Tuberculous infection of the oral tissues is a rare finding. An interesting case of primary tuberculosis of mouth is described, presenting as persistent discharge of pus from the lower wisdom tooth region. Incisional biopsy revealed features of an infected dentigerous cyst while histopathological examination of the excised lesion showed keratinizing cyst with secondary infection. Non-healing of the bony defect prompted curettage of the area and the submitted sample microscopically showed granuloma with characteristic Langhans' giant cells, raising the suspicion of underlying systemic tuberculosis. The importance to the dental surgeon in the recognition, especially by use of pathological examination, is emphasized and also the value of diagnosis for the patients and the community.