The Microbiome in Periodontitis and Diabetes.

Objectives: To perform a comprehensive and integrative review of the available literature on the potential changes in the microbiome of healthy and individuals with diabetes under periodontal health and disease. Materials and Methods: The review was conducted by two independent reviewers. Indexed electronic databases (PubMed/Medline, Cochrane Library, Web of Science and Scopus) were searched, including articles published in English and dated from 5 years ago until December 2021. A manual search also was performed to identify co-related articles. Following the removal of duplicates and eligibility criteria, the articles were included in tables for analysis and described in the manuscript. Results: According to this review, diabetes mellitus was associated with significant changes in the subgingival and salivary microbiome, either in its association with periodontitis or in cases of periodontal health. In addition to affecting microbial diversity in terms of taxonomy, metagenomic studies have shown that this endocrine disorder may also be directly related to increased pathogenicity in the oral microbiome. Conclusion: Although the reviewed studies demonstrate important differences in the subgingival and salivary microbiome composition because of diabetes mellitus, further studies are needed to clarify the real effects of hyperglycemia on oral microbial profiles and support new diagnostic approaches and innovative treatments.

A.actinomycetemcomitans-induced periodontal disease promotes systemic and local responses in rat periodontium.

AIM: To characterize the histologic and cellular response to A. actinomycetemcomitans (Aa) infection. MATERIAL & METHODS: Wistar rats infected with Aa were evaluated for antibody response, oral Aa colonization, loss of attachment, PMN recruitment, TNF-α in the junctional epithelium and connective tissue, osteoclasts and adaptive immune response in local lymph nodes at baseline and 4, 5 or 6 weeks after infection. Some groups were given antibacterial treatment at 4 weeks. RESULTS: An antibody response against Aa occurred within 4 weeks of infection, and 78% of inoculated rats had detectable Aa in the oral cavity (p < 0.05). Aa infection significantly increased loss of attachment that was reversed by antibacterial treatment (p < 0.05). TNF-α expression in the junctional epithelium followed the same pattern. Aa stimulated high osteoclast formation and TNF-α expression in the connective tissue (p < 0.05). PMN recruitment significantly increased after Aa infection (p < 0.05). Aa also increased the number of CD8(+) T cells (p < 0.05), but not CD4(+) T cells or regulatory T cells (Tregs) (p > 0.05). CONCLUSION: Aa infection stimulated a local response that increased numbers of PMNs and TNF-α expression in the junctional epithelium and loss of attachment. Both TNF-α expression in JE and loss of attachment was reversed by antibiotic treatment. Aa infection also increased TNF-α in the connective tissue, osteoclast numbers and CD8(+) T cells in lymph nodes. The results link Aa infection with important characteristics of periodontal destruction.

Hyaluronan does not improve bone healing in critical size calvarial defects in rats: a radiographic evaluation

Aim: This study evaluated radiographically the effects of 1% hyaluronan in bone healing using a critical size rat-calvaria defect model. Methods: Thirty adult male Wistar rats were used in this study. Two 6-mm-diameter critical-size defects were created and the treatments were randomly distributed as follows: 1) 1% hyaluronan; 2) 1% hyaluronan soak loaded onto an absorbable collagen sponge (ACS) carrier; 3) saline; and 4) ACS alone. The animals were sacrificed at 4 and 8 weeks when biopsies were collected and radiographs obtained using a direct digital radiograph system and a standardized protocol. A blind examiner evaluated the radiographic density of the images twice and an intra class correlation was performed to evaluate examiner reproducibility (R2=0.99, p<0.001). Comparisons between 4 and 8 weeks of treatment were performed by Student’s t test and comparisons between treatments and time by two-way A NOVA at 5% significance level. Results: There were no noteworthy differences between 4 or 8 weeks within each treatment group (p>0.05). When treatments were compared no significant differences between groups were found (p>0.05). Conclusions: Within the limits of this study, it can be concluded that 1% hyaluronan gel alone or its association with a carrier does not improve bone healing.

Dieta hiperlipídica e sua influência na evolução da doença periodontal experimental em ratos: resultados preliminares / Hiperlipidic diet and its influence on the evolution of experimental periodontal disease in rats: preliminary results

O presente estudou avaliou, histometricamente, a influência da dieta hiperlipídica sobre a evolução da doença periodontal experimental em ratos. Foram utilizados 32 ratos que foram aleatoriamente divididos em dois grupos: grupos 1 (ração para animais de laboratório) e grupo 2 (tacão hiperlipídica). Uma ligadura de fio de algodão foi colocada ao redor do primeiro molar inferior esquerdo e o dente contra-lateral serviu como controle. Os animais foram sacrificados nos intervalos de 7, 14, 21 e 28 dias após a colocação da ligadura para avaliarmos a doença periodontal experimental. Análise histométrica foi realizada para quantificar a perda óssea na região da bifurcação. Os dados foram analisados com os testes ANOVA e de Tukey ao nível de significância de 5%. Os animais não apresentaram alteração de peso corpóreo significante em relação ao início do experimento, diferenças também não foram encontradas entre os dois grupos (p>0.,05). Os dentes com ligadura apresentaram maior área de perda óssea (APO) que os dentes controle (p<0,0001). No entanto, não foram observadas diferenças estatisticamente significantes entre a evolução da doença periodontal e entre as diferentes dietas (p>0,05). Desta maneira, dentro dos limites deste estudo, podemos concluir que o consumo de uma dieta hiperlipídica não exerce influência sobre a perda óssea resultantes da periodontite induzida em ratos.

Thyroid hormones may influence cortical bone healing around titanium implants: a histometric study in rats.

BACKGROUND: The aim of the present study was to evaluate, by histometric analysis, the influence of the thyroid hormones, triiodothyronine (T(3)) and thyroxine (T(4)), on bone healing around titanium implants inserted in rat tibiae. METHODS: Forty-two male Wistar rats were randomly assigned to the experimental groups: G1 = healthy animals (control; N = 15); G2 = hypothyroidism (N = 13); and G3 = hyperthyroidism (N = 14). Once alterations were confirmed by total serum levels of T(3) and T(4), one screw-shaped titanium implant was placed in the rat tibiae. Sixty days later, the animals were sacrificed, and undecalcified sections were obtained. Bone-to-implant contact (BIC), bone area within the limits of the implant threads, and bone density in a 500-microm-wide zone lateral to the implant were obtained separately for the cortical (zone A) and cancellous (zone B) bone regions. RESULTS: Intergroup analysis demonstrated that thyroid hormones may significantly affect cortical bone healing around titanium implants. Hyperthyroidism significantly increased the area of newly formed bone in zone A (P <0.05), whereas hypothyroidism significantly decreased the area of newly formed bone and bone density around the implant in zone A (P <0.05) compared to the healthy group. In addition, hyperthyroidism significantly increased BIC extension in zone A compared to hypothyroidism (P <0.05). CONCLUSION: Thyroid hormones may influence the healing process in the cortical bone around titanium implants placed in rats, whereas cancellous bone seems to be less sensitive to changes in T(3) and T(4) serum levels.

Obesity and periodontal disease: why suggest such relationship? An overview

Obesity is a chronic condition that has social and economic implications for public health. It can be associated with periodontal disease since the metabolic alterations observed in that condition could have some influence in immunity. The elevated levels of lipid and glucose can be associated with periodontal disease, contributing to an exacerbated host inflammatory response, alterations in neutrophil function, and with the inhibition of macrophage growth factors, reducing tissuehealing capacity. In this way, obese individuals could have higher chances of undergoing tissue destruction in the presence of periodontal infection. On the other hand, periodontitis may be involved in alterations of lipid metabolism, since gram-negative bacteria could promote a rise in cholesterol and triglyceride levels due to chronic exposure to low levels of LPS in circulating blood, leading to the production of cytokines, which could initiate the production of lipoproteins by the liver. The objective was to review the literature about obesity and periodontal disease and provide a better understanding of their relationship.