Ultrastructural analysis of radicular dentine surface submitted to CO2 laser at different parameters.
BACKGROUND
There are no reported studies comparing different parameter settings of the CO(2) laser and irradiation direction considering their effect on the morphology of radicular dentine surface.


OBJECTIVE
To evaluate the alterations of radicular dentine (cervical, middle, and apical thirds) irradiated with CO(2) laser at different potencies and irradiation directions.


METHODS
Roots of 35 canines were prepared and randomly distributed according to the laser potency: GI: no laser treatment (control) (n = 5); GII, 2 W (n = 10); GIII: 4 W (n = 10); GIV: 6 W (n = 10). Each group (excepting GI) was divided in two subgroups according to the irradiation distance (n = 5): (A) parallel and (B) perpendicular to the root canal walls. The roots were splited longitudinally and analyzed by scanning electron microscopy in a qualiquatitative way. The scores were submitted to Kruskal-Wallis and Dunn's tests.


RESULTS
No significant statistical differences were observed among root canal thirds (P > 0.05). The specimens irradiated with 2 W were statistically different (P < 0.05) from those irradiated with 4 and 6 W, which were statistically similar between themselves (P > 0.05). With 2, 4, and 6 W at in parallel irradiation and 2 W in perpendicular direction, the surface showed a fissured aspect. With 4 W in perpendicular direction and 6 W in parallel and perpendicular direction, surface was modified by laser action and exhibited fused areas.


CONCLUSIONS
The intensity of the effects is dependent on the laser-irradiation dosimetries. Alterations were more intense when higher parameters were used.
School of Dentistry, University of Ribeirão Preto, Ribeirão Preto, Brazil.
S M B
SM
Nomelini
A E
AE
Souza-Gabriel
M A
MA
Marchesan
M D
MD
Sousa-Neto
Y T C
YT
Silva-Sousa
D000818:Animals; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure*; D004285:Dogs; D054020:Lasers, Gas; D008855:Microscopy, Electron, Scanning; D014092:Tooth Root / Q000528:radiation effects* / Q000648:ultrastructure*