P Farge1, L Alderete, S M M Ramos. 1. Faculté d'Odontologie, Université Lyon 1, Villeurbanne, Université de Lyon, F-69622, Lyon, France. pierre.farge@univ-lyon1.fr
Abstract
OBJECTIVES: The purpose of this study was to investigate the wetting properties of three adhesives systems on etched dentin surfaces submitted to a brief air-drying procedure, as in clinical conditions. The influence of two clinical parameters (surface temperature and surrounding hygrometry) on wetting was investigated. METHODS: Two total-etch adhesives (Excite Vivapen and Adper Scothbond 1XT) and one self-etching adhesive (GC-G Bond) were used. Superficial and deep dentin slice were obtained from six caries-free extracted third molars. Before the adhesive deposition, the dentin samples were etched with 37% phosphoric acid for different time durations. The surface topography was characterised by atomic force microscopy (AFM) observations and the wetting properties of dentin were studied by contact angle measurements. RESULTS: Unlike clinical expectations, the contact angles increased with the acid exposure time, and consequently with both surface roughness and the organic-mineral ratio of the dentin components. The wetting properties were clearly more sensitive to the surrounding relative humidity than the temperature. The contact angles values were reduced by about 50% when the relative humidity increased from 37% to 80% and by about 15% when the temperature was raised from 25 degrees C to 37 degrees C. CONCLUSION: Acid-etched dentin exposed to a brief air-drying appears as the key parameter to control the wetting properties of total-etch adhesive-dentin systems. The experimental results seem to be well described by the Cassie-Baxter approach, and suggest that dentinal tubules through an adhesive repellent contribution should account for the observed wettability decreases. Copyright 2010 Elsevier Ltd. All rights reserved.
OBJECTIVES: The purpose of this study was to investigate the wetting properties of three adhesives systems on etched dentin surfaces submitted to a brief air-drying procedure, as in clinical conditions. The influence of two clinical parameters (surface temperature and surrounding hygrometry) on wetting was investigated. METHODS: Two total-etch adhesives (Excite Vivapen and Adper Scothbond 1XT) and one self-etching adhesive (GC-G Bond) were used. Superficial and deep dentin slice were obtained from six caries-free extracted third molars. Before the adhesive deposition, the dentin samples were etched with 37% phosphoric acid for different time durations. The surface topography was characterised by atomic force microscopy (AFM) observations and the wetting properties of dentin were studied by contact angle measurements. RESULTS: Unlike clinical expectations, the contact angles increased with the acid exposure time, and consequently with both surface roughness and the organic-mineral ratio of the dentin components. The wetting properties were clearly more sensitive to the surrounding relative humidity than the temperature. The contact angles values were reduced by about 50% when the relative humidity increased from 37% to 80% and by about 15% when the temperature was raised from 25 degrees C to 37 degrees C. CONCLUSION: Acid-etched dentin exposed to a brief air-drying appears as the key parameter to control the wetting properties of total-etch adhesive-dentin systems. The experimental results seem to be well described by the Cassie-Baxter approach, and suggest that dentinal tubules through an adhesive repellent contribution should account for the observed wettability decreases. Copyright 2010 Elsevier Ltd. All rights reserved.