This article reviews the evidence for saliva diagnostics and some antibacterial concepts with potential to interfere with the caries process. It concludes that there is incomplete evidence to evaluate the role of chair-side tests and to recommend general topical applications of antibacterial agents to prevent caries lesions. However, such measures may be considered to control the disease in caries-active individuals. There is evidence that xylitol has antibacterial properties that alter the oral ecology but the clinical evidence for caries prevention is rated as fair. However, preventive programs should include as many complementary strategies as possible, especially when directed toward caries-active patients. Therefore, any antibacterial intervention should always be combined with a fluoride program, until stronger evidence for its use in caries prevention and management becomes available.