Investigation of the Electric Handpiece-related Pneumomediastinum and Cervicofacial Subcutaneous Emphysema in Third Molar Surgery

Pneumomediastinum and/or cervicofacial subcutaneous emphysema are extremely rare but severe complications in third molar surgery. The most common cause is compressed air exhaust from an air-driven high-speed handpiece. To prevent these complications, treatment with an electric handpiece that does not use the drive air is generally recommended; however, its safety has not been fully verified. In this study, we investigated electric handpiece-related emphysema during third molar surgery. We evaluated patients who visited our hospital in relation to third molar surgery between January 2008 and December 2017. Of the 2938 patients examined, 2 patients were complicated with electric handpiece-related pneumomediastinum and cervicofacial subcutaneous emphysema during sectioning the mandibular third molar. In these cases, a straight motor handpiece and a 1:5 speed increasing contra-angle motor handpiece were used, respectively. Both patients received antibiotics and follow-up examination under hospitalization. Although the air flow and pressure of an electric handpiece are lower than those for air-driven high-speed handpieces, the air expelled from electric handpieces could cause cervicofacial emphysema and/or pneumomediastinum. It should be noted that electric handpieces do not use the drive air, however, most of these handpieces have air/water nozzles and use tip air. Before treatment, an informed consent to patients about the risk of emphysema is mandatory. With regard to the surgical technique, elevation of the mucoperiosteal flap should be minimal. Attention should be also paid to the possibility that the air inflow route is made through removal or perforation of the cortical bone. To prevent emphysema, an electric surgical handpiece with an external water spray may be preferable for removing the bone and cutting the tooth, because this type of surgical handpiece has a separate water drip for cooling instead of combined water and air spray, and it does not use the flux of air.