The periodontal status of removable appliances vs fixed appliances A comparative meta-analysis

Background: Although several researchers have analyzed the dental identity of patients experience with corrective methods using fixed and removable appliances, the consequences stay debatable. This meta-analysis intended to verify whether the periodontal status of removable appliances is similar to that of the conventional fixed appliances. Methods: Relevant literature was retrieved from the database of Cochrane library, PubMed, EMBASE, and CNKI until December 2019, without time or language restrictions. Comparative clinical studies assessing periodontal conditions between removable appliances and fixed appliances were included for analysis. The data was analyzed using the Stata 12.0 software. Results: A total of 13 articles involving 598 subjects were selected for this meta-analysis. We found that the plaque index (PLI) identity of the removable appliances group was significantly lower compared to the fixed appliances group at 3 months (OR = -0.57, 95% CI: -0.98 to -0.16, P = .006) and 6 months (OR = -1.10, 95% CI: -1.60 to -0.61, P = .000). The gingival index (GI) of the removable appliances group was lower at 6 months (OR = -1.14, 95% CI: -1.95 to -0.34, P = .005), but the difference was not statistically significant at 3 months (OR = -0.20, 95% CI: -0.50 to 0.10, P = .185) when compared with that of the fixed appliances group. The sulcus probing depth (SPD) of the removable appliances group was lower compared to the fixed appliances group at 3 months (OR = -0.26, 95% CI: -0.52 to -0.01, P = .047) and 6 months (OR = -0.42, 95% CI: -0.83 to -0.01, P = .045). The shape of the funnel plot was symmetrical, indicating no obvious publication bias in the Begg test (P = .174); the Egger test also indicated no obvious publication bias (P = .1). Conclusion: Our meta-analysis demonstrated that malocclusion patients treated with the removable appliances demonstrated a better periodontal status as compared with those treated with fixed orthodontic appliances. However, the analyses of more numbers of clinical trials are warranted to confirm this conclusion.