Influence of Nd:YAG laser on intrapulpal temperature and bond strength of human dentin under simulated pulpal pressure

Abstract

The aim of this study was to evaluate the effects of simulated pulpal pressure (SPP) on the variation of intrapulpal temperature (ΔT) and microtensile bond strength (μTBS) to dentin submitted to an adhesive technique using laser irradiation. One hundred sound human molars were randomly divided into two groups (n = 50), according to the presence or absence of SPP (15 cm H2O). Each group was divided into five subgroups (n = 10) according to Nd:YAG laser energy (60, 80, 100, 120, 140 mJ/pulse). The samples were sequentially treated with the following: 37 % phosphoric acid, adhesive (Scotchbond Universal), irradiation with Nd:YAG laser (60 s), and light curing (10 s). ΔT was evaluated during laser irradiation using a type K thermocouple. Next, a composite resin block was build up onto the irradiated area. After 48 h, samples were submitted to microtensile test (10 kgf load cell, 0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey tests (p = 0.05). ANOVA revealed significant differences for ΔT and TBS in the presence of SPP. For ΔT, the highest mean (14.3 ± 3.23 °C)(A) was observed in 140 mJ and without SPP. For μTBS, the highest mean (33.4 ± 4.15 MPa)(A) was observed in 140 mJ and without SPP. SPP significantly reduced both ΔT and μTBS during adhesive procedures, lower laser energy parameters resulted in smaller ΔT, and the laser parameters did not influence the μTBS values.

Exposed Dentin: Influence of Cleaning Procedures and Simulated Pulpal Pressure on Bond Strength of a Universal Adhesive System

“…the “total-etch” mode) as compared to the “self-etch” mode, but phosphoric acid etching actually caused a reduction in bond strength when specimens had been prepared in the presence of simulated pulpal pressure, leading to partial rejection of the second hypothesis. This finding is in accordance with that of Silva et al [12] and may be explained as follows: Simulated pulpal pressure implies a constant intrinsic wetness of the dentin. If the presence of water did not hamper infiltration of the self-etch adhesive system to its reported depth of less than 1 μm [21,22], it may have hindered complete infiltration of the adhesive system into the 5 μm thick zone of totally demineralized dentin caused by phosphoric acid etching and thus compromised the quality of the hybrid layer and of the adhesive bond.…”

“…However, there is no information about how pre-treatment of dentin with these two powders affects bond strength of adhesive systems and resin composite. Consequently, the aim of the present study was to investigate bond strength of resin composite and a universal adhesive system (Scotchbond Universal; 3M ESPE) to dentin under different conditions, including absence or presence of simulated pulpal pressure since clinically, pulpal pressure may lead to moisture in the form of dentinal fluid, which has previously been shown to potentially compromise bonding of adhesive systems [12,13]. …”

Microtensile bond strength of universal adhesives to flat versus Class I cavity dentin with pulpal pressure simulation

“…Pulpal pressure was previously simulated during adhesive application and polymerization but not during aging . Furthermore, different test designs were used to simulate pulpal pressure .…”

Effect of chlorhexidine application or Nd:YAG laser irradiation on long-term bond strength of a self-etching adhesive system to dentin

“…The Clearfil SE Bond adhesive system uses the self-etching approach, in which dentin demineralization and monomer infiltration occur simultaneously, unlike the etch-and-rinse approach, which requires the application of phosphoric acid, and which demineralizes dentin more deeply [5]. By using the etch-and-rinse approach, it has been demonstrated that Nd:YAG irradiation does not alter bond strength to dentin [29,30]. This suggests that acid conditioning may be important for adhesion in Nd:YAG irradiated tissues.…”