Page 39 - Journal of Laser Dentistry 1

Kaitsas V., Olivi G.,

Morphologic changes and smear layer removal on root canal surface after 810 diode laser irradiation: SEM investigation.

Aim.The purpose of this in vitro study was to investigate with SEM observation the ultrastructural morphological changes of the root canal surface after 810-nm diode laser irradiation used at different parameters and delivery modes for the final debridment and decontamination of the root canal.

Material and Methods. Twentyfive, fresh extracted single-root human teeth were used for this study. After a conventional Ni-Ti root-canal rotary instrumentation up to 30/06 crown down technique (Hero 642-MicroMega, Besancon, France) irrigating with 5% sodium hypochlorite (SH) solution each step, the samples were then irradiated laser irradiated: G1(10) 810-nm laser at 2.5 W power in gated mode (10 msec on and 10 msec off) for 5 sec, for three times in 17% ethylenediaminetetraacetic acid (EDTA) wet canal and G2(10) 810-nm laser at 1,5 W power in continuous mode in sodium hypochlorite solution. Two teeth were irradiated in continuous wave three times for 5 sec (at 1,5W) in dry canal (laser control group and other three teeth (control group) were left unlased.

Results. The SEM images revealed debris and smear layer on the root canal surface obscuring the dentin tubules of all the control specimens.

Diode laser promotes morphologic changes of dentin walls and debris removal from root surfaces: when considering different output powers and delivery modes our results

showed that changes varied from smear layer removal to dentine fusion.

The specimens irradiated in gated mode with Diode laser (2,5W) in EDTA wet canal, showed more cleaned surfaces with opened tubules and less smear layer.

Conclusion. These results indicate that the diode laser is useful for removing smear layer and debris from root canal walls when associated with appropriate chelant irrigants.

KEY WORDS: Diode laser, sodium hypoclorite, EDTA, smear layer.

The ability to clean and remove the smear layer and bacterias from the root canal system is the gol of the non-surgical endodontic treatment. Clinically, endodontic techniques use both mechanical instrumentations and chemical irrigants or ultrasonic devices, in the attempt to debride and to decontaminate the root canal system. Studies have shown that their ability to effectively clean and decontaminate all the intraradicular canal space is limited (1,2,3), due to the complexity of the tridimensional root canal system and to the lack of penetration of the chemical irrigants into the lateral canal and tubules that reach only 100 microns (3). Different laser wavelengths demonstrated effective in remarkably reducing the bacterial load from in vitro infected root canals (4,5,6,7). Further studies demonstrated that laser action togheter with commonly used irrigants such as 17% ethylenediaminetetraacetic acid (EDTA) or 10% citric acid and 5% sodium hypoclorite (8), improve the synergy action of both the debridement and bactericidal effect. The purpose of this in vitro study was to