Argon Laser Irradiation Effects on Sound Root Surfaces: In Vitro Scanning Electron Microscopic Observations

Abstract

Objective: The purpose of this in vitro scanning electron microscopy (SEM) study was to evaluate the effect of low fluence (energy density of 11.5 J/cm² and 100 J/cm²) argon laser irradiation on the surface morphology of sound root surfaces. Summary Background Data: Previous laboratory investigations have shown that argon laser irradiation of root surfaces provided a protective effect against in vitro cariogenic challenges. Methods: Root surfaces of extracted human molars were sectioned into treatment quarters: 1) mesiobuccal—no treatment control; 2) mesiolingual—low fluence argon laser irradiation (0.231 Watts, 11.5 J/cm² for 10 seconds); 3) distobuccal—no treatment control; and 4) distolingual—higher fluence argon laser irradiation (2.0 Watts, 100 J/cm² for 10 seconds). All surfaces were critical-point dried, coated with 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 lased root surfaces demonstrated alterations of root surfaces with creation of surface globular particulate material, microporosities, and depressions. 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 underlying root surface during a cariogenic challenge and enhance resistance to caries formation. In addition, microporosities created by the argon laser may provide a means for bonding fluoride-releasing restorative and preventive materials to root surfaces and further improve the root surfaces' ability to resist cariogenic challenges.