Comparison of Marginal and Internal Defects of Indirect Inlay Patterns Fabricated Using Additive Manufacturing and Traditional Methods - An Ex Vivo Study.

Abstract

This study aimed at exploring clinical translation of additive manufacturing methods for fabrication of inlay restorations. On a selected human premolar tooth sample an inlay cavity was prepared. A silicon impression of the tooth was recorded and ten die-casts were poured. Ten inlay wax patterns were fabricated using traditional method. An optical impression of the tooth model was obtained and 20 computeraided inlay designs were fabricated and optimised for additive manufacturing. Ten models were fabricated by micro-stereolithography and the other ten were fabricated using selective laser sintering. 30 inlay patterns were cast into cobalt chromium metal inlays. For 30 metal inlays, marginal and internal gaps were measured using a silicone-replica-technique, observed under a scanning electron microscope. The measured internal gaps were: Internal-gaps in Conventional lost wax technique (138 ± 8.7), micro-stereolithography (200 ± 7.4) and selective laser sintering (203 ± 11.8). The marginal gaps were: Conventional lost wax technique (162.12 ± 6.8), micro-stereolithography (198 ± 10.3) and scanning laser sintering (203 ± 6.6) Conclusions: The marginal gap and internal gap of a conventional lost wax technique were significantly improved compared with microstereolithography and selective laser sintering (P⟨0.05). However, according to previous criteria for maximum allowable discrepancy (100 - 200 μm) microstereolithography may represent a potential future alternative for indirect inlay fabrication.