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Abstract

The success and longevity of a resin composite restoration is determined by its good bonding to the tooth structure, with the adhesion being a challenge to dentin due to its complexity and structural heterogeneity. The present study aimed to compare the adhesive strength of dentin conditioned with 18% ethylenediaminetetraacetic acid (EDTA) versus 35% phosphoric acid (H3PO4) in human premolars. Materials and Methods: This in vitro experimental study was performed on 40 human premolars. The occlusal thirds were sectioned and randomly placed into four groups according to the type of dentin conditioning: Group 1 (control), Group 2 (18% EDTA), Group 3 (35% H3PO4) and Group 4 (18% EDTA plus 35% H3PO4). Then, 10,000 thermocycles between 5 +/− 2 °C and 55 +/− 2 °C were applied. Adhesive strength was tested by shearing with a digital universal testing machine at a crosshead speed of 0.75 mm/min. The values obtained were analyzed in megapascals (MPa). The mean and standard deviation were used as measures of central tendency and dispersion. In addition, a one-factor intergroup ANOVA test was applied with Tukey’s post hoc test considering a significance level of p < 0.05. Results: The 18% EDTA and 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the control group that did not receive dentin conditioning (p = 0.047 and p < 0.001, respectively). However, the group conditioned with 18% EDTA did not present significant differences compared to the group conditioned with 35% H3PO4 (p = 0.997). In addition, the group conditioned with 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the groups conditioned with 18% EDTA (p = 0.002) and 35% H3PO4 (p = 0.001). Conclusion: The adhesion of bulk fill resin composite to dentin was favorable when preconditioning was performed using 18% EDTA followed by 35% H3PO4. In contrast, when both etchants were used separately, the bulk fill resin composite showed similar bond strength values in both cases, but significantly lower compared to their sequential application.

2.4. Dentin Conditioning and Resin Composite Bonding

The procedure for each group was as follows ():Group 1: No dentin etching. Only rinsed in water for 5 s, and excess moisture was dried with sterile gauze. Then, a layer of Tetric® N-Bond adhesive was placed with a microbrush, and air was gently applied for 5 s. Finally, a block of Tetric® N-Ceram Bulk-Fill resin composite color A2 was placed and light cured perpendicularly for 10 s at a maximum distance of 1 mm to the upper surface with a Bluephase N LED (Ivoclar Vivadent AG, Schaan, Liechtenstein) at an intensity of 1200 mW/cm2 for 10 s. (). The light intensity of curing unit was previously verified using a radiometer (Bluephase Meter II, Ivoclar Vivadent AG, Schaan, Liechtenstein).Group 2: Dentin etching was performed with 18% EDTA gel for 90 s. Then it was washed with water for 10 s, and the excess moisture was dried with sterile gauze. Then, the adhesive was applied, and the resin composite was placed using the same procedure as group 1 [].Group 3: Dentin etching was performed with 35% H3PO4 gel for 15 s. Then, it was washed with water for 10 s, and the excess moisture was dried with sterile gauze. Then, the adhesive was applied, and the resin composite was placed using the same procedure as groups 1 and 2.Group 4: Dentin etching was performed with 18% EDTA gel for 90 s. Then, it was washed with water for 10 s, and the excess moisture was dried with sterile gauze. Then, 35% H3PO4 gel was applied for 15 s. Then, it was again washed with water, and excess moisture was dried with sterile gauze. Then, the adhesive was applied, and the resin composite was placed using the same procedure as in groups 1, 2 and 3.

Abstract

Methods. Eighty-nine nonvital premolar and molar teeth with periapical lesions (PAI: 3‒4) without any clinical symptoms were included. The patients were randomly assigned to three groups according to the final irrigation solutions used: G1: 2 mL of Qmix (n=29), G2: 2 mL of 17% ethylenediaminetetraacetic acid (EDTA) (n=30), and G3: 2 mL of 2% chlorhexidine gluconate (CHX) (n=30). All the patients were prescribed 100 mg of flurbiprofen to use as needed for pain. The patients were asked to rate their pain status according to the verbal rating scale at 12, 24, 48, and 72 hours, and one week. The data were analyzed using Pearson’s chi-squared test, Fisher’s exact test, and chi-squared analysis with Monte Carlo simulation. The significance level was set at P≤0.05.

Abstract

Results. No significant differences were observed in postoperative pain rates at 12, 48, and 72 hours and one week (P>0.05). However, in the Qmix group, a significantly lower pain level was observed at 24 hours with EDTA and CHX (P=0.019). The rate of mild pain in the EDTA group at 72 hours (18.8%) was significantly higher in premolar teeth than in molar teeth (P=0.012). The moderate pain level in the EDTA group at 12 hours was significantly higher in those>60 years of age (P=0.008).

Patient selection

The method and design of this prospective, randomized, double-blind clinical trial were approved by the Ethics Board of the University (No: 929). The study protocol was published and registered at www.clinicaltrials.gov (identifier: ). Before inclusion, all the patients were informed of the study protocol, aims, complications, and possible risks, and written informed consent was obtained from each patient. Patients who met the inclusion criteria were treated by a single endodontist (SIY) from the Faculty of Dentistry, Department of Endodontics, between October 2019 and February 2020.

Root canal treatment procedures

Group 2 (EDTA, n = 30): After applying 2 mL of saline solution to each root canal for 30 sec, 2 mL of 17% EDTA was applied for 60 seconds.