Antibacterianos

Antibacterial effectiveness of peracetic acid and conventional endodontic irrigants
Juliane Maria Guerreiro-Tanomaru; Renata Dornelles Morgental; Norberto Batista Faria-Junior; Fábio Luis Camargo Vilela Berbert; Mário Tanomaru-filho
Department of Restorative Dentistry, Araraquara Dental School, UNESP - Univ. Estadual Paulista, Araraquara, SP, Brazil
ABSTRACT
This study evaluated the invitro antibacterial activity of conventional and experimental endodontic irrigants against Enterococcus faecalis. The following substances were evaluated by direct contact test: 2.5% sodium hypochlorite (NaOCl); 2% chlorhexidine (CHX); 1% peracetic acid. After different contact periods (30 s, 1, 3, and 10 min), a neutralizing agent was applied. Serial 10-fold dilutions were prepared and plated ontotryptic soy agar (TSA) and the number of colony-forming units per milliliter (CFU/mL) was determined. Sterile saline was used as a negative control. Both 2.5% NaOCl and 2% CHX eliminated E. faecalis after 30 s of contact. Peracetic acid reduced the bacterial counts by 86% after 3 min and completely eliminated E. faecalis after 10 min. These results allow us to conclude that 1% peracetic acid iseffective against E. faecalis, despite its slower action compared with 2.5% NaOCl and 2% CHX.
KeyWords: sodium hypochlorite, chlorhexidine, peracetic acid, root canal irrigants, Endodontics

RESUMO
Este estudo avaliou, in vitro, a atividade antibacteriana de soluções irrigadoras convencionais e experimentais sobre Enterecoccus faecalis. As seguintes substâncias foram avaliadas por teste de contatodireto: hipoclorito de sódio (NaOCl) a 2,5%, clorexidina (CHX) a 2%, ácido peracético a 1%. Após diferentes períodos de contato (30 s, 1, 3 e 10 min), um agente neutralizante foi empregado. Diluições decimais seriadas foram realizadas e semeadas em placas de tryptic soy agar (TSA). O número de unidades formadoras de colônia por mililitro (UFC/mL) foi determinado. Solução salina foi utilizada comocontrole negativo. Ambos, NaOCl a 2,5% e CHX a 2%, eliminaram E. faecalis após 30 s de contato. O ácido peracético reduziu a contagem bacteriana em 86% após 3 min e eliminou completamente E. faecalis após 10 min. Estes resultados permitem concluir que o ácido peracético a 1% é efetivo sobre E. faecalis, apesar de sua ação mais lenta quando comparado ao NaOCl a 2,5% e CHX a 2%.

 
 
INTRODUCTIONPulpal and periapical diseases are inflammatory conditions of microbial etiology (1). Therefore, one of the main goals of endodontic treatment is the elimination of infection in the root canal system in order to obtain an environment conducive to healing of apical periodontitis (2). Persistence of microorganisms after treatment is the main cause of failure in endodontic therapy (3). Enterococcusfaecalis is a Gram-positive bacterium capable of invading dentin tubules and binding to collagen. Moreover, this microorganism has shown resistance to several irrigating solutions and medications used in Endodontics (4).
Root canal preparation per se, comprising instrumentation and irrigation, is unable to fully eradicate endodontic infection (5) because in many cases bacteria can propagate toareas of difficult access, such as lateral canals, apical deltas and dentin tubules (6). New intracanal irrigants and medications have been evaluated in order to reach higher success rates in endodontic therapy.
Sodium hypochlorite (NaOCl) still is the most commonly used irrigant. It is recognized for its antimicrobial activity, tissue-dissolving and detergent actions, and capacity to neutralizetoxic products (7). A solution of 2.5% NaOCl is generally used when treating teeth with necrotic pulp and apical periodontitis (8). NaOCl solutions at higher concentrations have a greater irritating effect on the apical and periapical tissues (9).
Chlorhexidine gluconate (CHX) is a potent antiseptic, widely used for chemical control of dental plaque. The use of CHX as an endodontic irrigant has...