Relationship between anteroposterior cranial vault deformation and mandibular morphology in a pre-Columbian population.

INTRODUCTION: An externally applied force to the cranial vault has been reported to affect the growth of the facial skeleton. However, the effect on the mandible is unclear. The purpose of this study was to investigate the relationship between anteroposterior cranial vault deformation and mandibular morphology. METHODS: The study sample included 44 women's crania with intact faces and bases that were excavated from archaeological sites in the Azapa Valley in northern Chile. The crania were divided into anteroposterior deformation (AP) and undeformed (U) groups according to frontal, parietal, and occipital curvatures. The sizes of the cranial vault, middle face, and mandible were measured with calipers. Lateral cephalograms were taken and analyzed according to a conventional method. RESULTS: Cranial base angle, bizygomatic breadth and upper facial height, bicondylar breadth, anterior breadth, and mandibular body length were significantly larger, and the mandibular angle was significantly smaller, in the AP group than in the U group. CONCLUSIONS: The anteroposteriorly shorter and wider cranial deformation caused by externally applied forces in infancy might affect the bone-remodeling process of the mandibular angle, leading to a smaller mandibular angle in adulthood.

A determination of bite force in northern Japanese children.

The bite force of 2594 school children (1248 males and 1346 females) living in northern Japan was investigated during oral health examinations in May and June 2001, using a new type of occlusal force gauge. The subjects were recruited from a variety of educational institutes and comprised: 73 nursery (3-5 years old), 1019 primary (6-11 years old), 902 junior high (12-14 years old) and 600 high (15-17 years old) school children. The measuring apparatus consisted of a hydraulic pressure gauge, with a bite element encased in a plastic tube. The bite force was measured at the first molar or second primary molar in the children presenting in the permanent and primary dentitions, respectively. The findings revealed significant variations in bite force between children of different ages. The average bite force was 186.2 N in males and 203.4 N in females of nursery school children; 374.4 N in males and 330.5 N in females of primary school children; 514.9 N in males and 448.7 N in females of junior high school children; and 545.3 N in males and 395.2 N in females of high school children. The prevalence of malocclusion in the nursery school children was found to be less than 30 per cent, which contrasted with almost 70 per cent in the high school children.