4.9.1. Planktonic

Testing of *Streptococcus mutans* UA-159 (ATCC ® 700610) planktonic forms was according to described methods [47,58]. Briefly, bacterial cultures with an optical density of 1.2–1.3 at 600 nm (Unico ® 1200 Spectrophotometer, United Products & Instruments, Inc., Dayton, NJ, USA) were diluted and seeded onto copolymer disks at a density of ~3 × 10<sup>7</sup> CFU/disk. Another disk was placed atop to maximize contact. Aftera2h incubation (37 ◦C, 5% CO2) the samples were placed in 1 mL of Todd Hewitt broth, rigorously mixed, and utilized to prepare a 10-fold dilution series. A 100 μL aliquot of the resulting suspensions were spread onto the surface of THB agar plates. After incubation (~20 h at 37 ◦C, 5% CO2), colony-forming units were enumerated using an IncuCount Colony Counter (Revolutionary Science, Shafer, MN, USA). UPE resin disks and HemCon ® Dental Dressing (HemCon Medical Technologies, Inc., Portland, OR, USA) were used as negative and positive controls, respectively. Around 30 to 300 CFU per spread plate was the range considered countable. Notwithstanding, agar plates streaked with neat solutions of some groups yielded less than the lower limit of detection. Such data were reported as less than the limit of quantification. The number of CFU/mL was calculated as CFU number/(volume plated × dilution factor). Mean counts were obtained from five independently tested copolymer disk sandwiches.
