A Comparative ex-vivo Study of Effects of Different Irrigation Protocols with/without Laser Activation on the Root Dentine's Micro-Hardness

To compare the effects of different irrigation protocols, with/without laser activation, on the radicular dentine's micro-hardness. Eighty-two human extracted premolars were decoronated and divided into 7 groups. Roots were longitudinally split into two halves. The micro-hardness was measured for one half before and after irrigation protocols. The groups were; G1: MTAD without laser-activation, G2: MTAD with laser-activation, G3: sodium-hypochlorite (SH) with laser-activation, G4: SH then EDTA with laser-activation, G5: SH then MTAD with laser-activation, G6: SH without laser-activation. G7: distilled water (control). In the two-irrigants groups G4 and G5), samples were irrigated first with SH then with MTAD or EDTA irrigants, which were activated by the laser. The difference between the before- and after-irrigation micro-hardness was calculated to obtain the micro-hardness difference. Data were analyzed using the Paired Sample-t and Two-ways ANOVA tests at P=0.05. Overall, the mean dentine's micro-hardness after-irrigation (103.1) was lower than before-irrigation (116.1) (P