Antimicrobial effect and transdentinal diffusion of new intracanal formulations containing nitrofurantoin or doxycycline.

Ana Rita Silva,Elizabete Brasil Santos,Shelon Cristina Souza Pinto,Irene Pina Vaz,Manuel Fontes Carvalho,João Carlos Gomes

doi:10.1590/0103-6440201302338

Ana Rita Silva, Elizabete Brasil Santos + Show 4 more

Open Access

https://doi.org/10.1590/0103-6440201302338

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Abstract

The aim of this study was to investigate in vitro the antimicrobial effect and diffusion against E. faecalis of new intracanal medications on the external root surface. The medications tested were a placebo gel (PC); the new formulations with either 3% nitrofurantoin (NIT) or 3% doxycycline hydrochloride (DX) and 2% chlorhexidine (CHX) gel as positive control. The new formulations were tested using the traditional agar diffusion test (ADT) and an adapted agar diffusion method (AADM), where the teeth were filled with the medications and left to diffuse on agar surface seeded with E. faecalis. In the ADT, the larger zones of microbial growth inhibition were seen in DX, followed by CHX and NIT. In the AADM test only DX and CHX showed antimicrobial effect. Statistically significant differences between groups were observed by the Kruskal-Wallis test (2=47.126; p<0.001). The new intracanal formulations with DX and NIT have demonstrated antimicrobial effect against E. faecalis, but only DX was able to diffuse through the dentinal tubules and exert antimicrobial effect outside the roots.

Highlights

Endodontic infections are essentially polymicrobial and in most cases the microorganisms grow in the root canal system as sessile biofilms
Adapted Agar Diffusion Method (AADM) Figure 2 shows the area of microbial inhibition of the different intracanal medications through the external root surface against E. faecalis
In a multiple comparisons post-hoc procedure it was possible to observe statistically significant differences between CHX and doxycycline hydrochloride (DX) and the other groups. In both tests (ADT and agar diffusion method (AADM)) DX presented the largest zones of microbial growth inhibition, demonstrating a better antibacterial effect and/or a better diffusion ability compared with NIT and CHX

Summary

Introduction

Endodontic infections are essentially polymicrobial and in most cases the microorganisms grow in the root canal system as sessile biofilms. Despite the action of the chemomechanical preparation with antimicrobial irrigating solutions, some microorganisms, including E. faecalis, may survive in the root canal system. The intracanal medication should have a broad antimicrobial spectrum, should be able to diffuse through the dentinal tubules and all ramifications of the root canal system including the areas that neither the instruments nor the irrigating solution can reach, and should not be cytotoxic to live tissues [3]. Calcium hydroxide (Ca(OH)2) is believed to have most of the properties of an ideal root canal dressing due to its high pH. It is not effective against all species of microorganism found in the root canal system [4]

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