In December 2009, members of the newly redeveloped Primary Care Dentistry Research Forum (http://www.dentistryresearch.org) took part in an online vote to identify questions in day-to-day practice that they felt most needed to be answered with conclusive research. The question which received the most votes formed the subject of a critical appraisal of the relevant literature. Each month a new round of voting takes place to decide which further questions will be reviewed. Dental practitioners and dental care professionals are encouraged to take part in the voting and submit their own questions to be included in the vote by joining the website.This paper details a summary of the findings of the fourth critical appraisal. In conclusion, there is a lack of evidence relating to dentists' perceptions of prevention and its application in practice. Qualitative primary research is needed to look at UK dentists' views and attitudes relating to their understanding of prevention and its application in practice.