The sealing ability of an epoxy resin root canal sealer after Nd:YAG laser irradiation of the root canal.
OBJECTIVE
To evaluate ex vivo the effect of Nd:YAG laser irradiation with and without black ink on instrumented root canal walls, and the degree of both coronal and apical microleakage of filled root canals.


METHODS
Seventy-two single-rooted teeth were instrumented up to a size 40 K-file, and then divided into six groups of 10 teeth: groups 1 and 4 remained unlased and acted as control groups, groups 2 and 5 were treated with a Nd:YAG laser (Fidelis Plus, Herzele, Belgium), groups 3 and 6 were treated with a laser and black ink; the remaining 12 teeth served as positive and negative controls. The laser was operated at 1.5 W, 15 Hz, four times for 5 s with a 20-s interval. Groups 4-6 were filled using cold lateral condensation of gutta-percha and AH26. After storage in water for 48 h at 37 degrees C, through-and-through leakage (L in microL day-1) was measured for 48 h under a pressure of 1.2 atm using a fluid transport model and recorded as L=0 (L1), 0<L<or=10 (L2), L>10 (L3). After the assessment of leakage with the fluid transport model, the teeth were immersed in rhodamine B solution for 48 h at 37 degrees C. Apical and coronal dye leakage was scored after longitudinal splitting of these teeth. All teeth of groups 1-3 were split longitudinally and observed under SEM for evaluation of remaining smear layer.


RESULTS
Through-and-through leakage was only observed in the group lased with black ink (two samples-L2). Apical and coronal dye leakage was observed in all groups; there were no statistically significant differences amongst the three experimental groups. The through-and-through leakage, measured with the fluid transport model in two teeth of group 6, was confirmed in the dye leakage test (rhodamine B dye was observed along the total length of the root filling). There was evidence of melted and ablated root canal dentine in the laser-treated groups. These findings were more obvious in root canals lased in association with black ink. All apical foramina in the lased group remained patent.


CONCLUSIONS
Nd:YAG laser irradiation with black ink increased the amount of melted and ablated dentine areas compared with that without black ink. Nd:YAG lasing in association with black ink did not result in a reduction of either coronal or apical microleakage in root filled teeth.
Depraet
F J H W
FJ
Department of Operative Dentistry and Endodontology, Dental School, Ghent University, Ghent University Hospital, Gent, Belgium.
De Bruyne
M A A
MA
De Moor
R J G
RJ
D000538:Aluminum Silicates; D001729:Bismuth / Q000737:chemistry; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification; D003786:Dental Pulp Cavity / Q000528:radiation effects / Q000648:ultrastructure*; D003804:Dentin / Q000528:radiation effects / Q000648:ultrastructure; D004338:Drug Combinations; D004853:Epoxy Resins / Q000737:chemistry*; D005456:Fluorescent Dyes; D006171:Gutta-Percha / Q000737:chemistry; D006801:Humans; D053685:Laser Therapy; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D011312:Pressure; D012235:Rhodamines; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012834:Silver / Q000737:chemistry; D016369:Smear Layer; D014025:Titanium / Q000737:chemistry; D015019:Yttrium
D000538:Aluminum Silicates; D004338:Drug Combinations; D004853:Epoxy Resins; D005456:Fluorescent Dyes; D012235:Rhodamines; D012387:Root Canal Filling Materials; D009354:Neodymium; D012834:Silver; C028044:epoxy resin AH-26; D015019:Yttrium; D006171:Gutta-Percha; D014025:Titanium; C029773:rhodamine B; D001729:Bismuth