A COMPARISON OF SURFACE-ROUGHNESS AND COMPOSITE ENAMEL BOND STRENGTH OF HUMAN ENAMEL FOLLOWING THE APPLICATION OF THE ND-YAG LASER AND ETCHING WITH PHOSPHORIC-ACID/
Mt. Ariyaratnam et al., A COMPARISON OF SURFACE-ROUGHNESS AND COMPOSITE ENAMEL BOND STRENGTH OF HUMAN ENAMEL FOLLOWING THE APPLICATION OF THE ND-YAG LASER AND ETCHING WITH PHOSPHORIC-ACID/, Dental materials, 13(1), 1997, pp. 51-55
Objectives. This study was conducted to evaluate enamel morphology aft
er laser etching and acid etching and to determine the shear bond stre
ngth of composite to acid-etched and laser-treated enamel. Methods. En
amel from freshly extracted permanent molar teeth was subjected to eit
her laser treatment with an Nd:YAG laser in different laser parameters
or was exposed to 37% phosphoric acid for 60 s (Gluma Gel, Bayer Dent
al). Surface profile analysis of the enamel was undertaken with a Pert
hometer (S8P, Feinpruif). The results were analyzed by SPSS/PC multipl
e range test and Student-Newman Keuls procedure. Specimens were examin
ed in a scanning electron microscope (SEM). Shear bond strengths of ac
id-etched and laser-etched enamel/composite (Brilliant Dentin, Coltene
AG and Pekalux, Bayer Denial) were also determined. These results wer
e compared by SPSS/PC multiple range test. Results. The acid-etched sp
ecimens exhibited a qualitatively different type of enamel surface mor
phology when compared with the laser-treated specimens. Laser treatmen
t at higher exposures resulted in the formation of microcracks and fis
sures. No significant difference in surface roughness was observed bet
ween laser-treated enamel in three different parameters (10 pps, 0.8 W
; 15 pps, 1.0 W; 20 pps, 1.25 W) and acid-etched specimens. However, t
he mean bond strengths of all laser-treated specimens, regardless of t
he test parameters, were significantly lower (p < 0.05) than the acid-
etched enamel specimens. Significance. Although the laser roughened th
e surface of the enamel, it did not provide a surface as retentive as
a surface treated with conventional acid etching. It is concluded from
this study that the Nd:YAG laser operated under the conditions descri
bed cannot be recommended as a viable alternative to acid etching.