DO CARIES EXPLORERS TRANSMIT INFECTIONS WITHIN PERSONS - AN EVALUATION OF 2ND MOLAR CARIES ONSETS

Dental caries explorers may become contaminated during routine caries examinations with pathogenic organisms and thereby potentially transmi t infections from one tooth to another within a patient. The purpose o f this study was to test the hypothesis that the contamination status of explorers influenced the caries risk of second molars. Two explorer contamination statuses were defined: (1) contamination status 1 - exp lorers which had probed a carious molar just prior to examining the se cond molar versus explorers which had probed a sound molar prior to ex amining the second molar, and (2) contamination status 2 - sterile exp lorers versus explorers which had probed several teeth. Caries examina tions were performed by 4 dentists on a cohort of 4th grade students i n Belize City. The examination dates and sample sizes (n) were: Septem ber-October 1989 (n = 1,277), January 1991 (n = 1,111), and January 19 92 (n = 961), and January-February 1993 (n = 861). Within this cohort, there were 221 subjects who (1) had at least one pit and fissure cari ous onset on a caries-free second molar, (2) had no evidence of dental treatments, and (3) were examined by the same examiner during the ent ire study. After adjusting for confounding variables, the examination of a second molar with a dental caries explorer in either contaminatio n status 1 or 2 had no substantial effect on the caries risk (rate rat io 0.95, 95% confidence interval: 0.77-1.18, and rate ratio 1.18, 95% confidence interval: 0.89-1.56, respectively). Ifa true rate ratio of 1.7 or greater was associated with the contamination status 1 and 2, t hese analyses had more than 99 and 80% probability of detecting it, re spectively. Conclusions: Examining a sound second molar with a contami nated dental explorer either does not affect the caries risk, or resul ts in such a small increase in caries risk that it can only be reliabl y identified in studies where the exposure of sound teeth to contamina ted dental explorers is randomized.