IADR Abstract Archives
Relationship between occlusal plane and mandibular movement during mastication.
Objectives: Camper plane has been used to determine the imaginary occlusal plane when fabricating new prosthesis, since Camper plane is believed as an important morphological criterion. However, the inclination of the occlusal plane in the natural dentition is not necessarily parallel to the Camper plane. Therefore, it is considered that using only the morphological criterion uniformly would lead some problems for the jaw function. It is preferable to refer not only to morphological criterion but functional factors in determining occlusal planes. The objective of this study is to investigate the relationship between the occlusal plane and masticatory movement.
Methods: Masticatory jaw movement of 4 subjects during gum chewing were measured using the jaw movement tracking device with six degrees of freedom (MMJ-2 Shofu). The reference plane was set at the maxillary occlusal plane (maxillary incisor point and both sides of maxillary first molar). The measurement points were the mandibular incisor point and the central fossa of mandibular first molar on the chewing side. Of the 20 chewing cycles, the first and last 5 cycles were excluded and the middle 10 cycles were selected as analysis target. The closing angles of two measurement points to the occlusal plane were calculated and these angles were statistically compared using Wilcoxon signed rank test.
Results: The closing angle of both measurement points tended to converge within a specific range. Moreover, the angle at the incisal point were steeper than that of the mandibular first molar. These values were 73.6 ± 5.6 and 64.7 ± 10.6 degrees (Mean ± SD), respectively. A statistically significant difference was observed between two closing angles (p<0.05).
Conclusions: These results suggest that masticatory movement could be used as important functional factors when determining the occlusal plane.
Methods: Masticatory jaw movement of 4 subjects during gum chewing were measured using the jaw movement tracking device with six degrees of freedom (MMJ-2 Shofu). The reference plane was set at the maxillary occlusal plane (maxillary incisor point and both sides of maxillary first molar). The measurement points were the mandibular incisor point and the central fossa of mandibular first molar on the chewing side. Of the 20 chewing cycles, the first and last 5 cycles were excluded and the middle 10 cycles were selected as analysis target. The closing angles of two measurement points to the occlusal plane were calculated and these angles were statistically compared using Wilcoxon signed rank test.
Results: The closing angle of both measurement points tended to converge within a specific range. Moreover, the angle at the incisal point were steeper than that of the mandibular first molar. These values were 73.6 ± 5.6 and 64.7 ± 10.6 degrees (Mean ± SD), respectively. A statistically significant difference was observed between two closing angles (p<0.05).
Conclusions: These results suggest that masticatory movement could be used as important functional factors when determining the occlusal plane.