Purpose: The concept of minimal intervention has become popular and the importance of pulp conservation is now recognized. However, a standard for the removal of dental caries has not yet been determined. In the present study, we qualitatively and quantitatively investigated the effect of Er: YAG laser irradiation on residual bacteria after removal of softened dentin. Methods: Fifty-seven teeth which needed caries treatment were studied. After removing the caries with Caries Detector until the dentin was stained light pink, Er: YAG laser was irradiated to the cavity and the dentin sample was collected. In the control specimens, the dentin specimen was collected without Er: YAG laser irradiation. Then, the number and species of bacteria collected from the sample were evaluated. Some samples were subjected to confocal laser microscopic observation. Results: No patients complained of any clinical symptoms in either the experimental group or control group. In the control group, residual bacteria were detected in 69% of samples, whereas in the Er: YAG laser irradiated group the detection rate was only 43 % (p<0.05). The number of bacteria detected in the experimental samples was significantly less than that in the control samples (p<0.05). Confocal microscopic observation showed a similar tendency to these results. We could not find clear differences between the control and experimental groups concerning the species of detected bacteria. Conclusion: Er: YAG laser irradiation after removal of caries effectively reduced residual bacteria in the cavity.

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Purpose: To investigate in vivo responses of macrophages and dendritic cells to mineral trioxide aggregate (MTA), the expression of molecules associated with macrophages/dendritic cells was examined in MTA-implanted rat subcutaneous tissue by means of immunohistochemistry and quantitative gene expression analysis. Methods: Silicone tubes containing mixed MTA (ProRoot MTA) or a calcium hydroxide-based cement (Life) were subcutaneously implanted into the back of male Wistar rats. Solid silicone rods of similar size served as controls. At 14 days after the implantation, connective tissue surrounding the implants was retrieved and processed for double immunoperoxidase staining using ED1 (reactive to macrophages and dendritic cells) and OX6 (reactive to major histocompatibility complex class II molecules), and the number of ED1+/OX6+ and ED1+/OX6- cells was enumerated. Real-time polymerase chain reaction (PCR) analysis was also carried out to quantify the mRNA expression levels of CD163 (a marker for tissue repair (M2) macrophages) and CD34 (expressed in endothelial cells and subpopulation of dermal dendritic cells) in the subcutaneous connective tissue. Statistical differences were analyzed by the Mann-Whitney U-test with Bonferroni correction. Results: In the MTA-implanted tissue, ED1+/OX6+ cells showed a significantly higher density compared with the other groups (p<0.05), and ED1+/OX6- cells showed a significantly higher density compared with the Life-implanted tissue (p<0.05). The expression levels of CD34 and CD163 mRNAs in the MTA-implanted tissue were significantly higher than those in the Life-implanted and control tissues (p<0.05). Conclusion: In the subcutaneous connective tissue of rats, MTA induced the infiltration of a significantly higher density of CD68+ cell subpopulations (ED1+/OX6+ and ED1+/OX6- cells) and significantly higher levels of CD34 and CD163 mRNAs, as compared with Life. These results suggest that wound healing/tissue repair processes involving macrophages participate in the biological tissue reaction to MTA.

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Purpose: We have developed a novel dentin desensitizing treatment consisting of sequential application of surface reaction type pre-reacted glass-ionomer fine powder (S-PRG powder, 0.8 μm average particle size) and 13% polyacrylic acid. The purpose of this study was to assess the treatment in terms of dentinal tubule occluding potential and acid resistance of underlying dentin by using SEM and transversal microradiography (TMR). Methods: Dentin specimens were cut from bovine roots, and test surfaces were smoothed using 2,000-grit waterproof abrasive paper and the dentinal tubules were opened. The specimens were then divided into S-PRG, MS coat and control (no treatment) groups. In the S-PRG group, a micro applicator was dipped in deionized water and dredged with the S-PRG powder. The S-PRG powder was then applied on the simulated hypersensitive dentin area with opened dentinal tubules by rubbing for 15 seconds. Then, 13 % polyacrylic acid was applied for five seconds. The MS coat was applied in accordance with the manufacturer's instructions. After immersing in deionized water for 24 hours, dentinal tubule occlusion in the surface and torn surface was observed by SEM. The acid resistance test was performed by exposing the test surface to pH 5.0 acetic acid gel for 7 days. After the acid resistance test, SEM observation was done in the same way, and the acid resistance of the underlying dentin was evaluated by TMR. The integrated mineral loss (IML) was measured using the dedicated software TMR 2000. Results: The control group with no treatment revealed opened dentinal tubules, simulating a hypersensitive dentin surface. Dentin surfaces treated with S-PRG were completely covered with thin films and plugs that may have represented the reaction products of S-PRG filler and polyacrylic acid, even after the acid resistance test. The plugs penetrated to a depth of approximately 20 μm. In the MS group, however, some dentinal tubules were opened even before the acid resistance test, and more tubules were opened after the test. TMR showed that the S-PRG group demonstrated lesion profiles with high mineral volume %, whereas the control and MS groups showed severely demineralized lesions. The IML of the S-PRG group was significantly lower than that of the other two groups (p<0.05). Conclusion: These results showed that the novel treatment with S-PRG powder and polyacrylic acid caused the occlusion of dentinal tubules and prevented the demineralization of underlying dentin, suggesting that the treatment may be effective for dentin desensitization.

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Purpose: We developed novel silane coupling agents with hydrophobic groups to improve the water resistance of the coupling layer, and reported that these compounds showed no significant decrease compared with 3-methacryloylxytrimethoxysilane (3-MPS) alone in tensile bond strength after long-term water storage. The aim of this study was to investigate the cytotoxicity of the silane coupling agents nonafluorohexyltrimethoxysilane (4F) and 3- (4-methacryloyloxyphenyl) propyltrimethoxysilane (p-MBS). Methods: Glass plates were modified with 50 mmol/l solutions of 3-MPS, 4F and p-MBS, and then sterilized with ethylene oxide gas. The modified glass plates were immersed in cell culture medium (MO5) for 24 hours at 37℃ in a 5% CO₂ atmosphere to measure the toxicity of the extraction. The extracted medium (100%) was diluted with the MO5 into ten different concentrations (0.5-50%). Chinese Hamster fibroblast (V79) suspension (0.5 ml: 100 cells/ml) was seeded on a 24-well cell culture plate and pre-incubated for 6 hours at 37℃ in a 5% CO₂ atmosphere. After the pre-incubation, 0.5 ml of each concentration of the silane extracts was poured onto the cell culture. After cultivation for 6 days, the cells were stained with 0.1% methylene blue solution and colonies of more than 50 cells were counted. The cytotoxicity of the silane coupling agents was evaluated according to the 50% inhibitory concentration (IC₅₀). Results: The IC₅₀ values of 3-MPS, 4F, and p-MBS were all over 100%. Conclusion: These results suggest that silane coupling agents with hydrophobic groups are not cytotoxic.

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Objectives: Chronic inflammation of periodontitis aggravates glycemic control in type-2 diabetic patients through aggravation of insulin resistance. Increased or decreased release of various inflammatory mediators, such as high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and adipokines such as adiponectin, leptin, and resistin, are thought to be responsible for the development and progression of insulin resistance. The purpose of this study was to examine the effects of periodontal treatment on glycemic control, serum inflammatory mediators and adipokines in type-2 diabetes patients with periodontitis. Methods: Forty-one type-2 diabetic patients with periodontitis received periodontal treatment with local antibiotics. Periodontal examination, including probing depth (PPD) and bleeding on probing (BOP), and blood sampling were performed at baseline, 2 and 6 months after periodontal treatment. Glycated hemoglobin (HbA1c), hs-CRP, TNF-α, IL-6, adiponectin, leptin and resistin were analyzed. Results: PPD and BOP were improved in all patients. Patients were subdivided into two groups: patients whose BOP decreased by more than 50% compared to baseline (BOP-D group), and the other patients whose BOP did not decrease by more than 50% compared to base line (BOP-ND group). Increase of adiponectin and decrease of HbA1c were observed in the BOP-D group. Although PPD and BOP were improved in the BOP-ND group, other parameters did not change significantly. A significant correlation was observed between change of BOP and change of resistin in the BOP-D group. Conclusion: The results demonstrated that successful periodontal treatment improves glycemic control with elevation of serum adiponectin in type-2 diabetic patients with periodontal disease. The results suggest that HbA1c is reduced by amelioration of insulin resistance due to elevated serum adiponectin after periodontal treatment.

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Purpose: The purpose of this study was to evaluate the efficacy of supportive periodontal therapy (SPT) for the tooth survival of periodontitis patients. Methods: Two hundred and sixty-eight periodontal patients who had been maintained for 10 years or more with SPT on an approximately 3-month recall schedule were recruited and their residual teeth and tooth loss were examined. The transition of their residual teeth to tooth loss was compared with that of the Survey of Dental Diseases (2005). Results: At the beginning of SPT, the patients (average age: 50.8) had 24.4 teeth on average. The average tooth loss for 10 years' SPT was 0.22 tooth per patient. The proportion of tooth loss in the periodontitis patients during the SPT was lower than that of the age-comparable subjects in the Survey of Dental Diseases. At the beginning of SPT, 105 patients of our study had fewer residual teeth than the age-comparable subjects in the Survey of Dental Diseases. However, after the SPT (average period: 16.7 years), our patients had more residual teeth than those in the Survey. Conclusion: These results suggest that SPT was effective for the conservation of residual teeth.

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Purpose: Inflammatory cytokines such as Interleukin (IL)-1β are secreted in pulpitis tissue during the caries process. Matrix metalloproteinase-3 (MMP-3) degrades extracellular matrix such as collagen types II , III, IV, IX, X, fibronectin, and laminin. In addition, MMP-3 can also activate other matrix metalloproteinases (MMPs) such as MMP-1, MMP-7, and MMP-9 in connective tissue. MMP-3, which is thought to be involved in wound repair, inflammation, and tumor initiation, is expressed as a result of inflammation in dental pulp. Dental pulp destruction is believed to be regulated, in part, by MMP-3 regulated degradation and regeneration of dental pulp tissue. We therefore focused on the mechanism of MMP-3 production in pulpitis tissue. C-Jun N-terminal kinase (JNK) plays a regulating role in apoptosis, neurodegeneration, cell differentiation and proliferation, inflammatory conditions, and cytokine production. In this study, we tested this hypothesis utilizing human dental pulp fibroblast like cells (HPFs) as a model system to evaluate the production mechanism of MMP-3 through stimulation with IL-1β. Methods: HPFs were incubated in serum-free α-MEM containing IL-1β (0, 10, 20, 50 or 100 ng/ml) for 24 h with or without the JNK inhibitor AS601245. Production of MMP-3 and activation of JNK by IL-1β were evaluated through the phosphorylation of JNK and MMP-3 antibodies using Western blot analysis. Results: In the present study, we demonstrated that MMP-3 was produced from HPFs in response to IL-1β in a JNK-dependent manner. IL-1β induced the production of MMP-3 without affecting the total production of MMP-2. Blocking JNK activation with AS601245 significantly inhibited IL-1β-induced production of MMP-3 without affecting the total production of MMP-2. Conclusion: These results suggest that JNK activated by IL-1β facilitates pulpitis by inducing the production of MMP-3 in HPFs.

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Purpose: Dental caries detection has been traditionally performed through visual inspection and radiographic methods. However, these diagnostic methods are subjective and have been shown to vary greatly among dentists. Due to these limitations, new quantitative technologies have been proposed to help dentists assess carious lesions. The aim of this study was to compare the performance of optical fiber or ion-sensitive field effect transistor (ISFET) micro pH sensor with a pen-type laser fluorescence device (DIAGNOdent pen) for assessing the activity of natural enamel and dentinal lesions in vitro. Methods: Thirty lesions on extracted carious teeth were divided into three groups, initial enamel caries, active dentinal caries and arrested dental caries, according to the predefined clinical criteria. The surface pH value of each caries sample was recorded by two micro pH sensors: optical fiber or ISFET. The laser fluorescence signal value was also measured by a pen-type laser fluorescence device. The results were analyzed using the Wilcoxon rank sum test within devices and Spearman's rho tests between them. Statistical significance in all analyses was set in advance at a probability level of 0.05. Results: For the optical fiber pH micro sensor, the mean pH values of the carious lesions were 5.7±0.3 (active), 6.2±0.2 (arrested) and 6.2±0.1 (initial). For the ISFET pH micro sensor, the mean pH values were 5.5±0.3 (active), 6.1±0.3 (arrested) and 6.2±0.2 (initial). For these techniques, statistically significant differences were observed in the measured pH values between active and arrested dentinal caries (p<0.05). On the other hand, for the pen-type laser fluorescence device, the mean laser fluorescence values of the lesions were 99.0±0.0 (active), 83.1±19.2 (arrested) and 33.0±20.4 (initial). For this technique, statistically significant differences in the mean signal values were observed between arrested dentinal caries and initial enamel caries (p<0.05). For all techniques, statistically significant differences in measurement values were observed between active dentinal caries and initial enamel caries (p<0.05). In addition, positive relations between the two pH measurement methods were found, and negative relations were found between the pen-type laser fluorescence device and optical fiber pH micro sensor, and between the pen-type laser fluorescence device and ISFET pH micro sensor (p<0.05). Conclusion: Based on the results of three measurements, all techniques showed usefulness for distinguishing caries activity between active dentinal caries and initial enamel caries. Furthermore, positive relations between the two pH measurement methods were found.

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Objective: The aim of this study was to evaluate the effect of a slow-start curing method on accelerating the curing of different shade resin composites at the cavity floor. Materials and Methods: Clearfil AP-X or Photo Clearfil Bright resin composite was placed in a Teflon mold. Then the resin composite was polymerized using one of two light curing techniques: 1) conventional curing method: 600mW/cm^2 for 60s, or 2) slow-start curing method: 270mW/cm^2 for 10s+interval for 5s+600mW/cm^2 for 50s. After light curing, Knoop hardness number (KHN) was measured at the top and bottom surfaces of the resin specimens. Results: A greater KHN was observed at the top surface of the resin composite than at the bottom surface with the conventional curing method for both resin composites and shade (p<0.05). The slow-start curing method showed a statistically greater KHN at the base of the resin composite than at the top surface for Photo Clearfil Bright (shade A3) (p<0.05). The same KHN at the top and base surfaces of the resin composite was recorded when using Clearfil AP-X and Photo Clearfil Bright (shade B4) (p<0.05). Conclusions: The slow-start curing method accelerated the curing of resin composite at the bottom surface. The light-curing resin composite has the property of increasing the contrast ratio during polymerization showed accelerating the curing at the cavity floor. It was suggested that this type of resin composite compensates the polymerization contraction stress.

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Purpose: We evaluated the color changes resulting from office bleaching and color variations over time using a non-contact type dental spectrophotometer. Methods: This study was performed at the Oro-facial Plastic Medical Center, Fukuoka Dental College, Medical and Dental Hospital with permission of the Institutional Review Board by the Fukuoka Dental College. After obtaining informed consent, 63 patients were examined. The teeth were bleached using a bleaching system with hydrogen peroxide (Beyond Whitening System, Beyond Dental & Health, USA) during three applications and photo-activation according to the manufacturer's instructions. After 14 days, the bleaching was done again. The tooth color was measured three times: before treatment, after office bleaching, and one month thereafter using a non-contact type dental spectrophotometer Crystaleye (CE100-DC, Olympus). The tooth color was quantified according to the CIEL*a*b* 1976 criteria (Commission Internationale de l'Eclairage, 1976). The labial surface of the tooth was divided into three areas, the "cervical", "body" and "incisal" areas. Any differences in the color of each part were statistically analyzed in comparison to the findings before treatment. The effect of office bleaching was evaluated based on the area that showed the color having the greatest statistical difference from that before treatment. The color analysis was done before treatment, after office bleaching, and one month thereafter. The obtained data were statistically analyzed by one-way ANOVA and Bonferroni's post-hoc test. Results: The color of every part of the tooth was analyzed at baseline. The body area showed a significantly different color compared to that seen in the cervical or incisal part. Therefore, the effect of office bleaching was evaluated based on the color. After office bleaching, L* was significantly higher, and a* and b* were significantly lower, in comparison to the baseline values. One month later, a* was not significantly different from that at the other time points. However, L* of most parts decreased except for the upper canines and lower lateral incisors, while b* of all parts increased in comparison to that seen after bleaching. Hence, a relapse was observed one month after office bleaching. Conclusion: Tooth color changes due to office bleaching were evaluated using a non-contact type dental spectrophotometer. Our findings suggest that the effect of office bleaching was observed objectively. However, one month thereafter, the result differed according to each tooth area and site, and the spectrophotometer findings suggested that the color change had occurred at one month after bleaching.

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Purpose: In this study, caries removal using an ultrasonic vibrating instrument with a curved shank was compared with conventional bur excavation with regard to the endpoint of dentin removal. In addition to the Micro Vickers Hardness (MVH), fluorescent caries detection devices using a laser (DIAGNOdent) or an LED (Vistacam P) were used for the comparison. Methods: Twenty extracted human teeth with dentin caries were longitudinally sectioned through the center of the caries. Micro Vickers Hardness (MVH) was measured every 200 μm from the pulp chamber to the caries region. In one group, carious dentin was removed using an ultrasonic apparatus by a dentist with 15 years of clinical experience. In the other group, carious dentin was removed using a low-speed dental cutting bur together with a caries detector (Caries Check). Subsequently, the hardness of the dentin cavity wall was confirmed, and fluorescence from the cavity wall was measured as D-values and Vistacam P values using the DIAGNOdent and Vistacam P. Results: Between the two groups, there were no significant differences in Vistacam P values (p>0.05), while the vibrating diamond tip group exhibited a significantly higher MVH and lower D-value than the control group (p<0.05). Conclusions: The use of a low-speed bur together with Caries Check is recommended in order to avoid excessive excavation of carious dentin, since the MVH and D-values suggest that the ultrasonic vibrating instrument removed a greater amount of carious dentin. Vistacam P could not detect the difference between the two caries removal methods.

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