Evaluation of palatal bone thickness and palatal depth angle for optimal mini-implant placement in MARPE: A CBCT study

Abstract

CONTEXT: Mini-implant-assisted rapid palatal expansion (MARPE) has become an effective nonsurgical method for maxillary expansion in adults. The success of this method depends on the proper placement of mini-implants. AIMS: This study aimed to assess the thickness of the palatal bone (TPB), palatal bone density (PBD), and thickness of the palatal soft tissue (TPS) using cone-beam computed tomography (CBCT) and to explore their relationships with the palatal depth angle (PDA). SETTINGS AND DESIGN: A retrospective cross-sectional study analyzed CBCT scans of 61 adults (31 males, 30 females; average age: 23.9 ± 7 years) conducted at the Faculty of Dentistry, Sana’a University. METHODS AND MATERIALS: Measurements of TPB, PBD, and TPS were obtained at 14 sagittal levels starting 3 mm posterior to the incisive foramen and continuing at 2-mm intervals and bilaterally at 3 and 6 mm from the midpalatal suture, resulting in 56 measurement points per scan. PDA was measured as the angle formed by the anterior alveolar crest, the deepest palatal point, and the posterior nasal spine. STATISTICAL ANALYSIS USED: Intra-examiner reliability was evaluated using the intraclass correlation coefficient. Data analysis was performed using the Statistical Package for the Social Sciences version 25.0 (IBM, Armonk, USA). A P-value <0.05 was considered statistically significant. RESULTS: TPB and PBD were the greatest in the anterior region and gradually decreased toward the posterior palate (P < 0.001). Males showed significantly higher TPB values (P < 0.01), and PBD differences between genders were minimal. TPS was generally higher at lateral points (P < 0.05). A significant positive correlation was observed between PDA and TPB, especially in the anterior (r = 0.324, P < 0.001) and middle regions (r = 0.476, P < 0.001). CONCLUSION: Variations in TPB and PBD help identify the most favorable regions for mini-implant placement. The anterior and middle regions are suitable for implant placement and offering bicortical anchorage when TPB is inadequate in the middle. A higher PDA (indicating a flatter palate) correlated with greater TPB in these areas—and vice versa.