Investigation of the effects of tooth-borne and bone-borne rapid maxillary expansion on alveolar bone quantity and periodontal soft tissues

Objective: The aim of this study is to comparatively examine the effects on alveolar bone tissue and periodontal soft tissues in tooth-borne and bone-borne rapid maxillary expansion treatment. Methods: Our study included 24 patients (11 males, 13 females), aged 11–16, who received a rapid maxillary expansion appliance with a tooth-borne design on one side and a bone-borne design on the other. For each patient, plaque index, gingival index, bleeding on probing, probing depth, keratinized gingiva width, and gingival biotype as well as buccal alveolar bone thickness and height in the posterior region obtained from CBCT images were evaluated before treatment (T0) and three months after expansion (T1). For intragroup and intergroup comparisons, the paired samples t-test was used for continuous variables, the McNemar test for categorical variables, and the Wilcoxon signed-rank test for ordinal variables. Results: A significant increase in gingival index and bleeding on probing was observed on the tooth-borne side, while probing depth showed significant increases in both groups, being more pronounced in the tooth-borne group. The width of keratinized gingiva decreased significantly only at the first molar in the bone-borne group, with no intergroup differences. Gingival biotype exhibited a significant shift from thin to medium in the first premolar and first molar regions on the tooth-borne side. Buccal alveolar bone thickness decreased most prominently at the coronal level in both groups, with apical levels showing no significant change. No intergroup differences were detected for bone thickness. Buccal alveolar bone height decreased significantly in both groups. Conclusion: Significant resorption was observed in the alveolar bone tissue in both treatment methods. When evaluated in terms of periodontal soft tissues, the effects observed in the tooth-borne group were found to be more pronounced. Keywords: bone-borne, CBCT, periodontal soft tissue, rapid maxillary expansion, tooth-borne