We investigated the transmission of Nd: YAG laser through human dentin and reported the results on the Journal of Japanese Society for Laser Dentistry VOL.7, No 1.
In this report, we further investigated the transmission of GaAlAs semiconductor laser through human dentin. The materials and methods were in accordanse with the previous report, but GaAlAs semiconductor laser equipment used in this study was DSL-1000 (Morita). The irradiation conditions of GaAlAs semiconductor laser were normal pulse, 700 mW, 810 nm and 2-second duration.
Three measurements of the intensity of transmitted laser light (T-light) through dentin of approximately 1 mm thickness were performed by a power monitor (Ophir Optics Ltd). And the power monitor was transferred 2 mm perpendicularly from the center of laser light (C-L). And then the measurment of the intensity of scattered laser light (S-light) was trebled. And then the power monitor was further transferred 4, 6, 8, 10 and 12 mm from C-L and the measurment of the intensity of S-Light was trebled at each displacement from C-L.
Then the thickness of dentin (DTh) was stepwise decreased with the interval of approxi mate 100 μm, and T-light and S-light was repeatedly measured in the same manner described above.
Relationship between DTh and T-light or S-light, and the relationship between the distance from C-L and T-light or S-light were analyzed by regression analysis.
The following results were obtained;
1. T-light was found to decrease with increasing the thickness of dentin and an exponential relationship was found between DTh and T-light.
2. An exponential relationship between DTh and S-light was found when the distance between C-L was within 6 mm, but no significant relationship was found if the distance from C-L exceeded 8 mm.
3. S-light was found to decrease with increasing the distance between C-L and a linear relationship was found between the distance from C-L and S-light irrespective of DTh.
4. The extent of scattering of S-light through human dentin was greater on GaAlAs semiconductor laser than that on Nd: YAG laser.
(J. Jpn. Soc. Laser Dent. 8: 1-6, 1997 Reprint requests to Dr. ZENNYU)
