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Temporomandibular joint intermittent closed lock: clinic and magnetic resonance imaging findings
Vol. 118 No. 4 October 2014
Temporomandibular joint intermittent closed lock: clinic and magnetic resonance imaging findings Namiaki Takahara, DDS,a Hideki Imai, DDS, PhD,b Satoshi Nakagawa, DDS,a Kanako Sumikura, DDS,a Fumihiko Tsushima, DDS, PhD,c and Ken Omura, DDS, PhDd Tokyo Medical and Dental University and Hitachi, Ltd; Hitachinaka General Hospital; Tokyo and Hitachinaka, Japan
Objective. This study was carried out to describe the clinical and magnetic resonance imaging (MRI) findings of patients with intermittent closed lock (ICL) of the temporomandibular joint (TMJ). Study design. This retrospective study included 58 joints with ICL and 526 joints without ICL as controls. We compared the MRI findings between the patients with and without ICL and investigated clinical and MRI finding of ICLpatients. We divided ICL patients into 2 groups based on the treatment efficacy: effective and ineffective. Results. There were significant differences in the prevalence of disk deformity between the joints with and without ICL. Masticatory muscle pain was observed in 41.7% of the effective group and in 80% of the ineffective group, respectively. Conclusions. These results suggest that there is a relationship among the onset of ICL and disk deformation. Masticatory musclepain was significantly observed in the ineffective group. (Oral Surg Oral Med Oral Pathol Oral Radiol 2014;118: 418-423)
Intermittent closed lock usually manifests with clicking because of anterior disk displacement with reduction, and sometimes with limited mouth opening as a result of disk displacement without reduction. It corresponds to the early/intermediate stage of internal derangement of the temporomandibular joint (TMJ) according to Wilkes’ staging criteria.1 Clicking alone does not interfere with activities of daily living; for this reason, some clinicians are of the opinion that no treatment is necessary.2 However, interference with activities of daily living does occur with intermittent closed lock.3 The clinical picture is varied and is not yet fully described. However, in terms of diagnosis and therapy, only a few studies have been concerned with the occurrence of intermittent closed lock in relation to the magnetic resonance imaging (MRI) findings of disk displacement and morphology. Therefore, the aims of this retrospective study were(1) to describe the clinical characteristics and MRI findings of patients with intermittent closed lock and (2) to verify the efficacy of treatments for intermittent closed lock. a Clinical Fellow, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. b Chief, Department of Dentistry and Oral Surgery, Hitachi, Ltd., Hitachinaka General Hospital, Hitachinaka, Japan. c Associate Professor, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. d Professor, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Received for publication Mar 6, 2014; returned for revision May 12, 2014; accepted for publication May 18, 2014. Ó 2014 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2014.05.019
418
MATERIALS AND METHODS Patients The patients were 58 consecutive patients with unilateral intermittent closed lock among 1898 temporomandibular disorder (TMD) patients who had been examined between January 2005 and December 2011 in the Department of Oral and Maxillofacial Surgery of Tokyo Medical and Dental University. All patients included in the study were clinically investigated according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I protocol.4 There were 47 female participants and 11 male participants ages 13 to 64 years (mean 27.5 years; Table I). The clinical diagnostic criteria for intermittent closed lock were as follows5: 1. The occurrence of times when it was possible to open the mouth widely and times when mouth opening was limited; 2. Spontaneous resolution of the mouth-opening limitation or resolution in response to force exerted by the patient; 3. Absence of pain associated with the mouth-opening limitation or with resolution of the mouth-opening limitation; 4. Occurrence of the mouth-opening limitation just described at least once a month.
Statement of Clinical Relevance The aim of this study is to describe the clinical characteristics and magnetic resonance imaging (MRI) findings of patients with intermittent closed lock and to verify the efficacy of treatments for intermittent closed lock.
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Table I. Patient demographic characteristics Variable
Patients with ICL
Patients without ICL
Number of patients Male Female Age (mean SD; years)
58 11 47 27.5 11.9
461 128 333 29.7 14.0
ICL, intermittent closed lock; SD, standard deviation.
The patients with pain were excluded for following reasons: (1) Joint pain associated with the mouthopening limitation indicates closed lock, and (2) joint pain associated with resolution of the mouth-opening limitation indicates anterior disk displacement with reduction of pain. In the control group, there were 526 joints of 461 patients with anterior disk displacement without intermittent closed lock. The controls had consulted our department during the same period as the study group had consulted us. The control group consisted of 333 femaleparticipants and 128 male participants ages 13 to 80 years (mean 29.7 years). MRI MR images were obtained by using a 1.5 Tesla unit (Magnetom Vision; Siemens, Erlangen, Germany) with a 3-inch-diameter bilateral 2 TMJ surface coil. In the closed-mouth position, proton density weighted images were obtained in both the sagittal plane (TR/TE, 1000/ 20 ms) and the coronal plane (TR/TE, 960/15 ms). In the open-mouth position, proton density weighted images were obtained in the sagittal plane (TR/TE, 1850/15 ms). All images were obtained with a 3 mm section thickness, a field of view (FOV) of 90 120 mm, a matrix of 154 256 pixels, and 1 to 2 excitations. MR images were evaluated for the presence or absence of disk displacement and disk morphology. Normal disk position in the sagittal plane was defined as the posterior band of the disk being at the 12 o’clock position relative to the condyle, whereas anterior disk displacement was defined as the posterior band of the disk being in an anterior position relative to the superior part of the condyle. The degree of anterior disk displacement was categorized as slight, moderate, or severe and was defined according to the findings of the closed-mouth images. Slight displacement occurs when the posterior band of the disk is located in the articular surface of the condyle. Moderate displacement occurs when the posterior band of the disk is located in the posterior surface of the eminence yet is not contacting the articular surface of the condyle. Severe displacement occurs when the posterior band of the disk is located at the bottom of the articular eminence. Sideways displacement was defined as the disk crossing
over one of the lines through the condylar poles in the medial and lateral direction6 (Figure 1). Disk morphology was also evaluated in the closedmouth position. The biconcave type was defined as normal, whereas the other types (biconvex, enlargement of posterior band, even thickness, and reversed) were all considered to be deformities7 (Figure 2). Treatments The treatment for intermittent closed lock consisted of the disk repositioning exercise8 combined with the anterior repositioning splint.9 Arthrocentesis10 was performed if needed. The disk repositioning exercise protocol was as follows: (1) opening the mouth maximally with the opening click; (2) closing the mouth along the protrusive border movement path; (3) contacting the teeth in the protruded position; (4) retruding to a contact position just before the click; and (5) opening the mouth maximally again without the opening click. This exercise was repeated for 5 minutes before each meal, and the patient must maintain the disk repositioning mandibular position all day if possible. Repositioning splints were used to keep the disk repositioning mandible position during sleeping. Arthrocentesis was performed for patients who did not experience improvement and for cases wherein troubles in daily life were predicted to shorten the treatment period greatly. Patients who experienced the complete cessation of locking and absence of clicking during palpation were defined as in the effective group, and patients who had no change in the frequency of locking or progressed to permanent lock were defined as in the ineffective group. In addition, the longevity of the curative effect was judged 3 months after each medical treatment began. Data analysis The clinical data, the treatment method, and the clinical outcome were collected retrospectively from the patients’ records. The clinical parameters included pain on clicking and masticatory pain. We compared the MRI findings between the patients with and without intermittent closed lock by using Fisher’s exact test and Pearson’s chi-square test. The clinical and MRI findings of the effective group were compared with those of the ineffective group. A comparison examination of both groups was statistically carried out at the time of the initial visit by using Fisher’s exact test. Statistical analysis was performed using SPSS 18.0 (SPSS, Chicago, IL). A Pvalue of .05 was considered statistically significant.
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Fig. 1. The degree of anterior disk displacement. 1, Slight. 2, Moderate.3, Severe.
RESULTS In TMJs with intermittent closed lock, 23 of the 58 joints (39.7%) were characterized by slight anterior disk displacement, 31 joints (53.4%) were moderate, and 4 joints (6.9%) were severe. In TMJs without intermittent closed lock, 308 of the 526 joints (58.6%) were characterized by slight anterior disk displacement, 209 joints (39.7%) were moderate, and 9 joints (1.7%) were severe. The difference in the degree of anterior displacement between the groups was not statistically significant. In TMJs with intermittent closed lock, 34 of the 58 joints (58.6%) had typical anterior disk displacement, and 24 of the 58 joints (41.4%) had rotational anterior displacement with an associated sideways shift. In TMJs without intermittent closed lock, 308 of the 526 joints (58.6%) had typical anterior disk displacement, and 215 of the 526 joints (41.4%) had rotational anterior displacement with an associated sideways shift. There was no significant difference in the frequency of occurrence of sideways displacement between the groups. In TMJs with intermittent closed lock, 26 of the 58 joints (44.8%) exhibited disk deformity, compared with 118 of the 526 joints (22.4%) in TMJs without intermittent closed lock. The prevalence of disk deformity
between the 2 groups was significantly different (P < .001) (Table II). The patients who improved through the disk repositioning exercises alone included 4 joints. Thirty-seven cases improved through a combination of disk repositioning exercises and a repositioning splint. No improvements were observed in 2 joints that had undergone arthrocentesis. The total efficacy rate for intermittent lock was 82.8% (Table III). While comparing the clinical and MRI findings of the effective group and ineffective group, masticatory muscle pain was observed in 20 of the 48 TMJs (41.7%) in the effective group and in 8 of the 10 TMJs (80.0%) in the ineffective group. Therefore, the masticatory muscle pain was significantly more common in the ineffective group than in the effective group (P ¼ .03). In contrast, there was no significant difference in displacement or deformation of the disk between the groups (Table IV).
DISCUSSION This retrospective study of temporomandibular joint intermittent closed lock revealed a possible relationship among the onset of intermittent closed lock, disk deformation, and degree of anterior placement. When intermittent closed lock patients were divided into
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Fig. 2. Disk deformity.1, Enlargement of posterior band. 2, Folding. 3, Biplanner. 4, Biconvex.
2groups based on the efficacy of treatment, masticatory muscle pain was significantly more common in the ineffective group than in the effective group. Although intermittent closed lock generally involves a reduction in disk displacement, temporary trismus without reduction may be presented too. Intermittent closed lock is a relatively rare pathologic condition with a variety of clinical features; consequently, there are many unclear points regarding its etiology. In joints with no disk displacement, articular disk deformation is rarely seen; however, based on the pathologic progression of internal derangement, various differences may be found, such as disk deformation, degree of displacement, and orientation. Westesson et al.7 and de Leeuw et al.11 reported on the relationship between the degree of displacement and disk deformation in disk displacement found in the temporomandibular joint. Westesson et al.7 classified articular disk formation into 5 categories: biconcave, reversed, enlargement of posterior band, biplanar, and biconvex. As a result of examining the relationship with the pathology of
internal derangement, they found articular disk deformation in 64 out of 77 joints with anterior displacement without reduction. Furthermore, in patients diagnosed with internal derangement, Almas¸an et al.12 classified 74 joints into 3 groups: normal disk position (31 joints), anterior disk displacement with reduction (27 joints), and anterior disk displacement without reduction (16 joints). After assessing the disk formation in each group, they reported that disk deformation afflicted 16 joints (51.7%) in the normal disk position group, 26 joints (96.3%) in the anterior disk displacement with reduction group, and all joints with anterior disk displacement without reduction. On the basis of these findings, it is believed that disk deformation tends to develop as the degree of anterior disk displacement progresses and that it occurs at a high rate. Reports indicate that lateral disk placement is significantly higher in intermittent closed lock cases than in cases of anterior disk displacement with reduction and without intermittent closed lock13; further reports claim that anterior disk displacement contributes to intermittent
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Table II. MRI findings of the joints with and without intermittent closed lock Variable Degree of anterior disk displacement Slight Moderate Severe Sideways displacement Disk deformity
Joints with ICL (N ¼ 58)
23 31 4 24 26
Joints without ICL (N ¼ 526)
(39.7%) (53.4%) (6.9%) (41.4%) (44.8%)
308 209 9 215 118
(58.6%) (39.7%) (1.7%) (40.9%) (22.4%)
P value
.002*
.524 < .001y
ICL, intermittent closed lock; MRI, magnetic resonance imaging. *Pearson’s chi-square test. y Fisher’s exact test.
Table III. Therapeutic effect of the patients with intermittent closed lock Treatment method DR exercise DR exercise þARS therapy DR exercise þARS therapy þArthrocentesis Total
Effective
Ineffective
4
0
37
8
7
2
48 (82.8%)
10 (17.2%)
ARS, anterior repositioning splint therapy; DR, disk repositioning.
Table IV. Clinical and MRI findings of the effective group and the ineffective group with intermittent closed lock Effective group Ineffective group (N ¼ 48) (N ¼ 10) P Value Pain at clicking Masticatory pain Degree of anterior disk displacement Slight Moderate Severe Sideways displacement Disk deformity
20 (41.7%) 20 (41.7%)
3 (30%) 8 (80%)
.377 .03*
18 27 3 21 23
5 4 1 3 3
.636
(37.5%) (56.3%) (6.2%) (43.8%) (39.6%)
(50%) (40%) (10%) (30%) (30%)
.331 .248
MRI, magnetic resonance imaging. *Fisher’s exact test.
closed lock more than disk deformation contributes to it.14 In the present study, we found disk deformation in 44.8% of the joints in the group with intermittent closed lock and in 22.4% in the group without intermittent closed lock. We also found that disk deformation was significantly higher in the group with intermittent closed lock. Furthermore, we found that the anterior placement of the disk tended to be advanced in the group with intermittent closed lock. This suggests that there is a relationship among the onset of intermittent closed lock, disk deformation, and degree of anterior placement.
The disk and condylar translation pathway have a complex impact on intermittent closed lock and may lead to situations where reduction is not possible. Becauseintermittent closed lock is the intermediate pathologic condition of the click and closed lock, the onset of closed lock should be prevented while aiming to improve the pain and discomfort of the click. Disk repositioning exercises8 and splint therapy are considered effective for the click. These therapies aim to reposition and adapt the displaced disk and are believed to be useful in the prevention of closed lock. Treatments offered byour department for intermittent closed lock include the disk repositioning exercise,8 anterior repositioning splint,9 and arthrocentesis.10 We generally opt for disk repositioning exercises, which work well in conjunction with anterior repositioning splint therapy. We perform arthrocentesis for patients who do not improve with the combined therapy or for patients who wish to reduce the duration of the treatment, because treatment does cause a major disturbance to daily life activities. Yoda et al.5 conducted a multifacility survey on the clinical features and outcomes of intermittent closed lock by examining the therapeutic outcomes of disk repositioning exercise alone and the combined therapy of disk repositioning exercises with anterior repositioning splint. They reported that the symptom disappeared in 41.7% of the participants who underwent diskrepositioning exercises alone and in 60% of the participants who underwent diskrepositioning exercises with the anterior repositioning splint. For the present study, only 4 of the patients we reviewed underwent disk repositioning exercises alone; most patients chose to receive an anterior repositioning splint with the disk repositioning exercises, and the response rate of this combined therapy was 75.5%. Therefore, we believe that disk repositioning exercises with the anterior repositioning splint is a valid primary treatment for intermittent closed lock. Moreover, arthrocentesis was additionally performed for 9 cases because the combination of disk repositioning exercises and repositioning splint was ineffective in these cases. An improvement was observed in 7 of these 9 cases (77.8%). Regarding the effects of arthrocentesis, Nitzan et al.10 described the reduced viscosity of synovial fluid and the removal of the vacuum effect between the disk and the mandible fossa, which improves the translation motility of the disk and is believed to improve the symptoms of intermittent closed lock. Therefore, arthrocentesis is indicated for intermittent closed lock when disk repositioning exercises and repositioning splints have been ineffective. As we compared the clinical and MRI findings of the effective group and ineffective group, we noticed that masticatory muscle pain was significantly more common in the ineffective group than in the effective group.
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However, no significant difference was observed in the placement or deformation of the disk between the both groups. Therefore, not only should the muscle be treated directly in intermittent closed lock, but the muscle tension should also be eased. REFERENCES 1. Wilkes CH. Internal derangements of temporomandibularjoint pathologic variations. Arch Otolaryngol Head Necksurg. 1989;115:469-477. 2. Okeson JP. Long-term treatment of disk-interference disordersof the temporomandibular joint with anterior repositioningocclusal splints. J Prosthet Dent. 1988;60:611-616. 3. Friedman MH. Closed lock. A survey of 400 cases. Oralsurg Oral Medoral Pathol Oral Radiol Endod. 1993;75:422-427. 4. Dworkin SF, LeResche L. Research diagnostic criteria fortemporomandibular disorders: Review, criteria, examinations andspecifications, critique. J Craniomandib Disord. 1992;6: 301-355. 5. Yoda T, Sakamoto I, Imai H, et al. Response of temporomandibular joint intermittent closed lock to different treatment modalities:a multicenter survey. Cranio. 2006;24:130-136. 6. Tasaki MM, Westesson PL. Temporomandibular joint: diagnostic accuracy with sagittal and coronal MR imaging. Radiology. 1993;186:723-729. 7. Westesson PL, Bronstein SL, Liedberg J. Internal derangement of the temporomandibular joint:morphologic description withcorrelation to joint function. Oral Surg Oral Med Oral Pathol. 1985;59:323-331. 8. Yoda T, Sakamoto I, Imai H, et al. A randomized controlled trial of therapeuticexercise for clicking due to disk anteriordisplacement with reduction in the temporomandibular joint. Cranio. 2003;21:10-16.
ORIGINAL ARTICLE Takahara et al. 423 9. Kurita H, Kurashina K, Baba H, Ohtsuka A, Kotani A, Kopp S. Evaluation of disk capture with a splint repositioning appliance: clinical and critical assessment with MR imaging. Oral Surg Oralmed Oral Pathol Oral Radiol Endod. 1998;85:377-380. 10. Nitzan DW, Dolwick MF, Martinez GA. Temporomandibular joint arthrocentesis: a simplified treatment for severe, limited mouth opening. J Oral Maxillofac Surg. 1991;49:1163-1167. 11. de Leeuw R, Boering G, Stegenga B, de Bont LG. TMJ articular disc position and configuration 30 y after initial diagnosis of internal derangement. J Oral Maxillofac Surg. 1995;53:234-242. 12. Almas¸an OC, Hedes¸iu M, Baciut¸ G, Leucut¸a DC, Baciut¸ M. Disk and jointmorphologyvariations on coronal and sagittal MRI in temporomandibular joint disorders. Clin Oral Investig. 2013;17: 1243-1250. 13. Aomura T, Matsuo T, Adachi A, Mizuki H. Association between the direction of disc displacement and intermittent lock in the temporomandibular joint. J Jpn Soc TMJ. 2004;16:141-145. 14. Ide T, Nagai I, Miyazaki A, Yamaguchi A, Kohama G. Clinical study of intermittent lock of the temporomandibular joint:relation to frequency of intermittent lock on clinical examination and magnetic resonance imaging. Jpn J Oral Maxillofac Surg. 2002;48:191-194.
Reprint requests: Namiaki Takahara, DDS Department of Oral and Maxillofacial Surgery Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University 1-5-45, Yushima, Bunkyo-ku Tokyo 113-8549 Japan [email protected]
Temporomandibular joint intermittent closed lock: clinic and magnetic resonance imaging findings Namiaki Takahara, DDS,a Hideki Imai, DDS, PhD,b Satoshi Nakagawa, DDS,a Kanako Sumikura, DDS,a Fumihiko Tsushima, DDS, PhD,c and Ken Omura, DDS, PhDd Tokyo Medical and Dental University and Hitachi, Ltd; Hitachinaka General Hospital; Tokyo and Hitachinaka, Japan
Objective. This study was carried out to describe the clinical and magnetic resonance imaging (MRI) findings of patients with intermittent closed lock (ICL) of the temporomandibular joint (TMJ). Study design. This retrospective study included 58 joints with ICL and 526 joints without ICL as controls. We compared the MRI findings between the patients with and without ICL and investigated clinical and MRI finding of ICLpatients. We divided ICL patients into 2 groups based on the treatment efficacy: effective and ineffective. Results. There were significant differences in the prevalence of disk deformity between the joints with and without ICL. Masticatory muscle pain was observed in 41.7% of the effective group and in 80% of the ineffective group, respectively. Conclusions. These results suggest that there is a relationship among the onset of ICL and disk deformation. Masticatory musclepain was significantly observed in the ineffective group. (Oral Surg Oral Med Oral Pathol Oral Radiol 2014;118: 418-423)
Intermittent closed lock usually manifests with clicking because of anterior disk displacement with reduction, and sometimes with limited mouth opening as a result of disk displacement without reduction. It corresponds to the early/intermediate stage of internal derangement of the temporomandibular joint (TMJ) according to Wilkes’ staging criteria.1 Clicking alone does not interfere with activities of daily living; for this reason, some clinicians are of the opinion that no treatment is necessary.2 However, interference with activities of daily living does occur with intermittent closed lock.3 The clinical picture is varied and is not yet fully described. However, in terms of diagnosis and therapy, only a few studies have been concerned with the occurrence of intermittent closed lock in relation to the magnetic resonance imaging (MRI) findings of disk displacement and morphology. Therefore, the aims of this retrospective study were(1) to describe the clinical characteristics and MRI findings of patients with intermittent closed lock and (2) to verify the efficacy of treatments for intermittent closed lock. a Clinical Fellow, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. b Chief, Department of Dentistry and Oral Surgery, Hitachi, Ltd., Hitachinaka General Hospital, Hitachinaka, Japan. c Associate Professor, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. d Professor, Department of Oral and Maxillofacial Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Received for publication Mar 6, 2014; returned for revision May 12, 2014; accepted for publication May 18, 2014. Ó 2014 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2014.05.019
418
MATERIALS AND METHODS Patients The patients were 58 consecutive patients with unilateral intermittent closed lock among 1898 temporomandibular disorder (TMD) patients who had been examined between January 2005 and December 2011 in the Department of Oral and Maxillofacial Surgery of Tokyo Medical and Dental University. All patients included in the study were clinically investigated according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I protocol.4 There were 47 female participants and 11 male participants ages 13 to 64 years (mean 27.5 years; Table I). The clinical diagnostic criteria for intermittent closed lock were as follows5: 1. The occurrence of times when it was possible to open the mouth widely and times when mouth opening was limited; 2. Spontaneous resolution of the mouth-opening limitation or resolution in response to force exerted by the patient; 3. Absence of pain associated with the mouth-opening limitation or with resolution of the mouth-opening limitation; 4. Occurrence of the mouth-opening limitation just described at least once a month.
Statement of Clinical Relevance The aim of this study is to describe the clinical characteristics and magnetic resonance imaging (MRI) findings of patients with intermittent closed lock and to verify the efficacy of treatments for intermittent closed lock.
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Table I. Patient demographic characteristics Variable
Patients with ICL
Patients without ICL
Number of patients Male Female Age (mean SD; years)
58 11 47 27.5 11.9
461 128 333 29.7 14.0
ICL, intermittent closed lock; SD, standard deviation.
The patients with pain were excluded for following reasons: (1) Joint pain associated with the mouthopening limitation indicates closed lock, and (2) joint pain associated with resolution of the mouth-opening limitation indicates anterior disk displacement with reduction of pain. In the control group, there were 526 joints of 461 patients with anterior disk displacement without intermittent closed lock. The controls had consulted our department during the same period as the study group had consulted us. The control group consisted of 333 femaleparticipants and 128 male participants ages 13 to 80 years (mean 29.7 years). MRI MR images were obtained by using a 1.5 Tesla unit (Magnetom Vision; Siemens, Erlangen, Germany) with a 3-inch-diameter bilateral 2 TMJ surface coil. In the closed-mouth position, proton density weighted images were obtained in both the sagittal plane (TR/TE, 1000/ 20 ms) and the coronal plane (TR/TE, 960/15 ms). In the open-mouth position, proton density weighted images were obtained in the sagittal plane (TR/TE, 1850/15 ms). All images were obtained with a 3 mm section thickness, a field of view (FOV) of 90 120 mm, a matrix of 154 256 pixels, and 1 to 2 excitations. MR images were evaluated for the presence or absence of disk displacement and disk morphology. Normal disk position in the sagittal plane was defined as the posterior band of the disk being at the 12 o’clock position relative to the condyle, whereas anterior disk displacement was defined as the posterior band of the disk being in an anterior position relative to the superior part of the condyle. The degree of anterior disk displacement was categorized as slight, moderate, or severe and was defined according to the findings of the closed-mouth images. Slight displacement occurs when the posterior band of the disk is located in the articular surface of the condyle. Moderate displacement occurs when the posterior band of the disk is located in the posterior surface of the eminence yet is not contacting the articular surface of the condyle. Severe displacement occurs when the posterior band of the disk is located at the bottom of the articular eminence. Sideways displacement was defined as the disk crossing
over one of the lines through the condylar poles in the medial and lateral direction6 (Figure 1). Disk morphology was also evaluated in the closedmouth position. The biconcave type was defined as normal, whereas the other types (biconvex, enlargement of posterior band, even thickness, and reversed) were all considered to be deformities7 (Figure 2). Treatments The treatment for intermittent closed lock consisted of the disk repositioning exercise8 combined with the anterior repositioning splint.9 Arthrocentesis10 was performed if needed. The disk repositioning exercise protocol was as follows: (1) opening the mouth maximally with the opening click; (2) closing the mouth along the protrusive border movement path; (3) contacting the teeth in the protruded position; (4) retruding to a contact position just before the click; and (5) opening the mouth maximally again without the opening click. This exercise was repeated for 5 minutes before each meal, and the patient must maintain the disk repositioning mandibular position all day if possible. Repositioning splints were used to keep the disk repositioning mandible position during sleeping. Arthrocentesis was performed for patients who did not experience improvement and for cases wherein troubles in daily life were predicted to shorten the treatment period greatly. Patients who experienced the complete cessation of locking and absence of clicking during palpation were defined as in the effective group, and patients who had no change in the frequency of locking or progressed to permanent lock were defined as in the ineffective group. In addition, the longevity of the curative effect was judged 3 months after each medical treatment began. Data analysis The clinical data, the treatment method, and the clinical outcome were collected retrospectively from the patients’ records. The clinical parameters included pain on clicking and masticatory pain. We compared the MRI findings between the patients with and without intermittent closed lock by using Fisher’s exact test and Pearson’s chi-square test. The clinical and MRI findings of the effective group were compared with those of the ineffective group. A comparison examination of both groups was statistically carried out at the time of the initial visit by using Fisher’s exact test. Statistical analysis was performed using SPSS 18.0 (SPSS, Chicago, IL). A Pvalue of .05 was considered statistically significant.
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Fig. 1. The degree of anterior disk displacement. 1, Slight. 2, Moderate.3, Severe.
RESULTS In TMJs with intermittent closed lock, 23 of the 58 joints (39.7%) were characterized by slight anterior disk displacement, 31 joints (53.4%) were moderate, and 4 joints (6.9%) were severe. In TMJs without intermittent closed lock, 308 of the 526 joints (58.6%) were characterized by slight anterior disk displacement, 209 joints (39.7%) were moderate, and 9 joints (1.7%) were severe. The difference in the degree of anterior displacement between the groups was not statistically significant. In TMJs with intermittent closed lock, 34 of the 58 joints (58.6%) had typical anterior disk displacement, and 24 of the 58 joints (41.4%) had rotational anterior displacement with an associated sideways shift. In TMJs without intermittent closed lock, 308 of the 526 joints (58.6%) had typical anterior disk displacement, and 215 of the 526 joints (41.4%) had rotational anterior displacement with an associated sideways shift. There was no significant difference in the frequency of occurrence of sideways displacement between the groups. In TMJs with intermittent closed lock, 26 of the 58 joints (44.8%) exhibited disk deformity, compared with 118 of the 526 joints (22.4%) in TMJs without intermittent closed lock. The prevalence of disk deformity
between the 2 groups was significantly different (P < .001) (Table II). The patients who improved through the disk repositioning exercises alone included 4 joints. Thirty-seven cases improved through a combination of disk repositioning exercises and a repositioning splint. No improvements were observed in 2 joints that had undergone arthrocentesis. The total efficacy rate for intermittent lock was 82.8% (Table III). While comparing the clinical and MRI findings of the effective group and ineffective group, masticatory muscle pain was observed in 20 of the 48 TMJs (41.7%) in the effective group and in 8 of the 10 TMJs (80.0%) in the ineffective group. Therefore, the masticatory muscle pain was significantly more common in the ineffective group than in the effective group (P ¼ .03). In contrast, there was no significant difference in displacement or deformation of the disk between the groups (Table IV).
DISCUSSION This retrospective study of temporomandibular joint intermittent closed lock revealed a possible relationship among the onset of intermittent closed lock, disk deformation, and degree of anterior placement. When intermittent closed lock patients were divided into
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Fig. 2. Disk deformity.1, Enlargement of posterior band. 2, Folding. 3, Biplanner. 4, Biconvex.
2groups based on the efficacy of treatment, masticatory muscle pain was significantly more common in the ineffective group than in the effective group. Although intermittent closed lock generally involves a reduction in disk displacement, temporary trismus without reduction may be presented too. Intermittent closed lock is a relatively rare pathologic condition with a variety of clinical features; consequently, there are many unclear points regarding its etiology. In joints with no disk displacement, articular disk deformation is rarely seen; however, based on the pathologic progression of internal derangement, various differences may be found, such as disk deformation, degree of displacement, and orientation. Westesson et al.7 and de Leeuw et al.11 reported on the relationship between the degree of displacement and disk deformation in disk displacement found in the temporomandibular joint. Westesson et al.7 classified articular disk formation into 5 categories: biconcave, reversed, enlargement of posterior band, biplanar, and biconvex. As a result of examining the relationship with the pathology of
internal derangement, they found articular disk deformation in 64 out of 77 joints with anterior displacement without reduction. Furthermore, in patients diagnosed with internal derangement, Almas¸an et al.12 classified 74 joints into 3 groups: normal disk position (31 joints), anterior disk displacement with reduction (27 joints), and anterior disk displacement without reduction (16 joints). After assessing the disk formation in each group, they reported that disk deformation afflicted 16 joints (51.7%) in the normal disk position group, 26 joints (96.3%) in the anterior disk displacement with reduction group, and all joints with anterior disk displacement without reduction. On the basis of these findings, it is believed that disk deformation tends to develop as the degree of anterior disk displacement progresses and that it occurs at a high rate. Reports indicate that lateral disk placement is significantly higher in intermittent closed lock cases than in cases of anterior disk displacement with reduction and without intermittent closed lock13; further reports claim that anterior disk displacement contributes to intermittent
ORAL AND MAXILLOFACIAL SURGERY 422 Takahara et al.
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Table II. MRI findings of the joints with and without intermittent closed lock Variable Degree of anterior disk displacement Slight Moderate Severe Sideways displacement Disk deformity
Joints with ICL (N ¼ 58)
23 31 4 24 26
Joints without ICL (N ¼ 526)
(39.7%) (53.4%) (6.9%) (41.4%) (44.8%)
308 209 9 215 118
(58.6%) (39.7%) (1.7%) (40.9%) (22.4%)
P value
.002*
.524 < .001y
ICL, intermittent closed lock; MRI, magnetic resonance imaging. *Pearson’s chi-square test. y Fisher’s exact test.
Table III. Therapeutic effect of the patients with intermittent closed lock Treatment method DR exercise DR exercise þARS therapy DR exercise þARS therapy þArthrocentesis Total
Effective
Ineffective
4
0
37
8
7
2
48 (82.8%)
10 (17.2%)
ARS, anterior repositioning splint therapy; DR, disk repositioning.
Table IV. Clinical and MRI findings of the effective group and the ineffective group with intermittent closed lock Effective group Ineffective group (N ¼ 48) (N ¼ 10) P Value Pain at clicking Masticatory pain Degree of anterior disk displacement Slight Moderate Severe Sideways displacement Disk deformity
20 (41.7%) 20 (41.7%)
3 (30%) 8 (80%)
.377 .03*
18 27 3 21 23
5 4 1 3 3
.636
(37.5%) (56.3%) (6.2%) (43.8%) (39.6%)
(50%) (40%) (10%) (30%) (30%)
.331 .248
MRI, magnetic resonance imaging. *Fisher’s exact test.
closed lock more than disk deformation contributes to it.14 In the present study, we found disk deformation in 44.8% of the joints in the group with intermittent closed lock and in 22.4% in the group without intermittent closed lock. We also found that disk deformation was significantly higher in the group with intermittent closed lock. Furthermore, we found that the anterior placement of the disk tended to be advanced in the group with intermittent closed lock. This suggests that there is a relationship among the onset of intermittent closed lock, disk deformation, and degree of anterior placement.
The disk and condylar translation pathway have a complex impact on intermittent closed lock and may lead to situations where reduction is not possible. Becauseintermittent closed lock is the intermediate pathologic condition of the click and closed lock, the onset of closed lock should be prevented while aiming to improve the pain and discomfort of the click. Disk repositioning exercises8 and splint therapy are considered effective for the click. These therapies aim to reposition and adapt the displaced disk and are believed to be useful in the prevention of closed lock. Treatments offered byour department for intermittent closed lock include the disk repositioning exercise,8 anterior repositioning splint,9 and arthrocentesis.10 We generally opt for disk repositioning exercises, which work well in conjunction with anterior repositioning splint therapy. We perform arthrocentesis for patients who do not improve with the combined therapy or for patients who wish to reduce the duration of the treatment, because treatment does cause a major disturbance to daily life activities. Yoda et al.5 conducted a multifacility survey on the clinical features and outcomes of intermittent closed lock by examining the therapeutic outcomes of disk repositioning exercise alone and the combined therapy of disk repositioning exercises with anterior repositioning splint. They reported that the symptom disappeared in 41.7% of the participants who underwent diskrepositioning exercises alone and in 60% of the participants who underwent diskrepositioning exercises with the anterior repositioning splint. For the present study, only 4 of the patients we reviewed underwent disk repositioning exercises alone; most patients chose to receive an anterior repositioning splint with the disk repositioning exercises, and the response rate of this combined therapy was 75.5%. Therefore, we believe that disk repositioning exercises with the anterior repositioning splint is a valid primary treatment for intermittent closed lock. Moreover, arthrocentesis was additionally performed for 9 cases because the combination of disk repositioning exercises and repositioning splint was ineffective in these cases. An improvement was observed in 7 of these 9 cases (77.8%). Regarding the effects of arthrocentesis, Nitzan et al.10 described the reduced viscosity of synovial fluid and the removal of the vacuum effect between the disk and the mandible fossa, which improves the translation motility of the disk and is believed to improve the symptoms of intermittent closed lock. Therefore, arthrocentesis is indicated for intermittent closed lock when disk repositioning exercises and repositioning splints have been ineffective. As we compared the clinical and MRI findings of the effective group and ineffective group, we noticed that masticatory muscle pain was significantly more common in the ineffective group than in the effective group.
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However, no significant difference was observed in the placement or deformation of the disk between the both groups. Therefore, not only should the muscle be treated directly in intermittent closed lock, but the muscle tension should also be eased. REFERENCES 1. Wilkes CH. Internal derangements of temporomandibularjoint pathologic variations. Arch Otolaryngol Head Necksurg. 1989;115:469-477. 2. Okeson JP. Long-term treatment of disk-interference disordersof the temporomandibular joint with anterior repositioningocclusal splints. J Prosthet Dent. 1988;60:611-616. 3. Friedman MH. Closed lock. A survey of 400 cases. Oralsurg Oral Medoral Pathol Oral Radiol Endod. 1993;75:422-427. 4. Dworkin SF, LeResche L. Research diagnostic criteria fortemporomandibular disorders: Review, criteria, examinations andspecifications, critique. J Craniomandib Disord. 1992;6: 301-355. 5. Yoda T, Sakamoto I, Imai H, et al. Response of temporomandibular joint intermittent closed lock to different treatment modalities:a multicenter survey. Cranio. 2006;24:130-136. 6. Tasaki MM, Westesson PL. Temporomandibular joint: diagnostic accuracy with sagittal and coronal MR imaging. Radiology. 1993;186:723-729. 7. Westesson PL, Bronstein SL, Liedberg J. Internal derangement of the temporomandibular joint:morphologic description withcorrelation to joint function. Oral Surg Oral Med Oral Pathol. 1985;59:323-331. 8. Yoda T, Sakamoto I, Imai H, et al. A randomized controlled trial of therapeuticexercise for clicking due to disk anteriordisplacement with reduction in the temporomandibular joint. Cranio. 2003;21:10-16.
ORIGINAL ARTICLE Takahara et al. 423 9. Kurita H, Kurashina K, Baba H, Ohtsuka A, Kotani A, Kopp S. Evaluation of disk capture with a splint repositioning appliance: clinical and critical assessment with MR imaging. Oral Surg Oralmed Oral Pathol Oral Radiol Endod. 1998;85:377-380. 10. Nitzan DW, Dolwick MF, Martinez GA. Temporomandibular joint arthrocentesis: a simplified treatment for severe, limited mouth opening. J Oral Maxillofac Surg. 1991;49:1163-1167. 11. de Leeuw R, Boering G, Stegenga B, de Bont LG. TMJ articular disc position and configuration 30 y after initial diagnosis of internal derangement. J Oral Maxillofac Surg. 1995;53:234-242. 12. Almas¸an OC, Hedes¸iu M, Baciut¸ G, Leucut¸a DC, Baciut¸ M. Disk and jointmorphologyvariations on coronal and sagittal MRI in temporomandibular joint disorders. Clin Oral Investig. 2013;17: 1243-1250. 13. Aomura T, Matsuo T, Adachi A, Mizuki H. Association between the direction of disc displacement and intermittent lock in the temporomandibular joint. J Jpn Soc TMJ. 2004;16:141-145. 14. Ide T, Nagai I, Miyazaki A, Yamaguchi A, Kohama G. Clinical study of intermittent lock of the temporomandibular joint:relation to frequency of intermittent lock on clinical examination and magnetic resonance imaging. Jpn J Oral Maxillofac Surg. 2002;48:191-194.
Reprint requests: Namiaki Takahara, DDS Department of Oral and Maxillofacial Surgery Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University 1-5-45, Yushima, Bunkyo-ku Tokyo 113-8549 Japan [email protected]