A longitudinal epidemiological study on dental plaque and the development of dental caries--interim results after two years.

1. During the two-year period, caries developed at 20% of the target premolar sites. The attack rate for these surfaces was similar in the plaque panel and the other subjects in the study. 2. The microbial composition of plaque samples from caries-free sites and from carious sites before and after radiographic detection of lesions was broadly similar. 3. Numerical domination of particular sites by S mutans before detection of caries can occur, but has only been observed so far in 2 of 15 sites. 4. Pooled date from sites which have developed lesions indicate a rise in the isolation frequency and mean numbers of S. mutans after detection of caries. This trend was particularly obvious in the one subject who developed bilateral lesions by the second examination and in three of four sites where caries was detected at the fourth examination. Similar observations have been made with lactobacilli. 5. In two of 15 instances no isolations of S mutans were made from sites which developed caries. 6. To date, no single species appears to be uniquely associated with the onset of dental caries.

A study of intra-examiner error associated with recording of radiographic caries at different diagnostic levels.

Pairs of posterior bitewing radiographs of forty children 13-15 years of age at the third and fourth examinations of three-year clinical trials were assessed by one examiner for primary caries. Duplicate assessments were carried out in independent sessions, recording simultaneously absence/presence of caries and caries degree, and in the same way for three different diagnostic levels recording only absence/presence of caries. Caries diagnostic inconsistency rate (D.I.R.) in per cent was always lower than 34 and usually below 20; a finding which is in agreement with previously published results. No preference could be expressed for any particular diagnostic level on the basis of the primary caries scores, but recording only relatively advanced lesions tended to give most favourable results for DFS increment scores. The recording of both absence/presence of caries and caries degree simultaneously had a small, but not consistently adverse effect on the D.I.R. and reliability coefficient. As there was no marked difference in examiner error associated with two of the demarcation lines used for recording of caries degree, i.e. half way through enamel and the A.D.J., the scoring codes described here may be suitable for studies of radiographic caries progression.

Progression of approximal caries in relation to radiographic scoring codes. A pilot study.

Forty pairs of posterior bitewing radiographs taken at the third and fourth annual examinations of three-year clinical trials were assessed twice for caries by one examiner in independent recording sessions. Three or four degrees of caries were recorded in order to determine how different scales of measurement affected aproximal caries progression patterns. The use of one degree of enamel caries, instead of two reduced by about half the percentage of lesions which appeared to have progressed during one year. Most lesions seemed to remain unchanged during the 12 months of observation and those which advanced usually progressed across one demarcation line. Reversals of caries diagnosis and regression of lesions to a lower degree of caries contributed least to the pattern of change between the two examinations. It is concluded that the radiographic scoring codes with two degrees of enamel caries give a better picture of caries progression than those with only one.