Root resorption caused by aligners, self-ligating appliances, and conventional fixed appliances: a CBCT-based meta-analysis

Abstract Background Orthodontically induced inflammatory root resorption (OIIRR) is a common adverse effect of orthodontic treatments. Radiographs are routinely used to diagnose OIIRR; however, 3-dimensional cone beam computed tomography (CBCT) studies have recently been conducted to assess hard tissue loss more accurately. There is controversial evidence of differences between aligners and fixed appliances in terms of OIIRR. This meta-analysis aims to investigate the differences in OIIRR between fixed appliances and aligners based on recent CBCT-based studies. Methods A systematic review and meta-analysis was conducted after PROSPERO registration. Four databases (MEDLINE, Embase, CENTRAL, Scopus) were systematically screened to identify studies reporting on (P) patients with full permanent dentition treated with (I) aligners or (C) fixed orthodontic appliances that reported on (O) root resorption detected by CBCT, without any date or language restrictions. Exclusion criteria included incomplete dentition, root canal treatment, dental trauma, previous root resorption, and developmental abnormalities. Means and mean differences were used as effect size measures, Chi-squared tests for subgroup differences, and I 2 values for heterogeneity were calculated. Risk of bias was evaluated using ROBINS-I and RoB2 tools. Results The meta-analysis included five studies with 334 participants. Data on upper incisors were sufficient for analysis. Differences in OIIRR between aligners and fixed appliances did not reach statistical significance ( p > 0.05), and neither group presented clinically relevant OIIRR (< 1 mm). A moderate to high risk of bias was present. Discussion All treatment modalities caused similar, clinically irrelevant levels of OIIRR in the investigated population. The treatment modality should be selected based on biomechanics, expected outcomes, and individual preferences. Clinicians should not prioritize aligners over fixed appliances in the non-risk population in fear of OIIRR. The results should be interpreted cautiously due to the risk of bias and heterogeneity. Registration PROSPERO: CRD42023481411.