Surface Wear and Occlusal Stability of Oral Orthotic Devices: An in vitro Comparison Study of Different Occlusal Combinations.
Abstract: Background: Oral orthotic appliances have been used for decades for the treatment of different temporomandibular disorders (TMDs). These appliances function by creating balanced occlusion that reduces the effects of clenching and grinding. However, surface wear of these appliances may affect the occlusal balance created at the time of the initial treatment initiation and subsequently may... read morerender the appliance ineffective. Data on the surface wear of different acrylic materials used for the fabrication of orthotic appliances are lacking. Hence, more research is required. Aim and Hypothesis: The aim of this study was to measure the amount of wear caused by two occlusal surface materials, porcelain and enamel, on three types of orthotic appliance materials: hard splint bioacryl material (thermo-formable PETG polyethylene terephthalate glycol); Durasoft (hard/soft combination of Thermoplastic polyurethane / Polycarbonate, TPU / PC), and methyl methacrylate resin applied to the surface of splint bioacryl to reinforce the occlusal surface. The surfaces were tested under two simulated clinical situations of clenching and grinding. We hypothesized that porcelain would produce more surface wear on the three different materials when compared to enamel, and that the Durasoft group would exhibit more surface wear compared to the other two groups when opposed by either enamel or porcelain. Materials & Methods: Three groups of orthotic appliance materials were subjected to 10.7kg of force for 2800 bi-directional cycles (grinding test) and 1400 bi-directional cycles (clenching test), in a specifically designed wear simulator. The test was performed with samples immersed in artificial saliva at 37°C. Each group of orthotic materials was divided into two subgroups, which were tested while opposing natural extracted teeth (enamel) or their cloned porcelain crowns. All acrylic discs were scanned before and after the application of force. Baseline scans were compared to follow-up scans with 3D digital inspection software (Quantify: Geomagic Inc., Research Triangle Park, NC) from Geomagic 3D and the amount of volume lost was reported in microns. Results: All three types of orthotic appliance material exhibited a lower root mean square (RMS) when opposing enamel in both clenching (Mean[SD]= 0.17[0.05]) and grinding tests (Mean[SD]= 0.18[0.05]) than when opposing porcelain in both the clenching (Mean[SD]=total 0.21[0.04]) and grinding tests (Mean[SD]=total 0.19[0.05]). The main effect of the opposing occlusal surface material (enamel vs. porcelain) was statistically significant in repeated measures ANOVA for the clenching test (p<0.001), but was not significant in the grinding test (p=0.10). As with clenching, under grinding force, the Durasoft group exhibited the highest mean RMS, while samples in the Splint bioacryl with a surface layer of autopolymerized methyl methacrylate resin group exhibited the lowest mean. The main effect of the orthotic appliance material was statistically significant in repeated measures ANOVA in both clenching and grinding tests (p<0.001). Conclusions: The findings of this study lead us to recommend that clinicians monitor patients who have multiple ceramic crowns closely to overcome any appliance imbalance and/or uneven occlusal contacts. The type of orthotic material used plays an additional role in occlusal stability after the initiation of treatment.
Thesis (M.S.)--Tufts University, 2014.
Submitted to the Dept. of Other.
Advisor: Tofool Alghanem.
Committee: Ala Ali, George Maloney, Leopoldo Correa, and Matthew Finkelman.
Keyword: Dentistry.read less