Effects of comprehensive orthodontic treatment with distalization of maxillary molars on the mandibular dentition
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INTRODUCTION: Non-extraction Class II malocclusion treatments often employ the use of maxillary dentition distalization mechanics. The rationale behind these mechanics is to treat the sagittal position of the maxillary dentition to the mandibular dentition. As anchorage loss may occur after distalization of molars, inter-arch mechanics are often used during comprehensive treatment that may manifest in the finish as a more protrusive lower dentition. OBJECTIVE: To evaluate the efficacy of several distalization modalities, used as part of comprehensive orthodontics, by measuring the overall effects on the dentition and soft tissue. MATERIALS AND METHODS: Four different modalities of distalization treatment of Class II malocclusion were compared regarding dental and soft tissue changes: Distal Jet (n=26), Horseshoe Jet (n=26), Pendulum (n=26), and the MGBM (Maino, Giannelly, Bernard, Mura) protocol (n=25). The Horseshoe Jet and MGBM methods use miniscrews supported anchorage while the Distal Jet and pendulum do not. The majority of the pendulum subjects (24 of 26) were prescribed headgear wear. For each of the groups, lateral cephalograms were taken before treatment and after comprehensive treatment. RESULTS: Minimal differences in soft tissue changes between the groups were found; however, significant (p≤0.05) differences in dental changes between groups for lower incisor, upper incisor, and upper first molar sagittal positions were found. Lower incisors showed significant protrusion and proclination for the Distal Jet experimental group (p<0.05). The upper incisor showed the greatest uprighting and retraction (p<0.05) in the pendulum group and the most proclination (p<0.01) in the Horseshoe Jet group. CONCLUSION: Three out of four experimental groups showed some amount of lower incisor protrusion and/or proclination. Bone anchored modalities had reduced side effects on the lower incisors, with the Horseshoe Jet showing less change than Distal Jet (p=0.05) and the MGBM group showing no significant change. The pendulum group had the greatest upper incisor retraction and showed negligible lower incisor proclination with only 1 out of 6 measurements showing significance.