1. M ETHODS *aline.gabriel@forp.usp.br A BSTRACT Objective: To compare the push-out bond strength of an epoxy resin-based sealer (AH Plus) and gutta-percha to human and bovine intraradicular dentin, aiming to verify the suitability of bovine teeth as a substitute for human substrate in push-out studies. Methods: Ten roots of human maxillary incisors and ten roots of bovine incisors were prepared until #80 k-files and #180 k-files for human and bovine roots respectively, using Crown-down technique. Irrigation was done with 1% NaOCl at each change of instrument and a final rinse with 17% EDTA. The specimens were filled with AH plus sealer and gutta-percha cones. Roots were sectioned to obtain 1-mm-thick slices from cervical, middle and apical canal thirds. After 24 h, slices were submitted to push-out test in universal testing machine, using specific points for each canal third of both substrates. Data (MPa) were submitted to two-way ANOVA, considering substrate and root canal third as independent variables. Post-hoc analysis was done using Tukey test (α=0.05). Failure types were recorded. Results: Significant differences were found for the bond strength values between bovine- (0.35±0.08) and human-root dentin (0.93±0.62) (p 0.05) as well as for the interaction between factors (p>0.05). Adhesive failures predominated in both groups. Conclusion: Although the bond strength of human teeth was superior than bovine teeth, both substrates have the same performance in all the root canal thirds. This indicates that bovine teeth might be a substitute to human counterparts in push-out strength tests. R ESULTS The aim of this study was to compare the push-out bond strength of an epoxy resin-based sealer (AH Plus) and gutta-percha to human and bovine intraradicular dentin, aiming to verify the suitability of bovine teeth as a substitute for human substrate in push-out studies. C ONCLUSION Cervical Cervical Middle Middle Apical Apical HUMAN HUMAN 0.64 ± 0.56 A a 0.80 ± 0.34 A b 1.07 ± 0.33 A c BOVINE BOVINE 0.16 ± 0.14 B a 0.32 ± 0.14 B b 0.7 ± 0.34 B c R R EFERENCES Although the bond strength of human teeth was superior than bovine teeth, both substrates have the same performance in all the root canal thirds. This indicates that bovine teeth might be a substitute to human counterparts in push-out strength tests. Bruniera J. F., Flores A. C. R., Messias D. C. F.; Silva-Sousa Y. T. C., Souza-Gabriel A. E.* University of Ribeirão Preto, Dental Course, Ribeirão Preto, SP, Brazil University of São Paulo, School of Dentistry of Ribeirão Preto, Ribeirão Preto, SP, Brazil Bruniera J. F., Flores A. C. R., Messias D. C. F.; Silva-Sousa Y. T. C., Souza-Gabriel A. E.* University of Ribeirão Preto, Dental Course, Ribeirão Preto, SP, Brazil University of São Paulo, School of Dentistry of Ribeirão Preto, Ribeirão Preto, SP, Brazil PUSH-OUT STRENGTH OF RESIN-BASED SEALER TO HUMAN AND BOVINE DENTIN PUSH-OUT STRENGTH OF RESIN-BASED SEALER TO HUMAN AND BOVINE DENTIN 1.Galhano, G.; Melo, R. M.; Valandro, L. F.; Bottino, M. A. Comparison of resin push-out strength to root dentin of bovine- and human- teeth. J. Dent. Res. v. 20, n. 3, p. 337-339, 2009. 2.Rüttermann, S.; Braun, A.; Janda, R. Shear bond strength and fracture analysis of human vs. bovine teeth. PLoS One. v. 8, n. 3, e59181, 2013. 3.Saleh, F.; Taymour, N. Validity of using bovine teeth as a substitute for human counterparts in adhesive tests. East Mediterr Health J. v. 9, n. 1, p. 201-7, 2003. Table1. Mean and standard deviation of the experimental conditions Human teeth n=10 Significant differences were found for the bond strength between bovine - (0.35±0.08) and human root dentin (0.93±0.62) (p<0.05). No significant differences were found for root canal thirds, as well as for the interaction between factors (p>0.05). Adhesive failures predominated in both groups. Data (MPa) were submitted to two-way ANOVA and post-hoc Tukey test (α=0.05) P URPOSE Financial support: PiBiC /CNPq – Brazil Abstract ID: 184537 Bovine teeth n=10 A B A B Figure 1. Ten human maxillary incisors and ten bovine incisors were sectioned and roots were standardized (16 mm). Figure 2. A) Working length was established 1 mm from the root apex. B) Cervical third preparation using #25 and #10 files. Figure 3. Roots were prepared until #80 k- files and #180 k-files for human and bovine roots respectively, using Crown-down technique. Figure 7. Sectioning machine (Isomet, Bueher) used to obtain dentin slices (± 1,0 mm). Figure 4. AH Plus sealer used to fill root canals. Figure 5. Selection of guta percha master cone Figure 6. Root canal obturation using lateral condensation technique Figure 9. A - Universal testing machine used in push-out test, B - Slice positioned in testing machine, C - Tips used for push-out test - human cervical third: 1.5mm tip; human middle third: 1 mm; human apical third: 0.5mm; bovine cervical third: 2.5 mm; bovine middle third: 1.5 mm and bovine apical third: 1mm. Figure 8. Slices of the 3 root canal thids. Different capital letters indicated difference within columns Different lower case letters indicated difference within lines