Two-year clinical performance of dual- and light-cure bulk-fill resin composites in Class ӀӀ restorations: a randomized clinical trial

OBJECTIVE

This study aimed to compare the clinical performance of dual- and light-cure bulk-fill resin composites (BFRCs) in Class ӀӀ restorations after 2 years.

MATERIALS AND METHODS

A double-blinded, prospective, randomized clinical trial (RCT) was conducted following the CONSORT (Consolidated Standard of Reporting Trials) guidelines. Forty patients were enrolled in the study. Each patient received three compound Class ӀӀ restorations. One dual-cure (Fill-Up; Coltene Waledent AG) and two light-cure (QuiXfil; Dentsply, and Tetric N-Ceram Bulk Fill; Ivoclar Vivadent) BFRCs were used for 120 Class ӀӀ restorations. A universal adhesive (ONE COAT 7 UNIVERSAL; Coltene Waledent AG) was used with all restorations. Restorations were clinically evaluated after 1 week (baseline), 6 months, 12 months, 18 months, and finally after 24 months using the FDI World Dental Federation (FDI) criteria. The Kruskal-Wallis test was used for comparison between BFRCs groups at baseline and at each recall period, and the Wilcoxon signed-rank test was used for comparing different follow-up times of each BFRC to baseline. The level of significance was set at p < 0.05.

RESULTS

All BFRCs restorations showed only minor changes and revealed no statistically significant differences between their clinical performance for all evaluated parameters at all recall periods; also, there was no statistically significant difference between all recall periods and baseline for all evaluated parameters.

CONCLUSION

The two-year clinical performance of dual-cure BFRC was comparable to light-cure BFRCs in Class ӀӀ restorations.

CLINICAL RELEVANCE

Dual- and light-cure BFRCs showed excellent clinical performance in Class ӀӀ restorations after a 2-year clinical follow-up.

Flowable fiber-reinforced versus flowable bulk-fill resin composites: Degree of conversion and microtensile bond strength to dentin in high C-factor cavities

OBJECTIVES

To compare flowable fiber-reinforced and flowable bulk-fill resin composites regarding their degree of conversion (DC) and microtensile bond strength (μTBS) to dentin in high C-factor class I cavities.

MATERIALS AND METHODS

One flowable fiber-reinforced (EverX Flow, GC) and two flowable bulk-fill composites (SDR, Dentsply, and Tetric N-flow Bulk fill, Ivoclar Vivadent) were tested. Regarding DC, 10 cylindrical-shaped specimens were prepared from each material (N = 30), measured using Fourier-Transform Infrared Spectroscopy (FTIR). Regarding µ TBS , class I cavities (4.5 × 4.5 × 3) were prepared on flat dentin surfaces of 30 molars, divided into three equal groups, restored with the three restorative materials, thermocycled, sectioned to create 1 mm × 1 mm cross-sectional beams, then tested using a universal testing machine. Failure mode was assessed using a stereomicroscope. Two-way ANOVA and Tukey's HSD post-hoc tests were used in DC, while One-way ANOVA was used for µ TBS .

RESULTS

The used materials showed statistically significant differences in DC with the fiber-reinforced composite having the highest value. No statistically significant differences were found between the materials regarding their µ TBS .

CONCLUSIONS

Flowable fiber-reinforced composite provided the most DC performance compared to the flowable bulk-fill composites. The three used restorative materials provided comparable bonding ability to dentin in high C-factor cavities.

CLINICAL SIGNIFICANCE

Flowable fiber-reinforced resin composite is preferred as a dentin-replacement material in high-stress bearing areas. However, both flowable fiber-reinforced and bulk-fill resin composites are equally effective in bonding to dentin in high C-factor cavities.

Influence of various antioxidants on micro-shear bond strength of resin composite to bleached enamel

OBJECTIVE

Teeth bleaching causes an immediate decrease in resin composite bonding ability. This study aimed to investigate the influence of various antioxidants on resin composite bond strength to bleached enamel.

MATERIALS AND METHODS

One hundred and ten human maxillary incisors were used. A negative control (group A) (n = 10) was assigned (no bleaching-no antioxidant). The remaining teeth were divided into two groups (n = 50) according to the bleaching agent used: group B (40% hydrogen peroxide) and group C (35% carbamide peroxide). Both groups were subdivided into five subgroups (n = 10). A positive control subgroup (no antioxidant) and other four subgroups according to the antioxidant solution used (10% sodium ascorbate, 10% grape seed extract, 10% green tea extract, and 5% alpha-lipoic acid). After resin composite building, the micro-shear bond strength test was performed. Fracture analysis was examined using a stereomicroscope. Statistical analysis was performed using a two-way analysis of variance and Tukey's HSD post hoc test.

RESULTS

Bond strength significantly decreased after bleaching and there was no significant difference between bleaching agents (P < .0848). Except for alpha-lipoic acid subgroups, the other antioxidants subgroups revealed significantly higher bond strengths than bleached control subgroups (P < .0001).

CONCLUSION

All antioxidants used except alpha-lipoic acid were effective in the reversal of compromised bonding after bleaching.

CLINICAL SIGNIFICANCE

Immediate bonding procedures after bleaching are requisite when bleaching fails to treat teeth discoloration and the direct composite veneer is considered, also when shades of old composite restorations become mismatched after bleaching and should be replaced. Immediate reestablishment of resin bond strengths after bleaching can be achieved by using several antioxidants without the need for delay.