Evaluation of marginal and internal gaps in single and three-unit metal frameworks made by micro-stereolithography

Abstract

PURPOSE. The purpose of this study is to compare single and three-unit metal frameworks that are produced by micro-stereolithography. MATERIALS AND METHODS. Silicone impressions of a selected molar and a premolar were used to make master abutments that were scanned into a stereolithography file. The file was processed with computer aided design software to create single and three-unit designs from which resin frameworks were created using micro-stereolithography. These resin frameworks were subjected to investment, burnout, and casting to fabricate single and three-unit metal ones that were measured under a digital microscope by using the silicone replica technique. The measurements were verified by means of the Mann Whitney U test (alpha=.05). RESULTS. The marginal gap was 101.9 +/- 53.4 mu m for SM group and 104.3 +/- 62.9 mu m for TUM group. The measurement of non-pontics in a single metal framework was 93.6 +/- 43.9 mu m, and that of non-pontics in a three-unit metal framework was 64.9 +/- 46.5 mu m. The dimension of pontics in a single metal framework was 110.2 +/- 61.4 mu m, and that of pontics in a three-unit metal framework was 143.7 +/- 51.8 mu m. CONCLUSION. The marginal gap was smaller for the single metal framework than for the three-unit one, which requires further improvement before it can be used for clinical purposes.