Department of Orthodontics, Bauru Dental School, and Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, São Paulo, Brazil.
Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2021 Feb;159(2):184-192. doi: 10.1016/j.ajodo.2019.12.021. Epub 2020 Dec 31.
This study aimed to evaluate the 3-dimensional (3D) mandibular dental changes over 42 years using the registration of digital models.
The sample comprised digital dental models of 8 untreated subjects (4 males and 4 females) with normal occlusion measured longitudinally at ages 17 years (T1) and 60 years (T2). Using 13 landmarks placed on the mucogingival junction, we registered the T2 model on the T1 model. Three-dimensional changes in the position of the landmarks on the buccal cusp tip of the posterior teeth and incisal edge of the central incisors were measured by 2 examiners. Registration and measurements were performed using SlicerCMF (version 3.1; http://www.slicer.org) software. Intra- and interrater agreements were evaluated using intraclass correlation coefficients and the Bland-Altman method. One-sample t tests were used for evaluating interphase 3D dental changes (P <0.05).
Adequate intra- and interrater reproducibility was found. From T1 to T2, the mandibular teeth showed significant 3D positional changes. A significant dental eruption relative to the mucogingival junction was observed for the anterior and posterior teeth. Anteroposterior movements of mandibular teeth were not significant except for the right molar that drifted mesially. Transverse movements included slight lingual tipping at canines and premolars regions.
Dental changes in untreated normal occlusion were very slight from early to mature adulthood. The eruption of the mandibular teeth was the most consistent finding. A tendency for mesial movement of molars and lingual movement of first premolars and canines was observed in the mandible during the aging process.
本研究旨在通过数字化模型的配准来评估下颌牙 42 年来的三维（3D）变化。
该样本包括 8 名未经治疗的受试者（4 名男性和 4 名女性）的数字牙模型，这些受试者具有正常的咬合关系，分别在 17 岁（T1）和 60 岁（T2）时进行纵向测量。我们使用放置在龈粘膜交界处的 13 个标志点，将 T2 模型配准到 T1 模型上。由 2 名检查者测量后牙颊尖和中切牙切缘标志点在三维位置上的变化。使用 SlicerCMF（版本 3.1；http://www.slicer.org）软件进行注册和测量。使用组内相关系数和 Bland-Altman 方法评估了内和间的一致性。使用单样本 t 检验评估了相间的 3D 牙齿变化（P<0.05）。
发现内和间的评估具有足够的重现性。从 T1 到 T2，下颌牙齿出现了明显的三维位置变化。前牙和后牙相对于龈粘膜交界处有明显的牙齿萌出。下颌牙齿的前后向运动不明显，但右侧磨牙向近中漂移。横向运动包括尖牙和前磨牙区的轻微舌倾。
在正常咬合的未治疗者中，从早期到成熟成人期，牙齿变化非常轻微。下颌牙齿的萌出是最一致的发现。在衰老过程中，观察到磨牙向近中移动和第一前磨牙和尖牙向舌侧移动的趋势。
