The purpose of this quantitative research study was to explore the impact of instructional methodologies by examining the relative achievements of face-to-face and virtual instruction of dental hygiene students during and after the COVID-19 pandemic. The pandemic's lockdown precautions led educational institutions to shift from traditional face-to-face instruction to virtual formats, necessitating an investigation into the efficacy of these methods. This study addressed a notable gap in literature regarding variations in student achievement across instructional approaches. It aimed to clarify factors influencing student success in different learning environments. Using a quantitative, correlational approach, the research examined the impact of COVID-19 on academic performance within cohorts at a private, accredited higher education institution in the southeastern United States offering a dental hygiene program. The study analyzed the association between instructional methods and student success metrics, including National Board Dental Hygiene Examination (NBDHE) pass rates and Health Education Systems Incorporated (HESI) scores. Data were collected from approximately 170 students across eight cohorts. Two-Tail, Two-Sample Proportion z-tests and Chi-Square Tests of Independence were used to analyze the relationship between instructional methods and NBDHE first-time pass rates and HESI scores. Independent Sample z-tests examined the relationship between passing HESI scores and NBDHE attempts under pandemic and post-pandemic instructional methods. Results provided insight into how instructional methods affected academic achievement and offered guidance for future instructional strategies during disruptions. The theoretical framework, grounded in Knowles' andragogy, Biggs' constructive alignment, and Kolb's experiential learning theories, provided a basis for understanding how adult learners adapted and succeeded in diverse educational settings. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]