Officials at the Vastmanland Central Hospital in Vasteras said the drill became loose and fell into the mouth of a 60-year-old woman, who was undergoing dental implant surgery last September, The Local.se reported Friday.
"She tried to spit it out, and was made to cough, but she'd already swallowed," said Per Weitz, the hospital's medical chief.
Weitz said an X-ray revealed the drill was lodged in the woman's right lung and a bronchoscopy was performed to remove the object.
"A pinky-sized tube was sent into her lung with a small camera and pliers to grab hold of the drill," Weitz said.
Doctors said the woman made a full recovery about a month after the incident.
The incident was reported to the National Board of Health and Welfare and Weitz said new precautions are being adopted to prevent further occurrences.