The irrigation solutions most often used in the endodontic treatment are NaOCl 2.5% and EDTA 17%. However, these two irrigation solutions still have shortcomings. One of the natural ingredients currently being developed as an irrigation solutions alternative is Lerak fruit extract. The results showed that the Lerak fruit (Sapindusrarak DC) extract solution was antibacterial, antifungal, cleaned root canal smear layer, and more biocompatible than the NaOCl solution. F.nucleatumwas the most common bacteria found in teeth with root canal infections. This study aimed to determine the effect of Lerak fruit extract in inhibiting the Fusobacteriumnucleatum development through hydrophobicity, destructive enzyme expression, and fracture resistance. This experimental post-test only group design,

Keywords : Fracture resistance, Fusobacteriumnucleatum, Root canal, Sapindusrarak DC, Virulence.