Uchigasaki Ittetsu, Hattori Yoshinori
Division of Aging and Geriatric Dentistry, Department of Oral Rehabilitation Sciences, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan.
BMC Oral Health. 2025 May 28;25(1):816. doi: 10.1186/s12903-025-06191-z.
The forces of the jaw muscles are transmitted to the dentition and the temporomandibular joints (TMJs). Imbalances in the force distribution can lead to occlusal trauma, excessive tooth wear, or TMJ osteoarthritis, making the assessment of bite force (BF) distribution clinically significant. Existing thin-film BF measurement devices capture the magnitudes of a system of BFs distributed at multiple occlusal contacts (OCs), but fail to capture their directional components, limiting their clinical utility. This study aimed to develop a method for representing BF systems as a wrench, a simplified force-couple model, using digital dentistry tools and to evaluate its reliability in terms of interexaminer reproducibility.
A semi-automated system was developed to integrate thin-film BF measurement data with digital models of maxillary and mandibular dental arches. BF systems were represented as wrenches with six parameters: force magnitude, axis location (x, y), axis orientation (frontal, sagittal), and pitch (moment-to-force ratio).Ten young adult participants (5 women, 5 men; mean age: 20.1 ± 2.9 years) were recruited. BF measurements were performed on all participants using the developed system. Two independent examiners manually assigned BFs to the identified OCs separately, and the reliability of these assignments was evaluated based on inter-examiner agreement. Intraclass correlation coefficients (ICCs) for wrench parameters were calculated to assess the consistency of biomechanical outcomes using appropriate statistical tests, with significance set at p < 0.05.
The proposed system allowed substantial automation, and the manual steps were limited to segmenting the interocclusal record model for each mandibular tooth and assigning BFs to the identified OCs. The interexaminer agreement was evaluated for the BFs assigned to the identified OCs, which yielded an 87% match rate. Furthermore, the impact on wrench parameters was assessed using ICCs, which ranged from 0.93 to 0.99, indicating high reliability.
The developed system efficiently integrates BF measurements and three-dimensional OC analysis, providing a practical method for clinical evaluation of the BF systems. In addition, the system provided consistent outcomes in biomechanical analyses across different examiners.
颌骨肌肉的力量传递至牙列和颞下颌关节（TMJ）。力分布不均衡可导致咬合创伤、牙齿过度磨损或TMJ骨关节炎，因此咬合力（BF）分布的评估具有临床意义。现有的薄膜BF测量装置可获取分布于多个咬合接触点（OC）的BF系统的大小，但无法获取其方向分量，限制了它们的临床应用。本研究旨在利用数字牙科工具开发一种将BF系统表示为扳手（一种简化的力-力偶模型）的方法，并从检查者间的可重复性方面评估其可靠性。
开发了一个半自动系统，将薄膜BF测量数据与上颌和下颌牙弓的数字模型整合。BF系统表示为具有六个参数的扳手：力大小、轴位置（x，y）、轴方向（额状面、矢状面）和螺距（力矩与力之比）。招募了10名年轻成年参与者（5名女性，5名男性；平均年龄：20.1±2.9岁）。使用开发的系统对所有参与者进行BF测量。两名独立的检查者分别手动将BF分配给识别出的OC，并根据检查者间的一致性评估这些分配的可靠性。计算扳手参数的组内相关系数（ICC），使用适当的统计检验评估生物力学结果的一致性，显著性设定为p<0.05。
所提出的系统实现了高度自动化，手动步骤仅限于分割每个下颌牙齿的咬合记录模型并将BF分配给识别出的OC。对分配给识别出的OC的BF评估了检查者间的一致性，匹配率为87%。此外，使用ICC评估了对扳手参数的影响，ICC范围为0.93至0.99，表明可靠性高。
开发的系统有效地整合了BF测量和三维OC分析，为BF系统的临床评估提供了一种实用方法。此外，该系统在不同检查者的生物力学分析中提供了一致的结果。
