QUALITATIVE ASSESSMENT OF SURFACE CHARACTERISTICS OF FLOWABLE COMPOSITE SUBMITTED TO ACIDIC CHALLENGES.

Introduction. The aim of the present study was to evaluate, by atomic force microscopy (ATM), the surface condition and roughness parameters of low viscosity composite resins after exposure to Coca-Cola acidic drink under different immersion regimes. Materials and methods. The materials used in the present study were Filtek Ultimate Flowable Restorative(3M ESPE, St. Paul, MN, USA) and BrilliantFlow (COLTENE Whaledent, Switzerland). 20 cylindrical 5 mm in diameter and 2 mm thick samples were made from each material using plastic conformers placed on glass plates. The samples were light-cured for 40 s on both sides through the glass plates, to ensure complete polymerization of the material, then divided into two groups, as follows: Group I. Filtek Ultimate Flowable Restorative, and Group II. Brilliant Flow. Specimens from each group were then randomly divided into 5 subgroups: subgroup A, consisting of 4 control samples kept only in artificial saliva, and subsets B-E, consisting of 4 samples, one for each of the 4 immersion protocols in Coca Cola drink. The surface state of all samples was analyzed by atomic force microscopy and the roughness parameters were calculated. Results and discussion. The samples subjected to immersion in Coca-Cola were strongly corroded, compared to the control ones. The highest surface roughness value was determined for samples submerged 3 times/day in Coca Cola. Meantime, a higher Ra value was determined for the Filtek Ultimate Flowable composite than for Brilliant Flow. Conclusions. Evaluation of the surface condition of samples after immersion revealed in both materials a pattern of pitting corrosion, namely micro-holes and a preferential corrosion direction more obvious on the samples subjected to three immersions per day. [ABSTRACT FROM AUTHOR]