In vitro bond strength of an epoxy resin-based root canal sealer to root dentin irradiated with high-power lasers and adhesive interface analyses.

The aim of this study was to evaluate in vitro the influence of high-power lasers (Nd:YAG and diode 980 nm) associated with mineral coal as fotopotencializer on bond strength of an epoxy resin-based root canal sealer to root dentin, using the pushout test, and on the dentin/filling material interface, using confocal laser microscopy. For this purposes, 50 canines were instrumented with Mtwo rotary system up to #50.04 instrument and randomly assigned to five groups (n = 10): group I-control EDTAC; group II-EDTAC and Nd:YAG laser; group III-EDTAC and diode laser 980 nm; group IV-EDTAC, Nd:YAG laser and mineral coal 5 g/100 mL; and group V-EDTAC, diode laser 980 nm and mineral coal 5 g/100 mL. All data were analyzed by ANOVA (at 5% significance level) following the Kruskal-Wallis, Dunn and Tukey tests. The group I increased more bond strength of the sealer to root dentin that treated with only EDTAC 17% (17.21 ± 21.75 MPa), similar to the group II (12.21 ± 18.20 MPa) and group IV (14.92 ± 28.06 MPa), both treated with Nd:YAG laser, with the exception of group IV, which was added to mineral coal. The group V (8.75 ± 13.42 MPa) had similar results to the groups II and IV, but the same similarity were found when compared with group III (7.11 + 11.28 MPa), with lower results. Regarding the root thirds, the apical third (23.27 ± 29.21 MPa) presented a statistically higher value on bond strength than the cervical third (5.92 ± 5.33 MPa) and middle third (6.93 ± 7, 11 MPa) (p > 0.05). Group II (86.27 µm) showed the highest tags penetration values, with a statistically difference to the group III (51.57 µm), IV (36.77 µm) and V (32.37 µm) (p < 0.05). Group I (71.63 µm) was statistically similar to groups II and III (p > 0.05). Group IV had the lowest values and was statistically similarity to groups III and V (p > 0.05). It was concluded that the treatment with Nd:YAG laser provides better results than the diode 980 nm laser, except when was added mineral coal. The control and diode 980 nm laser groups presented less adhesive failures and more mists failures than the other groups. Both lasers did not interfere negatively compared to the control group.

Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts.

The present study evaluated, in vitro, the influence of an eugenol-based endodontic sealer (EndoFill) on the adhesion of intra-radicular posts cemented with a resin-based cement (Enforce) ou a zinc phosphate cement. Twenty-four single-rooted maxillary canines were divided into 2 groups (n=12) and obturated with either gutta-percha points plus EndoFill or gutta-percha points alone (no cement). In each group, half of intracanal posts (n=6) were cemented with Enforce resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test in an Instron machine and tensile force was applied at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal was recorded (N) and means were submitted to statistical analysis by Kruskal-Wallis test (p<0.01). Posts cemented with zinc phosphate cement were significantly more retentive (353.4 N) than those cemented with Enforce (134.9 N) (p<0.01). Regarding the influence of the eugenol-based cement (EndoFill) on post retention, there was statistically significant difference (p<0.01) only between the groups cemented with Enforce, i.e., in the canals filled with EndoFill + guta-percha there was lower bond strength than in the canals filled with gutta-percha points alone (101.5 and 168.2 N, respectively). In conclusion, the zinc-phosphate-based cement showed greater post retention than the resin-based cement. The findings of this study suggest that the eugenol-containing sealer interfered with the adhesive properties of the resin-based cement.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis.

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and gutta-percha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (+/-SD) in MPa were: G1 (8.8+/-1.13), G2 (5.9+/-1.05) and G3 (3.8+/-0.55). Statistical analysis by ANOVA and Student's t-test (alpha=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to gutta-percha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skillful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and gutta-percha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (a=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to gutta-percha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Avaliação da adesividade à dentina do cimento AH Plus e Epiphany associados aos cones de resilon e guta-percha / Bond Strengh of endodontic sealers associated to resin and gutta-percha point

Este estudo avaliou in vitro a adesividade dos cimentos endodônticos associados aos cones deresilon e guta-percha, pelo método push-out. Foram utilizados 40 caninos superiores humanos, que tiveramas raízes seccionadas transversalmente na junção amelo-cementária e, novamente a 8 mm desta emdireção apical. Os cilindros de raiz obtidos foram incluídos em anéis de alumínio e preenchidos com resinaacrílica. Os espécimes tiveram o diâmetro do canal aumentado com broca troncônica, foram tratados comEDTA a 17% por 5 minutos, irrigados com água destilada pelo mesmo tempo e secos com cones de papelabsorvente. Os espécimes foram então distribuídos aleatoriamente em 4 grupos (n=10) de acordo como material de preenchimento do canal: GI AH Plus/guta-percha (controle); GII AH Plus/Resilon; GIIIEpiphany/Resilon; GIVEpiphany/guta-percha. Decorridos três vezes o tempo de endurecimento decada cimento, os corpos-de-prova foram submetidos ao teste de push-out. O teste de Tukey revelou queas maiores médias foram obtidas pelo GIV (0,30 ± 0,051 KN), que foi estatisticamente diferente dos demaisgrupos (p<0,01). Os valores intermediários foram obtidos pelo GI (0,20 ± 0,072 KN) e GIII (0,16 ± 0,024KN), que foram estatisticamente semelhantes entre si (p>0,01), e os menores valores foram verificadosno GII (0,05 ± 0,03 KN). Concluiu-se que a associação do cimento aos cones de guta-percha favoreceu aadesividade às paredes do canal radicular.

This study evaluated in vitro the bond strength of endodontic sealers associated to Resilon andgutta-percha points, using the push-out test. A total of 40 maxillary human canines were sectioned at thecementoenamel junction and at 8 mm from this point in apical direction. The root cylinders obtained wereincluded in aluminum molds and filled with acrylic resin. The specimens had the diameter of the canalincreased with trunk-conical drill, and then were treated with 17% EDTA for 5 min, irrigated with distilledwater for the same time and dried with paper points. The specimens were randomly distributed into 4 groups(n=10) and filled as follows: GI AH Plus/gutta-percha (control); GII AH Plus/Resilon; GIII Epiphany/Resilon; GIV Epiphany/gutta-percha. After the setting time of sealer, the specimens were submitted to thepush-out test. The Tukey´s test revealed that the highest average was obtained by GIV (0.30 ± 0.051 KN),which was statistically different from the other groups (p<0.01). The intermediary values were obtained by GI(0.20 ± 0.072 KN) and GIII (0.16 ± 0.024 KN) that were statistically similar among themselves (p>0.01), andthe lowest mean values were verified in GII (0.05 ± 0.03 KN). It may be concluded that the association of theEpiphany sealer to gutta-percha points favored the bond strength to the root canal walls.

Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts

No presente estudo avaliou-se, in vitro, a influência do cimento endodôntico à base de óxido de zinco e eugenol (EndoFill) na adesão de pinos intra-radiculares cimentados com cimento resinoso (Enforce) ou cimento fosfato de zinco. Vinte e quatro caninos superiores uniradiculares foram distribuídos em dois grupos e obturados com cimento a base de oxido de zinco e eugenol + cones de guta-percha ou somente cones de guta-percha (sem cimento). Em metade dos espécimes em cada grupo (n=6), os pinos intra-radiculares foram cimentados com cimento resinoso Enforce e na outra metade com cimento de fosfato de zinco. Os espécimes foram submetidos a ensaios de resistência à tração numa máquina Instron 4444, sendo os valores de força máxima necessária ao desprendimento dos retentores registrados e submetidos à análise estatística pelo teste de Kruskal-Wallis (p<0,01). Os pinos cimentos com cimento fosfato de zinco apresentaram valor médio de resistência à tração superior (353,4 N) ao dos pinos cimentados com Enforce (134,9 N). Em relação à influência do cimento à base de eugenol na retenção dos pinos intra-radiculares, houve diferença significante (p<0,01) somente entre os grupos cimentados com Enforce, sendo que nos canais obturados com EndoFill + guta-percha houve menor resistência à tração que nos canais obturados apenas com guta-percha (respectivamente 101,5 e 168,2 N). Conclui-se que o cimento à base de fosfato de zinco apresentou maior retenção que o cimento resinoso Enforce e que o cimento obturador contendo eugenol (EndoFill) somente afetou as propriedades adesivas do cimento resinoso.