Time sensitivity associated with the application of water-based all-in-one adhesive system

This in vitro study was performed to investigate effect of delayed composite application on dentin bonding durability of water-based all-in-one self-etch adhesive system using micro-tensile bond strength (MTBS) testing. Fifteen freshly extracted, non-carious premolar teeth were randomly selected. After removing the roots, the teeth were occlusally trimmed to expose superficial dentin. Then, the exposed occlusal dentin was bonded with a self-etching adhesive (Tetric-N Bond self-etch; Ivoclar/Vivdent) according to the manufacturer’s instructions. After that, the samples were divided equally into 3 groups based on the time of application of Tetric-N Ceram composite resin (Ivoclar/Vivdent, Liechtenstein). In group 1, the composite build-up was carried out immediately after curing the adhesive, and polymerized according to the manufacturer instructions. In groups 2 and 3, the samples were restored after 1 and 5 min following adhesive curing, respectively. After 24 h storage, each bonded sample was sectioned into beams (0.7 mm × 0.7 mm) for MTBS testing. Results of the MTBS were analysed and tested using one-way ANOVA and post hoc Tukey test at significance level of 5%. The results showed that applying composite restoration immediately after adhesive curing gave strength of 11 ± 6 MPa. Composite application after curing the adhesive by 1 and 5 min showed 16 ± 8 MPa and 11 ± 5 MPa, respectively. The 1 min delayed application group had significantly higher bond strength than the other tested groups (p > 0.05). In conclusion, delaying the composite application after polymerization of water-based all-in-one adhesive for 1 min showed better bond strength

Comprehensive Characterization of Blue Wire NiTi File Failure: A Comparative Analysis of Cyclic Fatigue and Torsional Resistance Properties

This study compared the fatigue resistance and elemental composition of two blue heat-treated nickel–titanium (NiTi) files used in root canal preparation as follows: Tia Tornado Blue (TTB) and Race Evo (RE) file systems. For cyclic fatigue testing, the two systems were tested where each file was rotated inside an artificial metal canal submerged in either sodium hypochlorite or saline solution until fracture. Time to fracture was recorded. For torsional fatigue testing, the file tip was secured while the file was allowed to rotate at a fixed rate until fracture. Torque at failure was recorded. The two experiments were performed at simulated body temperature and the length of fractured segments was measured. Statistical analysis was carried out with a significance level (p-value) set at 5%. The mean cycles to fracture for RE were superior to that of TTB irrespective of the solution used (p < 0.05). TTB’s cyclic fatigue resistance decreased in NaOCl (p < 0.0001). RE demonstrated lower torque at failure (p = 0.002). All files were fractured at comparable lengths (p = 0.218). Although RE is considered more resistant to cyclic fatigue, it showed inferior torsional resistance compared with TTB. The NaOCl negatively affected the TTB’s cyclic fatigue resistance

Evaluation of microleakage in class-II bulk-fill composite restorations

Background/purpose: Despite the clinical appeal of restoring deep class II cavities in single increment using bulk-fill resin composite, sealing of bulk-filled composite restorations is a concern. This study evaluated interfacial adaptation of bulk-fill composite restoration to axial wall and gingival floor of class II cavities using cross-polarization optical coherence tomography (CP-OCT). Materials and methods: Box-shaped class II cavities were prepared in extracted molars and divided into three groups (n = 7) according to adhesive used; Clearfil SE Bond 2 (SE2), Tetric-N Bond Self-Etch (TSE) or Tetric-N Bond Universal (TNU). All adhesives were applied in self-etch mode and according to manufacturers' recommendation. Then, preparations were bulk-filled with Filtek Bulk Fill Posterior Restorative resin composite and immersed in a contrast agent. Tomographic images of axial wall and gingival floor of each restoration were obtained by CP-OCT (IVS-300, Santec) with a central wavelength of 1330 nm and were imported to an image analysis software to quantify microleakage. Results: Mann–Whitney U test showed statistically significant difference in microleakage percentage between the groups at both axial wall and gingival floor (p < 0.05). SE2 group had the lowest percentage of microleakage (p < 0.05), as only few cross-sections showed areas of reflections from contrast agent penetrating into axial wall (8.23 ± 6.8) and gingival floor (7.07 ± 4.1), followed by TNU group (18.13 ± 12.9 axially and 30.61 ± 11.9 gingivally). Microleakage was frequently observed at the axial wall and gingival floor of TSE group, showing the highest percentages of 25.50 ± 12.5 and 36.97 ± 10.2, respectively (p < 0.05). Conclusion: All tested groups exhibited different extent of interfacial microleakage, however, two-step self-etch adhesive yielded superior adaptation in comparison to one-step self-etch adhesive and universal adhesive

Psychological Distress among Undergraduate Dental Students in Saudi Arabia and Its Coping Strategies—A Systematic Review

The objective of this paper was to evaluate the studies that have reported on psychological issues among dental students in Saudi Arabia and to develop coping strategies to overcome these mental health-related issues. The present systematic review is in accordance with the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search for the articles was carried out in the electronic databases by four independent researchers. The data search was performed in the electronic search engines like PubMed, Google Scholar, Web of Science, Scopus, Medline, Embase, Cochrane and Saudi Digital Library for scientific research articles published from January 2000 until December 2020. STROBE guidelines were adopted for qualitative analysis of six articles which met the eligibility criteria. The analysis of the literature revealed that most of the studies included were conducted in the past 8 years in different regions of Saudi Arabia. Findings of this systematic review clearly state that dental students in Saudi Arabia experience higher levels of depression, stress and anxiety and stress during their education period, with a higher stress for female students compared to male students. There is an urgent need to introduce interventional programs and preventive strategies to overcome the long-term effects.</jats:p