Evaluation of Stress Distribution in Endodontically Weakened Teeth Restored with Different Crown Materials: 3D-FEA Analysis

<div><p>Abstract This study evaluated the stress distribution in endodontically treated teeth, weakened (W) or not weakened (NW), restored with different materials of prosthetic crown using 3D-FEA. Models of a maxillary canine were constructed based on micro-CT images and divided into the groups: G1 (control) - sound tooth; G2 to G7 - endodontically treated teeth restored with glass fiber post (GFP); which G2 to G4 simulated NW root and G5 to G7 simulated W root. For crown material the teeth were restored with: G2 and G5: metallic coping and ceramic veneering, G3 and G6: zirconia coping and ceramic veneering, G4 and G7: alumina coping and ceramic veneering. Load of 180 N was applied at the incisal third of lingual surface at 45º. Models were supported by the periodontal ligament (x=y=z=0). The von Mises stress (VMS) values were calculated. The W teeth presented higher VMS at coping when compared to NW teeth and group G1 showed lower VMS value. For crown material, for both W or NW teeth, increasing VMS was found at metallic, zirconia and alumina coping, respectively. Metallic coping showed a better performance despite its unfavorable esthetics, suggesting as an appropriate material for prosthetic restoration of endodontically treated teeth.</p></div

Cytotoxicity Evaluation of Root Canal Sealers Using an In Vitro Experimental Model with Roots

<div><p>Abstract The aim of the present study was to evaluate the cytotoxicity of root canal sealers under conditions closely resembling a clinical reality. A primary human fibroblast cell line was seeded in 24-well acrylic plates with Dulbecco’s modified Eagle’s medium supplemented with 10% serum fetal bovine (SFB) and incubated for 24 h. Root canals from premolars were filled and individually attached to nylon devices to be stabilized in the wells with the already seeded cells. Specimens were divided into groups as follows: Control: gutta-percha cones (GPC); AH Plus+GPC; Sealapex+GPC; MTA Fillapex+GPC and Endofill+GPC. After 24 and 48 h, cell viability and morphology were evaluated by MTT assay and scanning electron microscopy (SEM), respectively. Statistical analysis was performed by Mann-Whitney test, complemented by Kruskal Wallis test (p<0.05). Only Endofill presented cytotoxicity after 24 h. MTA Fillapex and Endofill reduced the production of succinic desidrogenase after 48 h. AH Plus was non-toxic at any time point. SEM showed that the AH Plus and MTA Fillapex groups presented fibroblasts with morphology close to the control group, while the Endofill group presented few cells with thin extensions cells. The present study showed that good results were present in AH Plus and Sealapex, but not the Endofill group after 48 h. The method used enabled evaluation of the cytotoxicity of the studied sealers that diffused through the root apex.</p></div