Reactive oxygen species generation required for autophagy induction during butyrate- or propionate-induced release of damage-associated molecular patterns from dying gingival epithelial Ca9-22 cells.

PURPOSE: Bacterial cells in mature dental plaque produce a high concentration of short-chain fatty acids (SCFAs) such as butyrate and propionate. SCFA-treatment on human gingival epithelial Ca9-22 cells induced cell death. However, the exact mechanism underlying cell death remains unclear. In this study, the relationship between reactive oxygen species (ROS) and autophagy induction during SCFA-induced cell death was examined. METHODS: Human gingival epithelial Ca9-22 cells were treated with butyrate or propionate to induce cell death and the number of dead cells were measured using SYTOX-green dye. A siRNA for ATG5 and N-acetylcysteine (NAC) were used for autophagy reduction and ROS-scavenging, respectively. Release of damage-associated molecular patterns (DAMPs) such as Sin3A-associated protein 130 (SAP130) and high-mobility group box 1 (HMGB1) were detected using western blot. RESULTS: Reducing autophagy significantly suppressed SCFA-induced Ca9-22 cell death. ROS generation was observed upon SCFA treatment, and scavenging ROS with NAC decreased cell death. NAC also reduced the SCFA-induced increase in microtubule-associated protein 1 light chain 3B (LC3B)-I and LC3B-II, and mitigated the release of DAMPs. CONCLUSION: The findings suggest that ROS generation is necessary for autophagy, which is required for SCFA-induced cell death and accompanying DAMP release.

Possible roles of short-chain fatty acids produced by oral bacteria in the development of alveolar osteitis.

PURPOSE: Alveolar osteitis (dry sockets) is a painful condition characterized by a limited immune response. It is typically caused by the removal of blood clots from extracted tooth sockets, which leads to the fermentation of trapped food remnants by oral bacteria in the cavities, producing high concentrations of short-chain fatty acids (SCFAs). This study examined the effects of SCFAs on immunity and bone metabolism. METHODS: Mouse macrophage Raw264.7 cells were treated with oral bacteria supernatants or SCFA mixtures, and inducible nitric oxide synthase (iNOS) levels were determined by western blot. The same cells were treated with SCFA mixtures in the presence of receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoclast-like cells were counted. MC3T3-E1 cells were treated with SCFA mixtures and stained with alizarin red S. RESULTS: Raw264.7 cells treated with oral bacterial culture supernatants of Porphyromonas gingivalis and Fusobacterium nucleatum inhibited lipopolysaccharide (LPS)-induced iNOS production, likely due to SCFA content. SCFA mixtures mimicking these supernatants inhibited the number of RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive cells and MC3T3-E1 cell mineralization. CONCLUSION: These data suggest that SCFAs produced by P. gingivalis and F. nucleatum may reduce the inflammatory response and mildly induce mineralization of the alveolar walls. These results may contribute to the understanding of alveolar osteitis.

Radiological and histochemical study of bone regeneration using the costal cartilage in rats.

PURPOSE: The purpose of this study was to conduct basic research on the possibility of using cartilage tissue for hard-tissue reconstruction and to observe morphological changes in the transition of the cartilage to bone. METHODS: A 4-mm diameter bone defect was created in the right mandibular angle of rats. Cartilage, autologous bone, and artificial bone were grafted into the defect. Computed tomography (CT) was performed to measure the increase in bone volume. Further histological evaluation of the grafted site was performed. RESULTS: At 12 weeks, CT show that bone formation in the costal cartilage group was comparable to that in the autogenous bone group. Histologically, in the artificial bone group, a clear boundary was observed between the existing bone and defect, whereas in the costal cartilage and autologous bone groups, laminar plate bone repair of the defect was observed. CONCLUSION: The findings in this study suggest that bone reconstruction achieved with cartilage grafting is almost equivalent to that with autogenous bone grafting and that bone reconstruction using cartilage is clinically feasible. In future, if regenerated cartilage is successfully applied clinically, bone reconstruction using regenerated cartilage may be feasible.

Porphyromonas gingivalis gingipains potentially affect MUC5AC gene expression and protein levels in respiratory epithelial cells.

Porphyromonas gingivalis (Pg) is a periodontopathic pathogen that may affect MUC5AC-related mucus hypersecretion along airway epithelial cells. Here, we attempted to establish whether Pg virulence factors (lipopolysaccharide, FimA fimbriae, gingipains) affect MUC5AC in immortalized and primary bronchial cells. We report that MUC5AC gene expression and protein levels are affected by Pg culture supernatant, but not by lipopolysaccharide or FimA fimbriae. Cells treated with either Pg single (Kgp or Rgp) or double (Kgp/Rgp) mutants had altered levels of MUC5AC gene expression and protein levels, and MUC5AC staining of double mutant-treated mouse lung cells showed that MUC5AC protein levels were unaffected. Taken together, we propose that Pg gingipains may be the primary virulence factor that influences both MUC5AC gene expression and protein levels.

Cost of establishing a general dentistry department in a small or medium-sized hospital.

To contribute to future dental healthcare policies, this study compiled data on hospital expenses and follow-ups conducted after a hospital dentistry department was established. In addition, the management status and reports on the utility and challenges of establishing a dentistry department were analyzed. The dentistry department was established through fund raising and inaugurated in May 2009. The depreciation period was set at 7 years, and income and expenditure during the 7 years 8 months after opening were compiled. In total, 17.22 million yen was needed for the dentistry department. The average income from dental care was 21.59 million yen per year, and expenditure amounted to 21.54 million yen per year. The findings indicated that a general dentist able to systemically manage patients was essential in a chronic-care hospital. Moreover, the present findings indicate that if general dentistry consultations were performed without excessive investments, after adjusting for personnel expenses, such an initiative would neither yield considerable income nor produce a substantial deficit. Finally, it is imperative to develop staff who are familiar with the costs and management of hospital dentistry and to increase medical fees for consultations with elderly patients.

Bone marrow-derived mesenchymal stem cells enhance bone marrow regeneration in dental extraction sockets.

Bone marrow-derived mesenchymal stem cells (BMMSCs) remain the most widely used source of osteogenic cells in bone tissue engineering research. A cell-based treatment for alveolar ridge augmentation has received attention as an alternative to bone grafting. In the present study, BMMSC transplantation into tooth extraction sockets of C57BL/6J mice was evaluated for alveolar ridge regeneration. The first right maxillary molars were extracted, and then BMMSCs (PDGFRα+ Sca-1+ CD45- TER119- cells) isolated from femoral and tibial bone marrow were immediately transplanted into the extraction sockets. A control group underwent the same procedure except for BMMSC transplantation. Bone formation in the sockets was evaluated using micro-computed tomography and histological and immunohistochemical analyses. At 3 weeks, bone formation in the sockets was more advanced in the experimental group than in the control group. Histological analysis at 6 weeks after transplantation showed that the sockets in the experimental group also contained a greater quantity of bone marrow. Interestingly, socket bone mineral density was lower in the experimental group than in the control group at 6 weeks. These findings suggest that BMMSC transplantation accelerates bone healing and augments bone marrow formation in tooth extraction sockets.

Diverse calcification patterns of ameloblastic fibro-odontoma on radiographic examination.

The occurrence of ameloblastic fibro-odontoma (AFO) in the oral region is unusual and accounts for 1-3% of all odontogenic tumors. AFO presents mixed radiopaque patterns within the lesion with diverse findings; therefore, it is important to compare this tumor with other odontogenic tumors that radiographically present with calcified bodies. Herein, we observed the calcification patterns within the lesion in seven AFO cases (five males, two females; mean age, 8.3 years; age range, 4-13 years). Periapical and panoramic radiographs were obtained from all seven cases. Five cases underwent conventional computed tomography (CT) scanning, and one underwent cone beam CT. Classification of the calcifications primarily involved the following two characteristics on the X-rays: appearance and location of the lesions. All seven cases were located in the molar regions of the mandible in association with impacted teeth. The calcification patterns of these AFOs were mixed or inhomogeneous within the lesion with various findings, including complex odontoma-like calcifications. However, the patterns differed between panoramic radiography and CT in some cases. The radiolucent lesions in AFO demonstrated varying calcification patterns and were associated with impacted teeth on the CT images.(J Oral Sci 58, 533-537, 2016).

An image-guided technique for puncture of the superior temporomandibular joint cavity: clinical comparison with the conventional puncture technique.

OBJECTIVE: The objective of this study was to compare an image-guided puncture technique (IGPT) with conventional puncture technique (CPT) with respect to accuracy of needle entry, maximal mouth opening, and pain in pumping manipulation treatment of internal derangement of the temporomandibular joint (TMJ). STUDY DESIGN: The subjects comprised 178 patients with internal derangement of the TMJ with closed lock. Treatment was provided using CPT in 102 cases and IGPT in 76 cases. Three variables, number of repunctures, maximal mouth opening distance, and pain threshold according to a visual analogue scale, were measured and compared between IGPT and CPT groups. RESULTS: Access to the superior joint cavity was achieved without correcting the puncture point in 97% of patients who underwent IGPT and 82% of patients in the CPT group. Significant differences were seen in 1-week maximal mouth opening and pain threshold between IGPT and CPT groups (P < .05 each) and resetting of the puncture point was significantly less frequent using IGPT compared with CPT (P < .05). CONCLUSIONS: IGPT is effective for pain mitigation and improves mouth opening during the early postoperative period after pumping manipulation treatment.

Evaluation and analysis of formation of bone at the palate in patients with cleft lip and palate after palatoplasty based on computed tomograms and three-dimensional data.

There are various techniques for palatoplasty, but no studies of postoperative osteogenesis at the palatal fissure. In the cranial and maxillofacial region it is thought to develop from the periosteum, so palatoplasty with mucoperiosteal flaps may encourage new bone to form at the fissure. We evaluated the status of osteogenesis in the hard palate after palatoplasty on computed tomograms (CT). We studied 29 patients (22 boys and 7 girls) with unilateral cleft lip and palate who had pushback palatoplasty with the use of CT obtained between May 2003 and March 2007. Age at the time of operation was recorded. The width of the palatal fissure at the first premolar, the first molar, and the maxillary posterior region were measured on coronal CT. The mean (SD) age at the time of palatoplasty was 16 (2) months. The mean (SD) width of the fissure at the first molar was 3.96 (3.1) mm, and bony union was seen in four patients. The width of the fissure was significantly less at the first molar than at the other sites (p = 0.006). The shape of the margin of the fissure was irregular in nearly all patients. The width of the fissure at the first molar became significantly less, suggesting that osteogenesis had occurred. In some patients the height of the fissure differed. Given the results of previous studies, bony regeneration from the periosteum most likely happens together with regeneration from the margins of the fissure.