A Comparison of Clear Aligners and Fixed Appliances in Orthodontic-Surgical Treatment of Non-Extraction Skeletal Class III Malocclusion

This retrospective study assessed the outcomes of combined orthodontic-surgical treatment in skeletal Class III patients by comparing results achieved with clear aligners to those achieved with conventional fixed appliances.

This study involved 24 skeletal Class III malocclusion patients who were treated with non-extraction orthodontic using either fixed appliances or clear aligners (Invisalign), in conjunction with orthognathic surgery. All patients underwent mandibular surgery only. Lateral cephalometric radiographs were obtained and analysed for both groups at three stages: before orthodontic treatment (T0), one week before surgery (T1), and at least eight months after surgery (T2). All the statistical tests were performed in SPSS 30 and power calculations were done in G*Power.

In this pilot study, significant skeletal and dentoalveolar changes occurred in both groups (p < 0.001). Between-group comparisons showed that during presurgical decompensation (T1-T0), fixed appliances produced greater lower incisor proclination (IMPA) (p < 0.05, Cohen's d = -1.13 - 1.27). During postsurgical orthodontics (T2-T1), clear aligners resulted in less lower incisor labial tipping (L1-FH), less upper incisor intrusion (U1-PP), and less lower first molar intrusion (L6-MP) (p < 0.05, d = -1.03 - 1.1). At final follow-up (T2-T0), the clear aligner group continued to show less vertical intrusion of the lower incisor and first molar (L1-MP, L6-MP; p < 0.05, d = 1.11-1.17). After adjusting for genioplasty, clear aligners were associated with superior postsurgical vertical skeletal control, upper lip retraction, and facial convexity (p < 0.05).

Within this pilot study, clear aligners showed signals of greater treatment efficiency, less unwanted labial tipping, and reduced vertical intrusion, whereas fixed appliances showed greater incisor and molar decompensation. These hypothesis-generating findings indicate that treatment individualization by biomechanical needs and patient preferences should be tested in future powered trials.

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