In vitro effect of intracanal medicaments on strict anaerobes by means of the broth dilution method

Abstract

The determination of bacterial susceptibility to intracanal medicaments is a necessity. Nevertheless, few studies utilize the proper methodology to carry out that evaluation with anaerobes. In this study, the steps of a broth dilution method, carried out in microplates (microdilution) and tubes (macrodilution), to test the effect of traditional intracanal medicaments on anaerobic bacteria are described. The results are presented as values of minimal inhibitory and bactericidal concentrations (MIC and MBC). Standardized inocula of the anaerobic bacteria Prevotella nigrescens (ATCC 33563), Fusobacterium nucleatum (ATCC 25586) and Clostridium perfringens (ATCC 13124), in reinforced Clostridium medium (RCM) and supplemented Brucella broth, were submitted to different concentrations of calcium hydroxide, chlorhexidine digluconate, camphorated paramonochlorophenol and formocresol solutions. The drugs were diluted in the same culture broths, in microplates and tubes, and were then incubated in anaerobiosis jars at 37ºC for 48 or 96 hours. The determination of MICs was carried out through visual and spectrophotometric readings, and the determination of MBCs, through the plating of aliquots on RCM-blood agar. For that kind of study, the macromethod with spectrophotometric reading should be the natural choice. MICs and MBCs obtained with the macromethod were compatible with the known clinical performance of the studied medications, and the values varied according to the bacteria and culture media employed. RCM was the most effective medium and C. perfringens, the most resistant microorganism.

Antimicrobial activities of six essential oils commonly used as condiments in Brazil against Clostridium perfringens

“…Working inoculums were prepared by transferring 200 μL aliquots of this suspension to three test tubes and adjusting the volumes to 10 mL with reinforced clostridial medium (RCM; Oxoid) to give final concentrations of 2.0 × 10 5 CFU mL –1 . 12 …”

Antimicrobial effect of calcium hydroxide as an intracanal medicament in root canal treatment: a literature review - Part I.In vitrostudies

“…Ohara et al evaluated the antibacterial effect of several irrigants and found that Ca(OH) 2 was totally ineffective as saline 39. Studies that compared the effect of various agents showed that Ca(OH) 2 had only a weak effect 40,41,42,43. More recent studies that compared Ca(OH) 2 with other agents reported that Ca(OH) 2 was less effective than others 44,45,46.…”

In vitro-activity of oily calcium hydroxide suspension on microorganisms as well as on human alveolar osteoblasts and periodontal ligament fibroblasts

“…It was observed that although oleum pedum did not have any antibacterial property, the use of calcium hydroxide in high concentrations such as those present in OCHS acted as growth-inhibitory. Calcium hydroxide is used widely in endodontic treatment and in vitro evidence demonstrates it suppresses the growth of Candida albicans [28] and certain other anaerobically growing bacteria [29] although limited antimicrobial efficacy has translated in vivo following the analysis of root canals post-treatment [30,31]. In our in vitro assays, in contrast to calcium hydroxide, OCHS did not have any antibacterial effect which may suggest a counteracting effect of the other components of OCHS to calcium hydroxide.…”