Influence of different irrigation protocols on microhardness and flexural strength values of young and aged crown dentin

OBJECTIVE To investigate the effect of different irrigation protocols on microhardness (MH) and flexural strength (FS) values of young and aged crown dentin. BACKGROUND In addition to ageing, root canal irrigation might also affect the mechanical properties of coronal dentin walls. MATERIALS AND METHODS One hundred and twenty dentin bars (2 mm × 2 mm × 8 mm) were obtained from the crowns of extracted, non-caries, human molars of young and older patients (n = 60 bars; average patient ages: 16.7 and 65.4, respectively). Subgroups were formed as follows: 2.5%NaOCl(sodium hypochlorite)+5%EDTA(ethylenediaminetetraacetic acid), 2.5%NaOCl + 15%EDTA, 2.5%NaOCl, 5%EDTA, 15%EDTA and Saline. NaOCl and saline were used for 20 minutes and EDTA solutions for 1 minute. MH values of each sample were measured before and after the irrigation protocols. The same samples were also submitted for FS analysis. The data were statistically analysed. RESULTS Young samples had lower MH values at pre- and post-treatment compared to aged samples (P