Comparison of push-out bond strength of fiber-reinforced composite resin posts according to cement thickness

Fitting of Different Intraradicular Composite Posts to Oval Tooth Root Canals: A Preliminary Assessment

The purpose of the present study was to perform a preliminary analysis of the fitting of different fiber-reinforced composite (GFRC) posts to tooth root canals and determine the resin cement layer thickness. The following GFRC posts were assessed: bundle posts (Rebilda GTTM, VOCO, Germany), sleeve system (SAPTM, Angelus Ind, Brazil), and accessory posts (ReforpinTM, Angelus, Brazil). Twenty-four freshly extracted mandibular single-rooted pre-molars were endodontically treated and divided into six groups, according to the type of GFRC post and resin cement (self-adhesive or conventional dual-cured). Then, specimens were cross-sectioned and inspected by optical microscopy regarding the cement layer thickness and presence of defects such as pores, voids, or fissures were assessed. Bundle and accessory posts revealed a regular distribution of resin cement with a lower number of voids than found with sleeve systems. The sleeve system posts showed poor fitting at the apical portion of the root canals. The type of resin cement did not affect the thickness of the interface, although both bundle and accessory posts allow a better distribution of resin cement and fibers. The present preliminary study reveals interesting insights on the fitting of bundle and accessory posts to root dentin and resin cement layer thickness in oval-shape root canals. The sleeve system posts showed adequate fitting only at the coronal portion of the canals.

Evaluation of bond strength in customizing fiber post using translucent resins photoactivated by different light-emitting diodes

Aims

The objective of the study was to evaluate two translucent resin composite systems for customizing light-polymerized fiber posts with light-emitting diode (LED) curing units regarding adhesion using conventional cement at 24 h and 6 months.

Settings and Design

This was an experimental in vitro study.

Methods

Forty roots were prepared and divided into four groups (n = 10): ZV-Z350 resin and LED Valo; ZR-Z350 resin and LED Radii-Cal; OV-Opallis resin and LED Valo; and OR-Opallis resin and LED Radii-Cal. The fiber post was customized and cemented with conventional resin cement and was photoactivated by two different sources.

Statistical Analysis Used

The data were subjected to two-way ANOVA and Tukey's post hoc tests (P = 0.05). The data regarding the pattern of adhesive failures were described in terms of the frequency of occurrence in each third of the postspace.

Results

Both at 24 h and 6 months, bond strength among groups was similar, regardless of the analyzed postspace 3rd (P > 0.05). Adhesive failure Type 4 was the most frequent in all thirds.

Conclusions

Customizing the fiber post with Z350 and Opallis has the same effect on bond strength and adhesive failure pattern, regardless of the LED curing units used for photopolymerization.

Bond Strength of New Fiber Post-system (Rebilda GT)

AIM: The aim of this in vitro study is to determine the push-out bond strength of bundle glass fiber post (Rebilda GT) and tapered glass fiber post (Rebilda fiber post). MATERIALS AND METHODS: Twenty freshly extracted human single rooted premolar teeth were used, all teeth were endodontically treated, after 24 h from obturation the gutta-percha removed leaving 5 mm apically to ensure clinically acceptable apical seal. Finally, all canals were flushed with 2 ml NaOcl 5.25% and 2 ml distilled water, respectively, then the canals were dried using paper points. The roots were divided randomly into two sets with ten roots for each group according to post-type. Group A: Rebilda fiber posts were used. Group B: Rebilda GT bundle fiber posts were used. The posts were inserted into the canals according to the manufacturer instructions. All specimens were stored for 72 h in an incubator. Slices of 2 mm thickness were cut from the roots at different levels (cervical, middle, and apical thirds), bond strength was determined using universal testing machine at a speed of 0.5 mm/min. RESULTS: One-way analysis of variance and Tukey HSD tests showed that the (bundle fiber) Rebilda GT fiber post had bond strength higher than that of the Rebilda fiber post in all regions. (p < 0.05), also the cervical area showed higher bond strength in both groups than the middle and the apical areas, respectively. CONCLUSIONS: The bundle glass fiber post (Rebilda GT) showed bond strength higher than the taper glass fiber (Rebilda fiber) post in all regions (apical, middle, and cervical). The cervical region showed higher bond strength than the middle and the apical thirds.

The effect of individualization of fiberglass posts using bulk-fill resin-based composites on cementation: an in vitro study

Objectives

This study evaluated the bond strength of various fiberglass post cementation techniques using different resin-based composites.

Materials and Methods

The roots from a total of 100 bovine incisors were randomly assigned to 5 treatment groups: G1, post + Scotchbond Multi-Purpose (SBMP) + RelyX ARC luting agent; G2, relined post (Filtek Z250) + SBMP + RelyX ARC; G3, individualized post (Filtek Z250) + SBMP; G4, individualized post (Filtek Bulk-Fill) + SBMP; G5, individualized post (Filtek Bulk-Fill Flow) + SBMP. The samples were subjected to the push-out (n = 10) and pull-out (n = 10) bond strength tests. Data from the push-out bond strength test were analyzed using 2-way analysis of variance (ANOVA) with the Bonferroni post hoc test, and data from the pull-out bond strength test were analyzed using 1-way ANOVA.

Results

The data for push-out bond strength presented higher values for G2 and G5, mainly in the cervical and middle thirds, and the data from the apical third showed a lower mean push-out bond strength in all groups. No significant difference was noted for pull-out bond strength among all groups. The most frequent failure modes observed were adhesive failure between dentine and resin and mixed failure.

Conclusions

Fiberglass post cementation using restorative and flowable bulk-fill composites with the individualization technique may be a promising alternative to existing methods of post cementation.

Comparison of Self-Etching Ceramic Primer and Conventional Silanization to Bond Strength in Cementation of Fiber Reinforced Composite Post

Various mechanical and chemical surface treatments have been proposed to improve the retention of fiber-reinforced composite post (FRCP), but the results are still controversial. The bond strength and durability of a self-etching ceramic primer, which was recently released as an alternative to etching and silane, are not yet known. This study aimed to compare and evaluate the push-out bond strength of different surface treatments of FRCPs after an artificial aging procedure. Four groups (n = 10) were established to evaluated FRCP surface treatments (dentin adhesive bonding; silane and adhesive bonding; hydrofluoric acid, silane and adhesive bonding; and a self-etching ceramic primer). They were bonded with dual-curing rein cement (Multilink N) and stored in distilled water at 37 °C for 30 days, then thermal cycled for 7500 cycles. After being sectioned into 1 mm thickness, each coronal and apical part was evaluated for its the push-out bond strength by a universal testing machine. Each debonded specimen was observed by an optical microscope and divided according to the failure modes. The results showed that silane treatment significantly improved push-out bond strength, but the self-etching ceramic primer did not do so. Additional hydrofluoric acid treatment or the adhesive bonding agent alone did not significantly improve the retention of FRCPs. Cohesive failure of the luting material was found most frequently in all groups.

Effect of cement type and thickness on push-out bond strength of fiber posts

Background. This study investigated the effect of the thickness of two resin cements on push-out bond strength of fiber posts to root dentin.

Methods. Sixty decoronated single-rooted teeth were endodontically treated. The specimens were then randomly allocated to two groups (n=30); group 1: drill size 90 w, matching the size of fiber posts used; group 2: drill size 110, larger than the posts. The specimens in each group were divided into 2 subgroups (n=15); subgroup SE, in which the posts were cemented with self-etch Panavia F2.0 and subgroup SA, in which self-adhesive Panavia cement was used. After 72 hours, 2 slices with 1 mm of thickness were prepared from the mid-root of each specimen. Push-out bond strength test was performed in a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and t-test.

Results. The mean bond strengths of the posts cemented in matched-size spaces for SE and SA groups were 4.02±1.6 and 4.12±2.3 MPa, respectively. For posts cemented in oversized spaces, the values were 4.9±2.3 and 2.8±1.3 MPa, respectively. In matched-size spaces, there was no significant difference between the two groups.

Conclusion. The results of this study suggested that increasing the cement thickness would reduce the bond strength of fiber posts to root dentin when self-adhesive cements are used; however, self-etch adhesives were not affected.

Evaluation of the effect of chlorhexidine and sodium hypochlorite in adhesive cementation of fiber posts - in vitro study

Abstract Introduction The attachment of fiberglass posts is achieved through an adhesive process. Failures in adhesion may occur due to the hydrolytic degradation of the adhesives, or to the degradation of the collagen fibres of the hybrid layer by intrinsic enzymes. Objective To evaluate the effect of chlorhexidine and sodium hypochlorite treatment on bond strength to dentin. Material and method Thirty bovine roots were randomly distributed into 3 groups (n=10): a) Control, b) 2% Chlorhexidine, and c) 5% Sodium Hypochlorite. Next, RelyX® ARC resin cement was used to cement the post. Each specimen resulted in samples from the three root thirds that were submitted to the pushout test (MPa) at 24 hours and 12 months. Bond strength values were analysed using the Kolmogorov-Smirnov, 3-way ANOVA and Tukey tests. The fracture mode of the pin was also analysed using stereomicroscopy. Result There were no significant differences between treatments at the immediate time (p=0.0644) or in the interaction of factors (p=0.1935). After one year, the experimental groups showed no significant differences in bond strength in relation to the control group, with the exception of the cervical third of the chlorohexidine group in which there was a significant loss of adhesion. As for the fracture mode, there was a predominance of the mixed type in all groups and thirds. Conclusion The use of chlorhexidine or hypochlorite provides neither benefits nor losses in the adhesive bond strength of fiberglass posts. However, there is an influence of the root thirds, with the worst bond strength in the apical third.

Effect of Anatomical Customization of the Fiber Post on the Bond Strength of a Self-Adhesive Resin Cement

AIM

The aim of the study was to evaluate, by means of the push-out test, the effect of the anatomical customization of the fiber post on the bond strength of a self-adhesive resin cement.

METHODS

Twelve endodontically treated, human, upper central incisors were randomly divided into two groups (n = 6): control (glass fiber posts cemented with Relyx® U200) and customized (glass fiber posts anatomically customized with translucent composite resin cemented with Relyx U200). The roots were sectioned into three slices, cervical, middle, and apical, and photographed with a digital camera attached to a stereomicroscopic loupe. The images were analyzed by software, for evaluation of the cement line. The slices were subsequently submitted to the push-out test until the post had completely extruded, and the fracture mode was analyzed with a stereomicroscopic loupe.

RESULTS

The results showed significant differences between the groups in the different root thirds in relation to the area occupied by air bubbles (p < 0.05). Bond strength, when all the thirds are considered, was 8.77 ± 4.89 MPa for the control group and 16.96 ± 4.85 MPa for the customized group.

CONCLUSION

The customized group showed greater bond resistance than the control group and a more uniform cement layer.