Carbinet

Forty bovine crowns were cut with a double-faced diamond disc, under water-cooling to obtain 40 enamel blocks (10 × 10 mm), 2 mm thick. Each block was planned with an individual abrasive silicon carbide paper (#120 grit). Next, they were individually polished with silicon carbide sandpaper (Carbinet, Buehler, Lake Bluff, IL, USA) with decreasing grain (#400, #600, #1200, and #4000) for 30 seconds in each sandpaper [13 (link), 29 (link)] to standardize the amount of enamel to be removed. Polishing was standardized using a metallic device that pressed the sample against the sandpaper.
After the end of the preparation, all samples were stored in distilled water until the beginning of the experiment.

Twenty bovine teeth were cut with a double-faced diamond disc (KG Sorensen, Barueri, SP, Brazil) under water-cooling, to obtain 40 dental blocks (5 × 5 mm, from the buccal surface of the teeth) and they were used for microhardness test. Blocks were embedded in acrylic resin (Jet-Classic, Cremer, Blumenau, SC, Brazil), leaving the buccal surface exposed. After the complete acrylic resin polymerization (approximately 1 h), the blocks were planed and polished with silicon carbide sandpaper (Carbinet, Buehler, Lake Bluff, IL, USA) with decreasing grain (#400, #600, #1200, and #4000) for 30 seconds in each sandpaper [13 (link), 29 (link)] to standardize the amount of enamel to be removed.
Finally, 1 μm grain diamond paste (Buehler, Lake Bluff, IL, USA) applied with a felt disc (Texmet 1500, Buehler, Lake Bluff, IL, USA) was used for another 30 sec.