Profile changes in orthodontic patients following mandibular advancement surgery

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Tsang, Susan
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Purpose: To define initial hard and soft tissue convexity necessary for profiles to consistently improve after mandibular advancement and to assess if pre-surgical lower incisor inclination (IMPA) affects profile change. Methods: 20 general public, 20 orthodontists, and 20 oral surgeons used a Likert scale to rate attractiveness of before and after treatment profiles of mandibular advancement patients. Spearman’s correlation tested for relationships between amount of profile change and varying ANB, profile angle and pre-surgical IMPA. Wilcoxon test compared extraction and non-extraction profile changes. Results: There was a tendency for inverse correlations between profile change and profile angle, but was not statistically significant any of the 3 groups. There was a tendency for positive correlations between profile change and ANB, but was considered significant only for orthodontists. Orthodontists, oral surgeons and the general public found profiles consistently improved when profile angles were ≤159º, ≤158º and ≤157º, respectively. Orthodontists and oral surgeons found profiles consistently improved when ANB angles were ≥5.5º and ≥6.5º, respectively. Profile worsening increases 2.6 to 5.0 times when profile angles exceeded thresholds, and 4.5 to 7.9 times when ANB angles were less than thresholds. No difference in IMPA or profile change in extraction and non-extraction groups. Conclusion: Extractions are not predictive of a greater surgical profile change. Pre-treatment profile angles <160º and ANB >6º are necessary for consistent improvements after surgery.
profile angle, mandibular advancement, ANB angle