Interleukin-1ß induces human cementoblasts to support osteoclastogenesis.

Injury of the periodontium followed by inflammatory response often leads to root resorption. Resorption is accomplished by osteoclasts and their generation may depend on an interaction with the cells in direct contact with the root, the cementoblasts. Our study aimed to investigate the role of human cementoblasts in the formation of osteoclasts and the effect of interleukin (IL)-1ß hereupon. Extracted teeth from healthy volunteers were subjected to sequential digestion by type I collagenase and trypsin. The effect of enzymatic digestion on the presence of cells on the root surface was analyzed by histology. Gene expression of primary human cementoblasts (pHCB) was compared with a human cementoblast cell line (HCEM). The pHCBs were analyzed for their expression of IL-1 receptors as well as of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG). In a co-culture system consisting of osteoclast precursors (blood monocytes) and pHCBs, the formation of osteoclasts and their resorptive activity was assessed by osteo-assay and ivory slices. The cells obtained after a 120 min enzyme digestion expressed the highest level of bone sialoprotein, similar to that of HCEM. This fraction of isolated cells also shared a similar expression pattern of IL-1 receptors (IL1-R1 and IL1-R2). Treatment with IL-1ß potently upregulated RANKL expression but not of OPG. pHCBs were shown to induce the formation of functional osteoclasts. This capacity was significantly stimulated by pretreating the pHCBs with IL-1ß prior to their co-culture with human blood monocytes. Our study demonstrated that cementoblasts have the capacity to induce osteoclastogenesis, a capacity strongly promoted by IL-1ß. These results may explain why osteoclasts can be formed next to the root of teeth.

Dental Student Hand Hygiene Decreased With Increased Clinical Experience.

OBJECTIVE: To investigate the effectiveness, related knowledge, attitudes, and practices of hand hygiene (HH) among dental students with different levels of clinical experience. DESIGN: This was a cross-sectional analytical study. Bacterial samples on the participants' hands were obtained using a swab technique before and after handwashing, for oral surgical procedures. After culturing, the colony-forming units were counted. Self-reported questionnaires reflecting the knowledge, attitudes, and practices related to HH were completed by the participants. SETTING: This study was performed in a primary oral health care institution, Faculty of Dentistry, Chulalongkorn University (Bangkok, Thailand). Bacterial samples and self-reported questionnaires were collected in the Department of Oral and Maxillofacial Surgery. Bacterial culture was performed in the Department of Microbiology. PARTICIPANTS: The 120 participants comprised first, second, third-year clinical training students (CTs), and postgraduate dental students (PGs) (32, 34, 30, and 24 participants, respectively). RESULTS: More than 99% of the bacteria were eliminated from the participants' hands after handwashing. Significantly higher numbers of bacteria were recovered from the hands of the PGs compared with those of the CTs, and the hands of the third-year CTs compared with those of the first-year CTs (p < 0.001), after HH. The first-year CTs had the highest attitude scores, whereas the PGs had the lowest practice scores. The knowledge scores were similar in all groups. CONCLUSION: HH effectiveness, attitudes, and practices of dental students decreased as students gained more clinical experience, whereas knowledge did not. Our results suggest that HH instruction should be given throughout the duration of dental students' education.