Sireen Meheshi

Professor assistant of fixed

prosthodontics,Tripoli University
MS,PhD cairo University.
1.Introduction and definition
2.Synonyms
3.Indications ,advantage and functions.
4.Classification of provisional restoration.
5.Properties of provisional materials.
6.Materials and Techniques of fabrication.
7.Cementation for provisional restorations
8.Evalatution of provisional restorations
FUNCTION
Biological Requirements
1.Pulpal protection.
A provisional restoration must seal the prepared
tooth Surface from the oral environment to prevent
Sensitivity and further irritation to the pulp
In severe situation’s leakage can cause irreversible
pulpitis And the resulting need for root canal
treatment.
Factors contributing to pulp death:
•Preparation trauma
•Microbial exposure
•Desiccation
•Chemical exposure
•Thermal exposure
Biological Requirements
2.Preiodontal health.
Must have good marginal fit ,proper contour and a
smooth surface. If the provisional restoration is
inadequate and plaque control is impaired ,gingival
health will deteriorate when gingival tissue is
impinged upon, ischemia is likely fit is not corrected,
localized inflammation or necrosis will develop.
(Easily cleaned, Nonimpinging margins and
proper contour)
Biological Requirements
3.Positional stability and Occlusal function.
The provisional restoration should establish or maintain
proper contacts with adjacent and opposing teeth. Inadequate
contacts allow supraeruption and horizontal movements.
Horizontal movements results in excessive or deficient
proximal contacts.
Properly contoured and fitted provisional restoration maintain
the position of gingival tissue.
-Maintain the normal esthetic position of the lip.
-The design of the temporary bridge pontic should prevent
ridge alteration by providing normal embrasure and not ridge
impinging
Biological Requirements
4.Strength,retention and prevention of enamel
fracture

• The provisional restoration should protect

crown preparation margins.

• A small chip of enamel will make the definitive

restoration unsatisfactory and necessitate a
time consuming remake.
Mechanical Requirements
1.Function:
• The greatest stresses in a provisional
restoration are likely to occur during Chewing.
• An FPD must function as a beam on which
substantial occlusal forces are transmitted to
the abutments.
• High stresses in the connectors which are
common site of failure, so the connectors size
increased compared to final restorations(by
dec sharpness and depth of embrasures Anterior region over contouring is limited with
• Good access for plaque control must be a esthetics while posteriorly is less restrictive but
high priority not to jeopardize the maintenance of
periodontal health
• 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.

Fiber-reinforced composite
fixed partial denture
Mechanical Requirements
2.Displacement:

• To avoid irritation to the pulp and tooth movement, a displaced provisional must be
recemented promptly

• Displacement is best prevented through proper tooth preparation and a provisional with
a closely adopted internal surface

• Excessive space between the restoration and the tooth places greater compressive, tensile,
and shear forces on the luting agent, which has lower strength than regular cement and
thus fractures under the added force.

• For this and for biologic reasons, unlined preformed crowns should be avoided
Mechanical Requirements
3.Removal for Reuse:
If the cement is sufficiently weak and the interim restoration has been well fabricated at an
optimal thickness, it does not break upon removal

4.Diagnostic Requirements:
In cases of teeth wear or multiple restorative procedures that have severely
Altered tooth anatomy
Changes to functional and interarch relationships can be evaluated with interim
restorations.
These changes can be in the form of alterations to the occlusal plane, anterior guidance,
functional patterns, occlusal vertical dimension, incisal edge position, tooth colour and
length
• Interim restorations are based on a diagnostic waxing after appropriate clinical records
have been made (TEST DRIVE)
Occlusion is not correct or, at least, not compatible with the patient’s functional and
parafunctional movements

Or

The resistance/retention form of the tooth preparations is inadequate.

• This acrylic resin interim crown fractured. The

interocclusal
• record between the preparation and its antagonist
shows that the preparation was underreduced
Esthetic Requirements:
• It should match shape, color ,size and texture of the restored tooth especially in the
anterior region (Appropriate emergence profile and proximal contour ).

• Color stability is also important if the provisional are to function for prolonged
period

• The provisional is often used as a guide to achieving optimum esthetics in the

definitive restoration.

• Beauty and personal appearance are highly subjective and difficult to communicate
verbally, and a facsimile prosthesis can play a vital role in the patient’s consideration
of esthetics and the impact that the prosthesis will have on self image.

• The provisional is shaped and modified until its appearance is mutually acceptable to
the dentist and the patient.

• Involving the patient in decision making increases the patient’s satisfaction.

 Contour
(diagnostic wax up)

Color
(paint on stain kit)

Translucency
(layering with translucent resin)

Surface texture
(during waxing up
or coarse diamond rotary instruments)
• Convenient handling: adequate working time, easy
molding, rapid setting time
• Biocompatibility: nontoxic, nonallergenic, nonexothermic
• Dimensional stability during solidification
• Ease of contouring and polishing
• Adequate strength and abrasion resistance
• Good appearance: translucent, color controllable, color
stable
• Good acceptability to patient: nonirritating, odorless
• Ease of adding to or repairing
• Chemical compatibility with interim luting agents
• Are divided into four resin groups used either conventionally or
digital techniques:
• PMMA
• Poly R’ methacrylate
• Bis-acryl (bis-GMA)
• Light-polymerized resin
• Recently a new resin is introduced which has no free monomer and minimal
heat production ( Ethylene imine resin).

• Overall performance of the groups are similar ,the choice of

the material should be based on the condition for more
successful results
 Polymethyl
methacrylate
(PMMA) resins

A poly-R′ methacrylate resin. Microfilled composite resins with Photopolymerized polymethyl

automix delivery system. methacrylate.
 Dimensional changes
For auto (shrink and marginal
Better used indirect

polymerizing discrepancy)
Some materials
Impression made
materials Interact with
impression material
before direct interim
Restoration

Powder- Exothermic
Better used indirect
Not entirely
liquid resins biocompatible

Although has
Used when long span
CAD/CAM Superior internal
adaptation but
prosthesis or high
MATERIALS require additional
software
strength needed or
long term provisional
a.Conventional (External surface form
or preparation surface form)
b.Digital
c.combination
 External surface form (ESF)

Custom template Preformed

Fabricated by
a) Negative reproduction of either pt’s teeth before prep Performed used with relining with autopolymerized resin
b)Or Diagnostic cast modified with waxing Or digitally designed as “shell” type CAD/CAM

Material used
Base plate wax or thermoplastic sheets or transparent Polycarbonate,cellulose acetate,metal preformed
sheets (cellulose acetate or polyporpoylene) anatomical or non anatomical
Step by step procedures for fabrication of custom
made temporary restorations:
A) Direct technique :

1- A mold of the desired form of the restoration is

fabricated using either :
- Alginate impression
- Vacuum formed plastic shell.
- Heavy body rubber base impression.
Before taking impression the cast is corrected for any abutment defects
and any missing teeth should be replaced by denture tooth or wax
1- Mix a suitable amount of Heavy body
rubber base impression.
 The mixed rubber base is applied to the area of
preparation.
 Apply a separating medium to
the preparation area.
The mixed resin is applied to the
inside of the impression ( mold).
The impression is reseated
inside the patient mouth.
Cementation of the The excess resin is removed and
restoration finishing is performed
A)flexible putty material for making external
surface forms
B)after heating ,the sheet is applied on stone
cast
C)electric heating element and vaccum source.
D)Trimmed polypropylene external surface form
E)Automated positive pressure thermal forming
machine
PREFORMED MATERIALS:

Preformed provisional crowns or matrices usually consist of tooth-

shaped shells of plastic, cellulose acetate, or metal.

They are commonly relined with acrylic resin to provide a more custom
fit before cementation, but the plastic and metal crown shells can also be
cemented directly onto prepared teeth using a stiff luting material
following adjustment They are commercially available in various tooth
sizes and are usually selected for a particular tooth anatomy.
Resin:
Celullose and
polycarbonate crowns

Metal:
Non-
anatomical
form and
anatomical
form
stainless
steel and
aluminum
crowns
Disadvantages:
1-limited to posterior areas
2- Poor esthetic
3-Rapid wear resulting in perforation
2-Polycarbonate:
Advantages:
high impact strength
abrasion resistance
hardness
good bond with methyl-methacrylate resin
CAD-CAM PMMA or composite resin:
CAD-CAM crowns can also be preformed and then lined at chair side. can be produced in either
monochromatic blocks or produced in a multilayered form with different levels of chroma from
gingival to incisal for a more lifelike looking restoration
 PREPARATION SURFACE FORM (PSF)
Indirect-Direct(using custom made preformed
Indirect(impression for lab procedures) Direct (intra oral procedures) ESF)

All three require either a lining procedure or remargination cause of the limitation of
materials
Can be accomplished with a conventional or digital workflow

Materials Used
Autopolymerized PMMA
Bis-acryl resins
Poly R’ Methacrylate PMMA or poly R’ methacrylate
or Digital scanning (milled PMMA)
(free monomer or exothermic reaction)

Special considerations
Stone cast restrict shrinkage during polymerization Volume of resin used is reduced so less heat
Shrink less and heat less but less flexure strength than
Heat dissipated on cast better than intra-orally to avoid PMMA For FPD no monomer contact in pontic(s) but more lab cost
pulp damage and time
Indirect technique
 A B c

D E F
(A) Indirect technique: ESF is an alginate impression; PSF, a quick-set plaster cast.
(B) Direct technique: ESF is a baseplate wax impression; PSF, the patient.
(C) Direct technique:ESF is a vacuum-formed acetate sheet; PSF, the patient. (D) Direct technique: ESF is a polycarbonate preformed shell; PSF, the
patient.
(E)Indirect-direct technique: ESF is a custom preformed three-unit fixed partial denture shell (maxillary right central incisor to canine) made indirectly; PSF,
the patient.
(F) Indirect technique: ESF is a silicone putty impression; PSF, a quick-set plaster cast of the preparations.
Summary of techniques used to fabricate provisional crowns
 Acrylic
PLASTIC Cellulose crown
polycarbonate
Preformed
crowns Aluminum
METAL Stainless steel
Nickel chromium

Classification REINFORCEMENT CAST METAL

FIBERS
MATERIAL
according to type
of material Self or light cure
resin/custom
fabricated
Zinc oxide and eugenol
Non-eugenol material
Provisional
cement Calicum hydroxide
Resin based temporary
cement
TYPES OF CEMENT USED :

• Eugenol containing temporary

cement.

• Eugenol free temporary

cement.

• Resin based temporary

cement.

• Calcium hydroxide temporary

cement.
 Seal against leakage of oral fluids
 strength when intentionally removed
 Low solubility
 Chemical compatibility with the interim polymer
 Convenience of dispensing and mixing
 Ease of elimination excess
 Adequate working time and short setting time
Should be evaluated in the patient’s mouth for :

 Proximal contacts
 Contour
 Surface defects
 Marginal fit (can be corrected by finishing or addition)
 Occlusion (checked by articulating paper and adjusted with finishing
bur)
 Deficient proximal contacts, imprefections in contour or surface defects can be corrected by addition of flowable
composite for bis-arcyl but surface must be first cleaned with 15 sec phosphoric acid then light cured

Flowable composite
used to improve
adaptation of finish line
 Thank you
Any questions ?