Effect of ultrasonic and sonic activation of root canal sealers on the push-out bond strength and interfacial adaptation to root canal dentine

Abstract

Aim

To evaluate the effect of ultrasonic and sonic activation of two root canal sealers on interfacial adaptation and push-out bond strength (BS) to root canal dentine.

Methodology

The root canals of seventy-eight roots of maxillary canines was prepared with Ni-Ti rotary instruments under irrigation with 2.5% NaOCl and 17% EDTA. Canals were filled by lateral condensation of gutta-percha and AH Plus (n=39) or MTA Fillapex (n=39). Three subgroups (n=13) were formed according to sealer activation: no activation (NA), sonic activation (SA, 20 s) and ultrasonic activation (US, 20 s). In 3 specimens of each subgroup, 0.1% Rhodamine B was added to the sealer. Three 1-mm-thick slices were obtained from each root third. The first and second were used for push-out BS test and the third for a qualitative analysis of interfacial adaptation (gaps) and voids by confocal laser scanning microscopy (CLSM). Intratubular penetration of Rhodamine B-labelled sealer was also assessed by CLSM. Data were analysed by two-way ANOVA and Tukey's test (α=0.05).

Results

AH Plus (2.58±1.21) had higher push-out BS than MTA Fillapex (1.45±0.71) (P = 0.000). UA (2.64±1.44) had higher BS (P = 0.000) than NA (1.58±0.73) and SA (1.83±0.85), which did not differ significantly from each other (P = 0.3303). The coronal third had higher BS (2.48±1.49) the middle (2.08±0.94) (P = 0.0003) and apical (1.48 ± 0.58) (P = 0.00) thirds. For both sealers, UA was associated with a more homogeneous filling material with better interfacial adaptation and greater quantity, density and length of tags in dentinal tubules. When UA was used, the tags had similar quantity, density and length to those formed without activation, but interfacial gaps and voids were observed.

Conclusion

Ultrasonic activation was associated with higher bond strength values, deeper intratubular penetration and greater interfacial adaptation to root dentine than sonic activation and no activation techniques, AH Plus had higher bond strength values than MTA Fillapex irrespective of the type of activation.

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