Effects of treatment changes in the mandibular incisor inclination on the stability of the posttreatment results in Class II, dicision 1 malocclusions.

S.E. Bishara, J.R. Jacobsen

Hellenic Orthodontic Review 2000;3:21-33.

The aim of this study was to evaluate the posttreatment changes in patients with a Class II, division 1 malocclusion treated either with an extraction or a nonextraction approach. In each of these two groups, the sample was retrospectively subgrouped according to the treatment changes in the mandibular incisor inclination. These subgroups were compared to determine if differences in the posttreatment changes were present.

A total of 79 patients were treated for their Class II, division I malocclusion. Thirty-seven patients (17 males and 20 females) were treated with four first premolar extractions and forty-two patients (20 males and 22 females) were treated without extractions. A total of 30 cephalometric and 38 dental arch measurements were obtained.

In both the extraction and nonextraction groups, all individuals were rank ordered according to the treatment changes in the LI:MP angle. The sample in each of the two treatment groups were then divided into 3 subgroups: (a) lower incisors moved lingually during treatment (decrease), (b) lower incisors moved labially during treatment (increase), and (c) an intermediate group that experienced little or no change during treatment and was eliminated for the purpose of the present study.

The Analysis of Variance was used to compare the various subgroups. The present findings indicated that in “well treated” cases, the movement of the lower incisors relative to the mandibular plane whether lingually or labially during treatment did not significantly (p>0.05) influence the direction or magnitude of the dental arch posttreatment changes in the pextraction and nonextraction groups.

Request for reprints: Dr. Samir E. Bishara, Professor, Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, Iowa 52242, U.S.A.