Aldo del Carpio-Perochena
1*, Clovis Monteiro Bramante
2, Marco Hungaro Duarte
2, Flaviana Bombarda de Andrade
2, Marcia Zardin Graeff
3, Marina Marciano da Silva
1, Bruno Cavalini Cavenago
1, Samuel Lucas Fernandes
41 Doctor of Sciences, Department of Endodontics, Bauru Dental School of Bauru, University of São Paulo, Bauru, São Paulo, Brazil
2 Associate Professor, Department of Endodontics, Bauru Dental School of Bauru, University of São Paulo, Bauru, São Paulo, Brazil
3 Laboratory Specialist, Integrated Research Centre (CIP), Bauru Dental School of Bauru, University of São Paulo, Bauru, São Paulo, Brazil
4 Master of Sciences, Department of Endodontics, Bauru Dental School of Bauru, University of São Paulo, Bauru, São Paulo, Brazil
Abstract
Background and aims.
Increasing
the temperature of sodium hypochlorite (NaOCl) enhances its dissolution and
antibacterial properties. However, the high resistance of multi-species
biofilms could restrict the effect of the solution regardless of its temperature,
enabling the long-term recovery of the surviving bacteria. The aim of this
study was to investigate if the increase of temperature of NaOCl improves its
antibacterial and dissolution ability on oral biofilms and if the
post-treatment remaining bacteria were capable of growing in a nutrient-rich
medium.
Materials and methods. Forty dentin blocks were infected intra-orally for 48 hours. Then, the
specimens were treated with 1% and 2.5% NaOCl at room temperature (22ºC) and
body temperature (37ºC) for 5 and 20 min. The percentage of live cells
and the biovolume were measured pre- (control) and post-treatment and after
the biofilm revitalization. Four confocal ‘stacks’ were chosen from random
areas of each sample. Statistical analysis was performed using Kruskal-Wallis
and Dunn tests. Statistical significance was defined at P <0.05.
Results.
All
the NaOCl groups were effective in dissolving the biofilm at any temperature,
concentration and contact time without statistical differences among them (P >0.05). The 1%-NaOCl for 5min
was not able to significantly kill the bacteria, regardless of its
temperature and contact time (P
>0.05).
Conclusion.
The
temperature variation of the NaOCl was not relevant in killing or dissolving
bacterial biofilms. Twenty-four hours of reactivation did not appear to be
enough time to induce a significant bacterial growth.