Abstract
Objectives To evaluate the influence of two curing techniques on the degree of conversion (DC) of resin cements and on bond strength (BS) of fiber posts in different regions of root dentin.Material and Methods Twenty single-rooted premolars were endodontically treated, and the post spaces were prepared. The roots were randomly divided into two groups (n=10), according to the activation mode of the resin cement RelyX™ U200 (3M ESPE Saint Paul, MN, USA): conventional (continuous activation mode) and soft-start activation mode (Ramp). The posts (WhitePost DC/FGM) were cemented according to the manufacturer’s recommendations and, after one week, the roots were cross-sectioned into six discs each of 1-mm thickness, and the cervical, medium, and apical thirds of the root canals were identified. The DC was evaluated under micro-Raman spectroscopy and the BS was evaluated by the push-out test. The data were analyzed by two-way ANOVA and Tukey’s test (α=0.05).Results Neither the activation mode nor the root regions affected the DC of the resin cement. Higher BS was achieved in the soft-start group (p=0.036); lower BS was observed in the apical third compared to the other root regions (p<0.001). Irrespective of the activation mode and root region, the mixed failure mode was the most prevalent.Conclusion The BS of fiber posts to root canals can be improved by soft-started polymerization. The DC was not affected by the curing mode.
Highlights
Treated teeth usually demonstrate an extensive loss of dental structure and require the XVHRILQWUDUDGLFXODUUHWDLQHUVDQG¿OOLQJFRUHVWRKROG WKH¿QDOUHVWRUDWLRQ29
Despite recent studies that have evaluated the VKULQNDJH VWUHVV DQG DFWLYDWLRQ SURWRFRO DVVRFLDWHG ZLWK ¿EHU SRVW FHPHQWDWLRQ6,23, the literature is still limited regarding the use of different curing techniques and their effects on the aforementioned properties
In the present investigation we opted to use the push out bond strength test to evaluate the strength of WKHERQGLQJEHWZHHQWKH¿EHUSRVWVWRWKHURRWFDQDO
Summary
Treated teeth usually demonstrate an extensive loss of dental structure and require the XVHRILQWUDUDGLFXODUUHWDLQHUVDQG¿OOLQJFRUHVWRKROG WKH¿QDOUHVWRUDWLRQ29. In this context, the cementation RI¿EHUSRVWVLQHQGRGRQWLFDOO\WUHDWHGFDQDOVUHVXOWVLQ restorations that resemble the natural dental structure because the modulus of elasticity of the adhesive PDWHULDOVDQG¿EHUSRVWVDUHVLPLODUWRWKDWRIGHQWLQ14. Different areas of the same root canal do not respond to acid etching, and the ability of adhesion to root dentin may be different at different depths in the same root canal[11]. Higher bond strength values at the cervical third are generally expected due to the ease of conditioning, and polymerization of the cements in this region[9].
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