Objectives:The aim of the current study was to evaluate the resin-dentin micro-tensile bond strength (μ-TBS) using 2 types of universal adhesives with etch-and-rinse and self-etch approaches after 24 hours and 6 months of water storage.
Materials and Methods:A total of 20 extracted non-carious human molars were used in this study. Teeth were equally and randomly divided into 2 groups (N= 10 teeth) according to the type of adhesive used; Group I; Adhese® Universal and Group II; Single Bond Universal. Each group was further subdivided into 2 equal subgroups (n=5 teeth) according to the bonding approach used; Subgroup A; using the self-etch (SE) approach and Subgroup B; using the etch-and-rinse (ER) approach. After bonding, each tooth was built up by resin composite, cut into sticks (0.9 mm x 0.9 mm) and stored in distilled water at 37˚C for 24 hours and 6 months. Then, each stick was stressed under tension until failure using a simplified universal testing machine at a crosshead speed of 1 mm/min. Data were statistically analyzed using One-Way ANOVA, Two-Way ANOVA and Tukey HSD Tests. After μ-TBS testing, all debonded surfaces were observed using a stereomicroscope at 50X magnification to determine the modes of failure, which were categorized as adhesive, cohesive or mixed failure.
Results:After 24 hours of water storage, there was no significant difference between the μ-TBS exhibited by Adhese Universal using both SE and ER approaches while both approaches differed significantly when using Single Bond Universal (P=0.0003). Furthermore, there was no significant difference when comparing the μ-TBS means of SE groups or ER groups of both adhesive systems. After 6 months of water storage at 37˚C, there was a significant decrease in the μ-TBS values of all groups (p<0.0001) except when Adhese Universal was used with SE approach, there was no difference between the 24 h and the 6 month-groups (p=0.1449). The failure mode analysis was consistent with the μ-TBS test results as the number of adhesive failures increased with decreased bond strength values.
Conclusions:When bonding resin-based composite restoratives to dentin, a separate acidetching step is not required when using Adhese Universal, but it is preferred with Single Bond Universal adhesive. Aging markedly contributes to bond degradation of universal adhesives.
IntroductionIn Saudi Arabia, limited studies have evaluated factors including epidemiologic, clinical, and laboratory findings that are associated with COVID-19 disease. The aim of this paper was to identify laboratory parameters used in King Abdulaziz University Hospital which show an association with disease severity and patient outcome in the form of mortality.MethodsAge, gender, medical history, and laboratory parameters were all retrospectively assessed concerning disease severity and disease outcome in a total of 111 COVID-19 patients at King Abdulaziz University Hospital between July 2020 and August 2020. Patients were categorized into mild disease if they did not require ward admission, moderate if they met the Ministry of Health criteria for isolation ward admition, and severe if they were admitted to the ICU.ResultsAge but not gender was associated with the disease severity X2 (4, N = 110) = 27.2, p <0.001. Of all laboratory parameters on admission, only the levels of Albumin appeared to be significantly associated X2 (2, N =70) = 6.6, p <0.05 with disease severity. Age but not gender was also significantly associated with disease outcome X2 (2, N = 110) = 12.8, p < 0.01. Interestingly, RBC count also showed a significant relation with disease outcome X2 (2, N = 71) = 6.1, p <0.05.DiscussionThis study provides more understanding of the laboratory characteristics in our part of the world to efficiently manage the disease.
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