Antimicrobial Photodynamic Action on Dentin Using a Light-Emitting Diode Light Source

Abstract

Objective: The aim of this study was the evaluation of two different photosensitizers activated by red light emitted by light-emitting diodes (LEDs) in the decontamination of carious bovine dentin. Materials and Methods: Fifteen bovine incisors were used to obtain dentin samples which were immersed in brain-heart infusion culture medium supplemented with 1% glucose, 2% sucrose, and 1% young primary culture of Lactobacillus acidophilus 10 8 CFU/mL and Streptococcus mutans 10 8 CFU/mL for caries induction. Three different concentrations of the Photogem solution, a hematoporphyrin derivative (1, 2, and 3 mg/mL) and two different concentrations of toluidine blue O (TBO), a basic dye (0.025 and 0.1 mg/mL) were used. To activate the photosensitizers two different light exposure times were used: 60 sec and 120 sec, corresponding respectively to the doses of 24 J/cm 2 and 48 J/cm 2 . Results: After counting the numbers of CFU per milligram of carious dentin, we observed that the use of LED energy in association with Photogem or TBO was effective for bacterial reduction in carious dentin, and that the greatest effect on S. mutans and L. acidophilus was obtained with TBO at 0.1 mg/mL and a dose of 48 J/cm 2 . It was also observed that the overall toxicity of TBO was higher than that of Photogem, and that the phototoxicity of TBO was higher than that of Photogem. Conclusion: Based on our data we propose a mathematical model for the photodynamic effect when different photosensitizer concentrations and light doses are used.

Photodynamic Effects of Curcumin Against Cariogenic Pathogens

“…Similar results have been shown in previous studies using different photosensitizers on oral bacteria. [38][39][40][41] One of the main observations made during the first tests to photoinactivate bacteria with conventional photosensitizers was the relative sensitivity of gram-positive strains to photodynamic inactivation. 24 This sensitivity was confirmed in our study.…”

Hypericin- and mTHPC-mediated photodynamic therapy for the treatment of cariogenic bacteria

“…However, PDT data from previous studies in mutans streptococci are available for a few other photosensitizers, including toluidine blue O [11,12,14,17,18,20], methylene blue [16,19], erythrosine [15,16], hematoporphyrin derivative [16,20], native and lysine-conjugated chlorin e6 [21], aluminium disulphonated or cationic Zn(II) phthalocyanine [22,23], and Rose Bengal [13]. Our results as well as the vast majority of the above published data underlined the usefulness of PDT to destroy mutans streptococci, supporting the general observation that Gram-positive bacteria are susceptible to inactivation by photodynamic procedures [31].…”

“…These included tricyclic dyes [11][12][13][14][15][16][17][18][19][20] or tetrapyrroles belonging to the classes of porphyrines [16,20], chlorins [21], and phthalocyanines [22,23]. However, to the best of our knowledge, neither mesotetra(hydroxyphenyl)chlorin (mTHPC) nor hypericin (HYP) had been tested for treatment of S. mutans or S. sobrinus by PDT.…”

Photodynamic antimicrobial therapy of curcumin in biofilms and carious dentine

“…Results of several studies demonstrated an antibacterial effect of PDT on oral bacteria in biofilms [13,14] and in dentine carious lesions [9,[15][16][17][18]. However, none of those studies used curcumin as a PS to kill cariogenic bacteria.…”