Date of Award

Spring 1990

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Miserendino, Leo

Second Advisor

Kos, William

Third Advisor

Walia, Harmeet


The objective of this project was to evaluate the potential of fiber optic directed Nd:YAG laser light to disinfect root canals that had been contaminated with spores. Fifty canals of extracted single rooted teeth were prepared to a size 50 master apical file, sterilized in ethylene oxide, and inoculated with a known quantity of B. stearothermophilus spores. Five experimental groups were treated as follows. Group I: Control, received no treatment. Group II: 3.0 min. exposure to 0.5% NaOCl. Group III: 1.0 min. exposure to laser light. Group IV: 3.0 min. exposure to 0.5% NaOCl plus 1.0 min. exposure to laser light. Group V: 3.0 min. exposure to 0.5% NaOCl plus 2.0 min. exposure to laser light. The laser was set to operate at a power output of 3 watts and 20 light pulses per second were delivered through a 320 μm quartz optical fiber. Teeth were flushed with 2.0 ml of sterile distilled water, and serial dilutions were incubated on blood agar to determine the number of colony forming units (CFU). A 22% recovery rate was observed in the control group. Reduction of CFU by NaOCl (Group II) was 88%. Laser treatment reduced CFU by 98% (Groups III and IV) and 99% (Group V). Statistical analysis revealed no significant differences between Groups II, III, IV and V. Group I was significantly different form the other treatment groups.



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