Disinfection and communication practices: a survey of U.S. dental laboratories

Laboratory Communication for Optimal Patient Outcomes

Laboratory communication in dentistry involves the exchange of detailed information between clinicians and technicians for fabricating restorations, ensuring optimal patient outcomes. Effective communication includes written narratives, photographs, digital scans, and physical materials. Clinicians must understand laboratory processes, while technicians need to interpret and execute requests accurately. Certification and adherence to legal standards are essential. Effective communication impacts patient care by ensuring proper case planning, patient education, and setting realistic expectations. Clear, precise exchanges between clinicians and technicians are crucial for quality and compliance, fostering a collaborative and respectful relationship that ultimately benefits patient care outcomes.

Knowledge, attitude, and practice of dental health professionals toward dental impression disinfection protocol during the COVID-19 pandemic in Saudi Arabia- a cross-sectional study

BACKGROUND

Despite the updated guidelines on dental impression disinfection protocols during the COVID-19 pandemic, adherence to such procedures has not been studied among dental health professionals in Saudi Arabia. Understanding DHPs' knowledge, attitudes, and practices regarding COVID-19 is crucial in assessing a willingness to adhere to the recommendations provided by health authorities in mitigating the spread of COVID-19 via dental impressions impacting patient safety and infection control measures. Hence, this study aimed to assess dental health professionals' (DHPs) knowledge, attitudes, and practices (KAP) toward dental impression disinfection protocol during the COVID-19 pandemic in Saudi Arabia.

METHODS

A cross-sectional study using an online survey was conducted from 14 December 2022 to 21 March 2023 among practicing dentists, dental assistants (DA), dental laboratory technicians (DT), and dental hygienists in Saudi Arabia. A validated and reliable questionnaire that consisted of 38 items along with demographic variables was prepared to collect the data. Using Google Forms, a questionnaire link was prepared and shared on the social media platforms of DHPs in Saudi Arabia. A descriptive analysis was conducted to report the percentages and frequencies. The mean knowledge, attitude, and practice scores were analyzed using an Independent t-test, ANOVA, and Pearson's correlation tests.

RESULTS

A total of 718 DHPs voluntarily participated in the survey. Most of the DHPs exhibited average knowledge 392 (54.6%), neutral attitudes 393(54.7%), and adequate 549 (76.5%) practice towards dental impression disinfection protocol. The mean knowledge score differed significantly across nationality (p = 0.013), type of DHPs (p < 0.001), qualification (p = 0.045), and experience (p = 0.028) of the study participants. Significant differences in attitude towards impression disinfection were observed in different age groups (p = 0.002), qualifications (p = 0.015), and experiences (p = 0.024) of the DHPs. Similarly, practice varied across different age groups (p = 0.010), nationality (p = 0.013), type of DHPs (p = 0.019), qualification (p = 0.044), experience (p = 0.041), and COVID-19 Infection (p = 0.006). Moreover, a significant positive correlation between knowledge-attitude (r = 0.258, p < 0.01), knowledge-practice (r = 0.283, p < 0.01), and attitude-practice (r = 0.196, p < 0.01) was observed.

CONCLUSION

DHPs considered in this study demonstrated average knowledge and attitudes toward impression disinfection, requiring improvement through continuous dental education and training. However, they displayed acceptable dental impression disinfection practices during the COVID-19 pandemic. It is highly recommended that continuing education programs should mainly reinforce the knowledge of sodium hypochlorite, iodophor, and phenolics and their concentrations to be used as an impression disinfectant. Additionally, it should focus on techniques of disinfecting elastomeric, hydrocolloid, zinc oxide and eugenol, and impression compound materials to mitigate the spread of COVID-19 based on Saudi ministry of health guidelines.

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 Photodynamic Therapy as a Technique for Decontamination of Acrylic Resin Devices Provided by Different Dental Laboratories

Introduction: Dentures, occlusal splints, surgical guides and orthodontic appliances are examples of acrylic resin devices made in dental laboratories, which must be disinfected and even sterilized before insertion into the oral cavity. This study evaluated the antimicrobial effect of photodynamic therapy (PDT) applied to acrylic resin specimens received from different laboratories. Methods: Three hundred standardized specimens were ordered from six randomly selected laboratories registered in the Council of Dentistry of Ceará (n=50). The PDT consisted in the association of 22 µM erythrosine, as a photosensitizer (P), and a 520-nm LED at 38 J/cm² (L). The specimens of each laboratory were randomly distributed into five groups: positive control, sterilized with ethylene oxide; negative control, untreated (P-L-); erythrosine control, only stained (P+L-); LED control, only irradiated (P-L+); PDT (P+L+). Then, the specimens were individually sonicated in saline solution; the suspension was diluted, plated on culture mediums (blood agar, sabouraud dextrose agar and a non-selective chromogenic agar), and incubated for 48 hours at 37°C. Colony-forming-unit (CFU) counts were done and statistical tests of Kruskal-Wallis/Dunn were carried out. Results: The specimens from all laboratories were contaminated with bacteria and yeasts. Staphylococcus aureus, Staphylococcus saprophyticus, Escherichia coli, Enterococcus spp., Klebsiella and Pseudomonas spp. were identified. The PDT significantly reduced CFU counts (P<0.0001), compared to P-L-. Conclusion: PDT was able to effectively decontaminate the acrylic resin specimens provided from dental laboratories.

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.

Current overview for chemical disinfection of dental impressions and models based on its criteria of usage: A microbiological study

Objectives

The aims of this study were to compare the efficacy of two proven chemical disinfectants, glutaraldehyde and povidone iodine on dental impression and models by determining the reduction in the microbial load, and to compare changes in the physical properties of the models after adding the disinfectants.

Materials and Methods

Irreversible hydrocolloid upper impressions of 90 patients were made and divided into 3 groups of 30 samples each; Group A--Control group; Impressions were run under clean tap water before pouring the model. Group B--2% Glutaraldehyde sprayed on the impression and left in situ for 10 min before pouring the model. Group C -10 ml of (5%) povidone iodine incorporated into the gypsum before pouring the model. Models from all three groups were subjected to microbiological assessment at three different time intervals, T0--24 h, T1--1 month and T2--3 months of storage by comparing the colony forming units (CFUs) of bacteria and fungi. The compressive strength of 5 models from each group was also analyzed in Newton's/mm².

Results

2% Glutaraldehyde proved more effective than povidone iodine after 24 h of storage (T1), however at the end of 1 month (T1) and 3 months (T2) the Povidone group showed the maximum disinfection. Both the disinfectants caused a reduction in the compressive strength of the model with the povidone iodine group showing the maximum reduction.

Conclusion

Although povidone iodine was the most effective disinfectant after 3 months, it showed a significant reduction in the compressive strength and caused discoloration of the model. 2% Glutaraldehyde proved to be the choice of disinfectant with minimal adverse effects.

Knowledge and practices about sterilization and disinfection

Aims

The aim of the present study was to evaluate the knowledge and practices employed for infection control in dental laboratories.

Materials and Methods

A preformed questionnaire comprised of 16 questions related to infection control measures was prepared. This questionnaire based survey was then conducted among dental technicians of 60 dental colleges in East India. Data were then recorded and analyzed.

Results

Majority of impressions/prosthesis were carried in plastic bags (93.8%) by laboratory attendants to the laboratory. The responses revealed that majority of impressions were received after wearing gloves (54.6%) from dental attendant. Majority of dental technicians (78.1%) admitted in their responses that they are not aware of infection control measures taken in dental laboratory. Only 32.8% technicians were found to practice disinfection procedure after receiving impression/prosthesis in laboratory from dental operatory. Among protective wears, 70.3%, 95.3%, 32.8%, and 92.2% technicians were found to use gloves, Apron, eye shield, and face mask, respectively. Among all respondents, 59.3% were found to be vaccinated for hepatitis B vaccine.

Conclusion

There is lack of knowledge and motivation among dental technician to practice infection control measures in dental laboratories of dental institutes in North India.

Online audiovisual resources for learning the disinfection protocol for dental impressions: A critical analysis

STATEMENT OF PROBLEM

Mainly because of poor training, substandard impression disinfection practices have been reported worldwide.

PURPOSE

The purpose of this cross-sectional study was to assess the extension, usefulness, and reliability of contents on this topic available on the main video websites for self-training.

MATERIAL AND METHODS

An analysis of the YouTube, Vimeo, and Dailymotion websites was undertaken in February 2018. The exclusion criteria were animal procedures, non-English language videos, advertisements, videos exclusively redirecting to websites, soundless videos, duplicated videos, and videos reporting on a research project. Information extension was assessed in 6 nonmutually exclusive dimensions, and usefulness was evaluated by using a 10-item scale. Reliability was assessed on a reliable or nonreliable basis. Statistical analyses were undertaken by using the Mann-Whitney and Fisher exact tests.

RESULTS

Of 386 identified videos, only 22 met the selection criteria, mostly published by health-care professionals (n=8; 36.4%). Most videos had less than 3000 views. Median usefulness score: 3 (IR: 3-3; range: 0-6). No video included all 7 topics considered in the index (median 3; IR: 2.25-3; range: 0-4). Just 5 clips (22.7%) described a procedure according to the American Dental Association and Center for Disease Control (ADA and CDC) guidelines.

CONCLUSIONS

Audiovisual online resources on dental impression disinfection includes incomplete information with limited usefulness and reliability. The number of views was not related to quality, and therefore, many viewers may be obtaining knowledge from substandard material.

Comparative evaluation of elastic recovery of three different elastomeric impression materials on chemical disinfection and autoclaving: An in vitro study

Aim:

The aim of the study was to investigate the effect of disinfection and steam autoclaving on the elastic recovery of three different elastomeric impression materials.

Settings and Design:

In vivo - comparative study.

Materials and Methods:

Ninety dumbbell-shaped specimens of commercially available two addition-cured silicones (AFFINIS and AQUASIL) and one condensation-cured silicone (SPEEDEX) impression materials were prepared and treated with chemical disinfectant and steam autoclaving. Specimens were seal packed and sent to laboratory for testing elastic recovery. After the specimen had been pulled to failure, the broken parts were fitted back together, and the distance between the marks was measured using an electronic Vernier caliper.

Statistical Analysis Used:

one-way analysis of variance test and Tukey post hoc test for multiple comparisons.

Results:

The result showed significant difference in elastic recovery of AFFINIS when it was disinfected and steam autoclaved whereas elastic recovery showed no significant difference when SPEEDEX and AQUASIL were disinfected and steam autoclaved. Similarly, results were alike when AFFINIS, SPEEDEX, and AQUASIL were compared on disinfection. However, significant difference was noted on steam autoclaving, highest being the mean value of AFFINIS.

Conclusion:

Within the limitations of this in vitro study, conclusion was made that the elastic recovery of AFFINIS was the least which improved with disinfection and autoclaving. Elastic recovery of SPEEDEX and AQUASIL was similar. However, all the three materials used in the study can be safely sterilized after clinical use and before being sent to the laboratory without significantly affecting their elastic recovery.

Disinfection of dental impressions: knowledge and practice among dental technicians

Background: Dental impressions are a common source for transmission of infection between dental clinics and dental labs. Dental impressions can be cross-contaminated by patient's saliva and blood, which then cross-infect the dental casts poured from the impressions. Objective: To evaluate the current practices of disinfection of dental impressions and their protocols and to assess the knowledge of cross-infection control among dental technicians in Jordan. Method: Dental technicians (n=85) completed a self-administered questionnaire about their practices of disinfection for dental impressions. Results: The distribution of dental technicians was 63.8% fixed prosthodontics, 23.5% removable prosthodontics, 7.8% orthodontics, and 4.8% maxillofacial prosthodontics. The majority of the laboratories did not have instructions related to disinfection of impressions. About 50% of technicians were vaccinated against HBV. About 44.7%, and 42.9% of labs reported that they never disinfect alginate or silicon impressions, respectively. In addition, the majority of lab owners (53%) believed that the dentist should disinfect the impressions before shipping them to dental laboratories, while (45%) believed that disinfecting the impressions is the responsibility of the dental assistant. Moreover, about 38% of this study population reported not using gloves in their labs. In those labs were disinfection was used, 51% used spray disinfection whereas 32.6% used immersion disinfection. The cost of disinfectant was ranked as the most important factor (51.3% of the cases) for the dental technician to choose the disinfectant followed by its effectiveness. Conclusion: Dental technician practices in impression disinfection was not satisfactory, therefore, education programs about impression disinfection are needed.

Quality of cross-infection control in dental laboratories. A critical systematic review

Purpose

To identify reported practices for cross-infection control in dental laboratories and to quantify the importance of the flaws encountered.

Data sources

Systematic search (cross-infection AND dental laboratory) at EMBASE, PubMed, SciELO and Scopus databases.

Study selection

Papers reporting on cross-sectional studies providing original data about cross-infection knowledge, practices and attitudes of dental technicians. Papers reporting on a single laboratory or institution were excluded.

Data extraction

Data extraction was undertaken independently by three reviewers using a purpose made form. The outcome of this study was analyzed in five aspects, namely process organization, disinfection, working environment, use of individual protective equipment and vaccination policy.

Results of data synthesis

The systematic search output was 1651 references and 11 papers were finally selected. Flaws were more frequently identified in terms of vaccination policy, biological safety of the working environment and use of individual protective equipment (100%). Slightly better results were found in terms of organization of the cross-infection control process (89.47%) and disinfection practices (85.71%). The application of the formula for disclosing the relative importance of the flaws identified in the literature prioritizes the need for interventions aimed at improving the organization of the cross-infection control procedures, followed by training in item disinfection. The control of the working environment together with the use of individual protective equipments rank closely in importance, followed by the existence of a vaccination policy.

Conclusions

Sub-standard cross-contamination practices seem to be a common finding in dental laboratories, which may well compromise the quality of certain dental treatments.

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.

Experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a novel surfactant compared with commercial VPS

OBJECTIVES

To formulate experimental hydrophilic (Exp) VPS impression materials incorporating a novel surfactant (Rhodasurf CET-2), and to compare their contact angles (CAs) with commercial materials, before/after disinfection.

METHODS

CAs were measured immediately after setting and after disinfection (1% NaOCl; 30min and 24h), together with their change whilst a droplet remained on the materials surface (over 10, 20, 30 60 and 120s), on three commercial (Aquasil Ultra-Monophase [Aq M], Elite HD-Monophase [Elt M], Extrude Medium-bodied [Extr M]) and four experimental (Exp I-IV) materials, using the Drop Shape Analysis 100 technique. The results were compared statistically.

RESULTS

CAs of all experimental materials were within the range of those obtained for the commercial materials, with the exception of Exp-IV, which presented with the lowest CAs at the three time points. The control Exp-I was hydrophobic at all three time points (CAs ∼100+), as was Elite. Immediately after setting, Aq M had low CAs but these increased significantly after 30min of disinfection. After twenty four hours' disinfection CAs of all Exp/commercial VPS increased significantly compared to immediately after setting. The CAs of droplets left on the material (120s) decreased with time, even after disinfection, except for Exp-I.

SIGNIFICANCE

The novel surfactant Rhodasurf CET-2 in Exp-III and IV, is an effective surfactant, retaining a low CA after disinfection, compared with Igepal CO-530 in Aq M. Disinfecting VPS impression materials for more than 30min increases their surface CAs, and therefore prolonged disinfection periods should be avoided.

Infection control knowledge and practice: A cross-sectional survey on dental laboratories in dental institutes of North India

Aim and Objectives

The aim of the study was to assess the knowledge of dental laboratory technicians regarding infection control and modes of infection control employed by them.

Settings and Design

A self-assessment questionnaire-based survey was carried out among dental technicians to assess the knowledge and practice of infection control in dental laboratories.

Materials and Methods

Survey instrument containing 16 questions were randomly distributed to 70 dental colleges of North India regarding knowledge of infection control methods and infection control practised in laboratories. Data were collected and analyzed.

Results

The response showed that 30.76% of dental technicians receive 30-50 or more than 50 impressions in a week. About 96.15% of the technicians used a plastic bag to carry impressions. Twenty-five percent of the dental technicians were aware of infection control protocol. Fifty-five percent of the technicians received impressions while wearing gloves and 61.53% of the institutes had a separate receiving area. Nearly 71.15% of the technicians communicate with the doctor regarding the disinfection of impression received in the laboratory. Almost 30.76% of the dental technicians disinfect all the impressions and 67.30% technicians use immersion for disinfection of impressions. Only 38.46% responded that they immerse impressions for 10 min for disinfection. About 73.07% use gloves, 90.38% use mouth masks, 57.69% wear eye shields, and 88.46% wear aprons while working. Nearly 78.84% of the technicians received vaccination against hepatitis B virus. Almost 69.23% of the technicians change pumice slurry after regular intervals, and 75% do not add any disinfectant. Nearly 59.61% of technicians disinfect the prostheses before sending it to the clinic, and 42.30% disinfect them by immersion technique. About disposal of waste, 80.76% said that they dispose the waste properly.

Conclusion

To summarize, most of the technicians were not aware of basic infection control protocols.

Communication methods and production techniques in fixed prosthesis fabrication: a UK based survey. Part 2: production techniques

Highlights that even though clear guidelines are available, there still seems to be a lack of agreement between dentists and laboratories regarding the disinfection and quality of dental impressions.

Despite the promotion of all-ceramic crowns, this survey indicated that metal-ceramic crowns are still the most frequently prescribed for both anterior and posterior restorations.

Aim The aim of this study was to identify the communication methods and production techniques used by dentists and dental technicians for the fabrication of fixed prostheses within the UK from the dental technicians' perspective. This second paper reports on the production techniques utilised.

Materials and methods Seven hundred and eighty-two online questionnaires were distributed to the Dental Laboratories Association membership and included a broad range of topics, such as demographics, impression disinfection and suitability, and various production techniques. Settings were managed in order to ensure anonymity of respondents. Statistical analysis was undertaken to test the influence of various demographic variables such as the source of information, the location, and the size of the dental laboratory.

Results The number of completed responses totalled 248 (32% response rate). Ninety percent of the respondents were based in England and the majority of dental laboratories were categorised as small sized (working with up to 25 dentists). Concerns were raised regarding inadequate disinfection protocols between dentists and dental laboratories and the poor quality of master impressions. Full arch plastic trays were the most popular impression tray used by dentists in the fabrication of crowns (61%) and bridgework (68%). The majority (89%) of jaw registration records were considered inaccurate. Forty-four percent of dental laboratories preferred using semi-adjustable articulators. Axial and occlusal under-preparation of abutment teeth was reported as an issue in about 25% of cases. Base metal alloy was the most (52%) commonly used alloy material. Metal-ceramic crowns were the most popular choice for anterior (69%) and posterior (70%) cases. The various factors considered did not have any statistically significant effect on the answers provided. The only notable exception was the fact that more methods of communicating the size and shape of crowns were utilised for large laboratories.

Conclusion This study suggests that there are continuing issues in the production techniques utilised between dentists and dental laboratories.

Modification of pH Conferring Virucidal Activity on Dental Alginates

To formulate an alginate dental impression material with virucidal properties, experimental alginate dental impression materials were developed and the formulations adjusted in order to study the effect on pH profiles during setting. Commercially available materials served as a comparison. Eight experimental materials were tested for antiviral activity against Herpes Simplex Virus type 1 (HSV-1). Changing the amount of magnesium oxide (MgO) used in the experimental formulations had a marked effect on pH. Increasing MgO concentration corresponded with increased pH values. All experimental materials brought about viral log reductions ranging between 0.5 and 4.0 over a period of 4 h. The material with the lowest pH was the most effective. The current work highlights the very important role of MgO in controlling pH profiles. This knowledge has been applied to the formulation of experimental alginates; where materials with pH values of approximately 4.2-4.4 are able to achieve a significant log reduction when assayed against HSV-1.

Microbial contamination of laboratory constructed removable orthodontic appliances

OBJECTIVES

This study aims to determine whether laboratory constructed removable orthodontic appliances are free from microbial contamination prior to clinical use and to evaluate the dental hospital cross-infection procedures to ensure that patient-derived contamination does not enter the construction process, thereby propagating a cycle of cross-contamination.

MATERIALS AND METHODS

The construction process of removable orthodontic appliances from three individuals was evaluated at every stage, from impression to final delivery of the appliance using molecular microbiological techniques. The bacterial profiles at each stage of appliance construction were obtained using denaturing gradient gel electrophoresis, along with the bacterial profiles of the three participants' saliva. This enabled the bacterial profiles found at each stage of construction to be compared directly with the saliva of the person for whom the appliance was being constructed. Bacteria were identified at each stage using 16S rDNA PCR amplification and sequence phylogeny.

RESULTS

There was no evidence of bacterial cross-contamination from patients to the laboratory. The current process of disinfection of impression appears to be adequate. Contamination was found on the final removable appliances (0.97 × 10(2)-1.52 × 10(3) cfu ml(-1)), and this contamination occurred from within the laboratory itself.

CONCLUSIONS

Every effort is made to reduce potential cross-infection to patients and dental professionals. Newly constructed removable appliances were shown not to be free from contamination with bacteria prior to clinical use, but this contamination is environmental. Further studies would be required to determine the level of risk this poses to patients.

CLINICAL SIGNIFICANCE

Dental professionals have a duty of care to minimise or eradicate potential risks of cross-infection to patients and other members of the team. To date, much less attention has been paid to contamination from the orthodontic laboratory, so contamination and infection risks are unknown.

Effect of alginate chemical disinfection on bacterial count over gypsum cast

PURPOSE

To evaluate the efficacy of sodium hypochlorite (1 : 10) and iodophor disinfectants on alginate impressions along with their effect on the survived bacterium count on the gypsum cast.

MATERIALS AND METHODS

Four alginate impression on each dentate patients were made, of which Group I were not washed or disinfected, Group II impressions were merely washed with water, Group III were disinfected by spraying with sodium hypochlorite (1 : 10), Group IV were disinfected with iodophor (1 : 213). Gypsum cast (type III) were made from all the impression. Impressions and gypsum cast were swabbed in mid palatal region for bacterial culture. Bacterial colony counting done after 3 days of incubation at 37℃ in blood agar media. The data obtained was analyzed by one way ANOVA test at a significant difference level of 0.05.

RESULTS

Group I and Group II showed significantly more bacteria compared to Group III and Group IV. Bacterial colonies on the alginate impression and gypsum cast in group disinfected with Sodium hypochlorite (1 : 10) were 0.18, 0.82 respectively compared to group treated with iodophor (1 : 213). There was an increase in bacterial count on dental cast compared to source alginate impressions.

CONCLUSION

Sodium hypochlorite (1 : 10) was found to be better disinfectant for alginate impression. There was an indication of increase in number of bacteria from alginate impression to making of dental cast. Additional gypsum cast disinfectant procedures need to be encouraged to completely eliminate cross infection to dental laboratory.

Determinants of Iranian dentists' behaviour regarding infection control

AIM

To evaluate the determinants of Iranian dentists' behaviour regarding infection control (IC).

DESIGN

  A cross-sectional questionnaire survey.

SETTING

Iranian general dental practitioners (GDP) participating in a national dental congress.

METHODS

The GDPs filled in a self-administered questionnaire containing questions regarding their attitudes towards and their behaviour on several aspects of IC. Background factors included GDP's year of birth, gender, and work-related factors. Statistical evaluation employed the Chi-square test, Cronbach alpha, and regression analysis.

RESULTS

  In total, 479 GDPs returned the questionnaire. Their mean age was 38.6years (SD=9.4) and 53% were men. The vast majority of the GDPs had positive attitudes towards the inquired after IC criteria with no statistical difference based on the GDP's background characteristics. Of all respondents, >70% reported that they inform the laboratory about the infection status of the sent items, disinfect impressions before sending to the laboratory, and wash patients' mouths before working with high-speed or ultrasonic devices. Adherence to all the studied IC criteria was reported by 10% of the respondents; more frequently by younger GDPs and those with fewer experience years (P<0.05).

CONCLUSION

Greater emphasis on infection control programmes in dentists' education is called for especially in continuing education.

Disinfection of dental impressions - compliance to accepted standards

INTRODUCTION

The responsibility of ensuring impressions have been cleaned and disinfected before dispatch to the dental laboratory lies solely with the dentist. Uncertainty of impression disinfection risks both the health of the receiving dental technician and potential repeat disinfection of an already disinfected impression with detrimental consequences for its dimensions.

OBJECTIVE

To ascertain, from the perspectives of dentists and dental technicians, current impression decontamination and disinfection practices with, in the case of the technicians, an estimate of the relative prevalence of contaminated voids within apparently disinfected impressions.

DESIGN

Anonymous postal questionnaire.

METHOD

Dentist (n = 200) and dental technician (n = 200) potential participants, selected at random from the registers held by the General Dental Council, were invited to complete an anonymous postal questionnaire that sought to establish current practices and perceived effectiveness of impression disinfection.

RESULTS

Questionnaire return rates of 42.1% and 31.2% were recorded for dentists and dental technicians respectively. A wide range of solutions, at different dilutions of the same product, was used by the dentists to disinfect dental impressions. 37.2% rinsed the impressions with water, and 2.6% always brushed debris away, before disinfection. 24.7% of dentists did not inform the laboratory of disinfection. Irrespective of the disinfection status of the received impressions, 50% of the responding dental technicians disinfected all impressions. 95% of them had received blood-contaminated impressions. 15% had encountered blood-filled voids upon trimming back the peripheries of impressions. 64.7% were confident that the impressions received by them had been disinfected by the dentists.

CONCLUSIONS

Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this.

The effect of disinfection by spray atomization on dimensional accuracy of condensation silicone impressions

BACKGROUND AND AIMS

The condensation silicone impression materials are available, but there is little knowledge of their accuracy after disinfection. The objective of this study was to evaluate the effect of the disinfection by spray atomization on dimensional accuracy of condensation silicone impressions.

MATERIALS AND METHODS

Impressions were made on a stainless steel master model containing a simulated two complete crown preparation with an edentulous space interposed using Spidex® and Rapid® impression materials. 44 impressions were made with each material, of which 16 were disinfected with 5.25% sodium hypochlorite, 16 were disinfected with 10% iodophor and 12 were not disinfected. Three dimensional measurements of working casts, including interpreparation distance, height, and diameter, were calculated using a measuring microscope graduated at 0.001 mm. Dimensional changes (mm) between the disinfected and non-disinfected working casts were compared. One-way analysis of variance (ANOVA) was employed to analyze the data (α=0.05).

RESULTS

Disinfection of each condensation silicone material by spraying atomization with two different disinfectant material resulted in significant change in interpreparation distance (p<0.05). Changes in height and diameter were only significant in Spidex® impressions (p<0.05).

CONCLUSION

Significant changes in the mean dimensions were seen as a result of disinfection by spraying; however, the dimensional changes do not seem great enough to cause critical positional distortion of teeth when fixed partial denture restorations are made.

Antibacterial and antifungal properties of polyether impression materials

The aim of this study was to evaluate the antibacterial and antifungal properties of polyether impression materials using the agar diffusion test. Three different types of polyether impression materials (P2, Penta Soft and Penta) were tested to determine their ability to inhibit the growth of Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The areas of inhibition zones were measured visually with a 0.1-mm incremental Boley gauge. In all groups, none of the samples of the P2 polyether impression material exhibited antibacterial or antifungal activity against any of the microorganisms. All Penta Soft and Penta samples exhibited antibacterial activity against E. faecalis and S. aureus, and only Penta samples exhibited antifungal effect against C. albicans, which decreased progressively as the setting time of the material increased.

Effect of Disinfection on the Dimensional Stability of Polyether Impression Materials

PURPOSE

Difficulties in sterilizing impressions have led to chemical disinfection solutions as an alternative; however, some impression materials are more sensitive to humidity. For example, polyether impression materials are more hydrophilic. This study investigated the effect of three disinfecting methods on the dimensional stability of three polyether impression materials.

MATERIALS AND METHODS

Three polyether impression materials (P2, Impregum Penta Soft, and Impregum Penta) were submitted to the following treatments: spray disinfectant (Mikrozid Liquid), immersion in 2% glutaraldehyde solution (Super-On), immersion in 0.525% sodium hypochlorite solution for 10 minutes, and a control group (not disinfected). Each group included five samples. After treatment, dimensional change was evaluated according to ISO 4823. The data were analyzed by 2-way analysis of variance at alpha= 0.05.

RESULTS

The mean percentages of linear dimensional change of materials P2, Penta Soft, and Penta were -0.040%, 0.098%, and 0.100%, respectively. The dimensional change associated with different disinfectant agents mikrozid liquid, 2% glutaraldehyde, room air (control), and 0.525% sodium hypochlorite was 0.013%, 0.024%, 0.077%, and 0.096%, respectively. The interaction between the impression materials and the disinfectant treatment was not significant. The disinfectant agents can be classified in two groups as low- and high-effected. The control group did not significantly differ from either group.

CONCLUSION

From the standpoint of dimensional change, the disinfectants tested for 10 minutes caused no significant linear dimensional change in the polyether impression materials, compared with the control group.

A Self-Disinfecting Irreversible Hydrocolloid Impression Material Mixed with Chlorhexidine Solution

Objective: To examine the antibacterial effect and several physical properties of an irreversible hydrocolloid impression material mixed with chlorhexidine solution.

Materials and Methods: The experimental irreversible hydrocolloid specimens were prepared and allocated into four groups (Group0.1 g/L, Group0.2 g/L, Group0.5 g/L, Group1.0 g/L) according to the concentrations of chlorhexidine solution used as the mixing liquid. Specimens mixed with distilled water served as a control. The antibacterial effect, three-dimensional accuracy, flowability, and setting time were tested. Statistical analysis was performed using a one-way analysis of variance and a Tukey test, which was used for multiple comparisons (α = .05).

Results: Zones of growth inhibition were observed around the test specimens, but not around the control specimens, and there were significant intergroup differences in the diameters of the inhibition zones. In the accuracy test, no significant differences (P &gt; .05) were detected among all the measurements for all groups, and the accuracy was clinically acceptable. Also, no significant differences in the flowability (P = .987) and setting time (P = .103) were detected.

Conclusion: Chlorhexidine self-disinfecting irreversible hydrocolloid impression material can exhibit varying degrees of antibacterial activity without influencing the three-dimensional accuracy, flowability, and setting time.

The dimensional stability of dental impression materials following immersion in disinfecting solutions

OBJECTIVES

This investigation examined the effect of several disinfectant systems upon the dimensional stability of a range of common dental impression materials. A new disinfection process based upon hypochlorous acid was one of those examined (Sterilox).

METHODS

Test specimens of commercially available impression materials from the following categories were investigated: alginates, addition-cured silicones, condensation-cured silicones and polyether. Three disinfection regimes were tested: sodium hypochlorite 5.25%, Perform ID and Sterilox. A custom-built automatic laser micrometer was used to measure the dimensions of sample discs of the test materials before disinfection, immediately after and then following 24h storage. Analysis of variance was employed to identify statistically significant differences within groups and across groups.

RESULTS

All the disinfection routines tested resulted in acceptable levels of dimensional stability within the category of normal use of each impression material. All the materials tested can be disinfected with 10% Sterilox without undergoing unacceptable levels of dimensional change.

SIGNIFICANCE

All the disinfection routines tested resulted in acceptable levels of dimensional stability within the category of normal use of each impression material.

Considerations for services from dental technicians in fabrication of fixed prostheses: A survey of commercial dental laboratories in Thessaloniki, Greece

STATEMENT OF PROBLEM

Effective communication and cooperation between dentists and dental technicians are essential in providing quality services. There has been a lack of information regarding dentist-dental technician communications and current methods and materials used for the fabrication of fixed partial dentures (FPDs).

PURPOSE

This cross-sectional study identified the materials and techniques used for fabrication of FPDs, as well as the status of communication between dentists and dental technicians in Thessaloniki, Greece.

MATERIAL AND METHODS

A questionnaire was developed with 7 sections pertaining to procedures and materials used for the fabrication of fixed prostheses: general questions, infection control, impressions/interocclusal records, die technique/mounting, information from final casts, prostheses design/materials, and communication/shade selection. The questionnaire was anonymous and distributed by the Association of Dental Technicians of Thessaloniki to all member laboratories (228) in the wider province of Thessaloniki, Greece. Due to the absence of normal distribution of the results, frequencies and medians were reported.

RESULTS

Ninety-six of 228 dental laboratories responded (42.1% response rate). Twenty-six percent of dental laboratories did not routinely disinfect incoming items. The dental technicians considered 30% of incoming final impressions and 20% of interocclusal registrations as inadequate. Half of the time (55%) final casts were mounted by technicians on simple hinge articulators. Only 20% of tooth preparations had adequate finish lines. The majority (70%) of fixed restorations were metal-ceramic. Fifty-seven percent of dental technicians considered the delivery time requested by dentists as insufficient.

CONCLUSION

The information provided in this study indicates areas of weakness in communication between dentists and dental technicians, along with areas where both parties should use greater care during clinical and laboratory procedures.

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Polishing of dental prostheses can cause a dangerous cycle of cross-contamination involving dentists, laboratory technicians, patients and auxiliary personnel. The aim of this study was to show the microbial contamination in the dental laboratory during the polishing procedure of complete dentures. For this purpose, 4 experiments were conducted. Experiment I - Determination of the total colony-forming units (CFU) counts contaminating complete maxillary dentures. During the polishing procedure, determination of the CFU counts transferred to the operator (Experiment II) and of the total CFU counts transferred to previously sterilized complete dentures (Experiment III). Experiment IV - The total counts of remaining CFU in the lathe spindle after Experiments II and III. Complete dentures were highly contaminated (mean = 1.4 x 10(7) CFU/mL). There was a elevated level of contamination by splatter and aerosols. There was high microbial transfer from the contaminated lathe spindle to the sterile prostheses (mean = 1.7 x 10(7) CFU/mL). The spindles were highly contaminated after polishing procedures (mean = 3.5 x 10(8) CFU/mL). The polishing of dental prostheses is a possible source of transmission of communicable diseases in the laboratory and requires improved techniques for infection control.

Calcium hypochlorite as a disinfecting additive for dental stone

STATEMENT OF PROBLEM

Dental casts come into direct contact with impression materials and other items that are contaminated by saliva and blood from a patient's mouth, leaving the casts susceptible to cross-contamination. Topical methods of disinfecting casts are difficult to control, while immersion methods are potentially destructive. Thus, an additional method to control cross-contamination between patients and laboratory personnel is needed.

PURPOSE

This study was undertaken in an attempt to develop a dental stone with disinfecting properties and adequate compressive and tensile strengths.

MATERIAL AND METHODS

Calcium hypochlorite [Ca(OCl)(2)] in aqueous solution in concentrations from 0 to 1.5% was tested as a disinfecting additive to type V dental stone. The compressive and tensile strength properties of the modified stone were measured (MPa) using a universal testing machine at a consistency similar to unmodified stone. Strength data were analyzed by 1-way ANOVA and post hoc Tukey-Kramer procedure (alpha < or =.05). To measure the disinfecting ability, the effect on Bacillis subtilis bacteriophage phi29 was tested in triplicate to find the minimum concentration at which no phage was detected. Additionally, 3 impressions were disinfected with CaviCide, and 3 impressions rinsed in water served as controls.

RESULTS

In general, the effect of adding the disinfectant to the stone was a decrease in strength. Exceptions were the dry compressive strength, for which there was a significant increase in strength (P=.048) at 0.5%, and the wet compressive and wet tensile strength, which showed no significant difference between the 1.5% and the control. When Ca(OCl)(2) was added at the concentration 0.5% (2765 ppm available chlorine), the gypsum had acceptable mechanical properties; dry compressive strength was 78.86 +/- 4.12 MPa, and dry tensile strength was 10.64 +/- 1.27 MPa, compared to control values of 67.85 +/- 6.28 and 13.41 +/- 1.24 MPa, respectively. At concentrations of 0.3% and higher (36 1650 ppm of available chlorine), calcium hypochlorite was able to completely inactivate phi29.

CONCLUSION

It is possible to prepare a type V dental stone that contains a disinfectant, has adequate mechanical properties, and will reduce numbers of residual microorganisms. For example, stone mixed with water containing 0.5% Ca(OCl)(2) meets these criteria.