title: Long-term stability of periodontal conditions achieved following guided tissue regeneration with bioresorbable membranes: case series results after 6-7 years.
abstract: OBJECTIVE
  To evaluate the results of guided tissue regeneration (GTR) treatment of intrabony defects with bioresorbable membranes after 6-7 years, and to disclose factors that may influence the long-term outcome of the treatment.
  
  
  METHODS
  Twenty-five defects in 19 patients were treated by means of polylactic acid/citric acid ester copolymer bioresorbable membranes. At baseline and after 1 and 6-7 years, the following parameters were recorded: (1) probing pocket depth (PPD), (2) gingival recession (REC), (3) probing attachment level (PAL)=PPD+REC, (4) presence/absence of plaque (PI), (5) presence/absence of bleeding on probing (BOP). Smoking habits and frequency of dental-control visits were also recorded. Significance of differences between categorical variables was evaluated with McNemar's test, and between numerical variables with the t-test for paired observations. Generalized linear models were constructed to evaluate the influence of various factors on PAL gain and PPD changes from 1 to 6-7 years. Association of smoking, frequency of dental controls, oral hygiene, and BOP with sites losing > or =2 mm in PAL was evaluated with Fisher's exact test.
  
  
  RESULTS
  At baseline, a mean PPD of 8.7+/-1.1 mm and a mean PAL of 9.8+/-1.5 mm was recorded. Statistically significant clinical improvements were observed at 1 and 6-7 years after GTR treatment. An average residual PPD of 3.8+/-1.1 mm and a mean PAL gain of 3.8+/-1.4 mm were observed after 1 year. After 6-7 years the corresponding values were 4.7+/-1.3 and 3.6+/-1.4 mm, respectively. There were no statistically significant differences between the 1- and the 6-7-year values. At the 6-7-year control, only 16% of the sites had lost > or =2 mm (maximum 3 mm), of the PAL gain obtained 1 year after GTR treatment. None of the sites had lost all of the attachment gained 1 year after treatment. Smoking, frequency of dental controls, oral hygiene, and BOP did not seem to influence the change of PPD and PAL gain, or the stability of PAL gain (i.e. losing PAL or not) from 1 to 6-7 years from treatment.
  
  
  CONCLUSIONS
  Clinical improvements achieved by GTR treatment of intrabony defects by means of bioresorbable membranes can be maintained on a long-term basis.
authors.affiliation: Department of Periodontology and Oral Gerontology, Royal Dental College, Aarhus University, Denmark. stavropoulos@odont.au.dk
authors.forename: Andreas
authors.initials: A
authors.lastname: Stavropoulos
authors.forename: Thorkild
authors.initials: T
authors.lastname: Karring
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D016301:Alveolar Bone Loss / Q000601:surgery*; D016009:Chi-Square Distribution; D019343:Citric Acid; D005260:Female; D005500:Follow-Up Studies; D016557:Guided Tissue Regeneration, Periodontal / Q000379:methods*; D006801:Humans; D019344:Lactic Acid; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008567:Membranes, Artificial; D019647:Oral Surgical Procedures; D010512:Periodontal Index; D011091:Polyesters; D011108:Polymers
chemical_list: D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D019343:Citric Acid; D019344:Lactic Acid; C033616:poly(lactide)