An abbreviated caries clinical trial design validated over 24 months

Conventional caries trials last from 24 to 36 months. This study evaluated whether the previously established difference in efficacy between 1000- and 2500-ppm-fluoride dentifrices could be detected after 12 months. Caries was assessed by clinical visual assessment (CVA-simplified version of Dundee Selectable Threshold Method-DSTM), bitewing radiography, and Fiber Optic Transillumination (FOTI). Changes in status for individual surfaces were classified by means of pre-prepared matrices as 0 (unchanged), +1 (initiation or progression), or -1 (regression) and summed for each subject to yield an event score. Mean group event scores were calculated for each product. DSTM at the D-1 [enamel and dentin] threshold showed significant inter-group differences in mean event scores (p<0.003) and D1MFS increment (<0.007) at 12 months; these were confirmed at 24 months by traditional increment analysis (CVA & FOTI at the D-3 (dentin only) threshold + radiography, p<0.03). This study confirms the validity of an abbreviated trial protocol.