Introduction of 5-aminolevulinic acid as a theranostics agent in dentistry

Objective: The aim of this paper is to study the theranostic potential of 5-Aminolevulinic Acid (5-ALA)in dentistry. Methods: Photodynamic inactivation (PDI) and fluorescence spectroscopy of Streptococcus sanguis, and laser induced fluorescence (LIF) of several decayed teeth were performed using 5-ALA. Results: In the absence of 5-ALA, 15 min illumination of the bacteria by the means of an LED light source led to only 1.16% viability reduction. On the other hand, 5-ALA revealed remarkable dark toxicity at concentrations above 20 mu M. Furthermore, the synergistic effects of 10 mu M 5-ALA and illumination by the light source for 5 and 15 min intervals led respectivelyto0.74log10 and 1.69log10 reduction of viability. Also, fluorescence spectroscopy of the bacteria showed a direct relationship between emission line intensity at 620 nm and the concentration of 5-ALA. In dental experiments, following exposing tooth with 40 mM 5-ALA, a significant auto-fluorescence growth was observed just in the decayed parts. Conclusion: Based on the strong dual modality of 5-ALA to annihilate cariogenic bacteria through photodynamic inactivation and enhancing LIF intensity for identification of dental caries, 5-ALA is proposed as a theranostic agent in dentistry.