Welch Huang

10/09/2024 · High School

Will a fluoride mouthwash used affect the number of cavities? Twenty sets of twins were used to investigate this question. One member of each set of twins used mouthwash A after each brushing, the other set used mouthwash B after brushing. After 6 months, the difference in the number of cavities of those using the mouthwash before and after was compared with the number of cavities. This study uses a. a randomized comparative experiment. b. Observational study d. a randomized complete block design. e. a matched pairs design.