Economic Impact of COVID-19 Pandemic on Dental Practices in Germany: A Cross-Sectional Survey.

An observational cross-sectional survey was planned and carried out to evaluate the economic impact of the SARS-CoV-2/COVID-19 pandemic on dental practices in Germany. An online-questionnaire was developed and previously calibrated by a group consisting of experts from dentists, lawyers, and business economists (n = 21; Intra-Class-Coefficient > 0.8). It consisted of four main categories: vital statistics, professional activity and practice structure, economic impact of the COVID-19 pandemic and validation and contextualization to avoid automated filling in. The questionnaire was administered anonymously to 9732 dentists in Germany, 4434 of whom opened it and 1496 of whom fully completed it. These results were evaluated and summarized. Respondents were divided into seven German economic macro areas. Difference in proportion among questionnaire items was evaluated with χ2 test or Fisher exact test appropriately. Linear trend analysis was performed among German macro areas. Ordinal multinomial linear regression analysis was run to evaluate the association with questionnaire items with respect to a collapse and/or quarantine measures due to a positive test/infection/disease of dental personnel or an increase in average monthly costs due to the pandemic. One-third experienced a collapse or quarantine measures of the predominantly self-employed participating dentists (92%). Small practices were less affected than larger ones. Average monthly costs increased sharply in all practice structures. The findings shall help to better manage future pandemics and provide information to policy makers. As the pandemic situation is still ongoing, the medium- and long-term economic impact should be further evaluated.

Weak hydrogen bonding as a basis for concentration-dependent guest selectivity by a cyclophane host.

Crystalline inclusion complexes between the cyclophane 1 and three isomers of picoline and lutidine were grown and their properties and structures were studied by X-ray analysis, thermal gravimetry (TG), and differential scanning calorimetry (DSC). In competition experiments, the cyclophane host, which by itself is only able to form weak Cbond;H.acceptor hydrogen bonds, is able to discriminate between the different picoline or lutidine isomers, although in some cases a strong concentration dependence of the preferred isomer is observed. In the three-component experiments, inclusion of 4-picoline is strongly favored when X(4-picoline)>0.35-0.39. Very similar results were obtained in the lutidine series. The fact that 2,4-lutidine is favored when X(2,4-lutidine)>0.2 indicates that the host prefers the isomer with the methyl group in 4-position relative to the nitrogen atom. The selectivities observed can be explained based on the assignment of the inclusion complexes to different adduct classes. In the case of the picoline isomers, the preference of 4-picoline was in good agreement with the calculated lattice energies for this series. The present work also shows that caution is advisable when deducing selectivity of crystalline inclusion compounds from guest competition experiments.