3. FPD provisionals ✅

provisional

fixed or removable dental prosthesis, or maxillofacial prosthesis designed to enhance esthetics, stabilization, and/or function for a limited period of time, after which it is to be replaced by a definitive dental or maxillofacial prosthesis;

often such prostheses are used to assist in determination of the therapeutic effectiveness of a specific treatment plan or the form and function of the planned definitive prosthesis

The terms provisional, interim or transitional is used instead of temporary restoration

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

Provisional crowns or Fixed partial dentures are essential to prosthodontic therapy.

The function of interim treatment

1. is to protect the pulp and periodontium,

2. to promote guided tissue healing in achieve an acceptable emergence profile

3. to evaluate hygiene procedures,

4. to prevent displacement of abutments,

5. to improve esthetics and correct pronunciation, provide adequate occlusal
scheme and evaluate intermaxillary relationship

Requirements of provisionals

An optimal provisional restoration must satisfy many interrelated factors, which can be classified as

Biological

Mechanical

Esthetic

Biological requirements

Protection of pulp

Occlusal compatibility

Maintenance of periodontal health

Maintain tooth position

Protect against fracture

BIOLOGIC: Pulp protection (why?, how?)

Why: During tooth preparation sectioning of the dentinal tubules a certain degree of pulp trauma is inevitable.

How: Provisional restoration must seal and insulate the prepared tooth surface from the oral environment to prevent sensitivity & further irritation to the pulp.

In severe situations, leakage can cause irreversible pulpitis and resulting need for root canal treatment.

Biologic/Periodontal health(how?, when?)

How: Facilitate plaque removal: a provisional restoration must
have good marginal fit, proper contour & a smooth surface.

When: This is particularly important when the crown margin is to be placed apical to the free gingival margin.

If the provisional restoration is inadequate plaque control is impaired and gingival health will deteriorate.

biologic: Occlusal compatibility & Tooth position

The provisional restoration should establish or maintain proper contacts with adjacent & opposing teeth.

Inadequate contacts allow supra-eruption and horizontal movement of the teeth.

Correction requires tedious chair side & laboratory procedure

Supraeruption

detected at try in when the definitive restoration makes premature contact.

Horizontal movement

results in excessive or deficient proximal contacts which often leads to
compromised proximal contours & impairs oral hygiene measures

Biologic: Prevention of enamel fracture.

The provisional restoration should protect the crown preparation margins.

This is particularly important in partial coverage restorations in which the margin of the preparation is close to the occlusal surface of the tooth & could be damaged during chewing

Mechanical

Resist against functional loads

Removal for reuse

Maintain interabutment alignment

MECHANICAL: Resist functional load

The greatest stresses on a provisional restoration is likely to occur during chewing, similar to those occurring in the definitive restoration.

The strength of PMMA resin is about one twentieth of the metal or ceramic, Bis- acryl is one-fourth to one-fifth of ceramic making fracture of the provisional restoration much more likely.

In some instances high strength provisionals i.e. cast metal, fiber reinforced, or heat processed resin can spare the practitioner & the patient inconvenience & the expense of remaking the restoration

Indications for high strength provisional restorations

Long span posterior fixed partial denture

Prolonged treatment time

Patient unable to avoid excessive force on the prosthesis

Above average masticatory muscle strength

History of frequent breakage

Long-term provisional restorations: Fiber-reinforced fixed prostheses

consist of a fiber-reinforced composite (FRC) substructure veneered with a particulate composite material.

The substructure provides strength, and because it is laboratory processed, exhibits better physical properties and esthetics than do direct placement acrylic interims.

They are ideal prostheses when a longer-term interim restoration is necessary

mechanical: retention

It should have close adaptation to the prepared tooth surface to prevent displacement and recementation, which will increase patient visits.

removal for reuse

Provisional restoration may need to be removed and recemented often.

If they are well fabricated with adequate thickness and cemented with weak cement they can be removed without breakage

Esthetic

Easily contourable

Color compatibility

Translucency

Color stability

The appearance of the provisional restoration is particularly
important for anteriors.

Contour, color, translucency & texture are essential attributes.

Often used as a guide in achieving optimum esthetics in the definitive restoration as it greatly influences appearance, the patient consideration for esthetics & the impact that the prosthesis will have on the self image

Types of Provisionals

CUSTOM MADE PROVISIONALS( TSF)

Made with index derived from original teeth or from modified diagnostic cast

direct

Fabricated using an index that is lined with provisional material and placed directly over the prepared teeth inside the patient’s mouth

indirect

Fabricated by placing the index filled with provisional material over a cast of prepared teeth, outside the patient’s mouth

indirect direct

Fabricated by forming temporaries in an indirect manner and then relining it directly in the patient’s mouth

PREFABRICATED PROVISIONALS(ESF)

Preformed crowns which can be modified to fit the prepared tooth.

They can be relined

All the procedures have in common is the formation of a mold cavity into which plastic materials are poured or packed

Surface Forms in Provisionals

1. external surface form (prefabricated)

2. tissue surface form (custom made)

Both ESF and TSF are essential for accurate, functional provisionals

External Surface Form (ESF)/ prefabricated

The outer shell of a provisional dental restoration, created to serve as a temporary crown or bridge while a permanent one is fabricated.

It is called "external" because it forms the tooth's exterior contour and "form" because it shapes it

Tissue Surface Form (TSF) /custom made :

internal mold – adapts to prepared tooth & gingiva

Made from negative reproduction of patient’s teeth (before prep) or diagnostic cast

Obtained using any impression material

Common methods:
• Quadrant tray impressions (alginate/silicone)
• Moldable putty matrices
*Advantages of putty: easy to trim, flexible, simple removal after polymerizate

Tissue surface form: Direct form

Provisionals fabricated directly in the mouth over the prepared teeth

Tissue surface form: Indirect form

an impression is made of the prepared teeth & the ridge tissue which is poured in quick setting plaster.

The Provisionals are fabricated outside the mouth

Tissue surface form: Indirect Direct form

Fabricated on the mock prepared, wax up cast before preparation and then lined inside the mouth after the teeth are prepared

Preformed External Surface Form (ESF) (Prefabricated)

Ready-made crown shells (polycarbonate, celluloid, aluminum, Ni-Cr, etc.)

Function as molds – must be relined with autopolymerizing resin

Best suited for single-unit Provisionals

Require modification for contour, fit, and esthetics

Prefabricated Provisionals

Polycarbonate crowns

Polycarbonate has the most natural appearance of all the preformed materials. when properly selected & modified its appearance rivals a well executed porcelain restoration & is very color stable resin.

Although it is available in only one shade this can be modified to limited extent by the lining resin.

Polycarbonate crowns are supplied in incisor, canine and premolar tooth types only.

Cellulose acetate

Cellulose acetate is a thin (0.2 to 0.3 mm) transparent material available in all tooth types & a range of sizes.

Shades are entirely on the auto polymerizing resin.

The resin does not chemically or mechanically bond to the inside surface of the shell, once the polymerization is complete the shell is peeled off & discarded to prevent staining at the interface.

Aluminum and tin silver

Aluminum & tin silver are suitable for the posterior teeth

most The elaborate forms have anatomically shaped occlusal & axial surfaces.

The most basic & least expensive forms are merely cylindrical shell resembling a tin can.

Care must be taken to avoid fracturing the delicate cavosurafce margin of the tooth preparation when fitting the crown as these crowns have cervical constricted contour.

Nickel-Chromium

shells are used primarily for children with extensively damaged primary teeth

In that application they are lined with resin but are trimmed, adapted with contouring pliers & luted with high strength cement

They can be used for permanent teeth but are most suitable for the primary teeth

Nickel-Chromium alloy is very hard & therefore can be used for long term provisional restorations

Provisional restoration materials can be divided into two groups according to their chemical composition:

1. Monomethacrylates or acrylic resins
which include polymethylmethacrylate (PMMA) and polyethyl/butyl
methacrylate (PEMA);

2. Dimethacrylates or bis-acryl/composite resins
such as bisphenol A-glycidyl dimethacrylate (Bis-GMA) and urethane
dimethacrylate (UDMA; (these resins are polymerized by light)

PMMA advantages and disadvantages

Bis- GMA advantages and disadvantages

Materials used for interim fabrication

Alike® PMMA (Polymethyl methacrylate), also known as acrylic.

It is imperative for you to mix the material properly to reduce shrinkage.

The basic concepts for interim fabrication were discussed in detail in Single Crown course.

Bis-acylic resins temporary crown and bridge materials indications

Temporary crowns and bridges

Temporary inlays and onlays

Partial crowns

Veneers

Long-term temporaries

provisa vs alike

Bis Acrylic Provisionals advantages: Advantage

Self-cure

Self-mixing double-body syringes to allow for the homogenization

Direct application into the impression

Methyl methacrylate free

Low heat generation during polymerization

High flexural strength

Low curing time

SHADE options: A1, A2, A3, A3.5, B1, Bleach

Bis Acrylic Provisionals advantages: Disadvantage

Cost (High cost)

Slight learning curve on how to use

In a long term provisional situation, not recommended to be repaired due to decrease flexural strength- a new interim should be made at that time

PMMAs are considered to exhibit higher fracture toughness than bisphenol A glycidyl methacrylate (bis-GMA) resins and hence is recommended where additional strength is required or for long term provisionalization.

Ideal provisional material should have the following properties

Convenient handling-adequate working time, easy moldability, rapid setting time.

Bio-compatibility-Nontoxic ,non allergenic ,non exothermic.

Dimensional stability during polymerization.

Ease of contouring & polishing.

Adequate strength & abrasion resistance.

Good appearance-translucent, color stable

Good patient acceptance-nonirritating & odorless

Ease of adding to or repairing

Compatibility with provisional luting cements

Currently available materials vs ideal

The ideal provisional material is not yet been developed.

The major problem still to be solved is dimensional change during polymerization which cause marginal discrepancy

In addition the resins currently used are exothermic & not entirely bio-compatible.

Long term provisionalization for FPD

The interim restoration is often used as a guide to achieve optimum esthetics in the definitive restoration.

An accurate interim restoration is a practical way of obtaining specific feedback for the design of a definitive restoration

I’m confused, How do we make one of these enforced interims if it requires a model of the prepared teeth?

In cases where long-term provisionalization is required,
this is the plan:

1. Teeth are prepared.

2. An impression is taken of the preps (Can be a digital
scan).

3. A direct interim is fabricated in the mouth using
conventional method.

4. A cast is fabricated in the lab, using the fiber of your
choice. The FRC interim is then fabricated.

5. The patient returns and has the FRC interim seated.

6. Usually, the patient will wear the first interim for
around a week, and the long-term interim for up to 6
months or beyond.

BioTemps®

Introduced by Glidewell® Dental Labs over 30 years ago.

These interims are fabricated with CAD/CAM technology.

Fabricated from a PMMA polymer.

Has a fast (3-4 day) turn around.

Can be made prior to preparation appointment on a digital model with virtual preps

PVS impression taken to fabricate the definitive FPD for fabrication of definitive FPD [Can also be digital].

Pop up veneer

temporary, removable cosmetic dental appliance that
snaps over existing teeth to improve their appearance.

They are designed to hide imperfections like gaps, chips, and stains, providing a non-invasive, temporary alternative to traditional veneers

some brands use a specific type of polyethylene for their high- quality veneers.

These plastic veneers are not as strong or long-lasting as traditional porcelain veneers and can be prone to wear and tear.

important info concerning temporary cements:

The choice of temporary cement is made by knowing what cement will be used for the definitive restoration.

1. Zinc oxide and eugenol [Tempbond®] cement for FPD’s to be luted [FMC/PFM/Zirconia--RMGI cements-- FujiCem®]

2. Zinc oxide without eugenol [Tempbond NE®] for FPD’s that will use a bonded cement [ACC: Lithium disilicate/Leucite reinforced --Nexis 3®]

You must avoid eugenol when using bonded cements as the eugenol will interfere with resin polymerization

Zinc oxide eugenol cement-

easy removal of the restoration which enables reuse of the restorations.

acceptable sealing properties, has obtundent effect on the pulp.

ZOE cements which contain eugenol are a concern when resin luting agents are to be used as these reduce the tensile bond strength of the resin cements by acting as plasticizer

If there is residual eugenol remaining after setting, inhibits the setting reaction of acrylic resins by inhibiting free radical polymerization in the resins used for provisional restorations and softens acrylic resins with a decrease in physical properties.

The residual eugenol does not allow new acrylic to be added in a reline of the provisional restoration.

In practice all traces of the provisional cement should be thoroughly be removed before using resin luting cement . scraping the tooth with a hand instrument, usually a scaler or curet;
cleaning the tooth preparation with a prophylaxis cup with a water-pumice paste slurry; and the use of an intraoral sandblaster

summary

Although interim restorations are usually intended for short-term use and then discarded, they can be made to provide pleasing esthetics, adequate support, and good protection for teeth while maintaining periodontal health.

Long term provisionals are a key component in the management of complex cases.

They may be fabricated in the dental office from any of several commercially available materials and by a number of practical methods.

In addition, new materials fabricated in dental labs can provide excellent results.

The success of fixed prosthodontic treatment often depends on the care with which the interim restoration is designed and fabricated.

A 32-year-old patient presents for a provisional crown after
preparation of tooth #9. At the follow-up visit, the patient
reports sensitivity to cold and sweets. Clinical evaluation
reveals an inadequate marginal seal on the provisional crown.
Which biological requirement of Provisionals was most likely
compromised?
A. Occlusal compatibility
B. Pulp protection
C. Maintenance of tooth position
D. Resistance against functional load

B. Pulp protection

A patient with heavy bruxism fractures their provisional
bridge within 3 days. The dentist notes that it was fabricated
using autopolymerizing PMMA resin.
Which approach would have been MOST appropriate for
this patient?
A. Use of a polycarbonate crown shell
B. Fabrication of a fiber-reinforced composite provisional
C. Relining with bis-acryl composite resin
D. Use of cellulose acetate crown forms

B. Fabrication of a fiber-reinforced composite provisional

A provisional FPD is cemented with a zinc oxide eugenol
temporary cement. At the time of definitive cementation with
resin cement for a lithium disilicate crown, the bonding fails.
What was the MOST likely cause?
A. Excessive occlusal load during provisional phase
B. Residual eugenol inhibited resin polymerization
C. The provisional was over-contoured
D. Incorrect shade selection of interim

B. Residual eugenol inhibited resin polymerization