Sir, we would like to bring to the attention of the reader two unusual cases which we have recently seen.

Both patients were referred to us following routine scaling of lower teeth using an ultrasonic scaler and high volume suction, in dental practices. Both described similar accounts of a sudden pain in the floor of the mouth followed by the sensation that tissue was sucked into the aspirator tip for a number of seconds. Immediate swelling of the floor of the mouth and neck was experienced by both of these patients. Treatment was ceased immediately and the patients were referred on an urgent basis. Crepitus, as the characteristic finding of subcutaneous air, was evident in the anterior triangles of the patients' necks bilaterally. Further examination showed that two small puncture wounds were noted in the floor of the mouth of each patient. These patients were fortunate not to require any surgical airway intervention but were treated with prophylactic antibiotics and admitted to hospital for a period of observation. The surgical emphysema resolved spontaneously over some days.

We hypothesise that the puncture wounds made inadvertently by the ultrasonic scaling tip acted as a flap-type valve. Air was drawn into the floor of the mouth when tissue was sucked in to the aspirator tip with subsequent spread of air into the neck along normal anatomical tissue planes.

Surgical emphysema can be a complication of a number of dental and maxillofacial procedures. The exhaust of an air rotor drill can sometimes inject a small volume of air into submucosal or subcutaneous tissues. Defects of the anterior wall of the maxillary sinus can predispose to surgical emphysema if patients blow their nose against resistance. This increases the intra-antral pressure and air can escape into the soft tissues. These include patients who have recently had maxillary osteotomies, patients with zygomatic fractures, and also individuals who have oro-antral fistulae closed surgically.

We feel that practitioners should be aware of this unusual complication that can arise during a routine and very commonly performed procedure.

1. Blackburn