Purpose: Fibrillin-1 is the main structural component of extracellular microfibrils, and is known to contribute to the release of transforming growth factor-β (TGF-β) upon its degradation. We have also demonstrated that fibrillin-1 immunoreactivity disappears during the wound healing process of direct-capped human dental pulp. In this study, we extended our investigation to fibronectin and decorin (known as extracellular regulators of TGF-β) and tenascin-C (known to contribute to wound healing and tissue fibrosis), and examined whether these molecules show distributional changes similar to those observed for fibrillin-1 during the healing process of direct-capped human pulp. Human pulp slice cultures were also examined for the involvement of matrix metalloproteinases (MMPs) in the disappearance of fibrillin-1 immunoreactivity. Methods: Clinically healthy human teeth scheduled for orthodontic extraction were directly pulp-capped with mineral trioxide aggregate (MTA). After 2 or 6 weeks, the teeth were extracted and processed for immunohistochemical staining of fibrillin-1, fibronectin, decorin and tenascin-C. Cultured healthy pulp tissues were analyzed for (1) fibrillin-1 mRNA expression with quantitative RT-PCR, and (2) distributional changes of fibrillin-1 immunoreactivities after addition of an MMP inhibitor (NNGH). Results: At 2 and 6 weeks after direct pulp capping, immunoreactivity for fibrillin-1 disappeared under the exposure site of dental pulp. Immunoreactivities for fibronectin, decorin and tenascin-C were constantly detected beneath the exposed area of the pulp and no apparent distributional changes were recognized. Cultured pulp tissue slices demonstrated a decreased fibrillin-1 immunoreactivity with significant downregulation of fibrillin-1 and upregulation of MMP-3. Administration of NNGH caused an enhancement of fibrillin-1 immunoreactivity. Conclusion: Among the four proteins examined, only fibrillin-1 showed distributional alterations during the wound healing process of direct-capped human dental pulp. Degradation by MMPs, together with downregulation of fibrillin-1, may be involved in the disappearance of fibrillin-1 immunoreactivity.

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Purpose: To determine the localized wear and flexural properties of resin composites for posterior lesions. Methods: Five resin composites, Clearfil AP-X (Kuraray Noritake Dental), Estelite Σ Quick (Tokuyama Dental), Estelite P Quick (Tokuyama Dental), Solare (GC), and Venus Diamond (Heraeus Kulzer, Germany), were used in the current study. Ten specimens of each resin composite were prepared in custom fixtures, and subjected to 400,000 wear machine cycles to simulate localized wear. The total maximum depth and volumetric loss of the wear facets were calculated for each specimen using a profilometer. A three-point bending test was performed to determine the flexural strength, modulus of elasticity and resilience. Values were statistically compared using one-way analysis of variance (ANOVA) followed by Tukey's Honestly Significant Difference (HSD) test. Results: The wear depth ranged from 66.9 to 134.1 μm, and the volumetric loss ranged from 0.015 to 0.074 mm³, with significant differences observed among restorative materials. The flexural strength, elastic modulus, and resilience ranged from 88.9 to 186.6 MPa, from 4.7 to 15.9 GPa, and from 7.7 to 9.7 MJ/m³, respectively. Venus Diamond, which contains nano-hybrid fillers, exhibited the highest value of flexural strength. Conclusion: The wear and flexural properties of the resin composites classified into hybrid or nano-hybrid suggested higher wear resistance and mechanical properties compared to those employing prepolymerized filler particles.

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Purpose: Preparation of a large amount of calcium hydroxide forms a dentin bridge in the early phase. However, problems due to its strong alkalinity have been pointed out, such as wide-ranging dental pulp necrosis, cleft in the dentin bridge, and porosity. On the other hand, α-TCP/Te-CP cement composed of calcium phosphate compounds is highly biocompatible and induces hard tissue. Focusing on this α-TCP/Te-CP cement, we initially analyzed the physical and engineering properties, and then investigated it histopathologically by applying this cement to the exposed surface of rat molar pulp. Methods: Using calcium carbonate and dicalcium phosphate dihydrate as bases, α-TCP/Te-CP cement powder was prepared and subjected to experiments under various conditions using orthophosphoric acid, sodium dihydrogenphosphate, and citric acid aqueous solutions as mixing solutions. Firstly, the hardening time, compressive strength, and pH behavior of the cement mixed under various conditions were measured. In addition, the solid phase involved in hardening was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, direct pulp capping was applied to the right upper first molar in Wistar rats. After 7 and 14 days, the test tooth was excised with the maxilla en bloc after perfusion fixation under general anesthesia, decalcified at a neutral pH, and stained with HE following the standard method. Results: The longest and shortest hardening times were about 52 and 2 minutes, respectively. The largest and smallest compressive strengths were about 14.7 and 0.3 MPa, respectively. The pH ranged from about 6.0 to 9.8. Transition to apatite with hardening was noted in cement mixed with orthophosphoric acid and sodium dihydrogenphosphate solutions. On histopathological examination, the formation of a dentin bridge was noted. Conclusion: α-TCP/Te-CP cement transitioned to apatite with hardening and formed a high-quality dentin bridge, compared to that formed by the calcium hydroxide preparation. The cement showed a superior ability to seal the exposed pulp surface, suggesting its usefulness as a direct pulp-capping agent.

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Purpose: Temporary restorative materials are widely used as short-term seals after cavity preparation for indirect restorations. Recently, an experimented temporary material containing S-PRG filler has been developed. The purpose of this study was to examine the marginal sealing ability of experimental temporary restoration materials. Methods: Five chemical-cured type temporary materials and three light-cured type temporary materials were used in this study. Cavity preparations were prepared, then the temporary restorative materials were condensed into the cavity according to each manufacturer's instructions. Specimens were stored in 37℃ water for 24 h (24 h group). After storage, half of each group was thermally stressed for 100 cycles at 5℃ and 55℃ (TC group). All specimens were immersed in 0.5 % basic fuchsin solution for 24 h and the degree of dye penetration was scored. Thermal expansion of the materials was also measured. Results: For the 24 h group, chemical-cured materials showed less dye penetration, then light-cured materials showed good marginal sealing. For the TC group, less dye penetration was observed for chemical-cured materials, but light-cured materials showed reduced marginal sealing. Conclusions: From the results of this study, the experimental temporary restorative materials containing S-PRG filler showed good marginal sealing with lower thermal expansion.

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Purpose: The purpose of this study was to evaluate the influence of various contaminants on the apical sealing ability and microhardness of mineral trioxide aggregate (MTA) in extracted teeth ex vivo. Methods: The root canals of 51 single-rooted human teeth were prepared and filled with laterally condensed guttapercha cones and a sealer. After root surface coating, apicoectomy and preparation of apical cavities, the teeth were randomly divided into 5 groups. Group 1 was contaminated with distilled water (control) , group 2 with saline solution, group 3 with adrenalin solution, group 4 with blood, and group 5 with EDTA solution. After filling with MTA, the teeth were subjected to a leakage test. The teeth samples were then bisected and subjected to a microhardness test, and observed by stereoscopy and scanning electron microscopy. Results: A hermetic seal was observed morphologically in group 1. However, partial sealing and gaps between dentin and MTA or lacunae in MTA were observed in groups 2-5. Group 1 showed significantly less leakage than the other groups, but there was no significant difference among the experimental groups. The microhardness of group 5 was significantly less than that of group 1. Conclusion: The results suggested that contamination of MTA while setting decreased the sealing ability of MTA.

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Objective: The aim of this study was to evaluate the effect of two slow-start curing methods on accelerating the curing of different shade resin composite at the cavity floor. Materials and Method: Clearfil Photo Bright or Palfique Estelite was placed in a teflon mold. Then the resin composite was polymerized using one of three curing techniques: 1) 600 mW/cm² for 60 s, 2) 270 mW/cm² for 10 s + 600 mW/cm² for 50 s, 3) 270 mW/cm² for 10 s + interval 5 s + 600 mW/cm² for 50 s. After light curing, the 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: 270 mW/cm² 10 s + interval 5 s + 600 mW/cm² 50 s showed a statistically greater KHN at the base of the resin composite than at the top surface for Clearfil Photo Bright (shade A3) (p<0.05). However, the slow-start curing method: 270 mW/cm² 10 s + interval 0 s + 600 mW/cm² 50 s showed a statistically higher KHN at the base of the resin composite than at the top surface for Clearfil Photo Bright (shade B4) (p<0.05). Conclusions: The slow-start curing method with 5 s interval showed much more acceleration of the curing of the resin composite at the bottom surface than that of the slow-start curing method with 0 sec interval. The light-cured resin composite which has the property of increasing the contrast ratio during polymerization showed accelerating the curing at the cavity floor. It seems to be suggested that this type of resin composite compensates for polymerization contraction stress. However, the findings indicated that the slow-start curing method with 0 sec interval showed much more acceleration for the curing of resin composite at the bottom surface for the dark shade resin composite.

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Purpose: Ozone, which is frequently used in medical fields, generates OH radicals, of which an oxidative dissolution can provide highly effective antiseptic properties with the further benefit of not allowing the emergence of resistant bacteria. In medical treatment performed through dentistry, because its effects of sterilization, anti-inflammation, and hemostasis are also emphasized, the possibilities of using ozone water to wash and sterilize dentures or periodontal pockets and as a cleaning liquid to treat root canal sites have been examined. Furthermore, other new usages of ozone are expected to be developed. However, because ozone has a short half-life, the antimicrobial properties of ozone water last for only a brief time and so its scope of application is limited. Therefore, an ozone gel has been developed to maintain its antiseptic properties for a long time and to widen the scope of its application. To assess the antimicrobial activity of the gel, we conducted experiments in vitro to assess the possibility of its use for preventing tooth caries. Methods: Using Streptococcus mutans PS-14 strains, Streptococcus sobrinus 6715 strains, and Actinomyces naeslundii ATCC19246 strains, we measured the minimum growth-inhibitory density with the 2-times serial dilution method. Furthermore, we examined their antibacterial action against resting cells in terms of changes in concentration and over time. Results: 1. The minimum inhibitory concentration against S. mutans was revealed to be 250 μg/ml. 2. The minimum inhibitory concentration against S. sobrinus was revealed to be 250 μg/ml. 3. The minimum inhibitory concentration against A. naeslundii was revealed to be 100 μg/ml. 4. The antibacterial activities were found to be a bactericidal effect against resting cells of S. mutans, S. sobrinus and A. naeslundii. Conclusions: From the above, ozone gel was found to have a prominent bactericidal effect against cariogenic bacteria, suggesting that it has an anticariogenic effect.

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Purpose: This study investigated the effect of light intensity and light-curing time on the Knoop hardness in seven dual-cured resin cements. Methods: The light intensity of an LED curing unit (Demi, Kerr, USA) through different thicknesses (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mm) of a machinable ceramic disk (Vitablocs Mark II: A2, Vita Zahnfabrik, Germany) was measured with a dental curing light meter (LED Radiometer, Demetron, USA). Seven commercial dual-cured resin cements were tested: one was total-etch (Variolink II, Ivoclar Vivadent, Liechtenstein); three were self-etch (Panavia F2.0, Kuraray Noritake Dental; Clearfil Esthetic Cement, Kuraray Noritake Dental; and NX3 Nexus Third Generation, Kerr); and three were self-adhesive (RelyX Unicem 2 Automix, 3M ESPE; Maxcem Elite, Kerr; and Clearfil SA Cement Automix, Kuraray Noritake Dental). Resin cements were condensed in a steel mold (2.0×2.0×12.0 mm), and irradiated through or not through a machinable ceramic disc of 2.0 mm in thickness. Irradiation time was set at 20 or 40 sec. Self-cured cements were not irradiated, but were left in a dark condition. Knoop hardness numbers were measured at 24 h after curing. Results were analyzed by one-way ANOVA and Tukey's post hoc test in each resin cement (α=0.05). Results: When the light-curing time was 20 sec, the presence of the ceramic disk significantly decreased the Knoop hardness in all cements except for Clearfil SA Cement (p<0.05). When the light-curing time was doubled, all the cements showed Knoop hardness similar to that obtained for the corresponding control. The Knoop hardness of all cements was significantly decreased when they were self cured (p<0.05). Conclusion: Under the present experimental conditions, light curing through a ceramic plate significantly decreased the microhardness of 6 out of 7 resin cements. The decrease of the microhardness was eliminated by extending the irradiation time.

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Purpose: Undifferentiated ectomesenchymal cells in damaged pulp tissue differentiate into odontoblasts, forming reparative dentin. Elucidation of the molecular mechanism of differentiation from undifferentiated ectomesenchymal cells into odontoblasts is critical for the development of vital pulp therapy for conservative dental treatment. The Wnt family, secreted glycoproteins, has recently attracted attention as a key factor for the differentiation of various types of cell during wound healing of pulp. The Wnt family has been demonstrated to play an important role in the formation of reparative dentin as well as in the process of tooth development. Signal transduction through the canonical Wnt/β-catenin pathway in Wnt signaling has been elucidated in detail. Lithium chloride (LiCl) inhibits the GSK3β activity of cells and promotes the accumulation of β-catenin in the nuclei, causing pseudo-activation of the canonical Wnt/β-catenin pathway. Thus, LiCl is applied to various cells to investigate the effects of Wnt. In this study, the role of the canonical Wnt/β-catenin pathway in the differentiation from undifferentiated ectomesenchymal cells into odontoblasts was examined by investigating the effects of LiCl on cultured primary dental pulp cells. Methods: Cultured primary dental pulp cells isolated from rat lower incisors were used in this study. The cells were treated with LiCl (10 mmol/l) for 2 days and cultured for 20 days. Morphological analysis of alkaline phosphatase and von Kossa stainings were performed in the cells. Total RNA isolated from the cells was used for examination of odontoblastic phenotypes including alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), osteocalcin, and ectodin with real-time PCR. Further, to examine the effects of LiCl on the Wnt/β-catenin pathway in dental pulp cells, western blotting analysis for detecting β-catenin phosphorylation in the cells was carried out. Results: Phosphorylation of β-catenin was inhibited by LiC1 in cultured pulp cells, suppressing odontoblast differentiation and mineralized dentin-like nodule formation. Expressions of ALP, DSPP, and osteocalcin mRNA were reduced by the addition of LiCl, whereas the expression of ectodin, an antagonist of Wnt and BMP, was enhanced by the addition of LiCl. Conclusion: Odontoblast differentiation and dentin formation are regulated through the canonical Wnt/β-catenin pathway involving ectodin. In addition, a negative feedback mechanism through ectodin exists in this pathway.

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Purpose: Despite routine periodontal therapy, treatment-resistant periodontitis might still progress to the advanced stage. Systemic antimicrobial administration has been chosen as one of the treatments for such periodontitis, however, there is little evidence to explain the establishment and spread of infection in such cases because the causative bacteria cannot be identified on bacteriological examination. Therefore, we studied the efficacy of systemic azithromycin administration for patients with treatment-resistant periodontitis. We analyzed the patients from their first visit throughout the duration of the study period, and evaluated the changes of clinical parameters and microbiology to provide indicators of therapeutic effects following therapy. Subjects and Methods: The subjects enrolled in this study were systemically healthy with at least 16 natural teeth and had had no periodontal or antibiotic therapy in the last 6 months. The patients had moderate to severe periodontitis, with 20% or more sites with ≥4 mm probing depth (PD ≥4 mm) or more and ≥30% sites of alveolar bone loss. Clinical measurements (PD, bleeding on probing (BOP), gingival index (GI), and tooth mobility) and whole saliva samples for bacteriology were collected at the beginning of the study. The total number of bacteria and the number of Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans in the mouth were calculated using real-time polymerase chain reaction (PCR). All the subjects underwent initial preparation including scaling and root planing (SRP) at intervals of 7-10 days, and re-examination and saliva extraction were repeated 4 weeks after SRP. Subsequently, SRP was repeated for residual sites with PD ≥4 mm and re-examination and saliva extraction were repeated 4 weeks after this procedure. Subjects with ≥30% residual sites with BOP were enrolled into the treatment-resistant periodontitis group (azithromycin group), while subjects with <30% residual BOP sites were enrolled into the healing group. Results: Five of 31 subjects were enrolled into the azithromycin group. The values of PD, GI, and BOP revealed improvement after SRP in both groups; however, the improvement in the healing group was better than that in the azithromycin group. Following azithromycin administration, the BOP values revealed improvement, and the healing was better in the azithromycin group than in the healing group. Furthermore, the ratio of P. gingivalis number compared to total bacteria number was reduced even after re-SRP in the azithromycin group. Conclusion: Our results suggest that azithromycin administration could be a favorable treatment option for patients with treatment-resistant periodontitis.

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Purpose: A nonfunctional tooth can be utilized in tooth transplantation, which could eliminate the need for dentures. Many case reports claim a good prognosis following tooth transplantation, but in most cases involving the lower jaw, the residual bone mass in the recipient site is limited. We report a case of autotransplantation of teeth to the areas close to the maxillary sinus, which helped eliminate the need for dentures. Case Report and Results: A 61-year-old woman consulted our department with the chief complaint of painful right maxillary molars. She had been diagnosed with type II diabetes mellitus (HbAlc: 6.5%) since 1996 and was receiving insulin therapy by self injection. At the initial consultation, the right maxillary first molar was extracted because of poor prognosis. In addition, preservation of the left maxillary first molar was deemed impossible because of root fracture. The patient expressed strong antipathy towards the use of dentures. Therefore, we checked the possibility of dental implant therapy and observed that the distance to the maxillary sinus base was too short to insert an implant and the sinus mucosa was swollen. We decided that implantation with sinus floor augmentation was impractical. Therefore, we opted for bilateral autotransplantation of the third mandibular molars to the maxillary arch. After the initial periodontal therapy, 48 was transplanted to the 16 region, along with inversion of the mesiodistal direction considering the distance and tooth root form in relation to the maxillary sinus base. Provisional restoration was provided for 3 months post-transplantation. After confirming the stability of the transplanted tooth, 38 was transplanted to the 26 region, and provisional restoration was provided for 3 months post-transplantation. After 29 and 22 months post-transplantation in the maxillary right and left sides, respectively, we confirmed the stability of the transplanted teeth as the final prosthesis. Discussion: In this case, with regard to transplantation to an area of severe alveolar bone resorption, we were concerned about residual alveolar bone mass, but the feasibility of transplantation was verified using cone beam computed tomography (CBCT) to measure the alveolar bone thickness and its distance from the maxillary sinus base. Using this method, a missing tooth portion was treated safely without implantation. Conclusion: In this case requiring treatment in areas close to the maxillary sinus, we demonstrated that the use of dentures can be avoided by tooth transplantation and using CBCT.

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