Mahoney Patrick, McFarlane Gina, Pitfield Rosie, O'Hara Mackie C, Miszkiewicz Justyna J, Deter Chris, Seal Hannah, Guatelli-Steinberg Debbie
School of Anthropology and Conservation, University of Kent, Canterbury CT2 7N, UK.
School of Anthropology and Conservation, University of Kent, Canterbury CT2 7N, UK.
J Struct Biol. 2020 Aug 1;211(2):107550. doi: 10.1016/j.jsb.2020.107550. Epub 2020 Jun 15.
Life on earth is regulated by biological rhythms, some of which oscillate with a circadian, monthly or lunar cycle. Recent research suggests that there is a near weekly biorhythm that may exert an influence on human skeletal growth. Evidence for the timing of this biorhythm is retained in tooth enamel as the periodicity of Retzius lines. Studies report that Retzius periodicity (RP) relates to adult human stature and enamel thickness. Adult human stature is sexually dimorphic, and so is enamel thickness of maxillary third molars (M3) but not mandibular M3. Yet, previous studies report sex differences in RP are apparent in some populations but not others, and it is unknown if dimorphism in enamel thickness relates to RP. To further our understanding of this biorhythm we analysed sex-related variation in RP and its relationship with enamel thickness in a sample of M3's (n = 94) from adults in Northern Britain. Results reveal RP was significantly higher in our sample of female molars compared to those of males, which is consistent with the previously reported correlation between the biorhythm and adult stature. The RP of maxillary M3 related to sex differences in enamel thickness, but this relationship was not present in mandibular M3. Our results support previous findings suggesting that this biorhythm is sexually dimorphic and provide the first evidence that RP may be one factor influencing sex differences in enamel thickness. Our study also shows that correlations between RP and enamel thickness appear to be most readily detected for tooth types with sufficiently wide ranges of enamel thickness variation, as is the case for maxillary but not mandibular M3. Achieving a sufficient sample size was critical for detecting a sex difference in periodicity.
地球上的生命受生物节律调节，其中一些节律以昼夜、每月或月球周期振荡。最近的研究表明，存在一种近乎每周一次的生物节律，可能会对人类骨骼生长产生影响。这种生物节律的时间证据保留在牙釉质中，表现为芮氏线的周期性。研究报告称，芮氏周期性（RP）与成年人身高和牙釉质厚度有关。成年人身高存在性别差异，上颌第三磨牙（M3）的牙釉质厚度也存在性别差异，但下颌M3不存在。然而，先前的研究报告称，RP的性别差异在一些人群中明显，而在另一些人群中则不明显，牙釉质厚度的二态性是否与RP相关尚不清楚。为了进一步了解这种生物节律，我们分析了来自英国北部成年人的M3样本（n = 94）中RP的性别相关变异及其与牙釉质厚度的关系。结果显示，与男性磨牙样本相比，我们的女性磨牙样本中的RP显著更高，这与先前报道的生物节律与成年身高之间的相关性一致。上颌M3的RP与牙釉质厚度的性别差异有关，但下颌M3不存在这种关系。我们的结果支持了先前的研究结果，表明这种生物节律具有性别二态性，并提供了第一个证据，即RP可能是影响牙釉质厚度性别差异的一个因素。我们的研究还表明，对于牙釉质厚度变化范围足够宽的牙齿类型，如上颌但不是下颌M3，RP与牙釉质厚度之间的相关性似乎最容易检测到。获得足够的样本量对于检测周期性的性别差异至关重要。
