Novel Artificial Biofilm Equivalent for Training Teeth

Objectives: Extracellular matrix is a large part of the dental biofilm and promotes adhesion. To simulate dental biofilm adhesion and abrasion resistance against tooth brushing in research and education, an Artificial Biofilm Equivalent (ABE) was developed to be applied to training teeth. It contains a mixture of chitosan (ChS) and methylcellulose (MC).
Methods: 16 molar training teeth (cellulose reinforced melamine, KAVO) were embedded in polymethylmethacrylate (Palapress) cylinders and cut at the height of their anatomic equators. Smoothing the cut surface with 1000 grit sandpaper revealed a roughness similar to the training tooth surfaces upon delivery (Ra=0.4µm). Two different ABEs were prepared: 1.0g ChS + 1.0g MC (ABE1) and 0.4g ChS + 1.6g MC (ABE2) were diluted each in 100ml of 2% acetic acid. 2.0g medical ground charcoal (Detrade) was added to both for dyeing. Eight cut training tooth surfaces were coated with 1ml of each solution, dried at 40°C (3h), neutralized in 1 molar NaOH (10min) for solidification and rinsed in distilled water. The formed ABEs were tested for abrasion resistance with a tooth brushing simulator (soft tooth brushes, load 3N, toothpaste slurry). After 3, 6, 9, and 12 brushing cycles, each coated tooth surface underwent standardized photography. Percentages of remaining ABE were assessed using computer assisted planimetric measurements and means (n=8) calculated.
Results: Remaining ABE1 (1.0g ChS + 1.0g MC) stayed above 95% between 3 and 12 brushing cycles. Remaining ABE2 (0.4g ChS + 1.6g MC) was 95% (SD 1.0%) after 3 cycles, 64% (SD 15%) after 6 cycles, 15% (SD 10%) after 9 cycles and 7% (SD 6%) after 12 brushing cycles.
Conclusions: ABE1 strongly adhered to the training teeth. ABE2 abraded continuously with increasing number of brushing cycles. The novel ABE seems suitable to simulate abrasion resistance of natural dental biofilm. Abrasion resistance can be adjusted by shifting the ChS/MC ratio.