Disinfection effectiveness of photodynamic therapy combined with EDTA on infected lateral canals in vitro / 国际生物医学工程杂志

ABSTRACT

Objective:To investigate the disinfection effectiveness of photodynamic therapy (PDT) combined with ethylenediaminetetraacetic acid (EDTA) disodium salt solution on enterococcus faecalis in lateral root canals.Methods:Sixty-four human single root canal premolars were selected to prepare artificial root canal collaterals, and E. faecalisin root canal collateral infection models were established. The infection model was divided into PDT group ( n=16), PDT combined with EDTA group ( n=16), positive control group ( n=16) and negative control group ( n=16) according to random number table method. In the PDT group, 40 μg/ml hematoporphyrin monomethyl ether was injected into the root canal, and then the root canal was irradiated with a 45 mW laser for 90 s after 5 min incubation. In the PDT combined with EDTA group, the root canal was given 5 ml EDTA solution with 17% mass fraction for 1 min, and then treated with the method same as the PDT group. In the positive control group, the root canal were given 5 ml NaClO solution with a mass fraction of 5.25 % for 1 min. In the negative control group, the root canal were given NaCl solution with a mass concentration of 9 g/L for 1 min. Before and after the treatments, samples were taken in the lateral branches of the root canal with a K file to count plate colonies. After treatments, the roots of each group were placed in sterile brain heart infusion broth (BHI) medium for anaerobic culture for 24 h, and then sampled with a K file, and the number of root canal collaterals was detected statistically. Scanning electron microscopy was used to observe the morphology of the inner wall of lateral branches of root canals after treatments. Results:The sterilization rate of PDT combined with EDTA group was 99.56%, which was significantly higher than that of negative control group (1.98%), positive control group (85.87%) and PDT group (87.53%), the differences were statistically significant (all P<0.05). The reply experiment shows that the number of infection root canals was only 5, which was less than the negative control group (15), positive control group (12) and PDT group (11), and the differences were statistically significant (all P<0.05). Scanning electron microscopy observations showed that no obvious E. faecalis adhered to the inner wall of root canal of PDT combined with EDTA group. Conclusions:PDT combined with EDTA has a good disinfection effectiveness on E. faecalis in lateral canals, and it is expected to provide a new method for the effective killing of E. faecalis in lateral canals in clinical root canal therapy.