Temporomandibular joint changes after orthodontic treatment with clear aligners: A scoping review

To review the available evidence on temporomandibular joint morphological changes after orthodontic treatment with clear aligners, as assessed using CBCT scans.

This review sought randomized clinical trials, controlled or comparative clinical trials, and retrospective cohort studies. The primary outcomes were condylar position and joint spaces, and the secondary outcomes were condylar dimensions and inclination, and mandibular fossa dimensions. MEDLINE (via PubMed), Scopus, Web of Science, ProQuest, and the Clinical Trials Registration and the WHO International Clinical Trials Registry Platforms were searched. The risk of bias was assessed using the ROBINS-I tool.

The review included four retrospective studies with high heterogeneity and risk of bias. Each study addressed a different type of malocclusions; Class I, Class II (unspecified division), Class II division 1, and Class II division 2. After clear aligner treatment in adults, no significant changes were observed in condylar position or joint spaces in Class I non-extraction and extraction cases, as well as in Class II non-extraction cases while, Class II division 2 non-extraction cases demonstrated improvement in initially posteriorly positioned condyles. A similar change was reported in skeletal Class II division 1 adolescents treated with functional clear aligners. Results suggest that growth plays a significant role in influencing condylar position and mandibular fossa dimensions.

The evidence is derived from four studies with a serious risk of bias, therefore should be interpreted as exploratory rather than confirmatory. This review highlights a research gap that warrants further investigation through high-quality studies followed by systematic reviews.