Bjf. Wong et al., HOLMIUM-YAG LASER-ABLATION CHARACTERISTICS IN CALVARIAL LAMELLAR AND CORTICAL BONE - THE ROLE OF WATER AND TISSUE MICROARCHITECTURE, Lasers in medical science, 10(3), 1995, pp. 181-188
The effect of tissue micro-architecture and water content on ablation
rates in bone is examined. Precisely machined and prepared porcine cal
varial lamellar and cortical bone were ablated with a Holmium-YAG lase
r (lambda=2.1 mu m). Lamellar and cortical bone differ substantially i
n their tissue micro-architecture. Both are porous hard tissues, which
differ predominantly in size and distribution of pores within the bon
e matrix. These hard tissues were ablated under physiological (wet) an
d chemically dehydrated conditions. The ablation rates over the range
of energy densities examined assumes many linear characteristics. Abla
tion rate (as a function of fluence) is considerably higher for dehydr
ated cortical bone (4.7 mu m cm(2) J(-1)) compared to fresh cortical b
one (1.49 mu m cm(2) J(-1)). This trend is also observed in lamellar b
one (2.31 mu m cm(2) J(-1) for wet and 0.37 mu m cm(2) J(-1) for dry).
Under both physiological and dehydrated conditions, cortical bone was
ablated faster. Mechanisms accounting for these observations are disc
ussed.