We present the case of a 32-year-old male patient complaining of recurrent mandibular pain for 3.5 years. Panoramic radiography indicated increased cortical density of the mandibular lower border. Scintigraphy and single-photon emission computed tomography revealed metabolic hyperactivity in that region without pathologic lymph nodes. A bone biopsy specimen of the mandibular lower border did not have inflammation or cytologic atypia. Endocrinologic investigation confirmed secondary hyperparathyroidism as a result of hypovitaminosis D. Several weeks after starting therapy with oral vitamin D supplements, the symptoms completely disappeared. Increased cortical density is a rare manifestation of secondary hyperparathyroidism, which normally causes the lamina dura to vanish and produces a ground-glass appearance as a result of blurring of the trabecular bone pattern. Because focal hyperostosis can have multiple benign or malignant causes, radiologic examination of the jaw bones is indispensable for evaluating orofacial pain. Increased cortical density may be caused by metabolic diseases, requiring further investigations, including biopsy and blood analysis.