Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
PLoS One. 2013 Apr 24;8(4):e62263. doi: 10.1371/journal.pone.0062263. Print 2013.
Over the last century, humans from industrialized societies have witnessed a radical increase in some dental diseases. A severe problem concerns the loss of dental materials (enamel and dentine) at the buccal cervical region of the tooth. This "modern-day" pathology, called non-carious cervical lesions (NCCLs), is ubiquitous and worldwide spread, but is very sporadic in modern humans from pre-industrialized societies. Scholars believe that several factors are involved, but the real dynamics behind this pathology are far from being understood. Here we use an engineering approach, finite element analysis (FEA), to suggest that the lack of dental wear, characteristic of industrialized societies, might be a major factor leading to NCCLs. Occlusal loads were applied to high resolution finite element models of lower second premolars (P2) to demonstrate that slightly worn P2s envisage high tensile stresses in the buccal cervical region, but when worn down artificially in the laboratory the pattern of stress distribution changes and the tensile stresses decrease, matching the results obtained in naturally worn P2s. In the modern industrialized world, individuals at advanced ages show very moderate dental wear when compared to past societies, and teeth are exposed to high tensile stresses at the buccal cervical region for decades longer. This is the most likely mechanism explaining enamel loss in the cervical region, and may favor the activity of other disruptive processes such as biocorrosion. Because of the lack of dental abrasion, our masticatory apparatus faces new challenges that can only be understood in an evolutionary perspective.
在上个世纪，工业化社会的人类见证了一些口腔疾病的急剧增加。一个严重的问题涉及到牙齿颊颈区域的牙体硬组织（牙釉质和牙本质）的丧失。这种“现代”病理学，称为非龋性颈病变（NCCLs），是普遍存在且全球性分布的，但在工业化前社会的现代人中非常罕见。学者们认为有几个因素与此相关，但这种病理学背后的真正动态还远未被理解。在这里，我们使用工程方法，有限元分析（FEA），来表明工业化社会中缺乏牙齿磨损可能是导致 NCCLs 的一个主要因素。我们将咬合负荷施加到下颌第二前磨牙（P2）的高分辨率有限元模型上，以证明稍微磨损的 P2 会在颊颈区域产生高拉伸应力，但当在实验室中人为地磨损时，应力分布的模式会发生变化，拉伸应力会降低，与在自然磨损的 P2 中获得的结果相匹配。在现代工业化世界中，与过去的社会相比，高龄个体的牙齿磨损程度非常适中，而牙齿在颊颈区域要承受数十年的高强度拉伸应力。这是解释牙颈部釉质丧失的最可能机制，并且可能有利于其他破坏性过程（如生物腐蚀）的活动。由于缺乏牙齿磨损，我们的咀嚼器官面临着新的挑战，只有从进化的角度才能理解这些挑战。
