Aligners Released No More BPA Into Saliva Than Fixed Appliances in Randomized Trial

Edited by Orthotown staff

Salivary bisphenol A levels did not differ between patients treated with three types of clear aligners and patients treated with fixed appliances, according to a randomized trial published Sept. 24 in the Journal of Orofacial Orthopedics.

Researchers randomly allocated 52 patients to four groups: directly 3D-printed aligners, Invisalign aligners, ClearCorrect aligners, and fixed orthodontic appliances. Saliva samples were collected at baseline and at several points during the first and final weeks of treatment and analyzed by high-performance liquid chromatography. Treatment effectiveness was scored with the Peer Assessment Rating index from intraoral scans taken at the start and end of treatment.

BPA levels showed no statistically significant differences among the four groups at any time point. The percentage reduction in PAR scores also did not differ significantly between groups.

Treatment time did differ. Mean duration was 6.59 months with directly printed aligners, 5.36 months with Invisalign, 5.72 months with ClearCorrect, and 10.16 months with fixed appliances. The fixed-appliance group took significantly longer than the aligner groups (P < .001).

The authors concluded that BPA release did not differ among the treatment modalities, and that direct and indirect aligner techniques were as effective as fixed treatment. They wrote that longer-term studies are needed to clarify the biological relevance of the BPA findings.

Nizami Hashimli, Ahmet Yagci, and Mehmet Cadir conducted the study, with the Department of Orthodontics at Erciyes University’s Faculty of Dentistry in Kayseri, Türkiye. It was funded by the Scientific and Technological Research Council of Türkiye.

With 52 patients split across four groups, each arm was small. BPA was measured in saliva only during the first and final weeks of treatment, so the trial does not address cumulative exposure over the full course of care.

Sources:
Journal of Orofacial Orthopedics, “Comparison of different clear aligner systems with fixed orthodontic treatment in terms of endocrine-disrupting monomer release, treatment effectiveness, and efficiency,” published online Sept. 24, 2026: link.springer.com/10.1007/s00056-026-00690-6