Cementum is a mineralized dental tissue common to mammals that grows throughout life, following a seasonally appositional rhythm. Each year, one thick translucent increment and one thin opaque increment is deposited, offering a near-complete record of an animal's life history. Male and female mammals exhibit significant differences in oral health, due to the contrasting effects of female versus male sex hormones. Oestrogen and progesterone have a range of negative effects on oral health that extends to the periodontium and cementum growth interface. Here, we use synchrotron radiation-based X-ray tomography to image the cementum of a sample of rhesus macaque (Macaca mulatta) teeth from individuals of known life history. We found that increased breeding history in females corresponds with increased increment tortuosity and less organized cementum structure, when compared to male and juvenile cementum. We quantified structural differences by measuring the greyscale ‘texture’ of cementum and comparing results using principal components analysis. Adult females and males occupy discrete regions of texture space with no overlap. Females with known pregnancy records also have significantly different cementum when compared with non-breeding and juvenile females. We conclude that several aspects of cementum structure and texture may reflect differences in sexual life history in primates.

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基于同步辐射的 X 射线断层扫描揭示灵长类牙骨质增生的生活史

牙骨质是哺乳动物常见的矿化牙齿组织，它在一生中都会按照季节性同位节奏生长。每年，都会沉积一个厚厚的半透明增量和一个薄的不透明增量，提供动物生活史的近乎完整的记录。由于雌性与雄性性激素的对比作用，雄性和雌性哺乳动物在口腔健康方面表现出显着差异。雌激素和孕激素对口腔健康有一系列负面影响，这些影响延伸到牙周和牙骨质生长界面。在这里，我们使用基于同步辐射的 X 射线断层扫描对来自已知生活史的恒河猴 (Macaca mulatta) 牙齿样本的牙骨质进行成像。我们发现，与雄性和幼年牙骨质相比，雌性增加的繁殖历史与增加的弯曲度增加和组织较少的牙骨质结构相对应。我们通过测量牙骨质的灰度“质地”并使用主成分分析比较结果来量化结构差异。成年女性和男性占据纹理空间的离散区域，没有重叠。与非繁殖和幼年雌性相比，具有已知怀孕记录的雌性也具有显着不同的牙骨质。我们得出结论，牙骨质结构和质地的几个方面可能反映了灵长类动物性生活史的差异。我们通过测量牙骨质的灰度“质地”并使用主成分分析比较结果来量化结构差异。成年女性和男性占据纹理空间的离散区域，没有重叠。与非繁殖和幼年雌性相比，具有已知怀孕记录的雌性也具有显着不同的牙骨质。我们得出结论，牙骨质结构和质地的几个方面可能反映了灵长类动物性生活史的差异。我们通过测量牙骨质的灰度“质地”并使用主成分分析比较结果来量化结构差异。成年女性和男性占据纹理空间的离散区域，没有重叠。与非繁殖和幼年雌性相比，具有已知怀孕记录的雌性也具有显着不同的牙骨质。我们得出结论，牙骨质结构和质地的几个方面可能反映了灵长类动物性生活史的差异。