Purpose: To evaluate the durability of a resin coating system after toothbrushing abrasion resistance and surface hardness of the coating resin. Methods: Rectangular blocks of Top Coat (TC) or the bonding resin of the two-step self-etching adhesive Clearfil SE Bond (SEB) were prepared by irradiation with halogen light units. After immersion in distilled water at 37 degrees C until stabilized water absorption, the specimens were subjected to toothbrushing abrasion tests in which a toothbrush was moved on the specimen at 60 strokes/minute with a 400 gf vertical load with toothpaste slurry. The specimens were weighed after every 10,000 strokes until 200,000 strokes. Hardness of the specimen was measured with a Knoop hardness tester, and the degree of cure was determined using ATR-FTIR spectroscopy. Statistical differences between materials were analyzed using a Student's t-test. Results: TC demonstrated significantly less weight loss than SEB after 40,000 strokes (P<0.05), showing 0.87 +/- 0.64 mg loss after 200,000 strokes. The Knoop hardness number of TC was significantly greater than that of SEB (P<0.05), and TC presented a greater degree of cure. (Am J Dent 2010;23:70-74).