Department of Orthodontics, School of Dentistry at Matsudo, Nihon University, Chiba, Japan.
Research Institute of Oral Science, School of Dentistry at Matsudo, Nihon University, Chiba, Japan.
J Oral Biosci. 2024 Mar;66(1):20-25. doi: 10.1016/j.job.2024.01.010. Epub 2024 Jan 25.
The current study used a three-dimensional (3D) surface homologous modeling to analyze the structure of maxillary first premolar (P) and second premolar (P) crowns, to identify any morphological differences between them, particularly in their cuspal structures.
The study sample comprised 27 male elementary and junior high school students from Chiba Prefecture, Japan. Plaster casts were collected and the 3D coordinates were used to measure the crown structures. Thereafter, principal component (PC) analysis was carried out using the 3D coordinates of the homologous models, containing 4498 anatomical data points, including 9 landmarks.
The findings indicated that P was significantly larger than P, despite both teeth exhibiting similar intercuspal distances. The homologous model analysis revealed that 61.5 % of the total variance could be explained up to the fourth PC. Overall size and shape in the mesiodistal and buccolingual directions were estimated using PC1 and PC2, respectively. Both components highlighted a shape factor, indicating that the buccal cusp was more well-developed than the lingual cusp in P compared to P.
The variations in the size of the mesial and distal premolar teeth and the relationships between the cusps in the completed tooth crowns can be explained using molecular biology developmental models.
本研究采用三维（3D）表面同型建模分析上颌第一前磨牙（P）和第二前磨牙（P）牙冠的结构，以确定它们之间的形态差异，特别是在牙尖结构方面。
研究样本包括来自日本千叶县的 27 名男性小学生和初中生。收集石膏模型并测量牙冠结构的 3D 坐标。然后，使用包含 9 个标志点的 4498 个解剖学数据点的同源模型的 3D 坐标进行主成分（PC）分析。
尽管 P 和 P 的牙尖间距离相似，但 P 的尺寸明显大于 P。同型模型分析表明，总方差的 61.5%可由第四主成分（PC）解释。PC1 和 PC2 分别用于估计近远中向和颊舌向的整体大小和形状。两个分量均突出了一个形状因子，表明 P 的颊尖比 P 的舌尖发育得更好。
可以使用分子生物学发育模型来解释近远中前磨牙牙齿大小的变化以及完成的牙冠中牙尖之间的关系。
