Study on Laser Transmission through Tooth Structures by 40mW Ga-Al-As Semiconductor Laser

Abstract

  The purpose of this study was to measure the transmission rate of Ga-Al-As semiconductor laser through enamel and dentine.

  Nine extracted human parmanent teeth (3 anterior teeth, 3 premolar teeth and 3 molar teeth) were used. 40mW Ga-Al-As semiconductor laser was irradiated on the cervical surface of buccal half of the crown. The transmitted laser was measured with a phtodiode put on the pulpal side. Then, the thickness of the crown was reduced successively by grinding the teeth from the pulpal side and the relationship betweeen the transmission rate and tooth thickness was investigated.

  As a result, laser transmission showed an exponential increase according to the reduction of tooth thickness. The mean percent of laser transmission was 38.10% in 0.50mm, 28.04% in 0.75mm, 21.79% in 1.00mm, 16.38% in 1.25mm, 13.40% in 1.50mm, 9.82% in 1.75mm, 6.76% in 2.00mm, 4.95% in 2.25mm, 4.17% in 2.50mm, 4.42% in 2.75mm, 3.91% in 3.00mm, 3.01% in 3.25mm, 2.92% in 3.50mm thickness.