Surface Hardness of Different Light-activated and Autocure Resins for Occlusal Splints

Objectives: The aim of study was to investigate the differences between light curing and autocuring of resins for occlusal Splints regarding their surface hardness. Methods: Surface hardness measurements were carried out using a calibrated Vickers indenter. The following light curing resins were used: Acrylight, Triad TranSheet (Colourless/Pink), and Primosplint. This resins were cured using the curing ovens Targis Power (400-500nm) and Kulzer Unilux AC (320-400nm) for 10 and 15 minutes. Furthermore, the autocuring resin Palapress was used. Three different types of samples were prepared. Sample type A: Plates (10x10x3mm) were fabricated of all resins (n=5 per group). Per plate 5 surface hardness measurements were carried out. Sample type B: A total of 70 cylinders (10x6mm) were produced only with light curing resins using closed-end non-translucent pipes. After polymerisation the resin cylinders were grounded flat. Sample type C: Occlusal splints (n=5 splints per group) of all five resins were produced in an articulator (SAM). From each splint 3 cubes (10x10x10mm) were cut out and the hardness was measured from exterior to interior per 1mm. Data were statistically analysed using one-way ANOVA with Scheffé test. Results: Sample types A and C: Surface hardness of autocuring resin Palapress was significantly (p<0.05) lower than that of all light curing resins except Acrylight. The hardness values for Triad TranSheet Pink and Triad TranSheet Colourless were significantly higher (p<0.05) than that of all other resins. Acrylight featured the lowest hardness values (p<0.05). Sample type B: The highest surface hardness of all light curing resins was observed for TranSheet Pink (p<0.05) and Acrylight exhibited the lowest hardness values (p<0.05). Conclusion: Concerning the surface hardness, most light cured resins exhibited significantly greater surface hardness values than the autocuring resin, suggesting that these materials can be an alternative to autocure resins for making of occlusal splints.