Environmental implications of dental restorative materials on the zebrafish Danio rerio: Are dental chair drainage systems an emerging environmental threat?

This study aimed to evaluate the environmental impact of dental materials: commercial composite Tetric EvoCeram®, glass ionomer Equia Forte® HT Fil, laboratory-prepared composite, alkasite Cention® Forte, amalgam Amalcap® Plus, and samples from dental chair drainage systems (DCDS). Methacrylate monomers were detected in the eluates of experimental and commercials composites, and alkasite. In DCDS samples solely mercury was found at concentrations of 0.08-1.86 µg/L. The experimental composite (48 h incubation) exhibited the highest toxicity on zebrafish Danio rerio (LC50=0.70 g/L), followed by amalgam (LC50=8.27 g/L) < Tetric EvoCeram® (LC50=10.94 g/L) < Equia Forte® HT Fil (LC50=24.84 g/L) < Cention® Forte (LC50=32.22 g/L). Exposure of zebrafish to DCDS samples resulted in decreased larval body length and increased occurrences of edema and blood accumulation. The results obtained highlight the need for additional monitoring and further research on the release of unreacted monomers and mercury from dental materials and their environmental impact.

Initial waterline contamination by Pseudomonas aeruginosa in newly installed dental chairs.

Water contamination in dental unit waterlines (DUWLs) is a potential source of healthcare-associated infection during dental care. The aim of this study was to evaluate the microbiological quality of DUWLs water from newly installed dental chairs in a French University Hospital. The microbiological quality of water from 24 new DUWLs initially disinfected by ICX Renew-prior to use of the dental units for patient treatment-was assessed for total culturable aerobic bacteria at 22°C and 36°C, Legionella sp., Pseudomonas aeruginosa, and total coliforms. Among the 24 samples analyzed, 21 were compliant with the water quality levels: 19 had no bacteria, and 2 contained only 4 and 1 CFU/mL for total culturable aerobic bacteria at 22°C and 36°C, respectively. Three samples were non-compliant due to contamination by P. aeruginosa (4, 2, and 2 CFU/100 mL). Controlling and preventing the microbiological contamination of DUWLs, especially by pathogenic bacteria, at the time of the installation of the new dental chairs are crucial to prevent healthcare-associated infection in dentistry. IMPORTANCE: Dental unit waterlines (DUWLs) of new dental chairs may be contaminated before their first clinical use, so an initial shock disinfection is crucial at the time of their installation. The microbiological analyses are crucial to control the water quality of DUWLs before their first clinical use because their disinfection does not guarantee the elimination of all bacteria.

Effective disinfecting of negative pressure pipelines of DCUs reduces the risk of cross infection in dental care.

Objectives: Microbial contamination of various accessory parts of the dental chair units (DCUs) is an essential source of cross infection, while the accessories of the crucial suction function are usually overlooked. In this study, we aim to find an effective disinfectant and a cost-effective method to remove bacterioplankton and bacterial biofilm deposited in the negative pressure suction pipelines to control cross infection during dental treatment. Methods: Double-chain quaternary ammonium salt disinfectant (Orotol Plus®), 3% hydrogen peroxide solution plus multi-enzyme cleaning agent and chlorine disinfectant are used to clean and disinfect the negative pressure pipelines of DCUs. Microbiological examinations, air condition detection, corrosion tests and gene sequencing are performed. Results: Little bacteria grow in the pipelines disinfected with double-chain quaternary ammonium salt disinfectants, destruction of biofilms in these pipelines appears, and multi-resistant bacteria cannot be detected. Minimal damage to metal sheets and fittings is caused by double-chain quaternary ammonium salt disinfectants. Conclusion: Double-chain quaternary ammonium salt disinfectant has excellent bactericidal ability and anti-biofilm effect, and it is less corrosive to the fittings of the pipelines. Thus, the double-chain quaternary ammonium salt disinfectant is a potential novel disinfectant for negative pressure suction pipelines of DCUs to control cross infection during dental treatment. Clinical significance: It is essential to add all these data to our dental practice to control cross infection with a broader landscape.

Analysis of dental clinic and dental chair distribution in Sichuan.

OBJECTIVES: To thoroughly understand the current dental chair equipment status of dental clinics in Sichuan Province and provide a reference for administrative departments. METHODS: Data were collected from a health administrative department and a regional social development yearbook. The number of existing dental clinics and dental chairs in Sichuan Province was investigated. RESULTS: In Sichuan Province, 7 103 dental clinics were determined to be equipped with 21 760 dental chairs. The Gini coefficients of per capita dental clinics in the province were 0.50, 0.22, and 0.06, and the Gini coefficients of per capita dental chairs were 0.68, 0.31, and 0.15; these coefficients had the same distribution as that reflected by the Lorenz curve. In consideration of geographic distribution, the Theil index for the distribution of dental clinics and dental chairs among cities and states were 0.690 7 and 0.822 3, respectively. The overall Theil index va-lues for the distribution of dental clinics and dental chairs in the province were 0.902 4 and 1.079 4, respectively. The difference in the distribution of dental clinics and dental chairs among cities and states in the province contributed 0.765 4 and 0.761 8 to the total difference, respectively. CONCLUSIONS: The allocation of oral health resources in Sichuan Pro-vince is relatively equitable in terms of population and economic distribution but uneven in geographical distribution.

Analysis of dental clinic and dental chair distribution in Sichuan / 华西口腔医学杂志

OBJECTIVES@#To thoroughly understand the current dental chair equipment status of dental clinics in Sichuan Province and provide a reference for administrative departments.@*METHODS@#Data were collected from a health administrative department and a regional social development yearbook. The number of existing dental clinics and dental chairs in Sichuan Province was investigated.@*RESULTS@#In Sichuan Province, 7 103 dental clinics were determined to be equipped with 21 760 dental chairs. The Gini coefficients of per capita dental clinics in the province were 0.50, 0.22, and 0.06, and the Gini coefficients of per capita dental chairs were 0.68, 0.31, and 0.15; these coefficients had the same distribution as that reflected by the Lorenz curve. In consideration of geographic distribution, the Theil index for the distribution of dental clinics and dental chairs among cities and states were 0.690 7 and 0.822 3, respectively. The overall Theil index va-lues for the distribution of dental clinics and dental chairs in the province were 0.902 4 and 1.079 4, respectively. The difference in the distribution of dental clinics and dental chairs among cities and states in the province contributed 0.765 4 and 0.761 8 to the total difference, respectively.@*CONCLUSIONS@#The allocation of oral health resources in Sichuan Pro-vince is relatively equitable in terms of population and economic distribution but uneven in geographical distribution.

Comparison of different methods of more effective chest compressions during cardiopulmonary resuscitation (CPR) in the dental chair.

Introduction: When performing cardiopulmonary resuscitation (CPR) on a patient who has suffered a cardiopulmonary arrest during dental treatment, few dental chairs have sufficient stability to perform effective chest compressions. We previously proposed a method of stabilizing the backrest of a dental chair using a support stool. As a result, we confirmed that the vertical displacement of the backrest could be significantly reduced. In the present study, we verified the effectiveness of the stool stabilization method using several dental chairs (flat and curved) with significantly different backrest shapes. Methods: Vertical displacement of the backrests of dental chairs was recorded. Data were obtained at three different stool positions (without a stool, under the chest at the level that participants were performing manual chest compressions, and under the shoulders). Reduction displacement ratios were calculated to evaluate the effectiveness of the stool positions. Results: The method significantly reduced the vertical displacement of the backrest for all types. When the curvature of the backrest was large, the reduction in vertical displacement was 40% when the stool was placed under the chest at the level of manual chest compressions and 65% when placed underneath the shoulder. In the case of a flat dental chair, this reduction was 90% when using a stool in either position, compared to no stool. Conclusion: When we need to perform CPR on a patient in the dental chair, placing a stool under the shoulders allows effective manual chest compression by firmly supporting the backrest of a dental chair of any shape.

A Comparison of Two Stool Positions for Stabilizing a Dental Chair During CPR.

OBJECTIVE: Most dental chairs lack sufficient stability to perform effective manual chest compression (MCC) during cardiopulmonary resuscitation (CPR). A stabilizing stool can significantly reduce backrest vertical displacement in all chair types; however, a severely curved exterior backrest may negatively impact the stool's effectiveness. This study evaluated the efficacy of 2 stool positions for stabilizing a dental chair during MCC. METHODS: Chest compressions were performed on a manikin positioned in a dental chair while vertical displacement of the chair backrest during MCC was recorded using video and measured. Vertical displacement data were captured with no stool and with a stabilizing stool in 2 different positions. Reduction ratios were calculated to evaluate the effectiveness of the 2 stool positions. RESULTS: With no stool, the backrest median (interquartile range) vertical displacement during chest compressions was 16.5 (2.5) mm as compared with 12.0 (1.5) mm for the stabilizing stool positioned under the area of MCC and 8.5 (1.0) mm under the shoulders. The stool positioned under the shoulders produced a significantly increased calculated reduction ratio of 48% (14%) compared with 27% (20%) under the area of MCC (P < .001). CONCLUSIONS: Positioning a stabilizing stool under the shoulders was more effective at reducing vertical displacement of the dental chair backrest during chest compressions than positioning the stool under the area of MCC.

Comparison of two types of disinfectants on the disinfection of the fixed end of the table suction pipe in the oral comprehensive treatment table / 口腔疾病防治

Objective@#To compare the disinfection effects of 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant applied to the threaded plastic hose at the fixed end of the saliva suction pipe of the oral comprehensive treatment table after diagnosis and treatment of patients in stomatology to provide a basis for clinical cleaning and disinfection.@* Methods @#The fixed ends of saliva suction pipes of 12 comprehensive treatment tables in the dental pulp department and maxillofacial surgery were selected as the research objects. The absorption was randomly divided into two groups and a control group: experimental group 1 with 500 mg/L chlorine disinfectants and experiment 2 group with 3% hydrogen peroxide disinfectant rinse disinfection and the control group with 0.9% sterile saline flushing pipe once a week for four weeks. Before and after washing and disinfection, samples from the inner wall of the threaded plastic hose interface were collected for bacterial culture and colony count, and colony counts within and between groups were compared before and after disinfection. Statistical analysis was conducted using SPSS 24.0 software.@*Results@#The baseline number of bacterial colonies in the first three groups was balanced, with no statistically significant difference (χ2 = 0.538, P = 0.764). The number of bacterial colonies after washing and disinfection was lower than that before washing and disinfection. The difference between 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant before and after disinfection was highly significant (Z = -4.801, P<0.001; Z = -4.429, P<0.001). There was no significant difference between the disinfection effect of 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant, but they were both better than the control group (χ2 = 18.070, P<0.001).@*Conclusion@#Disinfecting the saliva suction pipe with disinfectant between diagnosis and treatment can effectively reduce the bacterial contamination at the fixed end threaded plastic hose interface of the saliva suction pipe. The disinfection method is simple and convenient, and it is worth applying in the oral clinic.

Measuring the Level of Medical-Emergency-Related Knowledge among Senior Dental Students and Clinical Trainers.

OBJECTIVES: This study aimed to measure the level of medical-emergency-related knowledge among senior dental students and clinical trainers in Saudi Arabia. METHODS: This cross-sectional pilot survey was conducted at Taibah Dental College, Madina, Saudi Arabia between March 2017 and November 2018. Two hundred and seventy-five self-administered anonymous questionnaires on the management of common medical emergencies were distributed to all senior dental students and clinical trainers at Taibah Dental College. RESULTS: There was a serious lack of knowledge regarding the management of medical emergency scenarios among the participants. Only 54% of participants knew the correct management for some frequent and life-threating conditions such as "crushed chest pain", and only 30-35% of participants knew the correct management of deeply sedated patients with benzodiazepine overdose and crisis of hypoadrenalism. Moderate-quality knowledge (50-74% of participants responded correctly) was noted for the following conditions: sudden onset of brain stroke, psychiatric patient, unconscious patient with hypoglycemia, patient with postural hypotension, and patient with hyperventilation. Based on the scale of knowledge, there were significant differences in the level of knowledge between clinical trainers, senior dental students, and junior dental students (p ≤ 0.01). Almost all students and 90% of trainers declared the need for further training. CONCLUSIONS: The overall knowledge regarding the management of medical emergency crises in the dental chair was moderate. However, the scale of knowledge regarding the management of medical emergency crises has gradually increased with the number of years of experience. Most participants recognize the need for further training.

Efficacy of Chest Compressions Performed on Patients in Dental Chairs Versus on the Floor.

This study aimed to investigate the characteristics of chest compressions performed in dental chairs (DCs) with 2 different structural support designs and on the floor. This randomized prospective study was conducted to compare the effectiveness of chest compressions (rate and depth) using a feedback device and a manikin reporting system. The mean anterior chest wall motion measurements captured using the feedback device were significantly increased in the DCs than on the floor, whereas the percentage of net chest compression depths ≥5 cm as measured using the manikin reporting system were significantly decreased in the DCs than on the floor. These findings suggest that cardiopulmonary resuscitation performed in a DC without the use of a supporting stool or stiff backboard is not likely to be effective even if a DC design that incorporates a supportive steel column is utilized.

Risks of Aerosol Contamination in Dental Procedures during the Second Wave of COVID-19-Experience and Proposals of Innovative IPC in Dental Practice.

Dental-care workers operate very close to the patient's mouth and are at high risk of contamination by SARS-CoV-2. Droplets may be contaminated by patient's saliva and exhaled breath particles. All asymptomatic patients should be considered as Coronavirus positive. All dental procedures must be revised after positive identification of SARS-Cov-2. Novel recommendations as the use of novel suction cannula designed for fast spray/saliva aspiration, use of Tyvek suits and innovative sprayhoods designed for dental-care worker protections are proposed to prevent virus transmission. New tailored operative and clinical procedures are being currently developed by university dental clinics and hospitals in attempt to reduce risk for dental workers and patients.

Postgraduates' Perspective of Pediatric Dental Chair: A Questionnaire Study.

The posture and positioning of pediatric dentist will greatly depend upon the type of dental chair they chose while treating children. Pediatric dentists working on a traditional adult chair for treating children frequently lean forward for close proximity to oral cavity; as a result of this poor posture, they are more prone to suffer from musculoskeletal disorders. Proper positioning of dentist during treatment will improve not only their comfort but also their career longevity. The aim of the study was to assess the comfort and need of pediatric dental chair compared with traditional adult dental chair for treatment and better management of children. STUDY DESIGN: This is a questionnaire survey for postgraduate students consisting of 14 multiple-choice questions in English format. The questionnaire was structured to know whether the pediatric dental chair is beneficial compared to traditional adult dental chair while treating children. RESULTS AND CONCLUSION: Out of 92 responded members, 99% had an opinion that a pediatric dental chair is needed for treating children. They concluded that pediatric dental chair had many advantages over traditional adult dental chair while treating children and acceptance of pediatric dental chair among postgraduates is overwhelming. HOW TO CITE THIS ARTICLE: Reddy ER, Raju SS, Merum K, et al. Postgraduates' Perspective of Pediatric Dental Chair: A Questionnaire Study. Int J Clin Pediatr Dent 2020;13(3):251-254.

Efficacy of water filters for dental chair units: assessment of the filtration action versus Coxsackievirus B5.

INTRODUCTION: The microbiological safety and control of the water used in dental practice has a critical importance for avoiding cross-linked infections in the dental office. The aim of this study was to establish coxsackie virus filtration of the water applied to a dental unit. METHODS: A specific water filter-system was used, to verify the viral load in the outgoing water. The statistical analysis was performedusing the Shapiro-Wilk and t-Student test. RESULTS: The outcome of the evaluation of the virologic tests shows an excellent capability of virus filtration that attested 99.9999% in the volume analyzed. A statistical difference was found in the bacterial water contamination parameter before and after filtration. (P = 0.000000). CONCLUSIONS: According to the tests, medical devices applied to a dental unit are able to filter viruses and therefore reduce risk of contamination in the dental office.

Evaluation of the simulator with automatic irrigation control system designed for countermeasures of internal contamination in dental unit water lines.

The prevention of nosocomial infections is an imperative task. The dental chair unit (DCU) is an indispensable device used in dental treatment. However, it is known that the dental unit water line (DUWL) can become contaminated with biofilm, consisting mainly of heterotrophic bacteria (HB). Recently, the International Organization for Standardization specified the methods for testing DUWL contamination management. On these grounds, a simulator reproducing DUWL was prepared to standardize the examination method of the DUWL contamination. OBJECTIVES: To evaluate the reproducibility of the DUWL simulator, monitor the DUWL contamination states, and test the efficacy of a commercial decontaminant for DUWL. METHODS: The DUWL simulator was assembled by a DCU manufacturing company. The simulator's DUWL was filled with tap water (TW), and left for approximately one year. Neutral electrolyzed water (NEW) was used as a decontaminant for DUWL. Both TW and NEW were passed through DUWL in a timely manner simulating daily dental treatment. Water was sampled from the air turbine hand piece weekly for 4 weeks and used for HB culture. Contamination status was evaluated by measuring bacterial adenosine triphosphate release and by culturing on Reasoner's 2A medium. RESULTS: The DUWL released contaminated water had a bacterial count of over 6 × 104 cfu/mL. After passing NEW through DUWL for 1 week, the count drastically decreased to its basal level and remained steady for 4 weeks. However, TW showed no effect on DUWL decontamination throughout the examination periods. CONCLUSIONS: The DUWL simulator could be useful to examine the efficacy of the decontaminant for DUWL and development of new methods in DUWL contamination management.

Efficacy of BRS® and Alpron®/Bilpron® Disinfectants for Dental Unit Waterlines: A Six-Year Study.

Biofilms in dental unit waterlines (DUWL) are a potentially significant source of contamination posing a significant health risk as these may come into contact with patients and dental staff during treatment. The aim of this study was to evaluate the microbiological quality of DUWL water treated by Biofilm-Removing-System® (BRS®) and Alpron®/Bilpron® disinfectant solutions for six years in a French university hospital. The microbiological quality of water supplied by 68 dental units-initially shock treated with BRS®, then continuously treated by Alpron® with sterile water during working days and Bilpron® during inactivity period, and combined with purging every morning and after each patient-was assessed biannually during six years for total culturable aerobic bacteria at 22 °C and 36 °C, Legionella sp., Pseudomonas aeruginosa, and total coliforms. A total of 628 samples were analyzed, 99.8% were compliant with extended microbiological levels, and we never detected pathogen bacteria like Legionella sp. and P. aeruginosa. Only one sample (0.2%) was noncompliant with the level of total culturable aerobic bacteria at 36 °C, which exceeded 140 colony forming units per mL. The protocol implemented in our university hospital gives excellent results and enables control of the microbiological quality of DUWL water in the long term.

[Efficacy of Slightly Acidic Electrolyzed Water against Contamination of Water Line of Dental Units].

OBJECTIVES: The purpose of this study was to evaluate the efficacy of slightly acidic electrolyzed water (SAEW) against the contamination of the water line of dental units and the effects of SAEW on the water line. MATERIALS AND METHODS: The experimental material was a prototype dental unit equipped with a SAEW generator. SAEW is directly supplied to each device or part of this unit system. Experimental SAEW samples were collected from a high-speed handpiece (HS-1), an ultrasonic scaler, and a cup filler of the prototype dental unit. Control samples were taken before and after the prescribed flushing from another high-speed handpiece (HS-2) that is directly supplied with tap water in the same dental unit. The samples were analyzed for free chlorine and heterotrophic bacteria for 7 years to assess the efficacy and effects of SAEW. The substances eluted in SAEW were examined to investigate the effect of SAEW on the water line. A questionnaire survey was conducted on patients on whom dental uints supplied with SAEW were used. RESULTS: SAEW always showed a higher free chlorine concentration than tap water during the observation period of 7 years. In HS-2 supplied with tap water, the free chlorine concentration increased significantly owing to the prescribed flushing. SAEW always showed a significantly smaller number of heterotrophic bacteria than tap water. No abnormal levels values of water line components eluted into SAEW were observed. There were few negative comments from patients on whom dental units supplied with SAEW were used. CONCLUSIONS: SAEW continuously used for 7 years was effective for contamination control in the water line of dental units.

Development of modified dental chair to accomodate both wheelchair bound patients and general population.

Background: Dental chairs are a vital tool in modern dentistry. Their design has paved the way for increasing improvement in dental treatment. Since the 1900's, the dental chair design has continuously evolved and transformed from manually operated mechanisms to recently automated mechanism, in spite of advancements a common obstacle faced by these wheelchair bound populations in using present dental chair is transfer. Wheelchair users need to be transferred from the wheelchair to other places many times a day. In most of the cases the wheelchair user does not possess the capability of transferring to a dental chair independently. Therefore assistance is needed either from dental clinic staff or from family and friends. This transfer of patients from wheelchair not just requires manpower but also creates unnecessary anxiety among the wheel chair bound patients.Solution: Thus a modified dental chair was constructed which would accommodate the wheelchair bound patients to the dental chair without any transfer. This study highlights the mechanism of action of the modified dental chair.Implication for rehabilitationImprove access among wheelchair bound patients to dental care servicesDecreases anxiety among the disadvantaged population in clinical set up.

Dental Unit Waterlines: A Survey of Practices in Eastern France.

Water is essential during dental care. Physical and chemical techniques should be used to maintain a good water quality with respect to bacteria, and to ensure the safety of exposed patients and dental staff. The aim of this survey was to assess the modalities used by dental practitioners in Eastern France to maintain the water quality of their dental unit waterlines (DUWLs). A questionnaire about water quality maintenance practices was sent to 870 dental offices in 2016. The questionnaires were completed by 153 dental offices, covering about 223 dental care units. The majority of units were fed by mains water (91.0%), which is generally unfiltered (71.3%). One-third (33.6%) of the units had an independent water bottle reservoir. Flushing, a basic physical technique to improve the quality of units' outflow water, was practiced in 65.4% of dental offices. Concerning the chemical treatment of water, it was used for 62.1% of the units. An analysis of the microbiological quality of the DUWL water was only carried out in 2.6% of the offices. In conclusion, providing better training to dental staff seems necessary to improve their practices and to generalize procedures that improve the microbiological quality of the water used.

Effectiveness and safety of low-concentrated ozonized water for the reduction of contamination in dental unit water lines.

Contamination of dental unit waterlines (DUWL) with heterotrophic bacteria can cause problems in immune compromised patients (aged, tumor and organ transplantation-patients). We focused on the use of low-concentrated ozonized water (OZW) as the biofilm formation restraint system for DUWL. Here, we examined the effects of low-concentrated OZW on the growth of bacteria and related biofilm formation and harmfulness to dental unit components (DUCs) in vitro. OBJECTIVES: To evaluate the bactericidal effects of OZW on biofilms in DUWL and DUC in vitro. METHODS: Low-concentrated OZW (0.4 mg/L) was generated using an OZS-PTDX generator. Heterotrophic bacterial biofilms in old DUWL tubes and Candia albicans solution (control microbe) were treated with OZW for 1 h with gentle agitation before static culturing for 96 h in Reasoner's 2A liquid media. The control solutions were 0.1% cetylpyridinium chloride (CPC), chlorinated tap water (TW), and phosphate-buffered saline (PBS). Adenosine triphosphate (ATP) amounts of the microbes were measured and the biofilms of these microbes were observed using scanning electron microscopy (SEM). Moreover, surfaces of DUC soaked in OZW and TW were observed by SEM. RESULTS: The OZW reduced ATP levels in microbes to 50% compared to TW and PBS treatment, although CPC reduced it below detection limits. SEM observation revealed deformation of microbes cultured with OZW, whereas no changes were seen on DUC surfaces. CONCLUSIONS: Low-concentrated OZW is bactericidal against heterotrophic bacteria biofilms and it is not harmful to DUC, suggesting that it might be useful in preventing DUWL contamination.

Usefulness of a stool to stabilize dental chairs for cardiopulmonary resuscitation (CPR).

BACKGROUND: Cardiopulmonary resuscitation (CPR) requires immediate start of manual chest compression (MCC) and defibrillation as soon as possible. During dental surgery, CPR could be started in the dental chair considering difficulty to move the patient from the dental chair to the floor. However, all types of dental chairs are not stable for MCC. We previously developed a procedure to stabilize a dental chair by using a stool. EUROPEAN RESUSCITATION COUNCIL (ERC) guideline 2015 adopted our procedure when cardiac arrest during dental surgery. The objective of this study was to verify the efficacy of a stool as a stabilizer in different types of dental chairs. METHODS: Three health care providers participated in this study, and 8 kinds of dental chairs were examined. MCC were performed on a manikin that was laid on the backrest of a dental chair. A stool was placed under the backrest to stabilize the dental chair. The vertical displacement of the backrest by MCC was recorded by a camcorder and measured by millimeter. Next, the vertical displacement of the backrest by MCC were compared between with and without a stool. RESULTS: In all 8 dental chairs, the method by using a stool significantly reduced the vertical displacements of the backrest by during MCC. The reduction ratio (mean [interquartile range]) varied between nearly 27 [20] and 87 [5] %. In the largest stabilization case, the displacement was 3.5 [0.5] mm with a stool versus 26 [5.5] mm without a stool (p <  0.001). CONCLUSIONS: Our procedure to stabilize dental chairs by using a stool reduced the displacement of a backrest against MCC in all chairs. CLINICAL RELEVANCE: Effective MCC could be performed in dental chairs by using a stool when sudden cardiac arrest occurs during dental surgery.