The surface roughness analysis of the titanium casting founding by a new titanium casting investment material / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the surface roughness property of the titanium castings cast in a new investment for titanium casting.</p><p><b>METHODS</b>Six wax patterns (20 mm × 20 mm × 0.5 mm) were invested using two investments: three in a new titanium investment material and three in the control material (Rematitan Plus). Six titanium specimens were obtained by conventional casting. After casting, surface roughness of the specimens were evaluated with a surface profilometer.</p><p><b>RESULTS</b>The surface roughness of the specimens cast in new titanium investment material was (1.72 ± 0.08) µm, which was much smaller than that from Rematitan Plus [(1.91 ± 0.15) µm, P < 0.05].</p><p><b>CONCLUSIONS</b>The surfaces of titanium cast using these two investment materials are both smooth enough to fulfill the demand of the titanium precision-casting for prosthodontic clinical use.</p>

Relationship between occlusal plane and masticatory path in youth with individual normal occlusion / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the characteristics of and relationship between occlusal plane and masticatory path in young adults with individual normal occlusion, and to provide clinical implications on both morphological and functional reference of occlusal plane location.</p><p><b>METHODS</b>Forty-three young adults with individual normal occlusion were included. Lateral projections of cephalometric radiographs were taken. The parameters of anatomical landmarks were analyzed. The BioEGN mandibular kinesiography analyzer was used to record the path of incisal edge of mandibular central incisor movement during mastication. The Pearson's linear correlation analysis was performed to analyze the relationship of inclination of occlusal plane and data mentioned above with SPSS13.0 software.</p><p><b>RESULTS</b>The inclination of occlusal plane (the angle between occlusal plane and Camper's line OP-CP) was (2.1 ± 3.8)° in youth with normal occlusion. Means of maximal distances of 3-dimensional masticatory mandibular movement paths were as follow: the vertical length was (20.22 ± 4.28) mm, the anterior-posterior width was (11.42 ± 2.45) mm, and the lateral width was (8.62 ± 1.52) mm. The inclination of occlusal plane was negatively correlated to the lateral width of masticatory path in frontal plane (r = -0.39, P < 0.05). Occlusal plane was approximately vertical to the opening and closing path in the vicinity of intercuspal position during mastication. The inclination of occlusal plane was positively related to occlusal plane-closing angles in the upper segments of closing path during mastication (P < 0.05). Masticatory axis angle was (66.50 ± 7.98)° with no significant correlation to the inclination of occlusal plane (P > 0.05).</p><p><b>CONCLUSIONS</b>These results suggest that the sagittal inclination of occlusal plane can influence 3-dimensional morphology of masticatory path.The inclination of occlusal plane has a guiding effect on masticatory movement in the upper segments of closing path.</p>