External apical root resorption induced by orthodontic treatment is a known complication of orthodontic tooth movement. A systematic review and meta-analysis published in 2025 compared root resorption in patients treated with clear aligners and those treated with fixed orthodontic appliances.
Study findings
The analysis included 10 studies, consisting of one randomized controlled trial, two prospective studies and seven retrospective studies.
In total, 286 patients (1476 incisors) treated with aligners and 289 patients (1487 incisors) treated with fixed appliances were evaluated.
The meta-analysis showed that clear aligners produced significantly less external apical root resorption than fixed appliances, except in mandibular lateral incisors.
The mean difference in favor of aligners was:
- −0.64 mm in maxillary central incisors
- −0.26 mm in mandibular central incisors
Clinical implications
The authors concluded that external apical root resorption in incisors is generally lower in patients treated with clear aligners than in those treated with fixed orthodontic appliances.
However, they emphasized that additional studies are needed to confirm these findings and to better determine their clinical relevance.