COVID-19 pandemic and its impact on dental students: A multi-institutional survey.

PURPOSE/OBJECTIVES: To investigate dental students' perceptions and concerns regarding the COVID-19 pandemic, their coping strategies and support resources, and their perceived stress levels. METHODS: A customized 19-item survey and the perceived stress scale (PSS) were applied to undergraduate dental students from the US, Spain, Ireland, Chile, India, and Brazil between April 10 and July 5, 2020. Linear modeling and mediation analysis were used to explore the relationships among demographics, stressors, coping mechanisms, social support, and stress RESULTS: A total of 4475 students responded to the survey. The majority (72.4%) were women, and 52.3% had no COVID-19 training at the time of the survey. The students reported that they had to accommodate to changes in patient care (96.6%) and didactic learning (95.2%) activities, while 88.5% of the respondents indicated at least one of their courses moved online. Transition to online courses went "smoothly with some troubles" for 51.8% of the respondents, and 48.3% perceived the faculty as prepared for the online transition; however, 45.9% reported feeling extremely concerned about the impact of COVID-19 on their education. The average PSS score was 21.9 of 40 (moderate stress). Multivariate models were built for participants with full data (n = 3899). Being male, having completed more dental coursework, and perceiving a smoother transition were associated with lower PSS scores; more concern about academic progress was associated with higher PSS. Faculty support mediated the relationship between a smoothness of transition and concern about academic progress and PSS scores CONCLUSION: Stress caused by the pandemic may be alleviated by smoother transition and good faculty support.

In vivo biocompatibility of silicon dioxide nanofilm used as antimicrobial agent on acrylic surface.

the focus ofthis study was to testthe hypothesisthatthere would be no difference betweenthe biocompatibility of silicon dioxide nanofilms used as antimicrobial agents. Sixty male Wistar rats were divided into 4 groups (n=15): Group C (Control,Polyethylene), Group AR (Acrylic Resin), Group NP (Acrylic Resin coated with NP-Liquid), Group BG (Acrylic Resin coated with Bacterlon).the animals were sacrificed with 7,15 and 30 days and tissues analyzed as regardsthe events of inflammatory infiltrate, edema, necrosis, granulation tissue, mutinucleated giant cells, fibroblasts and collagen. Kruskal-Wallis and Dunn tests was used (P<0.05). Intense inflammatory infiltrate was shown mainly in Groups BG and AR, with significant difference from Control Group inthe time interval of 7days (P=0.004). Necrosis demonstrated significant difference between Group BG and Control Group (P<0.05) inthe time intervals of 7 days. For collagen fibers,there was significant difference betweenthe Control Group and Groups AR and BG inthe time interval of 7 days (P=0.006), and between BG and Control Groups inthe time intervals of 15 days (P=0.010).the hypothesis was rejected. Bacterlon demonstratedthe lowest level, and NP-Liquid Glassthe highest level of tissue compatibility, and best cell repair.the coating with NP-Liquid Glass was demonstrated to be highly promising for clinical use.

Histological analysis of biocompatibility of different surgical adhesives in subcutaneous tissue.

The focus of this study was to test the hypothesis that there would be no difference between the biocompatibility of cyanoacrylate-based adhesives in rat subcutaneous tissues. In total, 60 male Wistar rats were used, and divided into four groups (n = 15): Group C (control, PVA-polyvinyl alcohol sponge), Group NO (N-butyl-2-octylcyanoacrylate), Group NH (n-hexyl-cyanoacrylate), and Group EC (Ethyl-cyanoacrylate). The animals were sacrificed after time intervals of 7, 15, and 30 days and tissues were analyzed under optical microscope as regards the events of inflammatory infiltrate, edema, necrosis, granulation tissue, giant cells, young fibroblasts, and collagen formation. The results were statistically analyzed by the Kruskal-Wallis and Dunn tests (p < .05). Significant inflammatory infiltrate was shown for all the adhesives in the time intervals of 7 (p = .004) and 15 days (p = .003). In the time interval of 30 days, moderate inflammatory infiltrate was observed in Groups NH and EC, with significant difference from Control (p = .001). The quantity of collagen fibers in all the experimental groups showed significant difference compared with Control in the time intervals of 7 (p = .002) and 15 days (p = .001), at 30 days only Group EC showed a smaller quantity of collagen fibers in comparison with Control (p = .001). The hypothesis was rejected. The adhesive N-butyl-2-octylcyanoacrylate had less influence on the inflammatory intensity of multinucleated giant cells. Ethyl-cyanoacrylate demonstrated the lowest level of biocompatibility among the adhesives, but its use in clinical practice may be promising for coaptation of smaller edges of superficial tissue. Surgical adhesives were shown to be feasible for clinical use in substitution of conventional suturing. Ethyl-cyanoacrylate should be used with caution due to its greater influence on tissues.

The in vitro antimicrobial activity of natural infant fluoride-free toothpastes on oral micro-organisms.

PURPOSE: The objective of this study was to evaluate the antimicrobial activity of six toothpastes for infants: 3 fluoride-free experimental toothpastes--cashew-based, mango-based and without plant extract and fluoride compared with 2 commercially fluoride-free toothpastes and 1 fluoridated toothpastes. METHODS: Six toothpastes for infants were evaluated in this study: (1) experimental cashew-based toothpaste; (2) experimental mango-based toothpaste; (3) experimental toothpaste without plant extract and fluoride (negative control); (4) First Teeth brand toothpaste; (5) Weleda brand toothpaste; and (6) Tandy brand toothpaste (positive control). The antimicrobial activity was recorded against Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, and Candida albicans using the agar plate diffusion test. RESULTS: First Teeth, Weleda, mango-based toothpaste, and toothpaste without plant extract presented no antimicrobial effect against any of the tested micro-organisms. Cashew toothpaste had antimicrobial activity against S mutans, S sobrinus, and L acidophilus, but it showed no antimicrobial activity against C albicans. There was no statistical difference between the inhibition halo of cashew and Tandy toothpastes against S mutans and L acidophilus. CONCLUSIONS: Cashew fluoride-free toothpaste had inhibitory activity against Streptococcus mutans and Lactobacillus acidophilus, and these results were similar to those obtained for fluoridated toothpaste.

Child toothbrush abrasion effect on ionomeric materials.

The purpose of the study was to evaluate the abrasive effect of different toothbrushes-soft-cross bristles (CB), extra-soft-parallel bristles (ES), and soft-parallel bristles (S)-on the surface roughness of conventional (C) and resin-modified (V) glass ionomer cements in vitro. Eight specimens of each material were prepared for each group: (1) V and CB; (2) V and ES; (3) V and S; (4) C and CB; (5) C and ES; and (6) C and S. Specimens were stored at 37 degrees C/24 hours and 100% humidity, polished, and initially analyzed with a surface roughness-measuring device. Next, they were fixed to the tooth-brushing device and abraded via toothbrushes, using a dentifrice slurry, performed at 250 cycles/minute with a 200 g load. The specimens were washed, dried, and analyzed identically with the same device. There was no significant interaction between material and toothbrush types. After tooth-brushing, V showed significantly higher surface roughness than C and CB and created higher surface roughness than S. No difference was observed between these toothbrushes and ES. Regardless of the toothbrush type used, resin-modified glass ionomer cement showed the highest roughness values.

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study.

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.