Purpose: Nickel-titanium (NiTi) endodontic instruments show greater flexibility than stainless-steel instruments and thus exhibit better centering ability in curved canals. Many kinds of NiTi instruments have been developed, each with their own specific design characteristics in terms of cross-sectional shape, taper, pitch, helical angle, and so forth. Moreover, several instruments are currently marketed that are manufactured using M-Wire, which is produced by applying heat treatment and exhibits increased flexibility and resistance to cyclic fatigue compared to standard NiTi wire. ProFile Vortex instruments are made of M-Wire, have different cutting flute design from ProFile instruments, and thus are claimed to show improved flexibility and fracture resistance. The aim of this study was to evaluate the mechanical properties, especially the phase transformation behavior and the bending property, of the ProFile Vortex instruments.
 Methods: In this study, ProFile Vortex instruments with size 30 tip and 0.06 taper were used, and ProFile and FlexMaster instruments of the same size were selected as controls. Phase transformation behavior of the NiTi alloy used in each instrument was estimated by determining transformation temperatures using differential scanning calorimetry. A cantilever bending test was used to measure the bending load at 0.5 mm and 2.0 mm deflection, corresponding to the elastic range and the superelastic range, respectively.
 Results: The martensitic transformation starting temperature and the reverse transformation finishing temperature for ProFile Vortex instruments were above 37°C and significantly higher than those for ProFile and FlexMaster instruments (p<0.05). The bending load values of ProFile Vortex instruments were significantly lower than those of FlexMaster instruments (p<0.05), but were not significantly different from those of ProFile instruments (p>0.05).
 Conclusion: ProFile Vortex instruments exhibited satisfactory superelasticity at the intraoral temperature, as revealed by their phase transformation behavior, and high flexibility. Thus, these instruments may offer clinical advantages in the shaping of curved canals.

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 Purpose: Our previous study revealed that resin-modified glass-ionomer cement (RMGI) as a dentin bonding system exhibited relatively stable bonding behavior to Er: YAG lased dentin. However, the obtained bond strengths of RMGI were lower than those of the bonding resin. In this study, to develop a new dentin bonding system suitable for Er: YAG-lased dentin, conditioning effects of carboxylic acid-metal salt, which is expected to reinforce the denatured layer and increase the bonding performance of RMGI to laser-affected dentin, were investigated.
 Methods: Flat dentin surfaces from freshly-extracted bovine teeth were prepared and irradiated with Er: YAG laser (Erwin Adverl) at low power (50 mJ/1 pps) or low power followed by medium power (150 mJ/1 pps). These lased dentin and non-lased dentin were conditioned with 20% polyacrylic acid+3% aluminum chloride solution (Al) or 10% citric acid+2% ferric chloride solution (Fe), followed by the placement of Fuji Lining Bond LC/Clearfil AP-X. The micro-tensile bond strengths (μTBSs) and fractomorphology were evaluated (Scheffé test, α=0.05), and cross-sectional observation of the interface was conducted under SEM.
 Results: The μTBSs to non-lased dentin without any conditioning or with Al or Fe conditioning were approximately 12 or 24 MPa respectively, leading to significant conditioning effects on bond strength to non-lased dentin (p<0.05). The μTBSs to lased dentin without any conditioning were non-quantifiable. The Al or Fe conditioning of lased dentin showed 5～6 MPa or 10～13 MPa, respectively. Fe exhibited significant conditioning effects to lased dentin (p<0.05). Microcrack formation from dentin to RMGI, mixed failure in dentin and RMGI and adhesive failure occurred characteristically in the Fe group compared to the Al group. These findings demonstrated that Fe might reinforce the denatured layer and cause strain concentration both in the denatured layer and RMGI, leading to the increase of μTBSs.
 Conclusion: The present findings revealed that the conditioning with 10% citric acid+2% ferric chloride solution might be very effective for improving the bonding performance of RMGI to Er: YAG lased dentin as a dentin bonding system.

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 Purpose: To investigate the healing effects of light-cured calcium silicate-based pulp-capping material (TCL), which was equivalent to MTA, the behavior of element transfer (P, Ca, Si and C), elution and precipitates was examined using an electron probe micro analyzer (EPMA) and inductively coupled plasma atomic emission spectrometry (ICP).
 Materials and methods: The specimens of MTA or TCL filled in standardized cylindrical holes were stored in 37°C phosphate buffered saline (PBS) for 1, 3 or 7 days. The immersed and non-immersed specimens were embedded in epoxy resin and mirror-polished longitudinal-sectional surfaces were prepared. The distribution and transfer of P, Ca, Si and C were analyzed with EPMA along the longitudinal section of the specimens. The cylindrical specimens (φ4.0 mm×2.0 mm) of MTA and TCL were suspended in 20 ml of 37°C of ultra-pure water for 1, 3 or 7 days. The elution properties per unit area of Ca and Si were measured by IPC and statistically analyzed with the t-test (α=0.05).
 Results: As for MTA, water permeation along with P infiltration occurred and was accompanied by the transfer of Ca and Si towards the surface of the specimens. These elements were continuously eluted out of the specimens as ions. As for TCL, well-marked transfer of the elements like MTA could not be observed but continuous elution of the elements occurred in an equivalent amount to MTA, which was caused by the water penetration through the highly hydrophilic monomers (polyethylene glycol dimethacrylate) in the superficial layer of TCL. Precipitates of calcium phosphate-like crystals were found on the surfaces of both MTA and TCL. These findings demonstrated that almost the same continuous elution of both Ca and Si from MTA and TCL might induce the similar excellent effects of direct capping.
 Conclusion: The present findings revealed that the behavior of element transfer, elution and precipitates in the TCL material might be almost the same as MTA, leading to similar direct pulp-capping effects.

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 Introduction: The presence of a vertical root fracture (VRF) in an endodontically treated tooth has an immense impact on the treatment outcome. Early diagnosis of a VRF is imperative to avoid overtreatment and extensive bone loss. The purpose of this study was to develop a method for the early diagnosis and protection for VRF, by investigating the clinical symptoms of VRF in endodontically treated teeth.
 Methods: Four hundred fifty-nine endodontically treated teeth in 420 patients (27-84 years old) with clinical signs and symptoms suggestive of VRF teeth were included in the study after informed consent was obtained. The 459 VRF teeth were examined and evaluated based on the clinical findings of radiography, and the condition of the post and core. A final decision on VRF was made based on dental microscope findings and surgical inspection.
 Results: VRF teeth were observed most frequently in patients aged 50-59, and the mandibular molars were the most frequently fractured. All VRF teeth were found to have percussion pain, although 20% of VRF teeth had detected the effectiveness radiographs (perilateral radiolucency, “halo” radiolucency) with confirmed fractures. A dental microscope can provide valuable diagnostic information in the detection of VRFs. Eighty percent of VRF was within one fourth short post core teeth.
 Conclusion: Percussion response and dental radiographs in routine examination after endodontics were effective for the early diagnosis of VRF, and a dental microscope can be used to make the final decision. The results of this study showed that long post core teeth had higher fracture resistance than short post core teeth in endodontically treated teeth.

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 Purpose: The periodontal ligament is present between hard tissue; the ligament is constantly under mechanical stress and is not calcified to maintain homeostasis despite having a hard-tissue-forming ability. The homeostasis of the periodontal ligament is said to exist and the ratio of TGF-β1 and BMP-2 is involved. PLAP-1 is known as a protein which controls the BMP-2, but the protein which controls the TGF-β1 is not clear. Therefore, we calculated the ratio of the amount of gene expression using microarray for cultured normal human periodontal ligament fibroblasts (hPdLF) and cultured normal human gingival fibroblasts (Gin-1), the ratio of the expression level, especially in hPdLF for high leucine significance in the periodontal ligament was not a clear leucine rich repeat containing 32 (LRRC32), tissue-derived culture cells adjacent to the periodontal ligament in order to clarify the specificity in the periodontal tissue (Gin-1, normal human dermal fibroblasts (NHDF), normal human osteoblasts (NHOst), and cultured human epithelial cells (HeLa) ) were compared and examined using RT-PCR.
 Materials and methods: Cultured hPdLF and Gin-1 from total RNA were extracted and analyzed by microarray. RT-PCR is hPdLF, Gin-1, NHDF, NHOst and HeLa from extracted and purified total RNA, and cDNA obtained by reverse transcription, GAPDH as an internal standard LRRC32, and is an indicator of calcification, Periostin, osteocalcin (OC), osteopontin (OPN), RUNX2, bone sialoprotein (BSP) and TGF-β1 by PCR.
 Results: In analysis by microarray, LRRC32 was found that is strongly expressed in hPdLF compared to Gin-1. The gene expression of LRRC32 in hPdLF of three different lots by RT-PCR was observed and was derived from soft tissue Gin-1, NHDF, NHOst, and HeLa gene expression in LRRC32 was not recognized. On the other hand, gene expression of LRRC32 was observed in NHOst from hard tissue. Expression of the gene of a marker of calcification OPN, OC, RUNX2, Osterix gene expression was observed in hPdLF, OC, RUNX2, Osterix gene expression was observed in NHOst.
 Conclusion: LRRC32 is constitutively expressed in the periodontal ligament, suggesting that it is expressed in tissues involved in hard tissue formation.

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 Purpose: One-step bonding adhesives now available on the market have a tendency to decrease the bond strength of resin to teeth when stored for a prolonged time or at a high temperature. In this study, in order to understand why the bond strength of resin to the teeth decreased, the hydrolysis of the functional methacrylate monomer utilized in one-step bonding adhesive was examined by using the nuclear magnetic resonance (¹³C NMR) technique and shear adhesive strength.
 Methods: G-BOND PLUS (G-BP, GC) used as a one-step bonding material was stored at 40°C for 0, 3, 7 and 14 weeks in an incubator to serve as a test sample.
 G-BP 300 mg and dimethyl sulfoxide (DMSO) 250 mg served as a test sample for ¹³C NMR and were weighed accurately in an NMR tube, followed by shaking and mixing before analysis by using the ¹³C NMR technique. Furthermore, the shear adhesive strength was also measured for the same storage period.
 Results: As a result, it was found that two NMR peaks, one of which belongs to the carbonyl carbon of carboxyl methacrylate and the other to the methylene carbon of ethylene glycol, were detected when G-BP solution was stored at 40°C with their augmented NMR peak strengths when the storage duration was prolonged.
 When G-BP was stored at 40°C for 14 weeks, the methacryloxy ester group of 4-MET was degraded by 13.76%; that is, the ester group of 4-MET was hydrolyzed, subsequently producing methacrylic acid, ethylene glycol and trimellitic acid.
 In addition, the bond strength to enamel was 17.20 MPa when stored for 0 days (control), but the value decreased gradually with the prolonged storage period and markedly to 12.33 MPa when stored for 14 weeks. Similar to the bond strength of enamel, the value of the bond strength to dentin decreased from 15.36 to 11.61 MPa when the storage period was prolonged. The bond strength of resin to the tooth thus seemed to decrease when 4-MET in the one-step bonding adhesives was altered by hydrolysis in response to the prolonged storage period.
 Conclusions: The bond strength of resin to the tooth substance was attributed to degradation of the functional monomer in one-step bonding adhesives, by the extension of the storage period.

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 Purpose: In endodontic therapy, understanding the anatomy of the root and root canal is necessary for successful root canal treatment. Performing a treatment while understanding the three-dimensional form using a medical CT to identify the different features of root canal anatomy is important for successful root canal treatment. The aim of this study is to identify the root and root canal morphology of maxillary first (M1) and second (M2) molars in Japanese people by a multi-detector computed tomography (MDCT) image.
 Materials and methods: We used the MDCT images of 443 Japanese (220 males, 223 females; age 20-29 years) who underwent 64-row MDCT for diagnostic purposes of oral diseases in the Department of Radiology at the hospital attached to the Nihon University School of Dentistry at Matsudo (Chiba, Japan), from January 2010 to March 2014. Teeth with extensive caries, root canal filling, restorations and metal artifacts were excluded. The root number was recorded and the root canal morphology of the mesiobuccal root (MBR), distbuccal root (DBR) and palatal root (PR) was analyzed according to Vertucci’s classification.
 Results and discussion: Three roots of M1 were observed in about 95% of both males and females. The rate of fusion root of M2 was higher than M1 (p<0.01). On the other hand, the incidence of fusion root was about 33% for males and about 53% for females in M2, and the rate of the fusion ratio in M2 of females was higher than males (p<0.01). It was suggested that the fusion root of M2 will be higher than Indian (26.8%), Chinese (18.0%), Korean (24.73%) and Brazilian (20.6%) people. In Vertucci’s classification, Type Ⅰ, the root canal does not diverge was observed in 34.1% of males and 36.7% of females in MBR of M1. In addition, about 70% of both males and females in M2. M1 was higher in the rate of 2 root canals of MBR than M2 (p<0.01). Two root canals did not join in the morphology of 2 root canals and 2 apical foramina were mostly observed. Both PR and DBR had mostly 1 root canal of Type Ⅰ.
 Conclusion: It is important to understand root canal anatomy with CT, for improving the outcome of endodontic treatment. Accessing cavity work needs to be aware of the presence of 2 root canals.

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 Purpose: Pine bark extract (FLAVANGENOL^®) functions as a scavenger of reactive oxygen species (ROS) and facilitates blood flow. However, the biological effects of FLAVANGENOL^® on periodontal tissue have not been investigated. In this study, the effects of FLAVANGENOL^® on gingival fibroblasts and periodontal ligament cells (cultured cells derived from human periodontal tissue) were investigated.
 Methods: Gingival fibroblasts and periodontal ligament cells were incubated for 3 min in growth medium in the absence or presence of 10 or 100 mg/ml FLAVANGENOL^®. After washing, cell proliferation, anti-oxidative capacity, and ATP production were determined.
 Results: Anti-oxidative capacity was detected in the presence of both 10 and 100 mg/ml FLAVANGENOL^®. The growth rate of periodontal cells was not affected by the presence of either 10 or 100 mg/ml FLAVANGENOL^® in the growth medium. Inhibition of ROS and ATP production capacity was also detected in the presence of 10 and 100 mg/ml FLAVANGENOL^®.
 Conclusion: Concentrations of FLAVANGENOL^® did not inhibit periodontal cell growth, whereas increased anti-oxidative capacity and ATP production capacity were observed. These findings suggest that FLAVANGENOL^® may be useful for metabolic activation of periodontal tissue in vitro.

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 Purpose: In an irradiated jaw, the level of cellular activation in bone decreases, and so bacterial infection is likely to cause osteomyelitis in such cases. Herein, we report a case in which conservative treatment for mandibular osteomyelitis due to periapical periodontitis of tooth 46, which developed in a patient with a history of radiation therapy for pharyngeal cancer, led to good progress.
 Case description: The patient was a 58-year-old male. Chemoradiation therapy was performed from November 2006 to January 2007. In early May 2010, the patient suffered spontaneous pain on the right side of the mandible. At a periodical examination in the Department of Otorhinolaryngology in the same period, ¹⁸F-fluoro-deoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) revealed high uptake of FDG on the right side of the mandible. The subject was diagnosed with radio-induced mandibular osteomyelitis due to periapical periodontitis of tooth 46 at the Department of Periodontics and Endodontics and Department of Oral and Maxillofacial Surgery of Okayama University Hospital. A dose of antibiotics and painkillers (non-steroid anti-inflammatory drugs) was commenced at the Department of Oral and Maxillofacial Surgery, and root canal treatment for tooth 46 was continued at the Department of Periodontics and Endodontics.
 Treatment progress: Despite continued root canal treatment for tooth 46, spontaneous pain on the right side of the mandible persisted. Furthermore, the region of percussion pain according to Yumikura symptoms spread forward from tooth 46. The patient had a history of radiation therapy to the mandible, hence surgery of the mandible was contraindicated. Accordingly, instead of surgery, the root canals of all teeth that were present in the area of edematous change in the bone marrow determined by magnetic resonance (MR) imaging, were opened. Concurrently, in addition to discontinuation of anti-cancer medication at the Department of Otorhinolaryngology, a dose of antibiotics was continued at the Department of Oral and Maxillofacial Surgery. Moreover, by keeping those teeth and the affected area rested, the acute symptoms of osteomyelitis improved. The mandible has since remained in a good condition.
 Conclusion: For radio-induced mandibular osteomyelitis due to periapical periodontitis of tooth 46, combined conservative treatment by root canal treatment and a dose of antibiotics led to good progress. The removal of oral infection under collaborative medical and dental care for patients scheduled for radiation to the jaw is important for preventing radio-induced mandibular osteomyelitis.

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