACC TO GPT-8)

Fixed or removal prosthesis designed to enhance esthetics, stabilization and or

function for a limited period of time, after which it is to be replaced by

definitive prosthesis. Often such prosthesis is used to assist in determination of

the therapeutic effectiveness of a specific treatment plan or the form of function

of the planned definitive prosthesis.

Rationale for Provisional Treatment (JPD 2003, 90, 474-497)

Protect pulpal tissue and sedate prepared abutments

Protect teeth from dental caries

Provide comfort and function

Evaluate parallelism of abutments

Provide method for immediately replacing missing teeth

Prevent migration of abutments

Improve esthetics

Provide an environment conductive to periodontal health

Evaluate and reinforce the patient’s oral home care

Assist with periodontal therapy by providing visibility and access to

surgical sites when removed

Provide a matrix for the retention of periodontal surgical dressings

Stabilize mobile teeth during periodontal therapy and evaluation

Provide anchorage for orthodontic brackets during tooth movement

Aid in developing and evaluating an occlusal scheme before definitive

treatment

Allow evaluation of vertical dimension, phonetics, and masticatory

function

Assist in determining the prognosis of questionable abutments during

prosthodontic treatment planning

FUNCTIONS OF PROVISIONAL RESTORATIONS

1) Comfort/tooth vitality: To cover exposed dentine to prevent sensitivity,

plaque builds up, subsequent caries and pulp pathology.

2) Occlusion and positional stability: To prevent unwanted tooth movement

by the maintenance of intercuspal and proximal contacts. It may be necessary to

establish a holding contact on the provisional restoration. Depending on the

patient’s occlusal scheme, the provisional restoration may need to provide

guidance in protrusive and lateral excursions, or disocclude to prevent working

or non working interferences. Interproximal contacts also need to be maintained

to prevent food packing.

3) Function it restores patients functions

4) Gingival health and contour: To facilitate oral hygiene and prevent gingival

overgrowth provisional restorations require accurate margins and cleansable

contours. They can be used in the interim where the level of the gingival margin

has yet to stabilise (e.g. after crown lengthening or removal of a crown with

defective margins).

5) Aesthetics: To provide an adequate interim appearance provisional

restoration should either mimic the tooth just prepared, or the final intended

restoration.

6) Diagnosis: If any change in the esthetics or occlusion is required, the

provisional restoration is your trial run. Changes are easily made in the

temporary stage. Once final contours are obtained, the temporary can be

duplicated and sent to the laboratory as a guide for construction of the final

restoration

Provisional restoration can be very useful in diagnosis for the following factors:

Establishment of occlusal plane

Determining path of insertion

Evaluation of pontic design

Evaluation of patient’s esthetic demands

Evaluation of patient’s phonetics

7) Other practical uses: To measure tooth reduction, to isolate during

endodontics, to assess prognosis, to act as a matrix for core construction

REQUIREMENTS OF PROVISIONAL RESTORATION

There are three basic requirements that is biological, mechanical and esthetics.

There should be optimal balance between these factors for the success of any

restoration.

A) BIOLOGICAL REQUIREMENTS

1) PULPAL PROTECTION

It must seal and insulate the prepared tooth surface from oral environment, to

prevent sensitivity and further irritation to pulp. Tooth has already been

traumatized to certain extent during tooth preparation; if provisional restoration

does not seal the tooth properly it can lead to irreversible pulpitis.

2) PERIODONTAL HEALTH

BIOLOGICALProtect pulp

Maintain periodontalhealth

Provide occlusalcompatibility

Maintain tooth positionProtect against fracture

MECHENICALResist functional loadsResist removal forces

Maintain interabutment

alignment

ESTHETICS Easily contourable

Colour compatibilityTranslucency

Colour stability

To facilitate plaque removal, an interim fixed restoration must have good

marginal fit, proper contour, and a smooth surface. This is particularly

important when the crown margin is placed apical to the free gingival margin. If

the interim fixed restoration is inadequate and plaque control is impaired,

gingival health deteriorates. It will lead to delay in placement of final prosthesis.

3) OCCLUSAL COMPATIBILITY AND TOOTH POSITION

It should establish proper contact with adjacent and opposing teeth. It will

prevent supraeruption and horizontal movement of prepared tooth. Any such

movement will require adjustments or a remake of the final restoration at the

time of cementation.

4) PREVENTION OF ENAMEL FRACTURE

The interim fixed restoration should protect teeth weakened by crown

preparation, particularly true with partial coverage designs in which the margin

of the preparation is close to the occlusal surface of the tooth and could be

damaged during chewing. Even a small chip of enamel makes the definitive

restoration unsatisfactory and necessitates a time-consuming remake

B) MECHANICAL REQUIREMENTS

1) FUNCTION

Greatest stresses on interim fixed restorations are likely to occur during

chewing. The strength of temporary prosthesis is increased by increasing the

size of connectors in comparison with definitive restorations. Greater strength is

achieved by reducing the depth and sharpness of the embrasures. This increases

the cross-sectional area of the connector while reducing the stress concentration

associated with sharp internal line angles.

The biologic and sometimes the esthetic requirements place limits on just how

much larger connectors can be made. To avoid jeopardizing periodontal health,

they should not be overcontoured near the gingiva.

2) DISPLACEMENT

Interim restoration should avoid displacement that is best prevented by proper

tooth preparation and well adapted internal surface.

3) REMOVAL FOR REUSE

Interim restorations often need to be reused and so should not be damaged when

removed from the teeth. In most instances, if the cement is sufficiently weak

and the interim restoration has been well fabricated, it does not break upon

removal.

C) ESTHETIC REQUIREMENT

The appearance of an interim fixed restoration is particularly important for

incisors, canines, and sometimes premolars. The temporary must have adequate

contours, colour, translucency and texture. The provisional can be a "testing

ground" for esthetic changes such as tooth shape, length or colour. The

temporary can be easily altered until the patient is satisfied with the esthetics.

Cosmetic modification should be made with input from the patient and used as a

guide for the fabrication of the final prosthesis.

To summarize: (JPD 2003, 90, 474-97)

Good marginal adaptation; adapts well to a tooth and matrix surface

Adequate retention and resistance to dislodgment during normal

masticatory function

Strong, durable, and hard

Nonirritating to pulp and other tissues; low exothermicity

Nonporous and dimensionally stable

Comfortable

Esthetically acceptable shade selection; translucent tooth-like appearance

Colour stable

Physiologic contours and embrasures

Easy to mix and load in the matrix, fabricate, reline, and repair; relatively

short setting time

Physiologic occlusion

Conductive to routine oral home-care cleaning procedures

Finishes to a highly polished, plaque- and stain-resistant surface

Easy to remove and re-cement by the dentist

Relatively inexpensive

Low incidence of localized allergic reactions

PROVISIONAL RESTORATIVE MATERIALS:

Ideal properties:

1. Convenient handling.

2. Biocompatibility.

3. Dimensional stability during solidification.

4. Ease of contouring and polishing.

5. Adequate strength and abrasion resistance.

6. Good appearance.

7. Good patient acceptance.

8. Ease of adding to or repairing.

9. Chemical compatibility with provisional luting cements

Provisional materials can be classified as:

A) Custom fabricated materials.

B) Preformed materials

CUSTOM FABRICATED MATERIALS.

These are one of the best choices for provisional restorative treatment. The

technique allows for intimate contact between a provisional restoration and

prepared tooth. It provides a continuous mechanism for a variety of alterations

during treatment such as marginal adaptation, contour change, shade

adjustment, occlusal modification and repair.

These materials can be divided based on their mode of polymerization

1. chemically activated autopolymerizing acrylic resins

2. heat activated acrylic resins;

3. light-activated acrylic resins

4. “dual” light and chemically activated acrylic resins

Acrylic resins are most common choice of provisional restorative material.

Generally, acrylic resins used for provisional restorations are brittle, but their

great advantage is the ease with which they can be altered by additions and

subtractions. Several types of acrylic resin materials are available for interim

restorative treatment.

(1) Polymethyl methacrylate resins

(2) Polyethyl methacrylate resins

(3) Bis GMA composite

(4) Visible light cure resin

Poly methyl methacrylate.

Autopolymerizing polymethyl methacrylate (PMMA) first appeared around

1940 and remains the most frequently used material for fabrication of interim

restorations

Advantages

Low cost

Good wear resistance

Good esthetics and colour stability

Capable of high polish

Good marginal finish

Disadvantages

Significant amount of heat given off by exothermic reaction

High degree of shrinkage (about 8%)

Strong, objectionable odour

Short working time

Hard to repair.

monomer irritating to pulp

eugenol deteriorates resin

Products: Coldpac, Duralay, Jet,Temporary bridge resin., Trim Plus etc.

Poly-ethyl Methacrylates

Ethyl methacrylate was introduced in the 1960s, has a number of advantages

and disadvantages relative to methyl methacrylate. One study, showed the

highest value of fracture resistance with an ethyl methacrylate material relative

to methyl methacrylate and bis-acryl materials. Ethyl methacrylate may be a

better selection for direct interim prosthesis fabrication and is best suited for

short-term use relative to methyl methacrylate.

Advantages:

Lower exothermic heat.

Low polymerization shrinkage.

Good handling properties.

Good polishability.

Less pungent odor

Good toughness

.

Disadvantages:

Low tensile strength.

Poor surface hardness.

Poor wear resistance.

Poor durability.

Poor colour stability

Products: Splintline

COMPOSITES

Composite provisional materials are chemically comprised of a combination of

2 or more types of material. Most of these materials use bis-acryl resin, a

hydrophobic material that is similar to bis-GMA. When this resin is mixed with

inorganic, radiopaque filler it combines to provide an interim treatment material

that is similar to composite restorative materials. Typically these materials use a

variety of multifunctional acrylic resin monomers that produce high-density

cross linkages during polymerization.

These materials are available as

• Autopolymerized.

• Dual polymerized.

• Visible light polymerized.

Advantages

Less shrinkage than acrylics

Minimal heat generated during setting reaction

Relatively high strength

Minimal odour

Excellent esthetics

Most products use automix delivery

Can be repaired or characterized using resin composite

Easy to trim

Disadvantages

Poor surface hardness

Expensive

Brittle

Alterations and repairs are difficult

Poor stain resistance

Less polishability

Poor handling characteristics

Poor colour stability

Products: Protemp Garant,

VISIBLE LIGHT CURE RESIN / UDMA BASED

The visible light polymerized (VLC) materials, first introduced in the 1980s,

require the addition of urethane dimethacrylate, a resin whose polymerization is

catalysed with visible light energy and a camphoroquinone/ amine photo

initiator. These materials usually incorporate a filler such as microfine silica to

improve physical properties such as reduced polymerization shrinkage. Unlike

methacrylate resins, they do not produce residual free monomers after

polymerization, which explains why they exhibit significantly decreased tissue

toxicity relative to methacrylate resins. Eg Triad.

ADVANTAGES

Controlled working time

Good surface hardness and wear resistance

Good transverse strength

Low temperature change

Good colour stability

DISADVANTAGES

Poor marginal fit

Poor stain resistance

Limited shade availability

Expensive

PREFORMED MATERIALS

Various types of preformed crowns are available from several manufacturers.

Such products find greatest use for protection of individual teeth that are being

restored and need protection for only a short period of time

Polycarbonate Crowns:

They are most natural appearance of all the preformed materials. Very colour

stable resin. Colour can be modified by shade of the lining resin

These are available for incisors, canines and bicuspids. There is a range of sizes

for each tooth form. They are highly esthetic and should be relined with acrylic

in order to provide a good internal fit. After lining with acrylic, they may be

trimmed to provide a good marginal adaptation and further adjusted into proper

occlusion.

Cellulose acetate

These are shells made of cellulose acetate (0.2m to 0.3 mm) and are available in

all tooth forms. These shells come in various sizes for each tooth form and are

lined with acrylic resin. After the acrylic resin has polymerized, the cellulose

shell is peeled away from the crown. This usually necessitated the further

addition of acrylic in the areas of the proximal contacts.

Aluminum and Tin Silver:

They are suitable for posterior teeth. They are available in anatomic an form,

which has elaborated occlusal and axial surfaces. Non-anatomic forms are least

expensive and they have to be modified to suitable occlusal surfaces. Care must

be taken to avoid fracturing the delicate cavo surface margin of the tooth

preparation when fitting a metal crown. The risk is greater if the cervical

contours are constricted and if the patient is asked to bite directly on it for

adaptation. Direct stretching on the tooth should be done only if the preparation

has featheredge margins or else cervical enlargement has to be done on swaging

block, which are supplied with the crown kit.

NICKEL -CHROMIUM

They are used in children primarily with extensively damaged primary teeth.

Nickel-chromium usually is not lined instead; they are contoured with pliers and

are luted with high strength cements. They are hard and can be used for long-

term provisional restorations.

INFLUENCE OF MATERIAL PROPERTIES ON TREATMENT

OUTCOME (JPD 2003, 90, 474-497)

1) Marginal accuracy

Accurate marginal adaptation of resinous provisional restorations to the finish

line of a prepared tooth assists in protecting the pulp from thermal, bacterial,

and chemical insults. The accuracy could be significantly improved by relining

the restoration after the initial polymerization.

A number of studies have focused on the marginal accuracy of provisional

crown.

(1) Crispin etal 1980 evaluated marginal accuracy with direct and indirect

techniques. They reported that indirect fabrication provided significant

improvements in marginal fit relative to direct techniques

(2) Improved marginal accuracy of PMMA provisional restorations occurred

when a shoulder finish line was used compared with a chamfer marginal design.

(Hung et al 1993)

(3) Light-polymerized materials provided significantly improved marginal

accuracy relative to auto polymerizing PMMA resin after thermocycling.

(Dubious et al 1999)

(4) Nearly 20% improvement in the retention of interim crowns made with

polymethyl methacrylate compared to those fabricated with composite

materials. It was concluded that polymerization shrinkage occurring with the

polymethyl methacrylate material might have allowed for a tighter fit of the

restoration on the prepared tooth, which had a direct influence on improved

retentive quality. (Lepe et al 1999)

(5). Acrylic resin provisional crowns demonstrated dimensional degeneration

and enlarged marginal gaps resulting from thermocycling and occlusal loading.

(Ehernberg and Weiner 2000)

2) COLOUR STABILITY

In esthetically critical areas it is desirable for provisional restoration to remain

colour stable over the course of provisional treatment. Discolouration of

provisional materials can produce serious esthetic complications, especially

when long term provisional treatment is required. Modern provisional materials

use stabilizers that decrease chemically induced colour changes, but these

materials are susceptible to other factors that will promote staining. Most

provisional materials are subject to sorption, a process of absorption and

adsorption of liquids that occurs relative to environmental conditions. When

provisional materials contact pigmented solutions such as coffee or tea,

discolouration is possible. Porosity and surface quality of provisional

restorations as well as oral hygiene habits can also influence colour changes.

1) Crispin and Caputo (1979) studied the colour stability of provisional

materials. They found that methyl methacrylate materials exhibited the least

darkening, followed by ethyl methacrylate and vinyl-ethyl methacrylate

materials.

2) Yannikakis et al (1998) immersed provisional materials in various staining

solutions for up to 1 month. They reported that all materials showed perceptible

colour changes after 1 week. The methyl methacrylate materials exhibited the

best colour stability and bis-acryl materials the worst.

3) GINGIVAL RESPONSE

Inflammation and recession of the free gingival margin associated with

provisional treatment is a common occurrence

Donaldson 1973 indicated that the occurrence of gingival recession before

provisional treatment was directly linked to further recession observed after the

completion of definitive prosthodontic treatment. He also found a direct relation

between the degree of pressure applied by a provisional restoration and gingival

recession. An anatomically contoured provisional restoration caused less

recession than did a nonanatomically contoured one. Periodontal inflammation

associated with provisional treatment could be expected to be a reversible

process provided that the amount of gingival irritation is minimal and

provisional treatment occurs over a short time span.

MacEntee etal 1978 in histological evaluation of tissue response reported no

detectable change in gingival tissue associated with provisional restorative

treatment over 3 weeks period.

Garvin et al 1982 concluded that periodontal inflammation associated with

provisional treatment could be expected to be a reversible process provided that

the amount of gingival irritation is minimal and provisional treatment occurs

over a short time span.

4) PULPAL RESPONSE

Dental pulp inflammation can be caused by either thermal or chemical insult

resulting from materials used to produce direct provisional restorations.

Temperature rise of more than 5.6°C are considered unacceptable because of a

potential for loss of pulp vitality and this should be considered when fabricating

direct provisional restorations. The amount of heat generated is directly

proportional to the amount of material used. Hence temperature will be high

when using multiple units. Use of air and water coolants, as well as by use of a

matrix material, can dissipate heat rapidly and the pulp temperature rise might

be reduced.

Grajower et al.1979 showed faster polymerizing acrylic resin materials could

generate higher temperatures than slower polymerizing resins.

The authors concluded that

(1) Provisional acrylic resin restorations might be fully polymerized on prepared

teeth by appropriate methods such as in impressions or with external cooling,

without causing excessive heating of the dental pulp

(2) Removal of a provisional restoration before complete polymerization,

leading to potential deformation of the acrylic resin material, is therefore

unnecessary

(3) A thin insulating layer should be applied to a prepared tooth before contact

with nonpolymerized acrylic resin to avoid chemical injury.

4) HYPERSENSITIVITY

Hypersensitivity from provisional materials has been reported but appears to be

rare. Autopolymerizing methacrylate materials have greater potential for

producing allergic contact stomatitis than similar heat-polymerized materials.

The residual monomer in the material has been implicated as the causative

factor. Indirect material processing methods are recommended for individuals

showing evidence of hypersensitivity.

Residual monomer content in heat polymerized acrylic resin ranges from

0.045%-0.103%, whereas in autopolymerizing acrylic resins it is 0.185%.

Unpolymerized monomer can be substantially removed by placing auto

polymerized provisional restoration in a pressure pot with warm water for 20

mins.

FABRICATION OF PROVISIONAL RESTORATION

Many procedures using a wide variety of materials are available to make

satisfactory provisional restorations. Common to all is the fact that all the

procedures have in common the formation of a mould cavity in to which a

plastic material is poured or packed.

The mould cavity is made of two correlated parts; one forms the external

contour of the crown or fixed partial denture and the other forms the prepared

tooth surface and (when present) the edentulous ridge contact area. They are

called the external surface form (ESF) and tissue surface form (TSF)

respectively.

External surface form (ESF)

Two categories

Preformed

Custom

a. Custom ESF:

Custom ESF is a negative reproduction of either the patient’s teeth before

preparation or a modified diagnostic cast.

Custom ESF can be formed directly with any impression materials ie,

impression made in quadrant tray using alginate or silicone rubber. This can be

accurately reseated if thin areas of impression materials are trimmed using a

sharp knife (as found interproximally or around the gingival margin). Moldable

putty materials are good out of this because they can be trimmed easily reused

and also facilitates subsequent removal of the polymerized resin.

A custom ESF can be made out of transparent sheets made of cellulose acetate

or polypropylene, which comes in various sizes and thickness. A 125 x 125 mm

sheet of 0.5mm thickness is recommended for provisional restorations.

Polypropylene is preferred because it produces

Better surface detail

More tear resistant

Can be used more than once

Thermoplastic sheets are heated and adapted to a stone cast with vacuum air

pressure. Disadvantages of thermoplastic sheets are:

- It is thin

- Poor dissipater of heat

- Base plate wax can also be used to form custom ESF.

b. Preformed ESF:

They are a variety of performed crowns, which are available commercially.

They rarely satisfy the requirements of a provisional restoration, but they can be

finished to suitable form by lining with autopolymerizing resin. Most of them

require modifications (Eg: internal relief, axial recontouring, occlusal

adjustment). If extensive adjustments are required then custom ESF is always

superior. Performed ESF is always used for single restorations because using

them, as pontics are not feasible.

Tissue surface form (TSF)

There are three categories of tissue surface form, which depends on the

procedures:

Direct TSF (TSF forms the prepared tooth)

Indirect TSF (TSF forms a plaster cast or elastomer)

Indirect -direct TSF (combination of both plaster cast and patients mouth)

Techniques of making provisional restorations:

There are basically three techniques

Indirect technique.

Direct technique.

Indirect-direct technique.

1. Indirect technique:

In this technique the provisionals are produced or made outside the mouth

from a plaster cast poured out from an impression of prepared teeth and ridge

tissue.

Advantages:

No contact of free monomer with the prepared tooth or gingiva, which

may cause allergic reaction or tissue damage.

This procedure avoids subjecting the prepared tooth to the heat treated

from polymerizing resin.

The margin fit is more accurate in indirect techniques because the

restorations have been undisturbed in the stone cast. The shrinkage

caused during polymerization is restricted by stone cast while in direct

technique the distortion causes because of the removal of the restoration

before complete polymerization. Directly made long span temporaries

likely to have unacceptable marginal discrepancies due to shrinkage and

distortion

When a dimensionally stable elastomer is used as TSF it can be retained

with possible reuse with ESF. This helps the provisionals to be made

without the presence of patient there by gaining the patient’s confidence.

This technique gives the patient a chance for rest and allows the dentist to

perform other task, provided a technician is trained for it.

2. Direct technique:

The patient’s prepared teeth and gingival tissues (in the case of a partial FDP)

directly provide the TSF

Advantage:

Steps for indirect fabrications are avoided.

Convenient if adequate laboratory facilities and auxiliary personals are

not available.

Disadvantages:

Exothermic heat produced causing pulp damage.

Free monomer causes allergic reaction.

Poor marginal fit.

3. Indirect- direct techniques (Egg shell technique):

This is a combination of indirect and direct technique where a shell is first

created by indirect technique and later relined in the patient’s mouth after

preparation, which is the direct component of it.

Advantages:

Chair side time is reduced and most of the procedures are completed

before the patient’s visit.

Less heat is generated in the mouth because the volume of resin used

during lining is comparatively small.

Contact between the resin monomer and soft tissues are minimized

compared to direct procedures.

Disadvantage:

Even with the diagnostic cast method adjustments are frequently needed to seat

the shell completely on the prepared tooth.

PROCEDURES

CUSTOM INDIRECT PROVISIONAL FIXED PARTIAL DENTURES

The custom indirect procedure is probably the best overall technique for FPD’s

and should provide the most predictable results with least risk to patient health.

Technique

Two techniques can be followed

a) Template method

b) Over impression method

To make a template place a metal crown form or denture tooth in the edentulous

space on the diagnostic cast. All of the embrasures should be filled with putty.

A thin strand of putty can be placed around the periphery of the cast and on the

lingual surface of the cast apical to the teeth. Adapt the plastic sheet using

vacuum former or hand manipulating techniques. Remove the template and trim

the excess. This will give us ESF in form of a template

In an over impression technique diagnostic wax up of the pontics and abutments

can be done and then over impression is made using hydrocolloid or putty. A

laboratory knife with a no. 25 blade is used to trim off all excess material. Thin

flashes of impression material that replicate the gingival crevice are removed to

insure that there will be no impediments to the complete seating of the cast into

the overimpression later. This will give us ESF in form of over impression.

Step-by Step procedures:

1. After shade selection the tooth is prepared and impression is made out

using irreversible hydrocolloid. A sextant tray can be used if atleast one

tooth remains beyond abutments. Gingiva can be displaced if necessary.

2. Pour the impression with quick setting plaster and allow it to set for 8

minutes.

3. Remove the cast and trim excess and make sure that it fits passively and

completely with ESF. ( template/ overimpression)

4. Paint the cast with separating medium completely and allow it to dry.

5. Mark the cavosurface margin with pencil if necessary. Mix

autopolymerizing resin (methyl methacrylate) and load it into

polypropylene syringe with 2-3mm diameter tip.

6. Slowly fill the ESF with material from one side to another while keeping

the syringe tip in constant contact with the resin to avoid air bubble

entrapment and fill until the level of gingiva. Do not over fill.

7. Seat the tissue surface form into the external surface form and lightly held

together by rubber bands. The assembly is then placed in warm water 40

ºC(100 ºF) in a pressure vessel and air is applied at about 0.15 MPa (20

psi). Pressure curing will reduce porosity.

8. Remove the assembly after 5 minutes. Separate the external surface form

from the cured resin restoration, which usually remains in contact with

the tissue surface form. The bulk of the stone can be removed on a cast

trimmer and if necessary the cast can be broken to remove the restoration.

9. Eliminate resin flash with an acrylic-trimming bur and a fine-grit garnet

paper disk.

10.Contour the pontic according to the design procedures.

11.Finish the restoration with wet pumice and do not forget the gingival area

of the pontic. If necessary Robinson brush can be used on a straight hand

piece.

12.Remove any resin bleb or stone parts within the restoration and do the

try-in patients mouth.

13.The evaluation of following should be done during try-in:

Proximal contacts

Imperfections in contour

Any surface defects can be corrected by bead brush technique.

Unacceptable marginal fit can be corrected by reline technique. Occlusal

adjustment can be done if necessary using articulating paper and 12 fluted

tungsten carbide finishing bur.

14.After proper infection control procedures have done the restoration is

brought back to the laboratory for final polish using wet pumice and dry

polishing using resin compound.

DIRECT PROVISIONAL FIXED PARTIAL DENTURES

Direct technique is most commonly used for single crown restorations. An

acrylic resin other than methylmethacrylate is used in these techniques. ie,

polymer methacrylate or bisacryl can be used.

Step-by-Step procedure:

1. Make an over impression from diagnostic cast which is modified by

diagnostic waxing using putty or irreversible hydrocolloid. Check for

completeness and trim excess of material from the crevice area using BP

blade. If hydrocolloid impression wrap it in a wet paper towel and place it

in a plastic bag. This serves as ESF.

2. Alternative to this is formation of a template from a cast poured in the

overimpression.

3. After the teeth are prepared, and the soft tissue displaced from the

subgingival margins, silicone grease is applied to the prepared tooth

surfaces for protecting against the monomer.

4. Autopolymerizing resin other than polymethyl methacrylate (ie. Poly R

methacrylate or Bis-acryl composite resin) is placed in the ESF and is

seated over the prepared teeth. If plastic matrix is used patient is able to

close his teeth there by allowing the occlusion to develop more

accurately.

5. The setting of the resin should be checked at regular intervals. The

restoration must be removed during rubbery stage that is about 2 minutes

in the mouth or 6 minutes from start of mix.

6. Place the resin in a cup of warm water (37o) for 5 minutes.

7. Excess material on the restorations is trimmed and contoured.

8. The restoration is refitted to the teeth. Any marginal discrepancies can be

corrected by addition of small increments of new resin with a small hair

brush.

9. Occlusion is refined; the restoration is removed from the teeth, polished

and cemented with provisional cement.

Indirect-Direct Provisional Fixed Partial Dentures (Egg Shell Technique)

The custom indirect -direct procedure may be a good compromise when

laboratory support is not immediately available and chair time must be

minimized.

Step-by-step Procedure:

Indirect component:

1. Mount the diagnostic cast on articulator and prepare the abutment teeth

minimally or more conservatively than the eventual tooth preparation and

should have supragingival margins.

2. Make an irreversible hydrocolloid impression of the diagnostic

preparations to duplicate them in stone.

3. Coat the stone cast with separating medium and this serves as TSF.

4. Perform a diagnostic waxing procedure on the prepared articulated casts

and duplicate the wax up and pour it to form a cast.

5. A template or ESF is formed from this.

6. Make sure that the external and tissue surface forms fit together

accurately.

7. Syringe the resin into the external surface form and complete provisional

restoration.

8. If the wax has been removed from the diagnostic cast after duplication,

seat the completed provisional on it and refine the occlusion with the

articulating paper.

9. Finish and clean the preformed ESF for try in, which will follow tooth

preparation.

Direct component:

1. Prepare the patients teeth in the usual manner.

2. Try in the preformed ESF. If it is not compatible with occlusion (ie if it

does not seat completely) and the teeth have been reduced adequately, the

internal surface of the ESF should be relieved until the occlusion is

acceptable. If necessary, reduce the teeth further; the ESF should then be

re-evaluated and adjusted. The adjustment procedure might be tedious if

the preliminary steps were not properly done. This is one of the

disadvantages of indirect- direct technique.

3. Apply a uniform coat of petrolatum on the prepared abutment teeth,

gingival tissues and external surface of ESF.

4. Make a vent hole with a round bur through the occlusal (or lingual)

surface of each abutment retainer.

5. Fill the retainer with poly ‘R’ methacrylate and seat the restoration.

Placing fingertips over the vent holes can control the quantity of excess

resin expressed around the margin. When a small amount of excess resin

appears around the entire periphery of the margin, the fingertip is lifted,

allowing the trapped air and remaining excess resin to escape. Resin on

the occlusal surface can be wiped away immediately.

6. When the rubbery stage of polymerization is reached (about 2 minutes in

the mouth) engage the facial and lingual surfaces of an abutment retainer

with Backhaus forceps and rock the restoration buccolingually to loosen

it. Move to the other retainer and do the same.

7. Remove the restoration and place it in warm water to hasten

polymerization for 5 minutes.

8. Mark the margins with a sharp pencil and eliminate the excess resin. The

bulk can be removed with an acrylic resin trimming bur or carborundom

disk. A fine grit garnet paper disk completes axial shaping.

9. Confirm the marginal fit and occlusion refinish and polish wherever

necessary and cement the restoration.

Custom single unit provisional restorations:

a. Complete Crowns:

Single unit complete crowns or splinted crowns may be made directly or

indirectly. Because pontics are not involved, creating an external surface form is

simpler. Diagnostic procedures or wax up is not required unless if extensive

changes are required Eg: increase in vertical dimension. If this is not there an

alginate impression is only required before tooth preparation which serves as

ESF either directly or indirectly.

b. Onlay and partial veneer crowns:

Making onlay and inlay are similar to the custom single crowns. The

provisional may easily be distorted on handling because of the conservative

tooth preparation that interrupts the continuity of the axial wall. They can be

made directly or indirectly. The direct method should be carefully handled and

better results are expected with the indirect method.

Points to be noted:

1. When trimming the polymerized resin to the margin, leaving excess resin at

the occlusal cavosurface margin is recommended because this will help to

prevent fracture of enamel at this area because of the low strength of the resin

when compared to metal.

2. There is no need to give vent holes if lining procedures are required because

adequate space is there for the resin to escape.

c) Inlays

Inlays present the problem of being small and difficult to handle, especially

during trimming. Making interim restorations requires a number of

modifications.

Step-by-step procedure:

1. For a two-or three surface inlays apply the matrix band and wedges in the

same manner for class II amalgam restoration. The band must seal all aspects of

the proximal cavo surface margins.

2. Apply petrolatum in all sides of cavity preparation by using small cotton

pellets.

3. Make a handle to remove the resin using unwaxed dental floss preferably 2 to

3 cm long by placing one end in to the preparation cavity.

4. Mix small amount of poly ‘R’ methacrylate and introduce it in to the cavity

during dough stage using an amalgam condenser.

5. Be careful not to push in to undercuts past the matrix and remove excess of

material immediately using spoon excavator.

6. Monitor the resin with a hand instrument by light probing. When the resin

reaches the late rubbery stage remove it by tugging. The floss handled with

cotton roll forceps along the path of withdrawal.

7. Place the resin in a cup of warm water (37oC) for 5 minutes.

8. Mark the margins with a sharp pencil and trim away any flash.

9. Return it back to the cavity preparation and check for occlusion and adjust

using slow speed hand piece.

10. Remove the restoration and make the definitive impression and then cement

the provisional restoration.

11. Remove the excess cement using explorer and spoon excavator. Carefully

cut of the floss handle with scalpel blade.

d. Laminate Veneers:

Step by step procedure:

1. Select the most appropriate composite resin shade or combination of shades

before preparing the tooth.

2. Apply a thin layer of petrolatum when tooth preparation is complete to the

prepared tooth surface.

3. Form the preselected shade of light cured resin using plastic instrument on

the prepared surface. Curing can also be accomplished by incremental curing

technique.

4. Light cure the resin and remove it from the tooth surface.

5. Thoroughly clean the petrolatum from the tooth surface and internal surface

of the veneer. Apply etching gel to three 1mm diameter areas to form an

equilateral triangle. (Two corners at the mesioincisal and distoincisal line angles

and the third centered more cervically) Allow the etchant to remain for 20

seconds. Rinse completely with water and dry.

6. Place unfilled bonding agent in the etched areas and immediately place the

veneer on the tooth. Hold it in place and light cure for 10 seconds. Remove any

excess bonding agent, and then cure for 60 seconds.

7. At the patients return visits remove the veneers using a spoon excavator.

Alternative method: Another method is by forming the veneers indirectly by

creating a TSF and an ESF, in the same manner for fixed partial provisional

restoration. This method is very efficient especially if multiple veneers are to be

made.

e. Post and Core provisional restorations:

Step-by-step procedure:

1. A piece of wire (Eg: a straightened paper clip) is placed in the post space, so

that it extends passively to the end of the space

2. At the mouth of the post space the wire is marked using a pencil and a 180º

bend is made using pliers.

3. Lubricate the tooth and surrounding soft tissue with petrolatum. Paper points

may be used to lubricate the post space.

4. Fill the ESF with provisional resin (poly ‘R’ methacrylate is recommended).

5. When the resin loses its surface gloss, place the wire in the post space and

seat the ESF over it. Care should be taken to protect the patient from aspirating

the wire.

6. Remove the ESF while the resin is still rubbery (about 2 to 2 1/2 minutes).

The stage of polymerization can be monitored. Usually the provisional comes

along with the ESF if it doesn’t, it should be removed and then reseated several

times and then removed before the resin fully polymerizes.

7. Put the restoration in water. Care should be taken not to disturb the wire.

8. Mark the margins with a pencil and trim and contour the restoration with

disks or carbide burs.

9. Try in the restoration and adjust as necessary. Polish, clean and cement the

restoration.

Template fabricated VLC provisional restorations:

A transparent template is required as ESF is required to use visible light

cured (VLC) to fabricate provisional restoration. It can be fabricated using

direct or indirect techniques.

Step-by-step procedure:

1. Fabricate a template ESF using a duplicated cast from diagnostic wax up.

2. Trim the template as required and replace it back on the cast. Mix a scoop of

silicone putty and mold it around the template to prevent displacement by the

highly viscous resin later.

3. Make an alginate impression after the tooth preparation and pour a cast in

quickset plaster. Coat the cast with separating media.

4. Lay a stand of resin inside the template and also around the margins of the

preparation. (Enamel resin can be used in the incisal or occlusal portion first to

enhance esthetics on the cast)

5. Seat the template using firm pressure. Compress the silicone putty index over

the template to insure complete seating of the template and an even thickness of

resin in the provisional restoration. Remove the putty index from the cast

leaving the resin and template in position on the cast.

6. Place the cast in triad curing unit to polymerize the resin in the template for 4

minutes.

7. Carefully remove the template and then the provisional restoration from the

cast. Paint all surfaces of the restoration with air barrier coating material.

8. Place the provisional back in the curing unit, tissue side up for an additional 6

minutes. Retrieve the restoration from the curing unit and remove the entire air

barrier coating material with a brush and water.

9. Trim as much excess material as possible with a pair of curved scissors.

Finish trimming the axial surfaces to the margins with discs. Open the

embrasures around the pontic with discs and burs. Remove the saddle form and

highly polish the restoration.

In an alternative technique the restoration can be cured directly in the mouth

using hand held curing light for 10 seconds. After the restoration is frozen in

this manner it is removed from the mouth and further exposed to high intensity

curing light in the laboratory.

PREFABRICATED PROVISIONAL RESTORATIONS

A custom external surface form will produce the best results in the shortest

time in most circumstances. But there will be times when a custom ESF or time

recommended is not available for example, first-visit emergency in which

crown is missing and must be replaced. In these cases a preformed crown can be

employed to protect the tooth for sufficient time moreover, this can gain

patient’s confidence also.

a. Polycarbonate crown forms:

They are useful for provisional restorations on single anterior teeth and

premolars. They frequently will require extensive alteration to correct

morphologic discrepancies and improper contours. If they are not carefully

contoured, they will have horizontal overhangs that will be damaging to the

gingiva. They need to be lined with resin to meet the basic requirements.

Step-by Step procedures:

1. Measure the mesio-distal width of the crown space with dividers and select a

shell with the same or slightly larger width. (Shade can be selected using shade

guide provided).

2. Mark the crown height (From the incisal edge) with a pencil. The distance

from the pencil mark to the margin should equal the length discrepancy between

the incisal edge of the crown form and the incisal edges of the adjacent teeth.

The excess gingival length is trimmed away with a large carborundom stone or

an acrylic bur, using the pencil line as a reference mark.

3. Try the shell on the prepared tooth. The incisal edges and labial surface of the

shell should align properly with those of adjacent teeth. The internal surface of

the shell may often need reduction to achieve this match. Occlusion can be

adjusted later since it is possible to adjust it after reline. When the shell can be

properly positioned without forceful gingival contact, it is ready to be lined by

resin.

4. Apply a uniformly thin coat of petrolatum to the prepared teeth and adjacent

gingiva. This will prevent direct contact of the monomer with these tissues.

5. Mix the autopolymerizing resin and fill the shell (poly R’ methacrylate).

When the surface just loses its gloss or the resin forms a peak without slumping,

place the shell over the tooth and align incisal and labial surfaces with those of

the adjacent teeth.

6. Immediately eliminate any marginal excess and once the rubbery stage of

polymerization is reached (about 2 minutes) rock the crown faciolingually to

loosen and remove it.

7. Keep reseating and removing the crown few times and then put it in warm

water (37ºC).

8. When the resin has fully polymerized mark the margins with a sharp pencil.

The axial surfaces can be shaped and flash eliminated with straight hand piece

carbide burs and disks.

9. Try on the newly lined crown and adjust the lingual surfaces to desired

occlusion and contour using articulating paper.

10. Remove the crown out, and smooth out the rough abraded areas in the

lingual and incisal areas as well as those surfaces recontoured near the margin

with a Burlew wheel in the straight hand piece.

11. Polish all surfaces of the provisional restoration with polishing compound

and cement the restoration.

Alternative technique:

The relining of the polycarbonate shell can be done indirectly also. Here the

tooth preparation is done and an impression is made using alginate. The

impression is poured in quick set plaster. The cast is obtained and the crown

selected and the procedure is done. Polymethyl methacrylate can be used here.

b. Preformed Metal Crowns:

Emergency cases involving fractured molars are one of the best indications

for the use of preformed metal crowns. Zinc oxide and Eugenol alone will not

adhere to the tooth, and there is rarely enough time at the emergency

appointment to fabricate a custom acrylic resin provisional crown. By using the

preformed anatomic metal crown, it is possible to provide the patient with

temporary coverage to protect both the tooth and tongue. This procedure

consists of:

Minimal tooth preparation

Measurement and selection of crown.

Trimming and adaptation of gingival margin

Occlusal adjustment

Cementation

Step-by-Step procedure:

1. The tooth should be prepared minimally to create space for the restoration.

Occlusal reduction, which follows the inclined planes.

1mm on the non-functional

1.5mm on the functional cusps.

Functional cusp bevel is given is placed to a dentin of 1.5mm to

complete the occlusal reduction.

Slight proximal reduction is done to permit the seating of crown.

2. Measure the mesiodistal width of the crown space with dividers and select an

appropriate shell type with a width as close as possible. A slightly larger or

smaller shell can be deformed with contouring pliers to achieve the proper fit.

3. Measure the occlusocervical height and trim the shell with crown and collar

scissors. So that it extends about 1mm apical to the cavo surface margin. Sharp

margins should be smoothed using burs.

4. Place the trimmed shell over the prepared tooth and gradually apply seating

pressure while observing the gingiva. Trim the margins further wherever the

gingiva blanches. The shell margins should not engage the prepared tooth

margin.

5. If it is an aluminum shell the patient can be asked to close with moderate

force. The soft aluminum should deform until normal intercuspation reaches.

6. Apply petrolatum to prepared tooth and adjacent gingival tissues, mix poly R’

methacrylate and fill the shell.

7. When the resin loses its gloss surface place the shell over the tooth and guide

it to a slight supraocclusal position and ask the patient to close.

8. Immediately remove the excess. When rubbery stage is reached remove the

crown with Backhaus forceps. Loosen and remove the crown by rocking it

buccolingually or by using the thumb and index finger of the other hand to

apply occlusally directed force.

9. Place the shell in a cup of warm water (37oC) for five minutes.

10. Mark the margins and trim away any excess. To establish periodontally

healthy axial contours, the aluminum shell frequently is ground away in certain

areas.

11. Replace the crown and adjust the occlusion as deemed necessary. If

proximal surface lack contact, resin can be added to correct the deficiency.

12. Polish clean and cement the restoration.

High strength provisional restorations:

Indications:

A long span posterior FPD

Prolonged treatment time

Patient unable to avoid excessive forces on the prosthesis.

Above average masticatory muscle strength.

History of frequent breakage.

Examples:

- Cast metal

- Fiber reinforced

- Heat cured provisional restorations

Heat cured provisional restorations:

1. A thin plastic matrix is made out from diagnostic wax up.

2. After the tooth preparation, an impression is made and a cast is poured.

3. The matrix is filled with ivory- coloured wax and guided in to position upon

the cast after applying wax release agent.

4. The waxed up restoration is invested in a suitable flask and heat cure resin

with appropriate shade is used to process.

5. The resin is polymerized by immersing in water at 100ºC for 30 to 60

minutes.

6. Gross trimming of the resin is accomplished with large burs and disks.

7. Contouring is refined with small laboratory burs to trim marginal areas and

blend facial and lingual contours in to the proximal embrasures.

8. The occlusion should be adjusted to provide positive uniform but minimal

contact areas in maximal intercuspal position. Contact in lateral excursions

should be eliminated if possible in the posterior region and provide proper even

contact in the anterior.

9. Polishing of the smooth axial surfaces of the restorations should be

performed with pumice and rag wheel running at slow speed. Interproximal

areas should be polished with flexible rubber cup and pumice.

CEMENTATION

The primary function of the provisional luting agent is to provide a seal,

preventing marginal leakage and pulp irritation. The luting agent should not be

relied upon to resist occlusal forces, because it is purposely formulated to have

low strength. Unintentional displacement of a provisional restoration is

frequently caused by a non-retentive tooth preparation or excessive cement

space rather than the choice of luting agent.

Materials:

Zinc oxide eugenol cement is the most satisfactory material. Weaker ZOE

cements allow easy removal, which enables reuse of the restoration.

Advantages of zinc eugenol cement:

They are weaker cements and facilitate easy removal.

They have acceptable sealing properties.

They have obtundent effect on the pulp.

Disadvantages of zinc oxide eugenol:

Free Eugenol acts as plasticizer of methacrylate resin and affect its

surface hardness and strength.

They results in softening of the resin, which is added to, polymerized

resin previously in contact with free eugenol. The R-methacrylates are

more affected followed by methyl methacrylate and composites.

They have shown to reduce the tensile bond strength of resin luting

agents.

In situations when the tooth preparation lacks retention, when a span is great

or long term use is anticipated or when parafunction exists, using higher

strength cements may be desirable. A good compromise would be reinforced

zinc oxide eugenol or eugenol free zinc oxide, which has slightly greater

strength than zinc oxide eugenol.

Points to be noted:

Correct proportions of the cements should be mixed to reduce unreacted

or free eugenol as much as possible.

Residue of ZOE or non-eugenol cement can reduce the tensile bond

strength of resin luting agents.

Air abrasion with aluminum oxide or etching with 37% phosphoric acid

after cleaning with pumice may be done to remove ZOE.

Step-By-Step procedure for cementation:

1. Apply petrolatum to the polished external surfaces of the restoration to

facilitate easy removal of excess cement.

2. Mix the material and apply a small quantity just occlusal to the cavosurface

margin. A marginal bead of cement forms the required seal against oral fluids.

Filling the crown or abutment retainers should not be done, because it increases

the risk of debris in the sulcus and prolongs clean up.

3. Seat the restoration and allow the cement to set.

4. Carefully remove excess with an explorer and dental floss.

5. The sulcus should be checked for remnants and irrigated with air water

syringe or else can lead to severe periodontal problems

Removal, Recementation, and Repair:

The provisional restoration must be removed either for cementation of

definitive restoration or modification of tooth preparation.

Removal forces must be directed parallel to the long axis of the

preparation. The backhaus forceps or haemostatic forceps is effective on

a single unit. A slight buccolingual rocking motion will help to break the

cement seal.

Damages are most common in removal of fixed partial denture ie, if one

abutment retainer suddenly breaks, the other can be subjected to severe

flexure stresses where FPD acts as a lever arm. Looping dental floss

under connector at each end of the FPD might be helpful.

Step-by step procedures for recementation:

1. Clean out the bulk of previous cement with a spoon excavator and by placing

the provisional in a cement -dissolving solution and setting it in the ultrasonic

cleaner.

2. If required, line the provisional restoration again and cement it.

Repairs can be accomplished by adding resin by bead-brush technique.

CONCLUSION

Quality restorative dentistry needs quality provisional restorations for

predictable results. Dentists therefore need to be familiar with the range of

materials and techniques for short term, medium-term and long-term

temporization. Forethought and planning are also needed to ensure the most

appropriate provisional is used, especially when multiple teeth are to be

prepared or where occlusal or aesthetic changes are envisaged. Such changes

are best tried out with provisionals so that modifications can easily be made

intra-orally and when satisfactory copied into the definitive restorations. In this

respect an initial diagnostic wax-up is invaluable to facilitate the construction of

laboratory formed provisionals or matrices.

REFERENCES

1. Rosenstiel, Land, Fujimoto. Contemporary fixed prosthodontics.2006 4 th

ed.

2. H.T Shillingburg, Sumiya Hobo, Lowell D. Whitsett. Fundamentals of

fixed Prosthodontics.1997 3rd ed

3. Dental Laboratory Procedures: Rudd Morrow. 2nd edition

4. Bennani, V (2000)Fabrication of an indirect-direct provisional fixed partial

denture. J Prosthet Dent. Sep;84(3):364-5

5. Wassell RW, Barker D, Steele JG. (2002) Crowns and other extra-coronal

restorations: provisional restorations. Br Dent J. Jun 15;192:619-630.

6. Burns DR, Beck DA & Nelson SK. (2003) A review of selected dental

literature on contemporary provisional fixed prosthodontic treatment: report

of the Committee on Research in Fixed Prosthodontics of the Academy of

Fixed Prosthodontics J Prosthet Dent. Nov; 90(5):474-97.

7. Christensen, GJ. (2004) Making provisional restoration easy predictable

and economical. JADA, vol 135 :625-627