Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials

Abstract

This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.

Conducts of disinfection, pouring and storage of irreversible hydrocolloid impressions by undergraduate students

“…Irreversible hydrocolloids are routinely used in clinical dental practice; however, they require proper disinfection because their structure is similar to agar polysaccharides, which are known to be excellent substrates for microorganisms 2,3 . The hydrophilic nature of this impression material allows greater retention of bacteria (two to five times greater than that with elastomer molds) 3,4 .…”

“…This outcome Rev Odontol UNESP. 2016 Jan-Feb; 45(1): [1][2][3][4][5][6] Conducts of disinfection, pouring and storage... 3 attests for the progression of learning and the increased perception of the use of biosecurity measures in infection control.…”

“…This material is characterized as unstable when considering the need to disinfect it, because it has a structure similar to agar polysaccharides that are known as excellent substrates for microorganisms 2,3 , as well as its hydrophilic nature allows greater retention of bacteria, being checked two to five times larger when compared to elastomeric impression 3,4 . The possibility of contamination between the patient and the dental team by manipulating molds and models, makes it essential to carry out disinfection of the molds as cross-infection control measures [5][6][7] .…”

Contaminação microbiológica de fios retratores: um estudo in vitro

“…Regarding impression materials, particularly irreversible hydrocolloids, Casemiro et al [3] tested six types of irreversible hydrocolloids and found viable bacteria and fungi in all samples. Likewise, Oskoee et al [1] tested three commercial brands of irreversible hydrocolloids and found that 90% of the samples were contaminated.…”

“…Some materials have shown deficiencies, and microorganisms have been identified and isolated, for example, in the powder of impression material containers [3], as well as in instruments used in endodontics [4,5] and orthodontics [6,7].…”