[Diagnostic and surgical problems in a case of post-traumatic retention of a foreign body in the submandibular gland].

We report a particular case of a traumatically introduced foreign body in the sub-mandibular gland. A breaking object (plastic pen) penetrated, through the anterior oral floor, the submandibular gland. Such foreign bodies should be removed before suturing the wounds, as they can disturb healing and cause problems long after the accident. An adequate history, clinical and imaging studies should reveal the possibility of foreign body penetration and its localization, when it isn't previously removed. We compare the use of ultrasound detection of foreign bodies in soft tissue and conventional plain radiography, computed tomography, and magnetic resonance imaging. The usefulness of US in this kind of research does not justify TC or RM studies and allows a less invasive surgical operation.