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Influence of occlusal patterns on movements of the mandible
CLASSIC ARTICLE Influence of occlusal patterns on movements of the mandible N. Brill, LDS,* S. Schu¨beler, LDS,** and G. Tryde, LDS*** Royal Dental College, Copenhagen, Denmark
I
t is common knowledge that signals arising in cutaneous receptors modify muscle activity. Moreover, it has been demonstrated1 that impulses from receptors located in the oral mucosa influence the performance of the musculature of the cheek, lip, and tongue of complete denture patients. Lammie, Perry, and Crumm2 have reported that the electromyographic pattern of chewing muscles can be changed when the occlusal patterns of complete dentures are changed. Perry3 and Campbell4 have observed that a faulty occlusion is often associated with pain in muscles of the head and neck. This evidence suggests (1) that an eccentric occlusion in complete dentures may force a change upon the movement pattern of the musculature and (2) that pathologic changes may arise in muscles as they strive to cope with an eccentric occlusion. This experimental study attempts to check the validity of these suggestions.
SELECTION OF SUBJECTS A group of 15 edentulous subjects ranging in age from 37 to 75 was selected for the study. Seven subjects were men and 8 were women. Oral and general health conditions of all subjects were good. The ridge form was such that good denture retention and stability could be expected. The subjects were well balanced and cooperative mentally. Patients with a nervous disposition were not accepted because their mental state might influence muscle activity and complicate the interpretation of experimental findings.
EXPERIMENTAL DENTURES One upper and two identical complete lower dentures were made for each subject. One of the lower dentures was processed on the master cast, whereas the second denture was processed on a duplicate cast. A preliminary recording was made of the retruded position of the mandible in relation to the maxillae, and the
*Associate Professor, Department of Prosthetic Dentistry. **Instructor, Department of Prosthetic Dentistry. ***Research Fellow, Department of Prosthetic Dentistry. Reprinted with permission from J Prosthet Dent 1962;12:255-61. J Prosthet Dent 2005;93:207-11.
MARCH 2005
casts were mounted on a Dentatus articulator. A protrusive record was made so that the teeth could be arranged in balanced occlusion. The incisal table was set horizontally. The dentures were remounted on the articulator after processing, and occlusal errors were eliminated by grinding. At this stage, a second recording was obtained of the ‘‘muscular position’’ of the mandible in relation to the maxillae.2,5 Marks were obtained on the occlusal surfaces of the teeth by light tapping movements performed by the patients against articulating paper placed between the teeth. The marks, principally on the protrusive facets, were reduced until the dentures were no longer displaced on their foundations and until the patient assessed a comfortable feeling when the teeth were occluded. Often, the patients stated spontaneously, ‘‘Now the dentures fit,’’ or ‘‘Now the teeth meet properly.’’ This second recording accommodated the occlusion in the muscular position. Each lower denture was worn alternately against the upper denture and adjusted until the patient was unable to indicate a preference for either lower denture. This was achieved generally in 10 to 12 days. When the lower dentures could be worn interchangeably against the upper denture, one of the lower dentures and the upper denture were remounted on the articulator. The original height between the upper and lower members of the articulator and the horizontal inclination of the incisal table were retained. The condylar balls were pushed back 3 mm. (Fig. 1), and they were stabilized in this position irrespectively of the individually recorded inclination of the condylar path. The lower denture was removed from the articulator mounting and was cut into three parts, i.e., the two blocks carrying the molars and premolars were separated from the basal part of the denture. The anterior teeth remained attached to the intact denture base (Fig. 2). If necessary, the anterior teeth were ground to eliminate incisal interferences created by the new position. The two blocks which contained the lower posterior teeth were reintercuspated with the posterior teeth of the upper denture and attached in position with sticky wax. Then, the lower posterior teeth were reattached to the basal part of the lower denture (Fig. 3) with cold-curing acrylic resin. Consequently, the patients had to protrude the lower jaw to obtain maximal intercuspation of the teeth with this denture. THE JOURNAL OF PROSTHETIC DENTISTRY 207
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 2. A block of acrylic resin containing premolars and molars is separated from the lower denture. The articulator has been set in protrusion with the condylar balls displaced posteriorly 3 mm.
Fig. 1. A, The condylar ball is in the most forward position. B, The condylar ball has been displaced posteriorly 3 mm. C and D, The corresponding positions of the incisal guide pin.
Fig. 3. A, The denture constructed in the muscular position is in maximal occlusion. B, The denture constructed in the protrusive position is in maximal occlusion.
The lower denture which intercuspates in protrusion will be called denture P, and that which accommodates the muscular position will be called denture M.
EXPERIMENTAL PROCEDURES Various tests for each subject were performed with the upper denture alternately opposed by dentures M and P. The subjects sat in a dental chair in an upright position with the back and head supported by the chair. 208
The subjects were instructed to perform a series of light, and then a series of firm, tapping movements with denture M. They were told always to start and stop these movements with the teeth in occlusion and to perform each series of movements twenty-five times. The examiner gently retracted the lips of the subjects to determine if the teeth contacted in maximal occlusion or in a protrusive or retrusive occlusal position. Denture M was removed and denture P inserted. The subject was now instructed to close firmly with denture P. He was told that he might experience a sensation of inaccuracy and get the impression that he could not ‘‘bring home’’ the teeth, but that he should search with the teeth for a position in which they met properly and accustom himself to this position. Usually, this was achieved in 20 to 30 seconds. Then, the subject tapped lightly and subsequently firmly twenty-five times, and the observations on the position of the teeth at contact were made. The upper denture and denture P were given to the subject. He was told to use them for 1 week and then return for a new series of tests. Upon returning, the patient went through the light and firm tapping with denture P, and then the procedure was repeated with denture M. The possibility of pain in various structures during the course of the testing was studied by digital examination in the location of (1) the upper and lower insertions of both masseter muscles, (2) the insertions of both temporal muscles on the coronoid processes, (3) both external pterygoid muscles, using a method suggested by Vaughan,6 (4) the upper and lower denture foundations, and (5) both temporomandibular joints. All structures were examined at both testing sessions and also on a third occasion, usually 1 week later. Pain or tenderness was not observed at the beginning of the experiment either spontaneously by the patient or by palpation.
RESULTS The results from the tapping tests are recorded in Table I. From the second and sixth columns, it is evident VOLUME 93 NUMBER 3
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
Table I. Number of maximal occlusions obtained in 15 subjects* First occasion
Second occasion, 7 days later
Subject
Light and firm tapping on denture M
Light tapping on denture P
Firm tapping on denture P
Light tapping on denture P
Firm tapping on denture P
Light and firm tapping on denture M
M.J. A.G. H.J. H.L. E.S. M.M. E.J. A.F. E.N. S.N. A.P. H.N. E.R. O.L. K.E. Totals
25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 375
0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 2
12 10 21 15 13 20 22 24 10 22 15 16 0 5 1 205
0 0 0 0 0 0 0 0 0 0 4 0 4 0 0 8
24 25 23 25 25 25 25 22 25 25 19 21 19 25 25 353
25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 375
*Tests were performed 7 days apart. On each occasion, both light and firm tapping were performed twenty-five times. Each subject tapped two different lower dentures consecutively against the same upper denture.
Table II. Location of symptoms produced by dentures constructed with maximal occlusion occurring with the mandible in a protrusive position Location Denture foundation
Subject
Masseter muscle
A.G. E.N. S.N.
Right Right and left
Right
E.J. A.P. H.L. M.M. E.R. O.L.
Right and left
Right
External pterygoid muscle
Coronoid process
Right and left Right and left Right and left
Right and left
Location of symptoms persisting more than 1 week
Reduced soreness of both coronoid processes; no symptoms 7 weeks later
Right and left Right Right
Right and left Right and left Right and left
K.E. Totals Right Left
11 6 5
Left
5 3 2
Right and left
Right and left Right and left
Right and left 6 3 3
Right and left 14 8 6
that an ‘‘eccentric’’ occlusal pattern can change the movement pattern of the mandible. All subjects on both occasions closed straight into maximal occlusion with denture M regardless of whether the closing movements were performed with force or with a minimum of muscle activity (second and seventh columns). At both testing sessions with denture P, the mandible closed in a protrusive position when some muscular force was used in tapping the teeth (fourth and sixth 1 colMARCH 2005
Reduced soreness of left coronoid process; no symptoms 1 week later
umns). However, when minimal force was applied with denture P, the teeth met in maximal occlusion only ten of a possible 750 times for all subjects on both occasions (third and fifth columns). The teeth contacted posteriorly to maximal occlusion the remaining 740 times. The results of the digital examination for pain are seen in Table II. The incidence of symptoms was recorded for each side. Findings for only 10 subjects were entered because no symptoms could be detected for the other 5, except for 1 subject who stated that 209
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
sometimes he had an awkward feeling when the teeth contacted. No entries were made regarding the temporomandibular joints because of the absence of all subjective and objective symptoms. Similarly, symptoms in the upper denture foundations were never encountered. Painful symptoms appeared only in the right lower denture foundation for 1 subject. Painful reactions were elicited both on the lower ridges and in the musculature of 5 subjects. Nine persons reacted with pain when the external pterygoid muscles or insertions of the other muscles were palpated. However, none of these subjects were aware that something was wrong with the musculature. Only 6 subjects complained of their dentures, and those subjects had pain in the denture foundation. When denture M was substituted for denture P, the symptoms disappeared in most instances within 1 week.
DISCUSSION These findings support the theory suggested previously5 that opening and closing movements of the mandible are executed by a well-defined and stable innervation pattern. At both testing sessions, all patients invariably obtained maximal occlusion with denture M regardless of whether the movements were performed with light or heavy force. Maximal occlusion was obtained in spite of the fact that at the second testing session, the subjects had been exposed to new and ‘‘foreign’’ mechanoreceptive signals deflecting the mandible during the preceding week (Table I, seventh column). This concept of a fundamental innervation pattern is also supported by the observation that with light tapping on dentures P, all subjects closed the teeth in a retruded position from maximal occlusion. The mandible was closer to the muscular position in this retruded position. However, the opening and closing innervation pattern can be changed by interceptive occlusal contacts. The incongruency between the movement pattern and occlusal pattern was modified when each patient wore denture P. The modification in 4 subjects was so successful that the performance of the new innervation pattern was described and accepted as being just as expedient and comfortable as the performance of the unmodified pattern. The change in the movement pattern of the mandible is explained in the following manner. When light tapping was performed with denture P, the influence of mechanoreceptive signals from the denture foundations was negligible (Table I, third and fifth columns). However, when tapping was performed energetically, the firing of the gingival mechanoreceptors increased, and consequently, the mandibular movements changed (compare the third and fifth columns with the fourth and sixth col210
umns of Table I). The ensuing movements tended to accommodate the eccentric occlusal pattern, particularly when denture P had been worn for 1 week (compare the fourth column with the sixth column of Table I). Denture P inflicted injuries upon one or more structures in 10 subjects. Only injuries to the denture foundation were recognized subjectively. Injuries to muscles were unnoticed. This observation should be kept in mind by dentists when they examine the occlusion of dentures. What seems by visual examination to be a perfect occlusion may be one to which the patient has adjusted the mandibular musculature, thus obscuring a potentially dangerous disharmony between the occlusal pattern and the fundamental innervation pattern. No attempt should be made to construe these findings as a devaluation of jaw recording procedures in complete denture construction. Only a limited number of subjects could tolerate the established discordance between the fundamental innervation pattern and the occlusal pattern. Although all patients were able to change the movement pattern to accommodate the eccentric occlusion of the protrusive dentures, this change was achieved, in most subjects, at the expense of the health of various structures.
SUMMARY One complete upper and two complete lower dentures were constructed for each of 15 edentulous subjects. One lower denture accommodated maximal occlusion with the mandible in the muscular position, and the second lower denture accommodated maximal occlusion with the mandible in a protruded position. It was shown that the movement pattern of the mandible can change to accommodate the protruded occlusal position. The dentures constructed to the protruded position caused painful conditions for 10 subjects. The locations of these conditions were (1) the lower denture foundations, (2) the insertions of the masseter muscles, (3) the insertions of the temporal muscles on the coronoid processes, and (4) the external pterygoid muscles. No pain was elicited in the temporomandibular joints. The subjects complained of pain only when it was in the denture foundation. Injury in the other structures was unnoticed. Therefore, the dentist is obliged to examine these muscular structures to determine if the occlusal pattern of dentures is in accord with the movement pattern of the mandible. REFERENCES 1. Brill N, Tryde G, Schu¨beler S. The role of exteroceptors in denture retention. Prosthet Dent 1959;9:761-8. 2. Lammie GA, Perry HT Jr, Crumm BD. Certain observations on a complete denture patient I and II. Prosthet Dent 1958;8:786-95. 929-39. 3. Perry HT Jr. Muscular changes associated with temporomandibular joint dysfunction. J Am Dent Assoc 1957;54:644-53.
VOLUME 93 NUMBER 3
¨ BELER, AND TRYDE BRILL, SCHU
4. Campbell J. Distribution and treatment of pain in temporomandibular arthroses. Br Dent J 1958;105:393-407. 5. Brill N, Lammie GA, Osborne J, Perry HT. Mandibular positions and mandibular movements. Br Dent J 1959;106:391-400. 6. Vaughan HC. Temporomandibular joint pain. A new diagnostic approach. J Prosthet Dent 1954;4:694-708.
MARCH 2005
THE JOURNAL OF PROSTHETIC DENTISTRY
0022-3913/$30.00 Copyright Ó 2005 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2004.11.004
211
I
t is common knowledge that signals arising in cutaneous receptors modify muscle activity. Moreover, it has been demonstrated1 that impulses from receptors located in the oral mucosa influence the performance of the musculature of the cheek, lip, and tongue of complete denture patients. Lammie, Perry, and Crumm2 have reported that the electromyographic pattern of chewing muscles can be changed when the occlusal patterns of complete dentures are changed. Perry3 and Campbell4 have observed that a faulty occlusion is often associated with pain in muscles of the head and neck. This evidence suggests (1) that an eccentric occlusion in complete dentures may force a change upon the movement pattern of the musculature and (2) that pathologic changes may arise in muscles as they strive to cope with an eccentric occlusion. This experimental study attempts to check the validity of these suggestions.
SELECTION OF SUBJECTS A group of 15 edentulous subjects ranging in age from 37 to 75 was selected for the study. Seven subjects were men and 8 were women. Oral and general health conditions of all subjects were good. The ridge form was such that good denture retention and stability could be expected. The subjects were well balanced and cooperative mentally. Patients with a nervous disposition were not accepted because their mental state might influence muscle activity and complicate the interpretation of experimental findings.
EXPERIMENTAL DENTURES One upper and two identical complete lower dentures were made for each subject. One of the lower dentures was processed on the master cast, whereas the second denture was processed on a duplicate cast. A preliminary recording was made of the retruded position of the mandible in relation to the maxillae, and the
*Associate Professor, Department of Prosthetic Dentistry. **Instructor, Department of Prosthetic Dentistry. ***Research Fellow, Department of Prosthetic Dentistry. Reprinted with permission from J Prosthet Dent 1962;12:255-61. J Prosthet Dent 2005;93:207-11.
MARCH 2005
casts were mounted on a Dentatus articulator. A protrusive record was made so that the teeth could be arranged in balanced occlusion. The incisal table was set horizontally. The dentures were remounted on the articulator after processing, and occlusal errors were eliminated by grinding. At this stage, a second recording was obtained of the ‘‘muscular position’’ of the mandible in relation to the maxillae.2,5 Marks were obtained on the occlusal surfaces of the teeth by light tapping movements performed by the patients against articulating paper placed between the teeth. The marks, principally on the protrusive facets, were reduced until the dentures were no longer displaced on their foundations and until the patient assessed a comfortable feeling when the teeth were occluded. Often, the patients stated spontaneously, ‘‘Now the dentures fit,’’ or ‘‘Now the teeth meet properly.’’ This second recording accommodated the occlusion in the muscular position. Each lower denture was worn alternately against the upper denture and adjusted until the patient was unable to indicate a preference for either lower denture. This was achieved generally in 10 to 12 days. When the lower dentures could be worn interchangeably against the upper denture, one of the lower dentures and the upper denture were remounted on the articulator. The original height between the upper and lower members of the articulator and the horizontal inclination of the incisal table were retained. The condylar balls were pushed back 3 mm. (Fig. 1), and they were stabilized in this position irrespectively of the individually recorded inclination of the condylar path. The lower denture was removed from the articulator mounting and was cut into three parts, i.e., the two blocks carrying the molars and premolars were separated from the basal part of the denture. The anterior teeth remained attached to the intact denture base (Fig. 2). If necessary, the anterior teeth were ground to eliminate incisal interferences created by the new position. The two blocks which contained the lower posterior teeth were reintercuspated with the posterior teeth of the upper denture and attached in position with sticky wax. Then, the lower posterior teeth were reattached to the basal part of the lower denture (Fig. 3) with cold-curing acrylic resin. Consequently, the patients had to protrude the lower jaw to obtain maximal intercuspation of the teeth with this denture. THE JOURNAL OF PROSTHETIC DENTISTRY 207
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 2. A block of acrylic resin containing premolars and molars is separated from the lower denture. The articulator has been set in protrusion with the condylar balls displaced posteriorly 3 mm.
Fig. 1. A, The condylar ball is in the most forward position. B, The condylar ball has been displaced posteriorly 3 mm. C and D, The corresponding positions of the incisal guide pin.
Fig. 3. A, The denture constructed in the muscular position is in maximal occlusion. B, The denture constructed in the protrusive position is in maximal occlusion.
The lower denture which intercuspates in protrusion will be called denture P, and that which accommodates the muscular position will be called denture M.
EXPERIMENTAL PROCEDURES Various tests for each subject were performed with the upper denture alternately opposed by dentures M and P. The subjects sat in a dental chair in an upright position with the back and head supported by the chair. 208
The subjects were instructed to perform a series of light, and then a series of firm, tapping movements with denture M. They were told always to start and stop these movements with the teeth in occlusion and to perform each series of movements twenty-five times. The examiner gently retracted the lips of the subjects to determine if the teeth contacted in maximal occlusion or in a protrusive or retrusive occlusal position. Denture M was removed and denture P inserted. The subject was now instructed to close firmly with denture P. He was told that he might experience a sensation of inaccuracy and get the impression that he could not ‘‘bring home’’ the teeth, but that he should search with the teeth for a position in which they met properly and accustom himself to this position. Usually, this was achieved in 20 to 30 seconds. Then, the subject tapped lightly and subsequently firmly twenty-five times, and the observations on the position of the teeth at contact were made. The upper denture and denture P were given to the subject. He was told to use them for 1 week and then return for a new series of tests. Upon returning, the patient went through the light and firm tapping with denture P, and then the procedure was repeated with denture M. The possibility of pain in various structures during the course of the testing was studied by digital examination in the location of (1) the upper and lower insertions of both masseter muscles, (2) the insertions of both temporal muscles on the coronoid processes, (3) both external pterygoid muscles, using a method suggested by Vaughan,6 (4) the upper and lower denture foundations, and (5) both temporomandibular joints. All structures were examined at both testing sessions and also on a third occasion, usually 1 week later. Pain or tenderness was not observed at the beginning of the experiment either spontaneously by the patient or by palpation.
RESULTS The results from the tapping tests are recorded in Table I. From the second and sixth columns, it is evident VOLUME 93 NUMBER 3
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
Table I. Number of maximal occlusions obtained in 15 subjects* First occasion
Second occasion, 7 days later
Subject
Light and firm tapping on denture M
Light tapping on denture P
Firm tapping on denture P
Light tapping on denture P
Firm tapping on denture P
Light and firm tapping on denture M
M.J. A.G. H.J. H.L. E.S. M.M. E.J. A.F. E.N. S.N. A.P. H.N. E.R. O.L. K.E. Totals
25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 375
0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 2
12 10 21 15 13 20 22 24 10 22 15 16 0 5 1 205
0 0 0 0 0 0 0 0 0 0 4 0 4 0 0 8
24 25 23 25 25 25 25 22 25 25 19 21 19 25 25 353
25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 375
*Tests were performed 7 days apart. On each occasion, both light and firm tapping were performed twenty-five times. Each subject tapped two different lower dentures consecutively against the same upper denture.
Table II. Location of symptoms produced by dentures constructed with maximal occlusion occurring with the mandible in a protrusive position Location Denture foundation
Subject
Masseter muscle
A.G. E.N. S.N.
Right Right and left
Right
E.J. A.P. H.L. M.M. E.R. O.L.
Right and left
Right
External pterygoid muscle
Coronoid process
Right and left Right and left Right and left
Right and left
Location of symptoms persisting more than 1 week
Reduced soreness of both coronoid processes; no symptoms 7 weeks later
Right and left Right Right
Right and left Right and left Right and left
K.E. Totals Right Left
11 6 5
Left
5 3 2
Right and left
Right and left Right and left
Right and left 6 3 3
Right and left 14 8 6
that an ‘‘eccentric’’ occlusal pattern can change the movement pattern of the mandible. All subjects on both occasions closed straight into maximal occlusion with denture M regardless of whether the closing movements were performed with force or with a minimum of muscle activity (second and seventh columns). At both testing sessions with denture P, the mandible closed in a protrusive position when some muscular force was used in tapping the teeth (fourth and sixth 1 colMARCH 2005
Reduced soreness of left coronoid process; no symptoms 1 week later
umns). However, when minimal force was applied with denture P, the teeth met in maximal occlusion only ten of a possible 750 times for all subjects on both occasions (third and fifth columns). The teeth contacted posteriorly to maximal occlusion the remaining 740 times. The results of the digital examination for pain are seen in Table II. The incidence of symptoms was recorded for each side. Findings for only 10 subjects were entered because no symptoms could be detected for the other 5, except for 1 subject who stated that 209
¨ BELER, AND TRYDE BRILL, SCHU
THE JOURNAL OF PROSTHETIC DENTISTRY
sometimes he had an awkward feeling when the teeth contacted. No entries were made regarding the temporomandibular joints because of the absence of all subjective and objective symptoms. Similarly, symptoms in the upper denture foundations were never encountered. Painful symptoms appeared only in the right lower denture foundation for 1 subject. Painful reactions were elicited both on the lower ridges and in the musculature of 5 subjects. Nine persons reacted with pain when the external pterygoid muscles or insertions of the other muscles were palpated. However, none of these subjects were aware that something was wrong with the musculature. Only 6 subjects complained of their dentures, and those subjects had pain in the denture foundation. When denture M was substituted for denture P, the symptoms disappeared in most instances within 1 week.
DISCUSSION These findings support the theory suggested previously5 that opening and closing movements of the mandible are executed by a well-defined and stable innervation pattern. At both testing sessions, all patients invariably obtained maximal occlusion with denture M regardless of whether the movements were performed with light or heavy force. Maximal occlusion was obtained in spite of the fact that at the second testing session, the subjects had been exposed to new and ‘‘foreign’’ mechanoreceptive signals deflecting the mandible during the preceding week (Table I, seventh column). This concept of a fundamental innervation pattern is also supported by the observation that with light tapping on dentures P, all subjects closed the teeth in a retruded position from maximal occlusion. The mandible was closer to the muscular position in this retruded position. However, the opening and closing innervation pattern can be changed by interceptive occlusal contacts. The incongruency between the movement pattern and occlusal pattern was modified when each patient wore denture P. The modification in 4 subjects was so successful that the performance of the new innervation pattern was described and accepted as being just as expedient and comfortable as the performance of the unmodified pattern. The change in the movement pattern of the mandible is explained in the following manner. When light tapping was performed with denture P, the influence of mechanoreceptive signals from the denture foundations was negligible (Table I, third and fifth columns). However, when tapping was performed energetically, the firing of the gingival mechanoreceptors increased, and consequently, the mandibular movements changed (compare the third and fifth columns with the fourth and sixth col210
umns of Table I). The ensuing movements tended to accommodate the eccentric occlusal pattern, particularly when denture P had been worn for 1 week (compare the fourth column with the sixth column of Table I). Denture P inflicted injuries upon one or more structures in 10 subjects. Only injuries to the denture foundation were recognized subjectively. Injuries to muscles were unnoticed. This observation should be kept in mind by dentists when they examine the occlusion of dentures. What seems by visual examination to be a perfect occlusion may be one to which the patient has adjusted the mandibular musculature, thus obscuring a potentially dangerous disharmony between the occlusal pattern and the fundamental innervation pattern. No attempt should be made to construe these findings as a devaluation of jaw recording procedures in complete denture construction. Only a limited number of subjects could tolerate the established discordance between the fundamental innervation pattern and the occlusal pattern. Although all patients were able to change the movement pattern to accommodate the eccentric occlusion of the protrusive dentures, this change was achieved, in most subjects, at the expense of the health of various structures.
SUMMARY One complete upper and two complete lower dentures were constructed for each of 15 edentulous subjects. One lower denture accommodated maximal occlusion with the mandible in the muscular position, and the second lower denture accommodated maximal occlusion with the mandible in a protruded position. It was shown that the movement pattern of the mandible can change to accommodate the protruded occlusal position. The dentures constructed to the protruded position caused painful conditions for 10 subjects. The locations of these conditions were (1) the lower denture foundations, (2) the insertions of the masseter muscles, (3) the insertions of the temporal muscles on the coronoid processes, and (4) the external pterygoid muscles. No pain was elicited in the temporomandibular joints. The subjects complained of pain only when it was in the denture foundation. Injury in the other structures was unnoticed. Therefore, the dentist is obliged to examine these muscular structures to determine if the occlusal pattern of dentures is in accord with the movement pattern of the mandible. REFERENCES 1. Brill N, Tryde G, Schu¨beler S. The role of exteroceptors in denture retention. Prosthet Dent 1959;9:761-8. 2. Lammie GA, Perry HT Jr, Crumm BD. Certain observations on a complete denture patient I and II. Prosthet Dent 1958;8:786-95. 929-39. 3. Perry HT Jr. Muscular changes associated with temporomandibular joint dysfunction. J Am Dent Assoc 1957;54:644-53.
VOLUME 93 NUMBER 3
¨ BELER, AND TRYDE BRILL, SCHU
4. Campbell J. Distribution and treatment of pain in temporomandibular arthroses. Br Dent J 1958;105:393-407. 5. Brill N, Lammie GA, Osborne J, Perry HT. Mandibular positions and mandibular movements. Br Dent J 1959;106:391-400. 6. Vaughan HC. Temporomandibular joint pain. A new diagnostic approach. J Prosthet Dent 1954;4:694-708.
MARCH 2005
THE JOURNAL OF PROSTHETIC DENTISTRY
0022-3913/$30.00 Copyright Ó 2005 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2004.11.004
211