Marginal fit of resin and wax pattern materials for casting

Abstract

Introduction: Wax and resin-based pattern materials are known to undergo distortion upon setting that may adversely affect to the accuracy of the final restoration. Objective: To evaluate and compare in vitro, the dimensional accuracy of three resin and the two wax-based inlay pattern materials. Methods: Five pattern materials were evaluated in this study: three resins: a. Duralay (Reliance); b. Pattern Resin LS (GC); c. Paintacryl (Schutz Dental); and two waxes: d. Inlay Wax (Cornings Wax Company); e. Inlay casting wax Hard type, Class 1 (Kerr). Class II inlay preparations were prepared in ten ivorine teeth. A separating agent (Coe-Sep tinfoil substitute - GC) with a film thickness of 5 microns was applied to all of the surfaces of the preparation. Inlay patterns were fabricated directly on each prepared tooth using the five test materials (total of 50 patterns). The tooth and the pattern were held together with a clamp to establish a contact seating force. Measurements were taken at the margin between the tooth and the pattern using an optical microscope (at 50x magnification) coupled with a video micrometer. Six measurements per pattern were taken (2 proximal-buccal, 2 proximal-lingual and 2 proximal-gingival), thus a total of 300 measurements. Results: Mean marginal gap measurements (microns) and standard deviations are presented in the following table. One-way ANOVA was used to analyze the data. DURALAY: Mean 24.3 SD 11.5 GC PATTERN RESIN: Mean 26.4 SD 14.5 PAINTACRYL PATTERN RESIN: Mean 22.7 SD 12.5 CORNING'S INLAY WAX: Mean 23.3 SD 12.9 KERR INLAY WAX: Mean 19.4 SD 11.0 Conclusion: Marginal gap formation between the test materials and the tooth preparation ranged from 15 to 21 microns (taking into account that 5 additional microns were attributed to the separating agent). There was no significant difference in the marginal fit among any of the pattern materials tested in this study, thus all of the test materials are equally acceptable for clinical use.