Oxilia Gregorio, Bortolini Eugenio, Martini Sergio, Papini Andrea, Boggioni Marco, Buti Laura, Figus Carla, Sorrentino Rita, Townsend Grant, Kaidonis John, Fiorenza Luca, Cristiani Emanuela, Kullmer Ottmar, Moggi-Cecchi Jacopo, Benazzi Stefano
Department of Oral and Maxillo Facial Sciences, Sapienza University, Via Caserta 6, Roma 00161, Italy.
Department of Biology, University of Florence, Via del Proconsolo, 12, Firenze 50122, Italy.
Am J Phys Anthropol. 2018 Aug;166(4):941-951. doi: 10.1002/ajpa.23476. Epub 2018 Apr 6.
Exact symmetry and perfect balance between opposite jaw halves, as well as between antagonistic teeth, is not frequently observed in natural masticatory systems. Research results show that asymmetry in our body, skull, and jaws is often related to genetic, epigenetic, environmental and individual ontogenetic factors. Our study aims to provide evidence for a significant link between masticatory asymmetry and occlusal contact between antagonist teeth by testing the hypothesis that tooth inclination is one of the mechanisms driving distribution of wear in masticatory phases in addition to dietary and cultural habits.
The present work investigates the relationship between dental macrowear patterns and tooth inclinations on a sample of complete maxillary and mandibular 3D models of dental arches from 19 young and adult Yuendumu Aboriginal individuals. The analysis was carried out on first molars (M1) from all quadrants. Occlusal Fingerprint Analysis was used for the quantification of macrowear patterns, and 2D cross-sectional geometric analysis was carried out to investigate asymmetry in dental arches.
The asymmetry is highly variable on both arches, and it is associated with differences in the inclination of upper M1 crowns. Each molar has variable inclination (buccal/lingual) which influence tooth to tooth contact, producing greater or lesser variation in wear pattern. Interindividual variability of morphological variation of the occlusal relationship has to be considered in macrowear analysis.
Our results suggest that overall asymmetry in the masticatory apparatus in modern humans affects occlusal contact areas between antagonist teeth influencing macrowear and chewing efficiency during ontogeny.
在自然咀嚼系统中，很少能观察到上下颌两半之间以及拮抗牙之间完全对称和完美平衡的情况。研究结果表明，我们身体、颅骨和颌骨的不对称往往与遗传、表观遗传、环境和个体发育因素有关。我们的研究旨在通过检验以下假设来为咀嚼不对称与拮抗牙之间的咬合接触之间的显著联系提供证据：除饮食和文化习惯外，牙齿倾斜是驱动咀嚼阶段磨损分布的机制之一。
本研究调查了19名年轻和成年云杜姆原住民个体完整的上颌和下颌牙弓三维模型样本中牙齿宏观磨损模式与牙齿倾斜之间的关系。分析针对所有象限的第一磨牙（M1）进行。使用咬合指纹分析对宏观磨损模式进行量化，并进行二维横截面几何分析以研究牙弓的不对称性。
两个牙弓上的不对称性变化很大，并且与上颌M1牙冠倾斜度的差异有关。每颗磨牙都有可变的倾斜度（颊侧/舌侧），这会影响牙齿之间的接触，从而在磨损模式上产生或多或少的变化。在宏观磨损分析中必须考虑个体间咬合关系形态变化的变异性。
我们的结果表明，现代人类咀嚼器官的整体不对称会影响拮抗牙之间的咬合接触区域，从而影响个体发育过程中的宏观磨损和咀嚼效率。
