Disinfection effect of microwave radiation on Bacillus subtilis as indicator organism on contaminated dental stone casts under dry and wet conditions.

GMS hygiene and infection control · 2017 · Benefit · Low evidence

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BenefitLow evidencePaper 6608

In an in vitro experiment using 34 contaminated stone half-casts, both wet and dry groups achieved a high level of disinfection (~6-log reduction) after microwave irradiation. No statistically significant difference in disinfection level was reported between …

Study snapshot

PublicationGMS hygiene and infection control · 2017

Study typein_vitro

Reported directionBenefit

Evidence ratingLow

Abstract

The disinfection of dental stone casts using microwave radiation has been shown, but doubts remain regarding its efficacy under various conditions. The aim of the present study was to evaluate the efficacy of microwave disinfection on wet and dry dental stone casts contaminated by a resistant microorganism. In this in vitro study, 34 stone half-casts were prepared, contaminated with and divided into two groups. After drying the specimens of one group for 15 minutes using 450 W microwave energy, all the wet and dry specimens were exposed to 900 W microwave energy for 5 minutes. Specimens were then individually transferred to nutrient broth culture medium and after 10 minutes, one milliliter from each tube was cultured in nutrient agar media for 24 hours, and the colonies were counted in CFU/mL. Data were analyzed using multifactorial ANOVA and Bonferroni tests. Casts in both wet and dry groups were disinfected to a high level (6 log), with no statistically significant differences between them (P<0.05). According to the results, microwave irradiation can disinfect dental stone casts to a high degree, irrespective of moisture level. However, the result should be confirmed by exploring with other species of resistant microorganisms.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionbenefit

PopulationNot supplied

Sample size34

Exposuremicrowave · 450 W for 15 minutes (drying step for one group) and 900 W for 5 minutes (exposure for all specimens)

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Outcomes measured

Disinfection efficacy (colony counts, CFU/mL; log reduction) on contaminated dental stone casts under wet vs dry conditions

Limitations

In vitro study (not clinical/real-world use)
Only one indicator organism (Bacillus subtilis) was tested; authors note need to confirm with other resistant species
Microwave frequency not reported

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "microwave",
    "source": "microwave disinfection (dental stone casts)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "450 W for 15 minutes (drying step for one group) and 900 W for 5 minutes (exposure for all specimens)"
  },
  "population": null,
  "sample_size": 34,
  "outcomes": [
    "Disinfection efficacy (colony counts, CFU/mL; log reduction) on contaminated dental stone casts under wet vs dry conditions"
  ],
  "main_findings": "In an in vitro experiment using 34 contaminated stone half-casts, both wet and dry groups achieved a high level of disinfection (~6-log reduction) after microwave irradiation. No statistically significant difference in disinfection level was reported between wet and dry casts.",
  "effect_direction": "benefit",
  "limitations": [
    "In vitro study (not clinical/real-world use)",
    "Only one indicator organism (Bacillus subtilis) was tested; authors note need to confirm with other resistant species",
    "Microwave frequency not reported"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "microwave radiation",
    "disinfection",
    "dental stone casts",
    "Bacillus subtilis",
    "wet vs dry",
    "in vitro",
    "CFU/mL",
    "log reduction"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.3205/dgkh000294
PubMed: 28840089

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