Within five days of having wisdom teeth removed, most patients experience relatively little pain, but most still have well over half of their opioid painkiller prescription left, a new study finds.

“When translated to the broad U.S. population, our findings suggest that more than 100 million opioid pills prescribed to patients following surgical removal of impacted wisdom teeth are not used, leaving the door open for possible abuse or misuse by patients, or their friends or family,” said study author Dr. Brandon Maughan of the University of Pennsylvania.

The study included 79 patients who had their wisdom teeth removed, according to HealthDay. Three weeks after their surgery, only five had finished their prescribed opioid painkillers. The findings appear in the journal Drug and Alcohol Dependence.