Cementogenesis starts with the differentiation of dental follicular cells into cementoblasts. In this process, the invasion of dental follicular cells into the chinks of the ruptured Hertwig’s Epithelial Root Sheath (HERS) is considered to be a key factor. However, little is known about the mechanisms involved in degradation of the basement membrane surrounding HERS. Perlecan is one of the main basement membrane heparan sulfate (HS) proteoglycans. When root formation progresses, perlecan becomes scarce on the basement membrane of HERS. In contrast, HERS cells show intense labeling for heparanase that cleaves HS chains in perlecan. These results indicate that heparanase secreted by the cells of HERS may contribute to root and periodontal tissue formation by degrading perlecan in the basement membrane of HERS.

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Skeletal remains excavated from the Nukdo archeological site (2100-2000yrs B. P.) are the most ancient of the sizable number found in Korea to date. In the present study, we focused on the caries rates, carious sites, degree of dental attrition, and ritual tooth ablation in skeletal remains excavated from the Nukdo site. The caries rate was 6.4%. This rate was lower than the Yayoi people in Japan as well as the Jomon people, who were hunters and gatherers. An interest for future studies is the type of diet of these Nukdo individuals. For carious sites, half of the caries were seen on the root surfaces even in individuals who were relatively young. As we have emphasized previously, this can be explained by the rapid advancement of physiological age in ancient people. Thus, root caries seen in the present elderly were found in young individuals in the past. The degree of dental attrition was higher in males than females in all age groups. The mandibular teeth had more attrition than the maxillary teeth except in one male in the late middle-age or older group. An investigation of such attrition is valuable when examining the diet and livelihood of people of that time. For ritual tooth ablation, the form of extraction in the Nukdo people appears different from that in the Jomon people in Japan or prehistoric people in China. The origin of this type of ablation is a topic of future studies.

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Relaxin, a member of the insulin/relaxin family of structurally related hormones, binds to receptors that are part of the leucine-rich repeat G-protein receptor family (LGR7 and LGR8). Furthermore, it influences many other physiologic processes, such as collagen turnover, angiogenesis, and antifibrosis; therefore, relaxin may also affect orthodontic tooth movement through alterations of the periodontal ligament (PDL), although little is known regarding the relationship between relaxin and human PDL (hPDL) cells. In the present study, we investigated whether hPDL cells contain LGR7 and LGR8, in order to evaluate the effects of relaxin on the expression of collagen typeI (Col-I) and typeIII (Col-III), as well as matrix metalloproteinase 1 (MMP-1) in hPDL cells in vitro. The expressions of LGR7 and LGR8 in hPDL cells were detected using immunocytochemistry and RT-PCR methods. Further, hPDL cells treated with relaxin decreased the release and gene expression of Col-I and increased that of MMP-1 in a dose-dependent manner (p<0.05, one-way ANOVA), whereas the expression of Col-III was not changed. Our results indicated that relaxin modulates collagen metabolism in hPDL cells via the expression of Col-I and MMP-1.

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The purpose of this study was to compare levels of human IL-1β and IL-8 secretion during tooth movement using a nickel-titanium closed coil spring (NTCS) and an elastic c-chain (EC). Data were obtained from twenty healthy orthodontic patients treated with a pre-adjusted edgewise appliance with all first premolars extracted. In each subject, one maxillary canine received continuous force with a NTCS. The opposite maxillary canine received an interrupted force with an EC. Gingival crevicular fluid (GCF) was collected from distal sides of the canines before bracket placement, before canine retraction (baseline), at 24 hours, and at 1 and 2 months after canine retraction. IL-1β and IL-8 levels were measured. The amount of canine movement was measured from the models using the third palatal rugae as the reference point. IL-1β and IL-8 levels at each time point were compared to the baseline by analysis of variance (ANOVA) for repeated measures. A paired t-test was used to determine any significant differences of IL-1β and IL-8 levels between the groups at each time point and to compare the rate of canine movement between groups. The results demonstrated that IL-1β and IL-8 levels in both groups showed a significant elevation at 24 hours, and then declined. IL-1β and IL-8 levels in the NTCS group were significantly higher than the EC group at 24 hours, and 1 and 2 months after force application (p<0.001). The rate of canine retraction in the NTCS group was significantly higher than that of the EC group (p<0.001). In conclusion, the NTCS gave higher rate of canine retraction, which correlates with IL-1β and IL-8 levels.

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There has been an intensive search for many years for chemical agents that could supplement or even supplant patient-dependent mechanical plaque control and thus reduce or prevent oral diseases. The amount of literature relating to the use of chlorhexidine in plaque control is immense; the proof of the agent’s efficacy regarding such a role is beyond dispute. After three decades of use by the dental profession, chlorhexidine is still recognized as the gold standard against which other antiplaque and antigingivitis agents are measured. Chlorhexidine appears to be mainly useful in situations in which oral hygiene is difficult, compromised or impossible. Most research has been concerned with chlorhexidine mouthrinse; however, similar applications could involve chlorhexidine spray, gel, toothpaste and chewing gum. This article reviews the literature on the indications and various modes of delivery of chlorhexidine and provides guidelines on its usage.

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