Samples of bone and teeth from the Middle Paleolithic open-air site of Rozhok I, located on the Gulf of Taganrog, were dated by radiocarbon (14C). We obtained 26 accelerator mass spectrometry (AMS) dates on a large sample of nonhuman bone and teeth recovered by N. D. Praslov during 1961–1962 from 5 of the 6 occupation horizons at Rozhok I. Two rigorous pretreatment methods were applied to the samples: ultra-filtration and XAD resin. The 14C ages from the uppermost two layers (Horizons 1 and 2) are infinite with the exception of one age near the limit of the 14C method. By contrast, the dates from Horizon 3 and the two lowermost layers (Horizons 5 and 6) are all finite ages and some are less than 45,000 BP (uncalibrated). While there is evidence of some post-depositional disturbance, there is no evidence of a stratigraphic reversal of the cultural layers. The simplest explanation for the pattern is that bones and teeth in the lower layers have been contaminated by groundwater containing young carbon. We conclude that Rozhok I probably antedates 50,000 cal BP and is beyond the range of 14C dating.

We investigated age estimation of persons using 45 Japanese human teeth that consisted of mainly the third molar. We measured the radiocarbon content in tooth enamel hydroxyapatite from the crown as well as those in collagen and bioapatite in the root of the same tooth. Age estimations from tooth enamel apatite yielded an absolute age shift of 1.7±1.4 yr from the true age. This value suggests that estimating the age of Japanese people from tooth enamel is as accurate as the previous studies conducted in Europe and the USA. The 14C analysis of roots suggested that bioapatite is formed slightly later than collagen in the same tooth roots. The appropriate formation age ranges suggested by the tooth enamel analysis can be optimized and confirmed by using the additional F14C values of the root samples. We also noticed a characteristic trend of enamel δ13C values in comparison with the formation ages of the crowns of the teeth. The δ13C value tends to increase gradually from –13.0‰ to –11.5‰ from the 1960s to the 1970s, probably being caused by changes in the Japanese diet. This trend may support the selection of proper tooth formation age as supplemental data in addition to 14C content analyses.

This study compared dentinal tubule density and diameter of human primary and permanent teeth at different depths of the coronal dentin. Crowns of eight primary second molars and eight permanent third molars were serially sectioned into three disks of ~0.5 mm thickness (superficial, middle, and deep layers), perpendicular to the long axis. Tubule density and diameter were evaluated in 2,000× and 3,000× magnifications by scanning electron microscopy. Data obtained were subjected to two-way repeated measures ANOVA and Tukey's post hoc test (α = 0.05). Tubule density was greater in primary teeth compared with permanent ones, regardless of depth (primary: 124,329 ± 43,594 mm2; permanent: 45,972 ± 21,098 mm2). In general, the tubule density increased as the dentin depth increased, except to the superficial and middle layers from permanent teeth. Tubule diameter was larger in the dentin layer close to the pulp chamber (superficial: 2.4 ± 0.07 μm; middle: 3.70 ± 0.06 μm; deep: 4.28 ± 0.04 μm). No difference was observed between primary (3.48 ± 0.81 μm) and permanent teeth (3.47 ± 0.73 μm). The tubule diameter increases as the dentin depth increases for primary and permanent teeth; however, the tubule density is higher in primary teeth.