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Telemetric determination of anteroposterior functional occlusal contact positions—A preliminary report
Telemetric cletermination of anteqswterior occlusal contact positions-A miw
fundimd report
James A. Schorn, D.D.S., M.S.D.,* and Richard J. Goodkind, D.M.D., University of Minnesota, School of Dentistry, Minneapolis, Minn.
M.S.**
A
fter many years of research on centric relation and acquired occlusal positions (centric occlusion), a divergence of opinion still exists concerning the anteroposterior functional occlusal contact position. 1-8 This divergence has led to much controversy and to many discussions regarding restoration for the prosthodontic patient. The need to acquire knowledge to aid in the solution of this controversy was the reason for this study. For dentists, “. . . the maintenance and restoration of normal physiology of the stomatognathic system can best be achieved if procedures are based on knowledge of normal function.“9 To acquire this knowledge, scientific methodology must be applied to research. Part of this methodology requires investigative tools which deliver statistically reliable and valid information about subject or investigator variables under examination. Intraoral telemetry is one tool which has been utilized in research on occlusion. Relatively little information has been received concerning the anteroposterior functional occlusal contact position. Most of this information has not been reliable enough to make definitive statements about normal function in all patients. It was the purpose of this study to report information received from miniature intraoral telemetry equipment employed to examine anteroposterior functional occlusal contact positions. With more information available to dentists, perhaps they can better understand normal function and, consequently, prescribe modes of treatment. METHOD Three phases of investigation+ a mildly symptomatic mandibular This article is a summary of Master of Science from the University Read
before
*Assistant
**Professor tPersona1 May, 1972.
176
the American Professor, and
Director
a thesis presented of Minnesota.
Prosthodontic
Division
communication:
were conducted on one subject who demonstrated shift from centric relation to centric occlusion. In
Society,
in
partial
Chicago,
fulfillment
of
the
degree
Ill.
of Prosthodontics.
of Graduate Dr.
James
Prosthodontics. Butler,
Associate
Professor,
University
of Minnesota,
of
Telemetric
determination
Fig.
components
1. The
of occlusal
of the
contact positions 177
transmitter.
the first phase, occlusal-point contact on a line from centric relation to centric occlusion was examined on the subject’s unaltered occlusal scheme. This was done by inserting a removable telemetry transmitter* pontic into two fixed crowns which duplicated the subject’s original anatomy. In Phase 2, a complete occlusal adjustment was performed. Contact on the original transmitter switch was then recorded to be compared with Phase 1 data. In the final phase of investigation, a complete posterior reconstruction was prepared with centric occlusion coincident with centric relation. In addition, light anterior tooth contact on the subject’s canines was provided when the posterior crowns occluded. A new transmitter was fabricated and used to record centric relation contact during mastication and deglutition. EQUIPMENT This study utilized a transmitter and receiving antenna like those used by Roeber and associates8 The transmitter consisted of a battery, a multilayered switch, and an oscillator which broadcasts on three frequencies (Fig. 1). These multiple frequencies allowed alignment of the switch to determine anteroposterior contacts on a line from centric relation (one frequency) to centric occlusion (a different frequency). The receivers used were similar to those used by Roeber and associates.8 However, the recording apparatus differed. A two-channel, 60 cycle oscillograph was used. An amplifier was made to discriminate the three possible transmitter frequencies on one oscillograph channel.* This was accomplished by causing a different amplitude of stylus deflection for each frequency. The second oscillograph channel was used to *Personal communication: Minnesota, Minneapolis, Minn.,
Mr. Robert Oct., 1972.
Borher,
Department
of Biophysics,
University
of
178
Schorn
and
J. Prosthet. February,
Goodkind
Dent. 1971
Fig. 2. A graphic record of Phase 1. At the right are the three possible frequencies on a path during jaw manipulation. Greatest deflection was centric relation, and the least deflection was centric occlusion. At the far left is an illustration of cross over between frequencies (an electronic complication which was easily detected when it occurred on the records). manually record chewing strokes. A timer-marker was used to manually record swallowing episodes. Phase 1 began with mounting of diagnostic casts and verifying of all records on a completely adjustable articulator (D5AF) .+ Zinc oxide/eugenol paste was used to make an interocclusal record with the teeth in centric occlusion. The lower left second molar and left second premolar were prepared for complete crowns. Cast gold retainers, which duplicated the original occlusal scheme, were fabricated from patterns formed by painting acrylic resin into the previously fabricated occlusal index. Stern’s 0.096 inch precision attachments? were inserted into the retainers to hold a removable transmitter pontic which replaced the lower left first molar. The upper left first molar was prepared for a complete cast coping from which a switch contactor (No. 80 Endopostt) was extended to represent a mesiolingual cusp tip. Accuracy of the duplication procedure was checked by comparing preoperative and postinsertion verification records. A Vericheck* instrument was used for this procedure. Before the transmitter was completely assembled for placement in the mouth of the subject, the switch was ground into occlusion. This was done on the articulator. A dull, pointed incisal pin cast from type III gold alloy was used to customize an acrylic resin incisal guide table. A turbine handpiece, with a No. j/2 round bur placed in the position of the switch contactor, was fastened to the upper member of the articulator-.$ The switch was ground in, and working casts were occluded. The transmitter was then assembled and bench tested before completing Phase 1 with the subject. In Phase 2, a complete occlusal adjustment was performed on the subject’s dentition. An approximate 3 mm. forward and upward slide from centric relation to centric occlusion was decreased to an approximate 0.5 mm. anterior slide. A 1.5 mm. right lateral shift was eliminated. Measurements were made at the four central incisors. All posterior occlusal interferences were removed for the working and balanc*Denar
Corporation,
tStern
Dental
SK-err
Mfg.
Anaheim,
Company, Company,
Inc., Sybron
$Personai communication: nesota, Dec., 1972.
Calif. Mount
Vernon,
Corporation,
Dr. Kenneth
N. Y. RomuIus,
Mich.
T. AMeyer, Assistant Professor, University
of Min-
p’ll~~r3:
u
Telemetric
determination
of occlusal
contact
positions
179
ing positions. The Phase 1 switch was adjusted on the articulator without disturbing the relationship of the switch to the contactor. Then, data were collected for Phase 2. In Phase 3, all of the subject’s posterior teeth were prepared for ceramic-metal crowns on the premolars and complete cast crowns on the molars. Centric relation records were made with light posterior pressure applied by the dentist on the subject’s chin during jaw closure. The original vertical dimension of occlusion was decreased approximately 0.5 mm. at the midline to create very light contact of opposing canines in centric relation. Wherever possible, tripod&d posterior occlusion was established. Recordings in Phase 3 were obtained from a new switch which had contact only in centric relation. This was done to prevent occlusal interferences on the switch. PROCEDURES During each phase of investigation, three separate recording sessions were planned. The first session was the beginning day of each phase. The second was planned a day after the initial recordings. The third was planned a week later. Each recording session consisted of three trials. Each trial consisted of the following tasks. Before and after each trial, the dentist easily manipulated the subject’s mandible to obtain appropriate switch contact, i.e., from centric relation to centric occlusion in Phases 1 and 2, and in Phase 3, centric relation only (Fig. 2). This procedure established the clinical base line for assuming that the telemetry equipment functioned properly during each trial. That is, if the switch registered before and after each trial, contact was possible during the trial. Also, no continuous-frequency oscillation was interpreted as no burnishing of the switch plates. This meant that the occlusion was not too heavy. To demonstrate that the subject could contact the switch without assistance by the dentist, she was asked to tap rapidly five times at the beginning and at the end of each trial. Functional occlusal contacts were recorded for chewing and swallowing three types of food. These were a ~~ inch square of white bread, half of a roasted peanut, and a 1 inch length of a quartered raw carrot. Each food was chewed on the right (nontransmitter) side, the left (transmitter) side, and then whichever side the subject prefered (later determined to be the right side). Before and after chewing and swallowing each food, the subject swallowed one mouthful of water. Also included in each trial was an /s/-loaded speech task which was performed by the subject. In addition to the tria1 tasks, the subject was asked at the end of each phase of investigation to tap rapidly five times with the head in five different positions; erect and tipped up, down, left, and right. RESULTS This study was considered preliminary for three reasons. First, it attempted to assemble and use a telemetry system which had originally been employed by other investigators. 4, 6 Second, one subject was examined which made it impossible to conclude anything definitive about all patients. Third, an attempt was made to learn what to examine in the future when testing the reliability of this telemetry equipment as employed in this study. During this investigation, both laboratory and clinical difficulties arose with the telemetry equipment. For example, considerable expense was involved. A radio
180
Schorn
Table
and
I. Switch
.I. Prosthct. Frbluary.
Goodkind
contacts
per side and food type during
mastication
Peanuts
Bread
Dent. 1977
CarrorJ
LRLRLRLRLRLRLR Phase
I
Contacts Thrusts Percent contact
0 Ti? 0
IO 0 ?i 127 -% .3 0 0
10 0 2 -0 123 224 123 224 123 1.6 0 .8 0 0
1 i?i 1.2
16 198 8.1
0 ii 0
0 0 224 iii 0 0
IO 347 i-i5 .3 0
0 %ii 0
Phase 2
Contacts Thrusts Per cent contact Phme 3 lfirst four
9 72 82 198 10.9 36.4
9 i? 5.7
0 94 0
0 E 0
I I -25 94 157 146 1.1 15.9 .7
--IO 253 3.9
3 29 146 253 2.1 11.5
trials)
Contacts II 9 4 2 Thrusts 53 179 45 95 1.4 5.6 Per cent contact 7.6 6.2 13.3 9.5 Legend: L, values when food was masticated on the left side; R, values when food was masticated on the right side; CR, centric relation; CO, centric occlusion; BTW, between CR and CO. Sixteen Phase 2 slides from CO to CR were included in CR contacts, because motion stopped there. frequency-shielded room was necessary to prevent reception of commercial broadcasts. Assembly of the electronic equipment required technical advice. Magnifying optics were necessary to complete the delicate transmitter assembly and adjustment. Transmitter batteries discharged and were time-consuming to replace. Switch plates became burnished, which further delayed the study. In addition to these mechanical difficulties, scheduling problems arose. Originally, it was intended to statistically compare the three phases of investigation. This required the comparison of the sessions in each phase. Although the trials per session appeared clinically to be consistent, the data could not be statistically analyzed to conclude that the recording sessions per phase were consistent and independent. This analysis could not be applied, because many small numbers were involved, and it was impossible to conduct recording sessions as planned. For example, Phase 1 consisted of three recording sessions; and Phases 2 and 3 each had two sessions. The data obtained during these recording sessions were interpreted clinically in order to make qualitative statements only. For example, it appeared that postural position affected both the subject’s ability to contact the switch and the actual contact position on the switch. This made it important to use one head position for all recording sessions. Although the manipulated contact tasks at the beginning and end of each of the 23 experimental trials showed proper switch contact for the given phase of investigation, the unassisted taps of the subject’s teeth led to switch contact in less than 100 per cent of the taps. For example, 13 contacts were observed in centric occlusion and 14 contacts in centric relation from 90 taps before occlusal adjustment. In phase 2> 10 contacts were observed in centric occlusion and four in centric relation from 60 taps. In Phase 3, 37 contacts were observed in centric relation from 40 taps made 1
Volume Number
37 2
Fig. 3. A graphic record clusion (CO) to centric contact followed during
Telemetric
determination
of occlusal
contact
of Phase 2. Top channel shows four gliding contacts relation (CR) during mastication on the nontransmitter swallowing of food. Bottom channel shows masticatory
positions 181
from centric side. One thrusts.
ocCO
week after placement of the reconstruction. On the following day when the subject reported symptoms of a severe cold, only 30 contacts were observed in 40 taps. Taps which did not result in switch contact occurred with the mandible lateral to or forward from the line or point of possible contact being examined in each given phase of the investigation. After reconstruction, the subject apparently tapped more consistently in the stable occlusal position which had been developed. When contacts were observed during swallowing of water, no switch contacts were recorded for 36 swallows during Phase 1. In Phase 2, 17 contacts were observed in centric occlusion and three in centric relation for 31 swallows. Four contacts OCcurred as slides across the switch from centric occlusion to centric relation. Five contacts in centric relation were observed for 17 swallows of water during the first session with the restoration cemented. Considerably fewer contacts occurred in the second session of Phase 3 during deglutition and mastication than were observed during the first session. This was attributed to the subject’s sinus and nasal congestion and consequent mouth breathing. Swallowing of solid food also led to different frequencies of switch contact in the three phases of investigation. Only one contact in 81 swallows was observed in
182
Schorn
and
Goodkind
J. Prosthet. Fehnmy.
Dent. 1977
Phase 1. In Phase 2, 26 contacts were recorded in centric occlusion and three contacts in centric relation during 63 swallows. These contacts appeared to depend upon the type of food and the side on which it had been masticated. In Phase 3, an increased frequency of contact occurred in centric relation (16 contacts for 44 swallows), but this also appeared to vary with the type of food and the side of mastication. Masticatory contacts appeared to vary also with the aforementioned conditions (Table I). During 930 masticatory thrusts, after the occlusal adjustment had been completed, 16 slides were observed on the switch from centric occlusion to centric relation (Fig. 3). All slides occurred when various foods were chewed on the nontransmitter (right) side. This put the transmitter on the balancing side. The slides could have demonstrated the seating of the balancing condyle during closure in Phase 2 of the investigation. In a generalized explanation of the results, it appeared that before occlusal adjustment, the subject functioned infrequently on a line from centric relation to centric occlusion. This was attributed to the subject’s occlusal interferences. After adjustment of all deflective occlusal contacts, this subject appeared to make contact more frequently on the path from centric relation to centric occlusion. Also, most of the contact on this path was in centric occlusion. Increased contact here could have been related to a stability in this interdental position. Phase 3 contacts, which were recorded 1 week after placement of the posterior fixed restoration, seemed to indicate that the subject physiologically accepted the reconstruction and adequately functioned with it. An attempt to record contacts 1 month after placement of the fixed restoration resulted in equipment failure, which required extensive repair time. Consequently, this preliminary investigation was ended. Two additional clinical observations were made in this study. First, harder foods required more thrusts per time to masticate. Second, no switch contacts occurred in 23 repeats of an /s/-loaded speech task which was performed by the subject in the three phases of this investigation. CONCLUSIONS The completion of this three-phase telemetry investigation led to subjective clinical impressions concerning the practicality of using current telemetry equipment to study anteroposterior functional occlusal contact positions. First, the equipment that has been necessary to conduct thorough telemetry investigations has been expensive; and the method has been both time-consuming and physically difficult for experimental subjects and investigators. Second, although the method in this study was extensive, it was not sufficiently complete to offer proof that the data obtained were consistent and valid. Therefore, no description or inference beyond the individual phases of investigation for this one subject was justified. Third, telemetry equipment was considered to be subject to more investigation to eliminate the variables in its use. The elimination of these variables was considered a necessary prelude to investigation of variability in function among patients and in techniques for treating those patients.
Telemetric PRACTICAL
determination
of occlusal
contact
positions
183
SIGNIFICANCE
Previous research has been conducted with miniature intraoral telemetry equipment, and treatment procedures have been recommended from that research. The results of this study raised many questions concerning whether sound telemetric information about normal function can be obtained at this time. Without that information, treatment procedures could not be recommended. The information obtained was considered clinically useful only in the context of this study and for this subject. The authors thank Dean Erwin Schaefer for his assistance in obtaining financial support for this study. Also, the authors thank Dr. Irving Glickman, who agreed to permit the use of his transmitter, and Mr. Fred Roeber, who showed the authors how to assemble their telemetry system. Finally, the assistance provided by Mr. Robert Borher in developing a receiver and recording system is greatly appreciated.
References 1.
Adams, S. H., and Zander, H. A.: Functional Tooth Contacts in Lateral and in Centric Occlusion, J. Am. Dent. Assoc. 69: 465-473, 1964. 2. Anderson, D. J., and Picton, D. C.: Tooth Contact During Chewing, J, Dent. Res. 36: 21-26, 1957. 3. Brewer, A. A., and Hudson, D. D.: Application of Miniaturized Electronic Devices to the Study of Tooth Contacts in Complete Dentures, J. PROSTHET. DENT. 11: 62-72, 1961. 4. Brion, M., Pameijer, J. H., Glickman, I., and Roeber, F.: Recent Intraoral Telemetry Findings and Their Development in the Study of Occlusion, Int. Dent. J. 19: 541-552, 1969. 5. Butler, J. A., and Zander, H. A.: Evaluation of Two Occlusal Concepts, Parodont. Acad. Rev. 2: 5-18, 1968. 6. Glickman, I., Haddad, A., Mart&non, M., Mehta, N., Roeber, F., and Clark, E.: Telemetric Comparison of Centric Relation and Centric Occlusion Reconstructions, J. PROSTHET. DENT. 31: 527-536, 1974. 7. Goodkind, R. J., Butler, J. A., and Schulte, R. C.: Tooth Contact Relationships Revealed by Intraoral Telemetry (A Preliminary Report), Northwest Dent. 49: 362-366, 1970. 8. Roeber, F., Pameijer, J. H., and Glickman, I.: An Intraoral Electronic System for the Study of Dental Occlusion, Med. Biol. Eng. 5: 677-679, 1968. 9. Jankelson, B., Hoffman, G. M., and Hendron, J. A.: The Physiology of the Stomatognathic System, J. Am. Dent. Assoc. 46: 375-386, 1953. UNIVERSITY
SCHOOL MINNEAPOLIS,
OF MINNESOTA OF DENTISTRY MINN.
55455
fundimd report
James A. Schorn, D.D.S., M.S.D.,* and Richard J. Goodkind, D.M.D., University of Minnesota, School of Dentistry, Minneapolis, Minn.
M.S.**
A
fter many years of research on centric relation and acquired occlusal positions (centric occlusion), a divergence of opinion still exists concerning the anteroposterior functional occlusal contact position. 1-8 This divergence has led to much controversy and to many discussions regarding restoration for the prosthodontic patient. The need to acquire knowledge to aid in the solution of this controversy was the reason for this study. For dentists, “. . . the maintenance and restoration of normal physiology of the stomatognathic system can best be achieved if procedures are based on knowledge of normal function.“9 To acquire this knowledge, scientific methodology must be applied to research. Part of this methodology requires investigative tools which deliver statistically reliable and valid information about subject or investigator variables under examination. Intraoral telemetry is one tool which has been utilized in research on occlusion. Relatively little information has been received concerning the anteroposterior functional occlusal contact position. Most of this information has not been reliable enough to make definitive statements about normal function in all patients. It was the purpose of this study to report information received from miniature intraoral telemetry equipment employed to examine anteroposterior functional occlusal contact positions. With more information available to dentists, perhaps they can better understand normal function and, consequently, prescribe modes of treatment. METHOD Three phases of investigation+ a mildly symptomatic mandibular This article is a summary of Master of Science from the University Read
before
*Assistant
**Professor tPersona1 May, 1972.
176
the American Professor, and
Director
a thesis presented of Minnesota.
Prosthodontic
Division
communication:
were conducted on one subject who demonstrated shift from centric relation to centric occlusion. In
Society,
in
partial
Chicago,
fulfillment
of
the
degree
Ill.
of Prosthodontics.
of Graduate Dr.
James
Prosthodontics. Butler,
Associate
Professor,
University
of Minnesota,
of
Telemetric
determination
Fig.
components
1. The
of occlusal
of the
contact positions 177
transmitter.
the first phase, occlusal-point contact on a line from centric relation to centric occlusion was examined on the subject’s unaltered occlusal scheme. This was done by inserting a removable telemetry transmitter* pontic into two fixed crowns which duplicated the subject’s original anatomy. In Phase 2, a complete occlusal adjustment was performed. Contact on the original transmitter switch was then recorded to be compared with Phase 1 data. In the final phase of investigation, a complete posterior reconstruction was prepared with centric occlusion coincident with centric relation. In addition, light anterior tooth contact on the subject’s canines was provided when the posterior crowns occluded. A new transmitter was fabricated and used to record centric relation contact during mastication and deglutition. EQUIPMENT This study utilized a transmitter and receiving antenna like those used by Roeber and associates8 The transmitter consisted of a battery, a multilayered switch, and an oscillator which broadcasts on three frequencies (Fig. 1). These multiple frequencies allowed alignment of the switch to determine anteroposterior contacts on a line from centric relation (one frequency) to centric occlusion (a different frequency). The receivers used were similar to those used by Roeber and associates.8 However, the recording apparatus differed. A two-channel, 60 cycle oscillograph was used. An amplifier was made to discriminate the three possible transmitter frequencies on one oscillograph channel.* This was accomplished by causing a different amplitude of stylus deflection for each frequency. The second oscillograph channel was used to *Personal communication: Minnesota, Minneapolis, Minn.,
Mr. Robert Oct., 1972.
Borher,
Department
of Biophysics,
University
of
178
Schorn
and
J. Prosthet. February,
Goodkind
Dent. 1971
Fig. 2. A graphic record of Phase 1. At the right are the three possible frequencies on a path during jaw manipulation. Greatest deflection was centric relation, and the least deflection was centric occlusion. At the far left is an illustration of cross over between frequencies (an electronic complication which was easily detected when it occurred on the records). manually record chewing strokes. A timer-marker was used to manually record swallowing episodes. Phase 1 began with mounting of diagnostic casts and verifying of all records on a completely adjustable articulator (D5AF) .+ Zinc oxide/eugenol paste was used to make an interocclusal record with the teeth in centric occlusion. The lower left second molar and left second premolar were prepared for complete crowns. Cast gold retainers, which duplicated the original occlusal scheme, were fabricated from patterns formed by painting acrylic resin into the previously fabricated occlusal index. Stern’s 0.096 inch precision attachments? were inserted into the retainers to hold a removable transmitter pontic which replaced the lower left first molar. The upper left first molar was prepared for a complete cast coping from which a switch contactor (No. 80 Endopostt) was extended to represent a mesiolingual cusp tip. Accuracy of the duplication procedure was checked by comparing preoperative and postinsertion verification records. A Vericheck* instrument was used for this procedure. Before the transmitter was completely assembled for placement in the mouth of the subject, the switch was ground into occlusion. This was done on the articulator. A dull, pointed incisal pin cast from type III gold alloy was used to customize an acrylic resin incisal guide table. A turbine handpiece, with a No. j/2 round bur placed in the position of the switch contactor, was fastened to the upper member of the articulator-.$ The switch was ground in, and working casts were occluded. The transmitter was then assembled and bench tested before completing Phase 1 with the subject. In Phase 2, a complete occlusal adjustment was performed on the subject’s dentition. An approximate 3 mm. forward and upward slide from centric relation to centric occlusion was decreased to an approximate 0.5 mm. anterior slide. A 1.5 mm. right lateral shift was eliminated. Measurements were made at the four central incisors. All posterior occlusal interferences were removed for the working and balanc*Denar
Corporation,
tStern
Dental
SK-err
Mfg.
Anaheim,
Company, Company,
Inc., Sybron
$Personai communication: nesota, Dec., 1972.
Calif. Mount
Vernon,
Corporation,
Dr. Kenneth
N. Y. RomuIus,
Mich.
T. AMeyer, Assistant Professor, University
of Min-
p’ll~~r3:
u
Telemetric
determination
of occlusal
contact
positions
179
ing positions. The Phase 1 switch was adjusted on the articulator without disturbing the relationship of the switch to the contactor. Then, data were collected for Phase 2. In Phase 3, all of the subject’s posterior teeth were prepared for ceramic-metal crowns on the premolars and complete cast crowns on the molars. Centric relation records were made with light posterior pressure applied by the dentist on the subject’s chin during jaw closure. The original vertical dimension of occlusion was decreased approximately 0.5 mm. at the midline to create very light contact of opposing canines in centric relation. Wherever possible, tripod&d posterior occlusion was established. Recordings in Phase 3 were obtained from a new switch which had contact only in centric relation. This was done to prevent occlusal interferences on the switch. PROCEDURES During each phase of investigation, three separate recording sessions were planned. The first session was the beginning day of each phase. The second was planned a day after the initial recordings. The third was planned a week later. Each recording session consisted of three trials. Each trial consisted of the following tasks. Before and after each trial, the dentist easily manipulated the subject’s mandible to obtain appropriate switch contact, i.e., from centric relation to centric occlusion in Phases 1 and 2, and in Phase 3, centric relation only (Fig. 2). This procedure established the clinical base line for assuming that the telemetry equipment functioned properly during each trial. That is, if the switch registered before and after each trial, contact was possible during the trial. Also, no continuous-frequency oscillation was interpreted as no burnishing of the switch plates. This meant that the occlusion was not too heavy. To demonstrate that the subject could contact the switch without assistance by the dentist, she was asked to tap rapidly five times at the beginning and at the end of each trial. Functional occlusal contacts were recorded for chewing and swallowing three types of food. These were a ~~ inch square of white bread, half of a roasted peanut, and a 1 inch length of a quartered raw carrot. Each food was chewed on the right (nontransmitter) side, the left (transmitter) side, and then whichever side the subject prefered (later determined to be the right side). Before and after chewing and swallowing each food, the subject swallowed one mouthful of water. Also included in each trial was an /s/-loaded speech task which was performed by the subject. In addition to the tria1 tasks, the subject was asked at the end of each phase of investigation to tap rapidly five times with the head in five different positions; erect and tipped up, down, left, and right. RESULTS This study was considered preliminary for three reasons. First, it attempted to assemble and use a telemetry system which had originally been employed by other investigators. 4, 6 Second, one subject was examined which made it impossible to conclude anything definitive about all patients. Third, an attempt was made to learn what to examine in the future when testing the reliability of this telemetry equipment as employed in this study. During this investigation, both laboratory and clinical difficulties arose with the telemetry equipment. For example, considerable expense was involved. A radio
180
Schorn
Table
and
I. Switch
.I. Prosthct. Frbluary.
Goodkind
contacts
per side and food type during
mastication
Peanuts
Bread
Dent. 1977
CarrorJ
LRLRLRLRLRLRLR Phase
I
Contacts Thrusts Percent contact
0 Ti? 0
IO 0 ?i 127 -% .3 0 0
10 0 2 -0 123 224 123 224 123 1.6 0 .8 0 0
1 i?i 1.2
16 198 8.1
0 ii 0
0 0 224 iii 0 0
IO 347 i-i5 .3 0
0 %ii 0
Phase 2
Contacts Thrusts Per cent contact Phme 3 lfirst four
9 72 82 198 10.9 36.4
9 i? 5.7
0 94 0
0 E 0
I I -25 94 157 146 1.1 15.9 .7
--IO 253 3.9
3 29 146 253 2.1 11.5
trials)
Contacts II 9 4 2 Thrusts 53 179 45 95 1.4 5.6 Per cent contact 7.6 6.2 13.3 9.5 Legend: L, values when food was masticated on the left side; R, values when food was masticated on the right side; CR, centric relation; CO, centric occlusion; BTW, between CR and CO. Sixteen Phase 2 slides from CO to CR were included in CR contacts, because motion stopped there. frequency-shielded room was necessary to prevent reception of commercial broadcasts. Assembly of the electronic equipment required technical advice. Magnifying optics were necessary to complete the delicate transmitter assembly and adjustment. Transmitter batteries discharged and were time-consuming to replace. Switch plates became burnished, which further delayed the study. In addition to these mechanical difficulties, scheduling problems arose. Originally, it was intended to statistically compare the three phases of investigation. This required the comparison of the sessions in each phase. Although the trials per session appeared clinically to be consistent, the data could not be statistically analyzed to conclude that the recording sessions per phase were consistent and independent. This analysis could not be applied, because many small numbers were involved, and it was impossible to conduct recording sessions as planned. For example, Phase 1 consisted of three recording sessions; and Phases 2 and 3 each had two sessions. The data obtained during these recording sessions were interpreted clinically in order to make qualitative statements only. For example, it appeared that postural position affected both the subject’s ability to contact the switch and the actual contact position on the switch. This made it important to use one head position for all recording sessions. Although the manipulated contact tasks at the beginning and end of each of the 23 experimental trials showed proper switch contact for the given phase of investigation, the unassisted taps of the subject’s teeth led to switch contact in less than 100 per cent of the taps. For example, 13 contacts were observed in centric occlusion and 14 contacts in centric relation from 90 taps before occlusal adjustment. In phase 2> 10 contacts were observed in centric occlusion and four in centric relation from 60 taps. In Phase 3, 37 contacts were observed in centric relation from 40 taps made 1
Volume Number
37 2
Fig. 3. A graphic record clusion (CO) to centric contact followed during
Telemetric
determination
of occlusal
contact
of Phase 2. Top channel shows four gliding contacts relation (CR) during mastication on the nontransmitter swallowing of food. Bottom channel shows masticatory
positions 181
from centric side. One thrusts.
ocCO
week after placement of the reconstruction. On the following day when the subject reported symptoms of a severe cold, only 30 contacts were observed in 40 taps. Taps which did not result in switch contact occurred with the mandible lateral to or forward from the line or point of possible contact being examined in each given phase of the investigation. After reconstruction, the subject apparently tapped more consistently in the stable occlusal position which had been developed. When contacts were observed during swallowing of water, no switch contacts were recorded for 36 swallows during Phase 1. In Phase 2, 17 contacts were observed in centric occlusion and three in centric relation for 31 swallows. Four contacts OCcurred as slides across the switch from centric occlusion to centric relation. Five contacts in centric relation were observed for 17 swallows of water during the first session with the restoration cemented. Considerably fewer contacts occurred in the second session of Phase 3 during deglutition and mastication than were observed during the first session. This was attributed to the subject’s sinus and nasal congestion and consequent mouth breathing. Swallowing of solid food also led to different frequencies of switch contact in the three phases of investigation. Only one contact in 81 swallows was observed in
182
Schorn
and
Goodkind
J. Prosthet. Fehnmy.
Dent. 1977
Phase 1. In Phase 2, 26 contacts were recorded in centric occlusion and three contacts in centric relation during 63 swallows. These contacts appeared to depend upon the type of food and the side on which it had been masticated. In Phase 3, an increased frequency of contact occurred in centric relation (16 contacts for 44 swallows), but this also appeared to vary with the type of food and the side of mastication. Masticatory contacts appeared to vary also with the aforementioned conditions (Table I). During 930 masticatory thrusts, after the occlusal adjustment had been completed, 16 slides were observed on the switch from centric occlusion to centric relation (Fig. 3). All slides occurred when various foods were chewed on the nontransmitter (right) side. This put the transmitter on the balancing side. The slides could have demonstrated the seating of the balancing condyle during closure in Phase 2 of the investigation. In a generalized explanation of the results, it appeared that before occlusal adjustment, the subject functioned infrequently on a line from centric relation to centric occlusion. This was attributed to the subject’s occlusal interferences. After adjustment of all deflective occlusal contacts, this subject appeared to make contact more frequently on the path from centric relation to centric occlusion. Also, most of the contact on this path was in centric occlusion. Increased contact here could have been related to a stability in this interdental position. Phase 3 contacts, which were recorded 1 week after placement of the posterior fixed restoration, seemed to indicate that the subject physiologically accepted the reconstruction and adequately functioned with it. An attempt to record contacts 1 month after placement of the fixed restoration resulted in equipment failure, which required extensive repair time. Consequently, this preliminary investigation was ended. Two additional clinical observations were made in this study. First, harder foods required more thrusts per time to masticate. Second, no switch contacts occurred in 23 repeats of an /s/-loaded speech task which was performed by the subject in the three phases of this investigation. CONCLUSIONS The completion of this three-phase telemetry investigation led to subjective clinical impressions concerning the practicality of using current telemetry equipment to study anteroposterior functional occlusal contact positions. First, the equipment that has been necessary to conduct thorough telemetry investigations has been expensive; and the method has been both time-consuming and physically difficult for experimental subjects and investigators. Second, although the method in this study was extensive, it was not sufficiently complete to offer proof that the data obtained were consistent and valid. Therefore, no description or inference beyond the individual phases of investigation for this one subject was justified. Third, telemetry equipment was considered to be subject to more investigation to eliminate the variables in its use. The elimination of these variables was considered a necessary prelude to investigation of variability in function among patients and in techniques for treating those patients.
Telemetric PRACTICAL
determination
of occlusal
contact
positions
183
SIGNIFICANCE
Previous research has been conducted with miniature intraoral telemetry equipment, and treatment procedures have been recommended from that research. The results of this study raised many questions concerning whether sound telemetric information about normal function can be obtained at this time. Without that information, treatment procedures could not be recommended. The information obtained was considered clinically useful only in the context of this study and for this subject. The authors thank Dean Erwin Schaefer for his assistance in obtaining financial support for this study. Also, the authors thank Dr. Irving Glickman, who agreed to permit the use of his transmitter, and Mr. Fred Roeber, who showed the authors how to assemble their telemetry system. Finally, the assistance provided by Mr. Robert Borher in developing a receiver and recording system is greatly appreciated.
References 1.
Adams, S. H., and Zander, H. A.: Functional Tooth Contacts in Lateral and in Centric Occlusion, J. Am. Dent. Assoc. 69: 465-473, 1964. 2. Anderson, D. J., and Picton, D. C.: Tooth Contact During Chewing, J, Dent. Res. 36: 21-26, 1957. 3. Brewer, A. A., and Hudson, D. D.: Application of Miniaturized Electronic Devices to the Study of Tooth Contacts in Complete Dentures, J. PROSTHET. DENT. 11: 62-72, 1961. 4. Brion, M., Pameijer, J. H., Glickman, I., and Roeber, F.: Recent Intraoral Telemetry Findings and Their Development in the Study of Occlusion, Int. Dent. J. 19: 541-552, 1969. 5. Butler, J. A., and Zander, H. A.: Evaluation of Two Occlusal Concepts, Parodont. Acad. Rev. 2: 5-18, 1968. 6. Glickman, I., Haddad, A., Mart&non, M., Mehta, N., Roeber, F., and Clark, E.: Telemetric Comparison of Centric Relation and Centric Occlusion Reconstructions, J. PROSTHET. DENT. 31: 527-536, 1974. 7. Goodkind, R. J., Butler, J. A., and Schulte, R. C.: Tooth Contact Relationships Revealed by Intraoral Telemetry (A Preliminary Report), Northwest Dent. 49: 362-366, 1970. 8. Roeber, F., Pameijer, J. H., and Glickman, I.: An Intraoral Electronic System for the Study of Dental Occlusion, Med. Biol. Eng. 5: 677-679, 1968. 9. Jankelson, B., Hoffman, G. M., and Hendron, J. A.: The Physiology of the Stomatognathic System, J. Am. Dent. Assoc. 46: 375-386, 1953. UNIVERSITY
SCHOOL MINNEAPOLIS,
OF MINNESOTA OF DENTISTRY MINN.
55455