Cephalometric assessment of maxillary length in Serbian children with skeletal class III.

BACKGROUND/AIM: Malocclusion of skeletal class III is a complex irregularity of sagittal inter-jaw relationship, which is due to irregularities of sagittal position of one or both of the jaw bones, which is often associated with disproportionate ratio of their length. The aim of this study was to determine whether the length of the jaw of children with skeletal class III in the period of mixed dentition was changed. METHODS: Fifty children with skeletal class III and the same number of those with skeletal class I, of both sexes, have been selected on the basis of cephalometric analysis of profile tele-x-ray of the head. All the children aged 6-12 had mixed dentition, and were divided according to sex and age into three subgroups within each group. The length of maxilla, mandible and cranial base were measured. Proportions among the lengths measured within each group were found and difference significance in the measured lengths and their proportions among groups and subgroups were evaluated. RESULTS: The children with skeletal class III, compared with the findings in the control group, had significantly lower values of maxillary length, total maxillary length, as well as lower values of their lengths in proportion to lengths of the front or the total length of cranial base and in proportion to mandibular lengths (p < 0.05). Among the patients of different sexes, both in the test and the control group, a significant difference in the values of the measured lengths was found. CONCLUSION: The children with skeletal class III have significantly shorter maxilla than those with skeletal class I.

[Analysis of variation of sagittal position of the jaw bones in skeletal Class III malocclusion].

BACKGROUND/AIM: Skeletal Class III malocclusion is a discrepancy in the sagittal jaw relationship, due to imbalances in their development and/or position, resulting in the dominant appearance of the lower jaw in facial profile. The aim of this study was to determine variations in the sagittal position of the jaw bones to the cranial base in subjects with skeletal Class III, for the earliest possible diagnosis of malocclusion. METHODS: Fifty children and as many adults with skeletal Class III, both sexes, were examined and selected, based on the findings of sagittal interjaw relationship (ANB) < or = 0 degrees from the cephalometric analysis of tele-x-ray profile head shots. The subjects were grouped according to age. The first group consisted of children aged 6-12 years, and another group, of adults aged 18-26 years. We measured the angles of maxillary prognathism (SNA), mandibular prognathism (SNB) and ANB. Based on these results, within the respective groups subclassification into the subgroups was done, among which a significant difference measured values was evaluated. In both groups a significant correlation of the determined values was evaluated. RESULTS: An average SNA angle ranged 77.36 +/- 3.58 in children and 77.32 +/- 4.88 in adults, while an average SNB angle was 79.46 +/- 3.91 in the group of children and 81.12 +/- 3.76 in adults. An average ANB angle was -2.10 +/- 2.07 in children, and -4.00 +/- 2.34 in adults. In both groups, a significant correlation between the measured values and a significant difference in the values of all the measured parameters were found between patients from different subgroups (p < 0.01). CONCLUSION: The most common morphological variation of sagittal position of the upper jaw is its retrognatism, which is equally present in both children and adults. Sagittal position of the lower jaw in most of the adults was prognathic, while mandible prognathism in the children was less present.

[Size of lower jaw as an early indicator of skeletal class III development].

BACKGROUND/AIM: Malocclusion of skeletal class III is a complex abnormality, with a characteristic sagital position of the lower jaw in front of the upper one. A higher level of prognatism of the lower jaw in relation to the upper one can be the consequence of its excessive length. The aim of this study was to find the differences in the length of the lower jaw in the children with skeletal class III and the children with normal sagital interjaw relation (skeletal class I) in the period of mixed dentition. METHODS: After clinical and x-ray diagnostics, profile tele-x-rays of the head were analyzed in 60 examinees with mixed dentition, aged from 6 to 12 years. The examinees were divided into two groups: group 1--the children with skeletal class III and group 2--the children with skeletal class I. The length of the lower jaw, upper jaw and cranial base were measured. The proportional relations between the lengths measured within each group were established and the level of difference in the lengths measured and their proportions between the groups were estimated. RESULTS: No significant difference between the groups was found in the body length, ramus and the total length of the lower jaw. Proportional relation between the body length and the length of the lower jaw ramus and proportional relation between the forward cranial base and the lower jaw body were not significantly different. A significant difference was found in proportional relations of the total length of the lower jaw with the total lengths of cranial base and the upper jaw and proportional relation of the length of the lower and upper jaw body. CONCLUSION: Of all the analyzed parameters, the following were selected as the early indicators of the development of skeletal class III on the lower jaw: greater total length of the lower jaw, proportional to the total lengths of cranial base and theupper jaw, as well as greater length of the lower jaw body, proportional to the length of the upper jaw body.