Thermodynamic basis for comparative photobiomodulation dosing with multiple wavelengths to direct odontoblast differentiation.

Multiple wavelength devices are now available for photobiomodulation (PBM) treatments, but their dosimetry for individual or combinatorial use remains unclear. The present work investigated the effects of 447, 532, 658, 810, 980 and 1064 nm wavelengths on odontoblast differentiation at 10 mW/cm 2 using either equal treatment time for conventional fluence (300 seconds for 3 J/cm 2 ) or varying times to adjust for individual wavelength photon fluence (4.6 p.J/cm 2 ). Both 447 and 810 nm significantly increased alkaline phosphatase (ALP) activity, while 1064 nm showed reduced ALP activity at 3 J/cm 2 . However, ALP induction was significantly improved when equivalent photon fluence dosing was used. Other wavelengths did not show significant changes compared to untreated controls. The data suggest that accounting for wavelength-specific photon energy transfer during PBM dosing could improve clinical safety and efficacy.