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.
METHODS: 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.
CONCLUSIONS: 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.

OBJECTIVE: Ultrasonic scaling is extensively applied as part of the initial therapy for periodontal diseases, which has been restricted since the outbreak of the COVID-19 pandemic due to droplets and aerosols generated by ultrasonic devices. An extraoral scavenging device (EOS) was designed for diminishing droplets and aerosols in dental clinics. The objective of this study is to evaluate the effect of EOS on eliminating droplets and aerosols during ultrasonic supragingival scaling.
METHODS: This single-blinded, randomised controlled clinical trial enrolled 45 patients with generalised periodontitis (stage I or II, grade A or B) or plaque-induced gingivitis. The patients were randomly allocated and received ultrasonic supragingival scaling under three different intervention measures: only saliva ejector (SE), SE plus EOS and SE plus high-volume evacuation (HVE). The natural sedimentation method was applied to sample droplets and aerosols before or during supragingival scaling. After aerobic culturing, colony-forming units (CFUs) were counted and analysed.
RESULTS: Compared with the level before treatment, more CFUs of samples throughout treatment could be obtained at the operator\'s chest and the patient\'s chest and the table surface when using SE alone (p < 0.05). Compared with the SE group, the SE + EOS group and the SE + HVE group obtained decreasing CFUs at the operator\'s chest and the patient\'s chest (p < 0.05), while no significant difference was determined between these two groups.
CONCLUSIONS: The EOS effectively eliminated splatter contamination from ultrasonic supragingival scaling, which was an alternative precaution for nosocomial contamination in dental clinics.

Quantitative analysis of irregular anatomical structures is crucial in oral medicine, but clinicians often typically measure only several representative indicators within the structure as references. Deep learning semantic segmentation offers the potential for entire quantitative analysis. However, challenges persist, including segmentation difficulties due to unclear boundaries and acquiring measurement landmarks for clinical needs in entire quantitative analysis. Taking the palatal alveolar bone as an example, we proposed an artificial intelligence measurement tool for the entire quantitative analysis of irregular dental structures. To expand the applicability, we have included lightweight networks with fewer parameters and lower computational demands. Our approach finally used the lightweight model LU-Net, addressing segmentation challenges caused by unclear boundaries through a compensation module. Additional enamel segmentation was conducted to establish a measurement coordinate system. Ultimately, we presented the entire quantitative information within the structure in a manner that meets clinical needs. The tool achieved excellent segmentation results, manifested by high Dice coefficients (0.934 and 0.949), intersection over union (0.888 and 0.907), and area under the curve (0.943 and 0.949) for palatal alveolar bone and enamel in the test set. In subsequent measurements, the tool visualizes the quantitative information within the target structure by scatter plots. When comparing the measurements against representative indicators, the tool\'s measurement results show no statistically significant difference from the ground truth, with small mean absolute error, root mean squared error, and errors interval. Bland-Altman plots and intraclass correlation coefficients indicate the satisfactory agreement compared with manual measurements. We proposed a novel intelligent approach to address the entire quantitative analysis of irregular image structures in the clinical setting. This contributes to enabling clinicians to swiftly and comprehensively grasp structural features, facilitating the design of more personalized treatment plans for different patients, enhancing clinical efficiency and treatment success rates in turn.

OBJECTIVE: 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.
CONCLUSIONS: 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.

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.

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.
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.
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.
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.

The outbreak of corona virus disease (COVID-19) has raised concerns among dentists to develop strategies to prevent infection of dental equipment, materials, and patients during an epidemic period. Strategies following the National Laws and Standards of China and local standards of several provinces for controlling cross-infection and instituting protective measures for medical staff in dental clinics during an epidemic period are discussed. A proposal is put forth for dental clinics that will face similar situations in the future. Further research is warranted to address potential problems that will be encountered under such dire circumstances.
新型冠状病毒肺炎爆发对口腔医疗机构管理和临床诊疗中的传染病防护提出了新课题。本文结合我国传染病防治法、国家卫生健康委员会颁发的相关规范标准，参考部分省份口腔医疗质量控制中心制定的口腔门、急诊医院感染控制规范和本次新型冠状病毒肺炎疫情情况，对口腔门、急诊在疫情控制期控制交叉感染和医务人员防护等方面进行了探讨，希望为疫情发生时口腔医疗机构的应对和相关的临床研究提供参考。.

Splatter, droplet and aerosol, which potentially cause disease via contact and droplets transmission, may be produced during dental treatments. Through the risk model analysis of airborne diseases, it is clarified that the key points of preventing aerosol transmission are infection source management, increasing ventilation, reducing exposure time and correct use of protective masks. In order to reduce the aerosol pollution, it is necessary to strengthen the management of water and air piping systems and the control of splashing. Air and surface disinfection and enhanced personnel protection may reduce the risk. Based on the analysis of infection chain, this article elaborates the role of standard and additional precautions for cutting off the disease transmission chain. Systematic, comprehensive and evidence-based prevention and control measures should become our concerns.
口腔喷溅操作产生喷溅物、飞沫与气溶胶，当感染因子存在时，主要通过接触和飞沫传播。本文通过空气传播疾病风险模型分析，阐明预防气溶胶传播的重点为感染源管理、加大通风、减少暴露时间和正确使用防护口罩。通过对气溶胶产生和污染的分析，提出应加强水气路管理和喷溅行为控制，进行有效的空气和物表消毒、加强人员防护。基于感染链分析，阐述标准预防和附加预防措施在切断传染性疾病传播中的作用，提出口腔诊疗的感染防控需体现系统性、全面性和循证性。.

Background: Dental anxiety is a common reason for avoiding dental visits and is associated with poor dental status. The short version of Dental Anxiety Inventory (SDAxI) is an easy-to-use, multi-faceted questionnaire for assessing the level of trait dental anxiety. However, there was no neurophysiological data indicating if its score associates with the state anxiety when an individual is under real/mock dental environment. We hypothesized that there exists such an association. Materials and Methods: Twenty systemic healthy adults with dental attendance experience and self-claimed free of dental phobia were recruited in this cross-sectional study, with their dental anxiety level assessed by SDAxI. Functional magnetic resonance imaging recorded their brain signals in response to audiovisual footages resembling dental scaler or turbine in action. After the brain imaging, they gave fear ratings to the footages in visual analog scale (VAS). Results: Participants\' SDAxI scores positively correlated with their responses in the insular cortex (r2 = 0.388-0.445, P < 0.005). Their SDAxI scores also positively correlated with their fear ratings of the footages (r 2 = 0.415-0.555, P < 0.005). Discussion: Our findings indicated a possible neurobiological relevance of SDAxI, and reinforced its neurobiological validity in assessing dental anxiety level of dental attenders.

BACKGROUND: The contaminated output water from dental unit waterlines (DUWLs) is a potential risk to both patients and dental personnel who are frequently exposed to this water or aerosols.
OBJECTIVE: The purpose was to evaluate the contamination level and prevalence of bacteria in the output water of DUWLs, and to identify key factors to provide technical support for formulating relevant policies.
METHODS: We developed a special sampling connector designed for collecting dental handpiece output water and a measurement device to assess retraction of a dental chair unit (DCU). Output water from dental handpieces and air/water syringes were collected as representative of DUWLs. Water samples were tested with reference to China\'s national standard.
RESULTS: From 2012 to 2017, 318 DCUs were randomly selected from 64 hospitals in Tianjin, China. Of these DCUs, 78.93% had no disinfection to prevent DUWL contamination. Three-hundred and forty-three (56.14%) samples complied with the guidelines on DUWL output water. The highest concentration of bacteria was 1.8 × 106  colony-forming units (CFUs)/mL. The three key factors of influence were as follows: daily or weekly disinfection of DUWLs; water supply source being hospital self-made purified water or purchased purified bottled water; and DCU with a valid anti-retraction valve. Potential infectious agents, including Bacillus cereus, Burkholderia cepacia and Pseudomonas aeruginosa, were isolated.
CONCLUSIONS: There was a high rate of contamination in DUWLs. This highlights the need to develop national standards. There is a need to disinfect the DUWLs periodically and use a cleaner source of water; more attention should be paid to the efficacy of DCU anti-retraction valves.