The aims of this study were (1) to investigate the relationship between occlusal factors and masticatory muscle tenderness among 10- to 19-year-old (mean 14 years eight months) Turkish subjects and (2) to identify possible sex differences between them. The sample consisted of 716 individuals (355 male and 361 female subjects). Tenderness with palpation of masseter and temporalis muscles and functional manipulation of lateral and medial pterygoid muscles was registered. The examiners recorded the Angle classification bilaterally for molars, presence of anterior and posterior crossbites, excessive overjet, open and deep bites, functional shift, and severity of anterior crowding. Associations between the occlusal factors and muscle tenderness according to sex were evaluated with chi-square analysis. Statistically significant associations were found between masticatory muscle tenderness and all the investigated occlusal factors except posterior crossbite and functional shift. Masseter, medial, and lateral pterygoid muscle tenderness was higher in female subjects. Medial and lateral pterygoid muscle tenderness in Class I cases and masseter and medial pterygoid muscle tenderness in Class II, division 1 malocclusion cases were higher in female subjects (P < .05). In open-bite cases, medial pterygoid muscle tenderness (P < .05), in deep-bite cases, masseter (P < .01) and medial pterygoid (P < .05) muscle tenderness, and in excessive overjet cases, masseter muscle tenderness (P < .05) were also higher in female subjects. These results suggest that greater masticatory muscle tenderness in female subjects may contribute to the greater prevalence of temporomandibular disorders in them.

The etiology of intra- and extracapsular temporomandibular disorders (TMD) remains a subject of dispute, particularly with regard to the role of occlusion. Some studies on patient and nonpatient populations have found a significant correlation between malocclusions and signs and symptoms of TMD,1–6 whereas others have not been able to substantiate these results.7–10 

Several investigators have reported that the morphology of craniofacial skeletons correlates with forms of jaw muscles.11,12 It has been shown that the chewing pattern is influenced by the presence of certain malocclusions, and that there is a relationship between facial shape and the electrical activity in the chewing muscles.13 For example, activity in the masticatory muscles is generally higher in individuals with a rectangular face and lower in individuals with a large gonial angle, whereas hyperactivity in the middle and posterior temporalis muscle has been found on the affected side in patients with unilateral posterior crossbite.

The prevalence of occlusal factors in relation to TMD is common in the literature for various ethnic groups worldwide. However, only few studies have attempted to survey the occlusal factors in relation to masticatory muscle tenderness.14,15 

According to the Pancherz,16 children with Class II malocclusion exhibit an impaired muscle activity in comparison with children with normal occlusion. This is especially apparent with respect to the masseter muscle. Deep overbite and Class II, division 2 malocclusions are commonly cited factors in TMJ patient populations,17,18 although the belief in their role is not accepted universally.19 Deep bite is commonly said to be a cause of condylar displacement and masticatory muscle pain.20–23 An increase in muscle tenderness has been reported associated with open bite in a study of children and young adults.15 Riolo et al15 indicated that the relative frequency of muscle tenderness for cusp-to-cusp boy subjects was consistently greater than that for the Class I and Class II boy subjects for all ages. It has also been reported that the muscle coordination during functional movements is different in Class III malocclusion.24 

With these considerations in mind, the aims of this study were to

  • Investigate the relationship between occlusal factors (such as Angle classification of molars, anterior and posterior crossbites, excessive overjet, open and deep bites, functional shift, and anterior crowding) and masticatory muscle tenderness among 10- to 19-year-old Turkish subjects.

  • Identify possible sex differences between female and male subjects.

In the present study, 716 individuals (355 male and 361 female subjects) were selected randomly from four different schools in Konya, Turkey. The distribution of age for all participants is shown in Table 1. The following inclusion criteria were used for the selection of the sample: 10 years of age or older; all permanent first molars erupted; and Caucasian.

TABLE 1.

Number of Female Subjects and Male Subjects by Age Group

Number of Female Subjects and Male Subjects by Age Group
Number of Female Subjects and Male Subjects by Age Group

The examiners recorded the Angle classification bilaterally for molars, presence of anterior and posterior crossbites, excessive overjet, open and deep bites, functional shift, and severity of anterior crowding.

Anteroposterior molar relationship groups were established as (1) Class I, (2) Class II, division 1, (3) Class II, division 2, and (4) Class III on both sides. These classifications were mutually exclusive. The cases with the molars in one side being in Class I and on the other side in Class II or Class III relationship were excluded because of the difficulties of classification.

Crossbites were designated as either present or absent. Anterior and posterior crossbites were recorded as a single tooth or multiple teeth. No scissors bite was observed among all subjects. Overjet or the horizontal distance between the facial surface of the upper central incisors and the facial surface of the lower central incisors was recorded using a periodontal probe. Overjets exceeding six mm were recorded as extreme.

Similarly, overbites were established as (1) open bite (negative overbite), (2) deep bite (overbite greater than the lower incisor's crown height), and (3) overbite less than the total overlap of the lower incisor's crown.15 

Functional shifts in the occlusion were recognized by deconditioning the subject's habitual biting pattern, thus making it possible to measure any functional shift of the mandible. In this way, any functional shift caused by an occlusal interference resulting in a reflex alteration in the movement pattern at the occlusal interface was detected. Deconditioning was accomplished using cotton rolls to separate posterior teeth for three minutes before any measurement of a functional shift was attempted. It was judged as a functional shift present or absent.

Crowding was estimated separately for the anterior segment of the maxillary and mandibular arches. Crowding was recorded as 0 = no crowding; 1 = mild (lack of space for less than half of the mesiodistal width of a tooth in a segment); 2 = moderate (lack of space for half or more of the width of one tooth but less than one tooth); and 3 = severe (lack of space for one tooth or more). Crowding was registered as being present if it was three mm and if it was at least one arch.

Symptoms of tenderness of the masticatory system were recorded on the basis of an anamnestic examination and a clinical examination. The tenderness with palpation of masseter and temporalis muscles and functional manipulation of lateral and medial pterygoid muscles was registered. Muscle tenderness of the anterior temporal, posterior temporal, and insertion of the temporal and superficial masseter was determined by palpation on both sides. Tenderness was graded as Score 0, if subject described no tenderness; Score 1, if the subject could feel the difference between the right and left sides or described little tenderness; Score 2, if described the palpation as painful; and Score 3, if pain gave rise to a palpebral reflex or guarding. Functional manipulation was carried out on the lateral and medial pterygoid muscle according to Okeson,25 and the findings were graded in the same way as for the masseter and temporal muscles. During functional manipulation, all the information needed was obtained by having the patient open wide, protrude against resistance, clench the teeth together, and then bite on a separator. If a muscle was a true source of pain, functional manipulation is helpful in identifying this source.

The examinations were carried out by two trained investigators. The interobserver variability between two trained investigators was low, and the examination error seemed negligible.26 Methods and criteria used in this study have been used as standard procedures in many other epidemiologic investigations and have been proved to be valid.26 

All statistical analyses were performed using the SPSS software package (SPSS for Windows 98, version 10.0, SPSS Inc., Chicago, Ill). Differences in prevalence of masticatory muscle tenderness and occlusal factors and associations between masticatory muscle tenderness and occlusal factors were evaluated using the chi-square test (χ2). Comparisons between the sexes were also performed. Values of P < .05 were considered to indicate statistical significance.

The distribution of different occlusal factors in 10- to 19-year-old Turkish subjects is presented in Table 2. None of the subjects had severe masticatory muscle pain (Score 2, 3), whereas most of the scores were 1. The distributions of masticatory muscle tenderness according to the different occlusal factors are shown in Table 3.

TABLE 2.

Prevalence of Different Occlusal Factors Among 10- to 19-y-old Turkish Subjects

Prevalence of Different Occlusal Factors Among 10- to 19-y-old Turkish Subjects
Prevalence of Different Occlusal Factors Among 10- to 19-y-old Turkish Subjects
TABLE 3.

Distribution of Masticatory Muscle Tenderness Among Different Occlusal Factors

Distribution of Masticatory Muscle Tenderness Among Different Occlusal Factors
Distribution of Masticatory Muscle Tenderness Among Different Occlusal Factors

The prevalence of masticatory muscle tenderness (Score 1, mild tenderness) was 56.25% among 10- to 19-year-old Turkish subjects. In general, 59.83% of female and 52.67% of male subjects had tenderness of the masticatory muscles. It appeared that the functional shift in this sample was quite rare (approximately 1% of the cases), therefore it was excluded from the statistical analyses.

There was an association between Angle Class I and lateral pterygoid muscle tenderness and Angle Class III malocclusion and medial pterygoid muscle tenderness (P < .05). Associations were also found between anterior crossbite with medial pterygoid and temporal muscle tenderness (P < .05); anterior crowding with lateral pterygoid and temporal muscle tenderness (P < .05); excessive overjet with masseter and lateral pterygoid muscle tenderness (P < .05); open bite with medial pterygoid muscle tenderness (P < .05); and deep bite with lateral muscle tenderness (P < .05) (Table 4). In general, medial pterygoid (P < .01), lateral pterygoid (P < .05), and masseter muscle tenderness (P < .05) were high in female subjects (Table 5).

TABLE 4.

The Relationship Between Occlusal Factors and Masticatory Muscle Tenderness

The Relationship Between Occlusal Factors and Masticatory Muscle Tenderness
The Relationship Between Occlusal Factors and Masticatory Muscle Tenderness
TABLE 5.

The Relationship Between Sex and Masticatory Muscle Tenderness

The Relationship Between Sex and Masticatory Muscle Tenderness
The Relationship Between Sex and Masticatory Muscle Tenderness

Medial and lateral pterygoid muscle tenderness in Angle Class I cases and masseter and medial pterygoid muscle tenderness in Angle Class II, division 1 malocclusion cases were higher in female subjects (P < .05). In excessive overjet cases, masseter muscle tenderness (P < .05), in open-bite cases, medial pterygoid muscle tenderness (P < .05), and in deep-bite cases, masseter (P < .01) and medial pterygoid (P < .05) muscle tenderness were also higher in female subjects. Complete findings are presented in Table 6.

TABLE 6.

The Relationship Among Occlusal Factors, Gender, and Masticatory Muscle Tenderness

The Relationship Among Occlusal Factors, Gender, and Masticatory Muscle Tenderness
The Relationship Among Occlusal Factors, Gender, and Masticatory Muscle Tenderness

The prevalence of different occlusal factors or masticatory muscle tenderness has been noted in several re-ports.1–10,12,14,15,27,35,37,38 Some of the prevalence studies exhibit methodological limitations and had a lack of specific diagnostic criteria, small or self-selected samples, and lack of developmental age-specific data. A study with standardized examination techniques, well-defined diagnostic criteria, and a large representative sample would help to substantiate the prevalence of disorders in children.

In a study by Bush,27 nearly 300 dental students were examined for muscle tenderness and various occlusal contacts, and he reported only mild masticatory muscle tenderness. In the present study, none of the subjects had severe masticatory muscle pain (Score 2, 3), whereas most of the scores were 1, in accordance with Bush's findings.

Children with Class II malocclusion tended to have more masticatory muscle tenderness.28 In adults, an association has been demonstrated between muscle tenderness and Class II malocclusion.1 No relationship between muscle tenderness and Angle classification was found in one study.25 Another indicated that neither Class II nor cusp-to-cusp molar relationships were statistically associated with muscle tenderness, whereas a significant interaction was found between molar relation, sex, and age and the odds of having muscle tenderness.15 An autopsy study of young adults13 showed that Class III malocclusions were associated with deviation in the normal form of the temporomandibular joint components, and this was associated with masticatory muscle tenderness. Surprisingly, instead of Angle Class II malocclusion, we found an association between Angle Class I and lateral pterygoid muscle tenderness and Angle Class III with medial pterygoid muscle tenderness.

It has been suggested that undue forces are placed on the masticatory muscles as a consequence of an unfavorable incisor relationship.29 Studies have suggested that factors such as increased overjet and overbite and anterior open bite are likely to be predisposing factors rather than initiating factors in the production of masticatory muscle symptoms.29 However, Seligman et al30 found that overjet was not related to symptoms of TMJ sounds or to masticatory muscle tenderness in a young adult nonpatient population. In the present study, statistically significant relationships were found between increased overjet and masseter and lateral pterygoid muscle tenderness. Our results are not in agreement with the findings of Seligman et al.30 In our study, a statistically significant relationship was found between open bite and medial pterygoid muscle tenderness, in agreement with Riolo et al.15 

Pullinger and Seligman31 found no associations between deep bite (overbite of five mm or more) and masticatory muscle tenderness, and our findings are not in agreement.31 We found a statistically significant relationships between deep bite and lateral pterygoid muscle tenderness.

According to Riolo et al,15 the relative frequencies of muscle tenderness were significantly lower among subjects with a functional shift (17%) than in those without (8%). A relationship between a functional shift and masticatory muscle tenderness was also found for both sexes and across all age groups in the same study.15 However, in the current study, no relationship was found between functional shift and masticatory muscle tenderness for both sexes.

Ahlgren and Posselt32 and Shaw13 have described an association between crossbite and occlusal interferences in children. Shaw13 reported that hyperactivity in the middle and posterior temporalis muscle was found on the affected side in patients with unilateral posterior crossbite. Egermark-Eriksson et al28 indicated that children with crossbite were found to have muscle tenderness more often than children without crossbite, and there does not seem to be any difference in risk between unilateral and bilateral crossbite or between crossbite in premolar and molar segments.33 Results of Egermark-Eriksson and Ingervall33 agree with findings in adults by Mohlin et al.19 However, no relationship was found between posterior crossbite and masticatory muscle tenderness in the present study. We found a statistically significant relationship between anterior crossbite and medial pterygoid and temporal muscle tenderness.

Rantanen34 found 24% of 2218 undergraduate students to have some type of TMD, or other disturbances of mandibular movements, with symptoms more common in girls (30%) than in boys (18%). Currently, it is widely understood that TMD is multifactorial in nature and is more prevalent in girls than in boys.3,35–38 Studies on the development of pain and tenderness in muscles or jaws also revealed higher frequencies in girls than in boys.38–40 Therefore, with respect to masticatory muscle tenderness, it is of a great importance to examine the sex differences in muscle tolerance in relation to the occlusal factors.

In general, our findings indicated that medial pterygoid muscle tenderness, lateral pterygoid muscle tenderness, and masseter muscle tenderness were higher in female than in male subjects. These results are in agreement with the previous epidemiologic studies' results.3,36–38 According to Riolo et al,15 the relative frequencies of muscle tenderness for cusp-to-cusp boy subjects were consistently greater than those for the Class I and Class II boy subjects for all ages. The girl molar classification groups showed no systematic relationship across age. In the present study, medial pterygoid muscle tenderness was higher in female subjects for both Angle Class I and Class II, division 1, and with open bite. Medial pterygoid muscle tenderness was found in subjects with excessive overjet, and masseter muscle tenderness was found in a higher ratio in female subjects. Masseter and medial pterygoid muscle tenderness was also higher in female subjects with deep bite. The highest prevalence of female subjects classified with some degree of muscle tenderness associated with different occlusal characteristics may be related to typical physiologic differences of the feminine sex, such as regular hormonal variations, muscular structure, and different characteristics of the conjunctive tissue. These matters need to be investigated fully.

The prevalence of masticatory muscle tenderness (Score 1, mild tenderness) was found in more than 50% of 10- to 19-year-old Turkish subjects. This percentage seemed to increase with age and become higher in the adult population.

Statistically significant relationships were found between masticatory muscle tenderness and all investigated occlusal factors except posterior crossbite and functional shift. It appears that short-term reversible therapy is adequate to resolve most muscle problems in most children. Certainly, studies are needed to confirm these findings. Studies that evaluate the effectiveness of treatments need to be controlled for each specific diagnosis (ie, masticatory muscle disorders vs disc interference disorders).

Statistically significant sex differences were found between different occlusal factors and masticatory muscle tenderness. Medial and lateral pterygoid muscle tenderness in Angle Class I cases and masseter and medial pterygoid muscle tenderness in Angle Class II, division 1 malocclusion cases were higher in female subjects. In excessive overjet cases, masseter muscle tenderness (P < .05), in open-bite cases, medial pterygoid muscle tenderness (P < .05), and in deep-bite cases, masseter (P < .01) and medial pterygoid (P < .05) muscle tenderness were also higher in female subjects. These results suggest that greater masticatory muscle tenderness in female subjects may contribute to the greater prevalence of TMD in them.

At this time, there is no scientific documentation that early correction of malocclusion will prevent masticatory muscle or temporomandibular joint disorders. Well-controlled longitudinal studies are needed in this area.

1
Demir
,
A.
,
T.
Uysal
,
E.
Guray
, and
F.
Basciftci
.
The relationship between bruxism and occlusal factors among seven- to 19-year old Turkish children.
Angle Orthod. 2004;74. In press
.
2
Nilner
,
M.
Relationship between oral parafunctions and functional disturbances in the stomatognathic system in 15 to 18 year olds.
Acta Odontol Scand
1983
.
41
:
197
201
.
3
Wanman
,
A.
The relationship between muscle tenderness and craniomandibular disorders: a study of 35 year olds from the general population.
J Orofac Pain
1995
.
9
:
235
243
.
4
Heikinheimo
,
K.
,
K.
Salmi
,
S.
Myllamiemi
, and
P.
Kirveskari
.
A longitudinal study of occlusal interferences and signs of craniomandibular disorder at the ages of 12 and 15 years.
Eur J Orthod
1990
.
12
:
190
197
.
5
Olsson
,
M.
and
B.
Lindqvist
.
Mandibular function before and after orthodontic treatment.
Eur J Orthod
1995
.
17
:
205
214
.
6
Egermark
,
I.
and
A.
Ronnerman
.
Temporomandibular disorders in the active phase of orthodontic treatment.
J Oral Rehabil
1995
.
3
:
613
618
.
7
De Boever
,
J. A.
and
L.
van den Berghe
.
Longitudinal study of functional conditions in the masticatory system in Flemish children.
Community Dent Oral Epidemiol
1987
.
15
:
100
103
.
8
Vanderas
,
A. P.
The relationship between craniomandibular dysfunction and malocclusion in white children with unilateral cleft lip and cleft lip and palate.
Cranio
1989
.
7
:
200
204
.
9
Seligman
,
D. A.
and
A. G.
Pullinger
.
The role of intercuspal occlusal relationships in temporomandibular disorders.
J Craniomand Disord Facial Oral Pain
1991
.
5
:
96
106
.
10
Barone
,
A.
,
L.
Sbordone
, and
L.
Ramaglia
.
Craniomandibular disorders and orthodontic treatment need in children.
J Oral Rehabil
1997
.
24
:
2
7
.
11
Van Spronsen
,
P. H.
,
W. A.
Weijs
,
J.
Valk
,
B.
Prahl-Andersen
, and
F. C.
Van Ginkel
.
Comparison of jaw-muscle bite-force cross-sections obtained by means of magnetic resonance imaging and high resolution CT scanning.
J Dent Res
1989
.
68
:
1765
1770
.
12
Welis
,
W. A.
and
B.
Hillen
.
Correlations between the cross sectional area of the jaw muscles and craniofacial sizes and shapes.
Am J Phys Anthropol
1986
.
70
:
423
428
.
13
Shaw
,
W. C.
Orthodontics and Occlusal Management. Chapter 17.
Wright; 1993:262–263
.
14
Sari
,
S.
and
H.
Sonmez
.
The relationship between occlusal factors and bruxism in permanent and mixed dentition in Turkish children.
J Clin Pediatr Dent
2001
.
25
:
191
194
.
15
Riolo
,
M. L.
,
D.
Brandt
, and
T. R.
TenHave
.
Associations between occlusal characteristics and signs and symptoms of TMJ dysfunction in children and young adults.
Am J Orthod Dentofacial Orthop
1987
.
92
:
467
477
.
16
Pancherz
,
H.
The Herbst appliance—its biologic effects and clinical use.
Am J Orthod
1985
.
87
:
1
20
.
17
Demir
,
A.
and
E.
Güray
.
The prevalence of temporomandibular dysfunction in 6–19 year old Turkish children.
Eur J Orthod
2002
.
24
:
549
.
18
Solberg
,
W. K.
and
D. A.
Seligman
.
Temporomandibular orthopedics: A new vista in orthodontics.
In: Johnston LA Jr, ed. New Vistas in Orthodontics. Philadelphia, Penn: Lea & Febiger; 1985:148–183
.
19
Mohlin
,
B.
and
S.
Kopp
.
A clinical study on the relationship between malocclusions, occlusal interferences and mandibular pain and dysfunction.
Swed Dent J
1978
.
2
:
105
112
.
20
Berry
,
D. C.
and
A. C.
Watkinson
.
Mandibular dysfunction and incisor relationship: a theoretical explanation for the clicking joint.
Br Dent J
1978
.
144
:
74
77
.
21
Bell
,
W. E.
Clinical Management of Temporomandibular Disorders.
Chicago, Ill: Year Book Medical; 1982:71–74
.
22
Heloe
,
B.
,
A. N.
Heiberg
, and
B. S.
Krogstad
.
A multiprofessional study of patients with myofascial pain dysfunction syndrome.
Acta Odontol Scand
1980
.
38
:
1
9
.
23
Lieberman
,
M.
,
E.
Gazit
,
C.
Fuchs
, and
P.
Lilos
.
Mandibular dysfunction in 10–18 year old school children as related to morphological occlusion.
J Oral Rehabil
1985
.
12
:
209
214
.
24
Ahlgren
,
J.
Form and function of Angle Class III malocclusion: a cephalometric and electromyographic study.
Trans Eur Orthod Soc
1970
.
46
:
77
88
.
25
Okeson
,
J. P.
Management of Temporomandibular Disorders and Occlusion. 4th ed.
Mosby Year Book Inc; 1998: St. Louis, Missouri, USA; 248–259
.
26
Carlsson
,
G. E.
,
I.
Egermark-Eriksson
, and
T.
Magnusson
.
Intra- and interobserver variation in functional examination of the masticatory system.
Swed Dent J
1980
.
4
:
187
194
.
27
Bush
,
F. M.
Malocclusion, masticatory muscle, and temporomandibular joint tenderness.
J Dent Res
1985
.
64
:
129
133
.
28
Egermark-Eriksson
,
I.
,
B.
Ingervall
, and
G. E.
Carlsson
.
The dependence of mandibular dysfunction in children on functional and morphologic malocclusion.
Am J Orthod
1983
.
83
:
187
194
.
29
Jagger
,
R. G.
,
J. F.
Bates
, and
S.
Kopp
.
Temporomandibular Joint Dysfunction. 1st ed.
Wright; 1994: Cambridge, UK; 23–29
.
30
Seligman
,
D. A.
,
A. G.
Pullinger
, and
W. K.
Solberg
.
Temporomandibular disorders. Part III. Occlusal and articular factors associated with muscle tenderness.
J Prosthet Dent
1988
.
59
:
483
489
.
31
Pullinger
,
A. G.
and
D. A.
Seligman
.
Overbite and overjet characteristics of refined diagnostic groups of temporomandibular disorder patients.
Am J Orthod Dentofacial Orthop
1991
.
100
:
401
415
.
32
Ahlgren
,
J.
and
U.
Posselt
.
Need of functional analysis and selective grinding in orthodontics: a clinical and electromyographic study.
Acta Odontol Scand
1968
.
21
:
187
217
.
33
Egermark-Eriksson
,
I.
and
B.
Ingervall
.
Occlusal anomalies predisposing to occlusal interference in children.
Angle Orthod
1982
.
52
:
293
299
.
34
Rantanen
,
A. V.
Leukanivelen fysiologisen subluksaation yleisyydesta nuorille. Kliinisia havaintoja.
Suom Hammaslaa Karilehti
1954
.
50
:
133
137
.
35
Agerberg
,
G.
and
I.
Inkapööl
.
Craniomandibular disorders in an urban Swedish population.
J Craniomand Disord Facial Oral Pain
1990
.
4
:
154
164
.
36
Dworkin
,
S. F.
,
K. H.
Huggins
, and
L.
LeResche
.
et al
.
Epidemiology of signs and symptoms in temporomandibular disorders: clinical signs in cases and controls.
J Am Dent Assoc
1990
.
120
:
273
281
.
37
Krogstad
,
B. S.
,
B. L.
Dahl
,
T.
Eckersberg
, and
B.
Ogaard
.
Sex differences in signs and symptoms from masticatory and other muscles in 19-year old individuals.
J Oral Rehabil
1992
.
19
:
435
440
.
38
Jensen
,
R.
,
B. K.
Rasmussen
,
B.
Pedersen
,
I.
Lous
, and
J.
Olesen
.
Cephalic muscle tenderness and pressure pain threshold in a general population.
Pain
1992
.
48
:
197
203
.
39
Visser
,
S. L.
and
W.
De Rlike
.
Influence of sex and age on EMG contraction pattern.
Eur. Neurol
1974
.
12
:
229
235
.
40
Plesh
,
O.
,
D. A.
Curtis
,
L. J.
Hall
, and
A.
Miller
.
Gender difference in jaw pain induced by clenching.
J Oral Rehabil
1998
.
25
:
258
263
.

Author notes

Corresponding author: Dr. Abdullah Demir, Selcuk Universitesi, Dishekimligi Fak. Ortodonti Anabilim Dali, 42079, Kampüs, Konya, Turkey (abd_demir@hotmail.com)