Sodium Hypochlorite

Effective methods for decontamination of Shiga toxin-producing Escherichia coli (STEC) on beef were evaluated by 48 mL spraying, 100 mL, and 500 mL flushing with ethanol, hydrogen peroxide, peracetic acid, acidified sodium chlorite, and sodium hypochlorite in this study. The flushing with 500 mL of 1,000 ppm peracetic acid was most effective, reducing pathogens by 2.8 log CFU/cm², followed by 1,200 ppm acidified sodium chlorite. The spraying with 1,000 ppm peracetic acid reduced pathogens by 1.6 log CFU/cm². The flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite, and 50, 100, 200, and 500 ppm peracetic acid significantly reduced the STEC population compared with those treated with distilled water (p < 0.05), reducing pathogens by 2.1, 2.4, 1.6, 1.8, 2.1 and 2.4 log CFU/cm², respectively. Additionally, the flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite significantly changed the color of beef samples (p < 0.05), whereas 100-500 ppm peracetic acid did not significantly change the color (p > 0.05). The flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite and 200 and 500 ppm peracetic acid significantly changed the odor of beef samples compared with those treated with distilled water (p < 0.05). There was no difference in the reduction of STEC population between peracetic acid treatment at 25 °C and 55 °C, with or without washing with sterilized distilled water after decontamination. Washing with distilled water after flushing with peracetic acid tended to reduce the odor of the samples. These results suggest that treatment with 100, 200, and 500 ppm peracetic acid, followed by washing with distilled water, might reduce the STEC population without retaining the odor of the sanitizer.

Dentinal microcracks have been supposedly associated with unrestorable vertical root fractures and consequently long-term treatment failure. This study aimed to investigate whether in vivo root canal instrumentation in mandibular incisors with vital pulps causes dentinal microcracks using two different irrigating solutions.

Five patients with four vital mandibular incisors indicated for extraction were included. In vivo root canal preparation was performed using Reciproc R40 (tip #40 and taper 0.06). From these, two teeth were randomly assigned for root canal instrumentation irrigated with 5.25 % sodium hypochlorite irrigation (n = 10) or 2 % chlorhexidine gel with saline solution irrigation (n = 10). In sequence, all teeth were carefully extracted, stored in saline solution until microtomography (µCT) scan. Images were reconstructed and assessed for the presence or absence of dentinal microcracks where microcracks originating from the root canal lumen would be considered. All reconstructed samples were analysed dynamically and rendered in videos through the entire extension of the teeth, evaluating the axial cuts considering each third separately from the apex to the enamel-dentinal junction. Teeth were analysed using the DataViewer software at 100 % magnification without filters by three examiners blinded to the condition allocation.

No complete dentinal microcracks were observed after root canal instrumentation of mandibular incisors with vital pulps using Reciproc R40 regardless the irrigating solutions, 5.25 % sodium hypochlorite or 2 % chlorhexidine gel.

In vivo root canal instrumentation of mandibular incisors with vital pulps and bone/periodontal insertion does not cause dentinal microcracks and the irrigating solutions tested did not influence this occurrence. Microcrack evaluation must be performed in vivo conditions of dental tissue moist and periodontal support to avoid dryness dentinal alterations after extraction provoking false positive results.

Reciprocating instrumentation performed in vivo is safe and do not induce dentinal microcracks in mandibular incisors.