Objective: The purpose of this in vitro scanning electron microscopy (
SEM) study was to evaluate the effect of low fluence (energy density o
f 11.5 J/cm(2) and 100 J/cm(2)) argon laser irradiation on the surface
morphology of sound root surfaces. Summary Background Data: Previous
laboratory investigations have shown that argon laser irradiation of r
oot surfaces provided a protective effect against in vitro cariogenic
challenges. Methods: Root surfaces of extracted human molars were sect
ioned into treatment quarters: 1) mesiobuccal-no treatment control; 2)
mesiolingual-low fluence argon laser irradiation (0.231 Watts, 11.5 J
/cm(2) for 10 seconds); 3) distobuccal-no treatment control; and 4) di
stolingual-higher fluence argon laser irradiation (2.0 Watts, 100 J/cm
(2) for 10 seconds). All surfaces were critical-point dried, coated wi
th platinum and paladium under vacuum, and evaluated qualitatively for
intactness, surface morphology, surface deposits, and porosities in a
blinded fashion by scanning electron microscope. Results: The argon l
ased root surfaces demonstrated alterations of root surfaces with crea
tion of surface globular particulate material, microporosities, and de
pressions. Both low- and high-fluence lased root surfaces showed areas
with plaque-like plates with fine punctuate oval particulate material
on their surfaces. Conclusions: Argon laser irradiated root surfaces
produce surface granular to globular deposits that may provide readily
mobilized tooth mineral, which may become redeposited into the underl
ying root surface during a cariogenic challenge and enhance resistance
to caries formation. In addition, microporosities created by the argo
n laser may provide a means for bonding fluoride-releasing restorative
and preventive materials to root surfaces and further improve the roo
t surfaces' ability to resist cariogenic challenges.