The term “occult caries” and “hidden caries” are used to describe such lesions, which are not clinically diagnosed but detected only on radiographs. A female patient aged 14 years reported for routine dental check-up. On Intraoral examination, sinus was seen in the buccal mucosa of maxillary left second premolar 25. On clinical examination the occlusal surface remained ostensibly intact; tooth was asymptomatic with no past history of pain. On radiographic examination, there was radiolucency in distobuccal aspect of 25 involving enamel, dentin and nearing pulp with presence of open apex and periapical radiolucency irt 25. With clinical and radiographic evaluation, the case was diagnosed as occult caries in relation to 25. Apexification was done with calcium hydroxide. The tooth is under observation; once radiographic barrier is formed conventional root canal treatment will be performed. Conclusion : Early diagnosis of occult lesions is the best management. As radiographs are probably the most effective method of diagnosing all occult lesions, they should be recommended at appropriate ages to aid early detection of these lesions.