COVID-19 infection rates and mitigation strategies in orthodontic practices.

BACKGROUND: COVID-19 has impacted and increased risks for all populations, including orthodontic patients and providers. It also changes the practice management and infection control landscape in the practices. This study aimed to investigate the COVID-19 infection and vaccination status of orthodontic providers and mitigation approaches in orthodontic practices in the United States during 2021. METHODS: A validated 50-question research electronic data capture (REDCap) browser-based questionnaire was distributed to 12,393 orthodontists and pediatric dentists who reported actively providing orthodontic treatment. Questions were designed to collect demographic data of respondents, evaluate the COVID-19 mitigation approaches, and evaluate the history of COVID-19 infection and vaccination status of the orthodontic providers. Associations of demographic and the COVID-19 mitigation approaches were assessed using chi-square tests at the significance level of 0.05. RESULTS: Four hundred fifty-seven returned the survey (response rate 3.69%) for analysis. Most respondents were vaccinated, and increased infection control measures in response to the pandemic. Half of the respondents practiced teledentistry and switched to digital impression systems. Two-thirds reported difficulties in attaining PPEs due to the increased cost and scarcity of PPEs. About 6% of respondents reported a history of COVID-19 infection, and 68.9% of their staff had COVID-19 infection. Statistically significant associations were found between increased practice experience with difficulties in acquiring PPE (p = .010). There were no significant associations between races of respondents, geographic location, and years of practicing when cross-tabulated with vaccination status or COVID-19 infection rate (p > .05). CONCLUSION: Increased infection control strategies were employed in almost all orthodontic practices in addition to existing universal precaution. Most of the orthodontic providers and their staff members were vaccinated. While staff's infection rates were an issue, doctors' infection rates remained low.

Roles of TroA and TroR in Metalloregulated Growth and Gene Expression in Treponema denticola.

The availability of divalent metal cations required as cofactors for microbial metabolism is severely limited in the host environment. Bacteria have evolved highly regulated uptake systems to maintain essential metal homeostasis to meet cellular demands while preventing toxicity. The Tro operon (troABCDR), present in all sequenced Treponema spp., is a member of a highly conserved family of ATP-binding cassette transporters involved in metal cation uptake whose expression is controlled by TroR, a DtxR-like cation-responsive regulatory protein. Transcription of troA responds to divalent manganese and iron (T. denticola) or manganese and zinc (T. pallidum), and metal-dependent TroR binding to the troA promoter represses troA transcription. We report here the construction and complementation of defined T. denticola ΔtroR and ΔtroA strains to characterize (i) the role of TroA in metal-dependent T. denticola growth and (ii) the role of TroR in T. denticola gene expression. We show that TroA expression is required for T. denticola growth under iron- and manganese-limited conditions. Furthermore, TroR is required for the transcriptional regulation of troA in response to iron or manganese, and deletion of troR results in significant differential expression of more than 800 T. denticola genes in addition to troA These results suggest that (i) TroA-mediated cation uptake is important in metal homeostasis in vitro and may be important for Treponema survival in the host environment and (ii) the absence of TroR results in significant dysregulation of nearly one-third of the T. denticola genome. These effects may be direct (as with troA) or indirect due to dysregulation of metal homeostasis.IMPORTANCETreponema denticola is one of numerous host-associated spirochetes, a group including commensals, pathobionts, and at least one frank pathogen. While most T. denticola research concerns its role in periodontitis, its relative tractability for growth and genetic manipulation make it a useful model for studying Treponema physiology, metabolism, and host-microbe interactions. Metal micronutrient acquisition and homeostasis are highly regulated both in microbial cells and by host innate defense mechanisms that severely limit metal cation bioavailability. Here, we characterized the T. denticolatroABCDR operon, the role of TroA-mediated iron and manganese uptake in growth, and the effects of TroR on global gene expression. This study contributes to our understanding of the mechanisms involved in cellular metal homeostasis required for survival in the host environment.