Novel Substrates for Toothpaste Abrasive Particle Delivery and Stain Removal

Objectives: Toothpastes play a central role in plaque removal and oral hygiene for prevention of oral disease. However, the cleaning efficacy of toothpastes is dependent on toothbrush delivery of abrasive particles and the influence of brush design on particle delivery and action is unclear. The aim of this study was to explore the effects of novel substrates on the delivery of abrasive particles in the context of their actions on in vitro stain removal from bovine enamel.
Methods: Eight bovine enamel specimens per treatment group were prepared to 280-grit ground finish. A fresh mixture of diammonium iron (II) sulphate 6-hydrate and tannic acid was applied as successive layers (10) on enamel specimens, each of which was dried at 40 °C for 10 mins before application of the subsequent layer. Cleaning slurries comprised 15.0% (w/w) Zeodent113 silica abrasive and 1.0% (w/w) 3µm alumina abrasive particles in 0.5% (w/w) Hercules 7MF Carboxymethylcellulose plus 10% (w/w) Glycerol, respectively. Oral B P35 toothbrushes and four materials (Fleece, Foam, Scouring pad and Velcro) were used for particle delivery using a conventional brushing approach. Tooth specimen colour was measured using a calibrated spectrophotometer before staining, after the 10 layers of stain application as well as after brushing for 1,000 strokes in the Ctrl-16 brushing simulator, and stain removal efficacy calculated.
Results: Stain removal efficacy data and images of the enamel surfaces post-stain removal demonstrated that stain was completely removed from all of the tested enamel specimens after brushing with Zeodent 113 abrasive using all substrates. However, when brushing with alumina abrasive particles, only partial stain removal was detected using Oral B toothbrush and Foam, while stain was completely removed using the other substrates.
Conclusions: Substrates used for toothpaste abrasive particle delivery influence in vitro enamel stain removal and offer opportunities for development of new toothbrush design.