OBJECTIVE The aim of this study is to reduce the caries risk in cleft lip and palate (CLP) patients with multibracket appliances via a compliance-independent method. METHODS Sixty-eight CLP patients with multibracket appliances were submitted to professional tooth cleaning at 4-week intervals. After randomization, patients in group A wore a splint filled with chlorhexidine (CHX) gel (Chlorhexamed) for 15 minutes (3 x 5 min) every 12 weeks. Patients in group B were treated with CHX varnish (EC40) every 12 weeks. Fluoride varnish (Fluoridin) was applied to all teeth 4 and 8 weeks after the respective CHX treatments. Regular salivary bacteria counts (CRT) were carried out to determine therapeutic effectiveness. Initial DMFS values were compared to the final ones. RESULTS Initial findings of the salivary test and DMFS index confirmed the high caries risk. The DMFS value increased dramatically in both groups despite this systematic prophylaxis program. The bactericidal effect of both CHX preparations turned out to be markedly weaker than that described in the literature. CONCLUSIONS Though the CHX and fluoride application had a limited effect (at least in this test population), one should keep in mind that it is precisely this population that requires very intensive prophylaxis, and that no antibacterial adjuvant is more effective than CHX. However, the application interval should be individually adapted to the bacteria count.