Association between nonextraction clear aligner therapy and alveolar bone dehiscences and fenestrations in adults with mild-to-moderate crowding

•The aim was to assess alveolar bone defects before and after clear aligner therapy.•Cone-beam computed tomography images were obtained before and after treatment in 29 patients.•Alveolar bone defects were evaluated in buccal and lingual tooth root surfaces.•Alveolar bone dehiscences/fenestrations increased with clear aligner therapy.•Age, pretreatment ANB angle, jaw location, and race were significant predictors.