Self-perceived mouthfeel and physico-chemical surface effects after chewing gums containing sorbitol and Magnolia bark extract

The European Food Safety Authority recognizes the contribution of sugar-free chewing gum to oral health through increased salivation, clearance of food debris, and neutralization of biofilm pH. Magnolia bark extract is a gum additive shown to reduce the prevalence of bad-breath bacteria but its effects on self-perceived mouthfeel are unknown. This paper aims to relate the effects of sorbitol-containing chewing gum, with and without Magnolia bark extract, on tooth-surface hydrophobicity and salivary-film composition with self-perceived mouthfeel. In a crossover clinical trial, volunteers chewed sorbitol-containing gum, with or without Magnolia bark extract added, three times daily during a 4-wk time period. A subset of volunteers also chewed Parafilm as a mastication control. Oral moistness and tooth smoothness were assessed using questionnaires, and intra-oral water-contact angles were measured before, immediately after, and 60min after, chewing. Simultaneously, saliva samples were collected, placed on glass slides, and the compositions of the adsorbed film were measured using X-ray photoelectron spectroscopy. Chewing of gum, regardless of whether or not it contained Magnolia bark extract, improved self-perceived mouthfeel up to 60min, concurrent with a more hydrophilic tooth surface and an increased amount of O-1s electrons bound at 532.6 eV in salivary films. Chewing of Parafilm affected neither tooth-surface hydrophobicity nor salivary-film composition. Accordingly, adsorption of sorbitol, rather than the presence of Magnolia bark extract or increased salivation, is responsible for improved self-perceived mouthfeel