Effects of bone-anchored maxillary protraction in cleft lip and palate - a single-arm prospective observational study

Abstract

To describe changes in maxillofacial morphology observed during bone-anchored maxillary protraction (BAMP) treatment in children with cleft lip and palate (CLP). This prospective, single-arm observational study included 20 consecutively treated patients with CLP (60% male; mean age at baseline (T1), 11.7 ± 1.0 years) who underwent BAMP therapy as part of a treatment protocol. Lateral cephalograms were obtained at baseline (T1) and at the end of maxillary protraction (T2; mean age, 15.3 ± 1.6 years). Protraction was considered complete when a positive overjet with adequate incisor overlap had been achieved and judged stable by the treating orthodontist, or when no further sagittal improvement was observed over two consecutive annual reviews, after which the miniplates were removed. Skeletal and dental changes were assessed using cephalometric measurements. Method error was evaluated using intraclass correlation coefficients. Statistical analyses included paired comparisons and exploratory univariable regression analyses. Significant increases were observed in the SNPg angle, midfacial length, mandibular length, and maxillomandibular difference, accompanied by a significant reduction in the SN/GoMe angle. The SNA angle increased by 1.3° from T1 to T2; however, this change did not reach statistical significance (95% CI: -0.17 to 2.66). Exploratory univariable analyses suggested that baseline age and observation time were associated with selected skeletal changes; these analyses were hypothesis-generating only. BAMP therapy was not associated with a statistically significant change in maxillary sagittal position (SNA), and overall skeletal changes were modest; clinicians should therefore maintain realistic expectations regarding the extent of skeletal correction achievable. Because the primary outcome (SNA) was not statistically significant, these findings are hypothesis-generating; whether BAMP can stabilise maxillary position during growth in milder discrepancies, and thereby reduce the likelihood of later orthognathic surgery, requires confirmation in controlled studies. Because the study had no control group, the observed T1-T2 changes cannot be separated from normal growth, and no causal effect of BAMP can be inferred.