Figure 2.

Colony-forming units (CFU) of different types of bacteria at various distances from the treatment units after 1.5 and 3-h collection times. Significant contamination was detected at all distances sampled when high-speed instruments were used. Contamination was less intense during periodontal and orthodontic treatment (control) where high-speed rotating and ultrasonic instruments were not used, and was practically non-existent in rooms at rest. Means with standard deviations of total counts are shown.