INTRODUCTION:
The significance of the provisional (treatment) restoration among the procedures required for successful completion of a fixed partial denture is often overlooked. Perhaps the inaccurate assignment of the term “temporary” to the interim restoration has generated the misconception that, eventual placement of the permanent restoration will immediately and miraculously remedy the detrimental effects of a poorly conceived and fabricated transitional restoration. The treatment with provisional restorations is an integral part of restorative treatment procedures with fixed prosthetic restorations i.e. crowns and bridges.
Provisional has to fulfill important functions within the timeframe between preparation of a tooth and until fitting respectively luting of the final fixed metal or ceramic restoration. A well-made provisional fixed partial denture should provide a preview of the future prosthesis and enhance the health of the abutments and periodontium. The provisional restoration is often intended for diagnostic and therapeutic purposes, being a test structure where all the necessary functional, occlusal, and esthetic adjustments can be carried out to optimize incorporation of the definitive prosthesis. This is subsequently made on the basis of the information recorded from the provisional restoration, whose occlusal surface is made of resin and can be shaped and carved in accordance with the patient’s stomatognathic dynamics.
AIMS & OBJECTIVES:
The objectives of this study were
To find out the Flexural strength, compressive strength,microhardness,colour
stability and polymerization shrinkage of three provisional materials namely,
1. REVOTEC LC,
2. PROTEMP 4,
3. TEMSPAN.
This study was done with following aims and objectives:
1. To evaluate the flexural strength values of three different provisional composite restorative materials.
2. To evaluate the compressive strength of three different provisional composite restorative materials.
3. To evaluate the color stability of three different provisional composite restorative materials at different immersion periods in a standardized coffee solution.
4. To evaluate the change in micro hardness of three different provisional composite restorative materials at different immersion periods.
5. To evaluate the polymerization shrinkage of three different provisional composite restorative materials at different time intervals.
MATERIALS USED FOR THE STUDY:
1. TEMPSPAN - is a dual cure system consisting of Bisphenol-A diethoxy
methacrylate based material.
2. PROTEMP 4 -is a chemically cured 2 component system, consisting of Bis – GMA based material.
3. REVOTEK LC -is a light cured single component composite resin consisting of Urethane dimethacrylate resins (UDMA).
4. Coffee powder (Nescafe, New Delhi, India),
5. Polishing – Tungsten Carbide, Pumice and diamond polishing paste,
6. Artificial saliva,
7. Distilled water.
Instruments:
1. Stainless steel mold used to prepare the specimens.
2. Standard weight – in Kilograms- 2.5 Kg weight is used.
Equipments:
1. Universal testing machine (fig 13): Manufactured by Llyods company, England (Model INSTRON 3382) to test the Flexural strength and compressive strength samples.
2. Knoops hardness tester (fig 17): Model 420 MVD Walpert Wilson Instrument, to test the samples for microhardness.
3. Spectrophotometer (fig 19) : Minolta CM 3600d-Japan ,to test the samples for color analysis.
4. Coordinate measuring machine (fig 21) : To test the specimens for Polymerisation shrinkage.
SUMMARY AND CONCLUSION:
The aim of the study was to compare the properties of three composite provisional crown and bridge materials. Samples from provisional materials were prepared to check five different properties namely
1. Flexural strength,
2. Compressive strength,
3. Microhardness,
4. Colour stability and,
5. Polymerization shrinkage.
A standardized procedure was adopted for the preparation of test specimens. According to specimen size, 3 groups were categorized namely:
SPECIMEN A- Used for calculating flexural and compressive strength.
Specimen A size was standardized with 25mm x 2mm x 2mm (American national Standards Institute / American Dental Association specification no 27).
SPECIMEN B- Used for calculating colour stability and microhardness.
Specimen B size was standardized with 20mm diameter cicles, 2mm thickness.
SPECIMEN C- Used for calculating polymerization shrinkage.
Specimen C were standardized with stainless steel plate 2mm in thickness.
Six circles of 20mm diameter were machined to form the mold space. V shaped notches with a 2mm diameter at open end of V were made at 4 corners of the circles to help us in measuring the shrinkage in 2 dimensions.
According to types of materials used, it was categorized into 3 groups namely,
Group 1 - Light cure material – REVOTEK LC,
Group 2 - Self cure material – PROTEMP 4,
Group 3 - Dual cure material – TEMPSPAN.
10 samples from each of the 3 groups were subjected to five different property testings. From the results obtained,
1) Group 2 - Self cure material – PROTEMP 4 has more flexural strength.
2) Group 2 - Self cure material – PROTEMP 4 has more compressive strength.
3) Group 2 - Self cure material – PROTEMP 4 has more microharness.
4) Group 1 - Light cure material – Revotek LC is more colour stable.
5) Group 2 - Self cure material – PROTEMP 4 exhibits least shrinkage.
1. When provisional restoration is to be given in the esthetic region then urethane dimethacrylate based material (Revotek LC) can be used.
2.When the provisional restoration has to be placed for a longer span of time then chemically cured bis-GMA based material (Protemp 4) can be used.
3. If a provisional long span bridge has to be placed then chemically cured Bis-GMA based material (Protemp 4) can be used.
It was inferred from the study that no one material was superior in all five tested parameters. Although these products are made from similar materials, variation in formulation including the cross-linking agents, appear to have resulted in variations in the performance. Further investigation is required to elucidate the nature of product differences and the way in which these materials respond to the oral environment
