1 Select the most appropriate study design for investigating the topics given below.

Options:

(a) Case- control study

(b) Cohort study

(c) Cross- sectional study

(d) Crossover trial

(i) Wisdom teeth removal in adults during their twenties and thirties.

(ii) The proportion of adults in Glasgow registered with a dentist.

(iii) The effectiveness of dental fl oss and dental tape in reducing the development of plaque.

(iv) The impact of smoking on the discoloration of teeth using patients arriving for their fi rst appointment following registration at a practice.