Biofilm volume cultured for 2 days on bonding agents. (a) Live biofilm volume; (b) dead biofilm volume (mean±s.d.; n=6). Seven bonding agents were tested: SBMP control, SBMP+DMAPM (CL3), SBMP+DMAHM (CL6), SBMP+DMANM (CL9), SBMP+DMADDM (CL12), SBMP+DMAHDM (CL16) and SBMP+DMAODM (CL18). In each plot, values with dissimilar letters are significantly different from each other (P<0.05). CL, chain length; 3D, three-dimensional; DMADDM, dimethylaminododecyl methacrylate; DMAHDM, dimethylaminohexadecyl methacrylate; DMAHM, dimethylaminohexyl methacrylate; DMANM, dimethylaminononyl methacrylate; DMAODM, dimethylaminooctadecyl methacrylate; DMAPM, dimethylaminopropyl methacrylate; SBMP, Scotchbond multi-purpose bonding agent; s.d., standard deviation.