Distribution of nontuberculous mycobacteria in dental unit waterlines: A potential health hazard in the dental office.

BACKGROUND: It is essential to control the microbiology of dental unit water lines (DUWs) to prevent the spread of nontuberculous mycobacteria (NTM) and associated oral diseases. Therefore, the objective of this study was to quantify the presence of NTM in the water of 112 DUWs from dental centers and 57 DUWs from individual dental offices in Tehran, Iran. METHODS: A total of 169 water samples were collected from DUWs. After filtration through a 0.45 µm membrane, the samples were decontaminated with 0.005 % cetylpyridinium chloride and then cultured on two Lowenstein-Jensen media, incubated at 25 °C and 37 °C for 8 weeks. Positive cultures for mycobacteria were analyzed using phenotypic tests, and the NTM species were identified through 16S rDNA, rpoB, and hsp65 genes analysis. Drug resistance was also assessed. RESULTS: Of the total isolates, 38 (34.5 %) were classified as slow-growing mycobacteria (SGM), while 72 (65.5 %) were categorized as rapid-growing mycobacteria (RGM). NTM isolates were identified using molecular tests, including M. chelonae, M. abscessus, M. lentiflavum, M. mucogenicum, M. fortuitum, M. kansasii, M. simiae, M. gordonae, M. conceptionense, M. phocaicum, M. porcinum, and M. aurum. The NTM counts ranged from 50 to >500 CFU/500 mL across these 188 samples, with a median of 350 CFU/500 mL. Additionally, we reported two cases of intraoral infection caused by M. abscessus and M. chelonae, where the source of infection was traced to NTM-contaminated DUWs. CONCLUSIONS: The study found that most DUWs contained water contaminated with NTM, posing a potential health risk to humans. This research underscores the necessity of stringent quality control and certification of DUW water, with particular emphasis on ensuring the absence of NTM.

Study on the disinfection effect of chlorine dioxide disinfectant (ClO2) on dental unit waterlines and its in vitro safety evaluation.

BACKGROUND: Ensuring the safety of dental unit waterlines (DUWLs) has become a pivotal issue in dental care practices, focusing on the health implications for both patients and healthcare providers. The inherent structure and usage conditions of DUWLs contribute to the risk of biofilm formation and bacterial growth, highlighting the need for effective disinfection solutions.The quest for a disinfection method that is both safe for clinical use and effective against pathogens such as Staphylococcus aureus and Escherichia coli in DUWLs underscores the urgency of this research. MATERIALS: Chlorine dioxide disinfectants at concentrations of 5, 20, and 80 mg/L were used to treat biofilms of S. aureus and E. coli cultured in DUWLs. The disinfection effectiveness was assessed through bacterial counts and culturing. Simultaneously, human skin fibroblast cells were treated with the disinfectant to observe changes in cell morphology and cytotoxicity. Additionally, the study included corrosion tests on various metals (carbon steel, brass, stainless steel, aluminum, etc.). RESULTS: Experimental results showed that chlorine dioxide disinfectants at concentrations of 20 mg/L and 80 mg/L significantly reduced the bacterial count of S. aureus and E. coli, indicating effective disinfection. In terms of cytotoxicity, higher concentrations were more harmful to cellular safety, but even at 80 mg/L, the cytotoxicity of chlorine dioxide remained within controllable limits. Corrosion tests revealed that chlorine dioxide disinfectants had a certain corrosive effect on carbon steel and brass, and the degree of corrosion increased with the concentration of the disinfectant. CONCLUSION: After thorough research, we recommend using chlorine dioxide disinfectant at a concentration of 20 mg/L for significantly reducing bacterial biofilms in dental unit waterlines (DUWLs). This concentration also ensures satisfactory cell safety and metal corrosion resistance.

Bacterial biofilm prevalence in dental unit waterlines: a systematic review and meta-analysis.

BACKGROUNDS: Numerous studies have shown that dental unit water lines (DUWLs) are often contaminated by a wide range of micro-organisms (bacteria, fungi, protozoa) and various prevalence have been reported for it in previous studies. Therefore, this review study aims to describe the prevalence of bacterial biofilm contamination of DUWLs. METHODS: This is a systematic review and meta-analysis in which the related keywords in different international databases, including Medline (via PubMed) and Scopus were searched. The retrieved studies were screened and the required data were extracted from the included studies. Three standard methods including American Dental Association (ADA), The Center for Disease Control and Prevention (CDC) and contaminated > 100 CFU/ml(C-100) standards were used to assess the bacterial biofilm contamination of DUWLs. All studies that calculated the prevalence of bacterial biofilm contamination of DUWLs, and English full-text studies were included in the meta-analysis. Studies that did not have relevant data or used unusual laboratory methods were excluded. Methodological risk of bias was assessed by a related checklist and finally, the data were pooled by fixed or random-effect models. RESULTS: Seven hundred and thirty-six studies were identified and screened and 26 related studies were included in the meta-analysis. The oldest included study was published in 1976 and the most recent study was published in 2020. According to the ADA, CDC and C-100 standards, the prevalence of bacterial contamination was estimated to be 85.0% (95% confidence interval (CI): 66.0-94.0%), 77.0% (95%CI: 66.0-85.0%) and 69.0% (95%CI: 67.0-71.0%), respectively. The prevalence of Legionella Pneumophila and Pseudomonas Aeruginosa in DUWLs was estimated to be 12.0% (95%CI: 10.0-14.0%) and 8.0% (95%CI: 2.0-24.0%), respectively. CONCLUSION: The results of this review study suggested a high prevalence of bacterial biofilm in DUWLs; therefore, the use of appropriate disinfecting protocol is recommended to reduce the prevalence of contamination and reduce the probable cross-infection.

Dental unit waterline testing practices: an 11-Year retrospective study.

OBJECTIVES: This retrospective study examined the dental unit waterline (DUWL) testing practices of Saskatchewan dental clinics over a period of 11 years, with an emphasis on their responses after identification of high microbial levels. MATERIALS AND METHODS: Dental clinics (n = 137) aseptically collected samples of output water from their air/water syringes, handpieces, and ultrasonic scaler lines using Sigma-Aldrich® waterline test kits and delivered them to a quality assurance laboratory. Tests were incubated for seven days at room temperature, and those with heterotrophic plate counts > 500 CFU/mL were reported as failures. Statistical analyses were performed on a database containing 4,093 test results. RESULTS: Participating clinics submitted an average of 11 DUWL tests per year. Overall, 21% of tests failed, and a moderate positive association (rs=.52, p < 0.001) was found between clinics' DUWL testing frequency and failure rate. Only 7% of failed DUWL tests were followed up by collection of a subsequent test within two weeks, of which 47% still exceeded the 500 CFU/mL threshold. CONCLUSIONS: Our findings demonstrate an association between DUWL testing frequency and detection of unacceptable microbial levels, along with infrequent retesting and often-inadequate intervention after a failed test. This suggests the need for further efforts at the regulatory and educational levels to maintain adequate water quality during dental treatment. CLINICAL RELEVANCE: Procedural water can become contaminated in DUWLs and endanger patients. Regular DUWL monitoring and evidence-based interventions to treat contaminated systems are necessary to safeguard patient health.

Comparative evaluation of effect of sodium hypochlorite and chlorhexidine in dental unit waterline on aerosolized bacteria generated during dental treatment.

BACKGROUND: In dentistry, nosocomial infection poses a great challenge to clinicians. The microbial contamination of water in dental unit waterlines (DUWLs) is ubiquitous. Such infected DUWLs can transmit oral microbes in the form of aerosols. Previous studies have suggested treating DUWLs with various disinfectants to reduce cross-contamination. The literature lacks a comparative evaluation of the effect of the use of 0.2% chlorhexidine (CHX) and 0.1% sodium hypochlorite (NaOCl) in DUWLs on aerosolized bacteria generated during dental procedures. OBJECTIVE: To compare the effect of NaOCl and CHX in DUWLs on aerosolized bacteria generated during restorative and endodontic procedures. MATERIALS AND METHODS: A total of 132 patients were equally divided into three groups (n = 44 in each group) according to the content of DUWL as follows. Group I-0.1% NaOCl Group II-0.2% CHX Group III-distilled water (Positive control) One-way ANOVA was performed and the Kruskal-Wallis test was used for intergroup comparison. RESULTS: For the restorative procedure, inter-group comparison of mean colony-forming units (CFU) scores showed a statistically significant difference between the groups (p - .001) with the score of group 3 higher than group 2 followed by group 1. For the endodontics, an inter-group comparison of CFU scores showed a statistically significant difference between the groups (p - .003) with the mean score in group 1 being the lowest and group 3 being the highest. CONCLUSION: The addition of NaOCl or CHX in DUWLs shows an effective reduction in aerosolized bacteria compared to distilled water.

Protocol with non-toxic chemicals to control biofilm in dental unit waterlines: physical, chemical, mechanical and biological perspective.

Biosafety in dentistry aims to combat cross-contamination and biofilm in dental unit waterlines. The aim was to investigate from a physical, chemical, mechanical and biological perspective, a protocol for using chemical products (citric acid, sodium bicarbonate and sodium chloride) to improve and maintain water quality in dental unit waterlines. Change in microhardness and corrosion tendency were observed in stainless steel samples. On the polyurethane surfaces, there were changes in color, microhardness and roughness. Anti-biofilm evaluations revealed a significant reduction in the biofilm biomass, metabolic activity and residual biofilm. These findings suggest that the protocol analyzed in this study showed an innovative potential against biofilm in dental unit waterlines, preserving the physical, chemical and mechanical properties of the materials.

[Can dental equipment interfere with correct functioning of an ICD?] / Beïnvloedt tandheelkundige apparatuur de werking van een ICD?

An implantable cardioverter defibrillator (ICD) is often placed in patients at high risk of ventricular tachycardia and ventricular fibrillation. An ICD is potentially sensitive to electromagnetic interference (EMI) from dental equipment. Between 2000 to 2020, this was investigated in 7 in vitro studies and 4 in vivo studies. Most dental equipment appears to be safe for routine use in patients with an ICD. However, caution seems appropriate with regard to the use of piezoelectic and magnetostrictive scalers as some can cause EMI up to a distance of 20 to 45 centimeter. Use of an electrotome appears to be contraindicated in ICD wearers.

Anti biofilm effect of low concentration chlorine containing disinfectant assisted by multi enzyme detergent in dental unit waterlines.

The highly structured biofilms on the surface of internal tubing are regarded as the most important source of water pollution in the dental unit waterline (DUWL). Herein, the study aimed to evaluate the anti-biofilm effect of combined application of chlorine-containing disinfectant with multi-enzyme detergent in the dental unit waterline. Six dental units were included and randomly divided into two groups - Group A was treated with chlorine-containing disinfectant and multi-enzyme detergent; Group B was treated only with chlorine-containing disinfectant as control. All groups were treated once a day for four weeks. The anti-biofilm effect was evaluated by heterotrophic plate counts in output water, structure of biofilms, and fluorescence density of biofilms before and after treatment. Abundant opportunistic bacteria forming dense biofilms were observed before treatment. After one week, scanning electron microscopy showed the extracellular polymeric substance of biofilms in Group A was partially destroyed. The biofilms of Group A were completely removed in the third week, while the biofilms of Group B were still present. The combined application of chlorine-containing disinfectant and multi-enzyme detergent achieved a satisfactory effect on biofilms removal, demonstrating this strategy may play a significant role in reducing contamination in the dental clinic.

Evaluation of the antimicrobial effect of silver ion tubing on dental unit waterlines.

PURPOSE: To assess the antimicrobial effects of silver ion tubing (ST) on dental unit waterlines (DUWLs) and their sustainability over time. METHODS: Six dental chair units (DCUs) equipped with ST and four with common tubing (CT) were included in the study. Repeated flushing with phosphate-buffered saline (PBS) was conducted to dislodge biofilms. Then, genetic analysis of the PBS was performed. The tubing was also detached and scanned under a scanning electron microscope (SEM) to observe the adherent biofilm on the lumen walls. RESULTS: Low bacterial levels were noted in both the CT and ST groups, but biofilm attachment was only observed in the CT group. CLINICAL SIGNIFICANCE: Silver ion tubing exhibited high antibacterial activity by reducing the colonization of pathogens in the dental unit water inhibiting biofilm formation, and showing promise as an efficient infection control method for dental unit waterlines.

Electromagnetic interference effect of dental equipment on cardiac implantable electrical devices: A systematic review.

BACKGROUND: The electromagnet interference (EMI) effect resulting from using dental equipment near cardiovascular implantable electronic devices (CIEDs) is controversial based on in vitro and in vivo studies. We aimed to summarize the available evidence to investigate the safety of using dental equipment on patients with CIEDs. METHODS: An electronic search was performed in PubMed, Embase, MEDLINE Ovid, and the Cochrane Library for relevant studies published between January 2000 and May 2020. The search strategy centered on terms related to dental devices and CIEDs. Two independent reviewers determined the final inclusion of the studies in the systematic review. The EMI effect was summarized based on different dental instruments detected in in vitro or in vivo studies. RESULTS: The primary search identified 84 articles, and 18 studies were finally included in this systematic review after exclusions. Most in vitro studies (n = 12) reported background noise or severe EMI affecting CIED function at a close distance from the lead tip or at a high sensitivity setting of CIEDs. In in vivo studies (n = 6), EMI that altered CIED function was not detected at clinical distance and sensitivity settings. The summary, based on electronic apex locators, ultrasonic devices, and electric pulp testers, demonstrated the compatibility of these common dental devices with CIEDs. CONCLUSIONS: This systematic review indicates that most dental instruments can be used safely in routine dental practice. The EMI effect of dental equipment depends on the exposure distance and lead-related parameters of the CIEDs.

Heterogeneity in the efficacy of dental chemical disinfectants on water-derived biofilms in vitro.

Conditions in dental unit waterlines are favourable for biofilm growth and contamination of dental unit water. The aim of this study was to assess the effect of several chemical disinfectants on bacteria in a biofilm model. Water-derived biofilms were grown in a static biofilm model (Amsterdam Active Attachment model), using two growth media. Biofilms were challenged with Alpron/Bilpron, Anoxyl, Citrisil, Dentosept, Green & Clean, ICX and Oxygenal in shock dose and maintenance doses. The concentration and the composition of the chemical disinfectants influenced the number of culturable bacteria in the biofilms. The application of a single shock dose followed by a low dose of the same chemical disinfectants resulted in the greatest suppression of viable bacteria in the biofilms. Exposure to Citrisil and ICX consistently resulted in failure to control the biofilms, while Alpron/Bilpron had a substantial and relevant effect on the number of bacteria in the biofilms.

Importing Automated Management System to Improve the Process Efficiency of Dental Laboratories.

Dental laboratories require manpower resources for manufacturing prostheses and inventory management. In this paper, we developed an automated inventory management system for dental laboratories to improve the production efficiency. A sensing system was developed based on the framework of Internet of things to collect the information of cobalt-chromium disks both in the storage room and manufacturing area, and an expert system was developed to automatically conduct inventory management based on the established rules. The proposed system can reduce the time of recording data and also assist the manager in configuring and managing material orders. The experimental results showed that a large amount of working time is reduced, resulting in the benefits of saving money and improving efficiency in dental manufacturing.

Discomfort/pain due to periodontal and peri-implant probing with/without platform switching.

OBJECTIVE: To compare discomfort/pain following periodontal probing around teeth and peri-implant probing around implants with or without platform switching. METHODS: Two dentists recruited and examined 65 patients, each of them exhibiting a dental implant with a contralateral tooth. Only two types of implants were included: one with and one without platform switching. Periodontal and peri-implant probing depths (PPD) and probing attachment level (PAL) were assessed. Whether implant or tooth was measured first was randomly assigned. Immediately after probing, patients scored discomfort/pain using a visual analogue scale (VAS). The emergence profiles of implant crowns were assessed as angles between interproximal surfaces on radiographs. RESULTS: Sixty-five patients (age 69; 63/76 years [median; lower/upper quartile]; 38 females, 11 smokers) were examined. With the exception of mean PPD and PAL (p < .05) clinical parameters (PPD, PAL, bleeding on probing, suppuration) were well balanced between implants and teeth. Peri-implant probing (VAS: 10; 0.75/16.25) caused significantly (p < .001) more discomfort/pain than periodontal probing (4; 0/10). Logistic regression analysis identified a larger difference between discomfort/pain for peri-implant and periodontal probing in the maxilla than the mandible (p = .003). Comparing discomfort/pain between implants maxilla (p = .006) and emergence profile (p = .015) were associated with discomfort/pain. Type of implant (with/without platform switching) had no significant effect on discomfort/pain. CONCLUSIONS: Peri-implant probing caused significantly more discomfort/pain than periodontal probing. Implant design with/without platform switching failed to have a significant effect on discomfort/pain.

Colonization by Pseudomonas aeruginosa of dental unit waterlines and its relationship with other bacteria: suggestions for microbiological monitoring.

Pseudomonas aeruginosa is an environmental bacterium, ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines (DUWLs). We investigated the prevalence of P. aeruginosa in DUWLs from private dental settings. We also analyzed the relationship between P. aeruginosa contamination and the presence of Legionella spp. and total viable count (TVC) in order to suggest a simple and inexpensive protocol to test the quality of water from DUWLs. We detected and quantified P. aeruginosa both by culture and by a PMA (propidium monoazide)-qPCR method. Overall, we detected P. aeruginosa in 17 samples using the PMA-qPCR and in 11 samples using the culture. All culture-positive samples were positive with the PMA-qPCR too, with an agreement between the two methods of 93% and a Cohen's kappa coefficient of κ = 0.747 (good concordance). Comparing results with results of our previous study, we noted that (a) P. aeruginosa was isolated only from DUWLs with high TVC and (b) five out of six Legionella-positive samples were negative for Pseudomonas spp. Our final suggestion is that the cleanliness of DUWLs should be assessed by TVC because it is a good indicator of the presence of pathogens such as Legionella spp. and P. aeruginosa.

Radiation dose measurements in a dental orthopantogram unit using indigenously developed optically stimulated luminescence dosimeters.

Dental orthopantogram (OPG)/cone beam computed tomography (CBCT) scanners are gaining popularity due to their 3D imaging with multiplanar view that provides clinical benefits over conventional dental radiography systems. Dental OPG/CBCT provides optimal visualization of adjacent overlaying anatomical structures that will be superpositioned in any single projection. The characteristics of indigenously developed optically stimulated luminescence dosimeters, namely, aluminium oxide doped with carbon (Al2 O3 :C), lithium magnesium phosphate doped with terbium and boron (LiMgPO4 :Tb,B) and lithium calcium aluminium fluoride doped with europium and yttrium (LiCaAlF6 :Eu,Y) were evaluated for their use in dental dosimetry. The dose-response of these dosimeters was studied at X-ray energies 60 kV, 70 kV and 81 kV. Radiation doses were also measured using Gafchromic film for comparison. Radiation dose was measured at eight different locations of a polymethyl methacrylate (PMMA) head phantom including eyes. The optically stimulated luminescence (OSL) sensitivity of LiMgPO4 :Tb,B is about 1.5 times and LiCaAlF6 :Eu, is about 20 times higher than the sensitivity of Al2 O3 :C. It was found that measured radiation doses by the three optically stimulated luminescence dosimeters (OSLDs) and Gafchromic film in the occipital region (back side) of a PMMA phantom, were consistent but variations in dose at other locations were significantly higher. The three OSLDs used in this study were found to be suitable for radiation dose measurement in dental units.

Efficacy of acoustic waves in preventing Streptococcus mutans adhesion on dental unit water line.

BACKGROUND: The quality and health safety of water used for refrigeration and flushing of the handpieces, water-syringes and other components of dental units is of considerable importance. Water crosses these devices by a system of intersected small plastic tubes (about 2 mm of diameter), named dental unit water lines (DUWLs). DUWLs may be heavily colonized by many bacterial species in a planktonic phase, adherent or in biofilm lifestyle, resulting in a potential risk of infection, not only for all professionals who routinely use these devices, but also for occasional-patients, especially immunocompromised patients. Contamination of DUWLs can be prevented or reduced with the use of disinfectants, but the eradication of microorganisms, especially which those are adherent or living in biofilm lifestyle on the inner surfaces of DUWLs is challenging and often, the normal methods of water disinfection are not effective. Moreover, disinfectants routinely used to disinfect DUWLs may alter the bond strength of the dentine bonding agent used for restorative practice in dentistry. STUDY DESIGN: To identify an innovative and alternative strategy, able to prevent bacterial adhesion to DUWL surfaces through a physical approach, which is more effective in overcoming the problem of DUWL contamination and the risk of infection compared to the standard methods already in use. In this pilot study we tested a member of the oral streptococci family, that is not a component of the biofilm detected on the walls of DUWL, but is frequently detected in water samples from DUWL, due to human fluid retraction during dental therapy. Namely, the pathogenic bacterial species Streptococcus mutans. METHODS: We employ elastic acoustic waves at high-energy in preventing S. mutans adhesion to the inner walls of an experimental water circuit reproducing a DUWLs. To stress the capability of acoustic waves to interfere with bacterial adhesion also in extreme conditions, a high S. mutans contamination load was adopted. RESULTS: We observe a significant decrease of adherent bacteria exposed to acoustic waves treatment respect to control. CONCLUSION: This study demonstrates the effectiveness of acoustic waves in counteracting the adhesion of S. mutans to the inner walls of an experimental water circuit reproducing a DUWL, opening up new prospects for future practical applications. The interesting results, so far obtained, require an in-depth analysis of the methods regarding both the various bacterial species involved and the infective charges to be used.

Replication of Ancient Egyptian Oral Surgical Procedures Using Stone and Bronze Hand Drills.

For over a hundred years researchers have disputed whether ancient Egyptians performed the oral surgical procedure of drilling holes in jaws, presumably in an attempt to relieve pressure and pain due to periapical infections. To date (although it has been indirectly suggested) there have been no published attempts to reproduce the disputed holes identified in the Egyptian mandibles with tools fabricated from stone and bronze, the materials that were available to ancient Egyptian artisans. This paper presents an abbreviated assessment of oral surgery in ancient Egypt regarding these procedures, with an attempt to reproduce these procedures on fresh pig and embalmed cadaver jaws as proxies for vital human bone, using hand drills that were fabricated of bronze and chet.The experiment confirms that the procedure could be effectively performed with basic hand tools. In comparison to fresh pig mandible the embalming process hardens cadaver bone. Redesign of drill handles would increase efficiency.

Colonization of Legionella spp. In dental unit waterlines.

Legionella spp. are ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines. Surveys have shown that the percentage of samples taken at different dental sites that were positive for Legionella spp. were highly variable and ranged from 0% to 100%. Cultivation is the principal approach to evaluating bacterial contamination employed in the past, but applying this approach to testing for Legionella spp. may result in false-negative data or underestimated bacterial counts. PCR and direct fluorescent counts can detect viable non-cultivable bacteria, which are not counted by plating procedures. Legionella spp., commonly form such viable non-culturable cells and it is likely that they contribute to the difference between plate count results and those of PCR and fluorescent-antibody detection. However, studies have shown that Legionella is present in the municipal water source in spite of the current filtration and chlorination procedures. Once Legionella reaches the building water system, it settles down into a biofilm layer of stagnant water. By means of this layer, Legionella can protect itself from antimicrobial agents and then multiply. Dental unit waterlines may be contaminated with opportunistic bacteria. The water quality in the dental units should be controlled to eliminate opportunistic pathogens and to provide water for dental treatment that meets public health standards for potable water.

Ergonomic interventions for preventing musculoskeletal disorders in dental care practitioners.

BACKGROUND: Dentistry is a profession with a high prevalence of work-related musculoskeletal disorders (WMSD) among practitioners, with symptoms often starting as early in the career as the student phase. Ergonomic interventions in physical, cognitive, and organisational domains have been suggested to prevent their occurrence, but evidence of their effects remains unclear. OBJECTIVES: To assess the effect of ergonomic interventions for the prevention of work-related musculoskeletal disorders among dental care practitioners. SEARCH METHODS: We searched CENTRAL, MEDLINE PubMed, Embase, PsycINFO ProQuest, NIOSHTIC, NIOSHTIC-2, HSELINE, CISDOC (OSH-UPDATE), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP) Search Portal to August 2018, without language or date restrictions. SELECTION CRITERIA: We included randomised controlled trials (RCTs), quasi-RCTs, and cluster RCTs, in which participants were adults, aged 18 and older, who were engaged in the practice of dentistry. At least 75% of them had to be free from musculoskeletal pain at baseline. We only included studies that measured at least one of our primary outcomes; i.e. physician diagnosed WMSD, self-reported pain, or work functioning. DATA COLLECTION AND ANALYSIS: Three authors independently screened and selected 20 potentially eligible references from 946 relevant references identified from the search results. Based on the full-text screening, we included two studies, excluded 16 studies, and two are awaiting classification. Four review authors independently extracted data, and two authors assessed the risk of bias. We calculated the mean difference (MD) with 95% confidence intervals (CI) for continuous outcomes and risk ratios (RR) with 95% confidence intervals for dichotomous outcomes. We assessed the quality of the evidence for each outcome using the GRADE approach. MAIN RESULTS: We included two RCTs (212 participants), one of which was a cluster-randomised trial. Adjusting for the design effect from clustering, reduced the total sample size to 210. Both studies were carried out in dental clinics and assessed ergonomic interventions in the physical domain, one by evaluating a multi-faceted ergonomic intervention, which consisted of imparting knowledge and training about ergonomics, work station modification, training and surveying ergonomics at the work station, and a regular exercise program; the other by studying the effectiveness of two different types of instrument used for scaling in preventing WMSDs. We were unable to combine the results from the two studies because of the diversity of interventions and outcomes.Physical ergonomic interventions. Based on one study, there is very low-quality evidence that a multi-faceted intervention has no clear effect on dentists' risk of WMSD in the thighs (RR 0.57, 95% CI 0.23 to 1.42; 102 participants), or feet (RR 0.64, 95% CI 0.29 to 1.41; 102 participants) when compared to no intervention over a six-month period. Based on one study, there is low-quality evidence of no clear difference in elbow pain (MD -0.14, 95% CI -0.39 to 0.11; 110 participants), or shoulder pain (MD -0.32, 95% CI -0.75 to 0.11; 110 participants) in participants who used light weight curettes with wider handles or heavier curettes with narrow handles for scaling over a 16-week period.Cognitive ergonomic interventions. We found no studies evaluating the effectiveness of cognitive ergonomic interventions.Organisational ergonomic interventions. We found no studies evaluating the effectiveness of organisational ergonomic interventions. AUTHORS' CONCLUSIONS: There is very low-quality evidence from one study showing that a multi-faceted intervention has no clear effect on dentists' risk of WMSD in the thighs or feet when compared to no intervention over a six-month period. This was a poorly conducted study with several shortcomings and errors in statistical analysis of data. There is low-quality evidence from one study showing no clear difference in elbow pain or shoulder pain in participants using light weight, wider handled curettes or heavier and narrow handled curettes for scaling over a 16-week period.We did not find any studies evaluating the effectiveness of cognitive ergonomic interventions or organisational ergonomic interventions.Our ability to draw definitive conclusions is restricted by the paucity of suitable studies available to us, and the high risk of bias of the studies that are available. This review highlights the need for well-designed, conducted, and reported RCTs, with long-term follow-up that assess prevention strategies for WMSDs among dental care practitioners.

In-vivo compatibility between pacemakers and dental equipment.

In-vitro studies suggest that electromagnetic interference can occur under specific conditions involving proximity between electronic dental equipment and pacemakers. At present, in-vivo investigations to verify the effect of using electronic dental equipment in clinical conditions on patients with pacemakers are scarce. This study aimed to evaluate, in vivo, the effect of three commonly used electronic dental instruments - ultrasonic dental scaler, electric pulp tester, and electronic apex locator - on patients with different pacemaker brands and configurations. Sixty-six consecutive non-pacemaker-dependent patients were enrolled during regular electrophysiology follow-up visits. Electronic dental tools were operated while the pacemaker was interrogated, and the intracardiac electrogram and electrocardiogram were recorded. No interferences were detected in the intracardiac electrogram of any patient during the tests with dental equipment. No abnormalities in pacemaker pacing and sensing function were observed, and no differences were found with respect to the variables, pacemaker brands, pacemaker configuration, or mode of application of the dental equipment. Electromagnetic interferences affecting the surface electrocardiogram, but not the intracardiac electrogram, were found in 25 (37.9%) patients, especially while using the ultrasonic dental scaler; the intrinsic function of the pacemakers was not affected. Under real clinical conditions, none of the electronic dental instruments tested interfered with pacemaker function.