RESUMO
An idiopathic bone cavity (IBC) tends to rise as an abnormality in osseous growth, a degenerating tumoral process, or triggered by hemorrhagic trauma. This paper describes the interpretation of an IBC and its progression over one year. The patient's initial radiographic images showed well-defined multilocular radiolucency located at the right mandibular molar region, extending between the teeth and the mandibular basis. No clinical symptoms were present, and the course of the mandibular canal was not altered. The lesion was not initially biopsied due to the patient's dental anxiety. Over one year, the radiolucent area extended anteriorly and thinned the lingual and buccal cortices. Prior radiolucent areas changed to granular-appearing bone. The diagnosis was based on a fine-needle aspiration biopsy. The appearance of an IBC is not unique; its benign nature should be differentiated from multilocular or fibro-osseous lesions by a careful interpretation of clinical and radiological perspectives.