Purpose: There is a need for food products that can assure the quality of life (QOL) of elderly people who are at risk of tooth decay (particularly those who require long-term care and are unable to ensure adequate oral hygiene). In this study, we focused on maltitol, a leading alternative sweetener.
 Methods: We made maltitol-containing cookies and investigated their effect on calcification on the enamel surface layer of teeth, and also carried out a questionnaire survey regarding the test cookies. Enamel blocks for use as test materials were made from healthy premolars extracted for orthodontic reasons. Saliva (450 ml) was collected from volunteer participants. Test samples were created containing saliva only as well as saliva with the addition of 5% maltitol, 5% sucrose, flour, unsalted butter, egg yolk, baking powder, cookie dough made with maltitol, or cookie dough made with sucrose. Enamel blocks were immersed in saliva solutions for 1 week in an incubator at 37°C. Before and after immersion, their pH was measured, the surface was observed by scanning electron microscopy and contact microradiography (CMR), and calcification levels were analyzed. Double-blind taste tests were also carried out by 102 healthy adults who responded to a questionnaire.
 Results: There was almost no evidence of decalcification after immersion in saliva alone or in saliva containing 5% maltitol, flour, egg yolk, unsalted butter or baking powder. Considerable decalcification occurred after immersion in saliva containing 5% sucrose or cookie dough made with sucrose, but almost no decalcification after immersion in saliva containing cookie dough made with maltitol. Questionnaire results revealed that, though some respondents felt that maltitol-containing cookies were insufficiently sweet, they were highly satisfied with how easy they were to masticate and swallow, and a large number said they would be willing to purchase them.
 Conclusion: Our results suggest that maltitol-containing cookies may be a valuable food for preventing tooth decay, which is a major problem in elderly subjects.

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 Purpose: The aim of this study was to evaluate the polymerization shrinkage and mechanical properties of self-adhesive resin cements, and to compare them with those of conventional resin cements.
 Methods: Four commercially available self-adhesive resin cements and three conventional resin cements were used. Polymerization shrinkage was determined by using a water-filled dilatometer. Inorganic filler loading and thermal expansion were also measured. SEM observations of cured cement specimens were carried out.
 Results: The average inorganic filler contents of the self-adhesive resin cements ranged from 55.3 to 66.9 wt%, and those of conventional resin cements ranged from 63.2 to 67.9 wt%. The highest inorganic filler content was obtained from EC, whereas GL showed the lowest value of all the test materials, and these differences were statistically significant. The average coefficients of thermal expansion of the self-adhesive resin cements ranged from 37.7 to 51.6×10⁻⁶/°C, and those of conventional resin cements ranged from 37.2 to 56.5×10⁻⁶/°C. The polymerization shrinkage of the tested resin cements after 480 s ranged from 2.14 to 4.30 vol%. GL and EC showed significantly lower volume than the other resin cements. From the SEM observations, differences in filler particle size, shape, and distribution were clearly observed.
 Conclusion: From the results of this study, although polymerization shrinkage depended on the resin cement materials, self-adhesive resin cements showed similar or higher polymerization shrinkage than the conventional resin cements.

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 Purpose: The purpose of this study was to examine the influence of saliva contamination and cleaning methods on the surface free energy of ceramics and resin cement bonding.
 Methods: Lithium disilicate glass-ceramic (IPS e. max CAD, EM) plates were used. All specimens were ground with 600-grit silicon carbide paper, and then hydrofluoric acid (Ceramic Etching Gel, CE) application was carried out. The cleaned samples were randomly divided into five groups as follows: Group 1 (control) : the specimens were not contaminated, Group 2 (SC) : after saliva contamination, the surface was rinsed with tap water, Group 3 (TE) : after saliva contamination, the surface was treated with phosphoric acid (Total Etch) for 30 s, Group 4 (IC) : after saliva contamination, the surface was treated with Ivoclean for 20 s, Group 5 (CE) : after saliva contamination, the surface was subjected to additional hydrofluoric acid application. The surface free energy of the ceramic surfaces and the bond strengths of resin cement were measured.
 Results: For all of the SC group treated surfaces, γ_S^d, γ_S^p, and γ_S^h values of the SC group decreased compared with the control. On the other hand, γ_S^p and γ_S^h values of the treated group increased substantially. The control and CE groups showed relatively higher bond strength, and no significant differences were found among these three groups under different storage conditions.
 Conclusion: The results of this study indicate that a thin layer of contaminants remains on the ceramic surface after exposure to saliva, significantly impeding the bonding of the resin cement and reducing the surface free energy. Hydrofluoric acid application is an effective method of removing the contaminants and creating an effective surface for resin cement bonding.

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 Purpose: In recent years, in line with the increase of dental implantations, peri-implantitis, which is an infectious disease caused by oral bacteria such as periodontal bacteria, has been increasing rapidly. Peri-implantitis is one of the major factors that influence the prognosis of dental implants. Therefore, effective control of infection of the oral cavity with dental implants based on a bacteriological evaluation is important. This study was performed to evaluate the clinical usefulness of periodontal bacteria-related examinations for the prognostic factor for peri-implantitis.
 Methods: Among patients with previous dental implantation, 5 patients undergoing maintenance (PM) and 10 patients undergoing supportive periodontal therapy (PSPT) were examined. The examinations included measuring periodontal and peri-implant pocket probing depth, with or without bone resorption in the implant screw (BRIS) by ortho-pantomography, plasma IgG antibody titers against periodontal bacteria, and detection of periodontal bacteria in saliva (quantitative PCR assay). The data were analyzed between PM and PSPT, patients without BRIS (P without BRIS) and patients with BRIS (P with BRIS).
 Results: Significantly more patients with BRIS were undergoing PSPT than PM. Significantly more patients with plasma IgG antibody titer to Porphyromonas gingivalis (P.g-IgG titer) ≥1.68 were undergoing PSPT than PM. Also, significantly more patients with Tannerella forsythia in saliva were undergoing PSPT than PM. Significantly more patients with P.g-IgG titer≥1.68 and patients with T. forsythia in saliva were undergoing P with BRIS than P without BRIS.
 Conclusion: Periodontal bacteria-related examinations using blood and saliva may be useful as prognostic factors for peri-implantitis.

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 Purpose: The demand for tooth bleaching for teeth whitening purposes has been increasing in recent years. However, the effects of the penetration of bleaching agents into the dentin have not yet been well studied. Swept-source optical coherence tomography (SS-OCT) enables the observation of tomographic images of hard tissues in a noninvasive manner. The present study employed SS-OCT to observe the state of the inner region of the dentin before and after tooth bleaching. Furthermore, imaging information was converted into numerical data to compare SS-OCT findings with micro-Raman spectroscopy findings, thereby assessing the diffusion dynamics of hydrogen peroxide within the dentin.
 Methods: Twenty extracted teeth were used with the approval of the Ethics Committee of Showa University Medical Association (approval number 2014-039). Specimens were divided into four groups and subjected to various numbers of bleaching sessions: once (Group 1), 3 times (Group 2), 6 times (Group 3), or 9 times (Group 4). Color measurement was performed and the dentin of each tooth was observed by SS-OCT before and after bleaching with Shofu Hi-Lite, a common bleaching agent. The area across the enamel and the dentin were examined after bleaching by micro-Raman spectroscopy using the specific wavelength for hydrogen peroxide.
 Results: Examination of L*a*b* values before and after bleaching confirmed a bleaching effect on all specimens. The ΔE*ab values increased alongside the number of bleaching sessions. Comparison of graphs of absolute numbers obtained from SS-OCT images before and after bleaching showed that after bleaching, the intensity of light reflection increased at the enamel surface but decreased around the dentin-enamel junction (DEJ). Statistical analysis of numerical data generated from SS-OCT images revealed significant changes in the enamel surface and the DEJ before and after bleaching (Student’s t-test, p<0.05). Micro-Raman spectroscopy revealed that the signal intensity at 870 cm⁻¹, characteristic of hydrogen peroxide, was high at the dentin surface area.
 Conclusion: Based on the comparisons of SS-OCT and micro-Raman spectroscopy findings, we conclude that changes in SS-OCT images reflect structural changes in the dental tissues due to the penetration of peroxide. The findings of this study suggest that SS-OCT enables the safe observation of intradental tissues without radiation exposure and can serve as a novel and effective imaging tool for the assessment of bleaching effects.

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 Purpose: Teeth whitening (bleaching) has been become an indispensable procedure. However, after home bleaching, the consumption of colored foods or acidic drinks was strictly prohibited. Recently, a home bleaching agent containing polyphosphate (polyP) has been introduced into clinical practice to reduce the influence of stain accumulation or acidic effects. In this study, we used extracted human incisors to evaluate the effects of polyP on tooth bleaching, inhibition of stain accumulation and prevention of decalcification (SEM observation and Ca release).
 Methods: 35 extracted human incisors were divided into five treatment groups (n=7) : 10% sodium polyphosphate and 10% carbamide peroxide (PPa+CP), 10% sodium polyphosphate (PPa), 10% carbamide peroxide (CP), Nite White Excel (NWE) and Salivate (SA). These agents were applied to specimens for 2 h a day, for 14 times. Colorimetric measurement was performed after 14 times of bleaching. The color difference ΔE*ab was calculated by baseline L*a*b* values, and L*a*b* values after 14 times of bleaching. The preparation of specimens and treatment agents for the stain accumulation test was the same as for the bleaching effect. Another 35 extracted human incisors were divided into five groups. Stain accumulation was considered as the color difference ΔE*ab between baseline L*a*b* values and after immersion in coffee solution for 15 min. Prevention of decalcification by polyP used five extracted human maxillary central incisors. Two incisors were used for SEM observation and three incisors for capillary gel electrophoresis. The surface was treated with PPa and SA or ultra-pure water for 2 h and etched with 40 w/v% phosphoric acid (K-etchant) for 30 sec. These specimens (n=2) were observed by SEM, and diluted solution from another specimen surface (n=3) was analyzed by capillary gel electrophoresis using a cation analysis kit (Beckman Coulter).
 Results: Regarding ΔE*ab after 14 times of bleaching, NWE, PPa+CP and CP showed larger values, but no significant difference was noted between PPa+CP and NWE. Regarding stain accumulation, PPa+CP and PPa showed significantly lower ΔE*ab values than CP and SA. Regarding SEM observation, both images of the enamel surface commonly exhibited honeycomb structures attributed to hyper and lower calcified structures of the enamel prism. However, the image of the enamel surface treated by PPa showed mild decalcification. Ca²⁺ release from the enamel surface treated with polyP was 66.3% compared with that from the non-treated surface.
 Conclusion: It is suggested that the experimental teeth bleaching agent containing polyP had the same bleaching effect as conventional bleaching agent, and also prevented stain accumulation and decalcification.

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 Purpose: Estrogen has long been known as a hormone that affects the remodeling of bone tissue. Recently, its receptors were identified in odontoblasts in addition to osteoblasts and osteoclasts. However, little is known about the receptor functions of odontoblasts. Therefore, in this study, the effect of estrogen on dentinogenesis was examined histochemically using estrogen-deficient rat models.
 Materials and methods: Ninety-six 10-week-old female SD rats were used for this experiment. They were equally divided into three groups (32 each) : the OVX (Ovariectomized rats) group, the Sham group with laparotomy alone, and the OVX+E₂ group, which was administered with 20 μg/kg/day estradiol (E₂) daily from the next day after ovariectomization. All groups were bred for four weeks, and their body weights were measured daily. Thereafter, to induce reparative dentin formation, 1.0 mm-diameter cavity preparation filled with light-cured resin composite was applied to the first molars in the lower jaw on each side. Tooth samples were taken on Days 3, 7, and 14, while blood and femur samples were collected at the same time to measure estradiol levels and bone density by DEXA. Each sample was subjected to H-E staining. On Day 14, Alcian blue staining and immunohistochemical staining were performed for ER-α and ER-β. Meanwhile, in order to compare the formation of secondary dentin, calcein was administered at 3-day intervals to the groups that were not subjected to cavity formation, and the groups were monitored by fluorescence microscopy.
 Results: The OVX group showed weight gain and a decrease of estradiol levels compared to the Sham and OVX+E₂ groups. The results of DEXA and H-E staining revealed decreased bone density, presenting osteoporosis. The results of immunohistochemical staining indicated that ER-α and ER-β localized at the nucleus of odontoblasts. The amounts of reparative dentin formation were the most in the Sham group, followed by the OVX+E₂ and OVX groups. The OVX+E₂ group showed the highest formation of secondary dentin, followed by the Sham and OVX groups.
 Conclusion: The OVX group manifested osteoporosis, and the formation of reparative dentin and secondary dentin was suppressed. The OVX+E₂ group showed no trace of osteoporosis, and recovery in the amount of dentin formation was observed. These results suggest that estrogen is involved in dentinogenesis.

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 Purpose: The purpose of this study was to evaluate the antimicrobial effects and clinical efficacy of alkaline non-alcoholic type mouthrinse (Mgnakcaps DENTSAFE) which contains heated coral calcium.
 Methods: To elucidate the antimicrobial effects of heated coral calcium, we added 0.1 ml of cultured Porphyromonas gingivalis (8.5×10⁸/ml), Streptococcus mutans (7.4×10⁷/ml), Escherichia coli (9.4×10⁷/ml), Legionella pneumophila (8.0×10⁸/ml), Salmonella enterica (8.8×10⁷/ml), Staphylococcus aureus (5.0×10⁷/ml) or Vibrio parahaemolyticus (3.1×10⁷/ml) into 10 ml of heated coral calcium solution at room temperature, and measured the number of live bacteria. Next, we investigated the clinical efficacy of heated coral calcium mouthrinse. The subjects were 20 male and female volunteers ranging from 39 to 86 years old, and they were assigned to two groups and used a placebo (placebo mouthrinse group) or rinse with Mgnakcaps DENTSAFE (coral mouthrinse group) for 1 month. In each patient, probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP), plaque index (PlI) and gingival index (GI) were measured before and after the mouthrinse for 1 month. Gingival crevicular fluids were collected by sterile paper points before and after the mouthrinse and the numbers of total bacteria, Aggregatibacter actinomycetemcomitans, Prevotella intermedia and P. gingivalis were measured by the PCR-invader method.
 Results: P. gingivalis was killed after 1 min, E. coli and V. parahaemolyticus after 5 min ; S. mutans, L. pneumophila and S. enterica after 15 min ; and S. aureus after 60 min in the heated coral calcium solution. PPD, CAL, BOP, PlI and GI did not change significantly after the mouthrinse for 1 month in both groups. However, there was an improvement tendency in BOP, PlI and GI in the coral mouthrinse group. Numbers of total bacteria A. actinomycetemcomitans, P. intermedia and P. gingivalis did not change significantly after the mouthrinse for 1 month in both groups, whereas in the coral mouthrinse group, there was a reduction tendency in P. intermedia and P. gingivalis ratio%/total bacteria after the mouthrinse for 1 month.
 Conclusion: Heated coral calcium solution had bactericidal activity. There was no significant effect of heated coral calcium mouthrinse on subgingival periodontopathic bacteria and periodontal clinical parameters. However, there was an improvement tendency in BOP, PlI and GI in the coral mouthrinse group. Therefore, these results suggest a need for long-time comparative investigation using heated coral calcium mouthrinse.

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 Tri-calcium phosphate (TCP), present in some 3M ESPE products, is a functional ingredient for use in toothpaste (Clinpro toothpaste) that delivers a high concentration of fluoride and is thought to help strengthen enamel. Toothpaste with 950 ppm fluoride includes an innovative TCP technology. During manufacturing of the toothpaste, a protective barrier is created around the calcium, allowing it to coexist with the fluoride ions. When the toothpaste comes into contact with saliva during brushing, the barrier dissolves and allows the release of calcium, fluoride and phosphate on the teeth to help prevent tooth decay and remineralization of the demineralized enamel.
 Purpose: The study investigated the possible anti-caries and anti-dentin hypersensitive effect when using sodium fluoride and fTCP-containing Clinpro toothpaste.
 Methods: In the study, Clinpro toothpaste, human teeth extracted for orthodontic reasons, and artificial saliva were used. The tooth surface demineralized value, dentinal tubules occlusion rate and incorporation of elements in the treated enamel and dentin specimens with Clinpro toothpaste were evaluated. Extracted tooth enamel specimens were cycled following 15-minute Clinpro toothpaste treatment and 24-hour immersion in artificial saliva, and the test cycle was continued for 1, 4, or 8 weeks (each n=5), and then the specimens were demineralized with lactic acid, and the concentration of calcium in the demineralized solution was analyzed with EDTA titrimetric. The morphology of the toothpaste treated dentinal surface (each n=5) was examined using SEM. In addition, the incorporation of elements in the dentinal surface was also detected by EPMA (each n=3).
 Results: The elution rate of the enamel specimens was lower than that of the control specimens around the test period of 1, 4, and 8 weeks after treatment with Clinpro toothpaste. A high occlusion rate of dentinal tubules was observed with the dentin surface contrast control specimens treated with Clinpro toothpaste. Furthermore, incorporation of F, Ca and P was also detected in the dentinal surface treated with Clinpro toothpaste during the test periods.
 Conclusion: The results of these experiments suggest that the toothpaste used provides an inhibitory effect against caries and dentin hypersensitivity.

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 Introduction: Although apexification has been used to successfully treat necrotic immature permanent teeth, regardless of the presence of apical lesions, it has also been shown to be associated with reduced strength in these teeth as well as thin dentin walls. Dentin walls remain short and thin because continued root formation rarely occurs after apexification. In recent years, revascularization has been reported as a new treatment to promote root growth in necrotic immature permanent teeth. Here we report a case of revascularization treatment in a necrotic immature permanent tooth.
 Case: The patient was a 15-year-old girl with chronic apical periodontitis caused by a fractured dens evaginatus in her lower right second premolar. Informed consent regarding the therapeutic strategy was obtained before starting the treatment.
 Methods: All procedures were performed in accordance with the treatment protocols of the American Association of Endodontists.
 Results: No symptoms were evident at a 24-month follow-up after the root canal filling. A marked reduction in the size of the apical lesion was observed on radiographic examination. In addition, some hard tissue formation was observed on the dentin walls. Positive reactions to the electric pulp test and cold test were also seen.
 Conclusion: The results in this case support the findings obtained in previous studies and suggest that revascularization is useful in the treatment of necrotic immature permanent teeth. Long-term follow-up observation is planned for this case.

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