Introduction: Internal resorption, which starts in the pulpal cavity, either in the pulpal chamber or in the root canal, is a very uncommon resorption of dentine that continues to destroy the surrounding dental hard tissues. Other aetiological reasons have been proposed; however trauma or persistent pulpal inflammation are likely to be the initial events in internal root resorption. Treatment for minor internal resorption lesions has a favorable prognosis. However, the prognosis is poor and tooth extraction must be considered if the tooth structure has been significantly compromised and perforation has occurred. Case Report: A 36-year-old male patient came to the department with a chief complaint of dull pain in lower right back tooth region in the last one month.The clinical examination showed distal caries in tooth no 45. Caries was also present in tooth no 46. Conclusion: Internal resorption is an uncommon condition with most of cases being idiopathic. The detection of internal resorption can be done in routine radiographs, while others require advanced diagnostic techniques like dental CT scans for its diagnosis.