Influence of Windowing and Evaluation of Metal Artifact Reduction Algorithm on Five Different Restorative Materials by Using Different Cone Beam Computed Tomography (CBCT) Scanners: A CBCT Study.

OBJECTIVES: To assess the influence of windowing, and to evaluate, and compare the effect of the metal artifact reduction (MAR) and non-metal artifact reduction (non-MAR) algorithms on different high-density restorative dental materials using different cone beam computed tomography (CBCT) devices. MATERIAL AND METHOD: Height and diameter of all cylindrical shape metals including amalgam, cobalt-chromium, composite, gutta-percha, and titanium were measured using a digital caliper device. Polymethylmethacrylate block and arch phantom with a cylindrical-shaped perforation containing five different metals were submitted to tomographic acquisition with six different cone beam computed tomographic devices in small fields of view with their MAR enabled and disabled. Windowing was done using ITK-SNAP software (3.8.2) which was used as a contrast medial tool for window level and window width. The data was analyzed for probability distribution using the Kolmogorov-Smirnov test, where a p-value of <0.05 indicated that the data were not normally distributed. The comparison of length and width was done using the Wilcoxon sign rank test. Comparison of categorical variables was done using the Chi-square test where a p-value of <0.05 was considered statistically significant. RESULTS: Length and width of all these metals measured using MAR and non-MAR CBCT were found to be statistically non-significant (p-value of >0.05). MAR algorithm significantly reduces metals artifact produced by high-density restorative materials (p-value of <0.05). CONCLUSION: Amalgam and cobalt-chromium produced more artifacts while composite and gutta-percha did not produce enough artifacts to be reduced by the MAR algorithm. Large window width and high window level would be beneficial to reduce the metal artifact.

Facial Nerve Palsy as Complication in COVID-19 Associated Mucormycosis: A Case Series.

Mucormycosis is an opportunistic fungal infection indicating a high mortality rate. Among six varieties of involved sites, rhino cerebral mucormycosis (RCM) is not the most uncommon. During the COVID-19 pandemic, with the increase, in predisposing conditions incidence rate of mucormycosis progressed. For aggressive treatment, an early diagnosis can be armored to reduce morbidity and mortality. Clinically RCM poses non-specific symptoms and signs delaying diagnosis. This is associated with orbital cellulitis and sinusitis, one-sided headache behind the eye, diplopia, blurring of visions, nasal congestion, rhinorrhea, epistaxis, nasal hypoesthesia, facial pain and numbness, and a history of black nasal discharge. Not commonly the complications of cranial nerve involvement have been reported. In the present case series, three presentations of facial nerve palsy in COVID-19 associated with mucormycosis are added to the literature database.