Renz H, Radlanski R J
Charité--Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Zahn-, Mund- und Kieferheilkunde, Abteilung Experimentelle ZMK, 14197 Berlin, Germany.
Homo. 2006;57(1):29-50. doi: 10.1016/j.jchb.2005.09.002. Epub 2005 Oct 28.
In root cementum of teeth, alternating dark and light lines become visible in cross-sections under the light microscope. These lines bear an apparent resemblance to the annual rings of trees. Numerous studies have been done to correlate the number of cementum lines with the dental age by examining a great number of teeth of known age. Our study used a different approach. If lines in root cementum develop in an annual rhythm and are thus comparable to annual rings of trees, the same or at least a very similar number of these structures should be found in all areas of the root cementum of the same tooth. We counted cementum lines in the buccal, lingual, distal and mesial region of different sections, all from the middle third of the same root. This was repeated in eight teeth. To our surprise, we had immense difficulty in counting reproducible line numbers in the same cementum area at repeated counts. Nevertheless, the same tooth was found to differ markedly in the number of lines in different sections as well as in different regions of the same sections. These differences cannot be ascribed to variations caused by difficulties with reproducible line counting. Therefore, we are more than skeptical about the reliability of counting lines in root cementum as a method for determining the age of human teeth.
在牙齿的牙根牙骨质中，在光学显微镜下观察其横断面时，明暗交替的线条清晰可见。这些线条与树木的年轮明显相似。通过检查大量已知年龄的牙齿，已经进行了许多研究来关联牙骨质线条的数量与牙龄。我们的研究采用了不同的方法。如果牙根牙骨质中的线条以年度节律形成，因此与树木的年轮具有可比性，那么在同一颗牙齿的牙根牙骨质的所有区域中应该发现相同或至少非常相似数量的这些结构。我们对来自同一牙根中间三分之一处的不同切片的颊侧、舌侧、远中侧和近中侧区域的牙骨质线条进行了计数。在八颗牙齿上重复了这一操作。令我们惊讶的是，在重复计数时，我们在同一牙骨质区域中难以重复地数出线的数量。然而，同一颗牙齿在不同切片以及同一切片的不同区域中的线条数量也存在显著差异。这些差异不能归因于因难以重复计数线条而导致的变化。因此，我们对将牙根牙骨质中的线条计数作为确定人类牙齿年龄的方法的可靠性深表怀疑。
