Lubricated tissue-friction modification from peroxide-based tooth “whitening” treatment of as-prepared vs. saline-extracted composite restorative materials
Penman, Todd M.
MetadataShow full item record
There is concern that increased incidence of oral keratitis might result from bleach-induced surface modifications to composite resin restorations, including possible increased friction against oral mucosa. This investigation employed a laboratory test system previously successful in evaluating intra-oral lubricity of xerostomia-relief formulations and assessing friction of contact lenses against surrogate mucosal tissues. Coefficients of Friction (CoF) were measured for duplicate dome-shaped specimens of 14 widely used restorative composite resins, as-prepared, saline-extracted, and after standard treatment with 9-10%-H 2 O 2 tooth-whitening gel strips, articulated against saline- vs. saliva-lubricated preserved bovine pericardium. All composite specimens had been identically cast and cured, and pre-characterized by Multiple Attenuated Internal Reflection Infrared Spectroscopy for surface compositional analyses, followed by Comprehensive Contact Angle analyses for outermost atomic constitutions and surface energy differences that might correlate with CoF results. CoF control data were acquired for intact enamel surfaces of 10 extracted human teeth. Composite specimen light reflectance values before and after "whitening" agent treatments were taken over the range from 360 to 740 nanometers and with specific photopic green, red, and blue filters to document changes in surface optical properties due to the chemical treatment. Post-whitening contact angle data also were recorded, as were Scanning Electron Microscopic images of a specimen's initial and final surface textures. Composite-on-tissue friction trends were to increase over tissue-on-tissue and tooth-on-tissue values, and become slightly higher yet with saline-extracted and/or "whitened" specimens. In the presence of human saliva (HSIRB# MED6000509E), composite-on-tissue CoF was reducible in the best cases to only 0.2, double that of saliva-lubricated tissue-on-tissue couples. Increased composite CoF is attributed to modifications in both composite surface chemistry and texture produced by the saline extraction and "whitening" agent exposure steps.