Effect of Class II camouflage treatment on anterior arch length ratio and canine relationship.

INTRODUCTION: To evaluate the influence of compensatory tipping of maxillary and mandibular incisors on the anterior arch length ratio and canine relationship in skeletal Class II malocclusion. METHODS: The study was based on posttreatment lateral head films and dental casts of 88 patients. The sample was divided into a Class II malocclusion group (32 patients; ANB >/=5 degrees and mean [+/- standard deviation] age, 20.82 +/- 7.67 years) and a Class I malocclusion group (56 patients; 1 degrees </= ANB </= 2.5 degrees and mean [+/- standard deviation] age, 19.20 +/- 5.04 years). Measurements obtained for anterior arch length and width, Bolton discrepancy, canine relationship, growth pattern, and incisor position were compared between the groups. The canine relationship was correlated with dental and skeletal variables (P <0.05). RESULTS: The mean ANB angles were 6.21 degrees and 1.78 degrees for the Class II and Class I malocclusion groups, respectively. The skeletal Class II group presented significantly larger mandibular anterior arch length, producing an unbalanced anterior arch length ratio. The canine relationship was more displaced toward Class II in this group. Anterior arch length ratio was the most influential variable in the canine relationship. The mandibular incisors had a higher compensation degree than the maxillary incisors. The groups were similar regarding overjet, overbite, and growth pattern. CONCLUSIONS: Class II malocclusion camouflage treatment with excessive proclination of the mandibular incisors was associated with an increase in mandibular arch length, negatively influencing the anterior arch length ratio and the final canine relationship. Mandibular anterior arch length reduction by interproximal stripping may be necessary in moderate to severe skeletal Class II malocclusion orthodontic treatment.