A LONGITUDINAL CEPHALOMETRIC STUDY OF NORMAL CRANIOFACIAL GROWTH OF THE RHESUS MONKEY (MACACA MULATTA) (ANALYSIS, CURVES).

摘要

Serial lateral cephalograms taken at 24 week intervals on 35 captive rhesus monkeys (20 male and 15 female) which had radiopaque bone-markers implanted were traced and digitized using a scheme representing the major components of the craniofacial skeleton and dentition. These normal monkeys ranged in age from 0.5 to 10 years. The bone markers were used for superimposing the serial films objectively to describe morphological change. A cross-sectional set of comparable cephalograms (48 male, 41 female) of monkeys of known age was used to develop age estimation techniques. Statistical methods which account for the covariance structure in the longitudinal data set were implemented and applied to generate average growth curves, confidence bands, and measures of velocity and acceleration for jaw dimensions, linear and angular displacements of the jaws relative to each other and the cranial base, and local remodeling at landmarks on both jaws.;Posterosuperior growth at the maxillary tuberosity accounts for the majority of increments in maxillary length and its anteroinferior repositioning relative to the cranium. Appositional growth along the facial aspect of the maxilla also makes a constant and significant contribution to increases in maxillary size. Posterosuperior growth at the mandibular condyle accounts for most increments in mandibular length. Growth peaks for many of the maxillomandibular variables were found between 3.5 to 4 years of age in the males. Growth peaks in the females were less pronounced. Levels of growth at the condyle and maxillary tuberosity in the females were considerably below the males between 2.5 and 5 years of age. At sites of slow apposition such as supradentale, the activity in females was marginal, whereas that in males was low but significant. Growth at most sites was completed by 7 years in the males and 5 years of age in the females. Both jaws rotated counter-clockwise throughout ontogeny though these angular changes were masked by occlusal plane rotations in the opposite direction. In general these results refine the current picture of craniofacial growth in the rhesus monkey by providing statistically rigorous, quantitative descriptions of growth at a variety of sites, for a continuous range of ages.