Peculiarities of the shape and size of the mandible and the lower dentition with taking into account gender and craniotype

Abstract

The aim of the study: establishment of actual intravital craniometric characteristics of the shape and dimensions of the mandible and lower dentition of an adult person depending on gender and craniotype. Research materials and methods: the work used dry bone preparations of whole or fragmented human skulls of both sexes in the amount of 39 units, from the collection of the Department of Human Anatomy of the Kharkiv National Medical University, and the results of CT studies of the head of adult people without existing bone tissue pathologies, totaling 85 observations. The basis of establishing a craniotype is the principle of calculating the general facial or facial index, which allows classifying anatomical objects according to the shape of the head structure. Research results: the straight length of the mandible in adult leptoprosops males is from 88.5 mm to 102.4 mm, for women - from 86.3 mm to 100.7 mm; in mesoprosops men, this parameter gradually decreases to the level - from 81.3 mm to 95.7 mm, in women - from 80.7 mm to 94.9 mm; in euryprosops, the index is the smallest and ranges from 79.7 mm to 91.5 mm in males and from 78.5 mm to 90.8 mm in females. The opposite trend with significant ranges of variation is established for the angular width of the bone. Thus, in male leptoprosops, this parameter was determined from 84.6 mm to 97.5 mm, in female representatives - from 83.6 mm to 96.3 mm; in mesoprosops men, it increased from 89.1 mm to 105.3 mm, in women - from 87.9 mm to 103.1 mm; in euryprosops, regardless of sex, it reached its peak values, from 94.5 mm to 116.1 mm and from 92.7 mm to 114.1 mm, respectively. The height of the mandibular body also showed a certain dependence on the type of skull structure, in leptoprosops men it tended to the highest values ​​and was fixed at the level from 29.1 mm to 38.9 mm, as well as in women - from 27.5 mm to 37.8 mm; at the same time, in mesoprosops men, the size decreased from 25.9 mm to 36.3 mm, in women, in turn, from 24.6 mm to 35.1 mm; in euryprosops men, this parameter ranged from 22.3 mm to 33.1 mm, and next to women - from 21.9 mm to 31.9 mm, it was at the level of the lowest indicators. When analyzing such a complex and multidirectional parameter as the arch of the mandible, it was also possible to obtain a characteristic of its dependence on the type of structure of the facial department of the skull. It was established that the range with the smallest values ​​of the length of the arc is characteristic of leptoprosops, ranging from 135.8 mm to 149.4 mm in males and from 133.5 mm to 147.3 mm in females; average indices are characteristic of men - from 139.1 mm to 154.6 mm and women - from 136.4 mm to 151.2 mm with a mesoprosopic craniotype; in euryprosops of both sexes, the index tends to the greatest values ​​at the level of 141.2 mm to 158.3 mm and from 139.7 mm to 155.7 mm, respectively. Conclusions: the main craniometric parameters of the mandible are significantly dependent on the type of structure of the facial department of the skull. Thus, the leptoprosopic craniotype is characterized by maximum values ​​of longitudinal and height dimensions with minimal indicators of width and arc length. Mesoprosops are characterized by the definition of intermediate, averaged values ​​equidistant from marginal, terminal forms. In representatives with the euryprosopic type of skull structure, a significant decrease in the length and height of the jaw with a significant increase, up to the maximum values, width and length of the arch was observed. At the same time, unlike leptoprosops, which had a shortened and pointed arch, in euryprosops, the arch tended to be smoothed and lengthened. The assessment by sex leads to the fact that all sizes of the lower jaw predominate in men, but, nevertheless, a certain number of differences in indicators were within the limits of statistical error, which does not allow making absolute conclusions in this matter