Avaliação in vitro do potencial de descontaminação de canais radiculares infectados com enterococcus faecalis e da capacidade de dissolução tecidual através do uso da terapia fotodinâmica e do hipoclorito de sódio

Abstract

ARTIGO 1 : Introduction: Photodynamic therapy has been proposed to improve to root canal desinfection, but its role on certain bacterial species needs to be further ellucidated. Objective: to compare, in vitro, the action of photodynamic therapy and sodium hypochlorite in root canals infected with Enterococcus faecalis. Methods: The root canals of 45 single-rooted human extracted teeth were enlarged up to a file 60, autoclaved, inoculated with a suspension of Enterococcus faecalis and incubated for 60 days, with renewal of the culture medium every 48 hours. After that, samples were divided into five groups according to the protocol of decontamination: G1 (n = 5) positive control - no procedure; G2 (n = 10) negative control - distilled water; G3 (n = 10) - PAD, G4 (n = 10) NaOCl 2.5%; G5 (n = 10) - NaOCl 2.5% + PAD. Subsequently, samples were fixed on 25% glutaraldehyde, dehydrated, dried, metalized and subjected to scanning electron microscopy (SEM). The assessment was made of images taken at every root third at 5.000x magnification for the canal wall and 10.000x for the exposed tubule area, both in backscattering (BS), noting the effect of proposed treatments to the different thirds of the root canal. The presence of bacteria in the images was scored by position ranks from 1 to 45, where the higher the value, the cleanliness of the sample. Data were subjected to One-way ANOVA followed by post-hoc Tukey test (α = 0.05). Results: Group 5 had the highest mean position ranks for all thirds of the root canal, both in canal wall and in the exposed tubule area. Thus, it was the most effective in eliminating Enterococcus faecalis. Conclusion: the association NaOCl 2,5% + PAD is an efficient protocol for the elimination of Enterococcus faecalis present in the dentinal surface and deep into the dentinal tubules.

ARTIGO 2 : Purpose: Evaluate the bovine pulp tissue dissolution ability of photodynamic therapy. Methods: Twenty pieces of bovine pulp tissue were weighed and divided randomly into four groups (n = 5), according to the cleaning protocol: G1 - distilled water (negative control), G2 - sodium hypochlorite 1% (positive control), G3 - photodynamic therapy, G4 - sodium hypochlorite 1% + photodynamic therapy. The observation of the events of dissolution was performed by two observers blinded in relation to the test using 2x loupe magnification, recording time in minutes until complete tissue dissolution. The total observation time was 2 hours. The dissolution rate was calculated dividing the weight of the fragment pulp (mg) by the time of dissolution (mg / min). Results: only group 2 (NaOCl) was able to promote complete dissolution of pulp tissue. In the other groups there was no occurrence of complete dissolution of the samples. The mean dissolution time for samples from group 2 (NaOCl) was 1.26 mg / min. Conclusion: photodynamic therapy was not able to dissolve the fragments of bovine pulp tissue and was not able to accelerate the rate of dissolution.