Abstract
Transverse maxillary deficiency, a common skeletal discrepancy among children and adolescents globally, can be treated using either bone-anchored (BA) and tooth-borne (TB) maxillary expanders. This systematic review and meta-analysis evaluated the three-dimensional (3D) difference in the skeletal and dentoalveolar effects of both expander types in growing patients. A systematic literature search was performed across four electronic databases to identify randomised clinical trials that evaluated the skeletal and dentoalveolar effects of BA and TB maxillary expanders using 3D radiographic images with comparisons made immediately after expansion, within 6 months, and beyond 6 months. Following risk of bias assessment, dimensional changes in sutural expansion (SE), nasal width (NW), maxillary width (MW), as well as tooth inclination (TI) and buccal bone thickness (BBT) of posterior tooth regions were extracted and pooled for further meta-analyses. The analyses were performed based on evaluation periods to determine immediate, short-term, and long-term effects. Among 1432 records that have been retrieved, ten studies followed our predetermined eligibility criteria, thus included in this systematic review for qualitative synthesis. Nine of them were able to undergo quantitative synthesis. Regarding the immediate effect, BA expanders presented significantly higher SE, NW, and MW changes than TB expanders, while showing no significant difference in TI and BBT at the molar region. During the first 6 months after expansion (short-term), evidence has shown that the skeletal and dentoalveolar effects were more favourable to BA expanders in terms of greater nasal width changes and less TI for premolars and molars. However, there were particularly insufficient studies that investigated the long-term skeletal and dentoalveolar effect differences, though there might be greater nasal width changes after 6 months. Current evidence suggests that hybrid/BA expanders produce significantly greater skeletal effect than tooth-borne expanders in the immediate and short term. These effects include increased sutural opening and nasal width, alongside less premolar buccal tipping and greater buccal bone thickness at the premolar and molar region less than 6 months after expansion. Over time, the differences between groups appear to diminish time, indicating potential instability in the long-term outcomes. Due to the high heterogeneity among studies and low quality of evidence reported, these findings should be interpreted with caution. Further studies with more standardised ways would be needed, particularly for long-term changes. REGISTRATION: PROSPERO (CRD42023399235).