Laird Harrison

June 29, 2012

June 29, 2012 — Antibiotics may not prevent infection with implants and third-molar surgery, according to researchers presenting 2 studies at the International Association of Dental Research (IADR) 90th General Session and Exhibition, held in Iguacu Falls, Brazil.

In a study on implant placement, researchers found no difference in adverse events whether patients took a placebo or amoxicillin or whether they took the amoxicillin before or after the surgery.

In a separate study on third-molar surgery, in which all patients received amoxicillin before surgery, there was no difference between those who also received amoxicillin afterward and those who did not.

"Therefore, preoperative amoxicillin in a single dose and postoperative [amoxicillin] in multiple doses was not more effective than a single preoperative dose for the evaluated parameters," investigator Waldyr A. Jorge, DDS, PhD, professor of dentistry at the University of São Paulo, Brazil, told Medscape Medical News in an email.

The question of when to use antibiotics in implant and third-molar surgery has been controversial, with the fear of infection balanced against concerns about antibiotic resistance, allergies, and other adverse reactions, he noted.

Standard recommendations "are still missing about antibiotics in implant surgery among professional and government organizations," Tan Wah Ching, MDS, professor of restorative dentistry at the National Dental Centre of Singapore and first author of the study on antibiotics with implant surgery, told Medscape Medical News in an email.

Dr. Jorge and colleagues extracted both third molars from 29 patients (position IIB in the Pell-Gregory classification). The researchers performed the 2 extractions 28 days apart.

All patients took 1 g amoxicillin before the surgery.

The patients acted as their own controls, with patients randomly assigned to receive 500 mg amoxicillin every 8 hours for 7 days after the surgery with 1 extraction and a postoperative placebo with the other extraction.

The researchers measured pain, wound infection, trismus, temperature, swelling, dysphagia, adverse effects, and lymphadenopathy at baseline and 4 and 7 days after surgery.

They found no significant difference (P > .05) between treatment or no treatment for any of these parameters.

Still, American Association of Maxillofacial Surgery spokesman Thomas B. Dodson, DMD, MPH, associate professor of oral and maxillofacial surgery at Harvard University in Cambridge, Massachusetts, told Medscape Medical News that he recommends giving antibiotics with mandibular third-molar surgery.

"If one looks at the weight of all the studies together, it looks like there is some benefit in decreasing the risk of surgery site infection," said Dr. Dodson, who was not associated with either study.

The risk for complications with mandibular third-molar extractions is about 5%, he said.

In his own research, Dr. Dodson used intravenous antibiotics and found a slight benefit. Intravenous antibiotics are practical because from 60% to 80% of patients undergoing third-molar surgery in the United States receive intravenous sedation, so antibiotics can easily be added in the same line as the sedative, he said.

In addition, intravenous administration is easier to control and the antibiotics get into the blood more quickly than with oral administration, he noted.

He added that Dr. Jorge's study did not show whether antibiotics were effective in third-molar surgery. "What they showed was that their method didn't work," he said. "But that doesn't mean antibiotics don't work."

He had a similar reaction to the implant study.

In that study, Dr. Tan and colleagues randomly assigned 282 healthy adults to 1 of 4 groups:

  • group 1, with 71 patients, received 2 g oral amoxicillin 1 hour before surgery;

  • group 2, with 69 patients, received 2 g oral amoxicillin immediately after surgery;

  • group 3, with 71 patients, received 2 g oral amoxicillin 1 hour before surgery and 500 mg 3 times a day on days 2 and 3 after surgery; and

  • group 4, with 71 patients, received 2 g placebo 1 hour before surgery.

Examiners who did not know who was in which group examined the patients at weeks 1, 2, 4, and 8 for complications.

The patients used visual analogue scales to indicate their pain, swelling, bruising, and bleeding for days 1 through 7 and day 14.

At week 1, 97.18% of group 1, 95.59% of group 2, 97.14% of group 3, and 94.37% of group 4 had closed flaps.

In group 3, 20% of the patients had pain and 26% had swelling.

All flaps were closed and none of the patients reported pain at week 8.

One patient in group 3 had suppuration.

At week 8, all implants were stable at except 1 each from group 1 and group 3.

The patients in all the groups had very little bleeding, swelling, pain, or bruising, and reported less and less of these adverse effects from day 1 to day 14.

Overall, the researchers found no statistically significant differences between any of the groups at the various times (P < .0001).

They concluded that prophylactic systemic antibiotics were "redundant," whether before, after, or both before and after surgery, in routine single implant placement.

Dr. Dodson disagreed. "On average, there is probably a benefit to the use of antibiotics," he said.

Because infections in implants are rare, a much larger study, one with thousands of patients, might be required to detect differences among patients who got antibiotics and those who did not, he said.

In his own practice, he gives prophylactic antibiotics because sometimes after beginning the procedure he realizes he needs to graft the implant site.

"If I knew before I started the operation that the only thing I was going to do was give an implant, I wouldn't use antibiotics," he said. "But about half the time I put the implant in I have to do some grafting. Graft material can get contaminated with bacteria."

Dr. Tan, Dr. Jorge, and Dr. Dodson have disclosed no relevant financial interests.

International Association of Dental Research (IADR) 90th General Session and Exhibition: Abstract 161350, presented June 23, 2012; abstract 2518, presented June 22, 2012.