The effect of restorative dental treatment was evaluated on mutans streptococci and lactobacilli in saliva, as well as acid production by plaque bacteria. We used semiquantitative culture kits at time points up to 6 months following treatment. Changes in eating habits and oral hygiene during the study period were ruled out using a questionnaire. Mutans streptococci, lactobacilli, and acidity all had decreased significantly at 1 week after treatment. Acidity often was the first variable to return to pretreatment levels, while abundant at 6 than 3 months. Lactobacilli showed the most durable response to treatment. Restorative treatment achieves import temporary decreases in caries-associated bacteria, especially lactobacilli, without influence from potentially relevant behavioral changes. In addition, follow up examinations at relatively long intervals at least 3 month would appear most effective for dental health management.