- Email: [email protected]
Daily variations in occlusal contacts
TEMPOROMANDIBULAR SECTION
JOINT
l
OCCLUSION
EDITOR
GEORGE A. ZARB
Daily variations
in occlusal contacts
D. C. Berry, M.D.S., Ph.D.,* and B. P. Singh, M.D.S.** University of Bristol, Dental School, Bristol, England
Wl cc usa1contact of the teeth occurs during functional as well as parafunctional movements of the mandible that are sometimes related to facial or oral expressions of emotion.‘s2 These functional and parafunctional tooth contacts are influenced by the collective activity of the mandibular muscles and.are coordinated by .the peripheral and central nervous systems. Any alteration in normal muscular or neural physiology will likely have some effect on occlusal contacts. In addition to nervous system control, normal rhythmic contraction and relaxation of muscles depend on the availability of nutrients from arterial blood and removal of metabolites by venous blood.3 Availability of nutrients and fast removal of metabolites is important in muscle physiology because only a maximum of 25% of energy generated can be used for muscle contraction, while the remaining 75% is lost as heat.’ Excluding deficient cardiac output, reduced arterial flow and venous return may be due to increased intramuscular pressure during contraction.3*5 On exercise, intramuscular pressure can exceed the blood pressure and completely stop _ . arterial flo~.~ As a result oxygen debt occurs in muscles during heavy and prolonged contractile activity.7-9 Kumazava and Mizumura” have observed that the cessation of blood supply to the muscles results in complete loss of sensory impulses from muscle spindles, tendon organs, and peripheral receptors responsible for monosynaptic and polysynaptic activities in skeletal muscles. In muscles of the calf, this loss of sensory innervation results in claudication; in the lateral pterygoid muscle it may result in deviation of the mandible on opening and closing.6 The rate of venous return and clearance of metabolites is reduced during function and increased during rest. Arterial flow and the availability of nutrients are affected similarly by function and rest.8 Muscle activity, therefore, is maximum and best coordinated in the morning and reduced and less coordinated in the *Professor, University of Bristol, Dental School. **Reader in Dentistry, Banaras Hindu University, Varanasi, India; presently, Honorary Visiting Lecturer, University of Bristol, Dental School.
386
Fig. 1. Occlusal and incisal contacts are marked with articulating ribbon.
evening after the mental and physical activities of the day. For example, the walking pattern in the morning is balanced and easy while irregular and less well balanced in the evening. This variation could also be evident for muscles that control mandibular movements and, therefore, occlusal contacts. Unless one is a bruxer, there is reduced activity of the mandibular muscles at night. During the day muscle activity is increased by deglutition, conversation, expression, mastication, and bruxomania.” Therefore, it is evident that rhythmic and coordinated contraction and relaxation of mandibular muscles vary during the day, with maximum efficiency in the morning and minimum efficiency in the evening. It is reasonable to expect that occlusal contacts may also vary during the day, being at a maximum in the morning and a minimum in the evening. Perhaps the displaceability of the periodontal membrane allows enough mobility of teeth to permit maximum function throughout the day. This article will describe a study of daily variations in occlusal contacts based on this hypothesis. MATERIAL
AND METHODS
Patients for the present study were selected from dental nurse trainees at Bristol Dental School (Table
SEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY VARIATIONS
IN OCCLUSAL CONTACTS
Table I. Patient statistics
Patient No.
Age
(yrs)
Occlusion (Angle classification)
1
18
Class I
2 3 4 5 6 7 8 9
17 18
Class I Class II/ 1
18
Class I Class I Class III Class I Class III Class I Class III Class I: 6 Class II, div 1: 1 Class III: 3
10 Average
16 17 19 19 21
19 18.2
No. of teeth present 26 28 26 28 24 22 26 25 32 28 26.5
Lip competence
Orthodontic treatment
Occlusal wear
I
No
No
HC I I HC HC
No Yes No Yes Yes
No Yes No No No No
NC
Yes
HC
Yes
No
NC NC NC: 3
No Yes Yes: 6 No: 4
Yes No Yes: 2 No: 8
HC: 4 I: 3
Maximum oral opening
(mm) 45 28 50 43 42 41 45 45 40 50 42.8
TMJ Deviation of mandible No No Yes No No No No No Yes No Yes: 2 No: 8
dysfunction No Yes No No No No No No No No Yes: 1 No: 9
I = Incompetent; HC = habitually competent;and NC = naturally competent.
I). The age of the 10 women ranged from 17 to 21 years with a mean of 18.2 years. There were 22 to 32 teeth present in each patient with a mean of 26.5 teeth. The extent of dental restorations was not noted. According to Angle’s classification of maxillomandibular relationships, six were Class I; one was Class II, division 1; and three were Class III. There were naturally competent lips in three patients, habitually competent lips in four patients, and incompetent lips in three patients. Six had orthodontic treatment with or without extraction. There was no occlusal or incisal wear in eight patients, and significant occlusal and incisal wear in one patient. The average oral opening was 42.8 mm. Maximum opening varied, with a range of 40 to 50 mm at the incisors in all but one patient, in whom the opening was 28 mm. This patient developed temporomandibular joint dysfunction syndrome 3 months before the study. There was no pain or other dysfunctional symptoms in the other nine patients. Occlusal contacts were recorded with articulating paper 0.0475 tcm0.0525 mm thick while the patients were seated in a dental chair. Patients were asked to close the teeth firmly to the intercuspal position from habitual maximum opening of the jaws. The occlusal contacts were marked on each side separately (Fig. 1). The mandibuliar arch was divided into left posterior, anterior, and right posterior segments. The two most heavily colored marks in each of the three segments were recorded (Fig. 2). These marks were graded 1 to 6, depending on intensity, with 1 being the heaviest mark. The total number of marked teeth in the maxillae and the mandible was counted and recorded.
THE JOURNAL OF PROSTHETIC DENTISTRY
The occlusal contacts were classified as diffuse or accentuated according to the distribution on each tooth. One or two heavy marks on a tooth was considered accentuated, while a greater number of light marks was considered diffuse. Occlusal contacts were recorded at 9:00 AM and 4:00 PM for 3 days in a 2-week period. After 30 minutes of rest with the EMG 120 (Biofeedback Systems Ltd., Manchester, England) used for biofeedback therapy, occlusal contacts were again recorded at 4:40 PM.” Different colors of articulating paper were used to differentiate each daily recording. RESULTS Articulating paper marks on maxillary and mandibular teeth were observed morning and evening. Specific notation was made of (1) the total number of teeth in contact in both arches in the intercuspal position, (2) accentuated or diffuse contacts, and (3) the six heaviest contacts on the mandibular teeth: two each in the anterior, right posterior, and left posterior segments. Total number of teeth in contact. At most observations there were more teeth in contact in the morning than in the evening (Fig. 3, Table II). On one day an increased number of contacts was noted in the evening in three patients. The number of occlusal contacts in the morning and the evening increased in some patients on the second- and third-day observation as compared with the first day. Compared to the mean of 26.5 teeth present (Table I), the mean number of teeth in contact in the morning was found to be 20.7 on the first day, 20.9 on the second day, and 21.2 on the third day. The mean number of teeth in contact in the evening was 18.4 on
387
BERRY AND
MORNING
EVENING DAY-9
IT.
U’ULX
TC =)I+
A/O’
Tc=/C
TjD
DAY-2
IT.
u-u;
TCs/4
A/C-
u
u;
x=24 TC.NQOF
A/DTESTN IN CONTACT
TC.16 A= ACCENTUATED
Dz DIFFUSE
Fig. 2. Tooth contacts for patient No. 1 are shown for both morning and evening on 3 separate days.
the first day, 18.8 on the second day, and 17.6 on the third day. The mean number of teeth in contact for all the days was 20.92 in the morning and 18.25 in the evening, a difference of 2.67 teeth. On statistical analysis t was 2.88, which was significant at the .02 level. Accentuated or diffuse contacts. A large number of heavy or light occlusal contacts on all or most of the teeth was considered diffuse, while one or two heavy or light marks on a few teeth was considered accentuated (Fig. 4, Table III). I n most of the patients, occlusal contacts were found to be diffuse in the morning and accentuated in the evening. The number of patients with diffuse contacts in the morning increased from the first day to the second day and from the second day to the third day. Evening contacts in one patient were diffuse for all three recordings, while three patients had diffuse contacts on only one of the three evenings. In the morning 66.6% of all contacts were diffuse and 33.3% were accentuated. In the evening 80% of all contacts were accentuated and 20% were diffuse. These findings were statistically significant at the .02 level. 388
Six heaviest contacts. The six heaviest occlusal or incisal contacts, two each in the anterior, left posterior, and right posterior segments, were found to be different in the morning and the evening, and on all three recordings (Fig. 5, Table II). The sixth contact could not always be seen, as only one mandibular tooth may have been in contact in a segment. However, in one patient the heaviest contact remained on the lower right first molar for all three morning and evening recordings (Fig. 6). A ceramometal crown was present on this tooth; and although the patient could detect a deflective contact, there were no subjective symptoms. It was also noted that there was no molar contact in the Angle Class II, division 1, patient who had had maxillary first premolars removed and the maxillary anterior teeth repositioned orthodontically to improve esthetics.
DISCUSSION
1Crl7 DAY-3
MT.
SINGH
Occlusal contacts occur throughout the day and night during function as well as in parafunction. The maximum number of teeth in contact is usually found in the intercuspal position (centric occlusion).13,‘4 More recently this position of the mandible has been referred to as “the myocentric position,” as it occurs with balanced activity of jaw muscles.15Occlusal contacts in this study, therefore, were recorded in this position. Because occlusion results from the movement of the mandible activated by muscles and controlled by the nervous system,‘5-‘7factors influencing neuromuscular activity may also influence occlusal contacts. Muscle activity is also known to vary with menta12,‘* and physical stress.6,9 Mental and physical stress varies with one’s occupation and environment and is usually increased during the waking hours. Therefore, occlusal contacts may vary in number, position, and intensity throughout the day. The findings of the present investigation confirm this hypothesis and indicate that the intercuspal position does not coincide with the myocentric position throughout the day. Therefore, deflective occlusal contacts may occur in all patients. An increase in the number of diffuse occlusal contacts in the morning probably indicates muscle relaxation during the night. In contrast, the reduced number of occlusal contacts and increased number of accentuated contacts may result from increased physiologic activity of the stomatognathic system during the day. The varied location of the six heaviest contacts in the six recordings indicates that. the occlusion is partially adaptable to muscular coordination as the teeth move within the alveolus to facilitate maximum efficiency and protection. However, prolonged and severe incoordination of the mandibular muscles can result in attrition of teeth, destruction of the periodontal strucSEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY
VARIATIONS
IN OCCLUSAL
CONTACTS
20.9
20.7
16.4 ..:.:.:.:.:.: ::::j::::::: .:.:.:.:.:.:, :::::::::::::: j::::::::::: .:.:.:.:.:,:. :::::::::j:: ::::::::::::: ::::::::::::: :::::::::;::: :::::::::::::. ::::::::::::: ::::::::::::: iQ);~~~jl;; ;:;:$:;:i:; .:.:.:.:.:.:. y:::::::::: ::::::::::::: :::j::::::j i:;:;:;:;:;:; ::::::::::::: ::::::::::::: ::::::::::::: :...........
L
h
A
D A”-, t_I
pJ
MORNING
MEAN
I AY-3
DAY-2 EVENING
Fig. 3. Maximum number of teeth in contact morning and evening on 3 different days is shown for one patient.
Table II. Maximum
number
of teeth in contact Evening
Morning Patient
Day
No.
1
:!4 :!4 :! 1 214 210 18 12 13 .L‘LO Zil 210.7
1
2 3 4 5 6 7 8 9 10 Mean
t = 2.88; /J - .02 ,41< .Ol.
Day
2
24 24 17 24 20 17 18 15 26 24 20.9
Day
3
24 27 20 25 18 17 16 13 28 24 21.2
24 27 19.3 24.3 19.3 17.3 15.3 13.7 28 23 20.92
Day
16 20 16 19 18 17 18 13 2s 22 18.4
1
Dav
17 24 16 20 14 17 12 15 29 24 18.8
2
Dav
16 20 20 25 16 15 12 11 20 21 17.6
3
Mean
16.3 21.3 17.3 21.3 16 16.3 14 13 24.7 22.3 18.25
(t := 2.90) (significant). Day 1: t = 3.33 (omitting base 7); p < .Ol. Day 2: t = 2.62 (omitting base 9); p < .05. Day 3: t = 3.72;
tures, pain, muscle spasm, and organic or dysfunctional changes of the temporomandibular joint. The reduced number of occlusal contacts in the morning as opposed to the evening noted with some patients could be related to the absence of sound sleep in the presence of mental stress. Active, conscious involvement in daytime activities could overcome this stress for evening recordings. The number of occlusal contacts for the fi.rst, second, and third day, both in the morning and evening, could be related to awareness of parafunctional movements by EMG biofeedback relaxation. EMG biofeedback relaxation has been found successful in the 1:reatment of myofascial pain-dysfunction syndrome. ‘L’~ A qualitative improvement in the occlusal contacts (diffuse contacts) on subsequent THE JOURNAL
Mean
OF PROSTHETIC
DENTISTRY
mornings may also be related to the learning, through biofeedback, of progressive relaxation. The sample was too small to correlate daily variations in occlusal contacts with different types of occlusion and temporomandibular joint dysfunction. Occlusal sounds, as they have been grouped by Watt,” are the result of occlusal contacts of all types. They are dependent on the coordination of mandibular muscle activity and its relationship to the intercuspal position of the mandible. Because muscular activity is dependent on the physical state of muscle and the psychologic state of the patient, variations in these sounds are expected. Occlusal sounds can also be changed by systemic therapy, which may allow mental and/or physical relaxation. Further, these sounds can 389
BERRY AND
MORNING
SINGH
EVENING DAY-l
3.3 MEAN :::::::::::::::::::::::::i:::::~:::::,:.:.: .v.......:...:.:,:.:.:.:.:.:5.:.:.:.~ 6.6 :i:,~~::#~::~:~~~~~ :.:.:.:.:.:.> ...........................(2..
3
0
DAY . . vi.. . . . . . ...:.:.:.> . . . ...................:.:.::::::::::::$. .......C... . . .&.,.......... , 0 :::::~::::8::.~..:.::::::: :......... :.:.>>:.:.> . . . . . . . . . . . . 3 :.: .........................,A...... .............~.:.*.:.: ..............:..,...... . .,.. . ..:.:.:.:.:.:.::> i........ .. AY.:.:.:.:.:.: ...................h.. .,.....
6 y:::::::::: ::::::::::::: * .i.......%’ :::::::::::::
IT.
ulv_
w-24
F
14/D
8
TC=JO
DAY-2
:::::::..:.: .:.:.y..:.:. * >.:.:.:.:.:.: .....‘...X
DAY-3
Rr’
cl
q
ACCENTUATED
u
X=)7 lC~N&
TEETH IN CONTACT
A= ACCENTUATED
of the teeth
contacts
Evening
Patient 1 2 3 4 5 6 7 8 9 10 Total D/A % of D % of A D = Diffuse
390
Day 1
Day 2
D’ DIFFUSE
Fig. 5. Position of six heaviest contacts varies with morning and evening and day of recording.
Morning No.
TC.20
YD”
DIFFUSE
Fig. 4. Mean number of accentuated and diffuse occlusal contacts is shown for 3 days in one patient.
Table III. Diffuse/accentuated
u;
Day 3
Total D/A
Total D/A
Day 1
Day 2
Day 3
A
A
3A
A
A
3A
D
D
D
3D
A
A
D
lD/ZA
A
A
D
lD/2A
A A A
A
D
lD/ZA
D
D
D
3D
A
A
A
3A
A D A A
D A A D
D D D D
ZD/lA ZD/lA lD/2A ZD/lA
A A D A
A A A D
A A A A
3A 3A 1D/2A lD/ZA
D
D
D
3D
D
D
D
3D
A
D
D
ZD/lA
A
A
A
4D/6A
6D/4A
10D
20D/lOA
2D/BA
2D/BA
2DlBA
6D/24A
40 60
60 40
100
66.6 33.3
20 80
20 80
20 80
20 80
contacts of the teeth; A = accentuated
0
3A
contacts of the teeth.
SEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY
VARIATIONS
IN OCCLUSAL
CONTACTS
also change with the loss of myocentric occlusion because of various oral habits such as bruxism. Therefore, occlusal a.djustment of teeth to produce good sounds may noi. be the treatment of choice. Perhaps correction of the habit and care of the patient instead of the teeth may b’e the treatment of choice.zo~2’ SUMMARY
MORNING
EVENING DAY-1
AND CONCLUSION
In this study the location and severity of occlusal contacts in the morning and evening on 3 separate days were recorded for 10 women. Biofeedback therapy was used after evening recordings to encourage muscle relaxation. The findings suggest that occlusion and occlusal contacts change throughout the day and depend on the physical state of the masticatory muscles and the mental state of the patient. Although this conclusion is understandable, its effects on the philosophies of occlusal rehabilitation are questionable. Further studies are needed to evaluate the significance of the contact variations in occlusal restorations placed at different times. REFERENCES 1. Anderson, D. J., and Picton, D. C. A.: Tooth contact during chewing. J Dent Res 36~21, 1957. 2. Perry, H. T., Lammie, C. A., Main, J., and Teuscher, G. W.: Occlusion in stress situation. J Am Dent Assoc 60~626, 1960. 3. Keele, C. A., and Neil, E.: Samson Wright’s Applied Physiology, ed 12. London, 1973, Oxford University Press, p 247. 4. Green, J. H.: An Introduction to Human Physiology, ed 4. Oxford, 1978, Oxford University Press, p 180. 5. Merton, P. A : Voluntary strength and fatigue. J Physiol (Lond) 123~553, 1954. 6. Walder, D. N.: Claudication. Bristol Med Chir J 84~49, 1969. 7. Peterson, F. B., and Christenson, L. V.: Blood flow in temporal muscle during tooth grinding and clenching as measured by I33 xenon clearano:. Stand J Dent Res 81:272, 1973. 8. Rasmussen, 0. C., Petersen, F. B., Christenson, L. V., and Moller, E.: BlocadRow in human mandible elevators at rest and during controlled biting. Arch Oral Biol 22:539, 1977. 9. Christenson, L V.: Jaw muscle fatigue and pain induced by experimental trloth clenching. A review. J Oral Rehabil 8~27, 1981. IO. Kumazava, T., and Mizumura, K.: Thin fibre receptors responding to mechanical, chemical and thermal stimulation in skeletal muscle:; in the dog. J Physiol (Lond) 273~179, 1977. 1I. Alan, G. C., and Stephen, M. R.: Bruxism: A critical review, Psycho1 Bull 84,:767, 1977. 12. Berry, D. C., and Wilmot, G.: The use of biofeedback technique in the treatment of mandibular dysfunction pain, J Oral Rehabil 4255, 1977. 13. Posseh, U.: Range of movement of the mandible. J Am Dent Assoc 56:10, 1958. 14. Singh, B. P.: Centric occlusion and centric relation (retruded) position of the mandible. J Indian Dent Assoc 42131, 1970.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
‘NflOF
TEETH IN CONTACT
A= ACCENTUATED
0. DIWUSE
Fig. 6. Heaviest occlusal contact remains on mandibular right first molar in all six recordings. Note varied severity in other five contacts. 15. Jankelson, B.: Neuromuscular aspect of occlusion. Dent Clin North Am 23~157, 1979. 16. Silverman, B. I.: The physiology of occlusion. Dent Clin North Am, March 1962, p 3. 17. Ricketts, R. M.: Occlusion in the medium of dentistry. J PROSTHETDENT 21:39, 1969. 18. Yemm, R.: Variations in the electrical activity of the human masseter muscle occurring in association with emotional stress. Arch Oral Biol 14~873, 1969. 19. Gessel, A. H.: Electromyographic biofeedback and tricyclic antidepressants in myofacial pain dysfunction syndrome: Psychological predictors of outcome. J Am Dent Assoc 91:1048, 1975. 20. Watt, D. M.: Use of sounds in oral diagnosis. Proc R Sot Med 63~793, 1970. 21. Troest, T.: Diagnosing minute deflective occlusal contacts. J PROSTHETDENT 14~71, 1964.
Keprmt requ?stJto: DR. B. P. SINCH READERIN DENTISTRY BANARASHINDU UNIVERSITY VARANASI22 1005 INDIA
391
JOINT
l
OCCLUSION
EDITOR
GEORGE A. ZARB
Daily variations
in occlusal contacts
D. C. Berry, M.D.S., Ph.D.,* and B. P. Singh, M.D.S.** University of Bristol, Dental School, Bristol, England
Wl cc usa1contact of the teeth occurs during functional as well as parafunctional movements of the mandible that are sometimes related to facial or oral expressions of emotion.‘s2 These functional and parafunctional tooth contacts are influenced by the collective activity of the mandibular muscles and.are coordinated by .the peripheral and central nervous systems. Any alteration in normal muscular or neural physiology will likely have some effect on occlusal contacts. In addition to nervous system control, normal rhythmic contraction and relaxation of muscles depend on the availability of nutrients from arterial blood and removal of metabolites by venous blood.3 Availability of nutrients and fast removal of metabolites is important in muscle physiology because only a maximum of 25% of energy generated can be used for muscle contraction, while the remaining 75% is lost as heat.’ Excluding deficient cardiac output, reduced arterial flow and venous return may be due to increased intramuscular pressure during contraction.3*5 On exercise, intramuscular pressure can exceed the blood pressure and completely stop _ . arterial flo~.~ As a result oxygen debt occurs in muscles during heavy and prolonged contractile activity.7-9 Kumazava and Mizumura” have observed that the cessation of blood supply to the muscles results in complete loss of sensory impulses from muscle spindles, tendon organs, and peripheral receptors responsible for monosynaptic and polysynaptic activities in skeletal muscles. In muscles of the calf, this loss of sensory innervation results in claudication; in the lateral pterygoid muscle it may result in deviation of the mandible on opening and closing.6 The rate of venous return and clearance of metabolites is reduced during function and increased during rest. Arterial flow and the availability of nutrients are affected similarly by function and rest.8 Muscle activity, therefore, is maximum and best coordinated in the morning and reduced and less coordinated in the *Professor, University of Bristol, Dental School. **Reader in Dentistry, Banaras Hindu University, Varanasi, India; presently, Honorary Visiting Lecturer, University of Bristol, Dental School.
386
Fig. 1. Occlusal and incisal contacts are marked with articulating ribbon.
evening after the mental and physical activities of the day. For example, the walking pattern in the morning is balanced and easy while irregular and less well balanced in the evening. This variation could also be evident for muscles that control mandibular movements and, therefore, occlusal contacts. Unless one is a bruxer, there is reduced activity of the mandibular muscles at night. During the day muscle activity is increased by deglutition, conversation, expression, mastication, and bruxomania.” Therefore, it is evident that rhythmic and coordinated contraction and relaxation of mandibular muscles vary during the day, with maximum efficiency in the morning and minimum efficiency in the evening. It is reasonable to expect that occlusal contacts may also vary during the day, being at a maximum in the morning and a minimum in the evening. Perhaps the displaceability of the periodontal membrane allows enough mobility of teeth to permit maximum function throughout the day. This article will describe a study of daily variations in occlusal contacts based on this hypothesis. MATERIAL
AND METHODS
Patients for the present study were selected from dental nurse trainees at Bristol Dental School (Table
SEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY VARIATIONS
IN OCCLUSAL CONTACTS
Table I. Patient statistics
Patient No.
Age
(yrs)
Occlusion (Angle classification)
1
18
Class I
2 3 4 5 6 7 8 9
17 18
Class I Class II/ 1
18
Class I Class I Class III Class I Class III Class I Class III Class I: 6 Class II, div 1: 1 Class III: 3
10 Average
16 17 19 19 21
19 18.2
No. of teeth present 26 28 26 28 24 22 26 25 32 28 26.5
Lip competence
Orthodontic treatment
Occlusal wear
I
No
No
HC I I HC HC
No Yes No Yes Yes
No Yes No No No No
NC
Yes
HC
Yes
No
NC NC NC: 3
No Yes Yes: 6 No: 4
Yes No Yes: 2 No: 8
HC: 4 I: 3
Maximum oral opening
(mm) 45 28 50 43 42 41 45 45 40 50 42.8
TMJ Deviation of mandible No No Yes No No No No No Yes No Yes: 2 No: 8
dysfunction No Yes No No No No No No No No Yes: 1 No: 9
I = Incompetent; HC = habitually competent;and NC = naturally competent.
I). The age of the 10 women ranged from 17 to 21 years with a mean of 18.2 years. There were 22 to 32 teeth present in each patient with a mean of 26.5 teeth. The extent of dental restorations was not noted. According to Angle’s classification of maxillomandibular relationships, six were Class I; one was Class II, division 1; and three were Class III. There were naturally competent lips in three patients, habitually competent lips in four patients, and incompetent lips in three patients. Six had orthodontic treatment with or without extraction. There was no occlusal or incisal wear in eight patients, and significant occlusal and incisal wear in one patient. The average oral opening was 42.8 mm. Maximum opening varied, with a range of 40 to 50 mm at the incisors in all but one patient, in whom the opening was 28 mm. This patient developed temporomandibular joint dysfunction syndrome 3 months before the study. There was no pain or other dysfunctional symptoms in the other nine patients. Occlusal contacts were recorded with articulating paper 0.0475 tcm0.0525 mm thick while the patients were seated in a dental chair. Patients were asked to close the teeth firmly to the intercuspal position from habitual maximum opening of the jaws. The occlusal contacts were marked on each side separately (Fig. 1). The mandibuliar arch was divided into left posterior, anterior, and right posterior segments. The two most heavily colored marks in each of the three segments were recorded (Fig. 2). These marks were graded 1 to 6, depending on intensity, with 1 being the heaviest mark. The total number of marked teeth in the maxillae and the mandible was counted and recorded.
THE JOURNAL OF PROSTHETIC DENTISTRY
The occlusal contacts were classified as diffuse or accentuated according to the distribution on each tooth. One or two heavy marks on a tooth was considered accentuated, while a greater number of light marks was considered diffuse. Occlusal contacts were recorded at 9:00 AM and 4:00 PM for 3 days in a 2-week period. After 30 minutes of rest with the EMG 120 (Biofeedback Systems Ltd., Manchester, England) used for biofeedback therapy, occlusal contacts were again recorded at 4:40 PM.” Different colors of articulating paper were used to differentiate each daily recording. RESULTS Articulating paper marks on maxillary and mandibular teeth were observed morning and evening. Specific notation was made of (1) the total number of teeth in contact in both arches in the intercuspal position, (2) accentuated or diffuse contacts, and (3) the six heaviest contacts on the mandibular teeth: two each in the anterior, right posterior, and left posterior segments. Total number of teeth in contact. At most observations there were more teeth in contact in the morning than in the evening (Fig. 3, Table II). On one day an increased number of contacts was noted in the evening in three patients. The number of occlusal contacts in the morning and the evening increased in some patients on the second- and third-day observation as compared with the first day. Compared to the mean of 26.5 teeth present (Table I), the mean number of teeth in contact in the morning was found to be 20.7 on the first day, 20.9 on the second day, and 21.2 on the third day. The mean number of teeth in contact in the evening was 18.4 on
387
BERRY AND
MORNING
EVENING DAY-9
IT.
U’ULX
TC =)I+
A/O’
Tc=/C
TjD
DAY-2
IT.
u-u;
TCs/4
A/C-
u
u;
x=24 TC.NQOF
A/DTESTN IN CONTACT
TC.16 A= ACCENTUATED
Dz DIFFUSE
Fig. 2. Tooth contacts for patient No. 1 are shown for both morning and evening on 3 separate days.
the first day, 18.8 on the second day, and 17.6 on the third day. The mean number of teeth in contact for all the days was 20.92 in the morning and 18.25 in the evening, a difference of 2.67 teeth. On statistical analysis t was 2.88, which was significant at the .02 level. Accentuated or diffuse contacts. A large number of heavy or light occlusal contacts on all or most of the teeth was considered diffuse, while one or two heavy or light marks on a few teeth was considered accentuated (Fig. 4, Table III). I n most of the patients, occlusal contacts were found to be diffuse in the morning and accentuated in the evening. The number of patients with diffuse contacts in the morning increased from the first day to the second day and from the second day to the third day. Evening contacts in one patient were diffuse for all three recordings, while three patients had diffuse contacts on only one of the three evenings. In the morning 66.6% of all contacts were diffuse and 33.3% were accentuated. In the evening 80% of all contacts were accentuated and 20% were diffuse. These findings were statistically significant at the .02 level. 388
Six heaviest contacts. The six heaviest occlusal or incisal contacts, two each in the anterior, left posterior, and right posterior segments, were found to be different in the morning and the evening, and on all three recordings (Fig. 5, Table II). The sixth contact could not always be seen, as only one mandibular tooth may have been in contact in a segment. However, in one patient the heaviest contact remained on the lower right first molar for all three morning and evening recordings (Fig. 6). A ceramometal crown was present on this tooth; and although the patient could detect a deflective contact, there were no subjective symptoms. It was also noted that there was no molar contact in the Angle Class II, division 1, patient who had had maxillary first premolars removed and the maxillary anterior teeth repositioned orthodontically to improve esthetics.
DISCUSSION
1Crl7 DAY-3
MT.
SINGH
Occlusal contacts occur throughout the day and night during function as well as in parafunction. The maximum number of teeth in contact is usually found in the intercuspal position (centric occlusion).13,‘4 More recently this position of the mandible has been referred to as “the myocentric position,” as it occurs with balanced activity of jaw muscles.15Occlusal contacts in this study, therefore, were recorded in this position. Because occlusion results from the movement of the mandible activated by muscles and controlled by the nervous system,‘5-‘7factors influencing neuromuscular activity may also influence occlusal contacts. Muscle activity is also known to vary with menta12,‘* and physical stress.6,9 Mental and physical stress varies with one’s occupation and environment and is usually increased during the waking hours. Therefore, occlusal contacts may vary in number, position, and intensity throughout the day. The findings of the present investigation confirm this hypothesis and indicate that the intercuspal position does not coincide with the myocentric position throughout the day. Therefore, deflective occlusal contacts may occur in all patients. An increase in the number of diffuse occlusal contacts in the morning probably indicates muscle relaxation during the night. In contrast, the reduced number of occlusal contacts and increased number of accentuated contacts may result from increased physiologic activity of the stomatognathic system during the day. The varied location of the six heaviest contacts in the six recordings indicates that. the occlusion is partially adaptable to muscular coordination as the teeth move within the alveolus to facilitate maximum efficiency and protection. However, prolonged and severe incoordination of the mandibular muscles can result in attrition of teeth, destruction of the periodontal strucSEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY
VARIATIONS
IN OCCLUSAL
CONTACTS
20.9
20.7
16.4 ..:.:.:.:.:.: ::::j::::::: .:.:.:.:.:.:, :::::::::::::: j::::::::::: .:.:.:.:.:,:. :::::::::j:: ::::::::::::: ::::::::::::: :::::::::;::: :::::::::::::. ::::::::::::: ::::::::::::: iQ);~~~jl;; ;:;:$:;:i:; .:.:.:.:.:.:. y:::::::::: ::::::::::::: :::j::::::j i:;:;:;:;:;:; ::::::::::::: ::::::::::::: ::::::::::::: :...........
L
h
A
D A”-, t_I
pJ
MORNING
MEAN
I AY-3
DAY-2 EVENING
Fig. 3. Maximum number of teeth in contact morning and evening on 3 different days is shown for one patient.
Table II. Maximum
number
of teeth in contact Evening
Morning Patient
Day
No.
1
:!4 :!4 :! 1 214 210 18 12 13 .L‘LO Zil 210.7
1
2 3 4 5 6 7 8 9 10 Mean
t = 2.88; /J - .02 ,41< .Ol.
Day
2
24 24 17 24 20 17 18 15 26 24 20.9
Day
3
24 27 20 25 18 17 16 13 28 24 21.2
24 27 19.3 24.3 19.3 17.3 15.3 13.7 28 23 20.92
Day
16 20 16 19 18 17 18 13 2s 22 18.4
1
Dav
17 24 16 20 14 17 12 15 29 24 18.8
2
Dav
16 20 20 25 16 15 12 11 20 21 17.6
3
Mean
16.3 21.3 17.3 21.3 16 16.3 14 13 24.7 22.3 18.25
(t := 2.90) (significant). Day 1: t = 3.33 (omitting base 7); p < .Ol. Day 2: t = 2.62 (omitting base 9); p < .05. Day 3: t = 3.72;
tures, pain, muscle spasm, and organic or dysfunctional changes of the temporomandibular joint. The reduced number of occlusal contacts in the morning as opposed to the evening noted with some patients could be related to the absence of sound sleep in the presence of mental stress. Active, conscious involvement in daytime activities could overcome this stress for evening recordings. The number of occlusal contacts for the fi.rst, second, and third day, both in the morning and evening, could be related to awareness of parafunctional movements by EMG biofeedback relaxation. EMG biofeedback relaxation has been found successful in the 1:reatment of myofascial pain-dysfunction syndrome. ‘L’~ A qualitative improvement in the occlusal contacts (diffuse contacts) on subsequent THE JOURNAL
Mean
OF PROSTHETIC
DENTISTRY
mornings may also be related to the learning, through biofeedback, of progressive relaxation. The sample was too small to correlate daily variations in occlusal contacts with different types of occlusion and temporomandibular joint dysfunction. Occlusal sounds, as they have been grouped by Watt,” are the result of occlusal contacts of all types. They are dependent on the coordination of mandibular muscle activity and its relationship to the intercuspal position of the mandible. Because muscular activity is dependent on the physical state of muscle and the psychologic state of the patient, variations in these sounds are expected. Occlusal sounds can also be changed by systemic therapy, which may allow mental and/or physical relaxation. Further, these sounds can 389
BERRY AND
MORNING
SINGH
EVENING DAY-l
3.3 MEAN :::::::::::::::::::::::::i:::::~:::::,:.:.: .v.......:...:.:,:.:.:.:.:.:5.:.:.:.~ 6.6 :i:,~~::#~::~:~~~~~ :.:.:.:.:.:.> ...........................(2..
3
0
DAY . . vi.. . . . . . ...:.:.:.> . . . ...................:.:.::::::::::::$. .......C... . . .&.,.......... , 0 :::::~::::8::.~..:.::::::: :......... :.:.>>:.:.> . . . . . . . . . . . . 3 :.: .........................,A...... .............~.:.*.:.: ..............:..,...... . .,.. . ..:.:.:.:.:.:.::> i........ .. AY.:.:.:.:.:.: ...................h.. .,.....
6 y:::::::::: ::::::::::::: * .i.......%’ :::::::::::::
IT.
ulv_
w-24
F
14/D
8
TC=JO
DAY-2
:::::::..:.: .:.:.y..:.:. * >.:.:.:.:.:.: .....‘...X
DAY-3
Rr’
cl
q
ACCENTUATED
u
X=)7 lC~N&
TEETH IN CONTACT
A= ACCENTUATED
of the teeth
contacts
Evening
Patient 1 2 3 4 5 6 7 8 9 10 Total D/A % of D % of A D = Diffuse
390
Day 1
Day 2
D’ DIFFUSE
Fig. 5. Position of six heaviest contacts varies with morning and evening and day of recording.
Morning No.
TC.20
YD”
DIFFUSE
Fig. 4. Mean number of accentuated and diffuse occlusal contacts is shown for 3 days in one patient.
Table III. Diffuse/accentuated
u;
Day 3
Total D/A
Total D/A
Day 1
Day 2
Day 3
A
A
3A
A
A
3A
D
D
D
3D
A
A
D
lD/ZA
A
A
D
lD/2A
A A A
A
D
lD/ZA
D
D
D
3D
A
A
A
3A
A D A A
D A A D
D D D D
ZD/lA ZD/lA lD/2A ZD/lA
A A D A
A A A D
A A A A
3A 3A 1D/2A lD/ZA
D
D
D
3D
D
D
D
3D
A
D
D
ZD/lA
A
A
A
4D/6A
6D/4A
10D
20D/lOA
2D/BA
2D/BA
2DlBA
6D/24A
40 60
60 40
100
66.6 33.3
20 80
20 80
20 80
20 80
contacts of the teeth; A = accentuated
0
3A
contacts of the teeth.
SEPTEMBER
1983
VOLUME
50
NUMBER
3
DAILY
VARIATIONS
IN OCCLUSAL
CONTACTS
also change with the loss of myocentric occlusion because of various oral habits such as bruxism. Therefore, occlusal a.djustment of teeth to produce good sounds may noi. be the treatment of choice. Perhaps correction of the habit and care of the patient instead of the teeth may b’e the treatment of choice.zo~2’ SUMMARY
MORNING
EVENING DAY-1
AND CONCLUSION
In this study the location and severity of occlusal contacts in the morning and evening on 3 separate days were recorded for 10 women. Biofeedback therapy was used after evening recordings to encourage muscle relaxation. The findings suggest that occlusion and occlusal contacts change throughout the day and depend on the physical state of the masticatory muscles and the mental state of the patient. Although this conclusion is understandable, its effects on the philosophies of occlusal rehabilitation are questionable. Further studies are needed to evaluate the significance of the contact variations in occlusal restorations placed at different times. REFERENCES 1. Anderson, D. J., and Picton, D. C. A.: Tooth contact during chewing. J Dent Res 36~21, 1957. 2. Perry, H. T., Lammie, C. A., Main, J., and Teuscher, G. W.: Occlusion in stress situation. J Am Dent Assoc 60~626, 1960. 3. Keele, C. A., and Neil, E.: Samson Wright’s Applied Physiology, ed 12. London, 1973, Oxford University Press, p 247. 4. Green, J. H.: An Introduction to Human Physiology, ed 4. Oxford, 1978, Oxford University Press, p 180. 5. Merton, P. A : Voluntary strength and fatigue. J Physiol (Lond) 123~553, 1954. 6. Walder, D. N.: Claudication. Bristol Med Chir J 84~49, 1969. 7. Peterson, F. B., and Christenson, L. V.: Blood flow in temporal muscle during tooth grinding and clenching as measured by I33 xenon clearano:. Stand J Dent Res 81:272, 1973. 8. Rasmussen, 0. C., Petersen, F. B., Christenson, L. V., and Moller, E.: BlocadRow in human mandible elevators at rest and during controlled biting. Arch Oral Biol 22:539, 1977. 9. Christenson, L V.: Jaw muscle fatigue and pain induced by experimental trloth clenching. A review. J Oral Rehabil 8~27, 1981. IO. Kumazava, T., and Mizumura, K.: Thin fibre receptors responding to mechanical, chemical and thermal stimulation in skeletal muscle:; in the dog. J Physiol (Lond) 273~179, 1977. 1I. Alan, G. C., and Stephen, M. R.: Bruxism: A critical review, Psycho1 Bull 84,:767, 1977. 12. Berry, D. C., and Wilmot, G.: The use of biofeedback technique in the treatment of mandibular dysfunction pain, J Oral Rehabil 4255, 1977. 13. Posseh, U.: Range of movement of the mandible. J Am Dent Assoc 56:10, 1958. 14. Singh, B. P.: Centric occlusion and centric relation (retruded) position of the mandible. J Indian Dent Assoc 42131, 1970.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
‘NflOF
TEETH IN CONTACT
A= ACCENTUATED
0. DIWUSE
Fig. 6. Heaviest occlusal contact remains on mandibular right first molar in all six recordings. Note varied severity in other five contacts. 15. Jankelson, B.: Neuromuscular aspect of occlusion. Dent Clin North Am 23~157, 1979. 16. Silverman, B. I.: The physiology of occlusion. Dent Clin North Am, March 1962, p 3. 17. Ricketts, R. M.: Occlusion in the medium of dentistry. J PROSTHETDENT 21:39, 1969. 18. Yemm, R.: Variations in the electrical activity of the human masseter muscle occurring in association with emotional stress. Arch Oral Biol 14~873, 1969. 19. Gessel, A. H.: Electromyographic biofeedback and tricyclic antidepressants in myofacial pain dysfunction syndrome: Psychological predictors of outcome. J Am Dent Assoc 91:1048, 1975. 20. Watt, D. M.: Use of sounds in oral diagnosis. Proc R Sot Med 63~793, 1970. 21. Troest, T.: Diagnosing minute deflective occlusal contacts. J PROSTHETDENT 14~71, 1964.
Keprmt requ?stJto: DR. B. P. SINCH READERIN DENTISTRY BANARASHINDU UNIVERSITY VARANASI22 1005 INDIA
391