***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: BACKGROUND / AIM Tobacco use reduces the effect of non-surgical periodontal therapy . Host-modulation with low-dose doxycycline ( LDD ) might favour repair and promote an improved treatment response . The aim of this study was to investigate the effect of LDD in smokers on non-surgical periodontal therapy .  MATERIAL AND METHODS This was a parallel arm , r and omized , identical placebo-controlled trial with masking of examiner , care-giver , participant and statistician and 6 months of follow-up . Patients received non-surgical therapy and 3 months of test or control drug . Statistical analysis used both conventional methods and multilevel modelling . RESULTS Eighteen control and 16 test patients completed the study . The velocity of change was statistically greater for the test group for clinical attachment level -0.19 mm/month ( 95 % CI=-0.34 , 0.04 ; p=0.012 ) and probing depth 0.30 mm/month ( 95 % CI=-0.42 , -0.17 ; p<0.001 ) . However , no differences were observed for absolute change in clinical or biochemical markers at 6 months . CONCLUSIONS This study does not provide evidence of a benefit of using LDD as an adjunct to non-surgical periodontal therapy in smokers 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 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 AIM To determine whether adjunctive metronidazole therapy would compensate for the poorer treatment response to scaling and root planing reported in smokers . METHOD A single-blind , r and omised clinical trial of 28 smokers and 56 non-smokers , stratified for periodontitis disease severity and r and omly allocated to 3 treatment groups : ( 1 ) Scaling and root planing using an ultrasonic scaler with local anaesthesia ( SRP ) , ( 2 ) SRP+ metronidazole tabs 200 mg tds for 7 days , ( 3 ) SRP + 2 subgingival applications of 25 % metronidazole gel .  Probing depths ( PD ) and attachment levels ( AL ) were recorded with a Florida probe at baseline , 2 months and 6 months post treatment by a single examiner who was unaware of the treatment modality . Results were analysed for all sites with baseline probing depths equal to or greater than Florida probe recordings of 4.6 mm using analysis of variance . RESULTS Reductions in probing depth at 6 months were significantly less ( p < 0.001 ) in the smokers ( mean 1.23 mm , 95 % confidence intervals = 1.05 to 1.40 mm ) than in the non-smokers ( 1.92 , 1.75 to 2.09 mm ) . Attachment level gains were approximately 0.55 mm and there was no statistically significant difference between smokers and non-smokers . There were no differences in any clinical measure in response to the three treatment regimens at 2 or 6 months for either smokers or non-smokers . A reduction in the proportion of spirochaetes was observed at 6 months which was less in smokers than in non-smokers ( p = 0.034 ) . Multiple linear regression analysis on probing depth at 6 months demonstrated that smoking was a significant explanatory factor ( p < 0.001 ) for poor treatment outcome , whilst the presence or absence of adjunctive metronidazole was not ( p = 0.620 ) . CONCLUSION This study confirms that smokers have a poorer treatment response to SRP , regardless of the application of either systemic or locally applied adjunctive metronidazole BACKGROUND The purpose of this clinical trial is to evaluate the adjunctive clinical effects of the systemic administration of ornidazole ( ORN ) in the full-mouth scaling and root planing ( SRP ) of individuals with moderate-to-advanced chronic periodontitis . METHODS Fifty-eight individuals presenting ≥12 teeth with probing depth ( PD ) ≥4 mm were selected . All participants were instructed on strict oral hygiene measures and were advised to use 0.2 % chlorhexidine mouthwash for 1 week before being allocated to two groups . Thirty participants were r and omly assigned to full-mouth SRP + placebo ( control group ) , and 28 participants were assigned to full-mouth SRP + ORN ( test group ) . The clinical outcomes evaluated were plaque index , gingival index , clinical attachment level ( CAL ) , and PD . RESULTS Fifty participants could be evaluated by ≤6 months . At 6 months , the test group had greater mean reduction ( 2.84 mm ) in PD compared to the control group ( 0.84 mm ) ( P < 0.05 ) , and there was also a greater mean CAL reduction ( 2.92 mm ) in the test group compared to the control group ( 0.92 mm ) ( P < 0.05 ) . CONCLUSION The systemic use of ORN , when used in conjunction with initial periodontal treatment consisting of SRP in adults with periodontitis , achieves significantly better clinical results than initial periodontal treatment alone The present investigation was performed to study the effect of long-term , low dosage tetracycline therapy on advanced periodontal disease in humans . 14 volunteers participated in the trial . Each of the participants had at least 4 pairs of diseased sites around contralateral premolars and incisors with deep pockets and advanced bone loss . The trial extended over a 50-week period and was design ed as a double-blind split-mouth study . A Baseline examination included assessment s of oral hygiene , gingival conditions , probing depth , attachment level and analysis of the composition of the subgingival microbiota in sample s obtained from 8 selected diseased sites . All participants received oral hygiene instruction . In each patient 2 quadrants of the mouth , chosen at r and om , were treated by scaling and root planing . The 2 remaining quadrants were left unscaled . Following the Baseline examination the patients were r and omly distributed into 2 groups of 7 members each . In one of the groups the patients received tetracycline on a daily basis during a 50-week period . The participants of the control group received placebo . Reexaminations were performed 2 , 10 , 20 , 30 and 50 weeks after the Baseline examination . The findings demonstrated that in patients with advanced periodontal disease long-term tetracycline therapy in the absence of scaling result ed in the establishment of a subgingival microbiota almost devoid of motile bacteria and in markedly reduced signs of gingivitis , probing depth and attachment loss . In fact , the alterations observed as a result of tetracycline administration to patients with excellent self-performed plaque control were similar to those obtained by conventional scaling and root planing in the control group 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 The present r and omized , double-masked , placebo-controlled , parallel-arm study examines the impact of adjunctive subantimicrobial-dose doxycycline ( SDD ) on the local inflammatory response through cytokine and chemokine levels in gingival crevicular fluid ( GCF ) sample s from patients with chronic periodontitis . METHODS Forty-six patients with chronic periodontitis received scaling and root planing with or without adjunctive SDD . GCF sample s were collected and clinical parameters including probing depth , clinical attachment level , gingival index , and plaque index were recorded every 3 months for 12 months . GCF tumor necrosis factor-α , interleukin (IL)-6 , IL-4 , IL-10 , IL-13 , IL-17 , macrophage inhibitory protein 1α , macrophage inhibitory protein 1β , monocyte chemoattractant protein 1 , and regulated on activated normal T-cell expressed and secreted protein levels were determined by xMAP multiplex immunoassay . RESULTS Significant improvements were observed in all clinical parameters in both groups over 12 months ( P < 0.0125 ) , whereas the SDD group showed significantly better reduction in gingival index , probing depth , and gain in clinical attachment compared to the placebo group ( P < 0.05 ) . Decrease in IL-6 in the SDD group was significantly higher compared to the placebo group at 6 and 9 months in deep pockets ( P < 0.05 ) , whereas tumor necrosis factor-α was significantly reduced in moderately deep pockets ( P < 0.05 ) . SDD result ed in 
    Output:
    
For the treatment of patients with aggressive periodontitis , systemic antibiotics combined with non-surgical periodontal therapy result ed in a significant additional effect compared to non-surgical therapy alone .
There is a visible trend that showed metronidazole + amoxicillin is the most potent antibiotic combination