RESUMEN
The purpose of this study was to evaluate the effect of fissurotomy on the penetration and microleakage of flowable resins for carious fissures. A total of 250 extracted premolars with early fissure caries were selected and divided into five groups according to the fissurotomy; no fissurotomy (n = 50), fissurotomy with Fissurotomy® original bur (n = 50), fissurotomy with Fissurotomy® Miro NTF bur (n = 50), fissurotomy with SF104R tapered diamond bur (n = 50), fissurotomy with 1/2 round carbide bur (n = 50). Two types of flowable resins (UniFil®Flow, Filtek®Flow) were used as sealing materials. All samples were sectioned and observed using a stereoscopic microscope after thermocycling and immersing in methylene blue solution. The adaptation of flowable resin to the fissure wall was observed using scanning electron microscopy. The penetration of flowable resin into the carious fissure was significantly increased by fissurotomy, which also decreased microleakage. Fissure preparation using different burs showed a significantly different in penetration, but did not show any difference in microleakage. Unifil®Flow showed better penetration than Filtek®Flow, but there was no significant difference in microleakage. Fissurotomy can be used to increase the penetration of flowable resin into carious fissures and decrease microleakage.