Root resorption, usually found through radiographic examinations is an internal or external injury. Since root resorption is a multidisciplinary problem, it requires a variety of knowledge for understanding the etiology and pathogenesis of the disease. Objective: This study aimed to demonstrate the importance of how a correct and early diagnosis facilitates the evaluation of the best treatment for each case, assuring a favorable prognosis. Case report: A radiographic finding in a 25-year-old young male showed the presence of an internal root resorption and apical periodontitis in tooth #22. After endodontic therapy and monthly calcium hydroxide dressing changes, the root canal filling was conducted and the case was radiographically followed-up. Conclusion: An accurate initial examination, with a carefully detailed anamnesis and periapical radiographs are vital points for a correct diagnosis, treatment and,