Effect of erupting third molars on dental caries and gingival health in Finnish students

Abstract

The purpose of this study was to assess how the eruptive status of third molars relates to gingival and dental health and, in particular, to the status of the adjacent second molar. One hundred and twenty-three young adults were followed up over a 6-year period, from age 20 to age 26. The status of the second and third molars, and DMF, DMFS, DS, MS, and FS indices, periodontal condition, and salivary acidogenic bacterial counts were assessed. The 6-year DFS increase in relation to second molars was greatest in sextants with unerupted third molars. The percentage of erupting third molars that became carious or had been filled during the study period was 30%. Most new caries lesions or filled surfaces were on mesial surfaces of second molars and occlusal surfaces of third molars. The periodontal condition was best in mandibular sextants in which the third molar was missing. It is concluded that the most favourable situation for upper second molars is if the neighbouring third molar is missing by age 20.