Purpose: This study investigated the effect of low-level Nd: YAG laser irradiation on human gingival fibroblasts (Gin-1). We assayed cell proliferation, cell migration, LDH activity, FGF-2, TGF-β1, and HSP47 expression.

 Methods: Gin-1 was irradiated for 30 s at a distance of 20 mm at three laser outputs: 0.5 W (90 μs/pulse, 100 mJ/s, 5 pps), 1.0 W (90 μs/pulse, 200 mJ/s, 5 pps), and 2.0 W (90 μs/pulse, 400 mJ/s, 5 pps). Cell proliferation was also measured 1, 3, and 5 d after irradiation using an improved MTT method. Next, an ELISA was performed on the culture supernatants at the same time points to measure FGF-2 and TGF-β1 expression at 1, 2, and 3 d. Cell migration was assayed at 5 and 24 h and LDH was employed to determine cell cytotoxicity at 3 h, 1 d, and 3 d, post irradiation. For each time point, we compared the results of a scratch assay between the control and irradiation group for analysis of cell migration. After 3 h of irradiation, we performed an immunofluorescence assay for HSP47.

 Results: Compared with that in the non-irradiated control, cell proliferation was significantly higher in the groups exposed to 100, 200, and 400 mJ/s of radiation after 3 d, and to 200 and 400 mJ/s after 5 d. There was an increase in FGF-2 expression in every experimental group at 1 and 2 d. However, at 3 d, only the 100 mJ/s group continued to show an increase in FGF-2 expression. TGF-β1 expression increased significantly in the 200 mJ/s group compared to the control at 1 and 2 d. At 3 d, both the 100 mJ/s and 200 mJ/s groups showed a significant increase in TGF-β1 expression compared with the control. With regard to the scratch assay, cells in the 200 mJ/s group showed significantly higher migration than the control at 5 h. At 24 h, both the 200 mJ/s and 400 mJ/s groups also showed significantly higher migration than the control. No significant changes were observed in LDH levels in any of the irradiated groups. Furthermore, HSP47 expression was observed between the control and all laser irradiation groups.

 Conclusion: The Nd: YAG irradiation conditions reported here harmlessly promote Gin-1 activity.

 Purpose: Resin cements utilizing universal adhesives have been marketed in order to simplify clinical procedures and overcome the technique sensitivity of multiple-step resin cement systems. However, the influence of light irradiation on the bonding performance of resin cement is not known. The purpose of this study was to monitor the chronological changes of dentin bond strength of resin cement using a universal adhesive.

 Methods: Two dual-cure resin-based cements, a combination of universal adhesive/resin cement (Scotchbond Universal/RelyX Ultimate Resin Cement, RXU; 3M ESPE) and conventional type resin cement (Clearfil Esthetic Cement, CEC; Kuraray Noritake Dental), were used. Bovine dentin was wet-ground with #600 SiC paper. Resin columns (4 mm in diameter, 2 mm in height) were cemented and light-irradiated with the power density of 600 mW/cm² or not irradiated (chemical-cured). The shear bond strengths of 10 specimens per group were measured at a cross-head speed of 1.0 mm/min after 15 min, 1, 6, 12, and 24 h storage in a chamber at 37±1°C, 90±5 RH%. Statistical analysis was done to test for the presence of a significant difference between the mean bond strength at each test time at a significance level of 0.05.

 Results: The dentin bond strength increased with prolonged specimen storage time. When the specimens were light-irradiated, higher bond strengths were obtained compared to those specimens without irradiation. When the specimens were without light irradiation, dentin-cement interface failures were observed for RXU and CEC. When the specimens were light irradiated, cohesive failures within resin and dentin were observed for RXU, and dentin-cement interface failures were observed for CEC.

 Conclusions: From the results of this study, it was concluded that the chronological change in the dentin bond strength of resin cement was affected by the presence or absence of light irradiation of the specimen. Light irradiation might be necessary to achieve greater dentin bond strength, even in materials with a dual-cured setting reaction.

 Purpose: We previously analyzed clinical examinations and first diagnosis (pre-treatment diagnosis) for new patients at the Clinic of Operative Dentistry and Endodontics in Kyushu Dental University Hospital. In this study, to clarify the current status of endodontics more accurately, we analyzed the relationship between symptoms and treatment contents from the perspective of definitive diagnosis for new patients at the department.

 Methods: Of 651 patients who first visited our clinic and started dental treatment during a 3-year period (2011-2013), we extracted 382 patients (439 teeth) related to pulpitis (Pul) and apical periodontitis (Per) as the subjects of this study, and surveyed the contents of diagnosis, age, tooth kind, referral rate from general practitioners, and contents of treatment (endodontic treatment, re-treatment, or tooth extraction).

 Results: Regarding the rate of Pul and Per, a significant difference was not found between the first and definitive diagnosis. By age, the largest group of patients with Pul and Per was patients in their twenties (26.6%) and sixties (21.3%), respectively. By tooth kind, the largest group of Pul and Per was mandibular molars. The referral rate from other clinics for the purpose of treatment for Pul and Per was more than 50%. The re-treatment ratio of Per was higher than that of Pul.

 Conclusion: These results indicate that the university hospital plays an important role as a secondary/tertiary medical institution for endodontic treatment, which is one of the most common treatments in private dental clinics. Also, reduction of the re-treatment rate in endodontic therapy is an urgent issue to improve the level of dentistry in Japan.

 Purpose: Beta-tricalcium phosphate (β-TCP) exhibits biocompatibility and osteoconductivity and has been used clinically as a bone graft material. However, conventional β-TCP degrades slowly, with residual material frequently inducing aberrant healing. We therefore developed a collagen scaffold containing β-TCP nanoparticles by applying nanoscale dispersing technology. When the nano-β-TCP/collagen scaffold was implanted into rat cranial bone, its degradation and bone augmentation were remarkable when compared with collagen sponge. Accordingly, we evaluated the bone-forming effects of nano-β-TCP/collagen scaffold on extraction sockets in dogs.

 Methods: β-TCP powder (average particle size: 2.3 μm) was pulverized into nanoscale particles and dispersed into distilled water along with the surfactant sodium cholate (0.2 wt%). Collagen sponge was immersed in a dispersion (1 wt%) of β-TCP nanoparticles. This was followed by rinsing and freeze-drying to yield the nano-β-TCP/collagen scaffold. The surface of the scaffold was characterized by SEM. Subsequently, the extraction socket of a maxillary first premolar was filled with nano-β-TCP/collagen scaffold in the experimental group, while collagen sponge was applied to the socket in the control group. Radiographic images of the socket were then obtained at baseline, and at 1, 3 and 5 weeks after surgery. Histological observations were performed at 2 and 5 weeks.

 Results: SEM images showed nanosized (approx. 100 nm) β-TCP particles attached to the fibers of collagen sponge. The interconnected spaces within the collagen sponge were not filled with β-TCP particles. In the experimental group, the extraction socket showed increased radiopacity when compared with the control group. Histological observation at 2 weeks revealed that new bone was present in the socket in the experimental group. In addition, ingrowth of cells and blood vessels was detected in the nano-β-TCP/collagen scaffold. In contrast, only slight new bone growth was seen in the control group. At 5 weeks in the experimental group, the scaffold had disappeared and the extraction socket was fully filled with new bone. In the control group, although new bone was detected, connective tissue and residual collagen sponge were also observed in part of the extraction socket. Newly formed bone area in the experimental group (25.1%) was significantly greater when compared with the control group (7.6%). Residual material area in the experimental group (59.1%) was significantly less when compared with the control group (81.2%).

 Conclusion: Nano-β-TCP/collagen scaffold exhibited high biocompatibility and degradability. New bone formation in tooth extraction sockets of dogs was facilitated by implantation of nano-β-TCP/collagen scaffold.

 Purpose: Fluoride varnishes are commonly used for the prevention of caries in Western countries. The purpose of this study was to observe the remaining materials after removing the materials being used, and to evaluate the effect of fluoride varnish on inhibition of demineralization and uptake of fluorine on the root dentin surface using an automatic pH-cycling system.

 Methods: Two different fluoride varnishes (CTX2 Varnish (FVC) and White Fluoride Varnish (FVB) ) and one glass-ionomer cement (Fuji Ⅸ_GP FAST CAPSULE (FN) ) were used as materials. Nine extracted human molars were used. One tooth out of nine was divided into three specimens (10×5 mm, each). Either FVC, FVB or FN was applied on the root surface. Half of the applied material was removed from the root surface after 24 hours storage in 37°C water. The surface of the specimen before and after removing materials was analyzed by SEM, EDS and In-air μPIXE/PIGE. Using the remaining eight teeth, each tooth was divided into four specimens. Either FVC, FVB or FN was applied on the specimens. Untreated specimens were used as controls. The applied material was removed from the surface as mentioned above after 24 hours storage in 37°C water. 200 μm-thick single sections were obtained from each specimen. The entire surface of the specimen, except the outer surface, was covered with a wax. The pH-cycling (pH 7.0-4.5) was carried out for four weeks. A transverse microradiograph (TMR) image of each specimen was taken before, and after 2 weeks and 4 weeks of pH-cycling. Integrated mineral loss (IML) close to CEJ was calculated from the TMR images. After the whole pH-cycling, the fluorine concentration in each specimen was evaluated using in-air μPIXE/PIGE.

 Results: After removing fluoride varnishes from the dentin surface, small amounts of the applied materials were found to be remaining. At 2 weeks after pH-cycling, all three experimental groups showed significantly lower values of ΔIML than the control group. At 4 weeks after pH-cycling, FVB and FN showed significantly lower values of ΔIML than the control group. The fluorine concentration of specimens showed no significant differences among the four groups, but three applied materials tended to provide fluorine to the dentin surface.

 Conclusion: After removing the applied materials from the dentin surface, small amounts of the materials were found to be remaining. Fluoride varnishes showed an effect of inhibiting demineralization of the root surface and exhibited uptake of fluoride similar to those of cement.

 Purpose: Mineral trioxide aggregate (MTA) is known to promote hard tissue formation by pulp cells in direct pulp capping. However, little is known about the reparative process of mechanically direct capping with MTA. Our previous study provided direct evidence that the canonical Wnt/β-catenin pathway is involved in the regulation of odontoblast differentiation and dentin formation. In the present study, dentinogenesis after pulp capping with MTA was examined by continuous observations and evaluated by immunohistological analyses with a Wnt10a antibody.

 Methods: An occlusal cavity was prepared as exposed pulp in the maxillary molar teeth of 20 Sprague-Dawley rats. Then, MTA was placed on the exposed pulp. All cavities were restored with composite. After 5, 7, 10, or 21 days, the animals were sacrificed, and the maxillary bones were dissected, fixed with 10% paraformaldehyde for 24 hours, and processed to prepare the samples. Then, the samples were histologically observed after hematoxylin and eosin staining or immunoperoxidase staining using Wnt10a and dentin sialophosphoprotein.

 Results: On hematoxylin and eosin staining, the MTA-treated groups showed significantly accentuated vascular proliferation and dentin-like hard tissue formation with an odontoblastic layer. In the 21-day specimens, there was a complete dentin bridge obliterating the exposed pulp. Wnt10a immunoreactivity was observed in the matrix, just beneath the odontoblast-like layer, at 7 days after MTA capping. In addition, dentin sialophosphoprotein immunoreactivity was observed in the odontoblast-like cells.

 Conclusions: In the present immunohistological study on direct pulp capping with MTA, vascular proliferation and the differentiation of odontoblast-like cells for the formation of hard tissue were observed in pulp tissue. Furthermore, it was suggested that the Wnt signaling pathway is involved in odontoblastic differentiation in direct pulp capping with MTA.