Acid treatment of pulpal dentin of the coronal chamber to remove the smear layer and to open dentinal tubules is a promising approach to enhance the bleaching effect before walking bleaching. This in vitro study was conducted to estimate the effects of the acid treatment (10%, 20%, 40% phosphoric acid) to pulpal dentin before walking bleaching on the bond strength of resin composite restorations. To perform walking bleaching, 35% hydrogen peroxide solution and sodium perborate powder were mixed and used to fill the pulp cavity. Temporary sealing was performed using a hydraulic temporary sealing material. After preserving each specimen in water at 37℃ for 5 days, the sealing material and bleaching agent were removed, and, after washing with water, a new bleaching agent was used as filler and preserved. The same procedure was repeated three times, therefore, the bleaching agent was kept in the pulp cavity for 15 days in total. After 15 days, only a cotton ball was inserted into the pulp cavity to neutralize the bleaching agent. After preserving the specimens in water at 37℃ for 5 days, adhesive treatment of the pulp cavity was performed using Clearfil® Mega Bond, and Clearfil® AP-X was filled. As a control, after performing treatment at the above three concentrations, no walking bleaching was performed in control specimens, and adhesive treatment of the pulp cavity was carried out using the same procedure. The specimens, after completing restoration, were preserved in water at 37℃ for 24 hours. Thereafter, trimming was performed to produce dumbbell-shaped specimens of 1.0×1.0 mm in bonding area. A micro-tensile bond strength test of the produced specimens was performed using a universal testing machine, and the mean value and standard deviation were calculated (n=8). The results obtained were statistically analyzed using one-way ANOVA and Scheffe's test. Furthermore, the tensile fractured surface of dentin was observed using SEM. Regarding the influence of acid treatment and walking bleaching, no significant differences in bond strength were noted in comparison with the control group. When 10%, 20%, and 40% phosphoric acid were used for pretreatment, extensive exposure of dentin collagen fibers was detected in the fractured surface, irrespective of whether walking bleaching was performed after the pretreatment. The exposure was marked when walking bleaching was performed. Therefore, since the use of phosphoric acid as a pretreatment agent for bleaching had an adverse influence on adhesion, the use of lower-concentration phosphoric acid should be considered.

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The long-term caries inhibition effect of fluoride-containing materials (FCMs) is still a matter of debate, since the amount of fluoride released from FCM decreases with time. The purpose of this study was to evaluate the long-term caries inhibition effect of FCMs aged for 1.5 years by means of pH-cycling. Two glass ionomer cements (Fuji IX_GP Extra (EX) and Fuji IX_GP Fast Capsule (FF)), a combination of F-containing resin (Unifil-flow) and non-F adhesive (G-bond) (UG), and a combination of non-F resin (Clearfil AP-X) and F-containing adhesive (Clearfil Mega Bond FA) (AF) were used as FCMs in this study. A combination of non-F resin (Solare) and non-F adhesive (Clearfil Mega Bond) (SM) was used as a control. Each material was filled into a cavity on the buccal surface of a human premolar. Samples were stored in distilled water for 24 hours (short-time group: ST) or 1.5 years (long-time group: LT) except for SM. After storing, a 150 μm-thick single-section specimen was prepared, and then was subjected to the pH-cycling system (pH 4.5-7.0), in which six cycles were carried out per day for five weeks. A transverse micro radiography (TMR) image of each specimen was taken after 1, 3, or 5 weeks of pH-cycling and caries inhibition effect was analyzed quantitatively by integrated mineral loss (IML). The results were as follows. For the ST group, three of the FCMs (EX, FF and UG) indicated significantly lower IML compared with the control and showed caries inhibition effect by the remineralization with fluoride uptake in the adjacent cavity margin (EX>FF>UG). However, there was no significant difference in AF. For the LT group, there was no difference in IML among the FCMs and there was no difference in the caries inhibition effect which was observed in the ST group among all materials. For both the ST and LT groups, there was no caries inhibition effect by fluoride uptake in the cavity wall.

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A growing amount of evidence indicates that enamel matrix protein is effective for periodontal regeneration therapy. Tokyo Medical and Dental University Dental Hospital were given permission to administer advanced dental technology with EMDOGAIN® gel in periodontal regeneration therapy by the Ministry of Health, Labour and Welfare of Japan in October 2007. The purpose of the present study was to evaluate the clinical outcomes of the periodontal regeneration therapy using EMDOGAIN® gel (EMD) administered as an advanced dental technology. Thirty sites of 22 patients were employed in this study. Clinical examinations were performed before and one year after surgery. Probing pocket depth (PPD), clinical attachment level (CAL), and radiographic bone defect depth were measured. The mean PPD, CAL and radiographic bone defect depth before surgery were 6.1±1.4 mm, 7.1±1.8 mm and 5.6±2.7 mm, respectively. Mean PPD and CAL after one year were significantly improved to 3.1±0.8 mm and 4.8±2.1 mm. Twenty-six of the 30 sites showed gains of CAL, and the mean clinical attachment gain was 2.3±2.3 mm. The mean radiographic bone defect depth decreased to 3.1±1.8 mm. The results of the present study were consistent with those of previous reports on clinical and radiographic periodontal tissue regeneration. EMD has several technical advantages compared with GTR, which is covered by dental health insurance, and its procedure is more simple. Additionally, it can be used for multiple bone defects at the same time. In conclusion, promoting the advanced dental technology using EMDOGAIN® gel may provide adequate clinical outcomes for periodontally-involved patients while reducing the cost of treatment.

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Pluripotent mesenchymal stem cells are essential for regeneration by tissue engineering. These stem cells, which are derived from periodontal ligament, bone marrow and dental pulp, are used in the dental field. We evaluated the properties of adult dental pulp cells collected from teeth extracted for orthodontic reasons and cultured the cells with b-FGF (basic-fibroblast growth factor) to promote the growth of mesenchymal stem cells. ALP activity and gene expression of osteopontin (OPN), osteocalcin (OC), bone sialoprotein (BSP) and dentin sialophosphoprotein (DSPP) were determined. The results showed that ALP activity increased and gene expression of the bone molecular markers, OPN, OC and BSP, and DSPP, a molecular marker of dentin, increased in the presence of b-FGE When surface antigens of dental pulp stem cells cultured in the presence of b-FGF were examined, the hematopoietic stem cell markers CD34 and CD45 were negative, and the mesenchymal stem cell markers CD44 and CD90 were positive. The cultured dental pulp stem cells were then transplanted into artificially created periodontal bone defects in nude rats using collagen gel as a carrier. Connective tissue attachment and bone regeneration were not found in the control defects where only collagen gel was transplanted, but connective tissue attachment was observed in the experimental defects in which collagen gel and cells were transplanted. In the present study, no regeneration of alveolar bone was observed, but periodontal tissue regeneration using dental pulp stem cells appeared to be possible.

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When repairing restored cast-metal teeth using an adhesive metal primer, it is difficult to apply the primer to a metal surface alone. For this reason, the metal surfaces will frequently become stained by adhesive dentin and/or ceramic primers. The purpose of the present study has been to investigate 1) the influence of a combined application of an adhesive metal primer and a silane coupling agent on the bond strength between a resin composite and a gold-silver-palladium alloy, and 2) the influence that a metal surface grinding condition will have on this bond strength. Gold-silver-palladium alloy castings were fabricated in a conventional manner. The surfaces of the castings were ground using either a 600-grit SiC paper or a carborundum point, or were blasted with 50-μm alumina particles. The metal surfaces were primed using one of three adhesive metal primers (Alloy Primer® ; Kuraray Medical, Metal Primer II® ; GC and V-Primer® ; Sun Medical). A silane coupling agent (Clearfil Porcelain Bond Activator® ; Kuraray Medical) was used and applied with Clearfil Mega Bond® (Kuraray Medical), Clearfil ST Opaquer®(Kuraray Medical) and Clearfil AP-X® (Kuraray Medical) were then bonded to the treated surfaces. The bonded specimens were subjected to tensile bond strength tests after being stored in water for 48 h at 37℃. The results of this study indicated that the adhesive metal primers increased the bond strength between the resin composite and the alloy castings, whereas the silane coupling agent had no influence on the bond strength. The results also indicated that the bond strength also depended on the grinding condition of the casting surfaces, with the highest bond strength found for an alumina blasted surface. No difference in bond strength was found among the three adhesive metal primers.

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We surveyed the current number of teeth and survival rate by tooth type using panoramic images of elderly patients. Eight hundred and twenty-one patients (378 males and 443 females, ≥60 years) who had visited the hospital of Matsumoto Dental University from August 2007 to December 2010, who had undergone panoramic imaging for diagnosis of dental treatment, and who consented to participate were enrolled in this study. The proportion who maintained ≥20 teeth was higher compared with the results of the Japanese national survey on dental diseases in any age group: it was 83.2% in those aged 60-64 years, 72.9% in 65-69 years, 56.3% in 70-74 years, 39.6% in 75-79 years, 40.4% in 80-84 years and 25.9% in ≥85 years. The current survival rate of the teeth was higher among anterior teeth and canines, with the highest rate of 91.1% for mandibular canines and 85.4% for mandibular lateral incisors. The lowest survival rate was 52.4% for mandibular second molars and 53.0% for mandibular first molars among molar teeth. The current survival rate of teeth tended to be higher compared with the results of the Japanese national survey, because of improvements in dental health activities and dental health awareness in elderly patients who had visited the hospital of Matsumoto Dental University.

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The present study investigated the effect of a prototype fluoro-alumino-calcium-silicate glass-containing tooth-coating material (Nanoseal, Nihon Shika Yakuhin) on the ultrastructure, acid resistance, and elemental distribution of enamel and dentin surfaces in vitro. Labial enamel and dentin surfaces of extracted human incisors were used as test surfaces. Each specimen was twice coated with Nanoseal for 10 seconds, followed by being stored in phosphate buffered saline (pH 7.2) at 37℃ for 24 hours. For surface morphological observation, the specimens were coated, by using nail enamel, with Nanoseal covering half of the test surface. The specimens were then washed in acetone to remove the nail enamel, and demineralized in an acetic acid buffer (pH 4.5) for 24 hours. The surface ultrastructure was then analyzed by using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with an image observation function (SEM-EPMA). For cross-sectional morphological observation and elemental distribution analysis, specimens were coated with Nanoseal, cross-sectioned, and analyzed with the SEM-EPMA. The surface analysis demonstrated that Nanoseal-coated surfaces show a deposition of nanoparticles, whereas uncoated surfaces show typical features of demineralization. The cross-sectional analysis revealed the formation of a nanoparticle-deposited layer, 1-2μm in thickness, on the enamel and dentin surfaces; and occlusion of dentinal tubules with nanoparticles in the dentin specimens. Moreover, incorporation of F and Si was detected in the superficial layer of the enamel and dentin specimens. In conclusion, the Nanoseal coating on the enamel and dentin surfaces resulted in a deposition of nanoparticles, the incorporation of F and Si into the coated surfaces and a resistance to acetic acid demineralization, which suggests that Nanoseal possesses anti-cariogenic and dentin desensitizing effects.

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There are many cases diagnosed in routine dental practice as persistent apical periodontitis with continuous and oppressive apical pain, occlusal pain, and pain on percussion. It is particularly difficult to diagnose persistent cases that are caused by apical fenestration with two-dimensional (2D) X-rays. Such cases are often treated in general dental offices as unexplained persistent apical periodontal disorders. This article reports cases referred to our Department for treatment that are caused by apical fenestration among those cases where general practitioners have made a diagnosis of either persistent apical periodontitis with continuous and oppressive apical pain, or strange sensations on percussion mainly in the anterior maxilla. We diagnosed and treated ten cases in which general practitioners had made a diagnosis of persistent apical periodontitis and had been referred to the Department of General Dentistry, Tokyo Dental College Suidobashi Hospital. Of the ten cases, seven cases were positively diagnosed preoperatively with CT images and three cases were diagnosed by palpation of the periapical gum in each affected tooth for an apicoectomy in a normal manner. The ten cases were then followed-up. In the majority of cases, lateral condensation was performed under clear vision using gutta-percha points and Finapec APC® immediately before the apicoectomy, rather than reverse canal filling. The maximum term of postoperative follow-up of four years showed a disappearance of discomfort, such as that of oppressive apical pain, for all ten cases. These results suggest that an apicoectomy as a therapeutic approach to persistent apical periodontitis due to apical fenestration is considered to be an effective option.

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Provisional restorations are used to prevent damage from occurring during the interim period between tooth preparation and fitting a definitive restoration, and to ensure occlusion and aesthetics. Maintaining long term stability of provisional restorations in an oral environment is required for complex treatment. Recently, bis-acryl base resins containing inorganic fillers have been made available to develop long term stability in an oral environment. Although there are several pieces of research that refer to their mechanical properties, little is known about their long term stability and erosive wear behavior. The purpose of this study was to determine the long term stability and erosive wear behavior of provisional resins. During the course of this research, we compared the following properties; flexural strength after thermal cycling, water sorption, density, tooth-brushing abrasion, and the sliding-impact wear of bis-acryl provisional resins compared with PMMA resins. The results were as follows: 1. Bis-acryl provisional resins reveal a significantly higher flexural strength and elastic modulus in comparison to PMMA provisional resins. 2. Bis-acryl provisional resins reveal a significantly lower water sorption than that of PMMA provisional resins. On the other hand, bis-acryl provisional resins demonstrate a higher density in comparison to PMMA provisional resins. 3. From results obtained in a tooth-brushing abrasion test, bis-acryl provisional resins demonstrate a significantly lower abrasion rate in comparison to PMMA provisional resins. 4. From results obtained in a sliding-impact wear test, bis-acryl provisional resins demonstrate a significantly lower abrasion rate and depth of wear in comparison to PMMA provisional resins.

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The instruments, materials and medicines used in dental treatment are reported to differ among universities that educate dentists. This means that there may be differences in the operative procedures and in the instruments, materials and medicines used in actual dental practice. These differences can affect the training of dental hygienists, who will be placed in internships at several medical facilities outside of their schools. We conducted a survey among students who had completed internships to determine the instruments, materials, medicines and operative procedures used at medical facilities outside of the schools where the students received their clinical training. In particular, we compared the survey results to conservative dentistry procedures followed at university hospitals and general dental clinics. A questionnaire was conducted for 94 students in a dental hygienist training program. The questions included items related to materials, instruments and operative procedures used for root canal treatment at the various facilities where they served their internships. The results of the survey showed that there were slight differences between university hospitals and general dental clinics with regard to the instruments used for root canal preparation. Also, the root canal disinfectants used at university hospitals and general dental clinics varied considerably. There were also small differences between university hospitals and general dental clinics with regard to sealing and root canal filling methods. The present study showed that root canal treatment procedures and materials used at university hospitals slightly differed from those used at general dental clinics. Students in dental hygienist training institutions must learn to adapt to the various types of instruments, materials, and operative procedures used at clinical training facilities.

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The content of fillers in bonding agents influences their mechanical characteristics and hardening properties. Therefore, we experimentally produced bonding agents, which have the same basic compositions of adhesive and base monomers, and contain surface reaction-type pre-reacted glass-ionomer (S-PRG) fillers, which are characterized by the sustained release of fluoride ions, the release of metal ions such as Al³⁺ and Sr²⁺, and metalloid ions such as SiO₃^2- and BO₃^3-. We changed the content of the S-PRG fillers between 0-40 wt%, measured the tensile bond strength for teeth, and performed various mechanical strength (direct tensile, bending and thin film interfacial strength tests) and hardening property tests (ESR measurement of free radicals and FT-IR measurement of the rate of polymerization). As a result of the tests, the tensile bond strength of bonding agents as basic compositions of UDMA/TEGDMA/HEMA for enamel and dentin was highest when the content of the S-PRG fillers was 40 wt%. With regard to the various mechanical tests, a direct tensile strength test, in which tensile stress was applied to the specimens, showed a tendency similar to that of a tensile bond strength test. As a result of a 3-point bending strength test, in which both compressive and tensile stresses were applied, the strength was highest when the content of the S-PRG fillers was 0 wt%. Furthermore, no significant differences were noted in a thin film interfacial strength test, in which a shearing stress was applied. As the results of an analysis of UDMA/TEGDMA/HEMA polymerization radicals, and FT-IR measurement of the rate of polymerization, the rate of polymerization was low when the content of the S-PRG fillers was 20 wt%, and the rate increased at 30 and 40 wt%, causing no inhibition of polymerization. We believe that the content of fillers in bonding agents contributed to an increasing of the mechanical strength, but also promoted a brittle mechanical property. Changing the content of S-PRG fillers would not extensively affect the inhibition of polymerization in bonding agents. We consider that it is necessary to evaluate not only the content of the fillers, but also the influence that differences in their mechanical properties has on the connection of the fillers and matrix resin.

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The purpose of this study was to evaluate the influence of cavity wall on resin composite bond strength to dentin using two adhesive systems. The occlusal enamel of human molars was ground to expose a flat dentin surface and finished with carbide paper. Box-form occlusal cavities measuring 3 mm wide, 5 mm long and 2 mm deep (C-factor=3.1) were prepared on the flat dentin surfaces of human molars. Each specimen was restored with one of two self-etching adhesive systems: Clearfil Mega Bond (Kuraray Medical) or Clearfil Tri-S Bond (Kuraray Medical), followed by bulk filling using Z100 resin composite (3M ESPE). After light-curing at 600 mW/cm² for 40 s, teeth were stored in the dark for 24 hours in water maintained at 37℃. A specimen was cut perpendicular to the cavity floor and cavity wall to obtain beams having cross-sectional areas of approximately 0.9 mm², and the micro-tensile bond strength (μTBS, MPa) was determined. Data (n=10) were analyzed using Tukey's test. Clearfil Mega Bond showed higher bond strength to both the cavity floor and cavity wall compared with Clearfil Tri-S Bond (p<0.05). There was no significant difference in bonding between cavity floor and cavity wall when using Clearfil Mega Bond (p>0.05). Resin composite bond strength to the cavity floor was lower than that to the cavity wall using Clearfil Tri-S Bond (p<0.05). The bond strength of resin composite to the dentin varied at different sites of the cavity and was influenced by the adhesive system used.

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The purpose of this study was to evaluate the effect of dentinal tubule orientation on resin composite bond strength to floor and wall using various adhesive systems. Box-form occlusal cavities measuring 3 mm wide, 5 mm long, and 2 mm deep were prepared on flat dentin surfaces of human molars. The walls of the cavities were then removed to make flat dentin floors and walls for bonding. Each specimen was restored with one of two adhesives: Clearfil Mega Bond (Kuraray Medical) or Single Bond (3M ESPE), followed by build-up using Z100 resin composite (3M ESPE). After light-curing at 600 mW/cm² for 40 s, teeth were stored in the dark for 24 hours in water maintained at 37℃. A specimen was cut parallel to the floor or wall to obtain approximately 0.9 mm² beams. The microtensile bond strength (μTBS, MPa) to the flat dentin floor or wall specimen was determined. Data (n=11) were analyzed using Bonferroni's test. The bond strength of Clearfil Mega Bond to the dentin wall group showed the highest bond strength among all groups. Clearfil Mega Bond and Single Bond showed significantly higher μTBS to dentin wall compared with that of the dentin floor group (p<0.05). Bonding to dentin floor and wall was affected by dentin location and dentin tubule orientation.

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