ABSTRACT
Due to COVID-19, universities across Canada were forced to undergo a transition from classroom-based face-to-face learning and invigilated assessments to online-based learning and non-invigilated assessments. This study attempts to empirically measure the impact of COVID-19 on students' marks from eleven science, technology, engineering, and mathematics (STEM) courses using a Bayesian linear mixed effects model fitted to longitudinal data. The Bayesian linear mixed effects model is designed for this application which allows student-specific error variances to vary. The novel Bayesian missing value imputation method is flexible which seamlessly generates missing values given complete data. We observed an increase in overall average marks for the courses requiring lower-level cognitive skills according to Bloom's Taxonomy and a decrease in marks for the courses requiring higher-level cognitive skills, where larger changes in marks were observed for the underachieving students. About half of the disengaged students who did not participate in any course assessments after the transition to online delivery were in special support.
ABSTRACT
STATEMENT OF THE PROBLEM: Melanin pigmentation of the gingiva is a crucial esthetic problem. A variety of methods have been used for gingival depigmentation. PURPOSE: The purpose of this study was to compare the results of two treatment modalities: scalpel technique and cryotherapy with liquid nitrogen in treatment of gingival pigmentation. MATERIALS AND METHOD: Twenty patients with chief complaint of gingival pigmentation participated in our study. 10 patients were treated with cryotherapy and remaining 10 participants were undergone the scalpel technique surgery. We evaluated acquiescence and comfort of the patients, degree of depigmentation, based on the area of pigmentation shown by gridlines option in Microsoft Paint software, and the presence or absence of gingival recession before and one month after treatment. Data was analyzed using Mann-Whitney and Chi-Square tests. A significance level of p≤ 0.05 was adopted. RESULTS: Mean value and standard deviation of depigmentation for group A and group B was 96.17±2.51 and 95±2.48, respectively. The difference was not statistically significant (p= 0.225). There was no association between the treatment modality and the gingival recession (p= 0.303) or the treatment modality and the patient satisfaction (p= 0.346). No significant difference was found between gingival recession measures before and after the operation in the two treatment modalities. CONCLUSION: Surgical blade and cryosurgery with liquid nitrogen had no significant difference in treatment of physiologic gingival pigmentation. Both Techniques are acceptable in the treatment of gingival pigmentation.
