The purpose of this study was to compare the regional bond strengths of C&B Metabond resin to root canal dentin, with or without treatment using a eugenol-containing endodontic sealer liquid. Eighteen extracted human canines were decoronated at the cementoenamel junction with a slow speed saw. The apical third of the root was removed leaving the cervical and middle dentin. The canal space was then enlarged with files, Gates-Glidden burs, and parapost drills. The teeth were ground on either the mesial or distal sides, permitting direct access to the entire canal. The cervical or middle third dentin was treated with Kerr Root Canal Sealer liquid, alternating between the middle and cervical thirds. Each tooth served as its own control. The adhesive resin was then luted directly to the prepared canal. Specimens, 1 x 1 x 8 mm, were prepared and mounted to a Vitrodyne testing machine enabling microtensile bond strengths to be measured. Data were analyzed using a two-way ANOVA and the least squares means test. The mean microtensile bond strengths for the cervical and middle third dentin treated with eugenol were 13.6 +/- 6.1 MPa (n = 33) and 14.8 +/- 3.9 MPa (n = 29), respectively. Without the eugenol, the mean bond strengths were 18.1 +/- 6.0 MPa (n = 31) and 17.3 +/- 4.6 MPa (n = 31) for the cervical and middle sections. The specimens treated with the eugenol liquid had significantly lower bond strengths than those without eugenol (p < 0.05) only in the cervical third. The region of the tooth tested had no effect on bond strength. That is, bond strength of the cervical third was not significantly different from bond strength on the middle third in either of the two groups (with or without eugenol) tested.
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