Research and Education
Retentive strength of fiber-reinforced composite posts with composite resin cores: Effect of remaining coronal structure and root canal dentin conditioning protocols

https://doi.org/10.1016/j.prosdent.2015.06.015Get rights and content

Abstract

Statement of problem

The prognosis of a fixed dental prosthesis cemented to endodontically treated teeth is primarily determined by the presence of a ferrule on the tooth. Adhesion of the post in the root canal, conditioning methods for the canal and the amount of coronal structure could also be decisive on survival of reconstructions cemented on endodontically treated teeth.

Purpose

The purpose of this in vitro study was to test the effect of remaining coronal structure on the retention of airborne-particle abraded fiber-reinforced composite resin posts built up with composite resin cores after the treatment of root canal dentin with different conditioning protocols.

Material and methods

One hundred and fifty extracted human teeth with single root canal space were endodontically treated and divided into 3 groups as follows: group CEJ: the teeth were sectioned at the level of cementoenamel junction (CEJ); group CEJ1: the teeth were sectioned 1 mm above the CEJ; group CEJ2: the teeth were sectioned 2 mm above the CEJ. Each group was further divided into 5 subgroups (n=10 per group) according to the root canal treatments as follows: group C: no conditioning (control); group PH: conditioning with 37% phosphoric acid gel for 15 seconds; group E: conditioning with 17% ethylenediaminetetraacetic acid (EDTA) for 60 seconds; group CHX: conditioning with 2% chlorhexidine (CHX) for 60 seconds; group Q: conditioning with combination of 2% CHX with 17% EDTA and a surfactant solution for 60 seconds. Glass fiber-reinforced composite resin posts were airborne-particle abraded and luted to the root canal dentin with a self-adhesive resin cement (RelyX Unicem). The retentive force was tested by applying a tensile load parallel to the long axis of these posts at a crosshead speed of 2 mm/min. Two-way ANOVA and the Tukey HSD post hoc test were used to analyze the data.

Results

The highest retention (N) was obtained with the CHX-EDTA conditioned group (374.7 ±29.8) followed by 17% EDTA (367.9 ±33.3) conditioning when 2 mm remaining coronal structure was available. Conditioning with the CHX-EDTA showed comparable retention values to 17% EDTA conditioned groups when 0 or 1 mm coronal structure was present that differed significantly compared to 37% PH and 2% CHX conditioning (P<.05).

Conclusions

Conditioning root canal either with CHX-EDTA or 17% EDTA delivered superior retention values for fiber-reinforced composite resin posts with composite resin cores that were luted with self-adhesive resin cement to endodontically treated teeth with 2 mm remaining coronal structure.

Section snippets

Material and Methods

After gaining informed consent from patients with periodontitis and teeth with grade III mobility, 150 extracted human maxillary anterior teeth were obtained for this study. Approval to use human teeth was obtained from the Research Ethics Committee at the Faculty of Dentistry, Mansoura University, Egypt. Power analysis was performed before conducting this study (SAS/STAT v12.1 software; SAS Institute) to determine the number of specimens required in each experimental group to determine

Results

The mean values and standard deviations of retentive forces (N) obtained for the fiber-reinforced posts bonded to differently conditioned root canal dentin substrates and the 3 remaining coronal structures are presented in Table 1 and Figure 3. The highest mean retentive force (N) value was recorded with the remaining coronal structure of 2 mm in group Q (374.7 ±29.8 N), while the lowest mean value was obtained from group C (205 ±11.7 N). Root canal surface conditioning significantly affected

Discussion

The results of this in vitro study support the rejection of the null hypothesis that root canal dentin conditioning would not affect the retention of fiber-reinforced posts with composite resin cores luted to different amounts of remaining coronal structure with self-etch adhesive luting resin cement. The results of this study showed significant influence of the amount of remaining coronal structure and root canal dentin surface conditioning on the retention of the fiber-reinforced composite

Conclusions

From this in vitro study, the following could be concluded:

  • 1.

    Luting fiber-reinforced composite resin posts with self-adhesive resin cement after root canal dentin conditioning with either a combination of 2% CHX with 17% EDTA and a surfactant solution or 17% EDTA produced significantly higher retention values compared with those with dentin conditioning with 37% phosphoric acid.

  • 2.

    The preservation of the remaining coronal structure of endodontically treated teeth increased the retentive strength of

Acknowledgments

The authors thank Dr Walid El-Zordek for help in the preparation of this manuscript.

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