Journal of Oral Rehabilitation, 1991, Volume 18, pages 453-458
Occlusal abnormalities, pericranial muscle and joint tenderness and tooth wear in a group of migraine patients J . G . STEELE, P.J. LAMEY*, S.W. S H A R K E Y t and G .M c R . SMITH t Department of Operative Dentistry, Newurrtle upon Tyne Dental School, Newcastle upon Tyne, and *Department of Oral Medicine and Pathology and fDepartnunt of Conservative Dentisiry, Glasgow Dental School, Glasgow, U.K.
Summary
Seventy-two migraine sufferers, whose attacks normally begin during or soon after waking from sleep, were compared with 37 age- and sex-matched controls to establish whether signs of mandibular dysfunction, occlusal discrepanciesand known clenching or grinding habits were any more frequent among the former group. Temporomandibular joint tenderness or pain history, masticatory muscle tenderness and known clenching or grinding habits were found to occur at significantly increased levels in the migraine sufferers, with two-thirds of these patients reporting a parafunctional habit. Occlusal abnormalities, including non-working side or protrusive interferences and slides of > 1mm to the intercuspal position, were found to occur at similar frequencies in the two groups. Assessment of wear of the occlusal surfaces also showed no difference, suggesting that any nocturnal habit with a role in migraine is more likely to be clenching in nature. In conclusion, evidence was found to support an aetiological role for nocturnal tooth clenching or grinding in migraine characterized by attacks that start predominantly during sleep or soon after waking, but no evidence of a link with occlusal factors was found in these patients. Introduction Migraine is a muitifactorial disease. Scientific evidence of dental involvement in migraine is scarce, and much of what has been written in non-refereed journals or books may be applicable to temporomandibular dysfunction (TMD)or tension type headaches (Watts, Peet & Juniper, 1986), and not to migraine as defined by the latest international criteria. However, one study has claimed a reduction in the frequency of migraine attacks with occlusal treatment in a selected group of migraine patients in whom attacks predominantly occurred on waking or shortly thereafter ( b e y & Barclay, 1987). The timing of these attacks of migraine is indicative of the involvement of a nocturnal parafunctional habit as a possible trigger factor in susceptible individuals. The present study was therefore undertaken in order to assess some of the oral and dental aspects of patients who experience migraine on waking: first, a clinical assessment Correspondence: J.G.Steele, Department of Operative Dentistry, Newcastle upon Tyne Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW, U.K.
453
454
J.G. Steele et al.
of pericranial muscle and temporomandibular joint tenderness; secondly, functional occlud analysis; and thirdly, static analysis of patient models in relation to tooth wear. The aims of the study were to investigate whether there was any evidence to link parafunctional habits, occlusal interference and tooth wear with migraine. Materials and methods All migraine patients were referred, directly or indirectly, by their general medical practitioners to the Glasgow Oral Medicine Clinic. This pattern of referral reflects the longstanding interest of the Unit in facial pain and headache of various aetiologies. Seventy-two patients with migraine (with or without aura) were examined in order to assess the frequency of static and dynamic occlusal abnormalities and tenderness of the masticatory apparatus. The migraine group consisted of 51 women (mean age 38-8 years, range 17-59 years) and 21 men (mean age 36.4 years, range 12-69 years). All migraine patients were dentate and fulfilled the following criteria. (i) Symptoms and history of migraine fulfilled the present criteria for the diagnosis of migraine with or without aura (Olsen, 1988), and not any other condition which is characterized by headache. Where a history or symptoms of TMD were present, these patients were still coded as having migraine, to reflect their primary complaint. (ii) More than 50% of attacks occurred on waking from sleep, or followed an aura which was present on waking. (iii) All patients were dentate or partially dentate and could achieve an intercuspal relationship without any removable prostheses in sihc. The control group consisted of 22 women (mean age 38.8 years) and 9 men (mean age 35-8years) who were randomly recruited from diagnosis and treatment clinics within Glasgow Dental Hospital. All patients were sex- and age-matched, the latter according to 5-year groupings. No controls were current migraine sufferers, and all were dentate and could achieve an intercuspal relationship without the aid of a partial denture. A full history was taken, which conformed to a standard pattern for all patients, covering headache, symptoms of TMD or joint pain and general medical and dental histories. A detailed dental and oro-facial examination was undertaken for each patient, and alginate impressions were recorded, their casts poured in stone and retained. All clinical examinations were performed blind by the same clinician. The extra-oral examination consisted of bilateral palpation of temporalis and masseter muscles for general tenderness and trigger points, and of the temporomandibular joint for tenderness or pain, and examination of the functioning mandible and joint in order to detect deviation of the mandible and the presence or otherwise of TMJ clicks or crepitus. Intra-orally the pterygoid muscles were palpated, but no attempt was made to differentiate between medial and lateral pterygoid muscles due to the inherent uncertainty of identification of the exacf source of tenderness in this area (Johnstone & Templeton, 1980). Muscles were scored as 0 or 1 depending on whether or not tenderness was detected by gentle digital palpation. The degree of posterior support was assessed by enumerating the number of posterior teeth in contact, and the incisor relationship was noted (Angle’s classification). Aspects of the dynamic occlusion were then examined. Occlusal guidance (canine or group function) in the right and left lateral excursions was recorded using GHM tape*, and all non-working side contacts were noted after checking with 8-micron
* GHM-Hanel-Medizinal, D-7440 Nurtingen, Germany.
Occlusal factors and migraine
455
shimstock*. Transient non-working side contacts were distinguished from non-working side interferences (where there is disruption of the working side guidance by the nonworking side contacts). All premature contacts on the retruded hinge axis with horizontal or lateral slides of > lmm to the intercuspal position were recorded. The presence of posterior tooth interferences in protrusive excursions was noted. Interferences and prematurities were scored as either present or absent, and were not quantified further. Guidance was assigned to either canine or group function, and for statistical purposes the left and right sides were treated separately. The patients’ casts were examined by two of the authors independently. The occlusal tooth surface wear was scored for each patient using the system reported by Smith and Knight (1984). All data, except those relating to tooth wear, were categorical in nature, and statistical analysis of the frequency differences between the two samples was performed by Chi-squared tests. The tooth wear data were analysed using an unpaired t-test. RWults By design there were no differences in sex or mean age of the migraine patients compared to the control subjects. In both groups masticatory muscle tenderness was sought, and the proportion of patients that exhibited unilateral or bilateral tenderness was recorded (Table 1). However, the small number of control patients affected in this respect could serve to exaggerate any differences. The difference in frequency of muscle tenderness was found to be statistically significantat the 0-05 level of probability for masseter and pterygoid groups, and at the 0.001 level for temporalis. Statistically significant differences between the groups were also found when TMJ pain history or tenderness, mandibular deviation and known clenching or bruxist habits were analysed. The difference in the latter category is particularly interesting as it may be a significantaetiological factor in migraine. However, since patients were questioned about any parafunctional habits, there may have been some distortion due to a heightened awareness by some sufferers of the possible importance of parafunctional habits in their condition. Both non-working side contacts and non-working side interferences were found at
Table 1. Muscle tenderness, joint pain or history, deviation and bruxism/clenching Migraine (“7) ( n = 72)
Control (96) (n = 37)
P-value
Tenderness Temporalis Masseter Pterygoid
43 29 58
3 10 35
< 0.001 < 0.05 < 0.05
Joint paidhistory
39
10
< 0.01
Mandibular deviation
31
10
< 0.05
Bruxismklenching
67
32
< 0.01
* GHM-Hanel-Medizinal, D-7440 Nurtingen, Germany.
456
J.G. Sreele et al.
a higher frequency in the control group (Table 2), but this difference was not significant at the 0.05 level of probability. When classification of the type of occlusion (Angle’s classification) or the presence of canine guidance or group function was analysed, no significant difference could be found. There was a marked difference between the groups when slides of >lmm from the retruded contact position to the intercuspal position were recorded but, again, this was found to be statistically nonsignificant at the 0.05 level of probability. Tooth wear analysis did not reveal a significantly higher occlusal tooth surface loss from the control group (Table 3), although 67% of the migraine group reported a clenching or grinding habit (Table 1). Discussion All the patients in this study suffered from symptoms indicative of migraine with or without aura, according to current diagnostic criteria (Olesen, 1988). Relationships between mandibular dysfunction and headache have been widely reported (Wanman & Agerberg, 1986), but evidence for a link between mandibular dysfunction and diagnosed migraine is scarce. Circumstantial evidence to suggest that such relationships exist comes from published reports of successful splint therapy in patients who suffer from migraine attacks on waking (Lamey & Barclay, 1987), and claims of the success of occlusal adjustment in migraneurs (Higson, 1985). Such interocclusal appliances are widely used for the management of temporomandibular dysfunction (Clark, 1984a, b), and have been shown to be effective in some migraine sufferers (Lamey & Barclay, 1987). The mode of action of occlusal splints in both of these disorders remains uncertain, but the successful response in migraine sufferers may indicate that mandibular dysfunction plays a role in some patients. In addition to this circumstantial evidence, signs of mandibular dysfunction have been reported at increased frequency in migraine sufferers. Lous and Olsen (1982) analysed a mixed group of migraine, muscle contraction headache and combination (migraine and muscle contraction) headache patients and demonstrated tenderness of the masticatory muscles in most of these individuals, although the total number of patients in each group was rather small. Electromyographic and blood flow studies have also demonstrated changes in the temporal muscles with migraine attacks (Bakke
Table 2. Aspects of dynamic occlusion Migraine (%)
Control (%) (n = 37)
P-value
(n=72)
Slide > 1 mm (lateral or protrusive)
42
26
NS
Non-working side contacts
38
45
NS
Non-working side interference
17
23
NS
Protrusive interference
15
26
NS
Occlusal factors and migraine
457
Table 3. Occlusal wear index
Surfaces examined Tooth wear index
Migraine
Control
12.7 f 3.7 8.2 f 4.6
12.5 f 5-0 7.6f 3.8
Mean values -t SD are shown.
er al., 1982; Clifford et al., 1982; Jensen & Olesen, 1985). The present study showed a marked differencein temporalis, masseter and pterygoid tendernessbetween migraneurs and controls, in agreement with previous work (Lous & Olsen, 1982), although unlike the latter study, signs of tenderness in the masticatory muscles of the normal controls were not uncommon. The presence of such inter-group differences strongly supports previous suggestions of a role for masticatory muscle activity, or hyperactivity, in migraine. Whether this acts as a trigger factor or is secondary to the migraine pain is still uncertain. The reported frequency of brwist and clenching habits was significantly higher among the migraineurs, with a known habit present in more than two-thirds of patients, and this figure obviously does not include habitual clenchers, who are unaware of their clenching or bruxist tendency. Such habits were again reported surprisingly frequently among the controls. A high frequency of reported parafunctional habits has been reported in previous studies of headache, including some studies of migraine sufferers (Lous & Olsen, 1982; Wanman & Agerberg, 1986; Moss et af., 1988). Taken in conjunction with the tooth wear analysis, this frequency of reported habits was very interesting. The overall levels of attrition reported did not differ from physiological levels of wear in the general population. It is therefore suggested that any habits that may be linked with waking migraine are more likely to be of a clenching type, with minimal lateral or protrusive excursive movements, rather than excursive bruxism, which is likely to result in more extensive attrition of the dental tissues. A relationship between tooth clenching and migraine was examined by Jensen, Bulow and Hansen (1985), who investigated 'the result of experimental tooth clenching in a group of migraine sufferers. They found no significant increase in migraine attacks following the experiment, although an increase in non-migranous headaches was reported, but there was no indication that the patients were likely to have experienced attacks related to a clenching habit. The present study included only waking sufferers, and the results strongly suggest that a clenching habit is a common and probably important feature in this type of patient. Aspects of static and dynamic occlusion showed no significant differences between the groups. A marked increase in slides of > 1mm from RCP to ICP was noted among the migraineurs, but this was not found to be significant at the 0-05level of probability. There was no significant difference when other clinical parameters were measured. Some practitioners recommend occlusal adjustment or equilibration for migraine sufferers (Higson, 1985; Cawley, 1988). Such treatment is more widely advocated for temporomandibular dysfunction,and this topic has been thoroughly discussed previously (Wassell, 1989). Forsell, Kirveskari and Kangasniemi (1985) investigated the effect of occlusal adjustment on a group of headache sufferers, including some combination
458
J.G. Steele et al.
headache and migraine patients. They observed some benefit to the former group, but no apparent benefit to the migraneurs. The present study showed that the occlusal ‘abnormalities’that may be therapeutically adjusted were no more common in sufferers from waking migraine than in matched controls. Clearly this does not preclude a role for such ‘abnormalities’in the aetiology of migraine in patients who, for some reason, are more vulnerable to the possible disruptive effects of their occlusion. However, if such patients exist, their identification is almost impossible, and the results of this study may lend support to the suggestion that any oral or masticatory contribution to the aetiology of migraine is not wholly occlusal in nature. Acknowledgements The authors would like to thank the Department of Medical Statistics of the University of Glasgow for help and advice with the statistical analyses. References BAKKE,M.,TPBLT-HANSEN, P., OLFSEN,J.
& MOLLER,E. (1982) Action of some pencranial muscles during provoked attacks of common migraine. Pain, 14, 21. CAWLEY, R. (1988) Treatment of TMJ dysfunction. Dental Practice, 26, 1. CLARK,G.T. (1984a) A critical evaluation of orthopedic inter-occlusal appliance therapy: design, theory and overall effectiveness. Journal of the American Dental Association, 108, 359. CLARK, G.T. (1984b) A critical evaluation of orthopedic inter-occlusal appliance therapy: effectiveness for specific symptoms. Journal of the American Dental Association, 108, 364. CLWORD,T., L A u a r r z ~ ~M., , B m , M. & OLESEN, J. (1982) Electromyography of pericranial muscles during treatment of spontaneous common migraine attacks. Pain, 14, 137. FORSSELL, H., KIRVESKARI,P. & KANGASNCBW, P. (1985) Changes in headache after treatment of mandibular dysfunction. Cephalagia, 5 , 229. HIGSON, R. (1985) Treatment of migraine and associated conditions through dental treatment. The 1985 Dental Annual, p. 73. John Wright and Sons, Bristol. JENSEN, K. & OLESEN, J. (1985) Temporal muscle blood flow in common migraine. Acta Neurologica Scandinavica, 72, 561. JENSEN, K., BULOW,P. & HANSEN,H. (1985) Experimental toothclenching in common migraine. Cephahgia, 5, 245. JOHNSTONE, D.R. & Templeton, M. (1980) The feasibility of palpating the lateral pterygoid muscle. Journal of Prosthetic Dentistry, 44, 318. LAMEY, P.-J. & BARCLAY, S.C. (1987) Clinical effectiveness of occlusal splint therapy in patients with classical migraine. Sconish Medical Journal, 32, 11. LOWS,I. & OLESEN,J. (1982) Evaluation of pericranial tenderness and oral function in patients with common migraine, muscle contraction headache and combination headache. Pain, 12, 385. Moss, R.A., L~MBARDO, T.W., VILMOSA,G.A., HODGSON, J.M., O’CARROLL, M., COOLBY, J.E. & SMITH, P. (1988) Ongoing assessments of oral habits in common migraine and non-headache populations. Journal of Craniomandibular Practice, 6, 352. OMEN,J. (1988) Classification and diagnostic criteria for headache disorders, cranial neuralgias and facial pain. Cephalagia, 8 (Suppl. 7), 19. S m , B.G.N.& KNIGHT,J.K. (1984) An index for measuring the wear of teeth. British Dental Journal, 156, 435. WANMAN, A. & AGERBERG, G. (1986) Headache and dysfunctionof the masticatory system in adolescents. Cephalagia, 6, 247. WASSELL,R.W.W. (1989) Do occlusal factors play a part in temporomandibulardysfunction? Journal of Dentistry, 17, 101. WAITS,P.G., PEW, K.M.S. & JUNIPER, R.P. (1986) Migraine and the temporomandibular joint: the final answer? British Dental Journal, 161, 170.
Occlusal abnormalities, pericranial muscle and joint tenderness and tooth wear in a group of migraine patients J . G . STEELE, P.J. LAMEY*, S.W. S H A R K E Y t and G .M c R . SMITH t Department of Operative Dentistry, Newurrtle upon Tyne Dental School, Newcastle upon Tyne, and *Department of Oral Medicine and Pathology and fDepartnunt of Conservative Dentisiry, Glasgow Dental School, Glasgow, U.K.
Summary
Seventy-two migraine sufferers, whose attacks normally begin during or soon after waking from sleep, were compared with 37 age- and sex-matched controls to establish whether signs of mandibular dysfunction, occlusal discrepanciesand known clenching or grinding habits were any more frequent among the former group. Temporomandibular joint tenderness or pain history, masticatory muscle tenderness and known clenching or grinding habits were found to occur at significantly increased levels in the migraine sufferers, with two-thirds of these patients reporting a parafunctional habit. Occlusal abnormalities, including non-working side or protrusive interferences and slides of > 1mm to the intercuspal position, were found to occur at similar frequencies in the two groups. Assessment of wear of the occlusal surfaces also showed no difference, suggesting that any nocturnal habit with a role in migraine is more likely to be clenching in nature. In conclusion, evidence was found to support an aetiological role for nocturnal tooth clenching or grinding in migraine characterized by attacks that start predominantly during sleep or soon after waking, but no evidence of a link with occlusal factors was found in these patients. Introduction Migraine is a muitifactorial disease. Scientific evidence of dental involvement in migraine is scarce, and much of what has been written in non-refereed journals or books may be applicable to temporomandibular dysfunction (TMD)or tension type headaches (Watts, Peet & Juniper, 1986), and not to migraine as defined by the latest international criteria. However, one study has claimed a reduction in the frequency of migraine attacks with occlusal treatment in a selected group of migraine patients in whom attacks predominantly occurred on waking or shortly thereafter ( b e y & Barclay, 1987). The timing of these attacks of migraine is indicative of the involvement of a nocturnal parafunctional habit as a possible trigger factor in susceptible individuals. The present study was therefore undertaken in order to assess some of the oral and dental aspects of patients who experience migraine on waking: first, a clinical assessment Correspondence: J.G.Steele, Department of Operative Dentistry, Newcastle upon Tyne Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW, U.K.
453
454
J.G. Steele et al.
of pericranial muscle and temporomandibular joint tenderness; secondly, functional occlud analysis; and thirdly, static analysis of patient models in relation to tooth wear. The aims of the study were to investigate whether there was any evidence to link parafunctional habits, occlusal interference and tooth wear with migraine. Materials and methods All migraine patients were referred, directly or indirectly, by their general medical practitioners to the Glasgow Oral Medicine Clinic. This pattern of referral reflects the longstanding interest of the Unit in facial pain and headache of various aetiologies. Seventy-two patients with migraine (with or without aura) were examined in order to assess the frequency of static and dynamic occlusal abnormalities and tenderness of the masticatory apparatus. The migraine group consisted of 51 women (mean age 38-8 years, range 17-59 years) and 21 men (mean age 36.4 years, range 12-69 years). All migraine patients were dentate and fulfilled the following criteria. (i) Symptoms and history of migraine fulfilled the present criteria for the diagnosis of migraine with or without aura (Olsen, 1988), and not any other condition which is characterized by headache. Where a history or symptoms of TMD were present, these patients were still coded as having migraine, to reflect their primary complaint. (ii) More than 50% of attacks occurred on waking from sleep, or followed an aura which was present on waking. (iii) All patients were dentate or partially dentate and could achieve an intercuspal relationship without any removable prostheses in sihc. The control group consisted of 22 women (mean age 38.8 years) and 9 men (mean age 35-8years) who were randomly recruited from diagnosis and treatment clinics within Glasgow Dental Hospital. All patients were sex- and age-matched, the latter according to 5-year groupings. No controls were current migraine sufferers, and all were dentate and could achieve an intercuspal relationship without the aid of a partial denture. A full history was taken, which conformed to a standard pattern for all patients, covering headache, symptoms of TMD or joint pain and general medical and dental histories. A detailed dental and oro-facial examination was undertaken for each patient, and alginate impressions were recorded, their casts poured in stone and retained. All clinical examinations were performed blind by the same clinician. The extra-oral examination consisted of bilateral palpation of temporalis and masseter muscles for general tenderness and trigger points, and of the temporomandibular joint for tenderness or pain, and examination of the functioning mandible and joint in order to detect deviation of the mandible and the presence or otherwise of TMJ clicks or crepitus. Intra-orally the pterygoid muscles were palpated, but no attempt was made to differentiate between medial and lateral pterygoid muscles due to the inherent uncertainty of identification of the exacf source of tenderness in this area (Johnstone & Templeton, 1980). Muscles were scored as 0 or 1 depending on whether or not tenderness was detected by gentle digital palpation. The degree of posterior support was assessed by enumerating the number of posterior teeth in contact, and the incisor relationship was noted (Angle’s classification). Aspects of the dynamic occlusion were then examined. Occlusal guidance (canine or group function) in the right and left lateral excursions was recorded using GHM tape*, and all non-working side contacts were noted after checking with 8-micron
* GHM-Hanel-Medizinal, D-7440 Nurtingen, Germany.
Occlusal factors and migraine
455
shimstock*. Transient non-working side contacts were distinguished from non-working side interferences (where there is disruption of the working side guidance by the nonworking side contacts). All premature contacts on the retruded hinge axis with horizontal or lateral slides of > lmm to the intercuspal position were recorded. The presence of posterior tooth interferences in protrusive excursions was noted. Interferences and prematurities were scored as either present or absent, and were not quantified further. Guidance was assigned to either canine or group function, and for statistical purposes the left and right sides were treated separately. The patients’ casts were examined by two of the authors independently. The occlusal tooth surface wear was scored for each patient using the system reported by Smith and Knight (1984). All data, except those relating to tooth wear, were categorical in nature, and statistical analysis of the frequency differences between the two samples was performed by Chi-squared tests. The tooth wear data were analysed using an unpaired t-test. RWults By design there were no differences in sex or mean age of the migraine patients compared to the control subjects. In both groups masticatory muscle tenderness was sought, and the proportion of patients that exhibited unilateral or bilateral tenderness was recorded (Table 1). However, the small number of control patients affected in this respect could serve to exaggerate any differences. The difference in frequency of muscle tenderness was found to be statistically significantat the 0-05 level of probability for masseter and pterygoid groups, and at the 0.001 level for temporalis. Statistically significant differences between the groups were also found when TMJ pain history or tenderness, mandibular deviation and known clenching or bruxist habits were analysed. The difference in the latter category is particularly interesting as it may be a significantaetiological factor in migraine. However, since patients were questioned about any parafunctional habits, there may have been some distortion due to a heightened awareness by some sufferers of the possible importance of parafunctional habits in their condition. Both non-working side contacts and non-working side interferences were found at
Table 1. Muscle tenderness, joint pain or history, deviation and bruxism/clenching Migraine (“7) ( n = 72)
Control (96) (n = 37)
P-value
Tenderness Temporalis Masseter Pterygoid
43 29 58
3 10 35
< 0.001 < 0.05 < 0.05
Joint paidhistory
39
10
< 0.01
Mandibular deviation
31
10
< 0.05
Bruxismklenching
67
32
< 0.01
* GHM-Hanel-Medizinal, D-7440 Nurtingen, Germany.
456
J.G. Sreele et al.
a higher frequency in the control group (Table 2), but this difference was not significant at the 0.05 level of probability. When classification of the type of occlusion (Angle’s classification) or the presence of canine guidance or group function was analysed, no significant difference could be found. There was a marked difference between the groups when slides of >lmm from the retruded contact position to the intercuspal position were recorded but, again, this was found to be statistically nonsignificant at the 0.05 level of probability. Tooth wear analysis did not reveal a significantly higher occlusal tooth surface loss from the control group (Table 3), although 67% of the migraine group reported a clenching or grinding habit (Table 1). Discussion All the patients in this study suffered from symptoms indicative of migraine with or without aura, according to current diagnostic criteria (Olesen, 1988). Relationships between mandibular dysfunction and headache have been widely reported (Wanman & Agerberg, 1986), but evidence for a link between mandibular dysfunction and diagnosed migraine is scarce. Circumstantial evidence to suggest that such relationships exist comes from published reports of successful splint therapy in patients who suffer from migraine attacks on waking (Lamey & Barclay, 1987), and claims of the success of occlusal adjustment in migraneurs (Higson, 1985). Such interocclusal appliances are widely used for the management of temporomandibular dysfunction (Clark, 1984a, b), and have been shown to be effective in some migraine sufferers (Lamey & Barclay, 1987). The mode of action of occlusal splints in both of these disorders remains uncertain, but the successful response in migraine sufferers may indicate that mandibular dysfunction plays a role in some patients. In addition to this circumstantial evidence, signs of mandibular dysfunction have been reported at increased frequency in migraine sufferers. Lous and Olsen (1982) analysed a mixed group of migraine, muscle contraction headache and combination (migraine and muscle contraction) headache patients and demonstrated tenderness of the masticatory muscles in most of these individuals, although the total number of patients in each group was rather small. Electromyographic and blood flow studies have also demonstrated changes in the temporal muscles with migraine attacks (Bakke
Table 2. Aspects of dynamic occlusion Migraine (%)
Control (%) (n = 37)
P-value
(n=72)
Slide > 1 mm (lateral or protrusive)
42
26
NS
Non-working side contacts
38
45
NS
Non-working side interference
17
23
NS
Protrusive interference
15
26
NS
Occlusal factors and migraine
457
Table 3. Occlusal wear index
Surfaces examined Tooth wear index
Migraine
Control
12.7 f 3.7 8.2 f 4.6
12.5 f 5-0 7.6f 3.8
Mean values -t SD are shown.
er al., 1982; Clifford et al., 1982; Jensen & Olesen, 1985). The present study showed a marked differencein temporalis, masseter and pterygoid tendernessbetween migraneurs and controls, in agreement with previous work (Lous & Olsen, 1982), although unlike the latter study, signs of tenderness in the masticatory muscles of the normal controls were not uncommon. The presence of such inter-group differences strongly supports previous suggestions of a role for masticatory muscle activity, or hyperactivity, in migraine. Whether this acts as a trigger factor or is secondary to the migraine pain is still uncertain. The reported frequency of brwist and clenching habits was significantly higher among the migraineurs, with a known habit present in more than two-thirds of patients, and this figure obviously does not include habitual clenchers, who are unaware of their clenching or bruxist tendency. Such habits were again reported surprisingly frequently among the controls. A high frequency of reported parafunctional habits has been reported in previous studies of headache, including some studies of migraine sufferers (Lous & Olsen, 1982; Wanman & Agerberg, 1986; Moss et af., 1988). Taken in conjunction with the tooth wear analysis, this frequency of reported habits was very interesting. The overall levels of attrition reported did not differ from physiological levels of wear in the general population. It is therefore suggested that any habits that may be linked with waking migraine are more likely to be of a clenching type, with minimal lateral or protrusive excursive movements, rather than excursive bruxism, which is likely to result in more extensive attrition of the dental tissues. A relationship between tooth clenching and migraine was examined by Jensen, Bulow and Hansen (1985), who investigated 'the result of experimental tooth clenching in a group of migraine sufferers. They found no significant increase in migraine attacks following the experiment, although an increase in non-migranous headaches was reported, but there was no indication that the patients were likely to have experienced attacks related to a clenching habit. The present study included only waking sufferers, and the results strongly suggest that a clenching habit is a common and probably important feature in this type of patient. Aspects of static and dynamic occlusion showed no significant differences between the groups. A marked increase in slides of > 1mm from RCP to ICP was noted among the migraineurs, but this was not found to be significant at the 0-05level of probability. There was no significant difference when other clinical parameters were measured. Some practitioners recommend occlusal adjustment or equilibration for migraine sufferers (Higson, 1985; Cawley, 1988). Such treatment is more widely advocated for temporomandibular dysfunction,and this topic has been thoroughly discussed previously (Wassell, 1989). Forsell, Kirveskari and Kangasniemi (1985) investigated the effect of occlusal adjustment on a group of headache sufferers, including some combination
458
J.G. Steele et al.
headache and migraine patients. They observed some benefit to the former group, but no apparent benefit to the migraneurs. The present study showed that the occlusal ‘abnormalities’that may be therapeutically adjusted were no more common in sufferers from waking migraine than in matched controls. Clearly this does not preclude a role for such ‘abnormalities’in the aetiology of migraine in patients who, for some reason, are more vulnerable to the possible disruptive effects of their occlusion. However, if such patients exist, their identification is almost impossible, and the results of this study may lend support to the suggestion that any oral or masticatory contribution to the aetiology of migraine is not wholly occlusal in nature. Acknowledgements The authors would like to thank the Department of Medical Statistics of the University of Glasgow for help and advice with the statistical analyses. References BAKKE,M.,TPBLT-HANSEN, P., OLFSEN,J.
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