Objective:To observe the position of the third molar in the neolithic adults about 6 000 years ago.Methods:On the basis of the maxillary and mandibular specimens preserved in Banpo museum,200 maxillary and mandibular specimens with 383 third molars,187 maxillary and 196 mandibular,were observed for the eruption of the third molar.The teeth in the non-eruption group were further divided into impact group and congenital absent group according to the third molar germ presence testified by X ray.Results:The congenital absent rates of maxillary and mandibular third molar were 26.74% and 17.35%,while the impact rates of maxillary and mandibular third molar were(2.67%) and 14.79% respectively.Conclusion:Both the congenital absent rate and the impact rate of the third molar in neolithic era adults are lower than those in modern,the impact and congenital absence of the third molar are part of degradation of masticatory organ with whole humanity progressing.

Mitochondria play a central role in the regulation of energy metabolism and signal transduction in eukaryotic cells. Although many fluorescent labeling strategies have been developed for mitochondrial studies, the methods that enable labeling efficiency assessment at the single-mitochondrion level are still lacking. By employing the unique advantages of high sensitivity flow cytometry ( HSFCM ) in the sensitive, rapid, and quantitative multiparameter analysis of individual mitochondria, here we examined the performance of several different mitochondrial labeling strategies from the perspectives of brightness, labeling ratio, and stability. Mitochondria isolated from HeLa cells transfected with pAcGFP1-Mito plasmid upon transient or stable transfections, and mitochondria directly labeled with MitoTracker Green or SYTO 62 were analyzed by a laboratory-built three-channel HSFCM. Upon the quantitative measurement of fluorescence brightness, it was found that the fluorescence intensity of green fluorescent protein ( GFP ) in mitochondria isolated from cells with stable transfection was about 17. 7-fold higher than the transient transfection ones, and was approximately two orders of magnitude brighter than mitochondria labeled with MitoTracker Green. On the other hand, the fluorescence signal of SYTO 62 labeling decreased upon washing, indicating its rapid dissociation rate. The strong fluorescence intensity and good labeling stability make stable transfection an efficient method to label mitochondria. The experimental results demonstrates that HSFCM provides a powerful analytical tool to assess the performance of mitochondrial fluorescence labeling via high throughput single mitochondria analysis.

Objective To explore the correlation of caries susceptibility of patients with the immediate tooth polish,application of fluoride,and the patients' oral hygiene habits after interproximal enamel reduction (IER) in clinical practice.Methods The present study retrospectively collected 45 cases of IER (18 males and 27 females) in 196 tooth sites.Each sample was examined clinically and radiologically to obtain the incidence of caries,and the outcome was correlated with amount of IER,tooth polish,application of fluoride,and the brushing method and frequency for statistical analysis.Results The present study showed that there was no statistical significance among the amount of IER,the site of IER,the patients' brushing method,and the gender with the susceptibility of caries.However,there was statistical significance among the application of fluoride,tooth polish and brushing frequency with the susceptibility of caries.Conclusions The current research suggests that it is desirable to polish tooth and apply fluoride for patients with IER in clinical practices.In the meanwhile,the clinician should pay attention to patients' oral hygiene habits,especially brushing frequency,due to the positive correlation between the brushing frequency and incidence of caries.