A Cochrane investigation found that the use of antibiotics either just before or just after surgery reduced the risk of infection, pain and dry socket after wisdom teeth are removed by oral surgeons, but that using antibiotics also causes more side effects for these patients. Twelve patients needed to receive antibiotics to prevent one infection and for every 21 people who received antibiotics, an adverse event was likely. The conclusion of the review was that antibiotics given to healthy people to prevent infections may cause more harm than benefit to both the individual patients and the population as a whole.[21]