EFFECT OF ETCHING TIME AND ACID CONCENTRATION ON MICROMORPHOLOGICAL CHANGES IN DENTIN OF BOTH DENTITIONS

Abstract

Aim: to compare micro morphological changes in primary and permanent dentin after etching with phosphoric acid (20% and 37,5%) for 7 and 15 sec. by SEM. Material and methods: The study included 42 primary and permanent teeth, divided into 8 groups by etching time and acid concentration. Enamel and dentin were removed from the vestibular area and after the expiration of etching time samples were washed with water-air stream and dried with light airflow. From each sample 10 magnified images were made from central vestibular area. The cleaning effect was measured in percentage, as a ratio between the numbers of uncleaned tubules to the total tubules. Results were analyzed with One-way and MANOVA. Post hoc Multiple Comparisons test – SPSS 19 was applied. Results: The proportion of uncleaned tubules in primary teeth was higher than that of permanent teeth at acid concentration of 20%. At a concentration of 37.5% this relationship is reversed. At 7 sec there was a bigger difference between the share of uncleaned tubules for primary and permanent teeth, while at 15 sec this difference virtually disappears. The difference in the proportion of uncleaned tubules between the two acid concentrations at 7 seconds etching is significantly greater compared to the same difference between the two acid concentrations by etching for 15 sec. Conclusion: Effectively removed smear layer and no precipitate was observed in primary teeth even at 7 seconds etching with 37.5% acid.

Keywords

• etching time
• primary dentin
• permanent dentin
• smear layer
• SEM
• peritubular dentin