Removal of bacterial endotoxin from root surface with Er:YAG laser

Abstract

Purpose: To determine the potential of 2.94 microm Er:YAG laser radiation to remove bacterial endotoxin from root surfaces.

Materials and methods: 40 extracted teeth were divided into four groups of 10 samples each. A 16 mm2 area of the root surface on each sample was inoculated with an aliquot of 7 microl of a lipopolysaccharide suspension at a concentration of 50 IU/ml. LPS was derived from a non-oral Escherichia coli strain (E. coli 055:B5). Source of laser radiation was an Er:YAG laser emitting pulsed infrared radiation at a wavelength of 2.94 microm, with a pulse duration of 250 micros, and a pulse repetition rate of 15 pps. Three specimen groups were irradiated with 105 laser pulses at a radiation energy of 60 mJ, 100 mJ and 140 mJ. One specimen group was untreated (control). The LPS concentration with each sample was determined using a chromogenic, quantitative Limulus-amoebocyte-lysate assay. Statistical analysis was ANOVA and Scheffé-test.

Results: Mean LPS yield from the untreated control samples was 50.1 (+/- 35.9) IU/ml. Following laser irradiation the average LPS on the root surfaces was 19.86 (+/- 14.4) IU/ml at 60 mJ, 12.86 (+/- 8.1) IU/ml at 100 mJ and 8.58 (+/- 4.9) IU/ml at 140 mJ.