Genetic analysis of impaired healing responses after periodontal therapy in type 2 diabetes: Clinical and in vivo studies.

OBJECTIVE: This study aims to investigate the mechanisms underlying the impaired healing response by diabetes after periodontal therapy. BACKGROUND: Outcomes of periodontal therapy in patients with diabetes are impaired compared with those in patients without diabetes. However, the mechanisms underlying impaired healing response to periodontal therapy have not been sufficiently investigated. MATERIALS AND METHODS: Zucker diabetic fatty (ZDF) and lean (ZL) rats underwent experimental periodontitis by ligating the mandibular molars for one week. The gingiva at the ligated sites was harvested one day after ligature removal, and gene expression was comprehensively analyzed using RNA-Seq. In patients with and without type 2 diabetes (T2D), the corresponding gene expression was quantified in the gingiva of the shallow sulcus and residual periodontal pocket after non-surgical periodontal therapy. RESULTS: Ligation-induced bone resorption and its recovery after ligature removal were significantly impaired in the ZDF group than in the ZL group. The RNA-Seq analysis revealed 252 differentially expressed genes. Pathway analysis demonstrated the enrichment of downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. PPARα and PPARγ were decreased in mRNA level and immunohistochemistry in the ZDF group than in the ZL group. In clinical, probing depth reduction was significantly less in the T2D group than control. Significantly downregulated expression of PPARα and PPARγ were detected in the residual periodontal pocket of the T2D group compared with those of the control group, but not in the shallow sulcus between the groups. CONCLUSIONS: Downregulated PPAR subtypes expression may involve the impaired healing of periodontal tissues by diabetes.

Improvement of periodontal parameters following intensive diabetes care and supragingival dental prophylaxis in patients with type 2 diabetes: A prospective cohort study.

AIM: This study aimed to investigate the effects of diabetes care on periodontal inflammation. MATERIALS AND METHODS: This prospective cohort study included 51 Japanese patients with type 2 diabetes who underwent intensive diabetes care including educational hospitalization and regular outpatient treatment for 6 months. Dental prophylaxis without subgingival scaling was provided three times during the observational period. Associations between changes in periodontal parameters and glycaemic control levels were evaluated using multiple regression analysis. RESULTS: Overall, 33 participants (mean age: 58.7 ± 12.9) were followed up for 6 months. At baseline examination, 82% were diagnosed with Stage III or IV periodontitis. Haemoglobin A1c (HbA1c) level changed from 9.6 ± 1.8% at baseline to 7.4 ± 1.3% at 6 months. The ratio of probing pocket depth (PPD) ≥4 mm, bleeding on probing (BOP), full-mouth plaque control record (PCR), periodontal epithelial surface area (PESA) and periodontal inflamed surface area (PISA) also significantly improved. The reduction in PPD and PESA was significantly associated with changes in both HbA1c and fasting plasma glucose (FPG) levels, and the reduction in PISA was significantly associated with an improvement in FPG after adjusting for smoking, change in body mass index and full-mouth PCR. CONCLUSIONS: This is the first study to report a significant improvement in PPD and BOP after intensive diabetes care and dental prophylaxis without subgingival scaling. CLINICAL TRIAL REGISTRATION NUMBER: UMIN000040218.

Enhanced periodontal tissue healing via vascular endothelial growth factor expression following low-level erbium-doped: yttrium, aluminum, and garnet laser irradiation: In vitro and in vivo studies.

BACKGROUND: This study aimed to investigate the effects of low-level erbium-doped: yttrium, aluminum, and garnet (Er:YAG) laser irradiation on periodontal tissue healing and regeneration through angiogenesis in vivo and in vitro studies. METHODS: Intrabony defects were surgically created in the bilateral maxilla molar of rats. The defects were treated by open flap debridement (OFD) with Er:YAG laser, including low-level laser irradiation (LLLI) to bone and blood clot surfaces, or conventional procedures. The mRNA expression of vascular endothelial growth factor (VEGF) in the surgical sites was quantified using real-time polymerase chain reaction. The decalcified specimens were prepared for histometric analysis. Also, LLLI was performed on human umbilical vein endothelial cells to evaluate the effects on angiogenesis. Cell proliferation, VEGF expression, and tube formation were assessed. In addition, capsazepine (CPZ), a selective inhibitor of transient receptor potential vanilloid 1 (TRPV1), treatment was performed before LLLI for the same assays. RESULTS: OFD using Er:YAG laser did not generate thermal damage on bone or root surfaces. LLLI accelerated hemostasis by coagulation of the superficial layers of blood clots in the laser-treated group. Postoperative healing was sound in all animals in both groups. VEGF expression and bone formation were significantly increased in the laser-treated group compared to those in the conventional treatment group. In vitro, cell proliferation and VEGF expression were significantly increased in the LLLI group compared to the control group. Tube-formation assays showed that LLLI significantly promoted angiogenesis. CPZ treatment significantly suppressed VEGF expression and tube formation following LLLI. CONCLUSIONS: This study suggests that Er:YAG laser irradiation may promote periodontal tissue healing by enhancing angiogenetic effect of endothelial cells via TRPV1.

Influence of Reactive Oxygen Species on Wound Healing and Tissue Regeneration in Periodontal and Peri-Implant Tissues in Diabetic Patients.

Diabetes mellitus (DM) is associated with periodontal disease. Clinically, periodontal treatment is less effective for patients with DM. Oxidative stress is one of the mechanisms that link DM to periodontitis. The production of reactive oxygen species (ROS) is increased in the periodontal tissues of patients with DM and is involved in the development of insulin resistance in periodontal tissues. Insulin resistance decreases Akt activation and inhibits cell proliferation and angiogenesis. This results in the deterioration of wound healing and tissue repair in periodontal tissues. Antioxidants and insulin resistance ameliorants may inhibit ROS production and improve wound healing, which is worsened by DM. This manuscript provides a comprehensive review of the most recent basic and clinical evidence regarding the generation of ROS in periodontal tissues resulting from microbial challenge and DM. This study also delves into the impact of oxidative stress on wound healing in the context of periodontal and dental implant therapies. Furthermore, it discusses the potential benefits of administering antioxidants and anti-insulin resistance medications, which have been shown to counteract ROS production and inflammation. This approach may potentially enhance wound healing, especially in cases exacerbated by hyperglycemic conditions.

Impaired dental implant osseointegration in rat with streptozotocin-induced diabetes.

OBJECTIVE: Few studies have reported on the impact of oxidative stress on the dental implant failure. The aim of this study was to investigate the impact of hyperglycemia-induced oxidative stress on dental implant osseointegration in diabetes mellitus (DM). METHODS: Acid-treated titanium implants were bilaterally placed in the maxillary alveolar ridge of streptozotocin-induced diabetic (DM group) and control rats after extraction of first molars. Histological analysis and micro-push-out test were performed 4 weeks after surgery. Oxidative stress and osteogenic markers in the surrounding bone were quantified by real-time polymerase chain reaction. In the in vitro study, rat bone marrow-derived mesenchymal stem cells (BMMSCs) were cultured on acid-treated titanium discs in a high-glucose (HG) or normal environment. Intracellular reactive oxygen species (ROS), cell proliferation, alkaline phosphatase (ALP) activity, and extracellular calcification were evaluated following antioxidant treatment with N-acetyl-L-cysteine (NAC). RESULTS: The implant survival rate was 92.9% and 75.0% in control and DM group, respectively. Bone-implant contact and push-out loads were significantly lower in the DM group. Expression of superoxide dismutase 1 at the mRNA level and on immunohistochemistry was significantly lower in the DM group. In vitro experiments revealed that the HG condition significantly increased ROS expression and suppressed the proliferation and extracellular calcification of BMMSCs, while NAC treatment significantly restored ROS expression, cell proliferation, and calcification. The ALP activity of both groups was not significantly different. CONCLUSION: In diabetes, high-glucose-induced oxidative stress downregulates proliferation and calcification of BMMSCs, impairing osseointegration and leading to implant failure.

Antioxidant effect of enamel matrix derivative for early phase of periodontal tissue regeneration in diabetes.

BACKGROUND: Diabetes involves metabolic disorders in various tissues via hyperglycemia-induced oxidative stress. This study aimed to investigate the antioxidative effect of enamel matrix derivative (EMD) on periodontal regeneration in diabetes. METHODS: Twenty-two rats were equally divided into streptozotocin (STZ)-induced diabetes or control group. Two months after induction of hyperglycemia, systemic oxidative stress was measured using urinary 8-hydroxy-2'-deoxyguanosine. EMD or saline was applied into the intrabony defects created in the bilateral maxillary molar. mRNA expressions of inflammatory and oxidative stress markers were quantified (n = 6). Histometric analyses and immunohistochemistry of superoxide dismutase-1 (SOD-1) were performed 7 days postoperatively (n = 5). For in vitro experiments, the bone marrow-derived mesenchymal stem cells were isolated from rat femur and cultured in a high glucose (HG) or control medium. Reactive oxygen species (ROS) measurement and alizarin red staining were performed with/without EMD. RESULTS: Systemic oxidative stress was significantly higher in the diabetic group. The connective tissue attachment and cementum formation were significantly increased at EMD-treated sites in both diabetic and non-diabetic groups. The expression of nicotinamide adenine dinucleotide phosphate oxidase two and four was significantly lower at EMD-treated sites than at EMD-untreated sites in both diabetic and non-diabetic rats. Immunohistochemistry showed significantly higher SOD-1 expression at the EMD-treated site. In vitro, HG culture had significantly higher ROS production compared with control, which was downregulated by EMD. EMD treatment significantly recovered the impaired calcification in HG. CONCLUSION: EMD promoted early-phase wound healing and periodontal tissue regeneration in the surgically created bony defect of STZ-induced diabetic rat by suppressing hyperglycemia-induced oxidative stress.

Metformin accelerates wound healing by Akt phosphorylation of gingival fibroblasts in insulin-resistant prediabetes mice.

BACKGROUND: This study aimed to investigate the effects of metformin on gingival wound healing in insulin-resistant prediabetes. METHODS: C57BL/6J mice were fed normal diet (ND) or high-fat diet (HFD) for 10 weeks; half of the HFD mice were treated with metformin (HFD+ Met) for the last 2 weeks. Insulin and glucose tolerance tests were performed. The palatal gingiva (2.0 × 0.5 mm) was surgically removed adjacent to the maxillary molars. Post-surgical wound closure was histomorphometrically evaluated for 1 week. The mRNA expression of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in the tissue were quantified by real-time polymerase chain reaction. In vitro, the proliferation and migration of human gingival fibroblasts (HGFs) cultured under high-glucose or control conditions with/without metformin were analyzed. Akt phosphorylation and VEGF expression following the insulin stimulation were evaluated with/without metformin in high-glucose or control media. RESULTS: HFD mice showed significantly higher plasma glucose levels and insulin resistance than ND mice. Gingival wound healing was delayed in HFD group compared with ND group but significantly improved in HFD + MET group. The decreased expression of VEGF and eNOS in HFD group was significantly elevated in the HFD + MET group. The proliferation and migration of HGFs were significantly impaired in high-glucose conditions compared with control; metformin treatment partially attenuated these effects. Metformin treatment significantly recovered the downregulated Akt phosphorylation and VEGF expression in high-glucose conditions. CONCLUSIONS: Metformin improved delayed gingival wound healing in insulin-resistant prediabetes by accelerating HGFs proliferation and migration via Akt phosphorylation in insulin signaling pathway.

Effects of Antioxidant in Adjunct with Periodontal Therapy in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis.

This review investigated whether the adjunctive use of antioxidants with periodontal therapy improves periodontal parameters in patients with type 2 diabetes. A systematic and extensive literature search for randomized controlled trials (RCTs) conducted before April 2021 was performed on the PubMed, Cochrane Library, and Web of Science databases. The risk of bias was assessed using the Cochrane risk-of-bias tool. A meta-analysis was performed to quantitatively evaluate the clinical outcomes following periodontal therapy. After independent screening of 137 initial records, nine records from eight RCTs were included. The risk-of-bias assessment revealed that all RCTs had methodological weaknesses regarding selective bias, although other risk factors for bias were not evident. This meta-analysis of two RCTs showed that periodontal pocket depths were significantly reduced in the groups treated with combined non-surgical periodontal therapy and melatonin than in those treated with non-surgical periodontal therapy alone. The present systematic review and meta-analysis suggest that the adjunctive use of melatonin, resveratrol, omega-3 fatty acids with cranberry juice, propolis, and aloe vera gel with periodontal therapy significantly improves periodontal disease parameters in patients with type 2 diabetes, and melatonin application combined with non-surgical periodontal therapy might significantly reduce periodontal pocket depth. However, there are still limited studies of melatonin in combination with non-surgical periodontal therapy in Type 2 diabetic patients, and more well-designed RCTs are required to be further investigated.

Association of periodontal pocket area with type 2 diabetes and obesity: a cross-sectional study.

INTRODUCTION: The aim was to investigate the relationship of full-mouth inflammatory parameters of periodontal disease with diabetes and obesity. RESEARCH DESIGN AND METHODS: This cross-sectional study conducted diabetes-related examinations and calculated periodontal inflamed and epithelial surface area (PISA and PESA) of 71 Japanese patients with type 2 diabetes. Multiple linear regression analyses were performed to evaluate associations between PISA or PESA and diabetes and obesity parameters. RESULTS: Median value of body mass index (BMI), hemoglobin A1c (HbA1c) level, fasting plasma glucose (FPG) level, and visceral fat area (VFA) were 25.7 kg/m2, 9.1%, 151 mg/L, and 93.3 cm2, respectively. PISA and PESA were significantly associated with HbA1c after adjusting for age, sex, BMI, smoking status, and full-mouth plaque control level (PISA: coefficient=38.1, 95% CI 8.85 to 67.29, p=0.001; PESA: coefficient=66.89, 95% CI 21.44 to 112.34, p=0.005). PISA was also significantly associated with the highest FPG tertile (>175 mg/dL) after adjusting for confounders (coefficient=167.0, 95% CI 48.60 to 285.4, p=0.006). PISA and PESA were not significantly associated with BMI or VFA. CONCLUSION: PISA was associated with FPG and HbA1c, but not with obesity parameters, independent from confounders such as full-mouth plaque control level in patients with type 2 diabetes.