Effect of different surface treatments on the microtensile bond strength of two self-adhesive flowable composites

Abstract

The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) of two different self-adhesive flowable composite materials (SACs) to dentin. Forty extracted human molars were horizontally flattened to expose the dentin surfaces. The teeth were divided into eight groups according to the surface treatments (acid etching, Er:YAG laser quantum square pulse (QSP) mode, and Er:YAG laser medium-short pulse (MSP) mode at 10 Hz, 1.2 W, 120 mJ, and control-SiC) and SAC type (Vertise Flow and Fusio Liquid Dentin) (n = 5). Light cured 4-mm-high composite build-ups were made on the dentin surfaces, and the specimens were sectioned into serial sticks (n = 15). Later, the specimens were attached to microtensile testing machine and tensile force was applied at a crosshead speed of 1 mm/min until failure occurred. The failure modes were evaluated using a stereomicroscope at ×40 magnification, and one sample from each group was used for scanning electron microscopy (SEM) evaluation. The data were analyzed with two-way ANOVA and Tukey's HSD test (α = 0.05). In all surface treatment groups along with the control groups, Vertise Flow showed better μTBS than the Fusio Liquid Dentin with the exception of the Er:YAG MSP mode surface treatment (p < 0.05). Etching with phosphoric acid and the Er:YAG QSP mode surface treatment significantly increased the μTBS of Vertise Flow (p < 0.05). Etching with phosphoric acid, Er:YAG QSP mode surface treatment, and Er:YAG MSP mode surface treatment significantly increased the μTBS of Fusio Liquid Dentin (p < 0.05). The μTBS of Vertise Flow was higher than the μTBS of Fusio Liquid Dentin. The Er:YAG laser irradiation increased the μTBS of both self-adhesive flowable resin composites in two pulse modes tested (MSP or QSP). However, the highest μTBS was recorded when Vertise Flow was applied with acid etching.

Effect of dentin laser irradiation at different pulse settings on microtensile bond strength of flowable resin

“…The laser-and acid-etched specimens served more regular surfaces than only laseretch groups and were similar with those of the acid-etch group. The SEM views of the present study are aligned with the study of Altunsoy et al 30) . When we evaluate the fractured surfaces after debonding in both laser irradiated groups, resin shows more integration to the dentin surface in total etch groups than self etch groups.…”

“…Altunsoy et al reported that the highest μTBS was recorded when Vertise Flow (self-adhesive flowable resin) was applied with acid etching, with no statistically significant differences between the QSP and MSP modes. However, in the same study, the highest μTBS for Fusio Liquid Dentin (self-adhesive flowable resin) was recorded with the MSP mode 30) . Filtek TM Ultimate Flowable Restorative was used in the current study.…”

The Effect of Energy Densities on the Shear Bond Strength of Self-Adhering Flowable Composite to Er:YAG Pretreated Dentin

“…This indicates a decline in the concentration of Ca. This phenomenon is similar to decalcification of the tooth [20]. Moreover, Brulat et al mentioned that dentin conditioning by low fluence with Er:YAG laser improved adhesion of composite resin to dentin [17, 21].…”

“…Affected area is less intense in the surrounded irradiated surface and deeper in the tissue layers [18]. This thermal damage increases gradually with the intensification of laser energy [20] and when temperature exceeds 225°C. Collagen fibers start to denature and no reversion to initial conformation is observed after rehydration [19].…”

Application of Laser Irradiation for Restorative Treatments

“…Bond strength of composite resin is another concerning issue in released literature [40-44]. Some studies experienced “laser etching effect” by irradiating laser to prepare sufficient surface roughness and permitting mechanical interlocking with adhesive resins [22, 45].…”