The impact of the COVID-19 pandemic on U.S. orthodontic practices in 2020.

INTRODUCTION: This study aimed to investigate the immediate impact and long-term implications of severe acute respiratory syndrome coronavirus on orthodontic practices in the United States in 2020. METHODS: A 35-item survey was developed and validated to investigate the impact of the coronavirus disease (COVID-19) pandemic on the orthodontic specialty. The survey contained 5 domains, including respondent's demographic information, COVID-19 information acquisition, practice ramifications of the COVID-19 pandemic, financial implications of the COVID-19 pandemic, and patient management strategies during the COVID-19 pandemic. This voluntary survey acquired responses from active orthodontists in the United States. Associations of demographic and practice characteristics with items related to COVID-19 were assessed using chi-square tests, with a 5% significance level. RESULTS: The survey was disseminated to 5,694 orthodontists, and 507 complete surveys were obtained (response rate of 8.9%). Respondents indicated that they obtained the most useful information regarding the COVID-19 pandemic through professional associations and internet or online news resources. However, 30% of the orthodontists believed information regarding personal financial guidelines was lacking. Most respondents identified delayed treatment progress and temporary staff layoffs as the 2 most negative ramifications of mandated office closures. Approximately 93% of practices applied for and used some sort of stimulus funding offered through the Coronavirus Aid, Relief, and Economic Security Act. Respondents indicated that the COVID-19 related office closures resulted in an average of 50% decrease in net revenue. CONCLUSIONS: The survey found that the COVID-19 pandemic had a broad and significant impact on patient care and financial aspects of U.S. orthodontic practices in 2020. Although generally accepting of the federal and state recommendations, respondents appeared to desire more guidance during the early phase of the pandemic.

The Effect of Overexpression of Lrp5 on the Temporomandibular Joint.

OBJECTIVE: The temporomandibular joint (TMJ) is a unique fibrocartilaginous joint that adapts to mechanical loading through cell signaling pathways such as the Wnt pathway. Increased expression of low-density lipoprotein receptor-related protein 5 (Lrp5), a co-receptor of the Wnt pathway, is associated with a high bone mass (HBM) phenotype. The objective of this study was to analyze the effect of overexpression of Lrp5 on the subchondral bone and cartilage of the TMJ in mice exhibiting the HBM phenotype. DESIGN: Sixteen-week-old Lrp5 knock-in transgenic mice carrying either the A214V (EXP-A) or G171V (EXP-G) missense mutations, and wildtype controls (CTRL) were included in this study. Fluorescent bone labels, calcein, alizarin complexone, and demeclocycline were injected at 3.5, 7.5, and 11.5 weeks of age, respectively. The left mandibular condyle was used to compare the subchondral bone micro-computed tomography parameters and the right TMJ was used for histological analyses. Cartilage thickness, matrix proteoglycan accumulation, and immunohistochemical localization of Lrp5 and sclerostin were compared between the groups. RESULTS: Subchondral bone volume (BV) and percent bone volume (BV/TV) were significantly increased in both EXP-A and EXP-G compared with CTRL (P < 0.05) whereas trabecular spacing (Tb.Sp) was decreased. Cartilage thickness, extracellular matrix production, and expression of Lrp5 and Sost were all increased in the experimental groups. The separation between the fluorescent bone labels indicated increased endochondral maturation between 3.5 and 7.5 weeks. CONCLUSIONS: These data demonstrate that Lrp5 overexpression leads to adaptation changes in the mandibular condylar cartilage of the TMJ to prevent cartilage degradation.