During the pandemic of coronavirus disease 2019 (COVID-19), an increase in temporomandibular disorders (TMDs) was noticed in infected patients. In the present study, we aimed to assess the prevalence of TMDs during COVID-19 infection and to evaluate associated factors. An observational cross-sectional online survey was conducted in April and May 2021 in order to estimate the prevalence of TMDs in participants who were previously infected with COVID-19. A multivariable logistic regression model was carried out to explore predicting factors of TMDs during COVID-19 infection. In total, the prevalence of TMDs during the COVID-19 infection period among participants was 41.9%. High fever episodes (adjusted odds ratio {aOR}: 3.25), gastro-esophageal reflux (aOR: 2.56), and toothache (aOR: 3.83) during COVID-19 illness were found to be positive predictors of TMDs, while vitamin D deficiency was found to be a negative predictor (aOR: 0.28). Our study has highlighted a relatively high prevalence of TMDs in COVID-19-infected patients that may conclude TMDs as a possible COVID-19 symptom. Further studies are warranted to confirm the association between TMDs and COVID-19 infection and thereupon include TMDs among the known symptoms of COVID-19.

Introduction: Stainless Steel Crowns (SSC) are not easily replaced by Zirconia Prefabricated Crowns (ZPC) because of their adaptation problem and risk of fracture and loosening. Objectives: To assess and compare the trueness of milled zirconia and milled hybrid ceramic crowns designed for primary teeth restoration to a digitally designed file. Methods: The fourteen extracted primary molars were scanned using an intraoral scanner to obtain digital files of the teeth. The digital files were imported into the Design dental software (TDS) and used to design and mill zirconia and hybrid ceramic crowns using a 4-axis milling machine: 14 zirconia crowns and 14 hybrid ceramic crowns were milled. The milled crowns were fitted onto their corresponding primary molars and evaluated for trueness using Geomagic Control X Software (Control X®, Geomagic, Morrisville, NC, USA). The results were recorded in millimeters. Results: No significant difference was observed in terms of trueness between the milled zirconia crowns and the milled hybrid ceramic crowns (p>0.05). Conclusions: Computer Aided Design/Computer Aided Manufacture (CAD/CAM) technology and zirconia/ hybrid ceramic materials can be used effectively in the restoration of primary teeth. The use of the hybrid composite material in this technique provides a highly accurate, quick and esthetic solution for pediatric patients, which can improve their oral health and quality of life.