AbstractThe aim of this research was to compare three methods to evaluate the availability of existent space in the mandible posterior segment; the methods are the Merrifield’s (1986), Ricketts’ (1976) and Richardson’s (1992). Sixty 60 teleradiographs in lateral pattern, from head, belonging to 60 Brazilian leucoderm subjects were evaluated. The age range from 9 to 19 years, all having a mal-occlusion of Class II, division 1, equally separated as for the gender (being 30 of male gender and 30 of female gender). It was concluded: Evidence of growing in the mandible arch posterior segment in the age range studied, with mean values of 10,21 mm for the Merrifield, 11,21 mm for the Richardson and 17,84 mm for the Ricketts methods. We have concluded that irrespective of the evaluated method, it was verified that the female gender has a more precocious growing (12,17 mm) as compared to the male gender (8,81 mm), in the ages 9 to 12. In the correlation between the employed methods, there was no a statistical difference among themselves by the t test, in the level of 1% (p £ 0,01).
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