Physical and structural characterization of bis-acryl composite resin.

During the preparation of fixed prosthesis (including individual bridges and crowns) it is important to select the materials that have the best features and properties to predict a successful clinical treatment. The objective of this study was to determine if the chemical and structural characteristics could cause to increase the fracture resistance, we used four bis-acryl resins Luxatemp, Protemp, Structur and Telio. Three-points bending by Flexural test were performed in ten bars and they were carried out to compare with Anova test. In addition, the bis-acryl resins were analyzed by scanning electron microscopy, to analyze microstructure and morphology and the molecular structure were performed by Infrared Spectroscopy through Attenuated Total Reflectance. A higher flexural strength was found in Luxatemp and Structur with, no significant differences between this study groups. Regarding Protemp and Telio, these study groups showed a lower flexural strength when were compared with Luxatemp and Structur. These results corroborate SEM and ATR analysis because Luxatemp sample showed a regular size particle on the surface and chemically presents a long cross-linkage polymer chain. The presence of CO3, SiO2 and N-H groups as a fillers particle interacting with OH groups cause a higher flexural strength compared with another groups.

Presence of methanogenic archaea in necrotic root canals of patients with or without type 2 diabetes mellitus.

Theoretically, a necrotic root canal fulfils all requirements as a niche for methanogens to inhabit. However, their presence in it and its implication in apical periodontitis (AP) is controversial. Therefore, to contribute to ending the controversy, this study aimed to detect and compare methanogens' presence in two distinct niches with supposedly different microenvironments; both were necrotic root canals associated with AP but one from patients with type 2 diabetes mellitus (T2DM) while the other from non-diabetic patients. A clinical examination was performed on 65 T2DM patients and 73 non-diabetic controls. Samples from necrotic root canals were obtained, and methanogens were identified. The presence of methanogens was three times higher (27.6%) in the T2DM group than in non-diabetic patients (8.2%). In addition, methanogens' presence was associated with a higher prevalence of periapical symptoms.

Endodontic set sealer eluates promote cytokine production in human mononuclear and periodontal ligament cells.

Endodontic freshly mixed sealers display toxic effects; however, these are significantly reduced and most become relatively inert in the set state but there is no information about the possible inflammatory reaction promoted by them. Four contemporary and different formulated endodontic set sealers (MTA Fillapex, BioRoot RCS, AH Plus, and Pulp Canal Sealer) were evaluated. Human periodontal ligament cells and human peripheral blood mononuclear cells were stimulated for 3, 6, 12 and 24 h. Interleukin-6, tumour necrosis factor-alpha, interleukin-8 and interleukin-10 concentrations were measured by enzyme-linked immunosorbent assay. All endodontic set sealer eluates promoted a similar production (P ˃ 0.05) of the four cytokines. However, their concentrations decreased within a short time period to nearly undetectable concentrations after 24 h, suggesting that the studied endodontic set sealers do not possess inflammatory properties which has favoured their long-term use in clinical practice.