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Rest vertical dimension determined by electromyography with biofeedback as compared to conventional methods
Rest vertical dimension determined electromyography with biofeedback conventional methods Sylvan Feldman, D.D.S.,*
Robert J. Leupold,
D.M.D.,
M.A.,**
by as compared to and Leah M. Staling, B.S., MS.***
University of Maryland, School of Dentistry, Baltimore, Md.
Res
t vertical dimension is defined as “the length of the face when the mandible is in rest position.” Rest jaw relation is defined as “the habitual postural jaw relation when the patient is resting comfortably in an upright position and the condyles are in a unstrained position in the glenoid neutral, fossae.“’ The prosthodontist is continually confronted with problems related to the determination of rest vertical dimension when constructing complete dentures. In arriving at solutions of these problems, he usually makes use of conventional methods for determining vertical dimension such as swallowing, phonetics, and the physiologic approach. Furthermore, the dentist must comprehend the limitations incurred when using these techniques. Factors such as the individual technique, the patient’s comprehension of what the dentist is trying to accomplish, and the habit patterns of the patient’s neuromuscular mechanism have contributed to these problems in establishing the proper vertical dimension of rest. It would be beneficial if more precise methods could be devised to determine the vertical dimension of rest. This study was designed to address the determination of rest vertical dimension utilizing electromyography with biofeedback. Biofeedback’ is an ideograph that describes the phenomenon of control over internal biologic functions occurring when information about the function is “fed-back” to the person whose biologic activity is involved.
CONVENTIONAL DETERMINING
METHODS FOR VERTICAL DIMENSION
Niswonger”, 4 established rest position by having patients swallow and relax to the rest position. He *Prosthodontic **Chairman, ***Assistant
216
Postgraduate student. Department of Removable Prosthodontics. Research Professor, Department of Physiology.
AUGUST
1978
VOLUME
84
NUMBER
2
felt that rest vertical dimension is a voluntary position and that the patient can be told to find “a most comfortable position” or to place his jaw “in the rest or relaxed position.” Atwood,” in a cephalometric study, found that particular method (cephalometry) to be the most accurate for determining rest position but also found variations in measurements between sittings and within the same sitting. In making his analysis he had patients wet the lips, swallow, say “m,” and relax. Swerdlow6 felt that phonetic methods were consistently more reliable than the swallowing method for the determination of interocclusal distance. IJsing cephalometric techniques, Thompson? found the rest position to be stable and unalterable. Lytle8 used a central bearing device to establish a tentative vertical dimension of occlusion, employing the patient’s neuromuscular perception. This sampling of the literature illustrates the variability of methods and results and emphasizes the importance of finding a procedure that is more precise.
ELECTROMYOGRAPHY Moyer? described the physiologic rest position as the postural position of the mandible. Hickey and associates” used electromyography along with radiographs and found no significant difference in the rest position at the same sitting or between sittings, in contrast to Atwood’s findings. Garniek and Ramfjord” found a resting range of 11.1 mm using electromyography. Shpuntoff and Shpuntoff’ used the masseter muscle to determine, by electromyography with visual feedback control (biofeedback), the rest position of 215 patients with dentulous mouths. They found this method to be accurate and effective. Krajicek and associates’:’ checked the accuracy of CG’Z-3913/78/0240-0216$00.40/O
0 1978
The
C. V. Mosby
Co.
VERTICAL
DIMENSION
USING
BIOFEEDBACK
Fig. 1. The electrodes are affixed to the skin of one of the subjects. obtaining the mandibular rest position using the Pleasure method (conventional) through electromyography with visual feedback control. They determined that this method produced satisfactory results. The literature is replete with electromyographic studies of rest position but is lacking in reports of investigations that compare electromyographic findings utilizing biofeedback with surface electrodes on the temporal muscles to findings that use conventional methods in determining rest vertical dimension. Initial attempts to use the masseter muscles in this study, as did KrajicekX3 and Shpuntoff,” resulted in electromyography registrations that were not as discernible as the temporal muscles.
PURPOSE This study was undertaken to determine if electromyography with biofeedback’* can be utilized to produce a more reliable determination of rest vertical dimension than conventional methods. The study was limited to determinations of rest vertical dimension in the edentulous patient by electromyography with biofeedback as compared with phonetic and swallowing methods.
METHODS
AND MATERIALS
Five edentulous subjects were selected for the study. Each subject underwent determination of the vertical dimension of rest utilizing conventional methods, i.e., swallowing and phonetics.” These determinations were carried out by three different dentists, each independent of the others, and the results were recorded by measuring from triangles of tape affixed to the nose and chin using a caliper measuring device. THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 2. Textronix cathode ray oscilloscope.
Fig. 3. A Polaroid camera with adapter was used for photographing the oscilloscope screen. Each subject, still seated in a dental chair with a rigid adjustable headrest, had electromyographic electrodes affixed to the skin over both anterior temporal muscles (Fig. 1). Clip electrodes were affixed to each ear lobe and a fifth electrode to the peak of the forehead as a ground for the circuits. The electrodes were connected to a Textronix cathode ray oscilloscope* electromyographic unit with two channels connected to an oscilloscope (Fig. 2). The oscilloscope screen had its rim adapted to receive a Polaroid camerat in a fixed repeatable position to enable the standardized photographing of screen images at any given time (Fig. 3). Each subject was rehearsed in the use of biofeedback. To accomplish this, the patients faced a mirror that enabled them to observe their muscular potential on the oscilloscope screens. This allowed the subjects to place their mandible in a position where *Textronix, fPolaroid
Inc., Portland, Ore. Corp.. Cgmbridge, .Mass. 217
FELDMAN,
Dentist
Dentist
1
2
3
AND
3
1
Patient Dentist
LEUPOLD.
STALlNG
5 69mrr
72mm 72
66mm 65
66
62mm 62 63
73
65
69
66 t6
66 66
73 73
63 64
71 71
66
67
73
64
70
64.5
60 60
60
69
60 61
66
60.5
73 71 72
65.7
82.9
72.4
63.1
69.2
65
83
66mm 66
66.5 66.0
70
68
Mean :onuentional VIeasurement
Fig. 4. Photograph of oscilloscope reading of muscular potential as determined using electromyographic biofeedback. the least amount of muscular activity could be observed. One investigator measured the nose-tochin distance and the other photographed the oscilloscope image when maximum biofeedback position was achieved (Fig. 4). This biofeedback measurement allowed a comparison to be made with the mean conventional measurement of rest vertical dimension. RESULTS To determine a mean figure for conventional measurements which could be compared with biofeedback determinations, the data for each patient were combined and an average calculated (Fig. 5). All five patients were found to have a mean rest vertical dimension that was within 1.2 mm of the biofeedback-determined rest vertical dimension. Although a discrepancy of 1.2 mm in the vertical dimension of rest for complete dentures may be tolerated by many patients, major individual differencesin measurementsbeyond the mean of 1.2 mm were found between participating dentists and in patients No. 2 and No. 4. Differences in measurements of as much as 6 mm were found in patients No. 2 and No. 4. This could potentially have a deleterious effect upon the successful outcome of complete denture treatment. Biofeedback electromyography consistently came within 1.2 mm of the mean of the measurementsof rest vertical dimension asdetermined by conventional methods.
Biofeedback
Fig. 5. Compilation of conventional and biofeedback measurements. produce a more reliable determination of rest vertical dimension than conventional methods such as phonetics and swallowing. It was found that: 1. Electromyography with biofeedback appeared to produce a more consistently reliable determination of rest vertical dimension than conventional methods when used with edentulous subjects. 2. Determinations of rest vertical dimension by individual dentists using phonetics and swallowing had wide variations in two of the five patients in a range of up to 6 mm. An error of this magnitude could easily causean intrusion upon the interocclusal distance and resultant failure of treatment. Since this study was limited to five patients, a more expanded study is necessary to determine the validity of electromyography vs. conventional methods for determining rest vertical dimension. Both methods have questionable aspectsin relation to the time of day, patient’s understanding of each technique, and past dental history. However, the most critical problem of the electromyographic technique is the feasibility of its usein a private practice in light of the excessivecost of the required equipment. REFERENCES 1. 2.
AND CONCLUSIONS
This study was undertaken to determine if electromyography with biofeedback can be utilized to
Glossary
of Prosthodontic Terms, ed 4. J PROSTHEX DENT 1977. Brown, B.: Biofeedback: An exercise in “self-control.” Saturday Review March 22, 1975, pp 22-27. Niswonger, M. E.: The rest position of the mandible and the centric relation. J Am Dent Assoc 21:1572, 1934. Niswonger, M. E.: Obtaining vertical relation in edentulous cases that existed prior to extraction. J Am Dent Assoc 25:1842, 1938. 38:66,
3.
SUMMARY
64
Measurement
4.
AUGUST
1978
VOLUME
40
NUh4BER
2
VERTICAL
DIMENSION
USING
BIOFEEDBACK
5. Atwood,
D. A.: A critique of research of the rest position. J DENT 16:848, 1966. Swerdlow, H.: Vertical dimension-Literature review. J PR~STHET DENT 15:241, 1965. Thompson, J. R.: The rest position of the mandible and its significance to dental science. J Am Dent Assoc 33:151, 1946. Lytle, R.: Vertical relation and neuromuscular perception. J PROS-WET DENT 1412, 1964. Meyers, R. E.: Some physiologic considerations of centric and other jaw relations. J PROSTHET DENT 6: 183, 1956. Hickey, J. C., Williams, B. H., and Woelfel, J. B.: Stability of mandibular rest position. ,J PR~~THET DENT 11:566, 1956. Garnick, J., and Ramfjord, S.: Rest position-An electromyographic and clinical investigation. J PROSTHET DENT 12:895, 1962. Shpuntoff, H., and Shpuntoff, W.: A study of physiologic
rest position
PRWXHET
6. 7.
8. 9. 10. 11.
12.
ARTICLES
TO APPEAR IN FUTURE
and centric position by electromyography. J 6:621, 1956. Krajicek, D., Jones, P., Radzyminski, S., Rose, D., and Unti, I?.: Clinical and electromyographic study of mandibular rest position. J PROSTHET DENT I1:826, 1961. Melzak, R.: The promise of biofeedback: Don’t hold the party yet. Psychology Today July, 1955, p I& Silverman, M. M.: Pre-extraction record to avoid premature aging of the denture patient. .J PRWIHEI. DFNT 5:465, PROSTHET
13.
14. 15.
DENT
1955.
Reprint requsts to: DR.
ROBERT
J. LEUPOI.D
UNIVERSITY OF MARYLAND SCHOOL OF DENTISTRY
666 W. BALTIMORE BALTIMORE,,
MD.
ST. 21201
ISSUES
Direct pattern technique for posts and cores Amp W. Miller,
III, D.D.S.
Cl&&al evaluation of cement solubiiity John C. Mitchem,
D.M.D.,
MS.,
and D. G. Gronas, D.D.S.
A comparison of properties for zinc phosphate cements mixed on room m and frozen slabs C. Louis Myers, M.S., D.D.S., John T. Drake, D.D.S., MS.,
and William
A. Brantley,
Ph.D.
Etio@ic factors in the denture sore mouth syndrxnne J. P. Nater, M.D., N. H. Groenman, L. H. Timmer, D.D.S.
Ph.D., B. G. Wakkers-Garritsen,
The myofascbl pain-dysfunction
M.D., and
syndrome
Harmes Nel, M.Ch.D.
CyvlapGylate
as a cavity liner for amalgam restorations
Sheldon M. Newman, THE
JOURNAL
OF PROSTHETIC
D.D.S., Steven K. Valadez,
DENTISTRY
D.D.S., and John H. Hembree, Jr., D.D.S. 219
Robert J. Leupold,
D.M.D.,
M.A.,**
by as compared to and Leah M. Staling, B.S., MS.***
University of Maryland, School of Dentistry, Baltimore, Md.
Res
t vertical dimension is defined as “the length of the face when the mandible is in rest position.” Rest jaw relation is defined as “the habitual postural jaw relation when the patient is resting comfortably in an upright position and the condyles are in a unstrained position in the glenoid neutral, fossae.“’ The prosthodontist is continually confronted with problems related to the determination of rest vertical dimension when constructing complete dentures. In arriving at solutions of these problems, he usually makes use of conventional methods for determining vertical dimension such as swallowing, phonetics, and the physiologic approach. Furthermore, the dentist must comprehend the limitations incurred when using these techniques. Factors such as the individual technique, the patient’s comprehension of what the dentist is trying to accomplish, and the habit patterns of the patient’s neuromuscular mechanism have contributed to these problems in establishing the proper vertical dimension of rest. It would be beneficial if more precise methods could be devised to determine the vertical dimension of rest. This study was designed to address the determination of rest vertical dimension utilizing electromyography with biofeedback. Biofeedback’ is an ideograph that describes the phenomenon of control over internal biologic functions occurring when information about the function is “fed-back” to the person whose biologic activity is involved.
CONVENTIONAL DETERMINING
METHODS FOR VERTICAL DIMENSION
Niswonger”, 4 established rest position by having patients swallow and relax to the rest position. He *Prosthodontic **Chairman, ***Assistant
216
Postgraduate student. Department of Removable Prosthodontics. Research Professor, Department of Physiology.
AUGUST
1978
VOLUME
84
NUMBER
2
felt that rest vertical dimension is a voluntary position and that the patient can be told to find “a most comfortable position” or to place his jaw “in the rest or relaxed position.” Atwood,” in a cephalometric study, found that particular method (cephalometry) to be the most accurate for determining rest position but also found variations in measurements between sittings and within the same sitting. In making his analysis he had patients wet the lips, swallow, say “m,” and relax. Swerdlow6 felt that phonetic methods were consistently more reliable than the swallowing method for the determination of interocclusal distance. IJsing cephalometric techniques, Thompson? found the rest position to be stable and unalterable. Lytle8 used a central bearing device to establish a tentative vertical dimension of occlusion, employing the patient’s neuromuscular perception. This sampling of the literature illustrates the variability of methods and results and emphasizes the importance of finding a procedure that is more precise.
ELECTROMYOGRAPHY Moyer? described the physiologic rest position as the postural position of the mandible. Hickey and associates” used electromyography along with radiographs and found no significant difference in the rest position at the same sitting or between sittings, in contrast to Atwood’s findings. Garniek and Ramfjord” found a resting range of 11.1 mm using electromyography. Shpuntoff and Shpuntoff’ used the masseter muscle to determine, by electromyography with visual feedback control (biofeedback), the rest position of 215 patients with dentulous mouths. They found this method to be accurate and effective. Krajicek and associates’:’ checked the accuracy of CG’Z-3913/78/0240-0216$00.40/O
0 1978
The
C. V. Mosby
Co.
VERTICAL
DIMENSION
USING
BIOFEEDBACK
Fig. 1. The electrodes are affixed to the skin of one of the subjects. obtaining the mandibular rest position using the Pleasure method (conventional) through electromyography with visual feedback control. They determined that this method produced satisfactory results. The literature is replete with electromyographic studies of rest position but is lacking in reports of investigations that compare electromyographic findings utilizing biofeedback with surface electrodes on the temporal muscles to findings that use conventional methods in determining rest vertical dimension. Initial attempts to use the masseter muscles in this study, as did KrajicekX3 and Shpuntoff,” resulted in electromyography registrations that were not as discernible as the temporal muscles.
PURPOSE This study was undertaken to determine if electromyography with biofeedback’* can be utilized to produce a more reliable determination of rest vertical dimension than conventional methods. The study was limited to determinations of rest vertical dimension in the edentulous patient by electromyography with biofeedback as compared with phonetic and swallowing methods.
METHODS
AND MATERIALS
Five edentulous subjects were selected for the study. Each subject underwent determination of the vertical dimension of rest utilizing conventional methods, i.e., swallowing and phonetics.” These determinations were carried out by three different dentists, each independent of the others, and the results were recorded by measuring from triangles of tape affixed to the nose and chin using a caliper measuring device. THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 2. Textronix cathode ray oscilloscope.
Fig. 3. A Polaroid camera with adapter was used for photographing the oscilloscope screen. Each subject, still seated in a dental chair with a rigid adjustable headrest, had electromyographic electrodes affixed to the skin over both anterior temporal muscles (Fig. 1). Clip electrodes were affixed to each ear lobe and a fifth electrode to the peak of the forehead as a ground for the circuits. The electrodes were connected to a Textronix cathode ray oscilloscope* electromyographic unit with two channels connected to an oscilloscope (Fig. 2). The oscilloscope screen had its rim adapted to receive a Polaroid camerat in a fixed repeatable position to enable the standardized photographing of screen images at any given time (Fig. 3). Each subject was rehearsed in the use of biofeedback. To accomplish this, the patients faced a mirror that enabled them to observe their muscular potential on the oscilloscope screens. This allowed the subjects to place their mandible in a position where *Textronix, fPolaroid
Inc., Portland, Ore. Corp.. Cgmbridge, .Mass. 217
FELDMAN,
Dentist
Dentist
1
2
3
AND
3
1
Patient Dentist
LEUPOLD.
STALlNG
5 69mrr
72mm 72
66mm 65
66
62mm 62 63
73
65
69
66 t6
66 66
73 73
63 64
71 71
66
67
73
64
70
64.5
60 60
60
69
60 61
66
60.5
73 71 72
65.7
82.9
72.4
63.1
69.2
65
83
66mm 66
66.5 66.0
70
68
Mean :onuentional VIeasurement
Fig. 4. Photograph of oscilloscope reading of muscular potential as determined using electromyographic biofeedback. the least amount of muscular activity could be observed. One investigator measured the nose-tochin distance and the other photographed the oscilloscope image when maximum biofeedback position was achieved (Fig. 4). This biofeedback measurement allowed a comparison to be made with the mean conventional measurement of rest vertical dimension. RESULTS To determine a mean figure for conventional measurements which could be compared with biofeedback determinations, the data for each patient were combined and an average calculated (Fig. 5). All five patients were found to have a mean rest vertical dimension that was within 1.2 mm of the biofeedback-determined rest vertical dimension. Although a discrepancy of 1.2 mm in the vertical dimension of rest for complete dentures may be tolerated by many patients, major individual differencesin measurementsbeyond the mean of 1.2 mm were found between participating dentists and in patients No. 2 and No. 4. Differences in measurements of as much as 6 mm were found in patients No. 2 and No. 4. This could potentially have a deleterious effect upon the successful outcome of complete denture treatment. Biofeedback electromyography consistently came within 1.2 mm of the mean of the measurementsof rest vertical dimension asdetermined by conventional methods.
Biofeedback
Fig. 5. Compilation of conventional and biofeedback measurements. produce a more reliable determination of rest vertical dimension than conventional methods such as phonetics and swallowing. It was found that: 1. Electromyography with biofeedback appeared to produce a more consistently reliable determination of rest vertical dimension than conventional methods when used with edentulous subjects. 2. Determinations of rest vertical dimension by individual dentists using phonetics and swallowing had wide variations in two of the five patients in a range of up to 6 mm. An error of this magnitude could easily causean intrusion upon the interocclusal distance and resultant failure of treatment. Since this study was limited to five patients, a more expanded study is necessary to determine the validity of electromyography vs. conventional methods for determining rest vertical dimension. Both methods have questionable aspectsin relation to the time of day, patient’s understanding of each technique, and past dental history. However, the most critical problem of the electromyographic technique is the feasibility of its usein a private practice in light of the excessivecost of the required equipment. REFERENCES 1. 2.
AND CONCLUSIONS
This study was undertaken to determine if electromyography with biofeedback can be utilized to
Glossary
of Prosthodontic Terms, ed 4. J PROSTHEX DENT 1977. Brown, B.: Biofeedback: An exercise in “self-control.” Saturday Review March 22, 1975, pp 22-27. Niswonger, M. E.: The rest position of the mandible and the centric relation. J Am Dent Assoc 21:1572, 1934. Niswonger, M. E.: Obtaining vertical relation in edentulous cases that existed prior to extraction. J Am Dent Assoc 25:1842, 1938. 38:66,
3.
SUMMARY
64
Measurement
4.
AUGUST
1978
VOLUME
40
NUh4BER
2
VERTICAL
DIMENSION
USING
BIOFEEDBACK
5. Atwood,
D. A.: A critique of research of the rest position. J DENT 16:848, 1966. Swerdlow, H.: Vertical dimension-Literature review. J PR~STHET DENT 15:241, 1965. Thompson, J. R.: The rest position of the mandible and its significance to dental science. J Am Dent Assoc 33:151, 1946. Lytle, R.: Vertical relation and neuromuscular perception. J PROS-WET DENT 1412, 1964. Meyers, R. E.: Some physiologic considerations of centric and other jaw relations. J PROSTHET DENT 6: 183, 1956. Hickey, J. C., Williams, B. H., and Woelfel, J. B.: Stability of mandibular rest position. ,J PR~~THET DENT 11:566, 1956. Garnick, J., and Ramfjord, S.: Rest position-An electromyographic and clinical investigation. J PROSTHET DENT 12:895, 1962. Shpuntoff, H., and Shpuntoff, W.: A study of physiologic
rest position
PRWXHET
6. 7.
8. 9. 10. 11.
12.
ARTICLES
TO APPEAR IN FUTURE
and centric position by electromyography. J 6:621, 1956. Krajicek, D., Jones, P., Radzyminski, S., Rose, D., and Unti, I?.: Clinical and electromyographic study of mandibular rest position. J PROSTHET DENT I1:826, 1961. Melzak, R.: The promise of biofeedback: Don’t hold the party yet. Psychology Today July, 1955, p I& Silverman, M. M.: Pre-extraction record to avoid premature aging of the denture patient. .J PRWIHEI. DFNT 5:465, PROSTHET
13.
14. 15.
DENT
1955.
Reprint requsts to: DR.
ROBERT
J. LEUPOI.D
UNIVERSITY OF MARYLAND SCHOOL OF DENTISTRY
666 W. BALTIMORE BALTIMORE,,
MD.
ST. 21201
ISSUES
Direct pattern technique for posts and cores Amp W. Miller,
III, D.D.S.
Cl&&al evaluation of cement solubiiity John C. Mitchem,
D.M.D.,
MS.,
and D. G. Gronas, D.D.S.
A comparison of properties for zinc phosphate cements mixed on room m and frozen slabs C. Louis Myers, M.S., D.D.S., John T. Drake, D.D.S., MS.,
and William
A. Brantley,
Ph.D.
Etio@ic factors in the denture sore mouth syndrxnne J. P. Nater, M.D., N. H. Groenman, L. H. Timmer, D.D.S.
Ph.D., B. G. Wakkers-Garritsen,
The myofascbl pain-dysfunction
M.D., and
syndrome
Harmes Nel, M.Ch.D.
CyvlapGylate
as a cavity liner for amalgam restorations
Sheldon M. Newman, THE
JOURNAL
OF PROSTHETIC
D.D.S., Steven K. Valadez,
DENTISTRY
D.D.S., and John H. Hembree, Jr., D.D.S. 219