Purpose: Minimally invasive surgery (MIS) yields favorable clinical outcomes for periodontal regeneration therapy. However, there have been few reports on the histological analysis underlying these outcomes. In this study, we created periodontal defects to investigate two different surgical procedures by histological assessment in the early wound healing process.

 Results: On the experimental side, inflammatory cell infiltration disappeared earlier than on the control side. Tartrate-resistant acid phosphatase-positive cell counts for bone defects on postoperative days 3 and 5 were significantly lower on the experimental side. The number of blood vessels on postoperative days 3 and 5 was significantly larger on the experimental side.

 Conclusion: The results suggest that minimally invasive periodontal surgery can reduce the emergence of osteoclasts in the early postoperative period, enhance angiogenesis, and facilitate healing.

 Purpose: Tooth bleaching is widely performed in clinical practice. According to Goldstein, the mechanism behind tooth bleaching is the decomposition of a carbon double bond (chromatic) molecule in a discolored tooth to an achromatic substance via hydroxyl radicals generated from hydrogen peroxide. In this study, we sought to clarify the mechanism by investigating the efficacy of bleaching and time taken to activate the hydroxyl radicals generated from various concentrations of hydrogen peroxide.

 Methods: Hydrogen peroxide solutions containing 3%, 10%, 20%, and 30% hydrogen peroxide were mixed with a spin trapping agent. The hydroxyl radicals generated were measured by electron spin resonance. Activation was achieved by light irradiation at a wavelength of 440 nm for 0.5, 1, 2, 3, 5, and 10 min. Filter papers dyed with β-carotene were immersed in 3%, 10%, 20%, and 30% hydrogen peroxide solutions and irradiated for 0.5, 2, and 10 min. The color difference, ΔE*ab, was calculated from the CIELab values at baseline and after bleaching.

 Results: The generation of hydroxyl radicals increased at higher concentrations of hydrogen peroxide and longer irradiation times. The ΔE*ab values also showed the same tendency as the results showing the amounts of hydroxyl radicals generated. That is, the ΔE*ab value increased as the concentration and activation time increased.

 Conclusions: The concentration of hydrogen peroxide and the activation time were important for the generation of hydroxyl peroxide radicals. However, based on the amount of hydroxyl radicals and the ΔE*ab values, other factors such as the catalysts, temperature rise, and the physical properties of the bleaching agent appear to be related to the efficacy. To pursue effective and safe tooth bleaching materials, other factors in addition to the concentration of hydrogen peroxide and the application time should be considered.

 Purpose: One-step self-etch adhesives (G-Bond Plus) based on 10-methacryloyloxydecyl dihydrogen phosphate (MDP) have become widely utilized due to their simplicity of application. The aim of this study was to determine the type of molecular species of calcium salts of MDP (MDP-Ca salts) that form to understand the layering mechanism of MDP-Ca salts.

 Methods: Bovine crown enamel particles or bovine crown dentin particles of 0.200 g were suspended in 1.000 g of G-Bond Plus, and the suspensions were vibrated for 1, 30, or 60 minutes. After centrifuging these suspensions, solid-state ³¹P NMR spectra of the supernatant solution of adhesives were observed using an EX-270 spectrometer. The enamel and dentin reactants of G-Bond Plus (MDP-based) were analyzed using phosphorous-31 nuclear magnetic resonance (³¹P NMR) and X-ray diffraction (XRD) techniques. Curve-fitting analyses of the corresponding ³¹P NMR spectra were performed by assuming that DCPD with an amorphous phase was also produced along with several types of MDP-Ca salts synthesized previously.

 Results: The curve-fitting analyses of each ³¹P NMR spectrum of enamel and dentin reactants of G-Bond Plus were performed. The curve-fitting analyses demonstrated that enamel and dentin developed several types of MDP-Ca salts and amorphous DCPD during decalcification. The peak intensity of MDP that had been consumed yielding several types of MDP-Ca salts was determined by totaling the relative intensity ratios of the simulated peaks for each MDP-Ca salt in each group. The amounts of MDP-Ca salts and DCPD produced by the enamel or dentin differed with reaction time. MDP was utilized in all of the all-in-one adhesives. The curve-fitting analyses demonstrated that enamel and dentin developed four types of MDP-Ca salts and amorphous DCPD during decalcification.

 Conclusion: The molecular species of MDP-Ca salts produced by enamel and dentin were mono-calcium salts of MDP-monomer and MDP-dimer, and di-calcium salts of MDP-monomer and MDP-dimer.

 Objective: A Reciproc nickel-titanium (Ni-Ti) file was designed specifically for preparing root canals with only one file under reciprocating motion. Although Reciproc is used to form a root canal with the X Smart Plus drive system, a Reciproc-specific handpiece (RECIPROC Direct) that can be connected to a dental unit was developed. The purpose of this study was to clarify the relationship between the rotational speed and transportation of the root canal using RECIPROC Direct. This study aimed to compare the cutting effect of Reciproc due to the difference in driving system between RECIPROC Direct and X Smart Plus.

 Materials and methods: Sixty simulated resin block canals with angle of curvature ranging 30°were divided according to the Ni-Ti driving system used for canal preparation into three groups of 20 samples each: experiment group 1 (EX1: RECIPROC 20,000 rpm), experiment group 2 (EX2: RECIPROC 15,000 rpm) with different rotational speed, and X Smart Plus as a control group. The preparation time was recorded, and all canals were scanned using an Olympus SZX16 and digital camera DP71 system before and after instrumentation to evaluate canal wall and canal central axis transportation at 1, 2, 3, 5 and 8 mm from the apex. The significance level was set at p<0.05.

 Results: Analysis of root canal wall displacement of the experimental group and the control group showed that the amount of displacement on the inner side in EX1 increased compared to that in the control group and the amount of displacement on the outer side decreased. On the other hand, in EX2, the amount of displacement on the inner side decreased and the amount of displacement on the outer side were the same, as compared with the control group. As a result of measuring the central axis transportation, EX1 was transported to the inner side, but in EX2, the transportation amount was small. The root canal formation time in EX 1 was 34.4±3.8 s, in EX 2 was 55.9±8.4 s, and in the control group was 44.6±3.8 s.

 Conclusion: As a result of comparing the cutting effects of Reciproc using RECIPROC Direct and X Smart Plus, it was shown that RECIPROC Direct influences the root canal morphology due to the difference in rotational speed. It was concluded that root canal formation of Reciproc using RECIPROC Direct maintains the anatomical root canal morphology by setting the rotational speed at 15,000 rpm.

 Purpose: This cross-sectional study investigated the association between severity of periodontal disease, dental and medical conditions, and maximum carotid intima-media thickness (max-IMT).

 Methods: Fifty-two subjects with a diagnosis of dyslipidemia, receiving carotid ultrasound examination, were recruited in the study at the Health Sciences University of Hokkaido Hospital. The results of clinical dental examination (number of teeth, percentage of teeth with probing pocket depth (PPD) ≥4 mm, 6 mm, bleeding on probing sites, mean PPD, periodontal inflamed and epithelial surface area, Eichner’s index), and medical or serum lipid parameters (sex, age, smoking habit, diabetes mellitus, body mass index, total cholesterol, high-density lipoprotein (HDL), non HDL, low-density lipoprotein, triglycerides) were collected. Correlation analysis, chi-square or Fisher’s exact test and then multiple linear and binary logistic regression analyses were performed to identify factors associated with max-IMT.

 Results: Regarding Spearman’s rank correlation coefficient, max-IMT was significantly associated with mean PPD, moderate and severe periodontal parameters. In the results of multiple linear regression analysis, number of teeth (partial regression coefficient (β) =−0.014, 95% confidence interval (CI) =−0.024 to −0.003, p=0.014) and HDL (β=−0.005, 95%CI=−0.008 to −0.002, p=0.003) ) were significantly associated with decreased max-IMT. In the chi-square or Fisher’s exact test, dichotomized max-IMT (≥1.1 mm and <1.1 mm) was significantly associated with the percentage of teeth with PPD≥6 mm (more than 50 versus less than 50 percentile). In the results of binary logistic regression analysis, there was a significant association between max-IMT≥1.1 mm and percentage of teeth with PPD≥6 mm (more than 50 versus less than 50 percentile) (odds ratio (OR) =8.275, 95%CI=1.462-46.844, p=0.017). The max-IMT≥1.1 mm was associated, though not significantly, with male sex (OR=4.196, 95%CI=0.914-19.252, p=0.065).

 Conclusion: This study demonstrated that tooth loss or severe periodontitis was independently associated with increased max-IMT in patients with dyslipidemia.

 Purpose: When performing dental treatment, we need to consider the general conditions of patients who are allergic to antibiotics, who have a history of asthma, and who suffer from Type 2 diabetes, especially when performing surgical treatment for these patients. We applied Kampo medicine (Hainosankyuto, Rikkosan) to these patients and performed surgical dental treatment. Here, we report the cases and treatment procedure.

 Case 1: A 48-year-old woman who complained about repeated gingival swelling in the left maxillary second incisor region. Radiographic examination showed bone resorption in the periapical region. Informed consent regarding the treatment plan was obtained before starting treatment. As she was allergic to antibiotics, Hainosankyuto was administered before the operation to prevent surgical site infection. After root canal treatment of the left maxillary second incisor, apical surgery was performed according to the Wassmund method. No surgical site infection occurred after the operation. At the 6-month recall point, radiographic examination revealed osseous healing of the peri-apical radio-opacity.

 Case 2: A 28-year-old woman who complained about repeated gingival swelling in the right maxillary first incisor region. Radiographic examination revealed peri-apical radiolucency. Informed consent regarding the treatment plan was obtained before treatment. As she was a lactating patient and wished to avoid antibiotics, Hainosankyuto was administered before the operation to prevent surgical site infection. After root canal treatment of the right maxillary first incision, abscess incision was performed to remove granulation tissue and debris. No surgical site infection occurred after the operation. At the 3-month recall point, radiographic examination showed osseous healing of the peri-apical radio-opacity.

 Case 3: A 52-year-old man who complained about gingival swelling and bleeding after brushing. At the first visit, the percentage of teeth with PD≥4 mm was 97%. The rate of teeth with BOP was 100% and O’Leary’s PCR was 100%. Inflammation was observed in the gingiva. Radiographic examination showed moderate horizontal bone resorption of teeth. Informed consent regarding the treatment plan was obtained before treatment. As he suffered from type 2 diabetes (HbA1c=6.5%), Hainosankyuto was administered before a flap operation to prevent surgical site infection. An initial periodontal treatment, including tooth brushing instruction, dental scaling and root planing was performed. Surgical periodontal therapy was performed to the sites with PD≥5 mm at the re-examination. No surgical site infection occurred after the operation. The patient’s clinical parameters are currently stable.

 Conclusion: Application of Kampo medicine, such as Hainosankyuto and Rikkosan, in oral surgery is gentle for idiosyncratic patients, including patients allergic to antibiotics, lactating patients and diabetic patients.