关键词: 锥形束CT, 上颌扩弓矫治, 腭中缝密度比率, 腭中缝成熟程度

Abstract: Objective    To study the variety patterns of the midpalatal suture density ratio in children of different ages（6 to 15 years old）and genders to provide reference for clinical diagnosis and the timing of palatal expansion treatment. Methods    The clinical and imaging data of 164 children aged 6 to 15 years old who visited the West China Hospital of Stomatology from January to December 2023 were collected and analyzed retrospectively. The three-dimensional model of the maxillary complex was reconstructed using Dolphin Imaging software based on cone beam CT data of children. Soft tissue was filtered out to obtain palatal images. ImageJ software was used to measure the grey density of the middle palatal suture and the average grey density of both sides of the palate. The ratio was recorded as the midpalatal suture density ratio，and the differences in the midpalatal suture density ratio in children of different ages and genders were compared. Results    The best regression curve between the midpalatal suture density ratio and age was a fourth power regression curve in male children（R2 = 0.606，P < 0.001），and a fifth power regression curve in female children（R2 = 0.591，P < 0.001）. The change trend of the midpalatal suture density ratio could be divided into flat，declining and rising periods，the corresponding age groups of male children were 6-10 years old，> 10-13，and > 13-15 years old，and the midpalatal suture density ratio was 0.629 ± 0.065，0.510 ± 0.078，and 0.535 ± 0.042. Except for the comparison between the declining and rising periods，the comparisons of midpalatal suture density ratio between each two of other periods showed statistically significant differences（P < 0.05 for all）；the corresponding age groups of female children were 6-9，> 9-12，and > 12-15 years old，and the midpalatal suture density ratio were 0.593 ± 0.062，0.491 ± 0.075，and 0.554 ± 0.061. There were statistical differences in the midpalatal suture density ratio between each two periods（P < 0.05 for all）. Children aged 6-15 were divided into 5 age groups on average. Among them，there were statistically significant differences in the midpalatal suture density ratio in children aged > 7-9，> 9-11，and > 13-15 between different genders（P < 0.05 for all）；there were no statistically significant differences in the midpalatal suture density ratio in children aged 6-7 and > 11-13 between different genders（P > 0.05 for all）. Conclusion    There are differences in the development process of the midpalatal suture in children between different genders. The time point of the change in regression curve between the midpalatal suture density ratio and age in the female is about 1 year earlier than that in the male. Based on the research results and clinical experience，the periods of 7-10 years old in the male and 7-9 years old in the female may be a better opportunity for maxillary expansion，which provides some reference for the formulation of clinical personalized correction plans.

Key words: cone beam CT, maxillary expansion treatment, midpalatal suture density ratio, midpalatal suture maturation