DIỄN TIẾN HÌNH THÁI KHỚP CẮN TỪ BỘ RĂNG SỮA ĐẾN HỖN HỢP VÀ VĨNH VIỄN Ở NHÓM CÓ TƯƠNG QUAN MẶT PHẲNG TẬN CÙNG RĂNG CỐI SỮA THỨ HAI DẠNG BẬC XUỐNG GẦN

Abstract

Background: There are three types of the final step in the deciduous dentition: flush, mesial, and distal type. Although the flush type is considered to be one of the factors of "ideal occlusion" of deciduous dentition, it is likely (20-50%) to become abnormal class II molar relationship in permanent dentition. Therefore, many authors believe that the mesial step type should be regarded as the ideal type of deciduous teeth, rather than the flush type because the normal class I molar relationship conversion rate of this group is the highest among the three types above. In Vietnam, no studies have been done to evaluate the progression of occlusal morphology of the mesial step group during the whole process of dentition. Therefore, we conducted a study "progress of occlusal morphology from deciduous to mixed and permanent dentition in the mesial step group". From the findings, appropriate prevention and intervention plans can be made to help children achieve normal occlusal in the future. Objectives: To evalute the progression of occlusal morphology of the mesial step group during the whole process of dentition from the deciduous to mixed and permanent dentition. Materials and methods: Longitudinal study on 79 mesial step of deciduous dentition. To evalute the changes of that group from deciduous to mixed and pernament dentition. Results: In 79 mesial step relationships, when transitioning from the deciduous to the mixed dentition, the conversion rate was 49% and 51% respectively compared with class I and class II 50% molar relationship. When change from the mixed dentition to the permanent stage, 85% of the class I molar relationship will maintain this correlation, the rest will be converted into class III and class II 50% molar. For the class II 50% molar group in the mixed dentition, when switching to the permanent stage, 80% will be converted into class I molar, and the rest will keep a class II 50% molar correlation. When change from the deciduous dentition to the permanent stage, there are 82% will be converted into normal class I molar, the rest will be converted into class II and class III molar relationship. Conclusion: During the development from deciduous teeth to permanent teeth, the mesial step final plane will be converted to normal class I molar correlation with a very high rate (82%).