Primary cultures of chick osteocytes retain functional gap junctions between osteocytes and between osteocytes and osteoblasts

The inaccessibility of osteocytes due to their embedment in the calcified bone matrix in vivo has precluded direct demonstration that osteocytes use gap junctions as a means of intercellular communication. In this article, we report successfully isolating primary cultures of osteocytes from chick calvaria, and, using anti-connexin 43 immunocytochemistry, demonstrate gap junction distribution to be comparable to that found in vivo. Next, we demonstrate the functionality of the gap junctions by (1) dye coupling studies that showed the spread of microinjected Lucifer Yellow from osteoblast to osteocyte and between adjacent osteocytes and (2) analysis of fluorescence replacement after photobleaching (FRAP), in which photobleaching of cells loaded with a membrane-permeable dye resulted in rapid recovery of fluorescence into the photobleached osteocyte, within 5 min postbleaching. This FRAP effect did not occur when cells were treated with a gap junction blocker (18 alpha-glycyrrhetinic acid), but replacement of fluorescence into the photobleached cell resumed when it was removed. These studies demonstrate that gap junctions are responsible for intercellular communication between adjacent osteocytes and between osteoblasts and osteocytes. This role is consistent with the ability of osteocytes to respond to and transmit signals over long distances while embedded in a calcified matrix. </p

Early loss of primary teeth among children in Thamar city, Yemen

Objectives: The premature loss of primary teeth is a potential risk factor for poor arch length development. Adequate arch length is important to the progression of the permanent teeth. Poor arch length can lead to crowding, ectopic eruption, or impaction of these teeth. This study is designed to assess the prevalence of premature loss of primary teeth in the 5-10-year-old age group. Materials and Methods: The study group included 185 children, that is, 91 boys and 94 girls. The dental examination was conducted by an experienced examiner under sufficient artificial light. Data including patient age and missing teeth were collected. Descriptive statistics were applied for data analysis, and from the results, Chi-square tests were used at a level of significance of 5% (P < 0.05). Results: We observed a 40.54% prevalence of premature loss of primary teeth with no statistically significant difference between genders. The lower left primary second molar was the most commonly absent tooth in the dental arch (13.5%). Conclusion: The status of premature loss of primary teeth was high in the study group. Implementation of efficient educational and preventive programs to promote oral health would help children maintain a healthy primary dentition and eventually prevent the disturbances in the future development of normal occlusion. Early detection and management of the space problems associated with the early loss of primary teeth would help in reducing malocclusion problems

The Relationship between Number of Natural Teeth and Chewing Qat Habit among Adult Yemeni People in Sana'a : A Pilot Study

Aims and Objectives: Several studies have reported associations between the habit of chewing qat and the deterioration of periodontal health among adults in Yemen; however, qat's effect on the number of teeth has not yet been evaluated. The purpose of this observational study was to examine the relationship between the number of natural teeth and qat-chewing status among Yemeni participants. Materials and Methods: The participants were interviewed with a structured questionnaire by a researcher on the day of the dental check-up. The surveyed items were age. sex. chewing-qat status (nonchewer: current chewer. nonsmoker; current chewer and smoker: current chewer. ex-smoker: ex-chewer. never smoked; ex-chewer and smoker). The dental examination was conducted with dental mirrors by a single examiner under sufficient artificial light. A linear regression was performed. stratified by sex, with the number of natural teeth as the dependent variable and with age and qat status as independent variables using SAS/STAT software. Results: Results show that age was a significant factor for both males and females having few natural teeth. Females had a higher tooth loss than males. The habit of chewing qat did not affect the number of natural teeth for both males and females. In males, a small, but not significant, relationship between chewing-qat status and the number of natural teeth was found. All smokers were qat chewers. Conclusion: This study highlights for the first time the relationship between having fewer teeth and the habit of chewing qat and provides useful findings for dental health workers to advise people about the benefits of cessation of both qat chewing and smoking.Peer reviewe