title: Surface thermodynamic homeostasis of salivary conditioning films through polar-apolar layering.
abstract: Salivary conditioning films (SCFs) form on all surfaces exposed to the oral cavity and control diverse oral surface phenomena. Oral chemotherapeutics and dietary components present perturbations to SCFs. Here we determine the surface energetics of SCFs through contact angle measurements with various liquids on SCFs following perturbations with a variety of chemotherapeutics as well as after renewed SCF formation. Sixteen-hour SCFs on polished enamel surfaces were treated with a variety of chemotherapeutics, including toothpastes and mouthrinses. After treatment with chemotherapeutics, a SCF was applied again for 3 h. Contact angles with four different liquids on untreated and treated SCF-coated enamel surfaces were measured and surface free energies were calculated. Perturbations either caused the SCF to become more polar or more apolar, but in all cases, renewed SCF formation compensated these changes. Thus, a polar SCF attracts different salivary proteins or adsorbs proteins in a different conformation to create a more apolar SCF surface after renewed SCF formation and vice versa for apolar SCFs. This polar-apolar layering in SCF formation presents a powerful mechanism in the oral cavity to maintain surface thermodynamic homeostasis--defining oral surface properties within a narrow, biological range and influencing chemotherapeutic strategies. Surface chemical changes brought about by dietary or chemotherapeutic perturbations to SCFs make it more polar or apolar, but new SCFs are rapidly formed compensating for changes in surface energetics.
authors.affiliation: Department of Biomedical Engineering, University Medical Center Groningen, Antonius Deusinglaan 1, 9713, AV Groningen, The Netherlands. h.c.van.der.mei@med.umcg.nl
authors.forename: Henny C
authors.initials: HC
authors.lastname: van der Mei
authors.forename: Don J
authors.initials: DJ
authors.lastname: White
authors.forename: Jelly
authors.initials: J
authors.lastname: Atema-Smit
authors.forename: Gésinda I
authors.initials: GI
authors.lastname: Geertsema-Doornbusch
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Busscher
mesh_terms: D000328:Adult; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry; D002417:Cattle; D002594:Cetylpyridinium / Q000737:chemistry; D003743:Dental Enamel / Q000648:ultrastructure; D044622:Dental Pellicle / Q000737:chemistry; D005260:Female; D006706:Homeostasis; D006801:Humans; D008297:Male; D009067:Mouthwashes / Q000737:chemistry; D020442:Poloxamer / Q000737:chemistry; D012471:Salivary Proteins and Peptides / Q000737:chemistry*; D017693:Sodium Bicarbonate / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012969:Sodium Fluoride / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014002:Tin Fluorides / Q000737:chemistry; D014100:Toothpastes / Q000737:chemistry; D014260:Triclosan / Q000737:chemistry; D017155:Wettability
chemical_list: D000891:Anti-Infective Agents, Local; D002327:Cariostatic Agents; D009067:Mouthwashes; D012471:Salivary Proteins and Peptides; D013501:Surface-Active Agents; D014002:Tin Fluorides; D014100:Toothpastes; D020442:Poloxamer; D012967:Sodium Dodecyl Sulfate; D014260:Triclosan; D017693:Sodium Bicarbonate; D012969:Sodium Fluoride; D002594:Cetylpyridinium