Self-adhesive resin cement has been developed as a luting agent without pretreatment of the adherent surface. Though, these resin cements are used for indirect ceramics restoratives, the adhesive stability to the adherent surface is not clear. The purpose of this study was to examine the adhesive performance of self-adhesive cement to ceramics and dental casting alloy by determining the bond strength through SEM observation. The effects of ceramics primers on the adhesive properties were also examined. From the results of this study, bond strength of self-adhesive resin cements were higher than those of resin-modified glass-ionomer cements. No significant difference were found for shear bond strength. When a ceramics primer was not used for pretreatment, the predominant failure was adhesive failure. Though bond strength data were not influenced by the use of ceramics primers, the fracture mode after the bond strength test became more complex.

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We previously showed that in clinical practice minimal intervention (MI) is used less frequently for non-vital teeth than for vital teeth. We also showed that MI recognition did not result in an increase in the clinical use of MI restorations (restorations based on MI) for non-vital teeth, but did so for vital ones. However, there were also dentists who did not necessarily select MI restorations, even though they knew of MI and intended to use MI restorations. This study aimed to clarify factors limiting the increased clinical use of MI restorations. We surveyed 133 dentists working at Kyushu University Dental Hospital about MI. The questionnaire included colour illustrations of two carious cavities: a small distal carious cavity in a mandibular second premolar (Case 1, an example of a vital tooth) and a large mesio-occlusal-distal cavity in a mandibular first molar (Case 2, an example of a non-vital tooth after root canal filling). The questionnaire was designed to obtain data regarding the dentists' attitudes toward and use of MI: MI recognition, intention to use MI restorations, selection of restorations for Cases 1 and 2, and reasons for the selection. We performed discriminant analysis to determine which reasons for selection discriminated between MI restorations and conventional restorations (restorations based on GV Black's concept for vital teeth, and a full coverage crown for non-vital teeth), which revealed the characteristics of respondents who selected conventional restorations. Compared with respondents having a strong preference toward MI restorations, respondents who selected conventional restorations more often indicated prevention of recurrent caries, acquiring retention force for vital teeth, prevention of tooth fracture and acquiring retention force for non-vital teeth as reasons for their selection. These results indicated that the factors limiting the clinical use of MI included concerns about the adhesive properties of adhesive materials and their influence on the recurrence of caries in vital teeth or tooth fractures in non-vital ones. The discriminant analysis also revealed that the reason, "preservation of the remaining tooth structure," alone discriminated MI and conventional restorations for non-vital teeth, with very few respondents who selected conventional restorations indicating this reason, while most respondents who selected MI restorations did. Therefore, it will be necessary to accumulate evidence about the applicability and usefulness of MI restorations with adhesive materials, along with data about the importance of preserving the remaining tooth structure for tooth longevity.

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The purpose of this study was to evaluate the wear rates of light-cured resin composites placed against stainless rods. Nine different light-cured resin composites were used. Resin paste was placed into a Teflon mold and light-cured for 60 seconds through polyethylene strips and stored in 37℃ distilled water. After 48 hours, the surfaces of the specimens were wet ground with #2,000 SiC paper and served as specimens for the impacting-sliding wear test. These specimens were loaded at 5kgf and individually subjected to 50,000 cycles of localized wear. After completion of the wear cycle, the maximum-depth wear loss of light-cured resin composites was measured using a scanning laser microscopy, and the surface texture was observed with scanning electron microscopy (SEM). The results were as follows: 1. Mean maximum wear rates of light-cured resin composites were 83.9-111.4μm, and differences were found in the materials tested. Mean maximum wear rates of posterior composites were 79.2 and 109.0μm, showing a significant difference between the materials. 2. From SEM observation of light-cured resin composite surfaces after mechanical stress, the surfaces were different among the materials used, depending on their filler particle size and form.

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Mastic is a resinous exudate obtained from the stem and main leaves of Pistacia lentiscus. The aim of the present study was to assess the clinical and microbiological effect of a sonic toothbrush (SB) and a mastic-essential-oil compound dentifrice (MD) on chronic periodontitis, in a randomized control trial. Twenty-two volunteers with chronic periodontitis were assigned in random to the two groups; the experimental group (SB+MD): 11 patients (6 males, 5 females, mean age 63.2 years) and the placebo group (SB+non-MD): 11 patients (4 males, 7 females, mean age 55.5 years). Three sites per each were subjected. At the baseline and at 2 and 4 weeks, clinical measurements were performed using clinical parameters. In addition, subgingival plaque was collected at the baseline and at 4 weeks. A quantitative analysis of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Tannerella forsythensis, Prevotella intermedia was carried out using real-time polymerase chain reaction (PCR) procedures. There was no significant difference between the two groups with regard to the clinical conditions at the base line. A significant decrease of inflammation was noted after using a sonic toothbrush and dentifrice for 2 and 4 weeks in both the mastic group and the placebo. As for swelling, bleeding, and plaque accumulation, the mastic group showed a significant improvement compared to the control (p<0.05). A significant suppression of P. gingivalis and red complex in the ratio against total bacteria cell counts after 4 weeks of treatment were observed only in the mastic group (p<0.01, p<0.05, respectively). This study suggests that a sonic toothbrush and a mastic-essential-oil compound dentifrice may be useful for chronic periodontitis.

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Aesthetic tooth-coating systems have been developed to provide natural tooth color by placing a thin temporary resin layer, which is easily applied, to discolored enamel or restorations without any tooth preparation. The purpose of this study was to determine the color stability of two different tooth-coating systems using different finishing procedures according to ISO7491. Two tooth-coating systems, BeautiCoat (Shofu) and White Coat (Kuraray Medical) were evaluated, and Clearfil AP-X resin composite (Kuraray Medical) was used as the control. The White bases of BeautiCoat polymer or the Base Coat polymer of White Coat were applied to a 10mm disk of polymerized Clearfil AP-X for each disk (n=3). 1) After placing the White base on the disk and light curing it, the surface was covered with Gross Maker oxygen-inhibitor, light cured and rinsed with chip syringe water, and after 3 days the surface was polished with Gross Refine on a buff disk (standard finishing; BC). 2) After placing the White base on the disk and light curing it, the unpolymerized surface was removed with sterile gauze, and immediately polished with Gross Refine on a buff disk (GR). 3) After the White base was light-cured, the surface was covered with Gross Maker and light-cured (GM). 4) For the finishing method of the White Coat system following light-curing of its Base Coat, the unpolymerized surface layer was removed with sterile gauze, and Top Coat was applied to the unfilled surface and light-cured (WC). 5) Clearfil AP-X disks were evaluated as controls. Each specimen was evaluated according to ISO7491 for postulation of clinical long-term composite resin evaluation. Half of each specimen was covered with aluminum foil to block all light exposure and then placed under Xenon light exposure (Suntest CPS+ Type X: 45). The specimen was immersed in water at 37℃ and exposed to a 150,000 Lux Xenon light for 24hrs. The CIE L*a*b* of each specimen was measured by a Spectro Color Meter (SE-2000) with three different background values of gray, white or black. Color differences ΔE*ab and translucency parameters of each disk were calculated as well as for color stability evaluation. The results are as follows: 1. The color difference ΔE*ab between the exposed side and the protected side on a gray background was 4.29 for GM, followed by 3.40 for WC, 3.20 for GR and 2.46 for BC. 2. The color change increased toward yellow for all groups. 3. Significant differences of translucency parameter value were observed in the immediate finishing group.

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We have recently detected tooth pulp-driven neurons (TPDNs) in the rat's thalamic mediodorsal nucleus (MD), the largest nucleus in the medial thalamus, and analyzed the alteration of their responsiveness induced by chemical conditioning stimulation with a small fiber excitant and inflammatory irritant, allyl-isothiocyanate (mustard oil: MO), applied to the rat's molar tooth pulp. The aim of the present study was to elucidate the involvement of the N-methyl-D-aspartate receptor (NMDAR) mediated mechanisms in responsiveness changes of MD TPDNs following MO application to the rat's molar tooth pulp through electrophysiological and molecularbiological studies. Microinjection of MK-801 (200nmol/0.5μl), a noncompetitive NMDAR antagonist, into the recording site reduced neuronal responses of the TPDNs in the MD (p<0.05, Mann-Whitney U-test). RT PCR analysis for the NMDARs mRNA revealed that the two subtypes of the NMDARs (NMDAR2A and NMDAR2D) were expressed and up-regulated by the MD tooth pulp application, both of which were reduced by the microinjection of MK-801 into the surrounding regions of the TPDNs recording site. The results of the present study demonstrated that the TPDN responses in the MD nucleus were modulated by activating the NMDA receptor following tooth pulp conditioning stimulation with MO.

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The purpose of this study is to examine the influence of laser irradiation of dental hard tissues and to confirm the optimum irradiation conditions (output energy, repetition rate and ratio of water/air) with an Er, Cr: YSGG laser. The Er, Cr: YSGG laser apparatus used in this study was a Waterlase™ MD® (Biolase Technology, USA). Extracted human molars without a carious region were collected from the Department of Oral Surgery, Osaka Dental University Hospital and stored frozen before the experiment. The enamel and dentin surface of the thawed teeth was ground to #2,000. Initially, we fixed the ratio of water at 30%, and air at 60%. The Er, Cr: YSGG laser was irradiated for one second at an irradiation distance of 1mm to the ground enamel and dentin surfaces at repetition rates of 0.25, 1.00, 3.00 and 5.00W at output energies of 10, 20 and 50Hz. The irradiated mass of the removed teeth (caliber, depth and removal volume) and the tooth quality were observed. Next, based on previous results, the output energy was increased to 5.00W in enamel and 3.00W in dentin with a repetition rates at 20Hz in both the enamel and dentin. The Er, Cr: YSGG laser was irradiated for one second, at an irradiation distance of 1mm to the ground enamel and dentin surfaces at various ratios of water and air. The irradiated mass of the removed teeth (caliber, depth and removal volume) and the tooth quality were observed. The results were as follows: 1. In both the enamel and dentin, the amount of removal was increased by raising the output energy and lowering the repetition rate. 2. In both the enamel and dentin, cracks indicating the influence of heat were observed. 3. Effective removal was possible at an output energy of 5.00W with a repetition rate of 20Hz in enamel and 3.00W in dentin, and with a repetition rate of 10Hz in dentin. 4. Effective removal was possible with 95% water for enamel and 75% for dentin, and 100% air for both enamel and dentin.

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The purpose of this study was to evaluate the factors influencing the sealing ability of an adhesive root canal filling material. Thirty-four single-rooted human mandibular premolars were used. The crowns were removed, and the root lengths were standardized to 12mm. Two teeth were used as negative controls. The remaining 32 teeth were randomly divided into 4 groups of 8 teeth each. Then, they were prepared and filled with one of the following methods: Group A: The root canal was prepared to a .10 taper and filled with .02 gutta-percha point+Canals® N using the lateral condensation method. Group B: The root canal was prepared to a .10 taper and filled with .02 gutta-percha point+MetaSEAL™ using the single cone technique. Group C: The root canal was prepared to a .06 taper and filled with .02 gutta-percha point+MetaSEAL™ using the single cone technique. Group D: The root canal was prepared to a .06 taper and filled with .06 gutta-percha point+MetaSEAL™ using the matched taper single cone technique. After the root canal filling procedure, a polypropylene tube containing 0.06% methylene blue dye solution was attached to the coronal portion of each root. The apical portion, 2mm in length, was immersed in a glass bottle containing distilled water. The amount of dye penetrating through the root into the water was measured with a spectrophotometer at 1, 4, 8, 15 and 30 days after the immersion. Data obtained were statistically analyzed using the ANOVA and the Tukey-Kramer at 5% significance levels. Finally, horizontal sections were made at 1mm steps to 6mm from the apex. The images of the horizontal sections were taken by a digital microscope at 100×magnification. There were significant differences among the groups and experimental time intervals (p<0.05). Statistical analysis revealed that the amount of leaked dye in group B on the 30th day was significantly larger than that in the other three groups (p<0.05). As for the negative control group, no methylene blue dye was detected throughout the experimental period. In the images of the horizontal sections of groups A, B and D, dye penetration was seen at all levels, while no stains were found in group C. It was suggested that when using a resin-based root canal sealer, the thickness of the sealer layer might influence its root canal sealing ability. The conventional root canal sealer used in this experiment showed an effective sealing ability as good as the resin-based root canal sealer, when the sealer thickness is thin enough. Although the matched taper single cone technique was effective to minimize the sealer thickness, it was not effective to reduce the amount of leakage.

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This article describes the endodontic treatments of two cases of chronic apical periodontitis of mandibular second incisors with two separate root canals, using an intracanal endoscope, which enabled a more accurate diagnosis to be made. In addition, the combined use of an Er:YAG laser under endoscopic observation allowed minimally invasive therapy to be conducted. The intracanal endoscope might be a useful device for resolving endodontic problems, in combination with cone beam computed tomography and an operating microscope.

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The aim of this study was to evaluate the function of Chloramine-T as a root canal irrigant. Varying concentrations of Chloramine-T and hydrogen peroxide (H₂O₂) were examined for tissue dissolution activity using rat rectus muscles, pH changes, free radical generation by means of electron spin resonance (ESR) spin trapping, tissue damaging activity using rat rectus muscles, and cytotoxicity in cultured human periodontal ligament cells. When 5.0% and 10.0% Chloramine-T or 3.0% H₂O₂ were applied to rat rectus muscles for 1 hour, the weight of rat rectus muscles decreased. However, the weight of rat rectus muscles was not changed when 0.5% and 1.0% Chloramine-T or 1.0% H₂O₂ were applied. The pH values of 0, 0.5, 1.0, 5.0 and 10.0% Chloramine-T were 6.22, 6.85, 7.83, 9.33 and 9.97, respectively. When these concentrations of Chloramine-T were applied to rat rectus muscles, each pH changed to 6.30, 7.07, 7.45, 7.52 and 7.51. Also, the pH values of 0, 1.0 and 3.0% H₂O₂ were 6.22, 5.20 and 4.65, respectively. When H₂O₂ was applied to rat rectus muscles, each pH changed to 6.54, 6.84 and 6.72. ESR spin trapping revealed that DMPO-X was detected from Chloramine-T in the order of 0.5%>1.0%>5.0%>10.0%>0%, and hydroxyl radical (OH・) was detected from H₂O₂ in order of 3.0%>1.0%>0%. When Chloramine-T was applied to rat rectus muscles, the DMPO-X signals were diminished. However, the ESR signals showed no changes when H₂O₂ was applied to the rat rectus muscles. Histological observation of Chloramine-T and H₂O₂ exposed rat rectus muscles demonstrated atrophy of muscle fibers, dissolution of connective tissues and disappearance of striations in a does-dependent manner. H₂O₂ caused stronger damages as compared with Chloramine-T. In the cytotoxicity experiments, the survival rate of human periodontal ligament cells decreased in a dose-dependent manner with Chloramine-T and H₂O₂. The survival rate was 100, 38.5, 33.6, 33.6 and 23.0%, when 0, 0.5, 1.0, 5.0 and 10.0%, respectively, of Chloramine-T was applied. The survival rate with 0, 1.0 and 3.0% H₂O₂ was 100, 14.9 and 14.7%, respectively. These results suggested that Chloramine-T is a milder root canal irrigant than H₂O₂.

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It has been suggested that reducing the surface free energy of the tooth surface may prevent plaque accumulation and reduce the incidence of caries and periodontal disease. We synthesized a novel aqueous hybrid surfactant that can be added to dentifrice, namely sodium phenyl 1-[(4-perfluorohexyl)phenyl]-1-hexylphosphate (F6H5OP), which is a molecule containing a long fluorocarbon chain, a hydrocarbon chain, and a phosphate ester. In this study, we investigated the reduction in surface free energy on a hydroxyapatite (HAP) pellet and the inhibition of the calcium binding protein, phosvitin, on HAP powder modified with F6H5OP The amount of F6H5OP adsorbed to the HAP powder was determined by high-performance liquid chromatography. The F6H5OP water solution was applied to HAP pellets with a microbrush. The specimens were stored in water for 3 and 12 hours at 37℃. The surface free energies of the modified specimens were calculated by measuring the surface contact angles of distilled water and diiodomethan. The amount of phosvitin adsorbed to the HAP powder was determined by gel permeation chromatography. The resistance to rinsing with deionized water and the inhibitory effect of phosvitin adsorption to HAP powder were also measured. More than 70% of F6H5OP in deionized water was adsorbed to the HAP powder within 5 minutes. The contact angles of the HAP pellets modified with F6H5OP were significantly higher than that of the non-treated control, and the surface free energies were significantly lower than that of the control after the 12-hour water immersion. The inhibition ratio of phosvitin adsorption to modified HAP powder following rinsing twice with deionized water was about 40% after immersion in water for 12 hours. These results suggest that the novel phosphate-type hybrid surfactant F6H5OP has a significant modification effect on the surface of hydroxyapatite.

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The purpose of this study was to clarify the anti-plaque mechanism of a composite resin containing S-PRG filler and to examine both in (in vitro and in vivo) the protein adsorption modality on the surface of the composite resin. The tested materials were; composite resin containing 40wt% S-PRG filler, the base resin and bovine enamel. In addition, the four components of a resin composite product that contain S-PRG filler (Beautifil) were used; S-PRG filler, MF (multi functional) glass filler, ultrafine particle alumina filler and powdered base resin. Blocks of S-PRG filler resin and base resin were prepared and attached to the buccal surface of the upper first molar in the mouth for 2, 8 and 24 hours, respectively. After that, the blocks were observed under a scanning electron microscope (SEM), analyzed with an energy dispersive X-ray micro analyzer (EDX) and an electron probe micro analyzer (EPMA). Subsequently, examination of the total protein adsorption rate was performed in vitro by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. Each supply material was soaked in human saliva for the SDS-PAGE analysis. The protein band was detected by silver staining after electrophoresis, and the molecular weight of the protein was calculated from a relative mobility. Furthermore, protein adsorption was analyzed in vivo by the immunity SEM method, and five kinds of proteins were selected (Mucin1, Lactoferrin, IgA, Cystatin-C, Lysozyme) as the first antibody. As a result, the SEM observation showed that both surfaces (S-PRG filler resin and base resin) were similar after the blocks were removed from the mouth; however, the EDX analysis showed different components (F, Al, Si, Sr) in their structures. Moreover, the formation of mature dental plaque was witnessed in the base resin, even though the adhesion of plaque on the surface of S-PRG filler resin tended to be localized. Additionally, greater concentration of nitrogen was detected by EPMA in S-PRG filler resin and base resin after the blocks were removed from the mouth. The electrophoresis analysis exhibited that S-PRG filler has the property to adsorb 14kDa of saliva proteins. The main proteins detected on the surface of S-PRG filler resin by the immunity SEM method were Cystatin-C and Lysozyme. For S-PRG filler resin and S-PRG filler, the antibodies molecular weights were similar to the molecular weights obtained in the electrophoresis analysis that was previously carried out in vitro. The structure of the pellicle formed on the surface of the resin composites and the adsorption of the saliva proteins were examined in vitro and confirmed in vivo. Numerous anti-bacterial proteins were detected on the surface of S-PRG filler resin; therefore, the proteins composition could control in some way the formation of dental plaque.

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Interleukin (IL)-6 is a major mediator in a host response against tissue injury and bacterial infection. It is highly released by macrophage, fibroblast and endothelial cells in the inflammatory regions. Recently, it has been studied that the fibroblast growth factor (FGF)-2 is used in clinical regeneration of dentin-pulp complex lost due to dental caries or trauma. The purpose of this study was to investigate the effect of IL-6 on the expression of FGF-2 in human dental pulp cells. Dental pulp cells were cultured in the medium with IL-6 at a concentration of 0, 0.1, 1, 10ng/ml for 3 weeks. The expression of FGF-2 in the cells was examined by the method of a real-time PCR. Statistical analysis was done by one-way ANOVA. The localization of FGF-2 in dental pulp cells was also examined by immunohistochemical staining. As a result, a real-time PCR analysis revealed that IL-6 at a concentration of 1 and 10ng/ml inhibited the expression of FGF-2 mRNA in the cultured cells and immunohistochemical staining demonstrated that IL-6 clearly decreased the immunoreaction against FGF-2 in the dental pulp cells. These results indicated that IL-6 inhibited the FGF-2 expression in dental pulp cells.

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Periodontal diseases such as periodontitis represent a serious clinical challenge. The final goal in the treatment of periodontal diseases is the regeneration of periodontal tissue. Recent developments in tissue-engineering technology has led to the ex vivo cultivation of periodontal ligament (PDL) structures. Some studies have demonstrated that PDL-derived cells could regenerate periodontal tissues, and indicated that PDL cells and scaffolds have key roles in periodontal regeneration. However, there has been no report on the use of amniotic membrane (AM) as a scaffold for PDL-derived cell sheets. AM has high biocompatibility as well as anti-scarring and anti-infection properties. In the current study, we immunohistochemically evaluated PDL-derived cells cultured on AM. All experimental procedures introduced here were approved by the Kyoto Prefectural University of Medicine Ethics Committee. AM was obtained from women undergoing caesarean section. PDL tissue was obtained from a healthy human maxillary third molar that had erupted. The PDL tissue was minced and then cultured in a culture medium as explants. After 3rd to 4th passages, the PDL-derived cells were first cultured on an AM carrier and then evaluated immunohistochemically for distribution of Ki-67, vimentin, desmoplakin, and zonula occludens protein-1 (ZO-1), using an indirect fluorescent antibody method. PDL-derived cells showed a monolayered structure after 2 weeks in culture on AM. Immunohistochemistry revealed that PDL-derived cells cultured on AM expressed Ki-67, vimentin, desmoplakin, and ZO-1. These findings indicated that the cultivation of PDL-derived cells using AM enabled PDL-like differentiation. In addition, those cells showed desmosomes and tight junction-mediated cell-to-cell adhesion. We concluded that AM may represent a suitable scaffold for culturing PDL-derived cells, and that PDL-derived cells cultured on AM show sheet formation.

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