Effect of smoking on coronavirus disease susceptibility: A case-control study.

INTRODUCTION: Tobacco use has changed since the onset of the coronavirus disease (COVID-19) pandemic. The effect of smoking on COVID-19 susceptibility has not yet been determined. In this study, we aimed to assess the association between smoking and COVID-19 susceptibility. METHODS: This retrospective case-control study was conducted at the quarantine center of Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia, between April and June 2020. A total of 142 adults participated in the study, 73 of whom tested positive for COVID-19 and were matched for both sex and age with participants in the control group. Telephone interviews were conducted to assess the risk factors associated with that exposure. RESULTS: Different variables are investigated for their impact on COVID-19 infection susceptibility. The current study's findings indicated that smokers comprised only 27.5% (n=39) of the participants. There was no association between the COVID-19 swab results and smoking status (χ2=1.857; p=0.395). Furthermore, there was no significant association between any of the smoking parameters and susceptibility to COVID-19, except for the smoking period (t= -2.105, p=0.041). The odds of having a positive swab result among cigarette smokers were lower than those among pipe, waterpipe, and electronic cigarette smokers (OR=0.600; p=0.394). An association was also observed between COVID-19-positive swab results and contact with an individual with COVID-19 or respiratory disease (χ2=79.270 and χ2=18.929, respectively, p≤0.001). CONCLUSIONS: This study revealed no association between smoking status and COVID-19 swab test results. Further research with a bigger sample size is suggested to confirm the relationship between smoking and COVID-19 susceptibility.

Preparation of Nano-Apatite Grafted Glass-Fiber-Reinforced Composites for Orthodontic Application: Mechanical and In Vitro Biofilm Analysis.

This study aimed to fabricate nano-hydroxyapatite (nHA) grafted/non-grafted E-glass-fiber-based (nHA/EG) and E-glass fiber (EG) orthodontic retainers and to compare their properties with commercially available retainers. Stainless-steel (SS) retainers and everStick Ortho (EST) were used as control groups. The retainers were evaluated with Raman spectroscopy and bonded to bovine teeth. The samples were fatigued under cyclic loading (120,000 cycles) followed by static load testing. The failure behavior was evaluated under an optical microscope and scanning electron microscope. The strain growth on the orthodontic retainers was assessed (48h and 168h) by an adhesion test using Staphylococcus aureus and Candida albicans. The characteristic peaks of resin and glass fibers were observed, and the debonding force results showed a significant difference among all of the groups. SS retainers showed the highest bonding force, whereas nHA/EG retainers showed a non-significant difference from EG and EST retainers. SS retainers' failure mode occurred mainly at the retainer-composite interface, while breakage occurred in glass-fiber-based retainers. The strains' adhesion to EST and EG was reduced with time. However, it was increased with nHA/EG. Fabrication of nHA/EG retainers was successfully achieved and showed better debonding force compared to other glass-fiber-based groups, whereas non-linear behavior was observed for the strains' adhesion.

The Influence of Physical Activity on COVID-19 Prevention Among Quarantined Individuals: A Case-Control Study.

BACKGROUND: Physical activity is a known preventive measure for many worldwide public health issues. The purpose of this study is to assess the association between physical activity and the susceptibility to COVID-19 infection. PATIENTS AND METHODS: This was a retrospective matched case-control study involving adult participants quarantined with IAU, Dammam, Saudi Arabia. The total randomized sample of study participants were 142, in which 73 of them were tested positive for COVID-19 test and matched for both age and sex with their respective healthy controls who tested negative for COVID-19 test to determine the risk associated with that exposure. RESULTS: Several variables are assessed regarding their influence on the susceptibility of COVID-19 infection. Exactly half indicated that they were physically active (n = 71). Physical activity did not show any significant association with COVID-19 contraction (x 2= 0.254, P= 0.614) nor self-rated level of physical activity (x 2= 0.122, P= 0.727). Less than half of the participants who had contact with a COVID-19 patient within 14 days of admission to quarantine appeared to have a significantly higher incidence of positive COVID-19 swab results compared to those who did not (x 2= 27.121, P= <0.001). While third of the participants who indicated that they have had a contact with someone who have Respiratory symptoms or fever within 14 days before admission were tested positive for COVID-19. Participants with lower educational degrees are more likely to be infected with COVID-19. While the rest of the demographic variables appear to be not significantly related to the likelihood of being COVID-19 infected, these include gender, marital status, employment status, age, and BMI. CONCLUSION: The present study showed no significant association between physical activity and susceptibility to COVID-19 infection. We recommend a larger sample size to further clarify the relationship between other variables and susceptibility of COVID-19.

Effect of Steam Heat Sterilization on the Accuracy of 3D Printed Surgical Guides.

INTRODUCTION: Steam heat sterilization could be one of the factors that affects the dimensional accuracy of surgical guides, leading to an error during guided implant surgery. OBJECTIVE: The purpose of this study was to investigate the effect of steam heat sterilization on the dimensional changes of surgical guides. MATERIALS AND METHODS: A total of 27 surgical guides, which were made by either Formlabs printer (Formlabs Inc., Somerville, MA) or Simplant (DENTSPLY Implants NV, Hasselt, Belgium), were scanned using an intraoral scanner before and after sterilization. The dimensional changes at the center of the implant sleeves were analyzed using the computer-aided design interactive software for 65 implant sites before and after steam heat sterilization at 121°C for 20 minutes. RESULTS: There was no significant difference between the mean x, y, and z axes of the center of the sleeves when measured before and after sterilization (P values were 0.37, 0.24, and 0.29, respectively). Nonparametric analysis showed no significant difference between the mean deviations of either surgical guide (P = 0.908). CONCLUSION: Steam heat sterilization has a nonsignificant effect on the dimensional changes of the tested surgical guides.