Division of Orthodontics, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland.
Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland.
J Morphol. 2024 Aug;285(8):e21755. doi: 10.1002/jmor.21755.
This study aimed to assess the impact of occlusal loading on secondary tooth eruption and to determine the extent to which altering the occlusal loading influences the magnitude of secondary eruption through an experimental rat model. The present sample consisted of 48 male Wistar rats. At the onset of the experiment, 24 rats were 4 weeks old (young rats) and 24 rats were 26 weeks old (adult). Within each age group, the rats were further divided into two equal subgroups (12 rats each), receiving either a soft- or hard-food diet for the 3-month duration of the experiment. The primary outcome was the tooth position changes relative to stable references in the coronal plane by evaluating the distance between the mandibular first molars and the inferior alveolar canal. Microcomputed tomography scans were taken from all rats at three standardized intervals over the 3-month study period. Descriptive statistics were calculated by age and diet over time, and the evolution of the outcomes were plotted by age and diet over time. Longitudinal data analysis via generalized estimating equations was performed to examine the effect of age, diet and time on the primary outcomes. Secondary tooth eruption was observed in all age groups (young and adult) regardless of diet consistency (soft or hard food). In young rats, the secondary eruption was greater in the animals fed a soft diet than those fed a hard diet. In adult rats, minimal difference in secondary tooth eruption were found between different diet consistencies. Occlusal loading influences secondary tooth eruption in teeth with an established occlusal contact. The quantity of eruption in growing rats is higher when occlusal loading is less, providing a certain amount of secondary tooth eruption occurs. This difference, however, is not evident in adult rats, at least during the given 3-month time frame.
本研究旨在评估咬合加载对二次牙萌出的影响，并通过实验性大鼠模型确定改变咬合加载对二次萌出程度的影响。本样本包括 48 只雄性 Wistar 大鼠。在实验开始时，24 只大鼠为 4 周龄（幼鼠），24 只大鼠为 26 周龄（成年鼠）。在每个年龄组内，将大鼠进一步分为两个相等的亚组（每组 12 只），在实验的 3 个月期间分别接受软食或硬食饮食。主要结果是通过评估下颌第一磨牙和下牙槽管之间的距离，相对于冠状面的稳定参考物来评估牙齿位置的变化。在 3 个月的研究期间，对所有大鼠在三个标准化间隔进行微计算机断层扫描。根据年龄和饮食随时间的变化计算描述性统计数据，并根据年龄和饮食随时间的变化绘制结果的演变。通过广义估计方程进行纵向数据分析，以检查年龄、饮食和时间对主要结果的影响。无论饮食一致性（软食或硬食）如何，所有年龄组（幼鼠和成年鼠）均观察到二次牙萌出。在幼鼠中，软食喂养的动物的二次萌出大于硬食喂养的动物。在成年大鼠中，不同饮食一致性之间发现二次牙萌出的差异最小。咬合加载会影响已经建立咬合接触的牙齿的二次牙萌出。当咬合加载较小时，生长中的大鼠的萌出量更高，提供了一定量的二次牙萌出。然而，在成年大鼠中，至少在给定的 3 个月时间范围内，这种差异并不明显。
