Evaluation of Different Techniques and Materials for Filling in 3-dimensional Printed Teeth Replicas with Perforating Internal Resorption by Means of Micro-Computed Tomography.

INTRODUCTION: The aim of this study was to evaluate the filling ability of 2 obturation techniques in 3-dimensional (3D) printed teeth with perforating internal resorption (PIR). METHODS: A maxillary central incisor was instrumented and scanned by micro-computed tomographic (micro-CT) imaging. The 3D model was exported in the stereolithographic format and, with the aid of OrtogOnBlender software (Cícero Moraes, Sinop, SP, Brazil), a PIR in the middle third of the root canal was designed. Thirty-two replicas were printed in surgical resin and distributed into 4 groups (n = 8) according to the obturation technique and the material used: 2 groups used the hybrid technique, 1 with Bio-C Sealer (BCS; Angelus, Londrina, PR, Brazil)/gutta-percha (GP; VDW GmbH, Munich, Germany) + Bio-C Repair (BCR; Angelus, Londrina, PR, Brazil) and the other with BioRoot (BR; Septodont, Saint Maur des Fosses, France)/gutta-percha (GP) + Biodentine (BD; Septodont, Saint Maur des Fosses, France), and 2 groups used the incremental technique, 1 with BCR and the other with BD. Postobturation micro-CT imaging was performed to measure the percentage volume of voids and laser confocal microscopy to measure the surface roughness (µm) of the repair cements. Data were compared using analysis of variance and Kruskal-Wallis tests. RESULTS: Regarding the filling volume in the apical third, the BCS/GP + BCR (89.70 ± 5.15), BR/GP + BD (87.70 ± 8.43), and BCR (84.20 ± 9.00) groups showed the highest percentages compared with the BD group (69.70 ± 6.88) (P < .05). In the area of internal resorption, the BCS/GP + BCR (96.00 ± 2.64) and BCR (95.30 ± 2.93) groups showed the highest percentages compared with the BR/GP + BD group (91.50 ± 1.35) (P < .05). The BD group showed intermediate values that were sometimes similar to the BCS/GP + BCR and BCR groups and similar to the BR/GP + BD group (P > .05). Regarding the quality of the filling in the perforation area, the BCR group showed better results compared with the BD group (P < .001). Regarding roughness, the BCR group (1.66 ± 0.65) showed lower surface roughness compared with the BD group (2.51 ± 0.89) (P < .05). CONCLUSIONS: The capacity and quality of the filling in teeth with PIR were superior with the incremental technique with BCR and the hybrid technique with BCS/GP + BCR.

Can Carbodiimide (EDC) and Chitosan Cross-linking Agents Effect the Longevity of Fiberglass Posts Luted with Different Types of Composite Cements to Root Dentin?

PURPOSE: To evaluate the effect of carbodiimide (EDC) and chitosan (CHI) on the enzymatic activity (EA) and bond strength (BS) of different composite cements to root dentin. MATERIALS AND METHODS: Ninety (90) maxillary canines were sectioned, standardizing the length of the roots. The roots were endodontically treated, prepared, divided into 3 groups according to dentin treatment (distilled water [DW], CHI 0.2 wt%, or EDC 0.5M), and further subdivided into 3 subgroups according to composite cement (RelyX ARC [3M Oral Care], Panavia F 2.0 [Kuraray Noritaki], or RelyX U200 [3M Oral Care]). Of the slices obtained by sectioning, the most cervical of each third were subjected to a push-out test and the most apical were subjected to in-situ zymography. Half of the slices were analyzed immediately, and the other half after 6 months. The results were analyzed with ANOVA or the chi-squared test. RESULTS: RelyX ARC showed higher BS associated with CHI, while RelyX U200 showed higher BS associated with EDC (p = 0.044). For Panavia F 2.0, the treatment did not influence BS (p > 0.05). For the cervical and middle thirds, no differences were observed between the cements, while the apical third revealed higher BS for RelyX U200 (p < 0.001). The highest percentage of adhesive-to-dentin failures was observed for Panavia F 2.0. EDC showed the lowest percentage of adhesive-to-dentin failures. According to zymographic analysis, DW and CHI showed greater fluorescence for RelyX ARC, while EDC exhibited the lowest fluorescence of all cements (p > 0.05). CONCLUSION: The different mechanisms of action of solutions for pre-treatment of intraradicular dentin yielded different results depending on the adhesive used. EDC resulted in higher bond strength and higher enzyme inhibition for RelyX U200, while the treatment with chitosan resulted in higher bond strength and lower enzymatic activity for RelyX ARC. Although EDC and chitosan treatments did not influence the bond strength for Panavia F 2.0, both resulted in higher enzyme inhibition for this composite cement.