Methods: A continuous fibroblastic cell line (McCoy cells) was used. All experiments were repeated 5 times. Root surface dentin specimens (25 mm2) were prepared from uniradicular teeth (of non-smoking patients) that were extracted due to severe chronic periodontal disease. Specimens were randomly assigned to two experimental groups, A (cotinine conditioning only) and B (scaling and root planning after cotinine conditioning). All specimens were submitted to the chemical conditioning, which was performed on 24-well plates for 24 hours at 37° C. The cotinine concentrations used were: 0 (negative control), 50ng, 100ng, 500ng and 1 ug/mL. After the 24-hours conditioning period, specimens were washed (3 times) with PBS. B group specimens were submitted to scaling and root planning (single operator, 20 strokes). Then, 2mL of eagle medium containing 1 x 105 cells/mL were added to each well and incubated for 24hours. Specimens were prepared for SEM analysis, and microphotographs obtained by the laboratory technician, who was unaware of the experimental groups. Three independent, calibrated and blind to the experimental groups examiners evaluated microphotographs according to two established index systems.
Results: Analysis was conducted using the classification and regression trees and indicated that the greater cotinine concentration (1ug/mL) led to alteration on morphology on both A and B groups. Cellular density was reduced by cotinine concentrations of 500ng and 1ug/mL, but B specimens presented comparatively greater cell density.
Conclusions: Cotinine treatment on root surfaces may alter cell morphology and density, scaling and root planning these surfaces may reduce the negative effects.