Morphology of in Vivo Salivary Pellicles after Exposure to Dentifrices

Salivary pellicles are frequently exposed to dentifrices with an impact on their thickness and surface roughness. One can speculate that both properties of salivary pellicles are likely important for oral biological properties as well as intraoral peception of cleanliness. Objectives: The aim of this study is to compare the pellicle composition and morphology after exposure to a dentifrice containing fluoride and sodium lauryl sulphate (Crest regular, CR) and a dentifrice supplemented with hexametaphosphate (Crest Dual Action Whitening, CDAW). Methods: Enamel blocks were fixed in the flanges of dentures and worn by two denture wearers up to 3 days. Daily oral hygiene on one side of the mouth was established by flushing with a dentifrice slurry, while the other side was brushed. Immediately after the experimental period, samples were removed and analysed by XPS (X-ray photoelectron spectroscopy) for pellicle thickness and AFM (Atomic force microscopy) for surface roughness. In separate studies, mouth feel was evaluated on a scale from -2 (bad) to 2(good) in ten volunteers with a full dentition at various times during the day after one weeks use of dentifrices. Results: On average, the use of CDAW yielded smooth pellicle surfaces with a roughness of around 35 nm, which was three times smoother than after use of CR. Moreover, in vivo pellicles, after preparation for XPS, had a thickness of 4.0 nm after CR, while after use of CDAW the thickness had decreased to 3.2 nm. These changes were concurrent with a strongly superior mouth feel after the use of CDAW (38.9 % above neutral throughout day) as compared with volunteers using CR (19.9 %). Conclusions: The roughness and thickness of salivary pellicles is influenced by routine hygiene and oral products including hexametaphosphate containing dentifrices. Mouth perception anecdotally appears also to be influenced by pellicle thickness and structure.