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

Microbiological evaluation of ultraviolet C light-emitting diodes for disinfection of medical instruments

Background

Despite the many guidelines for reprocessing of medical instruments, challenges persist such as microbial resistance to biocides, corrosive effects on materials, and time-consuming reprocessing procedures. Ultraviolet (UV) C light-emitting diode (LED) chambers might provide a solution but the integration in healthcare is still in its infancy. Here, we evaluated the efficacy of a novel ZAPARAY™ UVC LED chamber as a time and energy-efficient alternative for reprocessing of medical instruments for which current disinfection protocols exhibit limitations.

Methods

We verified the disinfection efficacy of the UVC LED chamber on a Petri dish and contaminated several medical devices with Staphylococcus aureus ATCC 25923. The bacterial reduction was assessed after 5 min of UVC LED exposure. Additionally, we investigated the impact of rinsing before UVC exposure.

Results

We demonstrated a bacterial reduction of 9 log10 on a Petri dish. Non-rinsed dental tools exhibited varied reduction levels ranging from a 3.23 log10 to a 6.25 log10 reduction. Rinsing alone yielded an average reduction of 2.7 log10 and additional UVC exposure further reduced the bacterial load by an average of 3.65 log10. We showed an average 4.90 log10 reduction on thermistors, 2 log10 or less on orthodontic pliers, and no reduction on handpieces.

Conclusions

This study demonstrates that UVC LED chambers may be used as a standardized substitute for specific (manual) disinfection procedures of certain medical devices, offering a time-efficient and more sustainable alternative. However, its use should be preceded by efficacy testing for each specific type of instrument.

Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study

AIM

To compare the effect of different ultraviolet-C (UV-C) light exposure times on the dimensional stability of addition silicone dental impressions.

MATERIALS AND METHODS

The dimensional stability of the addition silicone dental impressions was assessed by measuring specific dimensions on dental casts that were recovered from an upper acrylic resin model of dental implants. The impressions were reproduced using a customized tray adapted in a three-point simplex dental articulator permitting only opening and closing movements. Addition silicone dental impressions were divided into five groups (N = 12) according to the UV-C light exposure time. Group A was untreated; group B received 10 minutes; group C, 20 minutes; group D, 30 minutes; and group E, 40 minutes. All the impressions were poured with type IV dental stone and the internal edges of the upper silicone retainers of impression copings were used as five reference points (E, D, C, B, and A) to determine six linear measurements between ED, CB, EA, AD, EB, and CD points using a traveling microscope of 0.001 mm accuracy. One-way analysis of variance (ANOVA) was used for the statistical analysis (p < 0.05).

RESULTS

Expansion and contraction were noted among ED, CB, EA, and EB measurements, whereas only expansion was noted among AD and CD measurements. The ANOVA analysis showed there was no significant difference in the arithmetic means for the measurements between and within group A and the other groups (p > 0.05).

CONCLUSION

The UV-C light exposure time of 10, 20, 30, and 40 minutes did not have any negative effect on the dimensional stability of the addition silicone dental impressions evaluated.

CLINICAL SIGNIFICANCE

In the daily routine dental practice, dental impressions need to be washed and disinfected immediately after making to prevent cross-infections. The UV-C light has been proposed as a promising method for disinfection, but only a few studies have been published about its effect on the dimensional stability of dental silicones. How to cite this article: Bravo-Cueto AG, Tinedo-López PL, Malpartida-Carrillo V. Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study. J Contemp Dent Pract 2024;25(6):507-513.

The Pterygomandibular Space: A Volumetric Evaluation Using the Novel A-Silicone Injections Method

Inferior alveolar nerve block (IANB) is one of the most common procedures in operative dentistry, and a deep understanding of the normal anatomical variation of the pterygomandibular space (PM) is essential for its safe and successful administration. This cadaveric anatomical study aimed to use A-silicone injections to evaluate the volume of the PM. This study was conducted using 46 human cadaver heads (25 males and 21 females). A craniometric analysis was performed using the cadavers' ages, the number of silicone cartridges (carpules) used to fill the pterygomandibular space, Izard's Facial Index (FI), and the Cranial Index (CI). A Halstead mandibular block was performed by injecting 1.7 mL A-silicone cartridges (as an equivalent to standard local aesthetic carpules volume) into the PM. The cured silicone was extracted from the dissected mandibles. The volume (length, width, and thickness) of the extracted silicone and the number of silicone cartridges used to fill the space were evaluated. The results showed that there are statistically significant positive correlations between the CI and the width of the right PM, as well as the width and length of the left PM. A statistically significant correlation was found between the width of the left PM and the age of the cadaveric heads; the higher the age, the thicker the space on both sides. The volume of the PM corresponded to 1.5 cartridges on average.

Photoactivated disinfection procedure for denture stomatitis in diabetic rats

Objective

To study the efficacy of PADTM Plus-based photoactivated disinfection (PAD) for treating denture stomatitis (DS) in diabetic rats by establishing a diabetic rat DS model.

Methods

The diabetic rat DS model was developed by randomly selecting 2-month-old male Sprague-Dawley rats and dividing them into four groups. The palate and denture surfaces of rats in the PAD groups were incubated with 1 mg/mL toluidine blue O for 1 min each, followed by a 1-min exposure to 750-mW light-emitting diode light. The PAD-1 group received one radiation treatment, and the PAD-2 group received three radiation treatments over 5 days with a 1-day interval. The nystatin (NYS) group received treatment for 5 days with a suspension of NYS of 100,000 IU. The infection group did not receive any treatment. In each group, assessments included an inflammation score of the palate, tests for fungal load, histological evaluation, and immunohistochemical detection of interleukin-17 (IL-17) and tumor necrosis factor (TNF-α) conducted 1 and 7 days following the conclusion of treatment.

Results

One day after treatment, the fungal load on the palate and dentures, as well as the mean optical density values of IL-17 and TNF-α, were found to be greater in the infection group than in the other three treatment groups (P < 0.05). On the 7th day after treatment, these values were significantly higher in the infection group than in the PAD-2 and NYS groups (P < 0.05). Importantly, there were no differences between the infection and PAD-1 groups nor between the PAD-2 and NYS groups (P > 0.05).

Conclusions

PAD effectively reduced the fungal load and the expressions of IL-17 and TNF-α in the palate and denture of diabetic DS rats. The efficacy of multiple-light treatments was superior to that of single-light treatments and similar to that of NYS.

Evaluation of the effect of chemical disinfection and ultraviolet disinfection on the dimensional stability of polyether impression material: an in-vitro study

BACKGROUND

Various methods, chemical and physical, disinfect dental impressions. Common chemicals include 1% Sodium Hypochlorite and 2% glutaraldehyde, while UV radiation is a prevalent physical method. Few studies compare their effects on dimensional stability in polyether impressions. This study aims to assess such stability using different disinfection methods. Therefore, this study was planned to evaluate the dimensional stability of polyether impression material using different disinfection methods.

METHODS

This in vitro study compared the effects of chemical disinfectants (1% Sodium Hypochlorite and 2% glutaraldehyde) and UV irradiation on the dimensional stability of polyether impression material. Groups A, B, C, and D, each with ten samples (N = 10), were studied. Group A was untreated (control). Group B was treated with 2% glutaraldehyde for 20 min, Group C with 1% Sodium Hypochlorite for 20 min, and Group D with UV rays for 20 min. A pilot milling machine drill was used to make four parallel holes labeled A, B, C, and D in the anterior and premolar regions from right to left. After sequential drilling, four implant analogs were positioned using a surveyor for accuracy. Ten open-tray polyether impressions were made and treated as described in the groups, followed by pouring the corresponding casts. Distortion values for each disinfection method were measured using a coordinate measuring machine capable of recording on the X- and Y-axes.

RESULTS

A comprehensive analysis was conducted using the one-way ANOVA test for distinct groups labeled A, B, C, and D, revealing significant differences in the mean distances for X1, X2, X4, X5, and X6 among the groups, with p-values ranging from 0.001 to 0.000. However, no significant differences were observed in X3. Notably, mean distances for the Y variables exhibited substantial differences among the groups, emphasizing parameter variations, with p-values ranging from 0.000 to 0.033. The results compared the four groups using the one-way ANOVA test, revealing statistically significant distance differences for most X and Y variables, except for X3 and Y4. Similarly, post-hoc Tukey's tests provided specific pairwise comparisons, underlining the distinctions between group C and the others in the mean and deviation distances for various variables on both the X- and Y-axes.

CONCLUSIONS

This study found that disinfection with 1% sodium hypochlorite or UV rays for 20 min maintained dimensional stability in polyether impressions.

Efficacy of Ozone, UV Radiation, Herbal and Glutaraldehyde Method for Sterilisation of Elastomeric Impression Materials for Orthodontic and Prosthodontic procedures

Objectives

The objectives of the current study was to evaluate the disinfection efficacy of ozone, ultraviolet (UV) radiation, herbal and glutaraldehyde method for sterilization of elastomeric impression materials.

Materials and Methods

Disinfection of elastomeric impression material was performed with each of the disinfection methods: ozone, UV radiation, herbal, and glutaraldehyde. Later microbiological analysis was performed and the colony-forming units were evaluated and compared.

Results

The highest disinfection efficacy was found with glutaraldehyde, followed by ozone and UV radiation, and the least with neem herbal rinse. Intergroup comparison was highly significant.

Conclusion

Dry gaseous ozone and UV radiation can be used effectively for the disinfection of impressions.

Knowledge about methods of disinfection of dental impression among dentists from Ecuador post SARS-COV-2 pandemic

Purpose

The aim of this study is to evaluate the understanding of the management of methods and practices of disinfection of dental impressions applied by general dentists and specialists in oral rehabilitation, post SARS-COV-2 pandemic.

Introduction

The oral cavity has a favorable environment for the growth and multiplication of bacteria and viruses, serving as the gateway to viruses such as SARS CoV-2 virus. Given that patients may be hosts of this infectious disease, stricter biosecurity measures in dental offices and a better understanding of the disinfection processes of dental impressions should be considered in addition to avoiding cross-infections, which are very common in our work environment.

Materials and methods

Descriptive, analytical, survey with the topic "Methods and practices of disinfection of dental impressions" that was composed of 14 questions based in OHPD (Oral Health Preventive Dentistry), n = 452 respondents who met the following inclusion criteria: general practice dentists from Ecuador who actively take dental impressions, specialists in oral rehabilitation with 5 years of experience, surveys with information of complete items, n = 270 professionals; n = 192 general dentists, dental hygienist and n = 78 oral rehabilitation specialists.

Results

n = 270 professionals evaluated, with a mean of p = 0.0. At 426 responses with a p value of <0.05, 30.4 % of responses indicated ignorance in the management of dental impressions, with a standard deviation of 2.744, with significant differences between professions (p = 0.035) and higher average knowledge of sample management within specialist dentists, (Chi p = 0.410 p > 0.05).

Conclusion

The understanding of the management of dental impressions among general dentists and specialists in oral rehabilitation is limited.

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.

The Importance of Chitosan Coatings in Dentistry

A Chitosan is a copolymer of N-acetyl-D-glucose amine and D-glucose amine that can be easily produced. It is a polymer that is widely utilized to create nanoparticles (NPs) with specific properties for applications in a wide range of human activities. Chitosan is a substance with excellent prospects due to its antibacterial, anti-inflammatory, antifungal, haemostatic, analgesic, mucoadhesive, and osseointegrative qualities, as well as its superior film-forming capacity. Chitosan nanoparticles (NPs) serve a variety of functions in the pharmaceutical and medical fields, including dentistry. According to recent research, chitosan and its derivatives can be embedded in materials for dental adhesives, barrier membranes, bone replacement, tissue regeneration, and antibacterial agents to improve the management of oral diseases. This narrative review aims to discuss the development of chitosan-containing materials for dental and implant engineering applications, as well as the challenges and future potential. For this purpose, the PubMed database (Medline) was utilised to search for publications published less than 10 years ago. The keywords used were "chitosan coating" and "dentistry". After carefully selecting according to these keywords, 23 articles were studied. The review concluded that chitosan is a biocompatible and bioactive material with many benefits in surgery, restorative dentistry, endodontics, prosthetics, orthodontics, and disinfection. Furthermore, despite the fact that it is a highly significant and promising coating, there is still a demand for various types of coatings. Chitosan is a semi-synthetic polysaccharide that has many medical applications because of its antimicrobial properties. This article aims to review the role of chitosan in dental implantology.

Effect of chemical disinfection on the dimensional stability of polyvinyl ether siloxane impression material: a systemic review and meta-analysis

BACKGROUND AND OBJECTIVES

Polyvinyl ether siloxane (PVES) possesses ideal characteristics for making precise and accurate dental impressions. PVES dimensional stability owes to its better polymeric properties derived from its parent materials poly ethers and polyvinyl siloxanes. As recommended use of chemical disinfecting agents is getting more popular, there is a growing concern associated with the effect of disinfectants on PVES dimensional stability. This study was aimed to understand the PVES behavior when subjected to chemical disinfectants.

MATERIALS AND METHODOLOGY

The data was collected from research studies retrieved from Google Scholar, Scopus, and PubMed using MeSH terms of keywords "vinyl polyether siloxane AND Disinfection" or (Vinyl polyether siloxane OR polyvinyl siloxane ether OR PVES) AND (disinfectant OR disinfection)" without any restriction to publication date. The PRISMA (Preferred Reporting Items for Systemic Review and Meta-Analysis) directions were observed during the data collection, screening of studies, and meta-analysis. The primary data were retrieved, and batch exported from databases using Harzing's Publish or Perish software; primary analysis was performed in Microsoft Excel, while statistical analysis for effect size, two-tailed p-values, and heterogeneity among studies was performed using Meta Essentials. The effect size was calculated using Hedge's g values at the 95% confidence level using the random-effects model. Heterogeneity among studies was measured using the Cochrane Q and I².

RESULTS AND CONCLUSION

Dental impressions made from the PVES elastomeric impression materials showed no significant changes in dimensional stability. Immersion in the chemical disinfectant for 10 min was associated with clinically irrelevant changes in the dimensions of the PVES impressions. Disinfection with sodium hypochlorite was associated with clinically significant changes in dimensions, with a two-tailed p-value of 0.049. Disinfection with 2-2.5% glutaraldehyde solution was not associated with any significant dimensional variability.

Efficacy Ozone Therapy in Reducing Periodontal Disease

The aim of this study is to highlight the properties of ozone as an aid to non-surgical therapy compared to non-surgical therapy alone. This study included thirty Caucasian patients (eighteen women and twelve men) aged between 35 and 65, recruited at the Oral Hygiene and Prevention Center of the Dental Clinic of the Vita-Salute San Raffaele University, at the San Raffaele hospital in Milan. The periodontal probing was recorded with a PC-PUNC 15 manual probe (Hu Friedy) at time 0; the scaling and root planing session was performed at T1 with or without the aid of ozone therapy, and then, the patients were re-evaluated at one month (T2), three months (T3), and six months (T4). The results obtained show that there are not statistically significant differences in terms of reduction in clinical periodontal indices such as plaque, bleeding, and pocket depth between the two groups. Therefore, treatment with ozoral gel would not seem to improve non-surgical periodontal therapy alone. However, clinical periodontal indices significantly improved in patients treated with non-surgical therapy and ozone gel. From this point of view, ozone gel can be used as an aid to non-surgical therapy due to its excellent characteristics, in particular, its powerful virucidal action.

Caries-affected dentin disinfection using Triphala, Indocyanine green, and Potassium Titanyl Phosphate laser and their effect on adhesive bond strength

AIM

To assess the impact of new cavity sterilization types using ozone water (OW), Potassium Titanyl Phosphate laser (KTPL), Triphala, and indocyanine green photosensitizer (ICGP) on adhesive bond strength.

MATERIALS AND METHODS

Fifty human permanent molars were included based on the criteria of International Caries Detection and Assessment System (ICDAS) scores 4 and 5 visual examinations, surface hardness valuation, staining by a caries detector solution, and radiographs. Caries-affected dentin (CAD) samples were randomly distributed into groups based on methods of disinfection (n = 10). Group 1: chlorhexidine, group 2: ow, group 3: KTPL, group 4: Triphala, and group 5: ICGP. Following disinfection, specimens were applied with Adper prime and bond NT and then restored with resin composite. All specimens were positioned in a jig of the universal testing machine for shear bond strength (SBS). The debonded samples were analyzed under a stereomicroscope at 40x magnification to determine the type of failure. Analysis of variance (ANOVA) and Tukey HSD tests were used keeping the level of significance p < 0.05.

RESULTS

The highest bond of adhesive resin was displayed by group 2 specimens cleaned using OW (16.71 ± 0.19 MPa). Whereas, the lowest bond integrity was observed by group 5 specimens disinfected using ICGP (11.21 ± 0.16 MPa). It was observed samples disinfected with OW (16.71 ± 0.19 MPa) in group 2 and samples in group 4 (16.09 ± 0.26 MPa) treated with Triphala displayed comparable outcomes of bond strength (p > 0.05). It was observed that group 2 (70%) and 4 (80%) treated specimens accounted mostly for cohesive failure. However, groups 1 (80%), 3 (60%), and 5 (70%) displayed an adhesive failure pattern.

CONCLUSION

OW and Triphala displayed better bond integrity of adhesive resin to CAD and therefore have the potential to be used as a cavity disinfectant in clinical settings. However, ICGP and KTPL displayed weak bonds of adhesive to CAD. More work is needed to extrapolate the findings of the present study.

Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

AIM

This study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS.

METHODS

Ninety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined.

RESULTS

SBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05).

CONCLUSION

The bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

Disinfection of polyvinyl siloxane impression material using ozone gas, 0.1% riboflavin, glutaraldehyde, and microwave irradiation and their effect on physical properties

AIM

To assess the antimicrobial effect of ozone gas (OG) 0.1% riboflavin (RF), glutaraldehyde (GaH), and microwave irradiation (MI) on Polyvinyl siloxane impression material formerly colonized with E. coli, P. Aeruginosa, E. faecalis, and S.aureus and their effect on the physical properties MATERIAL AND METHODS: One hundred disk-shaped specimens (diameter 10 mm and thickness 3 mm) were developed by using polyvinylsiloxane impression material and inoculated by the American Type Culture Collection (ATCC) of E. coli, P. aeruginosa, E. faecalis, and S.aureus in an in-vitro setup. The samples were arbitrarily isolated into five groups and subjected for 3 min to the designated disinfection modality. Group 1 Control, group 2: GaH, group 3: 0.1% RF, group 4: MI, and group 5 OG. Following decontamination, the physical properties (contact angle, strain-in-compression, and tear strength) of impression materials were evaluated. Statistical analysis for CFU/mL (log10) for exposed E. coli, P. aeruginosa, E. faecalis, and S.aureus was performed by using analysis of variance (ANOVA) and Tukey's multiple comparison tests at a p-value of less than 0.05.

RESULTS

The most effective antimicrobial efficacy for impression disinfection against all scrutinized microbial colonies were displayed by group 5 OG and the lowest disinfection effectiveness was unveiled by the control group with no treatment. The intragroup comparison revealed that impression disinfection with GaH, MI, and ozone corroborated analogous antimicrobial efficacy(p > 0.05). The disinfecting capacity of the impression material with 0.1% RF was significantly less than MI, GaH, and OG (p < 0.05).

CONCLUSION

Disinfection of polyvinyl siloxane impression material with ozone gas, microwave irradiation, and glutaraldehyde demonstrated reasonable antimicrobial efficiencies against E. coli, P. aeruginosa, E. faecalis, and S.aureus with no detrimental effects on the physical properties of impression material. More studies are advocated to extrapolate the findings of the present study.

Effects of Various Disinfection Methods on the Material Properties of Silicone Dental Impressions of Different Types and Viscosities

There is an ongoing search for novel disinfection techniques that are not only effective, cheap, and convenient, but that also do not have adverse effects on the properties of dental impressions. We compared the effects of various methods (UVC, gaseous ozone, commercial solution, and spray) on the dimensional change, tensile strength, and hardness of silicone impressions. Moreover, as a secondary aim, we performed a statistical comparison of the properties of nondisinfected addition (Panasil Putty Soft, Panasil monophase Medium, Panasil initial contact Light) and condensation silicones (Zetaplus Putty and Oranwash L), as well as a comparison of materials of various viscosities (putty, medium-bodied, and light-bodied). Our results revealed that addition silicones had higher dimensional stability, tensile strength, and Shore A hardness compared to condensation silicones. Both traditional (immersion and spraying) and alternative methods of disinfection (UVC and ozone) had no significant impact on the tensile properties and dimensional stability of the studied silicones; however, they significantly affected the hardness, particularly of Oranwash L. Our study demonstrated that, similarly to standard liquid disinfectants, both UVC and ozone do not strongly affect the material properties of most silicones. However, before recommendation, their usefulness for each individual material should be thoroughly evaluated.