by Harold L. Meador, D.D.S., B.S.D., F.A.A.P.
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by Harold L. Meador, D.D.S., B.S.D., F.A.A.P. |
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| ABSTRACT PURPOSE. The possible link between occupational pain in dental hygienists and instrumentation techniques is a subject of considerable interest. The purpose of this study was to evaluate differences in patterns of muscle activity in instrumentation techniques, to better understand the impact on the practicing hygienist, and how it relates to occupational pain. METHODS. The hygienist in this case study was skilled in two instrumentation techniques, each based on different ergonomic and orthopaedic principles. Surface electrodes were placed on the flexor and extensor muscle groups of the shoulder, upper arm, forearm, two long fingers and thumb. Muscle activity in six motions common to the two techniques was recorded on an eight channel J & J model I-330 EMG system. RESULTS. Computer tracings revealed a marked difference in patterns of muscle activity between the four motions used in the newly introduced BioCentric Technique. The two motions advocated in the techniques as taught in many dental hygiene programs showed marked similarities. Subtlety is the unique feature of the relationship between these techniques that makes it difficult for even experienced operators to understand at first. CONCLUSIONS. The results of this case study are consistent with the theory that motions utilizing the same muscles cause unnecessary fatigue. The similarity in patterns of muscle activity in the currently accepted techniques may contribute to fatigue and pain as observed in the clinical hygienist. The consequences are well documented in the literature. Suggestions for corrective action were necessary for this paper to be helpful to the practicing hygienist. KEY WORDS. Carpal tunnel syndrome, occupational pain, ergonomic and orthopaedic principles in periodontal instrumentation, neutrality of joints, muscle dynamics, instrument grasp/grip. CARDINAL POINTS. The length of this section was dictated by the information required to properly cover such a complicated subject. The amount of detail tends to bury the critical issues. The reader searching for basic information should watch for these two points of a very pragmatic nature which are the foundation of the BioCentric Technique. - Neutrality of the joints of the upper extremity is absolutely essential. The exclusive use of the intra-oral fulcrum must give way to equal use of extra-oral stabilization to facilitate joint neutrality. - The use of the large muscles of the arm and shoulder in a work/rest mode is necessary to avoid exhaustion. *The data from the two articles comprising Chapters III and IV were truncated and combined in one article {38}. These CARDINAL POINTS are explained in detail in the text of the paper. The purposes of this paper are: (1) to briefly review the anatomy and physiology of the upper extremity (2) to compare muscle activity in the motions employed by different instrumentation techniques (3) to relate this data to the clinical setting and discuss the impact on the practicing hygienist with suggestions for corrective action. CASE STUDY This is a case study of one hygienist who was trained in a technique similar to the BioCentric Technique and practiced as an expanded-duties hygienist for many years. After joining the faculty of an accredited school of dental hygiene, she was required to learn the currently accepted techniques. An eight-channel J & J model I-330 EMG system was used to record muscle activity in six motions that are common to two different instrumentation techniques. The six instrumentation motions to be studied can be described as follows: 1 - 4 are the four power strokes in the BioCentric Technique {1}. The three basic power strokes are described in chapter II: The BioCentric Technique.
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  © 2001 UTHSCSA CDE. All rights reserved. |
