In vitro wear pattern of occlusal splints in bruxist patients

PURPOSE: The aim of this in vitro study was to evaluate the effect of different restorative materials for molar and premolar area in the wear of occlusal bite worn by bruxist patients. The first null hypothesis is that there is no difference in bite wear due to the different types of materials used for the restorations. The second hypothesis is that there is no difference in bite wear between the molar area and the premolar area. METHODS: intraoral scans of a patient, obtained with Cerec Omnicam, are selected to obtain 3D printed models (SolFlex 170, Voco Gmbh) of the lower and upper jaw. On the upper jaw, an occlusal bite with V-Splint is obtained. On the lower jaw, posterior teeth are divided in different groups based on the restorative material employed. Were selected for this in vitro study: E-Max CAD (Ivoclar, Shaan, Luxembourg), Grandio Blocs (Voco GmbH, Cuxhaven, Germany), Vita Enamic (VITA Zanhfabrik, Bad Sackingen, Germany), Admira Fusion (VOCO GmbH, Cuxhaven, Germany). Overlays are created and luted over lower printed models (V-Print Model, Voco). After 24h, samples are submitted to fatigue test with a chewing simulator (CS4.4, Mechatronik, Germany) and subjected to 3 sessions of 500,000 cycles of mechanical fatigue in a dual-axis masticatory simulator (Willytec Kausimulator, Willytec, Munich, Germany). A force of 8 kg is applied with a semi-circular movement with 4mm in horizontal slide, 16mm/s. Scans of the occlusal part of the bites are performed (LAS-20, SD-Mechatronic) in order to calculate the occlusal wear in µm3. RESULTS: Statistical analysis revealed a not significant influence of the factor “material”, while the factor “area” and their interactions showed difference between the test materials in terms of wear rate. Statistical analysis revealed a not significant influence of the factor “material” (p = 0.8271), of the factor “area” (p = 0.0480) and their interactions (p = 0.0303). After the results of the two-way Anova Test, a post hoc showed that the molar region of the OS highlighted the higher volumetric wear rate. CONCLUSION: within the limits of this study the following conclusions were drawn: there was no evidence that the OS wear pattern was different respect the different restorative materials used to antagonists restorations. A statistically significant correlation was found between the increase in wear of the molar area of the OS compared with the premolar one.