***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Alveolar osteitis ( AO ) is a common complication after third molar surgery . One of the most studied agents in its prevention is chlorhexidine ( CHX ) , which has proved to be effective . Objectives : The aim of this r and omized double-blind clinical trial was to evaluate the efficacy of 0.2 % bioadhesive chlorhexidine gel placed intra-alveolar in the prevention of AO after the extraction of m and ibular third molars and to analyze the impact of risk factors such as smoking and oral contraceptives in the development of AO . Study Design : The study was a r and omized , double-blind , clinical trial performed in the Ambulatory Surgery Unit of Hospital Vall d’Hebron and was approved by the Ethics Committee . A total of 160 patients r and omly received 0.2 % bioadhesive gel ( 80 patients ) or bioadhesive placebo ( 80 patients ) . Results : 0.2 % bioadhesive chlorhexidine gel applied in the alveolus after third molar extraction reduced the incidence of dry socket by 22 % compared to placebo with differences that were not statistically significant . Smoking and the use of oral contraceptives were not related to higher incidence of dry socket .  Female patients and the difficulty of the surgery were associated with a higher incidence of AO with statistically significant differences . 0.2 % bioadhesive chlorhexidine gel did not produce any of the side effects related to chlorhexidine rinses . Conclusions : A 22 % reduction of the incidence of alveolar osteitis with the application of 0.2 % bioadhesive chlorhexidine gel compared to placebo with differences that were not statistically significant was found in this clinical trial . The lack of adverse reactions and complications related to chlorhexidine gel supports its clinical use specially in simple extraction s and adds some advantages compared to the rinses in terms of duration of the treatment and reduction of staining and taste disturbance . Key words : Alveolar osteitis , dry socket , chlorhexidine bioadhesive gel , m and ibular third molar surgery Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more PURPOSE The main purpose of the present investigation was to determine whether intra-alveolar chlorhexidine ( CHX ) gel is an effective preventative treatment for alveolar osteitis ( AO ) , as has been strongly suggested by previous investigators . Another goal was to evaluate whether there is a correlation between the use of analgesics during the postoperative week and the development of AO , a correlation that could be a supplement to the commonly used diagnostic criteria for AO . MATERIAL S AND METHODS A double-blinded r and omized study was performed to assess whether intra-alveolar administration of CHX decreases AO . To achieve this objective , the extraction and postoperative course of 100 impacted m and ibular third molars were studied . Ninety-seven percent of teeth operated on had a diagnosed pathology . The extraction alveoli were treated with CHX or placebo . The intake of analgesics was recorded for 7 days after the operation . RESULTS Statistically important differences in AO between the control and experimental groups were not found . The intake of analgesics reflected the occurrence of AO with a high degree of importance . CONCLUSION The present study did not verify that application of CHX gel improves healing after removal of impacted third molars . The patients ' postoperative analgesic intake reflected the development of AO OBJECTIVE To determine the efficacy of intra-alveolar administration of chlorhexidine ( CHX ) gel in reducing the frequency of alveolar osteitis ( AO ) after impacted m and ibular third molar surgery . STUDY DESIGN A r and omized control trial study . PLACE AND DURATION OF STUDY Department of Oral and Maxillofacial Surgery , Armed Forces Institute of Dentistry , Rawalpindi , Pakistan , from January to December 2007 . METHODOLOGY One hundred patients including 65 males and 35 females with the age range 18 - 40 years were divided in two equal groups ( 50 each in the CHX and the control groups ) . Surgical removal of impacted m and ibular third molar was carried out and after surgery CHX gel was placed into the alveolus of CHX group . Patients were followed at the first , second and third postoperative days . A proforma indicating presence or absence of pain , blood clot disintegration , halitosis and AO was filled for each patient . Frequencies and percentages were calculated for qualitative data . Chi-square test was applied to compare both subgroups . RESULTS Eighteen patients ( 18 % ) were diagnosed with AO ( 11 males and 7 females ) . Out of these 18 cases , 14 ( 28 % ) were found in control group ( 9 males and 5 females ) , while 4 cases ( 8 % ) in the CHX group ( 2 males and 2 females ) . This was statistically significant p=0.017 . CONCLUSION Single application of CHX gel was effective in reducing frequency of AO following m and ibular third molar surgery Alveolar osteitis ( dry socket ) continues to be a frequent sequela of third molar surgery .  Chlorhexidine 0.12 % used as an oral rinse has been reported to reduce the incidence of dry socket . This study compares the effectiveness of 0.12 % chlorhexidine used as a preoperative rinse and immediate post extraction irrigant with 1 ) similarly used 0.05 % cetylpyridium , preoperative chlorhexidine rinse and post extraction saline irrigation , and 2 ) only post extraction irrigation with normal saline in the reduction of alveolar osteitis in m and ibular third molar extraction s. The results indicate that chlorhexidine and cetylpyridium were no more effective in the reduction of alveolar osteitis than post extraction irrigation with normal saline This nonr and omized prospect i ve study was conducted in a private practice setting to determine the effect of a 0.12 % chlorhexidine gluconate rinse ( Peridex , Proctor and Gamble , Cincinnati , Ohio ) on the incidence of  dry socket after removal of impacted m and ibular third molars . Over a 3-year period , 371 patients ( total of 654 impacted m and ibular third molars ) received either no treatment ( group 1 ) , 2 weeks of twice daily Peridex rinse postsurgery ( group 2 ) , or one rinse presurgery ( group 3 ) . The group that used Peridex twice daily for 2 weeks after surgery ( group 2 ) showed a significant reduction ( 56 % ) in the incidence of dry socket when compared with either the group that did not rinse ( group 1 ) or the group that rinsed only once just before surgery ( group 3 ) . The incidence of dry socket was higher in smokers and in females who used oral contraceptives . Twice daily use of Peridex for 2 weeks also yielded significant reductions in dry socket in smokers , nonsmokers , and in females who did not use oral contraceptives . Results from this study demonstrate that the use of Peridex for 2 weeks after surgery is effective in prevention of dry socket after surgical extraction of impacted molars AIMS To assess the effects of intra-alveolar application of chlorhexidine gel on the incidence of alveolar osteitis ( dry socket )  and the severity of postsurgical pain .  METHODS A total of 160 impacted m and ibular third molars were extracted in 80 patients enrolled in this trial . In each subject , a socket was r and omly selected and packed to the crest of the alveolar ridge with a gelatin sponge dressing saturated in 0.2 % chlorhexidine gel . The contralateral socket was packed with a dry dressing as the placebo . None of the included patients took antibiotics or analgesics . The occurrence of dry socket and patients ' pain levels were assessed at the first and third postoperative days . The data were analyzed using Spearman correlation coefficient , McNemar , Wilcoxon , and chi-square tests . RESULTS Chlorhexidine gel significantly reduced dry socket incidence from 32.6 % to 11.3 % ( P ≤ .001 [ McNemar and chi-square ] , absolute risk reduction = 21.2 % , relative risk reduction = 65.4 % , odds ratio = 0.263 , relative risk = 0.345 ) . It also significantly relieved postoperative pain on both sides in all the patients ( P ≤ .001 [ Wilcoxon ] ) and also in the 54 subjects who did not develop dry socket ( P ≤ .001 [ Wilcoxon ] ) . CONCLUSIONS Besides decreasing the incidence of dry socket  , chlorhexidine gel can reduce postsurgical pain in patients with and without dry socket PURPOSE Chlorhexidine is a good prophylactic agent for post- extraction dry socket alveolitis . The bio-adhesive 0.2 % chlorhexidine gel could improve this action since its intra-alveolar positioning would allow a more direct action on the alveolus and more prolonged action of the medication . MATERIAL S AND METHOD We present a single blind , r and omised study on 30 patients to evaluate the efficacy of the bio-adhesive 0.2 % chlorhexidine gel , placed only once within the alveolus , on the reduction of the incidence of impacted third molar post- extraction dry socket alveolitis  and its post-operative effects on patients . RESULTS A reduction of 42.65 % in the occurrence of alveolitis and a more favourable post-operative period in the experimental group was observed . In the control group , the appearance of alveolitis was 30.76 % opposite to 17.64 % in the experimental group . CONCLUSIONS The bio-adhesive 0.2 % chlorhexidine gel , applied only once after the extraction of impacted third molars , seems to be an appropriate option for the reduction of alveolitis . It improves the buccal aperture and oedema in the post-operative period , although further double blind studies with larger sample s are necessary PURPOSE Chlorhexidine ( CHX ) is an antimicrobial agent used in the prevention of tooth decay , periodontal disease , and post extraction alveolar osteitis ( AO ) . Recently , a bioadhesive gel to deliver the active substance , CHX , was introduced . The intra-alveolar placement of the bioadhesive gel allows a more direct and prolonged therapeutic effect of CHX , which is useful in the prevention of AO after extraction of impacted third molars . The intra-alveolar application of the bioadhesive CHX gel in patients with bleeding disorders may increase the risk of postoperative bleeding complications . Inversely , bleeding disorders might influence the efficacy of CHX for AO prevention . The purpose of the present study was to evaluate the effectiveness of the bioadhesive 0.2 % CHX gel in reducing the incidence of impacted third molar post extraction AO in patients with bleeding disorders . MATERIAL S AND METHODS We performed a double-blind , r and omized , parallel-group study of 38 patients with bleeding disorders . The experimental group ( n = 14 ) was treated with bioadhesive 0.2 % CHX gel applied intraoperatively once after surgical removal of the third molar . The control group ( n = 24 ) was treated in an identical fashion with placebo gel . RESULTS We observed a 57.15 % reduction in the incidence of AO in the experimental group . The control group had a 17 % incidence of AO and the experimental group had a 7 % incidence of AO ( P = .402 ) . Bleeding complications occurred in 21 % of the experimental group compared with 29 % of the control group ( P = .601 ) . CONCLUSIONS As described in previous studies , the single intra-alveolar application of the bioadhesive 0.2 % CHX gel in an intraoperative fashion seems to reduce the incidence of AO after removal of impacted third molars in patients with bleeding disorders . On the basis of the reported percentage of bleeding complications , the routine use of postoperative local hemostatic measures is recommended 
    Output:
    
Conclusion This meta- analysis suggests that CHX gel is superior to a placebo in reducing the incidence of alveolar osteitis after m and ibular third molar extraction