***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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    Input: Background and Objective Prospect i ve studies that investigated the influence of surgical and nonsurgical procedures in the recurrence of periodontitis and tooth loss  in periodontal maintenance therapy ( PMT ) programs have not been previously reported . The objective of this study was to evaluate longitudinally the recurrence of periodontitis in regular compliers ( RC ) and irregular compliers ( IC ) individuals undergoing surgical and non-surgical procedures over 5 years in a program of PMT .  Material s and Methods A total of 212 individuals participated in this study .  Full-mouth periodontal examination including bleeding on probing , probing depth , and clinical attachment level were determined at all PMT visits over 5 years . The recurrence of periodontitis was evaluated in RC and IC individuals undergoing surgical and non-surgical procedures in PMT . The influences of risk variables of interest were tested through univariate analysis and multivariate logistic regression . Results Recurrence of periodontitis was significantly lower among RC when compared to IC . Individuals with recurrence of periodontitis and undergoing surgical procedures showed higher probing depth and clinical attachment loss than those who received non-surgical procedures . Recurrence of periodontitis was higher in individual undergoing surgical procedures and irregular compliance during PMT . Conclusions Irregular compliance and surgical procedures in individuals undergoing PMT presented higher rates of recurrence of periodontitis when compared to regular compliant patients undergoing non-surgical procedures Three methods for treatment of periodontal pockets  ( subgingival curettage , modified Widman flap surgery , and pocket elimination ) were applied as a clinical trial to 82 patients . Follow up results over one to five years after the initial treatment are reported . The variations in attachment levels and pocket depth were analyzed statistically as related to methods of treatment and yearly time intervals following the initial treatment . The most favorable results regarding gain or maintenance of attachment levels and reduction of pocket depth were observed interproximally . Subgingival curettage provided the greatest gain in attachment level up to three years postoperatively , but after four to five years there was no significant difference in results following the three methods . The most significant loss of attachment and return of pocket depth occurred on the buccal aspects of the teeth , and the results were not significantly different for the three methods except at the first year of follow up when the attachment level was maintained best after curettage Limited information is available comparing the relative longitudinal effectiveness with respect to tooth type of scaling and root planing alone and scaling and root planing followed by flap procedures . The purpose of this study was to investigate these treatment methods as applied to molar and nonmolar teeth on a longitudinal basis in humans . Seventeen subjects with chronic periodontitis received thorough scaling and root planning as well as oral hygiene instruction . A modified Widman flap was then r and omly performed for one-half of each subject 's dentition . Routine recall prophylaxis and oral hygiene reinforcement were administered postsurgically every 3 to 4 months . Pocket depth and clinical attachment levels were recorded by a single calibrated examiner before therapy and at intervals up to 61/2 years following active treatment . Ten subjects remained as participants after 61/2 years . A paired t test was used to test for the mean difference in pocket depth and clinical attachment level between molar and nonmolar teeth for each treatment method . For pockets initially 4 to 6 mm , the results indicated greater pocket depth and more apical clinical attachment level on molars than nonmolars treated by either method of therapy . For pockets initially greater than or equal to 7 mm there was no difference between pocket depth on molar and nonmolar teeth following scaling and root planing alone . However , there was less overall pocket depth on nonmolars than molars following the flap procedure , indicating a greater effect of pocket reduction on nonmolar than molar teeth with the flap procedure . No difference between tooth types was found for clinical attachment level in pockets initially greater than or equal to 7 mm with either treatment method . Both treatment methods result ed in at least maintenance of pretreatment attachment levels adjacent to molar and nonmolar teeth 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 Eighty-two patients were treated in a split mouth design with coronal scaling ( CS ) , root planing ( RP ) , modified Widman surgery ( MW ) , and flap with osseous surgery ( FO ) which were r and omly assigned to the various quadrants in the dentition . Following phase I and phase II therapy , the patients received supportive periodontal treatment ( SPT ) at 3-month intervals for up to 7 years . Clinical attachment level ( CAL ) was determined initially , post-phase I , post-phase II and prior to each SPT appointment . If a site lost > or = 3 mm of CAL from its baseline , it was classified as a breakdown site . Baselines were the initial exam for sites treated by CS and 10 weeks post-phase II for sites treated by RP , MW , and FO . Data were grouped by probing depth ( PD ) severity at the initial exam and at post-phase II . The breakdown for CS sites was assessed separately from RP , MW , and FO sites because of different baselines and retreatment protocol s. Sites treated by CS had a higher incidence of breakdown than the other therapies through year 1 of SPT . The breakdown incidences/year for RP and MW sites were similar and greater than for FO sites in 1 to 4 mm and 5 to 6 mm PD categories . Breakdown incidence of RP sites was greater than MW sites which was greater than FO sites initially > or = 7 mm . Differences in incidence of breakdown between therapies after recategorizing data by post-phase II PD were the same as above , except no difference was present between RP and MW sites > or = 7 mm . Breakdown incidences were greater in increasing PD severities regardless of when they were categorized . There was no further loss of CAL one year after retreatment in 88 % of sites . Patients with higher breakdown incidences tended to be smokers at the initial exam Eighty-two periodontal patients were treated in a split mouth design with coronal scaling ( CS ) , root planing ( RP ) , modified Widman surgery ( MW ) , and flap with osseous resection surgery ( FO ) which were r and omly assigned to various quadrants in the dentition . Therapy was performed in 3 phases : non-surgical , surgical , and supportive periodontal treatment ( SPT ) < or = 7 years . Clinical data consisted of probing depth ( PD ) , clinical attachment level ( CAL ) , gingival recession ( REC ) , bleeding on probing ( BOP ) , suppuration ( SUP ) , and supragingival plaque ( PL ) . Because of the necessity to exit many CS treated sites due to breakdown , data for CS were reported only up to 2 years . All therapies produced mean PD reduction with FO > MW > RP > CS following the surgical phase for all probing depth severities . By the end of year 2 there were no differences between the therapies in the 1 to 4 mm sites . There were no differences in PD reduction between MW and RP treated sites by the end of year 3 in the 5 to 6 mm sites and by the end of year 5 in the > or = 7 mm sites . FO produced greater PD reduction in > or = 5 mm sites through year 7 of SPT . Following the surgical phase , FO produced a mean CAL loss and CS and RP produced a slight gain in 1 - 4 mm sites . RP and MW produced a greater gain of CAL than CS and FO following the surgical phase in 5 to 6 mm sites , but the magnitude of difference decreased during SPT . Similar CAL gains were produced by RP , MW , and FO in sites > or = 7 mm . These gains were greater than that produced by CS and were sustained during SPT . Recession was produced with FO > MW > RP > CS . This relationship was maintained throughout SPT . The prevalences of BOP , SUP , and PL were greatly reduced throughout the study and were comparable between sites treated by RP , MW , and FO while the CS sites had more BOP and SUP The most common forms of destructive periodontal disease have been thought to slowly and continuously progress until treatment or tooth loss . Recently , data have become available which are inconsistent with this " continuous disease " hypothesis . Data from longitudinal monitoring of periodontal attachment levels and alveolar bone in humans and in animals suggest that periodontal disease progresses by recurrent acute episodes . In addition , rates of attachment loss have been measured in individual sites which are faster than those consistent with the continuous disease hypothesis or slower than those expected from estimates of prior loss rates . To account for these observations , a model of destructive periodontal disease is described in which bursts of activity occur for short periods of time in individual sites . These bursts appear to occur r and omly at periodontal sites throughout the mouth . Some sites demonstrate a brief active burst of destructive periodontal disease ( which could take a few days to a few months ) before going into a period of remission . Other sites appear to be free of destructive periodontal disease throughout the individual 's life . The sites which demonstrate destructive periodontal activity may show no further activity or could be subject to one or more bursts of activity at later time periods . Comparison of monitored loss rates for a year with mean loss rates prior to monitoring suggested that there may be relatively short periods in an individual 's life in which many sites undergo periodontal destruction followed by periods of extended remission . An extension of the r and om disease model is also suggested in which bursts of destructive periodontal disease activity occur with higher frequency during certain periods of an individual 's life The purpose of this study was to record the rate of periodontal disease progression over a 10-year period with respect to individual subject , age and tooth type . 283 subjects , who had undergone a full-mouth radiographic examination in 1974 - 76 and at that time were 25 - 70 years old , were r and omly selected from a larger patient sample for a new radiographic examination in 1985 - 86 . 201 subjects ( 71 % ) agreed to participate . For each respondent , tooth loss over the 10-year period was calculated . The radiographic bone height at the mesial and distal aspect of all teeth was assessed by measuring the distance between the cemento-enamel junction and the bone crest . Difference in periodontal bone height between the 2 examinations was calculated for each tooth site . The results revealed that the mean number of teeth lost over the 10-year period was 3.8 ( SD 4.6 ) . Tooth mortality , expressed as a % of the no. of teeth present at the initial examination , increased with age and varied between 2.9%-28.5 % . In all age groups , molars had the highest and canines the lowest rate of tooth mortality . The frequency of subjects with loss of greater than 10 teeth was highest for the initially 45-year old individuals ( 20 % ) . 7 individuals ( 3 % ) had become edentulous . The mean annual reduction of alveolar bone height varied between 0.07 - 0.14 mm in the age groups 25 - 65 years . The initially 70-year old subjects showed a statistically significant higher annual rate of bone loss ( 0.28 mm ) . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND The aim of the present study was to evaluate and compare the long-term clinical outcomes of erbium-doped : yttrium , aluminum , and garnet ( Er : YAG ) laser-assisted periodontal flap surgery versus conventional treatment with the modified Widman flap procedure . METHODS A total of 146 single-rooted periodontally involved teeth from 25 patients were included in this study . In each patient , left or right maxillary single-rooted teeth were assigned r and omly to one of two groups : group A ( Er : YAG laser ) and group B ( modified Widman flap surgery ) . Er : YAG laser was used to debride the bone pockets , scale the root surface , and trim the periodontal flap . Recession , probing depth ( PD ) , clinical attachment level ( CAL ) , plaque index ( PI ) , gingival index ( GI ) , and bleeding on probing ( BOP ) scores were recorded at baseline and at 3 , 6 , 12 , 24 , 36 , 48 , and 60 months . RESULTS Both treatments result ed in decreases in PD , PI , GI , and BOP , increases in gingival recession , and gains in CAL . PD reduction in group A versus group B was statistically significant at 6 , 12 , 24 , and 36 months ( P < 0.05 ) . Gains in CAL were significantly greater in group A versus group B at 6 , 12 , 24 , and 36 months . BOP scores were significantly lower in group A versus group B at 3 and 6 months ( P < 0.05 ) . All other differences between treatment groups were not statistically significant . CONCLUSIONS Surgical treatment of single-rooted teeth with chronic periodontitis using the Er : YAG laser yields greater PD reduction and gains in CAL for up to 3 years compared to conventional Widman flap surgery . The short-term results obtained with both treatments can be maintained over 5 years Periodontal disease is assessed and its progression is determined via observations on a site-by-site basis . Periodontal data are complex and structured in multiple levels ; thus , applying a summary statistical approach ( i.e. , the mean ) for site-level evaluations results in loss of information . Previous studies have shown the availability of mixed effects modeling . However , clinical ly beneficial information on the progression of periodontal disease during the follow-up period is not available . We conducted a multicenter prospect i ve cohort study . Using mixed effects modeling , we analyzed 18,834 sites distributed on 3,139 teeth in 124 patients , and data were collected 5 times over a 24-month follow-up period . The change in the clinical attachment level ( CAL ) was used as the outcome variable . The CAL at baseline was an important determinant of the CAL changes , which varied widely according to the tooth surface . The salivary levels of periodontal pathogens , such as Porphy 
    Output:
    
The outcomes after periodontal therapy remained stable over time .
Disease progression occurred in a reduced number of sites and patients , mostly associated with poor oral hygiene , poor compliance with SPT , and smoking