| Research Abstract |
The research summary was as follows ;
(1) With use of a Selspot system, the protrusive and lateral excursions of nine children with the primary dentition and nine adults with the permanent dentition were measured and compared. It was found that the excursions of the primary dentition can move more horizontally and more forward with small descent compared with the permanent dentition. The underlying reason for these findings may be physiological growth, maturation, and adaptation of the occlusal function.
(2) The aim of this study was to estimate dynamic characteristics of passive and active muscle tensions, tensions in the oblique ligament of the TMJ and condylar forces during simulated midline jaw opening and closing in children. The simplified active tension curve for each muscle was modeled by a trigonometric function Y=A^<**>sin (2pi^<**> B^<**> (t-C) 2), in which A represented the EMG amplitude, B the cycle duration, and C the onset time. Midline jaw opening and closing (maximum int
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erincisal distance 10mm, cycle duration 0.8s), were simulated according to jaw motion data from the same child. During the opening phase, tensions of 3N in the digastric muscle and 7N in the inferior head of lateral pterygoid muscle were necessary to open the jaw 10mm. In all mandibular elevator muscles during the closing phase, passive tensionsless than 3N occurred at the beginning of closing phase. There was no tension in the oblique ligament during function. The condylar force increased up to 7N at the end of jaw opening, decreasing to about 1N during jaw closing.
(3) The purpose of this study was to exactly estimate the volume changes of the proper oral cavity before and after treatment for Angle's Class II malocclusion using a bionator. The cephalometric analyzes revealed a decrease in the ANB angle, an increase in the SNP angle, a lingual inclination of the maxillary central incisor and a labial inclination of the mandibular central incisor after treatment. The dimensional analyzes of the study models showed that the inter-molar width increased while, in contrast, both the overbiteand overjet decreased. The volume of the proper oral cavity was measured by the non-contact three-dimensional measuring system. Both the maxillary part and the mandibular part of the proper oral cavity as well as the total volume of that increased by 20% after treatment. Less
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