Purpose: Calculus removal is essential for periodontal treatment. The scaling is performed using many types of scalers. The main sources of power used in dentistry at present are hand, air and ultrasound. To resolve the problems of these scalers, we developed a vibrating scaler using an electric rotating mass. The purpose of this study was to evaluate the clinical effectiveness of the vibrating scaler in comparison with a hand scaler.

 Methods: This study was approved by the Review Board of Tohoku University Hospital Institution. The subjects were 20 patients with slight or moderate periodontitis. We examined the left and right paired same-name teeth in the same jaw. One tooth was scaled by the vibrating scaler, and the other tooth was scaled by hand.

 Results: Each examination of calculus index showed a score of zero. The total treatment time of the vibrating scaler was slightly shorter than that of the hand scaler. Patients' pain VAS showed a decreasing tendency, but there was no significant difference in the doctor's fatigue VAS between the two groups. Though we found no difference between the two groups, PPD and BOP showed a significant decrease. We found a significant decrease only on GI at one week using the vibrating scaler. There was no difference between the two groups in the number of bacteria.

 Conclusion: These results indicated that the vibrating scaler had an equal ability to remove calculus as the hand scaler.

 Purpose: Although many properties are required for root canal sealer, no sealer satisfies all of them at present. We aimed to develop a novel root canal sealer with ideal properties, such as high capacity of sealing and removability, ease of use, and high biocompatibility. In the present study, newly developed bioactive glass based root canal sealer (BG sealer) and zinc oxide non-eugenol based sealer (NE-Z sealer) were histopathologically evaluated by means of a rat model for pulpectomy and root canal obturation.

 Method: Distal root canals of mandibular first molars of post-natal 7-week-old male Wistar rats were shaped and prepared. After drying with paper point following root canal irrigation with EDTA solution, sodium hypochlorite solution, and saline, canals were filled with either BG sealer or NE-Z sealer. After 1 and 3 weeks, mandibles were dissected, serial paraffin sections were prepared, and then periapical tissues were examined histopathologically.

 Results: One week after obturation, apparent inflammatory cell infiltration was observed in periapical tissues of both groups, and the inflammatory response decreased at 3 weeks after obturation. Next, the width of periapical alveolar bone resorption area and the thickness of cementum at the root apex were analyzed. No significant difference of periapical alveolar bone resorption area was observed in both groups at 1 and 3 weeks, whereas the width of the area significantly reduced from 1 week to 3 weeks when canals were filled with BG sealer. Cementum in the periapical region of the BG sealer group was significantly thicker than that in the NE-Z sealer group. The thickness of cementum in the BG sealer group significantly increased from 1 week to 3 weeks, but not in the NE-Z sealer group.

 Conclusion: The present in vivo results from the rat model suggest that the newly developed BG sealer is biocompatible with periapical tissues.

 Purpose: When mechanical stress is applied to bone, the stress is sensed by osteocytes, which act as mechanosensors and translate the stress into biological signals. The signals are then transmitted to osteoblasts and osteoclasts by the osteocyte network. These signals regulate the actions of osteoblasts and osteoclasts, and thus contribute to the regulation of bone deposition and absorption. However, the detailed functions of osteocytes are poorly understood. Therefore, the purpose of this study was to isolate osteocytes from the calvaria of newborn rats and examine whether they retain their functions in in vitro cultures.

 Methods: Soft tissue and the periosteum were removed from the calvaria of 3-day-old newborn rats. The calvaria were dipped in 70% ethanol for 15 seconds to kill most of the cells in the superficial layer, before being cut into several pieces. Osteocytes were isolated from the calvaria using collagenase solution and ethylenediaminetetraacetic acid solution. The isolated cells were cultured and then subjected to alkaline phosphatase (ALP) staining. The expression of E11/gp38, dentin matrix protein-1 (DMP-1), sclerostin, and fibroblast growth factor 23 (FGF23) in the cultured cells was analyzed using the real-time quantitative polymerase chain reaction.

 Results: Osteocyte-like cells, which had dendritic processes, were present in the isolated cell cultures, and most of the cells were negative for ALP. E11/gp38, DMP-1, sclerostin, and FGF23 expression were detected in the cultured cells after 7 days, and the mRNA expression levels of these molecules had increased after 14 days.

 Conclusion: Cultured cells that were isolated from calvaria expressed osteocyte-like phenotypes. Our findings suggest that the culture system employed in the present study is useful for analyzing osteocyte functions.

 Purpose: We performed a randomized control study on the effects of dentifrice containing low doses of mastic essential oil and fluvic acid against periodontal disease.

 Methods: Test dentifrice A containing a low dose of mastic essential oil, test dentifrice B containing mastic essential oil and fluvic acid, and placebo were used in a clinical test of 30 patients with periodontal disease. The test dentifrices were assigned randomly and used for 12 weeks. Periodontal condition was checked by various clinical parameters at the start of using the dentifrice, and at 4 and 12 weeks after testing. Bacterial examination by using the invader PCR method against Porphyromonas gingivalis was carried out both at the start and at 12 weeks after testing. Statistical analysis was done using Wilcoxon's rank sum test, Chi-squared test and analysis of variance.

 Results: The placebo and test dentifrices A and B showed a statistically significant improvement under almost all clinical conditions after 12 weeks of use. As to plaque accumulation, test dentifrice A showed statistically significant superiority compared with placebo (p<0.05) at 12 weeks. Both test dentifrices A and B showed improvement regarding the discharge of pus compared with placebo (p<0.05) at 4 weeks. At 4 weeks test dentifrices A and B showed statistically significant improvement concerning halitosis compared with placebo (p<0.01, p<0.001). On the contrary, bacterial analysis showed no statistically significant improvement.

 Conclusion: The results of this study suggest that dentifrices containing low doses of mastic essential oil and fluvic acid might be useful clinically even without microbiological proof.

 Purpose: The purpose of this study was to evaluate the gloss of composite resin blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) polished by three different polishing systems.

 Materials and Methods: The surfaces of three composite resin blocks, i.e., Katana Avencia Block, CeraSmart, and Shofu Block HC, were wet-ground with #100 SiC paper, and the gloss of the ground surfaces was measured. The surfaces were then polished using one of the three different polishing systems that we selected for this study: CeramDia M and CeramDia SF (Ce), Pre Shine and Dia Shine (Pr), and Silicone points M2 and Compomaster (Si). The gloss of the polished surfaces was measured, and the obtained data was statistically analyzed. In addition, the gloss of the polished surfaces was visually inspected by twenty dentists in accordance with JIS Z 8723. The polished surfaces were also observed using a scanning electron microscope (SEM).

 Results: Katana Avencia Block showed a significantly higher gloss than CeraSmart and Shofu Block HC when polished by the Pr or Si system (p<0.05). Regarding the polishing systems, the Si system provided the highest gloss when used for any of the composite resin blocks (p<0.05). Upon visual inspection, the highest gloss surface was confirmed for the Katana Avencia Blocks when polished with the Si system. SEM observation revealed that the Katana Avencia Block was densely packed with nanofillers, and the fillers observed in the Shofu Block HC varied in size from small to large.

 Conclusions: The gloss of the composite resins was significantly affected by both the composite resin material and the polishing system (p<0.05). The highest gloss was exhibited in the Katana Avencia Block for the composite resin, and by Silicone points M2/Compomaster for the polishing system.

 Purpose: This study examined the bonding performance of universal adhesives to acid eroded enamel substrates.

 Methods: Three universal adhesives were used: All-Bond Universal (AB), Adhese Universal (AU), and Scotchbond Universal Adhesive (SU). Bovine incisors were sectioned to expose the flattened enamel area, and ground on wet 600-grit Sic paper. One group of ten specimens was treated with lactic acid solution (pH 4.75) for ten minutes (10-min group) twice a day. These procedures were done throughout the 7-day test period (7-day group). Before applying adhesives, adherent enamel surfaces were treated with or without phosphoric acid. Then, single-step self-etch adhesive was applied and light cured, and resin composite was condensed into a mold and polymerized. Ten samples per test group were stored in distilled water at 37℃ for 24h, the specimens were subjected to thermal cycling (TC) for 10,000 or 30,000 times, then bond strengths were measured with a crosshead speed of 1.0 mm/min.

 Results: The results of the enamel bond strength of the 10-min group showed no significant differences compared to the control group. On the other hand, significantly lower bond strengths were obtained for the 7-day group compared with the 10-min group for SU without phosphoric acid etching. After thermal cycling, there were no significant differences between the with etching group and the without etching group for all the materials tested.

 Conclusion: Within the limitations of this in vitro study, it can be concluded that the acidic erosion of the enamel substrate affected the bonding performance of the self-etch adhesive. Enamel bond strength was increased when phosphoric acid was employed, and stable enamel bond strengths were obtained after thermal cycling.

 Purpose: This study aimed to assess the generation of torque and apical force during root canal preparation with nickel-titanium instruments rotated in torque-sensitive and time-dependent movements.

 Methods: An automated root canal instrumentation and force/torque analyzing device was custom-designed to prepare simulated canals in different motions and monitor the apical force and torque. The device consisted of (1) a root canal shaping motor designed to rotate in different motions; (2) a motorized test stand to automatically move the handpiece of the motor upward or downward, and (3) a torque/force measuring unit connected with a simulated resin canal. The following three experimental groups were set: (1) torque-sensitive reciprocal rotation with torque-sensitive vertical movement (TqR); (2) time-dependent reciprocal rotation with time-dependent vertical movement (TmR); and (3) continuous rotation with time-dependent vertical movement (CR). In the TqR mode, the motor was programmed to detect torque during rotation (300 rpm), and when the predetermined torque was detected, the motor reversed its rotation 90 degrees to the non-cutting (counterclockwise) direction and then 180 degrees to the cutting (clockwise) direction. A torque-sensitive vertical movement (downward movement for 2 seconds and upward for 1 second (10 mm/min) and, upon detection of the predetermined torque, downward for 0.25 second followed by upward for 3 seconds) was installed. In the TmR mode, the file was reciprocally rotated 90 degrees to the non-cutting direction and 180 degrees to the cutting rotation at 300 rpm. In the TmR and CR modes, the handpiece was moved downward for 2 seconds and upward for 1 second (10 mm/min). Simulated resin canal models with a straight canal (n=7 in each group) were instrumented with ProTaper Next X2 rotary files, and the torque and apical force were measured. The maximum apical force and torque values were statistically analyzed using Kruskal-Wallis and Mann-Whitney U-test with Bonferroni correction (α=0.05).

 Results: There were no statistically significant differences among all groups in maximum apical force values, or maximum torque values in the counterclockwise direction. However, Group TqR showed significantly smaller maximum torque values in the clockwise direction compared to Groups TmR and CR (p<0.05).

 Conclusion: Under the present experimental conditions, torque-sensitive reciprocal rotation, in combination with torque-sensitive vertical movement, generated significantly smaller maximum torque values when compared with time-dependent reciprocal rotation and continuous rotation.

 Purpose: EndoREZ (ULTRADENT JAPAN) is a methacrylate resin-based root canal sealer, which is hydrophilic and permeates into dentinal tubules. EndoREZ is designed to bond to resin-coated gutta-percha (EndoREZ point, ULTRADENT JAPAN) for creating adhesion between intraradicular dentin and the root filling. The aim of this study was to evaluate the healing of periapical tissue after root canal filling with EndoREZ in rat molars.

 Methods: EndoREZ was used as a test material. Wistar rats aged 6 weeks were subjected to general anesthesia. Coronal access to the pulp chamber of the maxillary first molar was gained under a microscope. The root pulps were removed using a #10 H-file, and size up to #20 Ni-Ti rotary file. After irrigation, the root canal was filling by the single point method. Zinc oxide-eugenol root canal sealer (Nippon Shika Yakuhin; CS-EN) used as a control material. After 2 and 4 weeks, the animals were sacrificed, and the bones with teeth were removed and fixed in 4% paraformaldehyde. After demineralization with 10% EDTA, the tissues were embedded in paraffin, then 6-μm-thick longitudinal sections were stained with hematoxylin and eosin, and examined under a light microscope.

 Results: In the experimental group with root canal filling with EndoREZ, hard tissue-like structures were observed in the periapical tissues in 4 samples at 2 weeks, and in all samples at 4 weeks. Extended inflammation of periapical tissues was hardly observed. At 2 weeks after root canal filling, there was a significant difference in the parameters of newly formed mineralized tissue, periodontal ligament thickness, and extension of inflammatory reaction (p<0.05). However, at 4 weeks after root canal filling, there was a significant difference only in the newly formed mineralized formed tissue compared with the controls (p<0.05).

 Conclusion: It was suggested that EndoREZ, a methacrylate resin-based root canal sealer, results in osseous healing of periapical tissue with almost no inflammation in rat immature teeth.