Outcome of Different Processing Methods on Mechanical and Physicochemical Properties of Human Dentin as a Potential Natural Scaffold

Dentin has been considered a promising scaffold for bone regeneration. This study investigated the effects of two different demineralization and deproteinization methods on the mechanical and physicochemical properties of dentin as a potential scaffold for tissue engineering approaches. Eighty dentin discs were divided into five groups according to the treatment process: control (C), no treatment; DEM1, complete demineralization with HCl; DEM2, partial demineralization with different concentrations of EDTA; DEP1, complete deproteinization using NaOCl solution; and DEP2, partial deproteinization by boiling water. The treated dentin discs were characterized using ATR-FTIR and SEM. The compressive strength, elastic modulus, and microhardness values of all C and treated samples were measured. They were analyzed using one-way ANOVA, Kruskal-Wallis, and Weibull analysis. FTIR showed significantly reduced mineral/matrix ratio in demineralized groups (DEM1 and 2) (p \u3c 0.001), while increase of mineral/matrix ratio in DEP1 was not significant (p = 0.31). SEM observations revealed open dentinal tubules in DEM1 group and lower amounts in the other groups. The C showed the highest compressive strength (78.18 ± 16.19 MPa), and the DEM1 showed the lowest (0.84 ± 0.32 MPa). The treated groups showed lower Weibull moduli (m), when compared with the C group. The DEP2 (642 ± 318.9) and DEM1 (2.9 ± 1.37) groups showed the highest and lowest modulus of elasticity, respectively. DEM1 showed the least hardness values (10.27 ± 3.09) compared to the other groups (p \u3c 0.001). Based on the results, the DEM1 showed confirmed demineralization and lowest mechanical properties. The highest mechanical properties belonged to DEM2 and DEP2 groups which both were partially treated. Depending on the purpose of the regeneration, the dentin processing method can be selected. Whenever the high mechanical properties are more important in scaffold selection, DEM2 and DEP2 are the best choices

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.The aim of this study was to inform vaccination prioritization by modelling the impact of vaccination on elective inpatient surgery. The study found that patients aged at least 70 years needing elective surgery should be prioritized alongside other high-risk groups during early vaccination programmes. Once vaccines are rolled out to younger populations, prioritizing surgical patients is advantageous