Quantifying light energy from 450 nm, 650 nm, 810 nm, and 980 nm wavelength lasers delivered through dental hard tissue

Abstract

Purpose: The energy available to treat the dental pulp after transmittance through overlying structures is clinically important for determining photobiological effects. This ex vivo study aimed to quantify laser energy delivery though the dental crown to the pulp from an initial energy of 5 J using four common laser wavelengths (λ = 450, 650, 810, and 980 nm). Material and methods: A total of 30 extracted healthy human teeth (anterior n = 10; premolar n = 10; molar n = 10) were longitudinally sectioned (Project Number: 2021/421, University of Sydney, NSW, Australia). Each sample was methodically exposed in random order to the four wavelengths. Each wavelength was operated at the same power (0.50 W) for 10 s to deliver 5.0 J with a total energy delivery of 10 J/cm2. Laser light was delivered with an 8-mm-diameter fiber bundle probe directed perpendicularly to the buccal cervical-third of the crown. The transmitted energy was measured twice and averaged using a periodically pre-calibrated power meter in blinded conditions. Data were analyzed using a general linear model with logarithmic transformation. Results: Wavelength and tooth thickness were significant predictors of optical transmittance (P < 0.05) while tooth type was significant only for the 450 nm wavelength. The average attenuation coefficients (µ) were 2.55, 2.45, 1.87, and 5.42 cm−1 (± 10%) for the 980, 810, 650, and 450 nm groups, respectively. Conclusion: Clinicians should recognize that significant attenuation occurs during laser energy delivery to the pulp, influenced by the wavelength, thickness, and tooth type. Our findings support the potential for laser energy delivery to the pulp for photobiomodulation applications.