Abstract Objective To investigate the effects of intro-oral injection of parathyroid hormone (PTH) on tooth extraction wound healing in hyperglycemic rats. Methodology 60 male Sprague-Dawley rats were randomly divided into the normal group (n=30) and DM group (n=30). Type 1 diabetes mellitus (DM) was induced by streptozotocin. After extracting the left first molar of all rats, each group was further divided into 3 subgroups (n=10 per subgroup), receiving the administration of intermittent PTH, continuous PTH and saline (control), respectively. The intermittent-PTH group received intra-oral injection of PTH three times per week for two weeks. A thermosensitive controlled-release hydrogel was synthesized for continuous-PTH administration. The serum chemistry was determined to evaluate the systemic condition. All animals were sacrificed after 14 days. Micro-computed tomography (Micro-CT) and histological analyses were used to evaluate the healing of extraction sockets. Results The level of serum glucose in the DM groups was significantly higher than that in the non-DM groups (p<0.05); the level of serum calcium was similar in all groups (p>0.05). Micro-CT analysis showed that the DM group had a significantly lower alveolar bone trabecular number (Tb.N) and higher trabecular separation (Tb.Sp) than the normal group (p<0.05). The histological analyses showed that no significant difference in the amount of new bone (hard tissue) formation was found between the PTH and non-PTH groups (p>0.05). Conclusions Bone formation in the extraction socket of the type 1 diabetic rats was reduced. PTH did not improve the healing of hard and soft tissues. The different PTH administration regimes (continuous vs. intermittent) had similar effect on tissue healing. These results demonstrated that the metabolic characteristics of the hyperglycemic rats produced a condition that was unable to respond to PTH treatment.
OBJECTIVE: To determine how early musculoskeletal disorders (MSDs) develop in dental professionals and to explore the potential differences among distinct dental specialties. MATERIAL AND METHODS: 271 dental postgraduates majoring in five dental specialties were recruited, i.e., orthodontics, prosthodontics, endodontics, periodontics and alveolar surgery. 254 age-matched non-dental postgraduates served as the control. The standardized Nordic questionnaire on MSDs and a self-report questionnaire regarding correlative factors (only for dental postgraduates) were answered through emails. Reliability of responses was assessed applying test-retest method. RESULTS: The intraclass correlation coefficient of participants' answers ranged from 0.89 to 0.96. Dental postgraduates had significantly higher prevalence of MSDs than the control group, especially at neck, upper back and lower back. In all dental specialties included, high prevalence of MSDs was reported at neck (47.5%-69.8%), shoulders (50.8%-65.1%), lower back (27.1%-51.2%) and upper back (25.6%-46.5%), with lower prevalence at elbows (5.1%-18.6%), hips (3.4%-16.3%) and ankles (5.1%-11.6%). Periodontics students reported the worst MSDs in most body regions except wrists and knees, which were more prevalent for prosthodontic and alveolar surgery students, respectively. Furthermore, year of clinical work, clinical hours per week and desk hours per week were found as risk factors for MSDs, whereas physical exercise and rest between patients as protective factors. CONCLUSIONS: High and specialty-related MSDs afflict dental professionals even since very early stage of careers. Prevention aimed at the specialty-related characteristics and the risk/protective factors revealed in this study should be introduced to dental personnel as early as possible.