Investigation of roughness, permeability, and bacterial adhesion of dentin surfaces treated with different desensitization methods

Objective: The aim of this study is to evaluate the roughness, permeability and bacterial adhesion of dentin surfaces on which various desensitizing methods are applied in vitro. Method: In this study, 5% NaF (NaF, Enamelast fluoride varnish, Ultradent, USA), CPP-ACP (MI Paste plus, GC Corporation, Tokyo, Japan), Er,Cr:YSGG laser (Waterlase, Biolase, California, USA) and diode laser (Biolase, California, USA) were used in combined forms. One hundred and eight dentin blocks of 5×5×3 mm were prepared from the buccal parts of the root dentin of newly extracted bovine incisors, and these blocks were divided into nine groups according to the desensitization method applied. Surface roughness (SR) was measured with a profilometer. To produce pellicle, dentin samples were coated with artificial saliva and mucin. S. mutans and S. mitis suspensions were added to the samples coated with pellicle. Bacterial suspensions were incubated at 37°C in an atmosphere of 5% CO2 for 24 hours. Bacterial counts were determined as ×108 ml CFU/ml. Bacterial adhesions were visualized using a confocal laser scanning microscope. Dentin permeability was determined using Image J program after imaging with SEM. Statistical analysis was performed using one-way ANOVA and Tukey HSD multiple comparisons (p = 0.05). Results: The control group, which did not apply any desensitizing method, showed the lowest SR values (p<0,05). Except for the CPP-ACP+Er,Cr:YSGG and CPP ACP+Diode groups, the surface roughness change of all groups was statistically significantly higher than the control group (p<0,05). However, in terms of bacterial adhesion, there was no significant difference between the groups in the numbers of bot S. mutans and S. mitis on the samples (p<0,05). All groups significantly reduced the number and diameter of open dentinal tubules (p<0,05). Conclusion: Except for the CPP-ACP+Er,Cr:YSGG and CPP-ACP+Diode groups, it was observed that all groups have significantly higher surface roughness, however, higher surface roughness did not create a significant difference between the groups in the adhesion of S. mutans and S. mitis. In addition, all desensitizing methods applied showed differences in the number and diameter of open dentinal tubules compared to the control group, and showed effectiveness in dentin permeability. Key words: dentin sensitivity, surface roughness, bacterial adhesion, dentin permeability.