Typical features of morphometric parameters of the mandible in adults
<b>Objective:</b> to develop a classification of mandibular forms and to study typical features of the morphometric characteristics of this bone in adults. <b>Materials and methods.</b> The study was conducted on 150 lower jaws of adults. To determine the shape of the lower jaw, four morphometric parameters were measured: angular width, projection length from the corners, branch height, smallest branch width, and three morphometric indexes were introduced: 1 - the long-length longitudinal index of the lower jaw; 2 - longitude latitudinal index of the body of the lower jaw; 3 - latitudinal-altitude index of the branches of the lower jaw. According to these indices, 9 groups of jaws with different shapes were identified. In these groups, the values of 35 morphometric parameters of the body and branches of the lower jaw were studied. <b>Results.</b> It was found that statistically significant differences (p <0.05) between the groups of jaws, determined by the value of the altitude-longitude index of the lower jaw and the longitude-latitude index of the body of the lower jaw, exist between the same morphometric parameters: angular width, projection length from the corners and chin angle , and most of the morphometric parameters of the body and branches of the lower jaw do not statistically significantly differ between the extreme forms (dolicho- and brachi, lepto- and eurimandibular). There are statistically significant differences between the jaw groups, systematized by the latitude-altitude index of the branch of the lower jaw (p <0.05) for most of the studied indicators of the branch of the lower jaw: branch height, smallest branch width, notch width, notch angle, base of the coronoid process , the base of the condylar process, the distance from the front edge of the lower jaw branch to the opening of the lower jaw, the distance from the notch of the lower jaw to the opening of the lower jaw, the distance from the angle of the lower jaw to the opening of the lower jaw. It has been proved that in the lower jaws with a hypsiramimandibular form, the values of the smallest branch width, the base length of the coronoid and condylar processes, as well as the distance from the front edge of the branch to the opening of the lower jaw are significantly smaller, however, the values of the branch height, notch angle, notch width, notch distance the angle of the lower jaw to its opening is larger compared to the platyramimandibular form (p˂0.05). <b>Conclusion.</b> The greatest number of differences in the value of morphometric parameters is observed during the systematization of the lower jaw according to the shape of its branch. This can be explained by the fact that it is under the direct influence of the masticatory muscles, performing not only supporting, protective, but also motor function.