Evaluation of optical density of the midpalatal suture 3 months after surgically assisted rapid maxillary expansion

Objectives: This study evaluated new bone formation at the midpalatal suture after surgically assisted rapid maxillary expansion (SARME) by optical density analysis. Methods: The study population consisted of 18 patients, 10 males and 8 females. All patients presented maxillary atresia with posterior crossbite and were submitted to SARME. Maxillary occlusal radiographs were taken at three stages (before SARME, immediately after SARME and after 3 months). Three patients did not attend the session at the 3-month period for achievement of the occlusal radiography and thus were excluded, leading to a final sample of 15 patients. Two regions were selected and analysed at each stage. Region A measured 8 X 1 mm(2) and was located 1.2 cm from the tangent to the maxillary central incisors at the region of the midpalatal suture. Region B measured 5 X 9 mm(2) and was located 4.3 cm from the tangent to the maxillary central incisors at the region of the midpalatal suture. An aluminium scale (step wedge) with eight steps varying from 1 mm to 8 mm was adapted at the end of the films. Radiographs were taken on a Spectro 70X machine (Dabi Atlante, Ribeirdo Preto, Brazil) set at 70 kVp and 10 mA with an exposure time of 1.0 s. Radiographs were scanned using a Power Look 1000 scanner (Umax, Taiwan, China) and a computer Dimension E510 (Dell Computer, Taiwan, China). Optical density analysis was performed after digitization of radiographs using the software Image Tool (UTHSCSA, San Antonio, TX). Results: Statistical analysis of region A revealed statistically significant differences between Stages I and II (P = 0.0001), Stages II and III (P = 0.0001) and Stages I and III (P = 0.0003). In region B, statistically significant differences were observed between Stages I and II, I and III and II and III (P = 0.0018, P = 0.0003 and P = 0.0003, respectively). Conclusions: Optical density analysis improves post-treatment control of SARME procedures by surgeons and orthodontists. After 3 months, new bone formation at the midpalatal suture is not complete.