Careful examination of the oral cavity in respiratory medicine is often neglected, although it represents sometimes a clue for clinical diagnosis and it is important in completely addressing the patient. On the other hand, the dental practitioner who treats a patient with unusual oral lesions should observe correct guidance and medical advice. Oral manifestations are of polymorphic nature, being associated with a variety of pulmonary diseases and specific therapies. Respiratory obstructive diseases, systemic diseases with pulmonary involvement, lung cancer, cystic fibrosis or tuberculosis all have clinical and/or therapeutic involvement of the oral cavity, which underlines the necessity of regular dental services and careful oral cavity exam, as well as an active collaboration between dental practitioners and pulmonologists or somnologists, for patient’s ultimate benefit