Deep disinfection and tubular smear layer removal with Er:YAG using photon-induced photoacoustic streaming (PIPS) contra laser-activated irrigation (LAI) technics

This in vitro laboratory study assessed the efficacy of the laser in deep disinfection and smear layer removal with 2940-nm erbium:yttrium aluminum garnet (Er:YAG) laser. The purpose was to evaluate the efficacy of a conical and stripped Er:YAG tip using PIPS (photon-induced photo acoustic streaming) in root canals compared with end firing Preciso tip using LAI (laser-activated irrigation). Thirty extracted single-rooted upper teeth were divided in three groups for smear layer removal: using PIPS and Preciso with the third as the control group. After irradiation methods with different erbium tips, the roots were longitudinally split for SEM observation. The root canals were then scanned separately in each specimen in all three thirds—coronal, middle, and apical. The remaining smear layer was evaluated with the Hülsmann score (Hülsmann et al., J Endod 23:301–306, 1997). In the coronal third of the canal, both the PIPS and the Preciso group scored significantly better when equaled with the control group. In the middle third, the PIPS group got the smallest score, which was meaningfully different from that of the Preciso and the control groups. Preciso scored higher in the apical third, in comparison to the control group and PIPS group. Statistically significant alterations were found. This SEM study showed that Er:YAG used with PIPS and Preciso tips, which generate cavitation in the irrigant, did not enhance the removal of the smear layer from dentin tubules from the apical part of a straight root canal when used only with saline solution as irrigant.