Effect of radiotherapy on the surface roughness and microhardness of contemporary bioactive restorative materials.

OBJECTIVE: The aim of this in vitro study was to evaluate the effect of radiotherapy on the surface microhardness and roughness of different bioactive restorative materials. MATERIALS AND METHODS: A total of 60-disc specimens (5 mm × 2 mm) were performed in four groups (n = 15 each) from Equia Forte HT, Cention N, Activa Bioactive Restorative, and Beautifil II. Following the polishing procedure (600, 1000, 1200 grit silicon carbide papers), all specimens were irradiated at 2 Gy per fraction, five times a week for a total dose of 70 Gy in 30 fractions over 7 weeks. Before and after the irradiation, the specimens were analyzed regarding the surface roughness and microhardness. Surface morphology was also analyzed by scanning electron microscopy. Kruskal-Wallis test, Wilcoxon test, and paired sample t-test were used for statistical analysis. RESULTS: Significant differences were found after radiation with increased mean roughness of both Cention N (p = 0.001) and Beautifil II (p < 0.001) groups. In terms of microhardness, only the Beautifil II group showed significant differences with decreased values after radiation. There were statistically significant differences among the groups' roughness and microhardness data before and after radiotherapy (p < 0.05). CONCLUSION: The effect of radiotherapy might differ according to the type of the restorative material. Although results may differ for other tested materials, giomer tends to exhibit worse behaviour in terms of both surface roughness and microhardness. CLINICAL RELEVANCE: In patients undergoing head and neck radiotherapy, it should be taken into consideration that the treatment process may also have negative effects on the surface properties of anti-caries restorative materials.

Effects of Different Whitening Agents on the Color and Translucency of Different Resin Composites.

Objectives: To examine the effects of different whitening agents on the color and translucency of different resin composites, in vitro. Material and methods: A total of 315 specimens (10.0 ×2.0 mm) were fabricated from two microhybrid (G-aenial anterior [G-Ant]) and (G-aenial posterior [G-Post]) and a nano hybrid (G-aenial A'CHORD [ G-ACH]) resin composites and each group was randomly distributed into seven experimental groups (n=15) as follows; 1- control (C); 2- in-office whitening agent (IOW); 3- at-home whitening agent (AHW); 4- prefilled tray (PT); 5- whitening pen (WP); 6- whitening toothpaste (WT) and 7- whitening mouthwash (WMW). The specimens were subjected to staining except control group before application of the different whitening procedures. The color of specimens was measured after 24 h (T0), after staining (T1) and after whitening (T2). Color change [CIEDE2000 (ΔE00)], translucency parameter (TP) values and changes in whiteness index (WID) were calculated. Data were analyzed statistically (p<0.05). Results: No significant 𝑊ID differences were detected among the tested resin composites at T0 and T1 (p>0.05), whereas a significant difference was observed at T2 (p<0.005). AHW and IOW produced higher color change than PT, WP, WT and WMR. Significant TP changes were found after the application of IOW and AHW in G-Ant. Conclusion: The effect of whitening products on the whitening index, color and translucency of resin composites are material and substrate dependent.

Shear bond strengths of two newly marketed self-adhesive resin cements to different substrates: A light and scanning electron microscopy evaluation.

The purpose of this in vitro study was to compare the shear bond strengths (SBSs) of two newly marketed self-adhesive resin cements (RCs) to enamel, dentin, and lithium disilicate (LiSi) glass ceramic block. Forty-eight enamel and 48 dentin substrates were obtained from sound human molars. Additionally, 6 × 7 × 5 -mm- sized 24 specimens were produced from LiSi glass ceramic blocks. The tooth specimens were randomly assigned into four groups (n = 12) according to the surface treatments: (1) G-CEM ONE (GCO), (2) G-CEM ONE Adhesive Enhancing Primer (GCO-AEP) + GCO, (3) RelyX Universal (RXU), and (4) Scotchbond Universal Plus (SUP) + RXU. LiSi specimens were randomly divided into two groups (n = 12): (1) G-MultiPrimer (GMP) + GCO and (2) SUP + RXU. Following the RC applications, all specimens were kept in 100% humidity at 37°C for 24 hr and then submitted for SBS testing in a universal testing machine (1 mm/min). Data were analyzed by Welch's, one-way analysis of variance and two independent samples t tests. The nature of failures was examined under a light microscope, and scanning electron microscopy analyses were also performed for interfaces. GCO and RXU showed similar SBS to enamel (p > .05), and the use of adhesives resulted in improved SBS (p < .05). No difference was detected between GCO-AEP + GCO and SUP + RXU. The GCO-AEP + GCO exhibited the highest SBS to dentin (p < .05), followed by GCO ≥ SUP + RXU > RXU (p < .05). There was no significant difference between SBSs of two RCs to LiSi blocks (p > .05). No cohesive failure was determined for the tested groups by light microscope. The use of adhesives prior to the application of self-adhesive RCs improved their bonding to tooth tissues. GCO demonstrated superior SBS to dentin, whereas both self-adhesive RCs generated similar SBS to enamel and LiSi glass ceramic surfaces.

Professional motivations and perceptions of senior dental students in the distance education period during the first year of the Covid-19 pandemic.

Purpose: Dental students are particularly prone to be affected by the global emergency of Coronavirus-19 (Covid-19) pandemic. The aim of this study was to evaluate the professional motivations and perceptions of senior dental students during the distance education period due to pandemic. Materials and methods: The data was collected via an online questionnaire, including questions related to students' professional motivation and perceptions, and views about preventive dentistry. For identifying the distress levels, Turkish version of Depression Anxiety Stress Scale (DASS)-21 was used. Descriptive statistics and marginal homogeneity test were used for statistical analysis. Results: A total of 114 (83 female, 31 male) students, with the mean age of 23.7±1.03 participated the study. Statistically significant changes were observed on the students' career plans (p<0.001); fear about getting and transmitting infectious diseases (p<0.001); and satisfaction about their profession (p<0.001) during the Covid-19 pandemic. Motivation loss was determined on the participants. Conclusion: There is an urgent need for revision on dental education in order to ensure the students be competent to provide oral health service that can meet the latest needs and achieve professional self-confidence without deterioration on their professional motivation and perceptions. Crisis-oriented psychological support programs should be provided for students. Some improvements should be structured in terms of preventive dentistry issues, both for dental education and dental health service aspects.

Does Rubbing of Universal Adhesive Reduce the Negative Effect of Saliva on Adhesion?

Purpose: To evaluate in vitro the effect of saliva contamination on bond strength of a universal adhesive applied with actively (with rubbing motion) and passively (without rubbing motion). Materials and Methods: A total of 144 bovine dentin samples were used, and the universal adhesive, Clearfil Universal Bond Quick, was either applied in accordance with the manufacturer's instructions (passive application) or applied with rubbing motion for 10 s (active application). These 2 groups were divided into 6 subgroups according to saliva contamination (n = 12): 1. control: etch-and-rinse (no saliva); 2. control: self-etch (no saliva); 3. etching/saliva/bonding; 4. etching/bonding/saliva; 5. saliva/bonding; 6. bonding/saliva. A resin composite, Filtek Ultimate, was filled into a polyethylene mold (0.9 mm diameter, 1.2 mm height) on the surfaces. Samples were subjected to microshear bond strength testing, and five specimens from each group were examined using SEM. Resin-dentin interfaces were also observed using transmission electron microscopy (TEM). All failure modes were determined using light microscopy. Statistical analyses were performed with two-way ANOVA, the Kruskall-Wallis test, and the Mann-Whitney U-test (p < 0.05). Results: Active-application groups showed statistically significantly higher bond strengths than did passive groups, regardless of adhesive strategy and saliva contamination (p < 0.05). Application of Clearfil Universal Bond Quick in self-etch mode with rubbing motion improved the µSBS among control groups (p < 0.05). The active application did not make a significant difference among the active groups (p > 0.05), except in group 2. Groups 2 and 5 showed significantly higher µSBS than group 3 among the passive groups (p < 0.05). Conclusion: Rubbing the universal adhesives without any prior etching may increase the dentin bond strength. Following etching, passive application of the universal adhesive (without any additional rubbing motion) could affect the bonding to dentin in the presence of saliva.

Does laser etching have an effect on application mode of a universal adhesive?-A microleakage and scanning electron microscopy evaluation.

This study aimed to evaluate the microleakage of a universal adhesive's different application modes incorporated with Er,Cr:YSGG laser on Class V resin composite restorations. Sound human molar teeth (n = 30) were used for microleakage evaluations. Specimens with 60 standardized Class V cavities were divided into five groups according to the adhesive modes of universal adhesive, Adhese Universal (n = 12). Group 1-etch-and-rinse mode with phosphoric acid; Group 2-etch-and-rinse mode with Er,Cr:YSGG laser; Group 3-selective-etch mode with phosphoric acid; Group 4-selective-etch mode with Er,Cr:YSGG laser; Group 5-self-etch. After restorations were performed with a resin composite, Tetric N-Ceram, the specimens were polished and subjected to thermocycling (10,000X). Following immersion in 0.5% basic fuschin for a day, the teeth were sectioned and the degree of microleakage was determined along the tooth-resin composite interface using a light microscopy(40X). Five specimens from each group were examined by scanning electron microscopy. The Kruskal-Wallis, Siegel Castello, and Wilcoxon tests were used for statistical analyses (α = .05). At the enamel margins, significant differences were obtained among the groups (p < .05). Significantly higher microleakage scores were detected in Group 5 in comparison with Groups 1, 2, and 3. There were no significant differences between different adhesive strategies at the dentin margins (p > .05). While analyzing enamel and dentin microleakage scores, no statistically significant differences were observed in Groups 4 and 5 (p > .05). The laser application time and the adhesive modes of universal adhesives could affect the microleakage at the enamel margins. Different adhesive modes of universal adhesives combined with laser etching had no influence on the microleakage scores of dentin margins.

Thirty-six-month clinical evaluation of different adhesive strategies of a universal adhesive.

AIM: The aim of this clinical trial was to evaluate and compare the performance of a universal adhesive with different adhesive strategies in the restoration of non-carious cervical lesions (NCCLs) over a 36-month period. MATERIAL AND METHOD: One hundred sixty-five NCCLs in 35 patients (13 female, 22 male) with at least 3 lesions each were included in this study. Three groups were formed according to the adhesive strategy used (n = 55): selective-etch mode, etch-and-rinse mode, or self-etch mode of a universal adhesive, Single Bond Universal. The same nanofilled resin composite, Filtek Ultimate, was used for all restorations by a single operator. The restorations were evaluated by two calibrated examiners at baseline and at 6, 12, 18, 24, and 36 months in accordance with the modified USPHS criteria. The chi-square test was used for intergroup comparison and Cochran's Q test for intragroup comparison (∝ = 5%). RESULTS: At 36 months, the recall rate was 98.1% and three restorations, one from each group, had failed because of retention loss (P > 0.05). The self-etch mode group showed 17 bravo scores for both marginal staining and marginal adaptation after 3 years, which was significantly different from the selective-etch and etch-and-rinse groups (P < 0.05). For all groups, the only statistically significant difference was found when baseline and 36-month evaluations were compared in terms of marginal staining (P = 0.000). When the marginal adaptation values at 36 months were compared with those at the baseline, statistically significant differences were found in the etch-and-rinse and self-etch mode groups (P < 0.05). Neither secondary caries nor postoperative sensitivity was observed at any recall. CONCLUSION: All adhesive modes showed similar retention rates. Although all restorations were clinically acceptable, restorations in self-etch mode showed less satisfying performance for marginal staining and marginal adaptation. CLINICAL RELEVANCE: At the end of 36 months, the Single Bond Universal adhesive received acceptable scores according to the modified United States Public Health Service (USPHS) criteria. However, clinicians should be aware that its use in self-etch application mode tends to result in marginal staining and marginal deterioration when compared with etch-and-rinse and selective-etch application modes.