Effect of chitosan nanoparticles and the temperature and pH variations of sodium hypochlorite on biofilms formed in situ

Author(s)

Aldo Enrique del Carpio Perochena

• Document type: Doctoral Thesis
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2015-02-24

Examining board members

Clovis Monteiro Bramante; Flaviana Bombarda de Andrade; Ricardo Affonso Bernardes; Izabel Regina Fischer Rubira de Bullen; Giulio Gavini

• Advisor: Clovis Monteiro Bramante

Abstract

The aim of this study was to evaluate if the variation of the sodium hypochlorite (NaOCl) temperature and pH increase its antibacterial and dissolution abilities. It was also evaluated if the chitosan nanoparticles (CNPs) inhibit the bacterial growth and remove smear layer. Two hundred-sixty bovine dentin blocks were infected intraorally. The experimental solutions were 1% and 2.5% NaOCl at room temperature and 37oC. the solution was acidified at pH 5 and 7. The exposure times were 5 and 20 min. The specimens were analyzed pre- (control) and postirrigation. After that, the samples were incubated in BHI and analyzed again to evaluate the bacterial recolonization. These procedures were performed in duplicate to access the percentage of dentinal cleaning. The samples were rinsed with a final irrigation of CNPs and analyzed immediately to determine the chelating effect, or infected intraorally to evaluate its antibacterial ability. NaOCl showed antibacterial power and was able to significantly dissolve the biofilm regardless its temperature. NaOCl at acid pHs showed great antibacterial properties, however its dissolution ability decreased. The CNPs were able to remove significantly the smear layer and interfere with the bacterial growth on dentin. Therefore, the NaOCl temperature is not relevant when the solution was tested on multi-specie biofilms. The antibacterial power of NaOCl was inversely proportional to its pH, while its dissolution capacity was directly proportional. CNPs could be an alternative instead of EDTA due to its chelating properties and ability to interfere with the earlier bacterial adhesion on dentin. (AU)

• FAPESP's process: 11/08184-8 - EFFECT OF CHITOSAN NANOPARTICLES AND THE SODIUM HYPOCHLORITE IN DIFFERENT CONCENTRATION, TEMPERATURE AND PH ON ORAL BIOFILMS FORMED IN SITU
• Grantee: Aldo Enrique Del Carpio Perochena
• Support Opportunities: Scholarships in Brazil - Doctorate