Impact of particle morphology on abrasion, polishing and stain removal efficacy in a tooth cleaning model system

Toothbrushing with toothpaste is used for daily maintenance of oral hygiene, and aims to remove food debris, the dental plaque biofilm and dental stains from tooth surfaces. However, toothpastes can also cause tooth abrasion as different particle morphologies are known to exert differential cleaning and abrasivity. Consequently, silica and alumina particles with spherical and angular morphologies, at comparable size ranges and concentrations, were used to brush polished, partially roughened or stained bovine enamel specimens and their impact on tooth abrasion, surface polishing and stain removal in vitro, was determined. Spherical silica gel particles at concentrations as low as 0.5% (w/w) achieved greater dental stain removal and higher surface polishing compared with 15% (w/w) standard abrasive silica without producing significant increases in enamel wear. Comparable results were also found for alumina abrasive particles, whilst spherical alumina particles at concentrations as low as 0.25% (w/w) showed greater stain removal compared with 1% (w/w) angular alumina particles. Both particles achieved similar surface polishing and produced less enamel wear. These findings are important in underpinning the development of dentifrices which aim to achieve optimal cleaning whilst minimising dental hard tissue damage.