Smoking impairs root coverage: clinical and histological study in humans

Objectives: The aim of this study was to evaluate the outcomes of a coronally positioned flap associated with the subepithelial connective tissue graft (CPF + SCTG) for root coverage in smokers and non-smokers, analyzing clinical parameters and graft vascularization patterns between groups.

Methods: Twenty-three patients, 11 smokers, and 12 non-smokers were selected. Each patient had one Miller Class I or II recession in non-molar teeth. Clinical measurements of probing depth (PD), relative clinical attachment level (RCAL), gingival recession (GR) and width of keratinized tissue (KT) were determined at baseline, 6 and 12 months post-operative examinations. The recessions were surgically treated with CPF + SCTG. A portion of this graft was prepared for immunohistochemistry. Blood vessels were identified and counted by co-expression of Factor-VIII related antigen stained endothelial cells.

Results: There was no statistically significant differences (Mann Whitney U Test, p>0.05) in the mean preoperative parameters. Intragroup analysis (Wilcoxon Signed Ranks Test, p<0.05) showed that after 6 and 12 months there was gain in RCAL, decrease in GR and an increase in KT for both groups, while changes in PD were not statistically significant. Analysis between groups (Mann Whitney U Test) demonstrated that smokers had less root coverage than non-smokers after 6 (58.02 ± 19.75 % versus 83.35 ± 18.53 %, p=0.01) and 12 months (52.20 ± 15.73 % versus 85.23 ± 13.99 %, p=0.00). Furthermore, after 1 year, smokers had higher GR (1.69 ± 0.73 mm versus 0.47 ± 0.46 mm, p=0.00) and RCAL (10.37 ± 1.29 mm versus 8.88 ± 1.16 mm, p=0.01) than non-smokers. Histomorphometry of the donor tissue revealed blood vessel density of 47.25 ± 15.20 vessels/200x field for non-smokers, and of 35.18 ± 11.35 vessels/200x field for smokers (p=0.04).

Conclusion: smoking limits and jeopardizes root coverage after coronally positioned flaps associated with subepithelial connective tissue grafts.