Department of Orthodontics, Shenzhen Hospital of Guangzhou University of Chinese Medicine, Shenzhen, China.
Department of Orthodontics, School and Hospital of Stomatology, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangzhou, Guangdong, China.
BMC Oral Health. 2024 Sep 19;24(1):1112. doi: 10.1186/s12903-024-04815-4.
The mandibular retromolar space (RMS) has not been extensively studied in relation to various sagittal skeletal classes and patterns of third-molar eruption. The objective of this study was to test the null hypothesis that there is no difference in the mandibular RMS among normodivergent subjects with different skeletal classes and patterns of mandibular third-molar eruption, using cone-beam computed tomography (CBCT).
A total of 105 normodivergent patients (20-40 years) were included in this study. Participants were categorized into Class I, II and III groups based on ANB and further impacted and erupted groups based on the eruption patterns of the mandibular third molars. Measurements of the mandibular RMS were taken at four planes parallel to the occlusal plane, along the cusp line. Comparative analyses were conducted among the three sagittal groups and between the impacted and erupted groups.
The Class II group exhibited a statistically smaller RMS (P < 0.05). RMS was found to be larger in third-molar erupted group (P < 0.05). The rates of root contact and third-molar impaction was significantly higher in Class II group. (P < 0.05) CONCLUSIONS: The null hypothesis was rejected. Patients with Skeletal Class II tend to have a smaller mandibular RMS and a higher prevalence of root contact and third-molar impaction. The presence of impacted mandibular third molars was correlated with a shorter RMS.
Retrospectively registered.
下颌磨牙后间隙（RMS）与各种矢状骨骼分类和第三磨牙萌出模式的关系尚未得到广泛研究。本研究的目的是使用锥形束计算机断层扫描（CBCT）检验以下无效假设，即不同矢状骨骼分类和下颌第三磨牙萌出模式的正常生长患者的下颌 RMS 之间没有差异。
本研究共纳入 105 名正常生长患者（20-40 岁）。根据 ANB 将参与者分为 I 类、II 类和 III 类，并根据下颌第三磨牙的萌出模式进一步分为未萌出和萌出组。在与咬合平面平行的四个平面上测量下颌 RMS，沿牙尖线进行测量。在三个矢状组之间和萌出组与未萌出组之间进行了比较分析。
II 类组的 RMS 明显较小（P < 0.05）。萌出组的 RMS 较大（P < 0.05）。II 类组的根接触和第三磨牙阻生的发生率明显更高（P < 0.05）。
无效假设被拒绝。骨骼分类为 II 类的患者下颌 RMS 较小，根接触和第三磨牙阻生的发生率较高。下颌第三磨牙阻生与 RMS 较短有关。
回顾性注册。
