Caries incidence rates in Swedish adolescents and young adults with particular reference to adjacent approximal tooth...

The objective was to assess the dependence of the caries status of the adjacent approximal surface on the incidence of approximal caries.

At baseline, the material consisted of a cohort of 536 Swedish children. The individuals were followed through annual bitewing radiographs from the age of 11-13 to 21-22 years. A radiographic scoring system was used to assess the caries status of the surfaces: scores 0 and 1 = sound surface to score 4 = caries in the outer half of the dentine. A model was used to calculate the dependence of the caries status of adjacent approximal tooth surfaces. The unit of analysis was a pair of adjacent approximal surfaces and in all, 12 pairs of posterior approximal surfaces were analysed.

The individual caries rates of the 24 posterior approximal surfaces ranged from 1.3 to 8.3 new caries lesions per 100 tooth surface-years. The caries rate of an approximal tooth surface depended on the caries status of the adjacent surface: a sound surface next to a sound surface had a relatively small risk of developing caries, while the risk increased 1.6-32.3 times if the adjacent surface was in a caries state as judged radiographically. The distal surface of the first molar developed caries more often than the mesial surface of the second molar.

The caries rate of an approximal tooth surface was 1.6-32.3 times higher if the adjacent surface was in a caries state compared to when the latter was sound.