Intra-arch widths: a meta-analysis.

OBJECTIVE: To determine and compare the mean values of various intra-arch distances in Class I, Class II division 1 and Class II division 2 patients. MATERIALS AND METHODS: The search engines PubMed, Embrace and Cochrane were employed to select articles for further study, and the sample thereby selected comprised adult subjects with full permanent dentition, without missing teeth, malformations or previous orthodontic treatment. Only subjects from articles published during the last 10 years were included in the study. RESULTS: The search located a total of 628 articles regarding arch form. However, only eight articles were chosen for the study. We observed that: the distance between mandibular canines is smaller in Class I than in Class II division 1; mandibular inter-molar distance is similar in Class I and Class II division 1; maxillary inter-canine distance is similar in Class I, Class II division 2 and Class II division 1; maxillary inter-premolar width is greater in Class I than in Class II division 1; and that maxillary inter-molar width is similar in Class I and Class II division 2. CONCLUSIONS: No statistically significant differences in arch width were found between the different classes analysed (there are only slightly differences between classes), except in the case of mandibular inter-canine width (L3), which was smaller in Class I than in Class II,1, and maxillary inter-premolar width (U4), which was smaller in Class II-I than in Class I