the oral cavity harbors a large number of organisms , which can delay normal wound healing or cause infection in a surgical region . indeed , surgical site infection and aspiration pneumonia are common complications following oral surgery 


 , with the former as an important cause of prolonged hospitalization and reduced patient quality of life . in head and neck cancer patients , the rate of surgical site infection ranges from 10% to 45% , with previous chemotherapy , performance of a tracheotomy , free flap reconstruction , blood loss volume , and hypoalbuminemia noted as risk factors 






 . these findings suggest that severely invasive surgery ( i.e. , reconstructive surgery , flap surgery ) and host nutritional status are predictive risk factors for head and neck cancer patients . in addition , a recent study showed that preoperative oral health care can reduce the risk of surgical site infection , indicating its importance to reduce postoperative complications 
 . however , few studies have been performed to determine predictive risk factors related to postoperative complications in patients who undergo oral surgery , except for oral cancer cases . in the present study , we focused on patients who underwent mildly to moderately invasive oral surgery in order to clarify significant risk factors related to postoperative complications in the oral cavity . this study reviewed the records of 324 patients ( 171 males , 153 females ; with a mean age of 41.0 years , ranging from 5 to 84 years ) who underwent surgical treatment in the operating room under general anesthesia or intravenous sedation at the department of oral and maxillofacial reconstructive surgery , hiroshima university hospital , from 2012 and 2014 . subjects included in this study were those who underwent an operation for impacted tooth extraction , cyst excision , fixation of mandibular and maxillary fractures , jaw deformity ( osteotomy ) , resection of a benign tumor , sinus lifting , bone grafting , removal of a sialolith , and others . oral cancer patients who underwent primary resection , neck dissection , and reconstructive surgical procedures were excluded from the analysis . table 1summary of surgical procedures performed in the present casessurgical procedurespatients ( % ) impacted tooth extraction107 ( 33.0%)excision of jaw bone cyst / radicular cyst94 ( 29.0%)fixation of mandibular / maxillary fracture41 ( 12.7%)resection of benign tumor34 ( 10.5%)jaw bone osteotomy for jaw deformity27 ( 8.3%)sinus lifting9 ( 2.8%)removal of sialolith5 ( 1.5%)bone graft5 ( 1.5%)frenuloplasty1 ( 0.31%)excision of sublingual gland and mucocele1 ( 0.31% ) 
  clinical data obtained included patient age , sex , medical history , blood loss volume , and operation duration . as for the antibiotic drugs given , cephem antibiotics ( e.g. , cefdinir , cefmetazole , cefaclor , cefditoren pivoxil , flomoxef ) and penicillin antibiotics ( ampicillin ) were administered in all cases for 3 - 7 days after the operation . we also investigated the occurrence of complications such as anastomotic leak and surgical site infection within 14 days after surgery . surgical site infection was determined according to the method of jonson , et al . fisher s exact test and a multivariate logistic regression model were used for statistical analysis , with p values less than 0.05 regarded to be statistically significant . in addition , a mann - whitney u test was utilized for nonparametric statistical analysis of serum albumin level , blood loss volume , and duration time . we investigated the relationship between clinical factors and postoperative complications ( e.g. , surgical site infection , anastomotic leak ) . of which four showed surgical site infection and 32 an anastomotic leak without a distinct infection sign . then , we analyzed the correlation between postoperative complications and clinical factors including gender , age , diabetes , respiratory disorder , cardiovascular disease , preoperative serum albumin level , surgical procedure , blood loss volume , and operation time ( fisher s exact test ) ( table 2 ) . as for antibiotic drugs , there were no apparent effects of a specific antibiotic on postoperative complications ( data not shown ) . on the other hand , the percentage of complications was increased in diabetic ( 33.3% ) as compared to non - diabetic ( 10.3% ) patients ( table 2 ) , and also increased in patients with low level of serum albumin ( 29.2% ) as compared to those with a high level ( 9.7% ) ( table 2 ) . in univariate analysis , we found a significant relationship between postoperative complications and diabetes ( p=0.033 ) , preoperative serum albumin level ( p=0.009 ) , and operation duration ( p=0.0093 ) ( table 2 ) . next , those three variables were evaluated using a multiple logistic regression model . as shown in table 3 , preoperative serum albumin level ( < 4.0 g / dl ) and operation time ( 120 minutes ) were found to be independent risk factors affecting postoperative complications ( odds ratio 3.82 , p=0.0074 ; odds ratio 2.83 , p=0.0086 , respectively ) . table 2correlation between clinical characters and postoperative complications  postoperative complications  clinical characteristics(-)(+)p valuegender  male ( 171)150 ( 87.7%)21(12.3%)0.60female ( 153)138 ( 90.2%)15 ( 9.8% )  age in years  < 60 ( 253)226 ( 89.3%)27 ( 10.7%)0.6760 ( 71)62 ( 87.3%)9 ( 12.7% )  diabetes  ( - ) ( 312)280 ( 89.7%)32 ( 10.3%)0.033*(+ ) ( 12)8 ( 66.7%)4 ( 33.3% )  cardiovascular disease  ( - ) ( 287)255 ( 88.9%)32 ( 11.1%)1.0(+ ) ( 37)33 ( 89.2%)4 ( 10.8% )  respiratory disease  ( - ) ( 315)280 ( 88.9%)35 ( 11.1%)1.0(+ ) ( 9)8 ( 88.9%)1 ( 11.1% )  preoperative serum albumin  < 4.0 g / dl ( 24)17 ( 70.8%)7 ( 29.2%)0.0099**4.0 g / dl ( 300)271 ( 90.3%)29 ( 9.7% )  surgical procedure  impacted tooth extraction ( 107)97 ( 90.7%)10 ( 9.3%)0.27excision of jaw bone cyst ( 94)87 ( 92.6%)7 ( 7.4% )  fixation of fractures ( 41)34 ( 82.9%)7 ( 17.1% )  resection of benign tumor ( 34)30 ( 88.2%)4 ( 11.8% )  jaw bone osteotomy ( 27)24 ( 88.9%)3 ( 11.1% )  sinus lifting ( 9)6 ( 66.7%)3 ( 33.3% )  removal of sialolith ( 5)4 ( 80.0%)1 ( 20.0% )  bone graft ( 5)4 ( 80.0%)1 ( 20.0% )  frenuloplasty ( 1)1 ( 100.0%)0 ( 0.0% )  excision of sublingual gland ( 1)1 ( 100.0%)0 ( 0.0% )  blood loss  < 300 ml ( 307)274 ( 91.3%)33 ( 10.7%)0.42300 ml ( 17)14 ( 82.4%)3 ( 17.6% )  operation time  < 120 min ( 269)245 ( 91.1%)24 ( 8.9%)0.0093**120 min ( 55)43 ( 78.2%)12 ( 21.8% )  fisher s exact test was used for statistical analysis . statistical significances of p<0.05 and p<0.01 were indicated by * and * * respectively 
  fisher s exact test was used for statistical analysis . statistical significances of p<0.05 and p<0.01 were indicated by * and * * respectively 
 table 3multivariate logistic regression analysis of predictive factors for postoperative complicationsvariablesodds ratio95% confidence intervalp valuestep 1  diabetes ( + ) 3.720.97 - 14.30.056preoperative serum albumin ( < 4.0 g / dl)3.351.22 - 9.20.019operation time ( 120 min)2.891.31 - 6.350.0084step 2  preoperative serum albumin ( < 4.0 g / dl)3.821.43 - 10.20.0074**operation time ( 120 min)2.831.30 - 6.170.0086**a multivariate logistic regression model was used for statistical analysis . statistical significances of p<0.05 and p<0.01 were indicated by * and * * respectively 
  a multivariate logistic regression model was used for statistical analysis . statistical significances of p<0.05 and p<0.01 were indicated by * and * * respectively among the continuous variables , preoperative serum albumin , blood loss volume , and operation duration were examined using a mann - whitney u test for nonparametric statistical analysis . preoperative serum albumin level was significantly lower in patients who developed a surgical site infection or anastomotic leak ( p=0.025 ) . in addition , blood loss volume ( p=0.014 ) and operation duration ( p=0.0065 ) were significantly increased in patients with postoperative complications . these results suggest that low serum albumin , increased blood loss volume , and prolonged operation time are importantly associated with postoperative complications following oral surgery ( table 4 ) . table 4correlation between postoperative complications and serum albumin level , blood loss , or operation time  postoperative complications  variables(-)(+)p valuepreoperative serum albumin ( g / dl)4.530.394.330.480.025*blood loss ( ml)65.6142.5104.0168.50.014*operation time ( min)84.571.0108.475.20.0065**mann - whitney u test was utilized for nonparametric statistical analysis of serum albumin level , blood loss volume , and duration time . statistical significances of p<0.05 and p<0.01 were indicated by * and * * respectively 
  mann - whitney u test was utilized for nonparametric statistical analysis of serum albumin level , blood loss volume , and duration time . postoperative complications often result in prolonged hospital stay and reduced quality of life in affected patients . therefore , it is important to identify risk factors associated with postoperative complications and eliminate them as much as possible . in this study , we examined some clinical factors to determine their relationship with postoperative complications such as surgical site infection and anastomotic leak . of 36 cases with complications , four had an apparent infection in the surgical region , whereas most ( n=32 ) had an anastomotic leak . in our patients , the administration of antibiotic prophylaxis may have reduced the opportunity for infection , resulting in the relatively small number of surgical site infection cases in the present cohort . albumin level , in particular , is thought to be a reliable marker of nutritional status in patients following surgery 
 , with a decreased level associated with rheumatoid disease , indicating it as a promising marker of inflammatory disease 
 . thus , that level is also considered to be a significant and useful factor to assess malnutrition and inflammation in patients . in addition , serum albumin is thought to be a predictive nutritional parameter for patients with head and neck cancer 
 . in a previous study , preoperative albumin level in serum was identified as significant risk factor for surgical site infection in those who underwent primary resection , and head and neck reconstructive surgery 
 . the present findings also showed that decreased preoperative serum albumin was associated with postoperative complications in patients who underwent oral surgery . together , these characteristics suggest that a low level of albumin in serum is a reliable factor to predict complications in patients undergoing oral surgery . furthermore , it may be possible to reduce the risk of surgical complications by improving their nutritional status 
 . our results also showed that prolonged operation duration and increased blood loss volume were associated with postoperative complications in the evaluated patients . these clinical parameters are dependent on the severity of the surgical procedure and skill of the surgeon . thus , severely invasive surgery and poor surgical skill previous studies identified significant associations of operation time and blood loss with surgical infection in patients who underwent head and neck surgery 




 . in contrast , another report noted no significant relationships between those in head and neck cancer patients 
 . even though it remains controversial whether operation time and blood loss are important risk factors for complications following oral surgery , it is important to minimize blood loss and reduce operation time by improving surgical techniques and therapeutic strategies . evidence has been presented showing that patients with diabetes are at high risk of slow healing and wound infection following an operation 
 . however , it remains undetermined whether those who undergo oral surgery are more likely to have a risk for surgical infection as compared to non - diabetic patients 
 . in some studies of head and neck cancer patients , no significant correlation between diabetes and surgical infection was found 




 . in the present study , univariate but the diabetic patients who participated in our study were properly controlled by antidiabetic drug or insulin administrations during their hospital stay . although long - term glycemic control may have an influence , the effect of diabetes on postoperative complications remains unclear . further investigations are necessary to clarify the effect of diabetes on patients who undergo oral surgery . postoperative oral hygiene is considered necessary for patients who have difficulty with oral cleaning due to surgical damage , as microflora harbored in the oral cavity may be composed of pathogens related to surgical site infection . recently , oral health care has become recognized as essential to decrease postoperative complications in head and neck cancer , as well as other patients with cancer 


 . a few of the evaluated patients received professional oral health care prior to surgery , thus , we were unable to examine the effects of that on postoperative complications . however , we have observed that preoperative oral health care reduces the percentage of postoperative complications in head and neck cancer patients ( unpublished data ) . we consider that professional oral health care can reduce the risk of postoperative complications in cases of oral surgery . the present findings indicate that hypoalbuminemia and prolonged operation duration are significant risk factors for postoperative complications in patients who undergo oral surgery .
objective the objective of this study was to clarify significant risk factors for postoperative complications in the oral cavity in patients who underwent oral surgery , excluding those with oral cancer.material and methods this study reviewed the records of 324 patients who underwent mildly to moderately invasive oral surgery ( e.g. , impacted tooth extraction , cyst excision , fixation of mandibular and maxillary fractures , osteotomy , resection of a benign tumor , sinus lifting , bone grafting , removal of a sialolith , among others ) under general anesthesia or intravenous sedation from 2012 to 2014 at the department of oral and maxillofacial reconstructive surgery , hiroshima university hospital.results univariate analysis showed a statistical relationship between postoperative complications ( i.e. , surgical site infection , anastomotic leak ) and diabetes ( p=0.033 ) , preoperative serum albumin level ( p=0.009 ) , and operation duration ( p=0.0093 ) . furthermore , preoperative serum albumin level ( < 4.0 g / dl ) and operation time ( 120 minutes ) were found to be independent factors affecting postoperative complications in multiple logistic regression analysis results ( odds ratio 3.82 , p=0.0074 ; odds ratio 2.83 , p=0.0086 , respectively).conclusion our results indicate that a low level of albumin in serum and prolonged operation duration are important risk factors for postoperative complications occurring in the oral cavity following oral surgery .