Clear aligners were associated with less unwanted tooth movement than conventional fixed appliances during the orthodontic phase after jaw surgery in patients with skeletal Class III malocclusion. The clear-aligner group had less lower-incisor labial tipping, less upper-incisor intrusion and less intrusion of the lower first molar during postsurgical orthodontics. At final follow-up, it also had less vertical intrusion of the lower incisor and first molar.
The findings come from a small retrospective comparison, so they describe an association within this treatment group rather than showing that aligners caused the difference. The authors called the pattern hypothesis-generating and said it should be tested in future powered trials.
How the comparison was made
Researchers compared combined orthodontic-surgical treatment in patients with skeletal Class III malocclusion, a jaw-and-bite alignment problem, who were treated with clear aligners or conventional fixed appliances. The orthodontic treatment was non-extraction, and all 24 patients underwent orthognathic surgery limited to the mandible, or lower jaw. The supplied analysis does not report how many patients were in each appliance group.
To track changes over time, the researchers analyzed lateral cephalometric radiographs, or side-view images used for the study's orthodontic measurements, at three points: before orthodontic treatment (T0), one week before surgery (T1), and at least eight months after surgery (T2). They then compared changes during the presurgical, postsurgical and full treatment intervals.
Statistical tests were performed in SPSS 30, while power calculations were done in G*Power. The report included between-group comparisons and an analysis adjusted for genioplasty. It did not name the specific statistical tests or models in the supplied text.
A split in the pattern of movement
Both groups showed significant skeletal and dentoalveolar changes, meaning changes measured in the jaw, teeth and supporting structures. The reported p-value was below 0.001.
During presurgical decompensation, the stage before surgery when the bite is prepared for the operation, the fixed-appliance group had greater lower-incisor proclination, an outward angling measured using IMPA. The reported p-value was below 0.05. Cohen's d, a statistic used to describe the size of a difference, ranged from -1.13 to 1.27 for the reported comparisons.
During postsurgical orthodontics, the clear-aligner group had less lower-incisor labial tipping, less upper-incisor intrusion and less lower first-molar intrusion. The reported p-value was below 0.05, and the reported d values ranged from -1.03 to 1.1.
At final follow-up, the clear-aligner group had less vertical intrusion of the lower incisor and first molar. This T2-T0 comparison had a reported p-value below 0.05, with d values ranging from 1.11 to 1.17.
After adjustment for genioplasty, clear aligners were associated with superior postsurgical vertical skeletal control, upper-lip retraction and facial convexity. The reported p-value was below 0.05.
A result with a narrow reach
The authors interpreted the pattern as a signal of greater treatment efficiency with clear aligners, alongside less unwanted labial tipping and reduced vertical intrusion. They said fixed appliances showed greater incisor and molar decompensation and recommended future powered trials that test treatment individualization according to biomechanical needs and patient preferences.
The comparison cannot answer whether the appliance itself produced the differences. Because the study was retrospective and treatment was not randomly assigned, factors related to the choice of appliance could be mixed with the measured outcomes. The supplied analysis also does not provide confidence intervals, detailed adjusted estimates or a quantitative treatment-duration result.
The evidence is limited to the reported 24-patient cohort receiving non-extraction orthodontics with mandibular-only surgery. It does not establish superiority for skeletal Class III cases involving extractions, other surgical approaches or nonsurgical treatment. The cephalometric findings also do not establish patient-centered benefit, long-term stability or safety.
The article was published on 21 August 2026 and reports Level of Evidence III. The study received approval from the Ethical Committee of the Affiliated Stomatology Hospital of Guangxi Medical University under approval number 2023030. Huang Xuanping received funding from the National Natural Science Foundation of China, grant 82360187, and Song Shaohua received funding from the Guangxi health appropriate technology development and promotion application project fund, identifier S2021087. The authors declared no conflicts of interest.
Paper data and sources
Original title: A Comparison of Clear Aligners and Fixed Appliances in Orthodontic-Surgical Treatment of Non-Extraction Skeletal Class III Malocclusion.
Authors: Thinzar Zaw, Hsu Yin Min, Yi Wei et al.
Journal/Repository: Aesthetic plastic surgery
Status: Peer-reviewed
First online: 2026-08-21
DOI: 10.1007/s00266-026-06205-3
Original paper · Full text