Efficacy of an impression disinfectant solution after repeated use: An in vitro study

Simon Chukwu; Alan Munn; Jennifer C Wilson; Hadeel Ibrahim; Dean Gosling; Robert M Love; Mahmoud M Bakr

doi:10.1016/j.heliyon.2023.e23792

Efficacy of an impression disinfectant solution after repeated use: An in vitro study

Heliyon. 2023 Dec 15;10(1):e23792. doi: 10.1016/j.heliyon.2023.e23792. eCollection 2024 Jan 15.

Authors

Simon Chukwu¹, Alan Munn², Jennifer C Wilson³, Hadeel Ibrahim⁴, Dean Gosling⁵, Robert M Love⁶, Mahmoud M Bakr⁷

Affiliations

¹ Clinical Dental technologist, L & T Dental Laboratory Bridgend, Wales, UK.
² Senior Lecturer in Biochemistry, School of Pharmacy and Medical Sciences, Griffith University, Queensland, Australia.
³ Associate Professor, School of Pharmacy and Medical Sciences, Griffith University, Queensland, Australia.
⁴ Lecturer in Prosthodontics, University of Melbourne, Prosthodontist at the Royal Dental Hospital of Melbourne, Australia.
⁵ Advanced Scientist - Laboratory Operations Manager, Queensland Public Health and Scientific Services (QPHaSS), Queensland Health, Queensland, Australia.
⁶ Dean of Dentistry, School of Medicine and Dentistry, Griffith University, Queensland, Australia.
⁷ Director of Clinical Education, Senior lecturer in General Dental Practice, School of Medicine and Dentistry, Griffith University, Queensland, Australia.

Abstract

Statement of problem: There are very few studies using Benzalkonium Chloride (BAC) as an active disinfection agent for immersion techniques and there are no studies investigating the efficacy of repeated use of a disinfectant solution.

Purpose: This study evaluated an impression disinfectant by testing bacterial contamination of disinfectant batches used in a clinical setting after repeated use.

Materials and methods: Liquid samples were collected from impression disinfectant solutions used to disinfect dental impressions taken at a university dental clinic. The experimental samples (500 ml from 1 L of solution) were collected from teaching and professional clinics and the in-house commercial processing laboratory and stored at room temperature each day of clinic operation over five weeks. To determine to what extent the disinfectant efficacy of the active product decreased over time, the following tests were carried out: a. Inoculation b. Gram staining technique c. Matrix Assisted Laser Desorption/Ionization Mass spectrometry (MALDI- MS). Microbial growth was monitored and photographed. A culture revival was made from colonies grown on sheep blood agar, to isolate pure colonies incubated for 24 h at 37 °C. Each morphologically distinct type of colony was gram stained and MALDI spectrometry analysis was performed using the VITEK MS (BioMerieux Inc.).

Results: Evidence of growth of bacteria was detected in teaching clinics' samples, and no growth from the professional clinic or the commercial laboratory.

Conclusions: The study demonstrated that the impression disinfectant solution tested is effective against common oral bacteria, despite some rare species such as Bacillus circulans, Bacillus horneckiae, Bacillus altitudinis/pumilus and Bacillus cereus showing evidence of survival in solutions used for disinfection of impressions. However, in a high use teaching clinic environment its efficacy deteriorated. Though a second level disinfection protocol in the commercial laboratory-maintained impression disinfection.