EFFECT OF ERUPTING 3RD MOLARS ON DENTAL-CARIES AND GINGIVAL HEALTH INFINNISH STUDENTS

The purpose of this study was to assess how the eruptive status of thi rd 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 ag e 26. The status of the second and third molars, and DMF, DMFS, DS, MS , and FS indices, periodontal condition, and salivary acidogenic bacte rial counts were assessed. The 6-year DFS increase in relation to seco nd molars was greatest in sextants with unerupted third molars. The pe rcentage of erupting third molars that became carious or had been fill ed during the study period was 30%. Most new caries lesions or filled surfaces were on mesial surfaces of second molars and occlusal surface s of third molars. The periodontal condition was best in mandibular se xtants in which the third molar was missing. It is concluded that the most favourable situation for upper second molars is if the neighbouri ng third molar is missing by age 20.