Wound Contamination

Many factors may contribute to the risk for surgical site infection, including the patient’s co-morbid conditions and age, quality of tissue at the surgical site, and skill of the surgeon. However, wound contamination is an extremely important factor. Surgical wounds are categorized as clean, clean-contaminated, contaminated, or dirty. Clean wounds (class I) are those that are atraumatic, without inflammation, and without a break in asepsis, and they are closed primarily. Clean wounds in head and neck surgery have a very low infection rate (<1% to 2% without perioperative antibiotics). Because of this low infection rate, routine antibiotic prophylaxis has not been recommended for clean head and neck surgeries. In clean-contaminated procedures (class II), a mucosal barrier is crossed or communication with the oral cavity occurs. Infection rates of 10% to 15% have been reported in clean-contaminated oral surgery procedures. Examples of class II operations include orthognathic surgery, placement of implants, bone grafting, and non-infected extractions. Prophylactic antibiotics may be of benefit in class II operations. Contaminated wounds (class III) include traumatic injury involving the oral mucosa and can usually be managed with only preoperative antibiotics unless other risk factors for infection are present, in which case postoperative antibiotics may also be necessary. Contaminated wounds may have an infection rate of 20% to 30% without antibiotics. Dirty wounds (class IV) are those that are actively infected or the result of trauma in which there has been a delay in treatment and there is communication with the oral cavity and the possible presence of devitalized tissue or foreign bodies. Class IV wounds may have up to a 50% rate of infection and are often managed with preoperative as well as postoperative antibiotics.

Timing of Administration and Selection of Antibiotics

Effective antibiotic prophylaxis must include proper timing of administration, as well as appropriate antibiotic selection and dose. To achieve adequate tissue concentrations, a parenteral prophylactic antibiotic should be administered 30 minutes before incision. It has been demonstrated by Burke and by Miles and colleagues that if antibiotics were not given until 4 or more hours after the injection of bacteria into a surgical site, the site became involved with the same level of inflammation or cellulitis as though no antibiotic had been administered, thus underscoring the importance of pre-procedure antibiotics.

The antibiotic selected should provide coverage against the microbes likely to be encountered in the surgical field and should cover as narrow a spectrum as possible. To cover organisms from the oral cavity, an antibiotic should be effective against streptococci, anaerobic gram-positive cocci, and anaerobic gram-negative rods. When skin structures are involved, Staphylococcus aureus and Staphylococcus epidermidis should also be covered. Additionally, involvement of sinus and nasal structures would necessitate an antibiotic effective against Haemophilus influenzae , diphtheroids, and peptostreptococci. To maintain high levels of antibiotic in tissues, the antibiotic should have a long half-life. In general, the antibiotic that best fulfills these criteria is penicillin. The decision to use antibiotics should be made with careful consideration of the patient’s overall physical condition and co-morbid diseases, complexity of the surgical procedure, and the consequences of potential infection. It must be remembered that the use of antibiotics does carry a risk for adverse reactions in up to 7% of patients receiving antibiotics. Potential adverse reactions include allergy, gastrointestinal upset, antibiotic-associated colitis, pseudomembranous colitis, and selection of resistant organisms. This chapter outlines the evidence for and against antibiotic prophylaxis to prevent surgical site infection in the most common oral surgical procedures, including orthognathic surgery, bone grafting, placement of dental implants, extraction of third molars, and management of facial trauma. It is not intended to be a systematic review or a meta-analysis, and in some cases, clear-cut recommendations are difficult to make after reviewing the literature.

Timing of Administration and Selection of Antibiotics

Effective antibiotic prophylaxis must include proper timing of administration, as well as appropriate antibiotic selection and dose. To achieve adequate tissue concentrations, a parenteral prophylactic antibiotic should be administered 30 minutes before incision. It has been demonstrated by Burke and by Miles and colleagues that if antibiotics were not given until 4 or more hours after the injection of bacteria into a surgical site, the site became involved with the same level of inflammation or cellulitis as though no antibiotic had been administered, thus underscoring the importance of pre-procedure antibiotics.

The antibiotic selected should provide coverage against the microbes likely to be encountered in the surgical field and should cover as narrow a spectrum as possible. To cover organisms from the oral cavity, an antibiotic should be effective against streptococci, anaerobic gram-positive cocci, and anaerobic gram-negative rods. When skin structures are involved, Staphylococcus aureus and Staphylococcus epidermidis should also be covered. Additionally, involvement of sinus and nasal structures would necessitate an antibiotic effective against Haemophilus influenzae , diphtheroids, and peptostreptococci. To maintain high levels of antibiotic in tissues, the antibiotic should have a long half-life. In general, the antibiotic that best fulfills these criteria is penicillin. The decision to use antibiotics should be made with careful consideration of the patient’s overall physical condition and co-morbid diseases, complexity of the surgical procedure, and the consequences of potential infection. It must be remembered that the use of antibiotics does carry a risk for adverse reactions in up to 7% of patients receiving antibiotics. Potential adverse reactions include allergy, gastrointestinal upset, antibiotic-associated colitis, pseudomembranous colitis, and selection of resistant organisms. This chapter outlines the evidence for and against antibiotic prophylaxis to prevent surgical site infection in the most common oral surgical procedures, including orthognathic surgery, bone grafting, placement of dental implants, extraction of third molars, and management of facial trauma. It is not intended to be a systematic review or a meta-analysis, and in some cases, clear-cut recommendations are difficult to make after reviewing the literature.

Orthognathic Surgery

The use of antibiotic prophylaxis in patients undergoing orthognathic surgery has been a point of controversy for many years ( Table 8-1 ). The overall complication rate associated with orthognathic surgery is low. The reported range of infectious complications has been broad—Alpha and colleagues found a 3.4% to 33.3% infection rate reported in the literature for mandibular osteotomies. Most studies, however, have reported lower infection rates. Alpha and colleagues performed a retrospective evaluation of 1066 mandibular sagittal osteotomies and found a 6.5% incidence of infection requiring plate removal. Similarly, Kim and Park found an infection rate of 1% in their retrospective review of 301 patients who underwent orthognathic surgery. Chow and co-workers found a 9.7% complication rate in a retrospective review of 2910 orthognathic procedures. Of these complications, 7.4% were related to infection. Before their review there was no clear consensus on the necessity for prophylactic antibiotics in orthognathic surgery. In Chow and co-workers’ study it was found that patients undergoing surgery on both jaws had a significantly higher risk for infection, with 92.7% of infected patients having surgery on both jaws. However, the duration of the surgery did not correlate with infective risk. In this study 21.6% of infections occurred within the first postoperative week; 51% involved the maxilla (all of which were segmentalized Le Fort I osteotomies) and 49% involved the mandible. It was found that patients who received only one preoperative antibiotic dose had a significantly higher rate of infection than did those who received preoperative and postoperative antibiotics. The duration of postoperative antibiotics ranged from 2 to 14 days and did not significantly affect the infection rate. Furthermore, there was no significant difference between penicillin and non-penicillin antibiotics in preventing postoperative infection. The conclusion of this study was that administration of only a single preoperative dose of antibiotics was not recommended for prophylaxis. In this study patients who had received postoperative antibiotics in addition to a preoperative dose had a lower infection rate than did those who had received only a preoperative dose, although the optimal duration of postoperative antibiotic administration was not as clear, but it was thought that at least 2 postoperative days of antibiotics was useful.

Zijderveld and associates found that a single preoperative dose of antibiotics resulted in a significantly lower risk for infection than in cases in which no antibiotics were given at all. This randomized, double-blind, placebo-controlled study compared single preoperative doses of amoxicillin-clavulanate with cefuroxime and demonstrated an 11.1% infection rate in the amoxicillin-clavulanate group, a 17.6% infection rate in the cefuroxime group, and a 52.6% infection rate in the placebo group. Their conclusion was that antibiotic prophylaxis consisting of a single preoperative dose resulted in a reduced risk for complications and that there was no significant difference between the two antibiotics evaluated, although the power of the study may have been too low to demonstrate a difference between the two antibiotics.

The duration of postoperative prophylactic antibiotics in patients undergoing orthognathic surgery has been examined on numerous occasions. Ruggles and Hann performed a prospective, randomized, double-blind study comparing the use of only peri-operative intravenous antibiotics versus peri-operative plus 2-day postoperative intravenous antibiotics in 40 patients undergoing orthognathic surgery. The study population included 53 osteotomies, with seven patients undergoing simultaneous bone grafting and four patients undergoing simultaneous allograft augmentation. All patients received one preoperative intramuscular dose of penicillin, as well as intravenous penicillin every 3 hours intraoperatively and one dose 3 hours postoperatively. In addition, the study group received 2 additional days of intravenous penicillin every 4 hours, whereas the placebo group received intravenous placebo for 2 days. Patients were monitored for infection, which was defined as meeting any three of the following defined criteria: elevation of body temperature longer than 72 hours or a sudden rise in body temperature postoperatively with return to normal; increasing edema, induration, and erythema of the wound margin and surrounding tissue; unusual surgical site pain; elevated white blood cell count with a leftward shift; or suppurative drainage from surgical site. In three patients, all of whom were in the group receiving only peri-operative antibiotics, an infection with purulent drainage developed 1 to 2 weeks postoperatively. This observed increased number of infections in the group receiving only peri-operative antibiotics versus postoperative antibiotics was not statistically significant. This study was published in 1984, and a limitation of the study may be the fact that intravenous antibiotics were used postoperatively for 2 days. Today, it is unlikely that all orthognathic patients would be hospitalized for 2 days postoperatively to receive intravenous antibiotics.

Fridrich and colleagues performed a prospective study comparing the use of peri-operative antibiotics and postoperative antibiotics for 1 week in 30 orthognathic surgery patients. There was no significant difference in infection rates between the two groups, again indicating that prolonged periods of postoperative antibiotics do not offer an advantage over peri-operative dosing.

The dosing protocol was also examined by Lindeboom and co-workers in a prospective randomized study of prophylactic antibiotic use in patients undergoing bilateral sagittal split osteotomies. Seventy patients undergoing a total of 140 mandibular osteotomies were assigned to either single preoperative dosing or 24-hour dosing with clindamycin. The preoperative dose was administered intravenously 15 minutes before the incision. Postoperatively, patients received either intravenous clindamycin every 6 hours for four doses or intravenous placebo every 6 hours for four doses. Surgical wounds were examined for pain, swelling, erythema, inflammation, or purulence postoperatively. There was a 5.6% infection rate in patients receiving only preoperative antibiotics and a 2.8% infection rate in those receiving antibiotics preoperatively and for 24 hours postoperatively. There was no statistically significant difference in infection rate between these two dosing schedules, and the authors thought that long-term antibiotic prophylaxis was not advantageous in orthognathic surgery.

Bentley and associates performed a prospective, randomized, double-blind trial examining 1-day versus 5-day antibiotic prophylaxis for orthognathic surgery in 30 patients. This study revealed a 60% infection rate in patients receiving antibiotics for 1 day postoperatively versus a 6.7% infection rate in patients receiving 5 days of postoperative antibiotics, which was a significant difference. Of note, however, wire osteosynthesis and maxillo-mandibular fixation (MMF) were used instead of plates and screws, so translation of these results to cases in which plates and screws and no MMF are used is questionable. Additionally, 90% of the infections were found in the mandibular incision, and it was postulated by the authors that perhaps the wound breakdown in these incisions was due to the use of feeding catheters by the patients. Furthermore, as was pointed out in the discussion of this particular article by Abubaker, the definition of infection was rather broad and included purulent drainage, serosanguineous drainage with a positive culture (could be contaminated), spontaneous wound dehiscence, and the surgeon’s diagnosis of infection. Although these results seem to be in opposition to those of other studies in which it was suggested that prolonged postoperative antibiotics are not necessary, when taken in consideration with the potential limitations of this study, it does not entirely refute these other studies.

Overall, the evidence is not clear-cut but does seem to support the use of at least peri-operative prophylactic antibiotics to prevent infection in orthognathic surgery. Although the ideal duration of postoperative antibiotics is not definitively known, there is no evidence to support a prolonged duration of postoperative antibiotics.

Bone Grafting

Antibiotic prophylaxis of intraoral onlay bone grafting in preparation for dental implant placement has not been studied extensively ( Table 8-2 ). Lindeboom and van den Akker performed a prospective, placebo-controlled, double-blind trial examining antibiotic prophylaxis for onlay bone grafting using a ramal donor site. In their study, 20 patients were randomized to receive either placebo or a single preoperative dose of oral phenethicillin. Patients were observed for 30 days for evidence of infection as demonstrated by either purulence, serosanguineous drainage with a positive culture, spontaneous dehiscence, or pain necessitating wound exploration with a resultant positive wound culture. The trial was ended early when the infection rate was determined to be high and it was found that two patients had recipient site infections, one had a donor site infection, and two had both sites infected. All these patients had been in the placebo group. This study had low power, but the authors concluded that a single preoperative dose of oral antibiotics was efficacious in decreasing the risk for infection in onlay bone grafting. However, the statistical analysis used to evaluate the data from this study was inappropriate, as pointed out in a subsequent letter to the editor written by Brennan and co-authors. The authors of the letter to the editor thought that the results of the study were not statistically significant once the proper statistical analysis was used. In response, Lindeboom and colleagues agreed that their statistical analysis was incorrect, but they thought that at the very least their results were clinically significant.

In a follow-up study, Lindeboom and co-workers performed a randomized prospective, controlled, double-blind trial comparing a single preoperative dose of phenethicillin and a single preoperative dose of clindamycin for prophylaxis of ramal onlay bone grafts involving the maxilla. Antibiotics were administered orally 1 hour before the procedure and the patients were observed for 8 weeks for the development of signs of infection at the recipient site, as defined in the previously mentioned study. This follow-up study did not have a placebo arm, enrolled 150 patients, and had adequate power (80%). The recipient site infection rate in the phenethicillin group was 5.3%, and in the clindamycin group it was 2.7%. This study did not demonstrate a significant difference between the two antibiotics in efficacy in preventing infection in onlay bone grafting.

In light of the limited number of studies of antibiotic prophylaxis in patients undergoing onlay bone grafting, it is difficult to ascertain a conclusion. It seems that based on the findings of Lindeboom and van den Akker, at least a preoperative dose of antibiotics should be considered. Ideally, a prospective, randomized, controlled, double-blind trial with adequate power should be completed to address this question.

Sinus lifting presents another interesting scenario in which systemic antibiotic prophylaxis has not been closely evaluated. It is estimated that infectious complications in sinus lifting could range in frequency from 2% to 7%. Several studies involving local (topical—mostly tetracycline) antibiotic use in bone grafting for oral surgical and periodontal procedures have been performed, but few studies have examined systemic antibiotics in this context. Furthermore, the antibiotics that have been examined are typically those with a broad spectrum of activity rather than antibiotics that target anaerobic bacteria (such as metronidazole), which might be expected to play a role in infection of sinus lift bone grafting. Choukroun and associates performed an interesting study of antibiotic use in sinus lifts. They studied 94 sinus lifts performed with freeze-dried bone graft in 72 patients. Eighty-two sinus lifts were performed with a 0.5% metronidazole solution mixed into the graft material and 12 sinus lifts were performed without metronidazole. All patients received amoxicillin for 6 days postoperatively. The patients were monitored with computed tomography to assess homogeneity of the grafts. Sinus lifts performed with metronidazole were found to be more significantly homogeneous than were those performed without metronidazole. The non-homogeneity within the bone grafts performed without metronidazole was theorized to be potentially associated with bacterial contamination of the graft. Although this study is interesting, more research should be done to examine the use of antibiotic prophylaxis in sinus lift procedures before definitive recommendations on antibiotic prophylaxis can be made.

Implants

Placement of dental implants poses an interesting scenario because one must consider that bacterial contamination at the time of implant insertion can result in subsequent non-integration and ultimately implant loss. Once a biomaterial, such as titanium, is infected, such infected surfaces are resistant to eradication with antibiotics and are difficult to treat, with removal of the implant often being required. The development of an infection around an implant is potentially influenced by the skill of the surgeon, as well as maintenance of asepsis during the surgery. The most likely bacteria to cause implant infection include streptococci, anaerobic gram-negative rods, anaerobic gram-positive cocci, and anaerobic gram-negative cocci. The ideal antibiotic should be bactericidal against the flora expected. Placement of dental implants is considered a class II, or clean-contaminated, surgical procedure. The value of prophylactic antibiotics in implant surgery has been examined in various trials throughout the years ( Table 8-3 ).

Dent and colleagues performed one of the earliest studies examining the use of prophylactic antibiotics in implant surgery as part of the comprehensive Dental Implant Clinical Research Group (DICRG). A total of 2641 implants were studied in this randomized prospective trial. Investigators were permitted to determine whether to provide antibiotics, what type of antibiotic was to be used, and how the antibiotic was to be administered. Preoperative antibiotics were administered to 54.8% of the patients and postoperative antibiotics to 96%. Failure of the implant was recorded either during the healing phase or at phase II surgery. Patients who did not receive preoperative antibiotics exhibited a higher failure rate both during healing and at stage II. Patients who did receive preoperative antibiotics had a 1.4% failure rate as compared with a 4% failure rate observed in patients who did not receive preoperative antibiotics. The risk for failure was two to three times higher if preoperative antibiotics were not used. Although this study supports the use of preoperative antibiotics, it should be noted that it was not a controlled, blinded trial with well-defined parameters.