O tratamento da Classe III: revis？o sistemática - Parte I. Magnitude, dire？？o e dura？？o das for？as na protra？？o maxilar

introduction: for the treatment of class iii during growth, maxillary protraction therapy is the most reported in the literature. during the treatment is required special attention to the mechanics used to fix the problem. aim: to synthesize informations about the magnitude, direction and time of daily application of forces, through a systematic review. methods: studies were identified from an electronic search on medline database - entrez pubmed (178 articles) and bireme (550 articles), from january 1983 until december 2008. after rigorous process of inclusion and exclusion 56 primary studies were selected and subjected to a second selection process, remaining 39 articles. it was calculated the average and standard deviation, and the minimum and maximum values for magnitude, direction and usage hours of the maxillary protraction forces. results and conclusion: the mean magnitude, direction and duration of the forces of maxillary protraction were, respectively: 447.8 grams, 27.5 degrees of inclination in relation to the occlusal plane and 15.2 hours per day.