There are two pathways by which periodontal disease affects systemic health: local periodontal lesion-derived bacteria, inflammatory cytokines and mediators that affect distant tissues via systemic circulation and the gastrointestinal tract; and periodontal disease-derived tooth upset and loss, poor eating habits with reduced chewing ability due to occlusal pain, and nutritional status. This review examines whether the restoration of chewing function by periodontal treatment contributes to glycemic control and other whole-body health. We conducted a philological study with a particular focus on dietary habits and nutritional improvement. Regarding the relationship between chewing ability and glycemic control in patients with periodontal disease, it is considered that periodontal disease improvement is important for systemic health, including glycemic control by improving chewing function by periodontal treatment, although there is currently little evidence. Regarding eating habits and nutrition as risk factors for periodontal disease, inappropriate dietary intake associated with deterioration of chewing function, i. e., deterioration of dietary balance and eating habits, promotes gingival inflammation and dysbiosis of oral flora, suggesting that periodontal disease is a risk factor. On the other hand, intake of anti-inflammatory foods has been shown to reduce periodontal tissue inflammation regardless of plaque adhesion or the presence or absence of oral cleaning, and anti-inflammatory healthy eating patterns may enhance the effectiveness of standard oral cleaning and periodontal treatment. In fact, a program that combines improving lifestyle eating habit and periodontal disease care in collaboration with medical and dental departments has been shown to significantly improve glycemic control along with clinical symptoms of periodontal disease. From the above, when periodontal disease is viewed from the perspective of lifestyle-related diseases, it is necessary to give guidance on dietary habits and dietary nutrition in response to the risk factors for the progression of periodontal disease. In addition, periodontal disease and diabetes have a bidirectional relationship, and dietary guidance related to improving masticatory function from both perspectives is considered reasonable from the viewpoint of disease burden.

 Purpose: Recently, single-shade composite resins (CRs) with color-matching ability have been developed to simplify the shade-taking for direct composite restoration. One of the problems with CR is discoloration caused by pigmented foods, drinks, and saliva, but there are few reports on the evaluation of color stability of single-shade CRs with color-matching ability. In this study, the color stability of single-shade CRs with color-matching ability and conventional CRs were evaluated by toothbrush abrasion test and immersion test.

 Method: As six single-shade CRs, Omnichroma (Tokuyama Dental, OMC), Omnichroma Flow (Tokuyama Dental, OMF), Beautifil Unishade (Shofu, BUN), Clearfil Majesty ES Flow Universal U (Kuraray Noritake Dental, CLM), Clearfil Majesty ES Flow Universal UD (Kuraray Noritake Dental, CLD), and Clearfil Majesty ES Flow Universal UW (Kuraray Noritake Dental, CLW), six conventional CRs as the control group, Estelite Σ Quick (Tokuyama Dental, EST), Estelite Universal Flow (Tokuyama Dental, ESF), Beautifil Ⅱ (Shofu, BFⅡ), Beautifil Flow Plus X (Shofu, BFF), Clearfil Majesty ES-2 (Kuraray Noritake Dental, CMP) and Clearfil Majesty ES Flow (Kuraray Noritake Dental, CMF) were used in this study. For these 12 types of CRs, samples for the abrasion group and the non-abrasion group were prepared, and the color difference ΔE^*ab was calculated by immersing the samples in coffee and distilled water for 28 days. In addition, other samples were prepared, and water sorption and water solubility were calculated by immersing the samples in distilled water for 28 days.

 Results: In the coffee immersion experiment, BUN containing S-PRG filler showed significantly higher ΔE^*ab values in both the non-abrasion and abrasion groups after 28 days of immersion compared to the other CRs (p<0.05). Also, when comparing ΔE^*ab values between the non-abrasion and abrasion groups for each CR in the coffee immersion experiment, CLM, CLW, EST, ESF, BFF, and CMP in the non-abrasion group showed significantly higher values than the abrasion group after 28 days of immersion (p<0.05). On the other hand, the distilled water immersion experiment showed no significant difference in ΔE^*ab values between all CRs and between the non-abrasion and abrasion groups for each CR (p>0.05). Water sorption was significantly higher in BFF than in the other CRs (p<0.05) and was negatively correlated with inorganic filler content. Water solubility was highest for CMP with a significant difference (p<0.05) compared to CLM, CLD, CLW, and CMF, but there was no correlation with inorganic filler content.

 Conclusion: BUN containing S-PRG filler showed noticeable higher ΔE^*ab values in the coffee immersion experiment, suggesting that the color stability of single-shade CRs is affected not only by the resin component but also by the filler properties.

 Purpose: The purpose of this study was to evaluate the total preparation time, the pushing and pulling forces, and the amount of canal transportation after preparing curved root canal resin models using the full length technique (single length technique: NF) or crown down technique (NC) with nickel titanium (Ni-Ti) rotary instrumentation (NEX NiTi FILE Ms: NEX).

 Methods: Transparent resin models which had curved root canals of 30 degrees were used for root canal preparation with NF, NC and stainless-steel K-files (SSK) (n=9 per group). The total preparation time and the pushing and pulling forces during preparation were measured. Photographs taken before and after preparation of the root canal were superimposed. The amount of root canal transportation was measured at 1-mm intervals from the apical foramen to the 8-mm level. The data were subjected to one-way analysis of variance followed by Bonferroni or Games-Howell multiple comparison tests (p<0.05).

 Results: The average total preparation time was significantly shorter in NF and NC than in SSK, but there was no significant difference between NF and NC. The average pushing and pulling forces were significantly lower in both NF and NC than in SSK, but there was no significant difference between NF and NC. There were significant differences in the amount of canal transportation between NF and SSK at positions 0, 1, 2, 4, 5, 7 and 8 mm; between NC and SSK at 0, 1, 2, 7 and 8 mm; but no significant differences between NF and NC at any position.

 Conclusion: Both the single length technique using NEX and the crown down technique of root canal preparation were able to properly enlarge and form the curved root canal better than SSK. The results also showed that the single length technique using NEX was effective in introducing a new root canal formation method using Ni-Ti files from the existing method using SSK.