Subcutaneous emphysema is a relatively rare complication in dental treatment. This paper reports a case of subcutaneous emphysema that arose after CO2 laser irradiation. A nine-year-old girl underwent irradiation with CO2 laser to resect the upper labial frenum at a dental clinic. On the same day, the patient was referred to our hospital with facial swelling. CT examination revealed subcutaneous emphysema. The patient was hospitalized and received anti-inflammatory treatment. She was discharged after three days, and the swelling subsided within seven days. Efforts should be made to master the proper technique for using CO2 laser and to recognize the possibility of complication when conducting CO2 laser irradiation.
