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

Abstract

Objective. To investigate the shear bond strength of self-adhering flowable resin composite, to dentin, after exposing it to Er:YAG laser radiation, at different energy densities. Materials and Methods. Sixty freshly extracted human third molars were randomly divided into five groups (n = 12). In the control group, dentin was left unirradiated, whereas, in the other four groups, dentin was irradiated with Er:YAG laser in noncontact mode (MSP mode = 100 µs; 10 Hz; beam diameter: 1.3 mm; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min), and respectively, with the following level of energy (50 mJ, 60 mJ, 80 mJ, and 100 mJ). Then, self-adhering flowable resin composite was bonded to all prepared dentin surfaces. Shear bond strength (SBS) was applied and fractured surfaces were examined using scanning electron microscopy. Results. SBS values showed significant differences in 60 mJ (P < 0.05) compared to other groups. Morphological evaluation revealed tags or plugs in dentinal tubules, especially when 60 mJ and 80 mJ were used. All four groups tended to leave more residues on the dentin surface, than the control group. Conclusion. Er:YAG dentin irradiation may enhance SBS of the self-adhering flowable resin composite when it is used at the appropriate low level of energy density.

Comparison between Shear Bond Strength of Er:YAG and Er,Cr:YSGG Lasers-Assisted Dentinal Adhesion of Self-Adhering Resin Composite: An Ex Vivo Study

“…In a longitudinal cut, the presence of tags created by resin infiltration confirmed the expectation for the Er:YAG ( Figure 3 b) and Er,Cr:YSGG ( Figure 3 c) effects. Similar results predicted that an increase in the performance of SACs was due to the removal of the smear layer and the opening of dentinal tubules by laser irradiation [ 2 , 20 ], similar to when phosphoric acid was used [ 17 , 36 ], or Ethylenediaminetetraacetic acid (EDTA), which create conditions in which dentin inorganic components were supposed to dissolve [ 37 ]. This would explain the reason behind the significant differences in SBS obtained between the laser-irradiated and nonirradiated groups.…”

“…A significant increase of laser energy could reduce the SBS values of bonding because it may damage, melt and denature the collagen layer and cause cracks and melting of hydroxyapatite in the dentin superficial layer, leading to its recrystallization [ 39 , 40 ]. In a previous study comparing laser multiple energy densities, low energy was proved to increase values of SBS of self-adhering flowable resin composite to dentin [ 20 , 29 ]. Even self-etch adhesive systems can’t perform the same way as multi-step systems regarding bonding strength and stability throughout time [ 41 ].…”

“…This may be explained by the need to eliminate the smear layer in order to facilitate the SAC’s resin interaction with dentinal structure [ 18 ]. Hence, smear layer removal can be performed by the use of Erbium lasers such as Er:YAG (2.94 μm) and Er,Cr:YSGG (2.780 μm) at low level energy density [ 19 , 20 , 21 ]. It was interesting to verify the ability of Erbium lasers to enhance the shear bond strength of SACs.…”

“…It was interesting to verify the ability of Erbium lasers to enhance the shear bond strength of SACs. On the other hand, a previous study reported the efficiency of low level energy (60 mJ) of an Er:YAG laser on SBS values of SACs when compared to nonirradiated dentin [ 20 ].…”

Heat-Polymerized Resin Containing Dimethylaminododecyl Methacrylate Inhibits Candida albicans Biofilm

“…Bond quality test of the interface between two-thirds denture base layer and one-third DMADDM layer was tested with the help of Universal testing machine (5500R, MTS, Cary, NC, USA) [ 35 , 36 ]. The denture base layer was rigidly fixed to the holding arm of the machine.…”