## 4 Discussion
Although often emphasized inadults, the preservation of periodontal structures is equally crucial in growing patients, making these characteristics highly relevant in this population. These findings suggest that MARPE should be considered preferentially when periodontal stability is a primary treatment objective in growing patients. Nevertheless, a tailored approach that incorporates skeletal maturity assessment, appliance design, and activation protocol remains essential. Heterogeneity (\(I^{2}\)) was noted among the included studies, which could be attributed to variations in appliance design, miniscrew placement, patient age range, and timing of post-expansion assessment. Additionally, differences in activation rates (ranging from 0.4 mm to 0.8 mm per day), retention periods (from 3 to 8 months), and post-expansion evaluation time points likely contributed to the observed heterogeneity. Such procedural inconsistencies highlight the importance of developing consensus guidelines for MARPE protocols to reduce variability and improve comparability across future studies. Despite asymmetry observed in the funnel plot and potential publication bias suggested by [PERSON]'s test, the trim-and-fill analysis indicated that these did not significantly impact the overall effect estimates. The moderate-to-high heterogeneity observed in this study may reflect the clinical variability inherent in MARPE research, where differences in appliance design and activation protocols are commonly present. Differences in radiographic analysis methods and anatomical landmark definitions can contribute to variability in outcomes across studies. In the present meta-analysis, only studies based on CBCT analysis were selected to control for such variables. This approach aimed to enhance the consistency of the results and reduce interpretive discrepancies. Nevertheless, future studies should adopt standardized outcome measures and reporting protocols, such as the CONSORT extension for orthodontic trials, to improve study quality and reproducibility. The current study has several limitations. The number of included trials was limited, with most being single-center studies. Additionally, follow-up durations were often short, and MARPE appliance designs and protocols varied across studies, limiting generalizability. While some studies have shown promising long-term stability for MARPE, most evidence remains confined to short-term outcomes. Future studies should pursue standardized protocols across diverse MARPE designs, with longer follow-up durations, to assess skeletal stability. Subgroup analyses based on age, sex, and skeletal maturity are warranted to refine clinical guidelines and improve patient care. Moreover, comprehensive randomized trials that consider secondary outcomes, such as airway changes, soft tissue adaptation, and miniscrew stability, are necessary to inform broader clinical applications. Finally, the null hypothesis of no significant differences between MARPE and CRPE was partially rejected, as several outcomes demonstrated statistically significant differences favoring MARPE. However, this partial rejection should be interpreted cautiously given the moderate-to-high heterogeneity and the relatively limited number of high-quality randomized trials included.