Quantitative Analysis of Selected Microorganisms Present at Various Sites in a Prosthetics Clinic and Dental Laboratory during Complete Denture Fabrication

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

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 impression disinfectanat 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.

Antimicrobial effect and the mechanical and surface properties of a self-disinfecting and a chlorhexidine-incorporated Type IV dental stone

STATEMENT OF PROBLEM

Stone casts are subject to contamination, but whether disinfectants incorporated into the stone are effective is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the antimicrobial activity and the mechanical and surface properties of self-disinfecting gypsum (SDG) and gypsum mixed with 2% chlorhexidine (GCHX).

MATERIAL AND METHODS

Antimicrobial action was evaluated using the diffusion-disk technique on Streptococcus aureus and Candida albicans 1 hour and 24 hours after pouring the gypsum. The groups were SDG, GCHX, a positive control (PC) of gypsum mixed with distilled water, and a negative control (NC) of filter paper disk soaked with 2% chlorhexidine; n=8. Inhibition halos were measured using the ImageJ software program and statistically analyzed using the repeated measures mixed ANOVA with time×group interaction. Compressive strength (CS) in MPa and surface roughness (SR) in μm (parameters: Ra - roughness average; and Sa - 3-dimensional (3D) arithmetic mean of the surface profile) tests were performed to characterize the specimens (evaluated groups: SDG, GCHX, and PC; n=10). CS data were analyzed by a 2-way ANOVA with time×group interaction, and SR data by a 1-way ANOVA (α=.05).

RESULTS

For S aureus, there were differences between GCHX and SDG at 1 hour and 24 hours (P<.05), but no significant differences were found for C albicans (P>.05). GCHX was better than PC, except for C albicans, and showed a reduction in CS when compared with PC and SDG (P<.05) at all time intervals. The SR of GCHX increased (Ra:1.76, Sa:2.08) when compared with PC (Ra:0.89, Sa:1.12) and SDG (Ra:1.03, Sa:1.35) (Ra: P<.004 and Sa: P<.001).

CONCLUSIONS

The antimicrobial activity of GCHX against S aureus was better than that of SDG, but neither had an effect against C albicans. As for CS and SR, GCHX presented a decrease in properties when compared with PC and SDG but was within the American Dental Association #25 specification values.

Infection control in dentistry during COVID - 19 pandemic: what has changed?

The novel coronavirus (COVID-19) pandemic has emerged disrupting many socio-economical and healthcare aspects across the world. This virus can be transmitted by symptomatic and asymptomatic individuals through saliva and contact. Due to its airborne transmission, aerosols created by natural activities and during dental treatment of infected individuals have become a potential vehicle of transmission and threat. The objective of this review was to assess the existing infection control measures taken in dental health-care settings and suggest modifications to reduce the transmission of novel coronavirus. This is a general review publication. Literature search was made at National Library of Medicine, Pubmed using key words such as "dentistry and COVID", "dentistry and COVID and infection control". Publications related to behaviour, education, ethics, treatment and childcare were excluded. Publications describing general aspects of infection control were reviewed. Keyword "Dentistry and COVID and Infection control" generated 70 publications which were reviewed. Infection control measures in dentistry are designed to minimise cross transmission mainly of blood borne pathogens. The unique nature of COVID-19 including highly infectious and transmissibility, and the ability to survive for a long time in the environment requires special attention and modification to the existing infection control measures which are highlighted here. In conclusion, a modified infection prevention and control (IPC) regime will protect the dental practitioner, assistant and staff, patients and the community. During the pandemic, drastic measures are necessary, however, during an endemic period measures can be remodified as necessary.