In most cases of periapical abscess and bone resorption endodontic therapy alone is enough to return the infected teeth to a healthy state and function without surgical intervention. Biodentine a new calcium silicate based material is a material widely used in endodontic treatment because of its osteoblastic activity and biocompatibility. Biodentine was used in this case report for the conservative treatment of teeth with root resorption around the mesial root of mandibular first molar. Both the MB and ML canals were entirely filled with Biodentine to treat the root resorption process and strengthen the remaining root structure. The favorable response indicates the feasibility of using biodentine as part of orthograde endodontic treatment of teeth with resorption.