***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: AIM The aim of this study was to evaluate the clinical and microbiological effects of scaling and root planing ( SRP ) alone or combined with metronidazole ( MTZ ) or with MTZ and amoxicillin ( AMX ) in the treatment of smokers with chronic periodontitis . METHODS A double-blind , placebo-controlled , r and omized clinical trial was conducted in 43 subjects who received SRP alone ( n=15 ) or combined with MTZ ( 400 mg 3 x per day , n=14 ) or with MTZ+AMX ( 500 mg 3 x per day , n=14 ) for 14 days . Clinical and microbiological examinations were performed at baseline and 3 months post-therapy . Subgingival sample s were analysed by checkerboard DNA-DNA hybridization . RESULTS Subjects receiving MTZ+AMX showed the greatest improvements in mean probing depth and clinical attachment level . Both antibiotic therapies led to additional clinical benefits over SRP alone in initially shallow , intermediate , and deep sites . The SRP+MTZ+AMX therapy led to the most beneficial changes in the subgingival microbial profile . These subjects showed significant reductions in the mean counts and proportions of periodontal pathogens such as Tannerella forsythia , Porphyromonas gingivalis and Treponema denticola , and the greatest increase in proportions of host-compatible species . CONCLUSION Significant advantages are observed when systemic antibiotics are combined with SRP in the treatment of smokers with chronic periodontitis . The greatest benefits in clinical and microbiological parameters are achieved with the use of SRP+MTZ+AMX The aim of the present study was to analyze the effect of systemic antimicrobial therapy and mechanical plaque control in patients with recurrent periodontal disease . 9 patients volunteered for the combined therapy . At a baseline examination they were r and omly distributed into 2 groups , one given tetracycline therapy for 2 weeks and the other metronidazole therapy for 1 week . A mechanical plaque control program comprising oral hygiene training , professional cleaning of all teeth and subgingival debridement at diseased sites was carried out at the baseline examination and at all recall visits , i.e. once every month during the first 6 months and then after 9 , 12 , and 18 months . The results demonstrated clinical ly and microbiologically that a combination of an initial antimicrobial and a continuous systematic mechanical plaque control program may be a valuable therapeutic approach in a strictly selected group of refractory patients . Recurrent periodontal lesions which still displayed severe inflammation despite renewed conventional therapy showed a marked reduction in probing depths , bleeding and suppuration from the pockets , and further , a reduced presence of spirochetes and motile rods during the trial . The results indicate that the level and longevity of success is also related to whether or not self-performed oral hygiene measures are sufficiently carried out . No superior effect of the combined program could be observed in cooperating patients receiving tetracycline as compared with those given metronidazole Aim Find the periodontal treatment that best maintained clinical results over time evaluated by changes in pocket depth ( PD ) and clinical attachment level ( CAL ) . Methods 229 patients with chronic periodontitis from USA ( n=134 ) and Sweden ( n=95 ) were r and omly assigned to eight groups receiving 1 scaling+root planing ( SRP ) alone or combined with 2 surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole ( MET ) ; 3 SURG+local tetracycline ( TET ) ; 4 SURG ; 5 AMOX+MET+TET ; 6 AMOX+MET ; 7 TET ; and 8 SURG+AMOX+MET+TET . Antibiotics were given immediately after SRP .  Plaque , gingival redness , bleeding on probing , suppuration , PD , and CAL were recorded at baseline and after 3 , 6 , 12 , 18 , and 24 months . Treatment effects were evaluated by linear multilevel regression and logistic multilevel regression models . We considered only data from sites with a baseline PD of at least 5 mm of 187 patients completing the study . Results Surgically treated patients experienced most CAL loss . Adjunctive therapy including SURG was most effective in reducing PD . Combining SURG with AMOX , MET , and TET gave significant clinical benefits . Past and current smoking habits were significant predictors of deeper PD . Only current smoking was a significant predictor of CAL loss . Bleeding , accumulation of plaque , gingival redness , and suppuration were significant predictors of further CAL loss and deeper PD . Conclusions Both surgical and non-surgical therapies can be used to arrest chronic periodontitis . SURG+AMOX+MET+TET gave best maintenance of clinical results Periodontitis , a common cause of tooth loss in adult population s , is an inflammatory response to the overgrowth of anaerobic organisms such as spirochetes and bacteroides and , in some cases , micro-aerophilic organisms in the subgingival plaque . In the present investigation , using a double-blind clinical design , we sought to determine whether 1 week of metronidazole treatment plus debridement of the tooth surfaces was superior to 1 week of placebo treatment plus debridement ( positive control ) in reducing the subsequent amount of periodontal surgery given to the patients . Thirty-nine patients were r and omly assigned to either the metronidazole or placebo ( positive control ) groups . All patients were given the necessary scaling and root planing and were unsupervised in their usage of the medication . After the completion of this treatment , they were reexamined and it was found that the metronidazole regimen caused a significant reduction in surgical needs of about 5 teeth per patient compared to the positive control ( difference before and after treatment 8.3 + /- 6.8 teeth metronidazole versus 2.9 + /- 4.8 positive control , P = 0.007 ) . The difference between groups was maintained during the 2 to 3 years ' recall period . Metronidazole had a significant effect on the site specific reduction of spirochetes : 90 % of the sites in the metronidazole group versus 64 % in the positive-control group had a decrease in the percentage of spirochetes ( P less than 0.05 ) . We conclude that systemic metronidazole given 250 mg tid for 7 days in conjunction with debridement of the tooth surfaces can significantly reduce the need for periodontal surgery compared to the st and ard regimen which included only debridement BACKGROUND AND OBJECTIVE The periodontal region is a source of gram-negative bacterial infection . The pathogens involved have recently also been demonstrated in atheromatous plaques . They may increase the risk of myocardial infa rct ion . In this study a strategy for eradicating periodontal bacteria and thus healing in patients with periodontal pockets and advanced destruction of alveolar bone was examined . PATIENTS AND METHODS Initial periodontal status was documented in 36 patients with periodontitis ( 24 women , 12 men ) who were then r and omly assigned to one of three groups . Those in two of the groups were given either metronidazole or doxycycline orally as adjuvant treatment , while the third group received no antibiotics . Patients in all groups were treated according to a two-step procedure . In step 1 , extensive supra- and subgingival plaques and concrements were removed . In step 2 , root debridement and /or closed curettage of all pockets was undertaken in one visit , and the antibiotic given to the patients in groups 1 and 2 . Results were assessed 3 weeks after the first step and 6 months , 2 and 4 years after step 2 . RESULTS The initial examination at 3 weeks revealed significant changes in all three groups with regard to the incidence of plaque and sulcus bleeding , but not regarding probing depth and attachment level . However , there were significant changes in probing depth and attachment level in all groups after step 2 . Periodontal attachment was significantly improved at 2 and 4 years in the patients on metronidazole , but not those on doxycycline or no antibiotics . The greatest decrease in bleeding tendency was recorded in the metronidazole group . This group also had the greatest gain of new alveolar bone compared with the other two groups . Complete eradication of Porphyromonas gingivalis and Actinobacillus ( Hemophilus ) actinomycetemcomitans , important pathogenic bacteria that may have an atherogenic action , was obtained only in patients on metronidazole . CONCLUSION The tissue-sparing two-step procedure brought about good clinical and radiological results , which can be significantly bettered by the addition of metronidazole , achieving eradication of pathogens involved in periodontal disease AIMS The objective of this study was to investigate the effect of the systemic administration of metronidazole and amoxicillin as an adjunct to initial periodontal therapy in patients with moderate to severe chronic periodontitis . METHODS AND MATERIAL S This r and omized , double blind , placebo controlled parallel study involved 50 adult patients with untreated periodontitis who were r and omly assigned to receive either a full-mouth scaling and root planing along with systemic metronidazole and amoxicillin ( T group ) or scaling and root planing with a placebo ( P group ) . Clinical measurements including probing depth ( PD ) , clinical attachment levels ( CAL ) , Plaque Index ( PI ) , and Bleeding Index ( BI ) were recorded at baseline and six to eight weeks after therapy . The deepest pocket was selected and sample s for microbiological testing were taken . Patients received coded study medications of either 500 mg amoxicillin in combination with 250 mg metronidazole or an identical placebo every eight hours for seven days following scaling and root planing . RESULTS There was a significant change in PD ( P=0.0001 ) , CAL ( P=0.00001 ) , PI ( P<0.05 ) , and BI ( P<0.05 ) in the T group compared to the placebo group after therapy . Parallel to the clinical changes , treatment significantly reduced the number of Actinobacillus actinomycetemcomitans ( Aa ) , Porphyromonas gingivalis ( Pg ) , and P. intermedia ( Pi ) compared with baseline in the T group ( P=0.003 , 0.021 and 0.0001 , respectively ) . However , in the P group only the Pi colony count was reduced significantly ( P=0.0001 ) . After therapy , there was a significant difference between the T and P groups in the number of patients negative for Aa , Pg , and Pi ( Pv = 0.033 ) . CONCLUSIONS The significant differences between treatment and placebo groups are in line with other studies and support the considerable adjunctive benefits of the combination of amoxicillin and metronidazole in the treatment of chronic periodontitis BACKGROUND AND AIM Several studies have reported adjunctive benefits to scaling and root planing ( SRP ) of systemic amoxycillin and metronidazole in the treatment of periodontal diseases . To date no comparisons have been made of these antimicrobials alone or in combination . The aim of this study was to compare the adjunctive benefits to SRP of amoxycillin and metronidazole alone and combined . METHODS 66 subjects < 46 years of age with advanced chronic periodontal disease participated in this r and omised , double blind , 4 parallel treatment group design ed study . All subjects received quadrant SRP and then were prescribed amoxycillin capsules ( 250 mg ) and metronidazole tablets ( 200 mg ) ( AM ) or lactate capsules and metronidazole ( PM ) or amoxycillin and calcium lactate tablets ( AP ) or lactate and calcium lactate ( PP ) . All medication was 3 of each per day for 7 days . Subgingival plaque sample s were obtained and probing depth ( PD ) , loss of attachment ( LOA ) , bleeding on probing ( BOP ) , suppuration ( SUPP ) and plaque ( DEP ) were recorded pre-treatment , 1 , 3 and 6 months post-treatment . RESULTS Final group sizes were : AM=15 , PM=16 , AP=16 and PP=15 . PD improved in all groups . Treatment effects were highly significantly different and always greatest in the AM and least in the PP groups . Benefits of PM and AP over PP were also noted . LOA improved in all groups and showed the same highly significant treatment differences , again favouring AM . BOP improved in all groups , particularly in AM compared to the other groups . SUPP improved in all groups and was virtually eradicated in AM with differences among treatments highly significant . DEP changed little in any group and there were no significant differences among groups . Microbiological data showed significant differences in favour of AM compared to PP and PM for total aerobes and anaerobes at 1 month . P. intermedia counts were always lower in active groups compared to PP and reached significance for AM and AP at 1 month and AM and PM at 3 months . CONCLUSION The significant differences among treatment groups and the overall trend in the data , in line with other studies , support the considerable adjunctive benefits to SRP of amoxycillin and metronidazole combined in the treatment of advanced chronic periodontal disease Considerable data have accumulated which suggest that some or most forms of periodontal disease are specific , albeit chronic , bacteriological infections ( 1 , 2 ) . In most instances the plaque flora removed from infiamed sites are dominated by anaerobic organisms such as spi-rochetes , bacteroides and eubacterium species ( 1^ ) . In some instances , the microaerophilic organism Actinobacil-lus actinom 
    Output:
    
Conclusion With the performed statistical approach , a clear benefit in terms of an enhanced chance for pocket closure by co-administration of the combination of amoxicillin and metronidazole as an adjunct to non-surgical mechanical periodontal therapy has been shown .
However , data calculation failed to show a benefit regarding the possible avoidance of surgical interventions