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Biomedical subjects

W L Nixon

Publications and source records attributed to W L Nixon.

4 recordsLinked to original sources

Facial pattern differences in long-faced children and adults.

Vertical facial morphology has traditionally been studied by examining subjects chosen because of open bite/overbite or mandibular plane angle. The underlying skeletal and dental morphology associated with clinical facial appearance of normal and vertically dysplastic children and adults has not been well documented. The purposes of this study were to (1) describe vertical facial morphology in long-, normal-, and short-faced children and long-faced and normal adults, and (2) identify morphologic factors associated with the clinical evaluation of long-faced and normal subjects. Forty-two children, 6 to 12 years old, and forty-two young adults with varied vertical facial types were examined clinically and separated into three vertical classifications: long, normal, or short face. Lateral cephalometric radiographs were obtained in natural head position and seven angular, eighteen linear, and six ratio measurements were made. Descriptive statistics were used to characterize all groups, and intergroup differences were compared using analysis of variance for the three child groups and the t test for the two adult groups. For both long-faced children and adults, anterior total face height, mandibular plane angle, gonial angle, and mandibulopalatal plane angle were significantly greater than normal. Ramus height was not significantly different from normal in the children, but there was a tendency for long-faced adults to have short rami. Excessive dentoalveolar development was evident in long-faced children but not in adults. Factors associated with the clinical identification of vertical dysplastic subjects were identified by a principal component analysis. For each component, a variable highly correlated with that component was selected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Occlusal forces in normal- and long-face adults.

Using both quartz- and foil-based piezo-electric force transducers, occlusal forces during swallow, simulated chewing, and maximum effort were evaluated in 19 long-face and 21 normal individuals. Forces were measured at 2.5 mm and 6.0 mm molar separation. Long-face individuals have significantly less occlusal force during maximum effort, simulated chewing, and swallowing than do individuals with normal vertical facial dimensions. No differences in forces between 2.5- and 6.0-mm jaw separation were observed for either group.

Adult↗