In vitro antimicrobial activity of irreversible hydrocolloid impressions against 12 oral microorganisms

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.

Chlorhexidine as a Disinfectant in the Prosthodontic Practice: A Comprehensive Review

INTRODUCTION

Controlling the cross-contamination between the dental clinic and laboratory is of utmost importance to maintain the health of dental healthcare personnel (DHCP) and patients. The aim of this paper was to review the current literature with regard to the use of chlorhexidine as a prosthetic disinfectant in prosthodontic practice.

MATERIALS AND METHODS

A scoping review of the literature was performed in Medline/PubMed, Ovid Embase, and the Cochrane Library. A search for all literature published from 1980 to 2021 was based on the following keywords: ['Chlorhexidine/gluconate' OR 'chlorhexidine', OR 'gluconate', OR 'denture disinfectants', OR 'antimicrobial', OR 'disinfectant', OR 'impression disinfectants, OR prosthesis' OR 'biofilm, microbiology'] OR [teeth]. We reviewed the disinfectant in terms of its mechanism of action, antimicrobial effectiveness, disinfection techniques, clinical applications, corrosiveness/damage to the structure of prostheses, and reasonable shelf life.

RESULTS

Chlorhexidine was tested under different concentrations ranging from 0.2 to 5%. It provided a significant reduction in biofilm viability but had a minimum effect on Candida albicans with a variable effect result that showed no significant differences in the dimensional changes by immersion of alginate dental impressions for no more than 10 minutes and no clinically significant dimensional differences on aluwax, polyether, condensation siloxane, and polyvinyl siloxane were noticed. Nonetheless, chlorhexidine altered the surface of the silicone and acrylic resins and affected the long-term hardness of the relining material.

CONCLUSION

Within the limitations of this review, the use of chlorhexidine disinfectant demonstrates a good measure in the reduction of contamination and cross-infection and has a minimal effect on the dimensional stability of most impression materials. Further studies with in-vitro testing are required to confirm these findings.

Evaluation of Antimicrobial Efficacy of UVC Radiation, Gaseous Ozone, and Liquid Chemicals Used for Disinfection of Silicone Dental Impression Materials

Effective disinfection of dental impressions is an indispensable requirement for the safety of dental personnel and patients. The ideal method should be not only effective but also convenient, cheap, and environmentally friendly. This study aimed to reliably evaluate the efficacy of ultraviolet C (UVC) radiation, gaseous ozone, and commercial liquid chemicals used for silicone dental impressions disinfection. These methods were applied to two types of elastomeric impression materials: condensation silicones and addition silicones of various consistency (putty, medium, and light). The antimicrobial effectiveness against Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans was evaluated in vitro by counting colony-forming units (CFU) on the surface of samples. The one-way ANOVA with a Tukey HSD test or the Kruskal–Wallis with a Dunn’s test was performed. The results obtained revealed the efficacy of the proposed methods for disinfection of both C-silicones and A-silicones in most of the studied groups. Only one material (Panasil initial contact Light) was not effectively disinfected after UVC irradiation or ozone application. In conclusion, the potential of each disinfection method should be evaluated separately for each material. Moreover, in further research, the possible influence of the proposed methods on the physical properties of the impression materials should be thoroughly investigated.

Antimicrobial Efficacy of Irreversible Hydrocolloid Impression Impregnated with Silver Nanoparticles Compared to Surface Disinfected Impressions - An In vivo Study

BACKGROUND

Routine disinfection procedures have shown to cause incomplete disinfection and detrimental effects on dimensional properties of the impression. Hence, self-disinfecting impression materials impregnated with antimicrobial agents were developed.

PURPOSE

The purpose is to evaluate the antimicrobial efficacy of silver nanoparticles (AgNPs) impregnated in irreversible hydrocolloid (IH) impression material in in vivo conditions.

MATERIALS AND METHODS

This study comprised of four groups-IH impressions disinfected by immersion in 2% glutaraldehyde, IH impregnated with AgNPs of sizes 80-100 nm and 20-30 nm, nondisinfected impressions as control. Five impressions were made for each group and a total of 20 impression samples were made. The antimicrobial action of each sample was assessed by counting the number of colony forming units and by disc diffusion method.

RESULTS

The results were obtained and the data were statistically analyzed by Kruskal-Wallis test and tabulated. The results revealed that AgNPs of size 80-100 nm when impregnated in irreversible impression material showed effective antimicrobial action.

CONCLUSION

The anti-microbial action of 80-100 nm AgNP impregnated IH impressions is comparable to that of impressions disinfected by immersion in 2% glutaraldehyde for 10 min.

An evaluation of antimicrobial potential of irreversible hydrocolloid impression material incorporated with chitosan

Aim:

To evaluate the antimicrobial potential of irreversible hydrocolloid impression material manipulated using chitosan impregnated solution at various time intervals.

Setting and Design:

Evaluative invivo study design.

Materials and Methods:

Maxillary impressions made for 20 dentulous volunteers using irreversible hydrocolloid impression material manipulated using distilled water as control and using 1% chitosan impregnated solution as test group using stock metal trays with one-week interval. Bacterial samples were collected using dry sterile cotton swab in the mid-palatal region at the time intervals of 0, 10, 20 minutes. Bacterial swabs were inoculated on nutrient agar media and incubated at 37° C for 24 hours. Bacterial colonies were counted with the aid of colony counter.

Statistical Analysis Used:

The resultant data was subjected to statistical analysis using repeated measures ANOVA and independent t test.

Results:

Adding water soluble chitosan to irreversible hydrocolloid impression material resulted in superior antimicrobial activity. With the passage of time there was a significant decrease in the microbial colony count upto 10min (p=0.016). However, the rate of decrease of microbial colony count was statistically insignificant between the samples collected at 10 and 20 min.

Conclusion:

Incorporation of water soluble chitosan to irreversible hydrocolloid impression material showed significant antimicrobial activity in 10 minutes.

Effectiveness of Alcohol and Aldehyde Spray Disinfectants on Dental Impressions

Background

The gold standard for disinfection of dental impressions is by immersion although spray techniques are also available. This study compared the effectiveness of alcohol and aldehyde spray disinfectants on analogue dental impressions in a hospital setting.

Materials and Methods

Impressions were swabbed after removal from the mouth (pre-disinfection) and after spraying (post-disinfection) with either a non-aldehyde alcohol-based disinfectant, Bossklein (Silsden, W Yorks, BD20 0EF, UK) or a glutaraldehyde-based alcohol-free disinfectant, MD520 (Dürr Dental, 74321 Bietigheim-Bissingen, Germany). Swabs were transported to the microbiology laboratory in Amies medium and plated onto sheep blood agar within 2 hrs. Plates were incubated for 3 days at 37°C then at room temperature for 3 days. After incubation, all plates were examined for microbial growth.

Results

A total of 87 impressions were assessed (alginate = 41; poly-vinyl siloxane (PVS) = 31; polyether = 15). The counts were categorized into two groups: no growth or growth present. Post-disinfection contamination was present on six alginate and six PVS impressions but only one polyether impression (x² = 1.27, P > 0.05, NSS). Analysis of post-disinfection growth according to impression and disinfectant found significantly more contaminated PVS impressions with the alcohol-based spray than with the aldehyde spray (x² = 5.37, p < 0.05). Disinfection with the aldehyde-based spray resulted in only two contaminated impressions, both in alginate.

Conclusion

Alcohol-based spray disinfection of dental impressions may be less effective than aldehyde spray and full immersion of impressions is recommended. Careful wetting or soaking of all surfaces of impressions is very important when using a spray.

Development of an Impression Material with Antimicrobial Properties for Dental Application

PURPOSE

To evaluate the antimicrobial activity and physico-mechanical properties of an irreversible hydrocolloid in which nanostructured silver vanadate decorated with silver nanoparticles (AgVO₃ ) was added at various concentrations (0% - control, 2.5%, 5%, and 10% by weight).

MATERIALS AND METHODS

The agar diffusion method (n = 10) was used to evaluate the inhibitory effect on the following species: Streptococcus mutans, Staphyloccocus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. The gelation time, flow capacity and plastic deformation were verified (n = 10). The data were analyzed using the Kruskal-Wallis test followed by the Dunn post-test, or via one-way ANOVA with multiple comparisons with a Bonferroni adjustment depending on the distribution (α = 0.05).

RESULTS

All percentages of the nanomaterial were able to promote the antimicrobial activity of a hydrocolloid, with the formation of an inhibition zone (p < 0.05). In general, there was a dose-dependent effect on antimicrobial activity: higher concentrations of the nanomaterial promoted greater action except in the cases of P. aeruginosa (p < 0.001; F = 51.74) and S. aureus (p < 0.001), where the highest inhibition was for the 2.5% group. No difference was found in the gelation time when the control was compared with the groups with AgVO₃ (p > 0.05). The difference was between the 5% and 10% groups (p = 0.007), and the latter promoted an increase in time. The flow capacity of the hydrocolloid with 5% of AgVO₃ was significantly lower when compared with the control (p = 0.034). The AgVO₃ influenced the plastic deformation (p < 0.001) in such a way that concentrations of 5% (p = 0.010) and 10% (p < 0.001) promoted an increase in this property when compared with the control.

CONCLUSIONS

AgVO₃ can be incorporated into an irreversible hydrocolloid as an antimicrobial agent without promoting adverse effects on physical-mechanical properties when used in concentrations of 2.5%.

Evaluation of Antibacterial Effect and Dimensional Stability of Self-disinfecting Irreversible Hydrocolloid: An in vitro Study

AIM

This study evaluated the antibacterial activity and dimensional stability of irreversible hydrocolloids mixed with different concentrations of chlorhexidine gluconate instead of water.

MATERIALS AND METHODS

Experimental specimens (45 specimens) were prepared and allocated into three groups of 15 each. Group I: Impression material mixed with distilled water served as control. Groups II and III were prepared with 0.12 and 0.2% chlorhexidine gluconate solution, respectively. Specimens in each group were subjected to tests for dimensional stability. For antimicrobial activity, 30 specimens were prepared and allocated into three groups of 10 each named as group I (control), group II (0.12% chlorhexidine gluconate), and group III (0.2% chlorhexidine gluconate) similar to specimens for dimensional stability. Statistical analysis was performed using a one-way analysis of variance (ANOVA) and Tukey test.

RESULTS

Zones of inhibition were observed around test specimens, but not around control specimens; there was a significant intergroup difference in the diameters of the inhibition zones. In the test for dimensional stability, no significant differences were detected among groups, and the accuracy was clinically acceptable.

CONCLUSION

Irreversible hydrocolloid impression material mixed with chlorhexidine exhibits varying degrees of antibacterial activity without influencing the dimensional stability of set material.

CLINICAL SIGNIFICANCE

Many contagious diseases can be prevented by practical control of infection in the dental office. Chlorhexidine gluconate, as a mixing liquid, ensures disinfection of impression, and this method of disinfection is more convenient and avoids extra effort as in other disinfection techniques.

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

Abstract Introduction Obtaining dental models that accurately represent the molded oral tissue requires professional attention, especially when using irreversible hydrocolloid as a molding material. Objective To evaluate the conducts of undergraduate dental students at different internships for the disinfecting procedures, pouring, and storage of irreversible hydrocolloid impressions. Material and method This is an observational, cross-sectional and descriptive study with a census sample of 89 students enrolled in the supervised internships I, II, III and IV. Data collection was performed using a structured questionnaire containing eight questions. Data were analyzed at the 5% significance level. Result Most of the students (88.8%) performed the disinfection procedure, for which the most widely used method (64.6%) was the application of sodium hypochlorite 1% spray stored in a sealed container. The most common disinfection time was 10 minutes (86.1%). Students in the early internships performed better in regard to the proportion of water/plaster to be used compared with students in the final internships. At all internships, pouring and storage of the ensemble of mold and model were neglected during the setting reaction. There was a statistically significant association between the stage and the disinfection method, the ratio of water/powder and pouring of the model (p<0.05). Conclusion Students exhibited appropriate conduct of disinfection; however, they should be encouraged to use evidence-based clinical practices in order to improve the procedures of pouring and storage of irreversible hydrocolloid molds.

Effectiveness of mouthrinses and oral prophylaxis on reduction of microorganisms count in irreversible hydrocolloid impression: an in vivo study

Dental impressions, contaminated with saliva, blood, plaque, are potential source of infection. All impressions should be disinfected after their removal from mouth to prevent cross contamination. Different methods have been tried to disinfect the commonly used irreversible hydrocolloid impression material, but they have been shown to influence the dimensional stability and surface detail of the impression which ultimately affects the precision of the final prosthesis. The aim of this study was to evaluate the efficacy of pre-procedural oral prophylaxis and mouthrinses in reducing the overall microbial load intraorally as well as on alginate impression surface. A total of 60 positive cases selected from 100 subjects who were partially edentulous and above 18 years of age and without medical or pharmacotherapy histories were studied over a period of 18 months, from outpatient clinic of Department of Prosthodontics, GNIDSR. Alginate impressions, before and after prophylaxis were examined microbiologically for the persistence of test microorganisms on the untreated (control group) and the impressions made after treatment. The data were statistically analyzed by the Student t test to assess the effectiveness of the procedure and also the comparative effectiveness of oral prophylaxis and commonly used mouthrinses. The results showed that the impressions were safer when made after oral prophylaxis and/or mouthrinses.

Evaluation of properties of irreversible hydrocolloid impression materials mixed with disinfectant liquids

Background:

Addition of disinfectant to irreversible hydrocolloid impression materials can eliminate the disinfection step to avoid dimensional changes associated with it. The aim of the present study was to evaluate the effect of various disinfectant mixing liquids on the properties of commercially available irreversible hydrocolloid impression materials.

Materials and Methods:

Four commercially available irreversible hydrocolloid impression materials (Zelgan, Vignette, Tropicalgin, and Algitex) were mixed with disinfectant liquid containing chlorhexidine (0.1 and 0.2%) and sodium hypochlorite (0.1 and 0.5%). After mixing with disinfectant liquids, materials were evaluated for pH changes during gelation, gelation time, flow, gel strength, permanent deformation and detail reproduction.

Results:

Significant changes in gelation time were observed in irreversible hydrocolloid impression materials upon mixing with disinfectant liquids. In general, chlorhexidine increased the gelation time, whereas sodium hypochlorite reduced it. However, no significant changes in the flow were observed both with chlorhexidine and sodium hypochlorite. Gel strength was found to decrease when mixed with chlorhexidine, whereas an increase in gel strength was observed upon mixing with sodium hypochlorite. Permanent deformation of the most irreversible hydrocolloid impression materials was below the specification limit even after mixing with disinfectant liquids. Sodium hypochlorite significantly reduced the surface detail reproduction, whereas no change in detail reproduction was observed with chlorhexidine.

Conclusion:

Chlorhexidine solution can be used to mix irreversible hydrocolloid impression materials in regular dental practice as it did not significantly alter the properties. This may ensure effective disinfection of impressions.

Drug and dental impression materials

Guidelines to prevent cross contamination with infectious agents have been instituted for dental clinical and laboratory procedures. However, compliance by dental offices and clinics in disinfecting impression material has not been universal. Techniques for disinfecting impression materials are spraying or immersing impression materials. These techniques can reduce the surface detail and dimensional accuracy of impressions; most disinfectants are irritants. This study reviewed whether antimicrobial activity can be achieved by mixing certain drugs with the impression material and their effects on the disinfection are achieved through such additions.

Comparison of antimicrobial activities and compressive strength of alginate impression materials following disinfection procedure

AIM

This study investigated the effectiveness of disinfecting solution when incorporated into alginate powder instead of water against some microorganisms and on compressive strength of alginate.

MATERIALS AND METHODS

For measuring antimicrobial activity of alginate, 60 alginate specimens were prepared and divided into two groups: One with water incorporated in the mix (control) and the other with 0.2% chlorhexidine digluconate incorporated in the mix instead of water. The tested microorganisms were: gram +ve cocci, gram -ve bacilli and yeast (each group 10 samples). For measuring compressive strength, 20 specimens of alginate were divided into two groups: One with water incorporated in the mix (control) and the other with chlorhexidine incorporated in the mix.

RESULTS

The statistical analysis of antimicrobial efficacy of alginate was performed with Mann-Whitney U-test, which revealed very high significant difference when comparing among groups (p < 0.000). Student t-test analyzed the compressive strength data which revealed nonsignificant difference between groups (p > 0.05).

CONCLUSION

The incorporation of disinfecting agents into impression materials could serve an important role in dental laboratory infection control and it had no adverse effect on compressive strength of the hydrocolloid alginate.

CLINICAL SIGNIFICANCE

The risk of transmitting pathogenic microorganisms to dental laboratories via impression has been considered a topic of importance for a number of years.

Surface detail reproduction and dimensional accuracy of stone models: influence of disinfectant solutions and alginate impression materials

This study compared the surface detail reproduction and dimensional accuracy of stone models obtained from molds disinfected with 2% sodium hypochlorite, 2% chlorhexidine digluconate or 0.2% peracetic acid to models produced using molds which were not disinfected, with 3 alginate materials (Cavex ColorChange, Hydrogum 5 and Jeltrate Plus). The molds were prepared over matrix containing 20-, 50-, and 75-µm lines, performed under pressure with perforated metal tray. The molds were removed following gelation and either disinfected (using one of the solutions by spraying followed by storage in closed jars for 15 min) or not disinfected. The samples were divided into 12 groups (n=5). Molds were filled with dental gypsum Durone IV and 1 h after the start of the stone mixing the models were separated from the tray. Surface detail reproduction and dimensional accuracy were evaluated using optical microscopy on the 50-µm line with 25 mm in length, in accordance with the ISO 1563 standard. The dimensional accuracy results (%) were subjected to ANOVA. The 50 µm-line was completely reproduced by all alginate impression materials regardless of the disinfection procedure. There was no statistically significant difference in the mean values of dimensional accuracy in combinations between disinfectant procedure and alginate impression material (p=0.2130) or for independent factors. The disinfectant solutions and alginate materials used in this study are no factors of choice regarding the surface detail reproduction and dimensional accuracy of stone models.