INFLUENCE OF DIE SPACER APPLICATION ON MARGINAL ADAPTATION OF INDIRECT TEMPORARY CROWNS FABRICATED USING STONE AND SILICONE MODEL MATERIALS

Purpose: Evaluate and compare the effect of using die spacer on marginal accuracy and fit of indirectly fabricated temporary restorations using silicone model material and stone dies.
Problem statement: Chairside temporary restorations fabricated by the direct method commonly show binding on seating, or short margins or premature contacts after temporary cementation. Temporary restorations are fabricated without spacer which may compromise the fit. Therefore it would be an advantage to provide adequate internal fitting space to optimize marginal adaptation.
Methodology: Master die was typodont .Maxillary first molar was manually prepared as in an actual clinical situation. A vacuu-pressed tooth index was made before preparation to standardize the dimension of the temporary restoration. A total of twenty temporary crowns were fabricated from autopolymerizing Bis-acryl resin material and divided into two groups according to the model material used (n=10) stone (Fuji rock; type IV die stone, GC & Modellsilikon, VOCO GmbH, Cuxhaven, Germany) poured from alginate impressions. Each group was subdivided into two subgroups according to spacer used; with and without spacer (n=5). Two coats (approximately 30 µm) were painted on the dies. All the fabricated temporary restorations were visually examined internally and verified for complete seating on its corresponding die. Seating and fit of each crown were evaluated on the master die and were stored in distilled water overnight till testing took place. Margins were inspected and photographed under magnification of 45X using USB Digital microscope measurements. The generated data was statistically analyzed. The significance level was set at P ≤ 0.05
Results: There was no statistically significant difference between vertical marginal gap distances in the two groups; (79.9+15.0 µm) (66.4+10.0 µm) without spacer and with spacer respectively at P ≤ 0.05
Conclusion & Clinical implications: Despite that the resulted difference in gap is insignificant however painting spacer seems to provide better cement escape vent thus easing fit, also the use of silicone model material offers a practical, speedy and simplified method to conveniently fabricate a good fitting temporary restoration.