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Influence of occlusal splints on jaw position and musculature in patients with temporomandibular joint dysfunction
Temporomandibular joint i
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Influence of occlusal splints on jaw position and musculature in patients with temporomandibular joint dysfunction W. C. Kovaleski, I!1, D.D.S., M.S.,* and J. De Boever, L.D.S., D.M.D.** The University o/Michigan, School o/ Dentistry, Ann Arbor, Mich.
Even though the effect of the therapy is only partially understood and is sometimes equivocal, occlusal splints have been used extensively in the treatment of patients with functional disturbances of the temporomandibular joints. ~-; The effectivehess of splints has been related to tim avoidance of the disturbing input of oeclusal interferences o n the neuromuscular mechanism of the masticatory system."" ~ The purpose of this study was to investigate the influence of an occlusal bite plane splint on jaw position and relief of functional temporomandibular joint ( T M J ) and muscle symptoms.
MATERIALS AND METHOD Eleven patients (two male and nine female), between 14 and 35 ),ears of age, with functional disturbances of one or both joints were studied. The symptoms existed from five months to I0 ),ears. None of the patients had been treated before with any typ'c of occlusal splint. None of them had either removable complete or partial dentures. There was no control group. The occlusal splint. The full-coverage splint" was constructed in heat-cured clear acrylic resin and adjusted in the mouth to eliminate occlusal interferences. The splint was made with simultaneous contact of the lower supporting cusps and the incisal edges in the centric jaw relation. The surface was smooth to allow free movement in all directions. A cuspid rise was placed in the splint to assure freedom for lateral and protrusive excursions. In order to achieve the most accurate measurements of the movement of the lower incisors on the splint, three permanent bench marks were made in the splint: Points A and B were made in the splint in the molar area, and point C was made in the incisor area. The point C was determined by placing the patients' jaws in centric *Assistant Professor, Department of Occlusion, University of Michigan. **Associate Professor, Crown and Bridge Department, University of Ghent.
321
322
Kovaleski and De Boever
j. Prosthet. Dent. March, 1975
T a b l e I. Summary of analysis of variance results: N u m b e r of silent periods during
tapping Without splint Time
Mean II
2 3 4 2, 3, 4*
With splint
J
Time Ill
10.90 10.30 9.70 10.30
P
I
-- m
MS
F
a/
p
120.05 45.00 39.20 190.82
20.71 6.23 3.84 14.47
1.9 1.9 1.9 1.9
< 0.01 < 0.05 NS < 0.01
Mean - -
2 3 4 9 3, 4*
I
I
6.00 7.30 6.90 6.73
I
~Mean of three sessions.
relation for that day. With the teeth contacting the splint in this position, the point between the l o w e r central incisors was located on tile splint with a pointed stylus immediately after delivery. The point was permanently marked on the splint. In order to avoid prejudgment on the relocation of point C in future measurements, the anterior area was masked with 28 gauge green wax prior to relocation. T h e new point was permanently marked on the splint. T h e measurements from A to B, B to C, and A to C were made with a sharpened Boley gauge and recorded. T h e measurements were used to construct triangles according to the geometric principles of triangulation. T h e change in position was resolved on the X and Y axes to allow the construction of a line representing the mean amount of movement. T h e mean of the sum of anterolateral movement and the mean for the sum of posterolateral movement were calculated after 72 hours and after one month. Electromyography. Platinum hook electrodes, as described by Ahlgren, TM were used to record the electrical activity in the masseter, anterior temporal, posterior temporal, and suprahyoid muscles. A standardized method for placement of the electrodes was used. T h e potentials were recorded on a polygraph * at a paper speed of 50 ram. pet" second and on analogue taper for replay with time expansion. T h e channels of the polygraph were calibrated at 50 ttv. Potentials were recorded during rest position, swallowing, chewing of paraffin, lateral aiad protrusive excursions with the teeth in contact, exertion of Iioht and heavy forces, and tapping of the teeth in centric occlusion. T h e same procedure, except for chewing, was used with and without the occlusal splint. In six of the 11 patients, a jaw jerk reflex was produced during maximal voluntary clenchin/ in centric occlusion by tapping on the chin with a reflex ham1! l e r .
SUMMATION OF TREATMENT SEQUENCE 7"ime 1: Initial examination 7"ime 2: First treatment visit a. EMG without bite plane splint b~ Deliver bite plane splint c. Mark position of lower incisors on splint with mandible in eentric jaw relation d. EMG with bite plane splint in mouth ~Polygraph model 75, Grass Instrument Company, Quincy, Mass. t F M tape recorder 3955, Hewlett Packard, Palo Alto, Calif.
Occlusal splints and T M ] dys/unction
V,,lm,,,. :~:~ N v m b e r :~
323
Time 3: Second treatment visit (at 72 hours) a. Mark position of lower incisors on splint with mandible in eentric jaw relation b. Adjust any interference on splint c. EMG with splint in mouth d. EMG without splint in mouth
Time 4: Third treatment visit (at one month) a. b. e. d.
Mark position of lower incisors with mandible in eentric jaw relation Adjust any interferences EMG with splint in mouth EMG without splint in mouth
EVALUATION OF THE EMG T h e E M G evaluation was done by visual examination of the tracings for asynchronous nmscle activity. A determination was made of the asynchronous activity of the muscles at rest at the beginning, the middle, and the end of the session, and an examination was made of the swallowing pattern, gliding movements, and coordination and synchronization of chewing pattern. T h e recordings of the right masseter muscle during 15 tappings in eentric occlusion with and without the spliltt were replayed with time expansion, the "silent periods" were counted, and their duration was measured. T h e recordings of the other muscles were also replayed, but the silent periods were not measured. The E M G of tlle masseter nmscles during clenching was replayed, and the silent period after the jaw jerk reflex was measured.
STATISTICAL ANALYSIS An analysis of variance was used to test the null hypothesis when comparing: the mean duration of silent periods with and without the occlusal bite plane splint, the mean n u m b e r of silent periods with 'find without the occlusal splint, and the mean duration of silent periods after the jaw jerk reflex at three specific times. A threefactor completely crossed design was used.
RESULTS T h e direction of the m o v e m e n t of the mandible on the splint after 72 hours was most often toward the painful side and anteriorly directed. After 72 hours, six patients moved to the side of the painful joint, one to the opposite side, and one did not move. Of the three patients with pain in both joints, one moved straight forward, and two moved laterally and anteriorly. After one month, the mandibles of five patients stayed in the same position, as after 72 hours. In four patients, the mandibles lnoved a little more in the same direction. The patient who moved to the opposite side after 72 hours had moved to the side of the painful joint after one month. O n e patient moved back to the starting position. T h e extent of the m a n d i b u l a r m o v e m e n t varied from patient to patient and from one session to another, but never exceeded 3.5 + 1.0 ram. After .72 hours, for nine patients, there was a mean anterolateral movement of 1.82 +_ 0.93 ram. T w o patients had a posterolateral mean lnovement of 2.6 + 1.8 ram. After one ntonth, for 10 patients, there was a mean anterolateral movement of 1.78 _+ 0.97 ram. One patient had a posterolateral mean movement of 1.7 ram.
324
Kovaleski and De Boever
J. Prosthet. Dent. March, 1975 II
R. ANT. T E M P O R A L
L.
ANT.
TEMPORAL
R. •P O S T .
TEMPORAL
L. POST.
TEMPORAL
DIGASTRIC
.
.11 9
Fig. 1. With (II) and without (I) splint. Calibration is 50 #v. and 1.second. Table II. Summary of analysis of variance results" Comparison of mean duration of silent period during tapping with splint and without splint Without splint
With splint Mean
MS
Time
(msec.)
2 3 4 2, 3, 4*
23.35 21.67 22.68 22.57
(msgr.) 14.663 1.815 1.815 4.888
,Mean Time •
,
|
2 3 4 2, 3, 4*
(reset.) 21.64 22.27 22.08 21.99
F
d/
p
0.85 0.41 1.33 0.65
1.9 1.9 1.9 1.9
NS NS NS NS
~'Mean of t h r e e sessions.
With respect to symptoms, nine of 11 patients reported pain a n d / o r clicking relieved after 72 hours. All the patients were followed up to two months after the third treatment visit, and the occlusal adjustment was performed according to the technique advocated by Ramfjord and Ashy They all remained symptom free during a six-month follow-up. The silent periods in i5 voluntary taps in centric occlusionare summarized in Table I. The duration of these silent periods was measured, and the results are summarized in Table II. The initial E M G trace usually showed hyperactivity in the right or left posterior temporal muscle. The immediate response of the muscles was a decrease in the E M G activity at rest in six of the subjects. On the other hand, there was an increase in the activity of the suprahyoid muscles in nine patients whenever the splint was in
Occlusal splints and TMJ dysfunction
voh.n~.~3 Number 3
III
325
IV
R. ANT. TEMPORAL
L.
ANT.
R. P O S T .
TEMPORAL
'. . . .
TEMPORAL
go,. - ~ - , - ¢ - - , : : i ' ¢ - - ~ - ~ - , ~
L. POST. T E M P O R A L
DIGASTRIC
illl
Fig. 2. With (III) and without (IV) splint. the mouth. This was immediately reduced when the splint was removed. Typical rest position tracings are shown in Figs. 1 to 3 ~ T i m e s 2, 3, and 4, respectively. DISCUSSION
Although it was previously felt that the mandible was moving posteriorly as the symptoms disappeared, the measurement of the phenomenon does not agree with this concept. The duration of the silent periods with jaw jerk did decrease to within a normal range after one month for all subjects. In none of the patients were the silent periods totally absent, but in three patients, the silent period was not present in one to three of the nine jaw jerks elicited in each session. These patients did not show the most severe clinical symptoms. The number of silent periods in tapping with the splint decreased compared to n u m b e r without the splint (Table I). This decrease was significant (P < 0.05). This suggests a decreased influence of the occlusion on the musculature with the occlusal splint in the mouth. The duration of the silent periods for tapping stayed the same whether or not the splint was in place (Table II). Although the duration of the silent period was slightly longer than reported previously by others (15.3 msec./'~ 10 to 20 msec./~' 8 to 20 msec., ~; and 13 msec.~S), the difference is probably related to the method of measurement and method of tapping. T h e hyperactivity in the posterior part of the temporal muscle has been interpreted as a "splinting action" caused by an attempt to hold the condyle away from the painful areas, ~ and that hyperactivity was mostly on the painful side. In this study, a tendency to hyperactivity on the opposite side was observed. In most of
326
Kovaleski and De Boever
J. l'rosthet. Dent. March, 1975
V
VI
R. ANT. TF2dPC3RA[,
L. ANT.
TEMPORAL
R. POST. T E M P O R A L
L. POST. TEMPORAL
DIGASTRIC
_
..
.
.
.
,
| J
Fig. 3. With (V) and without (VI) splint. the patients, the relaxation of the involved posterior temporal muscles resulted in a movement of the mandible on the occlusal splint toward the involved side. In the patients with both muscles involved, the mandible tended to move straight forward. Only one of the patients moved the mandible distalIy on the occlusal splint after one month. CONCLUSIONS After the use of an occlusal bite plane splint for one month: (1) the mandible moves anteriorly and laterally on an occlt,sal bite' plane splint where there is sufficient centric freedom built into the splint; (2) there is a decrease in TMJ-muscle symptoms provided anterior mandibular movement is not trapped by occlusal interferences, cuspid guidance, a n d / o r incisal guidance on the splint; and (3) there is a decrease in the number of silent periods elicited during tapping with the occlusal splint in the mouth. References I. Granger, E. R.: Occh,sion in Temporonlandibular Joint Pain, J. Am. Dent. Assoc. 56: 659-664, 1958. 2. Hupfauf, L., and Weitkamp, J.: Ergebnisse der Behandlung von funktionsbedingten Erkrankungen des Kausystems mit Aufbissplatten, Dtsch. Zahnaerztl. Z. 24: 347-351, 1969. Kanter, t'.: The Use of Bite Plates, in Schwartz, L., editor: Disorders of the Temporomandibular Joint, Philadelphla, 1959, W. B. Saunders Company, pp. 300-306. 4. Posseh, U.: Physiology of Occlusion and Rehabilitation, Philadelphia, 1962, F. A. Davis Company. 5. Posseh, U.: Treatment of Bruxism by Bite Guards and Bite Plates, J. Can. Dent. Assoc. 29: 77q-779, 1963. ,
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Volume 33 Number 3
OccIusal splints and TAll] dysfunction 327
6. Ramfjord, S. P., and Ash, M. M.: Occlusion, ed. 2, Philadelphia, 1971, W. B. Saunders Company. 7. Zarb, G. A., and Thompson, G. W.: Assessment of Clinical Treatment of Patients With Temporomandibular Joint Dysfunction, J. PROSTnET. DENT. 24: 542-554, 1970. 8. Perry, H. T.: Muscular Changes Associated With Temporomandibular Joint Dysfunction, J. Am. Dent. Assoc. 54: 644-653, 1957. 9. Ramfjord, S. P.: Dysfunctional, Temporomandibular Joint and Muscle Pain, J. PROST~IET. DENT. 11: 353-374, 1961. 10. Ahlgren, J.: An Intercutaneous Needle Electrode for Kinesiologic EMG Studies, Acta Odontol. Scand. 25:15-I9, 1967. 11. Jarabak, J. R.: Electromyographic Analysis of Muscular and Temporomandibular Joint Disturbances Due to Imbalances of Occlusion, Angle Orthod. 24: 170.190, 1956. 12. Lous, I., Sheik-OI-Eslam, A., and Moller, E.: Postural Activity in Subjects With Functional,Disorders of the Chewing Apparatus, Scand. J. Dent. Res. 78: 404-410, 1970. 13. Yemm, R.: Temporomandibular Dysfunction and Masseter Muscle Response to Experimental Stress, Br. Dent. J. 127: 508-510, 1969. 14. Schulte, W.: Zur funktionellern Behandlung der Myo-arthropathien des Kauorganes: Ein diagnostisches und physio-therapeutisches Programm, Dtsch. Zahnaerztl. Z. 25: 422-436, 1970. 15. Ahlgren,'J.: The Silent Period in the EMG of the Jaw Muscles During Mastication and Its Relationship to Tooth Contact, Acta Odontol. Scand. 27: 219-227, 1969. 16. Hannam, A. G., Matthews, B., and Yemm, P.: Changes in the Activity of the Masseter Muscle Following Tooth Contact in Man, Arch. Oral Biol. 14: 1401-1406, 1969. 17. Matthews, B., and Yemm, R. : A Silent Period in the Masseter Eleetromyogram Following Tooth Contact in Subjects Wearing Full Dentures, Arch. Oral Biol. 15: 531-535, 1970. 18. Griffin, C. J., and Munro, R. R. : Electromyography of Jaw Closing Muscles in the OpenClose-Clench in Man, Arch. Oral Biol. 14: 141-149, 1969. 19. Besette, R., Bishop, B., and Mohl, N.: Duration of Masseteric Period in Patients With TMJ-Syndrome, Int. Assoc. Dent. Res. Abst. No. 406, March, 1971. 20. Griffin, C. J., and Munro, R. R.: Electromyography of the Masseter and Anterior Temporalis Muscles in Patient With Temporomandibular Dysfunction, Arch. Oral Biol. 16: 929-949, 1971. DR. KOVALESKI ]DEPARTMENT OF OCCLUSION SCHOOL OF DENTISTRY THE UNIVERSITY OF MICHIGAN
AN,~ ARBOR, MICH. 42104 DR. DE BOEVER UNIVERSITY OF GHENT DIENST PROTHETODONTIE AKADEMISCH ZIEKENHUIS bE PINTELAAN, 135 B-9000 CHANT, BELGIUM
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Influence of occlusal splints on jaw position and musculature in patients with temporomandibular joint dysfunction W. C. Kovaleski, I!1, D.D.S., M.S.,* and J. De Boever, L.D.S., D.M.D.** The University o/Michigan, School o/ Dentistry, Ann Arbor, Mich.
Even though the effect of the therapy is only partially understood and is sometimes equivocal, occlusal splints have been used extensively in the treatment of patients with functional disturbances of the temporomandibular joints. ~-; The effectivehess of splints has been related to tim avoidance of the disturbing input of oeclusal interferences o n the neuromuscular mechanism of the masticatory system."" ~ The purpose of this study was to investigate the influence of an occlusal bite plane splint on jaw position and relief of functional temporomandibular joint ( T M J ) and muscle symptoms.
MATERIALS AND METHOD Eleven patients (two male and nine female), between 14 and 35 ),ears of age, with functional disturbances of one or both joints were studied. The symptoms existed from five months to I0 ),ears. None of the patients had been treated before with any typ'c of occlusal splint. None of them had either removable complete or partial dentures. There was no control group. The occlusal splint. The full-coverage splint" was constructed in heat-cured clear acrylic resin and adjusted in the mouth to eliminate occlusal interferences. The splint was made with simultaneous contact of the lower supporting cusps and the incisal edges in the centric jaw relation. The surface was smooth to allow free movement in all directions. A cuspid rise was placed in the splint to assure freedom for lateral and protrusive excursions. In order to achieve the most accurate measurements of the movement of the lower incisors on the splint, three permanent bench marks were made in the splint: Points A and B were made in the splint in the molar area, and point C was made in the incisor area. The point C was determined by placing the patients' jaws in centric *Assistant Professor, Department of Occlusion, University of Michigan. **Associate Professor, Crown and Bridge Department, University of Ghent.
321
322
Kovaleski and De Boever
j. Prosthet. Dent. March, 1975
T a b l e I. Summary of analysis of variance results: N u m b e r of silent periods during
tapping Without splint Time
Mean II
2 3 4 2, 3, 4*
With splint
J
Time Ill
10.90 10.30 9.70 10.30
P
I
-- m
MS
F
a/
p
120.05 45.00 39.20 190.82
20.71 6.23 3.84 14.47
1.9 1.9 1.9 1.9
< 0.01 < 0.05 NS < 0.01
Mean - -
2 3 4 9 3, 4*
I
I
6.00 7.30 6.90 6.73
I
~Mean of three sessions.
relation for that day. With the teeth contacting the splint in this position, the point between the l o w e r central incisors was located on tile splint with a pointed stylus immediately after delivery. The point was permanently marked on the splint. In order to avoid prejudgment on the relocation of point C in future measurements, the anterior area was masked with 28 gauge green wax prior to relocation. T h e new point was permanently marked on the splint. T h e measurements from A to B, B to C, and A to C were made with a sharpened Boley gauge and recorded. T h e measurements were used to construct triangles according to the geometric principles of triangulation. T h e change in position was resolved on the X and Y axes to allow the construction of a line representing the mean amount of movement. T h e mean of the sum of anterolateral movement and the mean for the sum of posterolateral movement were calculated after 72 hours and after one month. Electromyography. Platinum hook electrodes, as described by Ahlgren, TM were used to record the electrical activity in the masseter, anterior temporal, posterior temporal, and suprahyoid muscles. A standardized method for placement of the electrodes was used. T h e potentials were recorded on a polygraph * at a paper speed of 50 ram. pet" second and on analogue taper for replay with time expansion. T h e channels of the polygraph were calibrated at 50 ttv. Potentials were recorded during rest position, swallowing, chewing of paraffin, lateral aiad protrusive excursions with the teeth in contact, exertion of Iioht and heavy forces, and tapping of the teeth in centric occlusion. T h e same procedure, except for chewing, was used with and without the occlusal splint. In six of the 11 patients, a jaw jerk reflex was produced during maximal voluntary clenchin/ in centric occlusion by tapping on the chin with a reflex ham1! l e r .
SUMMATION OF TREATMENT SEQUENCE 7"ime 1: Initial examination 7"ime 2: First treatment visit a. EMG without bite plane splint b~ Deliver bite plane splint c. Mark position of lower incisors on splint with mandible in eentric jaw relation d. EMG with bite plane splint in mouth ~Polygraph model 75, Grass Instrument Company, Quincy, Mass. t F M tape recorder 3955, Hewlett Packard, Palo Alto, Calif.
Occlusal splints and T M ] dys/unction
V,,lm,,,. :~:~ N v m b e r :~
323
Time 3: Second treatment visit (at 72 hours) a. Mark position of lower incisors on splint with mandible in eentric jaw relation b. Adjust any interference on splint c. EMG with splint in mouth d. EMG without splint in mouth
Time 4: Third treatment visit (at one month) a. b. e. d.
Mark position of lower incisors with mandible in eentric jaw relation Adjust any interferences EMG with splint in mouth EMG without splint in mouth
EVALUATION OF THE EMG T h e E M G evaluation was done by visual examination of the tracings for asynchronous nmscle activity. A determination was made of the asynchronous activity of the muscles at rest at the beginning, the middle, and the end of the session, and an examination was made of the swallowing pattern, gliding movements, and coordination and synchronization of chewing pattern. T h e recordings of the right masseter muscle during 15 tappings in eentric occlusion with and without the spliltt were replayed with time expansion, the "silent periods" were counted, and their duration was measured. T h e recordings of the other muscles were also replayed, but the silent periods were not measured. The E M G of tlle masseter nmscles during clenching was replayed, and the silent period after the jaw jerk reflex was measured.
STATISTICAL ANALYSIS An analysis of variance was used to test the null hypothesis when comparing: the mean duration of silent periods with and without the occlusal bite plane splint, the mean n u m b e r of silent periods with 'find without the occlusal splint, and the mean duration of silent periods after the jaw jerk reflex at three specific times. A threefactor completely crossed design was used.
RESULTS T h e direction of the m o v e m e n t of the mandible on the splint after 72 hours was most often toward the painful side and anteriorly directed. After 72 hours, six patients moved to the side of the painful joint, one to the opposite side, and one did not move. Of the three patients with pain in both joints, one moved straight forward, and two moved laterally and anteriorly. After one month, the mandibles of five patients stayed in the same position, as after 72 hours. In four patients, the mandibles lnoved a little more in the same direction. The patient who moved to the opposite side after 72 hours had moved to the side of the painful joint after one month. O n e patient moved back to the starting position. T h e extent of the m a n d i b u l a r m o v e m e n t varied from patient to patient and from one session to another, but never exceeded 3.5 + 1.0 ram. After .72 hours, for nine patients, there was a mean anterolateral movement of 1.82 +_ 0.93 ram. T w o patients had a posterolateral mean lnovement of 2.6 + 1.8 ram. After one ntonth, for 10 patients, there was a mean anterolateral movement of 1.78 _+ 0.97 ram. One patient had a posterolateral mean movement of 1.7 ram.
324
Kovaleski and De Boever
J. Prosthet. Dent. March, 1975 II
R. ANT. T E M P O R A L
L.
ANT.
TEMPORAL
R. •P O S T .
TEMPORAL
L. POST.
TEMPORAL
DIGASTRIC
.
.11 9
Fig. 1. With (II) and without (I) splint. Calibration is 50 #v. and 1.second. Table II. Summary of analysis of variance results" Comparison of mean duration of silent period during tapping with splint and without splint Without splint
With splint Mean
MS
Time
(msec.)
2 3 4 2, 3, 4*
23.35 21.67 22.68 22.57
(msgr.) 14.663 1.815 1.815 4.888
,Mean Time •
,
|
2 3 4 2, 3, 4*
(reset.) 21.64 22.27 22.08 21.99
F
d/
p
0.85 0.41 1.33 0.65
1.9 1.9 1.9 1.9
NS NS NS NS
~'Mean of t h r e e sessions.
With respect to symptoms, nine of 11 patients reported pain a n d / o r clicking relieved after 72 hours. All the patients were followed up to two months after the third treatment visit, and the occlusal adjustment was performed according to the technique advocated by Ramfjord and Ashy They all remained symptom free during a six-month follow-up. The silent periods in i5 voluntary taps in centric occlusionare summarized in Table I. The duration of these silent periods was measured, and the results are summarized in Table II. The initial E M G trace usually showed hyperactivity in the right or left posterior temporal muscle. The immediate response of the muscles was a decrease in the E M G activity at rest in six of the subjects. On the other hand, there was an increase in the activity of the suprahyoid muscles in nine patients whenever the splint was in
Occlusal splints and TMJ dysfunction
voh.n~.~3 Number 3
III
325
IV
R. ANT. TEMPORAL
L.
ANT.
R. P O S T .
TEMPORAL
'. . . .
TEMPORAL
go,. - ~ - , - ¢ - - , : : i ' ¢ - - ~ - ~ - , ~
L. POST. T E M P O R A L
DIGASTRIC
illl
Fig. 2. With (III) and without (IV) splint. the mouth. This was immediately reduced when the splint was removed. Typical rest position tracings are shown in Figs. 1 to 3 ~ T i m e s 2, 3, and 4, respectively. DISCUSSION
Although it was previously felt that the mandible was moving posteriorly as the symptoms disappeared, the measurement of the phenomenon does not agree with this concept. The duration of the silent periods with jaw jerk did decrease to within a normal range after one month for all subjects. In none of the patients were the silent periods totally absent, but in three patients, the silent period was not present in one to three of the nine jaw jerks elicited in each session. These patients did not show the most severe clinical symptoms. The number of silent periods in tapping with the splint decreased compared to n u m b e r without the splint (Table I). This decrease was significant (P < 0.05). This suggests a decreased influence of the occlusion on the musculature with the occlusal splint in the mouth. The duration of the silent periods for tapping stayed the same whether or not the splint was in place (Table II). Although the duration of the silent period was slightly longer than reported previously by others (15.3 msec./'~ 10 to 20 msec./~' 8 to 20 msec., ~; and 13 msec.~S), the difference is probably related to the method of measurement and method of tapping. T h e hyperactivity in the posterior part of the temporal muscle has been interpreted as a "splinting action" caused by an attempt to hold the condyle away from the painful areas, ~ and that hyperactivity was mostly on the painful side. In this study, a tendency to hyperactivity on the opposite side was observed. In most of
326
Kovaleski and De Boever
J. l'rosthet. Dent. March, 1975
V
VI
R. ANT. TF2dPC3RA[,
L. ANT.
TEMPORAL
R. POST. T E M P O R A L
L. POST. TEMPORAL
DIGASTRIC
_
..
.
.
.
,
| J
Fig. 3. With (V) and without (VI) splint. the patients, the relaxation of the involved posterior temporal muscles resulted in a movement of the mandible on the occlusal splint toward the involved side. In the patients with both muscles involved, the mandible tended to move straight forward. Only one of the patients moved the mandible distalIy on the occlusal splint after one month. CONCLUSIONS After the use of an occlusal bite plane splint for one month: (1) the mandible moves anteriorly and laterally on an occlt,sal bite' plane splint where there is sufficient centric freedom built into the splint; (2) there is a decrease in TMJ-muscle symptoms provided anterior mandibular movement is not trapped by occlusal interferences, cuspid guidance, a n d / o r incisal guidance on the splint; and (3) there is a decrease in the number of silent periods elicited during tapping with the occlusal splint in the mouth. References I. Granger, E. R.: Occh,sion in Temporonlandibular Joint Pain, J. Am. Dent. Assoc. 56: 659-664, 1958. 2. Hupfauf, L., and Weitkamp, J.: Ergebnisse der Behandlung von funktionsbedingten Erkrankungen des Kausystems mit Aufbissplatten, Dtsch. Zahnaerztl. Z. 24: 347-351, 1969. Kanter, t'.: The Use of Bite Plates, in Schwartz, L., editor: Disorders of the Temporomandibular Joint, Philadelphla, 1959, W. B. Saunders Company, pp. 300-306. 4. Posseh, U.: Physiology of Occlusion and Rehabilitation, Philadelphia, 1962, F. A. Davis Company. 5. Posseh, U.: Treatment of Bruxism by Bite Guards and Bite Plates, J. Can. Dent. Assoc. 29: 77q-779, 1963. ,
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•
Volume 33 Number 3
OccIusal splints and TAll] dysfunction 327
6. Ramfjord, S. P., and Ash, M. M.: Occlusion, ed. 2, Philadelphia, 1971, W. B. Saunders Company. 7. Zarb, G. A., and Thompson, G. W.: Assessment of Clinical Treatment of Patients With Temporomandibular Joint Dysfunction, J. PROSTnET. DENT. 24: 542-554, 1970. 8. Perry, H. T.: Muscular Changes Associated With Temporomandibular Joint Dysfunction, J. Am. Dent. Assoc. 54: 644-653, 1957. 9. Ramfjord, S. P.: Dysfunctional, Temporomandibular Joint and Muscle Pain, J. PROST~IET. DENT. 11: 353-374, 1961. 10. Ahlgren, J.: An Intercutaneous Needle Electrode for Kinesiologic EMG Studies, Acta Odontol. Scand. 25:15-I9, 1967. 11. Jarabak, J. R.: Electromyographic Analysis of Muscular and Temporomandibular Joint Disturbances Due to Imbalances of Occlusion, Angle Orthod. 24: 170.190, 1956. 12. Lous, I., Sheik-OI-Eslam, A., and Moller, E.: Postural Activity in Subjects With Functional,Disorders of the Chewing Apparatus, Scand. J. Dent. Res. 78: 404-410, 1970. 13. Yemm, R.: Temporomandibular Dysfunction and Masseter Muscle Response to Experimental Stress, Br. Dent. J. 127: 508-510, 1969. 14. Schulte, W.: Zur funktionellern Behandlung der Myo-arthropathien des Kauorganes: Ein diagnostisches und physio-therapeutisches Programm, Dtsch. Zahnaerztl. Z. 25: 422-436, 1970. 15. Ahlgren,'J.: The Silent Period in the EMG of the Jaw Muscles During Mastication and Its Relationship to Tooth Contact, Acta Odontol. Scand. 27: 219-227, 1969. 16. Hannam, A. G., Matthews, B., and Yemm, P.: Changes in the Activity of the Masseter Muscle Following Tooth Contact in Man, Arch. Oral Biol. 14: 1401-1406, 1969. 17. Matthews, B., and Yemm, R. : A Silent Period in the Masseter Eleetromyogram Following Tooth Contact in Subjects Wearing Full Dentures, Arch. Oral Biol. 15: 531-535, 1970. 18. Griffin, C. J., and Munro, R. R. : Electromyography of Jaw Closing Muscles in the OpenClose-Clench in Man, Arch. Oral Biol. 14: 141-149, 1969. 19. Besette, R., Bishop, B., and Mohl, N.: Duration of Masseteric Period in Patients With TMJ-Syndrome, Int. Assoc. Dent. Res. Abst. No. 406, March, 1971. 20. Griffin, C. J., and Munro, R. R.: Electromyography of the Masseter and Anterior Temporalis Muscles in Patient With Temporomandibular Dysfunction, Arch. Oral Biol. 16: 929-949, 1971. DR. KOVALESKI ]DEPARTMENT OF OCCLUSION SCHOOL OF DENTISTRY THE UNIVERSITY OF MICHIGAN
AN,~ ARBOR, MICH. 42104 DR. DE BOEVER UNIVERSITY OF GHENT DIENST PROTHETODONTIE AKADEMISCH ZIEKENHUIS bE PINTELAAN, 135 B-9000 CHANT, BELGIUM