Molar position associated with a missing opposed and/or adjacent tooth: a follow up study in women

The purpose of the study was to assess (i) the degree of overeruption of molars lacking opposed teeth and (ii) the inclination of molars with a mesial edentulous space and alsoto study (iii) changes during a 12 year period. The subject sample originated from the prospective population study of women in Gothenburg, Sweden where scanned panoramic radiographs taken with an interval of 12 years were analysed. Tipping as well as overeruption were scored on the two images according to a five-level scale. Sixty-seven subjects fulfilled the inclusion criteria at baseline and were referred to as "the non-extraction group". Further 35 subjects had lost the opposed and/or the adjacent tooth/teeth during the 12-year follow-up period: "the extraction-group". These groups were studied separately and a comparison between these groups was performed. The prevalence of molars tipped more than 15 degrees at baseline was 17.1% in the upper jaw and 44.3 % in the lower jaw, in the non-extraction group. At baseline overeruption was seen in 25 % of the unopposed upper molars and none of lower molars in the non-extraction group. The prevalence of tipping and overeruption was statistical significant less in the extraction group (P<0.01), than in the non-extraction group at baseline, but at follow-up no statistical significant group differences existed.

The prevalence of tipped molars facing a mesial edentulous space and overerupted unopposed molars increased in adults during the 12-year period but the changes were small. Overeruption and tipping is most pronounced immediately after extractions.