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Optimal parameters for laser tissue soldering. Part I: Tensile strength and scanning electron microscopy analysis
Author(s) -
McNally Karen M.,
Sorg Brian S.,
Chan, Eric K.,
Welch Ashley J.,
Dawes Judith M.,
Owen Earl R.
Publication year - 1999
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/(sici)1096-9101(1999)24:5<319::aid-lsm2>3.0.co;2-n
Subject(s) - ultimate tensile strength , soldering , materials science , scanning electron microscope , bond strength , laser , composite material , optics , adhesive , physics , layer (electronics)
Background and Objectives The use of liquid and solid albumin protein solders to enhance laser tissue repairs has been shown to significantly improve postoperative results. The published results of laser‐solder tissue repair studies have, however, indicated inconsistent success rates. This can be attributed to variations in laser irradiance, exposure time, solder composition, chromophore type, and concentration. An in vitro study was performed using indocyanine green‐doped albumin protein solders in conjunction with an 808 nm diode laser to determine optimal laser and solder parameters for tissue repair in terms of tensile strength and stability during hydration. Study Design/Materials and Methods Twenty‐five different combinations of laser irradiance (6.4, 12.7, 19.1, 25.5, 31.8 W/cm 2 ) and exposure time (20, 30, 40, 50, 100 or 40, 60, 80, 100, 200 seconds) were used. The effect of changing bovine serum albumin (BSA) concentration (25% and 60%) and indocyanine green (ICG) dye concentration (2.5 mg/ml and 0.25 mg/ml) of the protein solder on the tensile strength of the resulting bonds was investigated. The effect of hydration on bond stability was also investigated using both tensile strength and scanning electron microscopy analysis. Results Tensile strength was observed to decrease significantly with increasing irradiance. An optimum exposure time was found to exist where further irradiation did not improve the tensile strength of the bond. Tensile strength was found to be greatly improved by increasing the BSA concentration. Finally, the lower ICG dye concentration increased the penetration depth of the laser light in the protein solder leading to higher tensile strengths. The strongest repairs were formed by using 6.4 W/cm 2 irradiation for 50 seconds with a protein solder composed of 60% BSA and 0.25mg/ml ICG. In addition, the solid protein solder provided more stable adhesion to the tissue than did the liquid protein solder when the tissue was submerged in a hydrated environment. Conclusions This study greatly enhances the current understanding of the various factors affecting the soldering process. It provides a strong basis for optimization of the laser light delivery parameters and the solder constituents to achieve strong and reliable laser tissue repairs. Lasers Surg. Med. 24:319–331, 1999. © 1999 Wiley‐Liss, Inc.