The Photo-Activated Antibacterial Action of Toluidine Blue O in a Collagen Matrix and in Carious Dentine

Abstract

The main aim of this study was to determine the susceptibility to photo-activated disinfection (PAD) of Streptococcus mutans when the organism was present in a collagen matrix – an environment similar to that which would exist within a carious tooth. In addition, the susceptibility to PAD of bacteria present in carious human teeth was also determined. Light was delivered to the collagen and teeth using a system comprising a 0.8-mm diameter isotropic tip emitting light at 633 ± 2 nm. A single concentration of TBO (10 µg/ml) was used with both collagen and dentine. Two contact times, 30 and 180 s, were evaluated in intact collagen and additionally, for 180 s only, in collagen partially disrupted by shredding. The effect of energy doses from 1.8 to 14.4 J on the kills attained was assessed by determining the number of surviving viable bacteria. In carious dentine, two contact times, 30 and 60 s and one energy dose, 4.8 J, were used. Antibacterial effects were less than those obtained using planktonic suspensions with a maximum mean log reduction of 1.4 in shredded collagen and dentine. Increasing contact time increased the antibacterial effectiveness in both substrates although this was not always of statistical significance. Shredding the collagen resulted in significantly increased bacterial kills compared to those obtained in intact collagen for the 30-second contact time. The collagen matrix appeared to be a suitable model for carious dentine with advantages of availability and reproducibility. The results of this study have shown that PAD can achieve appreciable kills of oral bacteria, including S. mutans, when the organisms are embedded in a collagen gel or are present in carious teeth.

Photodynamic Effects of Curcumin Against Cariogenic Pathogens

“…Our findings corroborate those of other studies aimed at reducing microbial activity by using PDT. 27,29,31,32,52 As the primary odontopathogen present in the supragingival plaque, S. mutans is closely related to enamel caries. Lactobacilli generally colonize after S. mutans have exposed the dentino-enamel interface, and they are often cultured from established carious lesions.…”

An alternative regimen for root canal disinfection

“…Addition of TC followed by irradiation with light has been shown to kill high numbers of bacteria in planktonic suspension, in collagen and carious dentine, 24,25 and in root canals in vitro, 26 probably by disruption of the cell membrane by short range free radicals or reactive oxygen species. 27 The object of the current study was to evaluate the effect of using the novel disinfection system earlier in the treatment procedure and to compare this with the bacterial load after conventional endodontic preparation of the canals using hypochlorite by measuring the bacterial load at these points in the procedure.…”

The Antibacterial Potentiality of Photo-activated Disinfection Versus a Chemical Disinfection Solution on Carious Dentin

“…This may be attributed to that when the power of laser was increased, the disinfection effect increased (8) , where the subgroups with 50 mW output power (P2T1,P2T2) had slightly inferior results regarding elimination of microorganisms compared to the subgroups activated by 100 mW output power (P1T1,P1T2).…”

“…Accordingly, each tooth served as its own control. Each specimen weight ranged from 6-10 mg to standardize all specimens (8) .…”

“…In carious dentin, two contact times, 30 and 60 s and energy 4.8 j were used. The result showed that PAD can achieve appreciable kills of oral bacteria, including S. mutans, when the organism are embedded in a collagen gel or are present in carious teeth (8) .…”