IADR Abstract Archives
Effects of Fiber-reinforced Increment on Bond Strength to Deep Dentin
Objectives: Bonding to cavity floor dentin may be challenging in large deep composite restorations, even using state-of-the-art bulk-fill composites. We investigated whether an increment of composite reinforced with plasma-treated leno weaved ultra-high-molecular-weight polyethylene fiber (PTLWUHMWPEF) at the base of cavity affected microtensile bond strength to deep cavity dentin.
Methods: High C-factor occlusal preparations (3 x 3 x 4 mm3) were performed on 24 intact human molars. The preparation was treated with Clearfil SE Bond 2 (Kuraray Noritake Dental) and filled using 3 placement techniques: 1) SureFil SDR flow (SDR, Dentsply Sirona) placed in bulk (BLK), 2) SDR placed in two unequal increments (INC) and 3) SDR placed after an increment of composite reinforced with Ribbond Ultra fiber (Ribbond) was placed at the cavity floor (FRC). After 24 hours 37°C water storage, specimens were sectioned using diamond saw to create 0.7 x 0.7 mm2 beams that were subjected to the microtensile bond strength (MTBS) test. MTBS (MPa) values were averaged per tooth considering pre-test failures. One-way ANOVA with post-hoc Tukey HSD was used to compare MTBS at significance level of alpha=0.05. The dentin side of the beam was observed by scanning electron microscopy (SEM).
Results: MTBS values were 13.8±7.6, 31.7±12.5 and 28.3±8.5 (mean±SD) for BLK, INC and FRC groups. While there was no significant difference between FRC and INC, both were different from BLK (p<0.05). No pre-test failures were observed in FRC group. SEM micrographs showed that the separation under load in BLK and INC was predominantly at the dentin-adhesive interface, while in FRC it always involved the fiber-reinforced increment (figure).
Conclusions: A thin layer of composite applied before the bulk-fill composite significantly improved bond strength to deep cavity floor. When fiber was incorporated in to this increment, bonding results were more consistent and dentin interface remained protected under stress.
Methods: High C-factor occlusal preparations (3 x 3 x 4 mm3) were performed on 24 intact human molars. The preparation was treated with Clearfil SE Bond 2 (Kuraray Noritake Dental) and filled using 3 placement techniques: 1) SureFil SDR flow (SDR, Dentsply Sirona) placed in bulk (BLK), 2) SDR placed in two unequal increments (INC) and 3) SDR placed after an increment of composite reinforced with Ribbond Ultra fiber (Ribbond) was placed at the cavity floor (FRC). After 24 hours 37°C water storage, specimens were sectioned using diamond saw to create 0.7 x 0.7 mm2 beams that were subjected to the microtensile bond strength (MTBS) test. MTBS (MPa) values were averaged per tooth considering pre-test failures. One-way ANOVA with post-hoc Tukey HSD was used to compare MTBS at significance level of alpha=0.05. The dentin side of the beam was observed by scanning electron microscopy (SEM).
Results: MTBS values were 13.8±7.6, 31.7±12.5 and 28.3±8.5 (mean±SD) for BLK, INC and FRC groups. While there was no significant difference between FRC and INC, both were different from BLK (p<0.05). No pre-test failures were observed in FRC group. SEM micrographs showed that the separation under load in BLK and INC was predominantly at the dentin-adhesive interface, while in FRC it always involved the fiber-reinforced increment (figure).
Conclusions: A thin layer of composite applied before the bulk-fill composite significantly improved bond strength to deep cavity floor. When fiber was incorporated in to this increment, bonding results were more consistent and dentin interface remained protected under stress.
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