title: Smoking affects the outcome of guided tissue regeneration with bioresorbable membranes: a retrospective analysis of intrabony defects.
abstract: OBJECTIVE
  To disclose factors that may influence the results of guided tissue regeneration (GTR) treatment in intrabony defects with bioresorbable membranes.
  
  
  METHODS
  Forty-seven intrabony defects in 32 patients were treated by means of polylactic acid/citric acid ester copolymer bioresorbable membranes. At baseline and after 1 year, 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) and (6) intrabony component (IC) configuration (i.e. primarily presence of one, two, or three bone walls). Occurrence of membrane exposure and smoking habits 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 after 1 year, including in the analysis only one defect per patient (i.e. 32 defects) chosen at random. Odds ratios were calculated using the Mantel-Haenszel method. Differences between smokers and non-smokers were evaluated by means of Pearson's chi2 and Student's t-test for non-paired observations.
  
  
  RESULTS
  At baseline, a mean PPD of 8.6+/-1.1 mm and a mean PAL of 9.8+/-1.6 mm was recorded. Statistically significant clinical improvements were observed 1 year after GTR treatment. An average residual PPD of 3.7+/-1.1 mm and a mean PAL gain of 3.8+/-1.5 mm were recorded. IC configuration and exposure of the membrane did not seem to influence the results, while a negative effect of smoking on the clinical parameters was observed. Smokers gained approximately 1 mm less in PAL than non-smokers (3.2+/-1.4 versus 4.3+/-1.3, respectively; p=0.03) and had approximately seven times less chances to gain 4 mm in PAL as compared with patients who did not smoke (odds ratio: 0.15). PPD reduction was less pronounced in smokers than in non-smokers (4.5+/-0.7 versus 5.5+/-0.7, respectively; p<0.01), resulting in somewhat deeper residual PPD in smokers than in non-smokers (3.6+/-1.0 versus 3.4+/-1.1; p>0.05).
  
  
  CONCLUSIONS
  Smoking impairs the healing outcome of GTR treatment of intrabony defects with bioresorbable membranes.
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: Nikolaos
authors.initials: N
authors.lastname: Mardas
authors.forename: Federiko
authors.initials: F
authors.lastname: Herrero
authors.forename: Thorkild
authors.initials: T
authors.lastname: Karring
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D016301:Alveolar Bone Loss / Q000601:surgery*; D001861:Bone Regeneration; D016009:Chi-Square Distribution; D019343:Citric Acid; D005260:Female; D016557:Guided Tissue Regeneration, Periodontal / Q000379:methods*; D006801:Humans; D019344:Lactic Acid; D016014:Linear Models; D008297:Male; D008567:Membranes, Artificial; D016017:Odds Ratio; D019647:Oral Surgical Procedures / Q000379:methods; D010512:Periodontal Index; D011091:Polyesters; D011108:Polymers; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects*; D016896:Treatment Outcome
chemical_list: D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D019343:Citric Acid; D019344:Lactic Acid; C033616:poly(lactide)