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Evaluation of Palatal Bone Thickness for Insertion of Orthodontic Mini-Implants in Adults and Adolescents

Objective: The aim of this study was to measure palatal bone thickness and select relatively safe regions for mini-implant insertion, and to determine the effect of age and sex on palatal bone thickness and whether there is any difference between right and left sides. Materials and Methods: Cone beam computed tomographic (CBCT) evaluation was used on 107 healthy orthodontic patients, including 51 adolescents (12.90 ± 1.71 years) and 56 adults (26.09 ± 4.35 years), who were selected from the Zhongshan Hospital, Fudan University (Shanghai, China). Seventy-two sites of bone thickness were measured in the palate. Intragroup, intergroup, and sex differences were analyzed by repeated measures analysis of variance. Results: Palatal bone thickness exhibited significant differences in 3 anteroposterior areas of the 2 groups. From anterior to posterior region, palatal bone thickness gradually decreased. Meanwhile, on the sagittal plane, palatal bone thickness decreased gradually from reference line 0 to 9 mm among adults, and from reference line 0 to 12 mm among adolescents posterior to the level of the posterior rim of the incisive foramen. However, on the coronal plane, no significant differences were found in the palatal bone thickness among reference lines 2, 4, 6, and 8 mm lateral to the midpalatal suture. Nor were there differences between right and left sides, between adults and adolescents or between males and females. Conclusions: In terms of bone thickness, the anterior region is relatively safe for orthodontic mini-implant insertion. However, since subjects vary greatly, CBCT scans are needed before undertaking mini-implant insertion.