A system for predicting and preventing work-related musculoskeletal

A system for predicting and preventing work-related musculoskeletal disorders among dentists

Bhornsawan Thanathornwong , Siriwan Suebnukarn , Yupin Songpaisan & Kan Ouivirach (2012): A system for predicting and preventing work-related musculoskeletal disorders among dentists, Computer Methods in Biomechanics and Biomedical Engineering, DOI:10.1080/10255842.2012.672565
(Received 15 December 2011; final version received 1 March 2012)

Work-related musculoskeletal disorders (WMSDs) have become increasingly common among dentists and initiate a series
of events that could result in a career ending. This study aims to construct a system for predicting and preventing WMSD
among dentists. We used Bayesian network (BN) that describes the mutual relationships among multiple variables
contributing to WMSDs. The data-sets were prepared from direct measurements of dentist’s movements and a questionnaire
survey. We applied BN learning algorithms to the training data-sets to develop WMSD prediction model using 10-fold
cross-validation. To evaluate the system performance, 16 dentists were randomly assigned into a 2 £ 2 crossover trial
scheduled to each of two sequences of dental working: receiving feedback or no feedback including the probability of
WMSD and related risk factors from the system. The group that received feedback decreased significantly (t-test, p , 0.05)
the extensions of neck and upper back in the y-axis as well as the WMSD probability on the post-test. In conclusion, the
system for predicting and preventing WMSD aids the correction of neck and upper back extensions and reduction in WMSD
probability, which may potentially contribute to reduce the risk of WMSD among dentists.

Keywords: Bayesian network; work-related musculoskeletal disorders; dentist

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Variability of Musculoskeletal Strain on Dentists: An Electromyographic and Goniometric Study

David Blanc, Pierre Farre & Olivier Hamel

Introduction. Dentists and hygienists are strongly affected by musculoskeletal disorders (MSDs). As workstation concepts are supported by subjective arguments only, the aim of this study was to use objective measurements to compare the variability of strain in various concepts: a dental chair equipped with a cart or an over-the-patient delivery system without an assistant, and Dr Daryl Beach’s concept with an assistant. Methods. Goniometric and electromyographic recordings were made on 8 subjects, during a scaling operation. The electrical activity of their trapezius and lumbar muscles was compared, as were their cervical and lumbar ranges of motion. Results. The results showed that there was a wide variability depending on the workstation. However, the Beach concept tended to reduce physical strain on most parameters: duration of left lumbar muscle activity (2% compared to 15% of time spent in >10% maximal voluntary contraction, MVC), time spent in cervical side bending (4% compared to 30%), cervical flexion of >20° (9% compared to 40%), and left trapezius activity (9% of time spent >10% MVC compared to 28%). Conclusion. Practitioners and students should adjust their workstations to reduce the prevalence of MSDs.

Proper Ergonomic Positioning: It’s Only Human

As a busy private practitioner in Aurora, Colo., Dr. Michael Dougherty has a vested interest in dental ergonomics. He offers courses practical applications of ergonomic principles in dentistry, including office design, equipment selection, and working postures and behaviors. He bases all his training on the feel-based intuitive method of body and instrument positioning called proprioceptive derivation (pd). He took some time to answer some questions and his responses and observations provide valuable, practical tips for dental professionals who want to work healthier and more productively.

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Acquiring Improved Dental Performance Skills

by Michael Dougherty, DDS

Dentistry is a profession where consistent accuracy is required. A dentist’s judgment on skills, the setting where s/he practices, and the technology used affects the lives of many. Industry has taught us that to limit the adjustments and decisions a worker makes in manufacturing a product produces a product with fewer defects. Why should we think that dentistry is any different? Changing the tilting dental chair environment, which allows many adjustments and decisions, to an environment in which the dental patient support provides a stable reference for balanced operator positions limits adjustments and decisions during dental procedures and enhances the dentist’s performance. The non-tilting patient support requires advanced skills in order to function optimally.
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Ergonomic Principles are Proprioceptively Derived

by Michael Dougherty, DDS

The performance of any physical task is compromised when the setting and instruments used do not allow balanced operating positions for peak function. Past engineering has approached design innovation from the standpoint of modifying existing hardware and relocating different components in the setting to improve ergonomics and efficiency. This focus on existing hardware has made peak human potential, defined as doing the best performance of which one is capable, difficult to achieve. Dr. Daryl Beach, an American dentist residing in Japan, created a new way for dental equipment and instruments to be designed in 1962. This method he termed Performance Logic, an alternative approach to the delivery of dental services, which optimizes the performance of the dentist as s/he acts out dental procedures.

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Information for Consideration in an Ergonomic Standard for Dentistry

by Michael Dougherty, DDS

Kadowaki and Kaneco have completed studies comparing the traditional tilting dental chair environment and a new technology and process of performing dentistry that stabilizes the operator and the patient in the most optimum relationship. It is evident from their statistics that the latter is a significantly less stressful and more efficient way to practice dentistry because it resulted in significant differences in a variety of measures used to assess dental practice efficiency and efficacy.

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Ergonomic Principles in the Dental Setting: Delivery System Design (Part 1)

The Ergonomic Standard mandated by the Occupational Safety and Health Administration (OSHA) recommended that the most efficient and effective way to remedy “ergonomic hazards” causing musculoskeletal (MSK) strain should be through engineering improvements in the workstation.1 Although Congress withdrew the OSHA ergonomic regulations before they were to be implemented, Secretary of Labor Elaine Chao has promised to “pursue a comprehensive approach to ergonomics, which may include new rulemaking.” Making employers more accountable for the physical environment in which they and their employees practice in turn encourages manufacturers to develop more ergonomically designed delivery systems. Led by the American Dental Association’s “Ergonomic Summit”2 endorsement in August of 2000, dental manufacturers began to look more intently at ways to improve the ergonomics of the equipment and instruments they provide to the profession.
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Ergonomic Principles in the Dental Setting: Human-Centered Instruments, Stations and Walkways (Part 2)

In Part I of this article (see related link), two aspects of the ergonomics of dental equipment design were discussed: the need to enable operators to perform dental procedures without compromising their preferred posture and the need to operate at a specific point in space where they feel they have the best control of their fingers. To provide optimal ergonomic conditions, repositioning and avoiding objects should be kept to a minimum while operating. Determined through masked-eye testing using the proprioceptive senses of the body, these conditions are used to derive the most ergonomic design of dental equipment and instruments.
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What is the Appropriate Location of a Dental Handpiece

People don’t pay much attention to where high-speed and low-speed hand-pieces should be located before, during and after an operation, or in what position they should be. However, this is very important.
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