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Temporomandibular Joint Condylar Abnormality: Evaluation, Treatment Planning, and Surgical Approach
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J Oral Maxillofac Surg 68:1189-1196, 2010
Temporomandibular Joint Condylar Abnormality: Evaluation, Treatment Planning, and Surgical Approach Jaqueline S. Venturin, DDS,* Werner H. Shintaku, DDS, MS,† Yuko Shigeta, DDS, PhD,‡ Takumi Ogawa, DDS, PhD,§ Bach Le, DDS, MD,储 and Glenn T. Clark, DDS, MS¶ The cartilage of the mandibular condyle is located beneath the fibrous articular layer and undergoes atrophic changes, assuming endochondral bone growth or adaptive growth, according to the absence or presence of functional demand. Normal condylar growth follows a sequence of transitory stages that are defined by molecules synthesized by undifferentiated mesenchymal cells and differentiating chondrocytes.1 For example, Sox 9 transcription factor is expressed by cells in the proliferative layer and chondrocytes. It is a potent activator of type II collagen, the main type of collagen that forms the framework of the cartilage matrix in the growing condyle.2 Type X collagen is expressed only by hypertrophic chondrocytes, and its
*Assistant Professor, Division of Health Promotion, Disease Prevention and Epidemiology, University of Southern California School of Dentistry, Los Angeles, CA †Resident, Dental Diagnostic Science, University of Texas Health Science Center at San Antonio Dental School, San Antonio, TX. ‡Assistant Professor, Department of Fixed Prosthodontic Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan. §Assistant Professor, Department of Fixed Prosthodontic Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan. 储Clinical Associate Professor, Department of Oral and Maxillofacial Surgery, University of Southern California School of Dentistry, Los Angeles, CA. ¶Program Director and Professor, Orofacial Pain and Oral Medicine Center, Division of Diagnostic Sciences, University of Southern California School of Dentistry, Los Angeles, CA. Address correspondence and reprint requests to Dr Venturin: Division of Health Promotion, Disease Prevention and Epidemiology, Special Patients’ Care, University of Southern California School of Dentistry, 925 West 34th Street, Room DEN 4202, Los Angeles, CA 90089; e-mail: [email protected] © 2010 American Association of Oral and Maxillofacial Surgeons
0278-2391/10/6805-0040$36.00/0 doi:10.1016/j.joms.2009.08.002
expression precedes the onset of endochondral ossification. It is involved in the growth, development, and remodeling of the articular cartilage.3,4 Vascular endothelial growth factor is expressed by hypertrophic chondrocytes, and its maximal level of expression precedes the maximal level of bone formation. It regulates the neovascularization of the hypertrophic cartilage and influences the removal of the cartilage matrix. The invading blood vessels bring osteogenic progenitor mesenchymal cells into the mineralization front that later differentiate into osteoblasts that engage in osteogenesis.5 Both during jaw growth and after it has stopped, the mandibular condyle is continuously under the influence of extrinsic forces, which can be physiologic, functional, or excessive, such as with macrotraumas and microtraumas. It is also important to consider the natural aging process, the genetic mechanisms that might determine the reaction of the normal tissues to become abnormal, and even the idiopathic apposition of abnormal or tumor cells.6,7 Alterations or disruptions in the developmental process can happen in the early stages of formation and can be isolated malformations or a part of a syndrome.8 Alterations in growth produce anomalies in size, described as condylar hypoplasia or condylar hyperplasia, abnormalities of shape such as a bifid or trifid condyle, and tumors, which can be benign or malignant. When a patient presents with progressive facial asymmetry, a thorough clinical evaluation and diagnostic tests with proper imaging techniques are indicated. The clinical differential diagnosis for these growth disorders of the condyle or ramus includes developmental and neoplastic conditions such as condylar hyperplasia, osteochondroma, chondroblastoma, osteoma, osteoblastoma, and chondrosarcoma (Table 1).9-13 Panoramic radiography and computed tomography (CT) of the temporomandibular joint (TMJ) will show an enlarged condyle and a longer mandibular neck on the affected side; however, they cannot provide information
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Table 1. COMPARISON OF DEVELOPMENTAL AND NEOPLASTIC CONDITIONS CONSIDERED IN OVERGROWTH OF THE MANDIBULAR CONDYLE
Differential Diagnosis Unilateral condylar hyperplasia8-10 Osteochondroma9,11
Chondroblastoma9,11,12
Osteoma9,12,13
Osteoblastoma9,11,12
Chondrosarcoma11-13
Clinical Findings
Radiographic Findings
Histologic Findings
Open bite; chin deviation toward Enlarged condyle; normal Chondrocyte proliferation during unaffected side; cross bite cortical thickness and initial and active phases, with might or might not be present trabecular pattern normal bone after growth ceases Facial asymmetry with chin Radiopaque mass, no Bony mass, cap of fibrocartilage, deviation, malocclusion, destructive features; hyaline cartilage, fibrous tissue palpable hard mass in affected globular pattern; distorted of perichondrium, endochondral TMJ condylar shape ossification Swelling and limited mandibular Well-defined radiolucency Proliferating cells, centric or motion with sclerotic margin, eccentric nuclei, giant cells, inner flocculent cartilage differentiation, radiopacities immature cartilaginous matrix, calcifications around chondroblasts Spherical or lobular Dense lamellar cortical Interlaced osteoid strands, enlargements, asymptomatic bone, well circumscribed; vascularized fibrous stroma, hard swelling occasionally with osteoblasts, and osteoclasts cancellous form Swelling and tenderness, usually Well-circumscribed solitary Large or irregular trabeculae, associated with trauma lesions that expand multinucleated osteoclast-like within medullary cavity cells, and osteoblasts with ample cytoplasm and hyperchromatic nuclei, loose fibrous connective tissue with dilated vascular channels Slow-growing and usually lowSingle or multiple Mesenchymal stem cells with grade pattern; preauricular radiolucency; bone partial chondroblastic swelling, pain, limited mouth destruction with mottled differentiation, lobular growth, opening, mandibular drift, and densities hypercellularity with diminished hearing pleomorphism, and malignant cartilage
Abbreviation: TMJ, temporomandibular joint. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
regarding whether the abnormal growth is still active. A comparison of follow-up images might provide enough information to assess the tumor growth. However, if a more immediate answer is needed, techniques such as skeletal scintigraphy using technetium-99m methylene diphosphate, which can be used with single photon emission CT, or positron emission tomography (PET) using a radiolabeled glucose analog, 18F-2-fluoro-2-deoxyglucose (FDG), as a tracer, alone or combined with CT (PET/CT), might indicate increased cellular activity on the affected side. Scintigraphy, single photon emission CT, and PET are useful to identify the presence of a growth center and to determine whether an active process is present.14 The combination of morphologic and physiologic imaging modalities offers improved analysis of benign and malignant lesions. However, it is important to consider that FDG uptake occurs in any site with a physiologically high glucose metabolism, such as the brain, liver, spleen, bowel, and tonsils. Sites with inflammation and infection can also result in increased uptake, making the assessment of abnormal activity sometimes problematic.15
One recent study examined whether planar bone scintigraphy was able to distinguish sarcomatous changes in osteochondromas (cartilaginous exostoses).16 They examined 22 histologically verified cases of chondrosarcoma and osteochondroma using technetium-99m bone scintigraphy. They did not find any significant differences in tracer uptake between the 2 conditions, leading them to question the efficacy of planar bone scintigraphy to distinguish benign osteochondromas from malignant chondrosarcomas. FDG-PET has been increasingly used for the identification and differentiation of malignant and benign bone lesions.17,18 A group of researchers evaluated the accuracy of PET to verify whether FDG uptake in cartilage tumors would correctly correlate with the histopathologic tumor grade.19 They examined 35 biopsy-proven cartilaginous tumor samples using plain radiographs, bone scanning, magnetic resonance imaging, and PET. Grades 2 and 3 chondrosarcomas had significantly greater uptake than did low-grade cartilaginous tumors; however, PET alone was not able to differentiate benign
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had become more evident during the previous 4 months. The patient reported that before that period he had had a comfortable bite that had been achieved with orthodontic treatment during childhood. He also reported episodic clicking in the left TMJ, sporadic ringing and stuffiness in the left ear, daily headaches, and episodic migraines that had became aggravated throughout the same period. No history of trauma, no relevant concomitant systemic problem, and no other joint presented with signs of abnormality. However, he did present with the habits of tooth clenching and grinding and was already using a night guard. CLINICAL EXAMINATION
FIGURE 1. Patient’s facial profile at first appointment. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
cartilage tumors from grade 1 chondrosarcomas (P ⫽ .009; positive-predictive value 0.82 and negative predictive value 0.96). Therefore, these investigators still advocated biopsy to establish the final diagnosis. Any structural abnormality in the TMJ should be thoroughly evaluated. Using the currently available technology, the imaging systems are able to supply a good amount of information for the assessment of these abnormalities. Multiplanar reconstructions and 3-dimensional models using the data acquired by cone-beam CT (CBCT) or CT scans contribute information not only for detailed evaluation, but also provide an accurate visual perspective for the efficient diagnosis and treatment planning with a better prediction of the final outcome.
The first step in the assessment of facial asymmetry is to conduct a thorough head and neck examination. In our patient, facial asymmetry was evident, with chin deviation to the left side, and enlargement noted on the right preauricular region (Fig 1). No lymphadenopathy was noted. The otoscopic examination findings were normal for the auditory canal, pinna, and tympanic membrane. Muscle palpation revealed moderate to severe pain bilaterally on the masticatory and postural muscles, with severe pain noted on palpation of the bilateral TMJs. The intraoral examination revealed no dental attrition and generally good oral health. Significant malocclusion was observed secondary to mandible posture deviation to the anterior, and lateral to the left position. Only the left central incisors were in contact in the maximal intercuspal position, resulting in a bilateral posterior open bite with an anterior edge-to-edge relation, and the midline with a mandibular deviation to the left of 4 mm. The teeth were well aligned within the arches, and the alveolar bone in both upper and lower arches presented with the anatomic characteristics preserved. This indicated that no deformities had developed in a natural attempt to accommodate the occlusion to this abnormal jaw position, contributing to the conclusion that the patient’s situation had been recently established (Fig 2). Six months later, the clinical examination revealed changes in the mandibular position with an anterior cross bite and increased pain in the TMJ area. The patient could not move his jaw backward to the initial edge-to-edge position possible at the initial examination, because this movement was interrupted by rigid ending and severe pain in the right TMJ. These findings suggested that his condition was an ongoing process. This information is important for the treatment planning (Fig 3). The mandibular mobility examination revealed painfree opening of 40 mm. Active opening reached 55 mm,
Report of a Case CHIEF COMPLAINT AND HISTORY OF PRESENT ILLNESS A 20-year-old man presented with a chief complaint of bilateral TMJ pain, facial asymmetry, and bite shifting that had progressively increased within a 2-year period and
FIGURE 2. Occlusal condition at first appointment. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 3. Occlusal condition 6 months after initial visit. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
which induced pain on the left side of the face. Excursive movements were more affected, and he could move only 5 mm to the right, 2 mm to the left, and 2 mm to the protrusive, with all movements provoking pain in the left TMJ. No TMJ noises were present during the examination. The midline was deviated to the left when the mouth was closed. However, on opening, it acquired a more centered position. The left condyle was able to rotate and translate, but the right condyle was only able to perform translational movement. PANORAMIC RADIOGRAPHIC EXAMINATION Because the clinical findings were highly indicative of structural involvement of the right TMJ, the second step in our workup was panoramic radiography. The panoramic radiograph showed a right condyle with an increased size and abnormal shape. The left condyle had a normal size and shape, with no evidence of degenerative changes (Fig 4). CBCT WITH 3D RECONSTRUCTION For a better assessment of the involved structures, the third step was to acquire a CBCT scan (Newtom 3G, Verona, Italy) of the jaws and face (volume size 20 cm, voxel size 0.3 mm). An irregular, globular-shaped mass was noted on the anterior aspect of the lateral pole of the right condyle (Fig 5). The internal structure of the lesion was of a uniform greater density with the medial one half of the condyle having normal bone density. The articular eminence revealed moderate bone remodeling. In the
FIGURE 5. Axial CBCT reconstruction. Note irregular outline of right condyle. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
closed position, owing to the overgrowth, the condyle was displaced downward and forward outside the mandibular fossa. On opening, the condyle translated well past the articular eminence. On the left side, the cortical outlines of the condyle, mandibular fossa, and articular eminence were within normal limits. In the closed position, the condyle was concentrically located within the mandibular fossa, and, on opening, the condyle translated past the eminence. The 3D reconstruction of the CBCT data using specific imaging software (Amira; Visage Imaging, San Diego, CA) confirmed the extensive abnormal growth of the right condyle, with an irregular contour and expansion suggestive of a benign tumor lesion rather than condylar hyperplasia. The absence of aggressive infiltration and bone destruction reinforced the indication of a benign process rather than a malignant condition (Fig 6). PET/CT SCAN The fourth step in our workup involved PET/CT to verify the lesion activity. Multi-axial images through the head,
FIGURE 4. Initial radiographic assessment with panoramic radiography.
FIGURE 6. Three-dimensional reconstruction. Note difference between condylar outlines.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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To better analyze the altered structures and plan the surgical procedure, we used 3D images to develop a virtual simulation model in which we could remove the lesion, preserve a portion of the condyle, and then place the condyle back into the fossa to determine whether this manipulation would provide reasonable interdigitation of the teeth (Fig 8). Derived from the CBCT data, stereolithographic models were fabricated with and without the tumorous mass. This also enabled surgical excision simulation (Fig 9). THERAPY
FIGURE 7. PET/CT scan showing lack of tracer uptake in region of interest. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
neck, chest, abdomen, and pelvis were obtained for review after CT attenuation correction. No abnormal hyperactivity was demonstrated in the right condyle to suggest a highly metabolically active condition (Fig 7). Normal tonsillar, bowel, and urinary uptake was observed, as well as normal uptake in the brown fat in the neck and mediastinal and paravertebral regions.
The patient was admitted to University of Southern California University Hospital for surgical removal of the tumor. The electrocardiographic and chest radiographic findings and routine urine and blood values were within normal limits. The tumor resection and reshaping of the mandibular condyle was planned using 3D imaging. The precise amount of resection needed to achieve the patient’s preoperative occlusion was determined using 3D reconstruction of the relationship between the patient’s condylar tumor and resulting malocclusion (Figs 6, 8). A preauricular approach was created to access the condylar head. A high condylectomy was performed as planned (Fig 10). A piece of the condyle (with the tumor) was removed (Fig 11) and sent for histologic identification. The occlusion was verified clinically after conservative resection and reshaping of the condyle. Guiding elastics were maintained for 2 weeks postoperatively. Microscopic examination confirmed the diagnosis of osteochondroma. At 6 months of follow-up, the patient presented with good facial symmetry and a stable occlusal relationship. The mandibular function was excellent, with a maximal incisal opening of 35 to 40 mm. A panoramic radiograph revealed good symmetry of the mandible and a favorable condylar shape
FIGURE 8. Simulation models. Three-dimensional models showing A, tumor lesion and B, after surgical exicision. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 11. Tumor specimen sent for histologic evaluation. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
FIGURE 9. Stereolithographic model of right TMJ. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
(Fig 12). The radiographic follow-up data were obtained using small-volume CBCT (Accuitomo; J Morita, Kyoto, Japan) for increased image resolution and a reduced radiation dose to the patient (Fig 13).
Discussion Considering the history of the illness and the clinical and radiographic findings from the panoramic and CBCT images, we suspected a benign neoplasm (most likely an osteochondroma). Osteochondroma is a benign bone tumor that arises from the endochon-
dral bone and can present as a solitary lesion (75%) or as multiple lesions (25%). It represents 35% of all benign tumors and 8.5% of all bone tumors. It is rarely found in the oral and maxillofacial region. However, the occurrence in the condyle seems to be the most common site in the facial region. Osteochondroma has been suggested to have a female predilection and has a wide age range of 11 to 69 years. However, some reports have also reported no gender predominance and a peak age of about the fourth decade.20,21 The risk of malignant transformation is about 1% for solitary lesions. However, we have found no cases of conversion to malignancy reported for tumors in the mandibular condyle region. The risk of recurrence of this benign lesion is low after surgical removal; however, the only recurrence reported in published studies resulted from incomplete excision.22 The signs and symptoms associated with osteochondroma of the condyle vary according to the size and location of the growth. The lesion usually arises
FIGURE 10. Condylectomy of right condyle.
FIGURE 12. Panoramic radiograph after surgical procedure.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 13. CBCT scan of right TMJ after condylectomy. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
from the medial anterior aspect of the condylar neck and extends to the condylar head. Radiographically, the lesion can be visualized as a radiopaque mass without lytic features, with a globular pattern with altered condylar morphology. The histopathologic characteristics consist of a proliferative bony mass covered by a cap of fibrocartilage and hyaline cartilage surrounded by the fibrous tissue of the perichondrium, and endochondral ossification in the deepest aspect of the cartilage.12,17,23 The chondrocytes can form rows that are perpendicular to the surface of the lesion, and they can overlie a zone of endochondral ossification, resulting in fusion of the cancellous bone with the normal underlying bone. Calcification of the cartilage and ossification might be seen, and older lesions will have a thinner rim of cartilage owing to extensive replacement by bone.24 Given the dimensions reached by the growth, the therapeutic approach recommended is typically surgery. Several techniques have been suggested in published reports, and the decision must take into consideration the shape and size of the lesion, any resulting deformities or impingement on other structures, and the functional morbidity it has caused.20,25 The procedures can involve conservative approaches or more extensive measures according to the surgical findings, but complete excision of the lesion is considered the standard. Some surgeons have used a condylectomy (77% of the time), followed by excision of the lesion, preserving the condyle (23% of the
time).19 The condylectomy can be partial or complete.26,27 Operating in the TMJ area is challenging. However, the data reported to date have not supported corrective orthognathic surgery of the maxillary and/or mandibular arches without accessing the tumor to confirm the histopathologic diagnosis. Surgery of small benign tumors of the condyle requires a subperiosteal resection through a preauricular access. Larger lesions with breaching of the periosteum require condylectomy. Attempts to use arthroscopic surgery in specific situations are under investigation but have not been proved.24 After tumor excision, with or without condylar preservation, complementary correction of the facial and/or occlusal asymmetry might be required and can involve a separate orthognathic procedure and subsequent orthodontic treatment. In cases of full condylectomy and subcondylar process extension, a costochondral graft or artificial joint prosthetic reconstruction is recommended. The prognosis is good, and the published data have demonstrated no evidence of recurrence at 7 months, 20 months, and 5 years.18,20,28 The aim of the present report was to describe the importance of using a comprehensive model to assess the progressive facial asymmetry and to emphasize the use of 3D reconstruction in planning the tumor surgery and how it affects the treatment planning, operative time, and prognosis. The treatment planning for our case was all done using 3D CBCT reconstructed images. This included determination of the anatomy of the surgical area, the surgical access method, and the amount of surgical resection needed. Using 3D reconstruction, the tumor was conservatively resected and the condyle was left intact, leaving no postoperative sequelae. All the patient’s preoperative problems resolved, and patient presented with 3-mm midline deviation to the right on opening at 6 months of follow-up. A comprehensive evaluation of our patient involved the history reported and the clinical findings, correlated with the panoramic, CBCT, and PET/CT findings. Using these data, we recommended surgical management, including tumor excision, with condylar reshaping or high condylectomy. We used the CBCT data to create a 3D virtual model that could be manipulated and repositioned such that we could visualize the final postoperative occlusion. Although the clinical and imaging data were suggestive of a benign lesion, the diagnosis could only be confirmed by histopathologic examination of the surgical specimen, confirming the diagnosis of osteochondroma of the TMJ condyle.
References 1. Shen G, Hagg U, Rabie AB, et al: Identification of temporal pattern of mandibular condylar growth: A molecular and biochemical experiment. Orthod Craniofac Res 8:114, 2005
1196 2. Rabie AB, Hagg U: Factors regulating mandibular condylar growth. Am J Orthod Dentofac Orthop 122:401, 2002 3. Shen G: The role of type X collagen in facilitating and regulating endochondral ossification of articular cartilage. Orthod Craniofac Res 8:11, 2005 4. Kwan KM, Pang MK, Zhou S, et al: Abnormal compartmentalization of cartilage matrix components in mice lacking collagen X: Implications for function. J Cell Biol 136:459, 1997 5. Bi W, Deng JM, Zhang Z, et al: Sox9 is required for cartilage formation. Nat Genet 22:85, 1999 6. Hylander WL: Functional anatomy and biomechanics of the masticatory apparatus, in Laskin DM, Greene CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment (ed 1). Chicago, Quintessence Publishing, 2006, p 3 7. Stegenga B, Bont LGM: TMJ growth, adaptive modeling and remodeling, and compensatory mechanisms, in Laskin DM, Greene CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment (ed 1). Chicago, Quintessence Publishing, 2006, p 53 8. Neville BW, Damm DD, Allen CM, et al: Developmental defects of the oral and maxillofacial region, in Neville BW, Damm DD, Allen CM, et al (eds): Oral and Maxillofacial Pathology (ed 2). Philadelphia, WB Saunders, 2002, p 1 9. Petrikowski CG: Diagnostic imaging of the temporomandibular joint, in White SC, Pharoah MJ (eds): Oral Radiology (ed 5). Philadelphia, Mosby, 2004, p 538 10. Troulis MJ, Kaban LB: Congenital and developmental anomalies, in Laskin DM, Green, CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment. Chicago, Quintessence Publishing, 2006, p 421 11. Neville BW, Damm DD, Allen CM, et al: Bone pathology, in Neville BW, Damm DD, Allen CM, et al (eds): Oral and Maxillofacial Pathology (ed 2). Philadelphia, WB Saunders, 2002, p 533 12. Stern D: Benign and malignant tumors, in Laskin DM, Green, CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment. Chicago, Quintessence Publishing, 2006, p 319 13. Batra PS, Estrem SA, Zitsch RP, et al: Chondrosarcoma of the temporomandibular joint. Otolaryngol Head Neck Surg 120: 961, 1999 14. Rosenbaum SJ, Lind T, Antoch G, et al: False-positive FDG PET uptake—The role of PET/CT. Eur Radiol 16:1054, 2006 15. Henderson MJ, Wastie ML, Bromige M, et al: Technetium-99m bone scintigraphy and mandibular condylar hyperplasia. Clin Radiol 41:411, 1990
TMJ CONDYLAR ABNORMALITY 16. Hendel HW, Daugaard S, Kjaer A: Utility of planar bone scintigraphy to distinguish benign osteochondromas from malignant chondrosarcomas. Clin Nucl Med 27:622, 2002 17. Cham DK, Conti PS: Normal physiology and variants: A primer, in Conti PS, Cham DK (eds): PET-CT: A Case-Based Approach. New York, Springer, 2005, p 3 18. Dehdashti F, Siegel BA, Griffeth LK, et al: Benign versus malignant intraosseous lesions: Discrimination by means of PET with 2-[F-18] fluoro-2-deoxy-D-glucose. Radiology 200: 243, 1996 19. Lee FY, Yu J, Chang SS, et al: Diagnostic value and limitations of fluorine-18 fluorodeoxyglucose positron emission tomography for cartilaginous tumors of bone. J Bone Joint Surg Am 86A:2677, 2004 20. Saito T, Utsunomiya T, Furutani M, et al: Osteochondroma of the mandibular condyle: A case report and review of the literature. J Oral Sci 43:293, 2001 21. Khochtali H, Bouzaiene M, Yacoubi MT, et al: Osteochondroma of the mandibular condyle: Apropos of a case. Rev Stomatol Chir Maxillofac 94:87, 1993 22. Vezeau PJ, Fridrich KL, Vincent SD: Osteochondroma of the mandibular condyle: Literature review—A report of two atypical cases. J Oral Maxillofac Surg 53:954, 1995 23. Koga M, Toyofuku S, Nakamura Y, et al: Osteochondroma in the mandibular condyle that caused facial asymmetry: A case report. Cranio 24:67, 2006 24. Karras CS, Wolford LM, Cottrell DA: Concurrent osteochondroma of the mandibular condyle and ipsilateral cranial base resulting in temporomandibular joint ankylosis: Report of case and review of the literature. J Oral Maxillofac Surg 54:640, 1996 25. Iizuka T, Schroth G, Laeng RH, et al: Osteochondroma of the mandibular condyle: Report of a case. J Oral Maxillofac Surg 54:495, 1996 26. Wolford LM, Mehra P, Franco P: Use of conservative condylectomy for treatment of osteochondroma of the mandibular condyle. J Oral Maxillofac Surg 60:262, 2002 27. Clayman L: Surgical management of benign and malignant neoplasms, in Laskin DM, Greene CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment. Chicago, Quintessence Publishing, 2006, p 509 28. Holmlund AB, Gynther GW, Reinholt FP: Surgical treatment of osteochondroma of the mandibular condyle in the adult: A 5-year follow-up. Int J Oral Maxillofac Surg 33:549, 2004
VENTURIN ET AL
J Oral Maxillofac Surg 68:1189-1196, 2010
Temporomandibular Joint Condylar Abnormality: Evaluation, Treatment Planning, and Surgical Approach Jaqueline S. Venturin, DDS,* Werner H. Shintaku, DDS, MS,† Yuko Shigeta, DDS, PhD,‡ Takumi Ogawa, DDS, PhD,§ Bach Le, DDS, MD,储 and Glenn T. Clark, DDS, MS¶ The cartilage of the mandibular condyle is located beneath the fibrous articular layer and undergoes atrophic changes, assuming endochondral bone growth or adaptive growth, according to the absence or presence of functional demand. Normal condylar growth follows a sequence of transitory stages that are defined by molecules synthesized by undifferentiated mesenchymal cells and differentiating chondrocytes.1 For example, Sox 9 transcription factor is expressed by cells in the proliferative layer and chondrocytes. It is a potent activator of type II collagen, the main type of collagen that forms the framework of the cartilage matrix in the growing condyle.2 Type X collagen is expressed only by hypertrophic chondrocytes, and its
*Assistant Professor, Division of Health Promotion, Disease Prevention and Epidemiology, University of Southern California School of Dentistry, Los Angeles, CA †Resident, Dental Diagnostic Science, University of Texas Health Science Center at San Antonio Dental School, San Antonio, TX. ‡Assistant Professor, Department of Fixed Prosthodontic Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan. §Assistant Professor, Department of Fixed Prosthodontic Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan. 储Clinical Associate Professor, Department of Oral and Maxillofacial Surgery, University of Southern California School of Dentistry, Los Angeles, CA. ¶Program Director and Professor, Orofacial Pain and Oral Medicine Center, Division of Diagnostic Sciences, University of Southern California School of Dentistry, Los Angeles, CA. Address correspondence and reprint requests to Dr Venturin: Division of Health Promotion, Disease Prevention and Epidemiology, Special Patients’ Care, University of Southern California School of Dentistry, 925 West 34th Street, Room DEN 4202, Los Angeles, CA 90089; e-mail: [email protected] © 2010 American Association of Oral and Maxillofacial Surgeons
0278-2391/10/6805-0040$36.00/0 doi:10.1016/j.joms.2009.08.002
expression precedes the onset of endochondral ossification. It is involved in the growth, development, and remodeling of the articular cartilage.3,4 Vascular endothelial growth factor is expressed by hypertrophic chondrocytes, and its maximal level of expression precedes the maximal level of bone formation. It regulates the neovascularization of the hypertrophic cartilage and influences the removal of the cartilage matrix. The invading blood vessels bring osteogenic progenitor mesenchymal cells into the mineralization front that later differentiate into osteoblasts that engage in osteogenesis.5 Both during jaw growth and after it has stopped, the mandibular condyle is continuously under the influence of extrinsic forces, which can be physiologic, functional, or excessive, such as with macrotraumas and microtraumas. It is also important to consider the natural aging process, the genetic mechanisms that might determine the reaction of the normal tissues to become abnormal, and even the idiopathic apposition of abnormal or tumor cells.6,7 Alterations or disruptions in the developmental process can happen in the early stages of formation and can be isolated malformations or a part of a syndrome.8 Alterations in growth produce anomalies in size, described as condylar hypoplasia or condylar hyperplasia, abnormalities of shape such as a bifid or trifid condyle, and tumors, which can be benign or malignant. When a patient presents with progressive facial asymmetry, a thorough clinical evaluation and diagnostic tests with proper imaging techniques are indicated. The clinical differential diagnosis for these growth disorders of the condyle or ramus includes developmental and neoplastic conditions such as condylar hyperplasia, osteochondroma, chondroblastoma, osteoma, osteoblastoma, and chondrosarcoma (Table 1).9-13 Panoramic radiography and computed tomography (CT) of the temporomandibular joint (TMJ) will show an enlarged condyle and a longer mandibular neck on the affected side; however, they cannot provide information
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Table 1. COMPARISON OF DEVELOPMENTAL AND NEOPLASTIC CONDITIONS CONSIDERED IN OVERGROWTH OF THE MANDIBULAR CONDYLE
Differential Diagnosis Unilateral condylar hyperplasia8-10 Osteochondroma9,11
Chondroblastoma9,11,12
Osteoma9,12,13
Osteoblastoma9,11,12
Chondrosarcoma11-13
Clinical Findings
Radiographic Findings
Histologic Findings
Open bite; chin deviation toward Enlarged condyle; normal Chondrocyte proliferation during unaffected side; cross bite cortical thickness and initial and active phases, with might or might not be present trabecular pattern normal bone after growth ceases Facial asymmetry with chin Radiopaque mass, no Bony mass, cap of fibrocartilage, deviation, malocclusion, destructive features; hyaline cartilage, fibrous tissue palpable hard mass in affected globular pattern; distorted of perichondrium, endochondral TMJ condylar shape ossification Swelling and limited mandibular Well-defined radiolucency Proliferating cells, centric or motion with sclerotic margin, eccentric nuclei, giant cells, inner flocculent cartilage differentiation, radiopacities immature cartilaginous matrix, calcifications around chondroblasts Spherical or lobular Dense lamellar cortical Interlaced osteoid strands, enlargements, asymptomatic bone, well circumscribed; vascularized fibrous stroma, hard swelling occasionally with osteoblasts, and osteoclasts cancellous form Swelling and tenderness, usually Well-circumscribed solitary Large or irregular trabeculae, associated with trauma lesions that expand multinucleated osteoclast-like within medullary cavity cells, and osteoblasts with ample cytoplasm and hyperchromatic nuclei, loose fibrous connective tissue with dilated vascular channels Slow-growing and usually lowSingle or multiple Mesenchymal stem cells with grade pattern; preauricular radiolucency; bone partial chondroblastic swelling, pain, limited mouth destruction with mottled differentiation, lobular growth, opening, mandibular drift, and densities hypercellularity with diminished hearing pleomorphism, and malignant cartilage
Abbreviation: TMJ, temporomandibular joint. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
regarding whether the abnormal growth is still active. A comparison of follow-up images might provide enough information to assess the tumor growth. However, if a more immediate answer is needed, techniques such as skeletal scintigraphy using technetium-99m methylene diphosphate, which can be used with single photon emission CT, or positron emission tomography (PET) using a radiolabeled glucose analog, 18F-2-fluoro-2-deoxyglucose (FDG), as a tracer, alone or combined with CT (PET/CT), might indicate increased cellular activity on the affected side. Scintigraphy, single photon emission CT, and PET are useful to identify the presence of a growth center and to determine whether an active process is present.14 The combination of morphologic and physiologic imaging modalities offers improved analysis of benign and malignant lesions. However, it is important to consider that FDG uptake occurs in any site with a physiologically high glucose metabolism, such as the brain, liver, spleen, bowel, and tonsils. Sites with inflammation and infection can also result in increased uptake, making the assessment of abnormal activity sometimes problematic.15
One recent study examined whether planar bone scintigraphy was able to distinguish sarcomatous changes in osteochondromas (cartilaginous exostoses).16 They examined 22 histologically verified cases of chondrosarcoma and osteochondroma using technetium-99m bone scintigraphy. They did not find any significant differences in tracer uptake between the 2 conditions, leading them to question the efficacy of planar bone scintigraphy to distinguish benign osteochondromas from malignant chondrosarcomas. FDG-PET has been increasingly used for the identification and differentiation of malignant and benign bone lesions.17,18 A group of researchers evaluated the accuracy of PET to verify whether FDG uptake in cartilage tumors would correctly correlate with the histopathologic tumor grade.19 They examined 35 biopsy-proven cartilaginous tumor samples using plain radiographs, bone scanning, magnetic resonance imaging, and PET. Grades 2 and 3 chondrosarcomas had significantly greater uptake than did low-grade cartilaginous tumors; however, PET alone was not able to differentiate benign
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had become more evident during the previous 4 months. The patient reported that before that period he had had a comfortable bite that had been achieved with orthodontic treatment during childhood. He also reported episodic clicking in the left TMJ, sporadic ringing and stuffiness in the left ear, daily headaches, and episodic migraines that had became aggravated throughout the same period. No history of trauma, no relevant concomitant systemic problem, and no other joint presented with signs of abnormality. However, he did present with the habits of tooth clenching and grinding and was already using a night guard. CLINICAL EXAMINATION
FIGURE 1. Patient’s facial profile at first appointment. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
cartilage tumors from grade 1 chondrosarcomas (P ⫽ .009; positive-predictive value 0.82 and negative predictive value 0.96). Therefore, these investigators still advocated biopsy to establish the final diagnosis. Any structural abnormality in the TMJ should be thoroughly evaluated. Using the currently available technology, the imaging systems are able to supply a good amount of information for the assessment of these abnormalities. Multiplanar reconstructions and 3-dimensional models using the data acquired by cone-beam CT (CBCT) or CT scans contribute information not only for detailed evaluation, but also provide an accurate visual perspective for the efficient diagnosis and treatment planning with a better prediction of the final outcome.
The first step in the assessment of facial asymmetry is to conduct a thorough head and neck examination. In our patient, facial asymmetry was evident, with chin deviation to the left side, and enlargement noted on the right preauricular region (Fig 1). No lymphadenopathy was noted. The otoscopic examination findings were normal for the auditory canal, pinna, and tympanic membrane. Muscle palpation revealed moderate to severe pain bilaterally on the masticatory and postural muscles, with severe pain noted on palpation of the bilateral TMJs. The intraoral examination revealed no dental attrition and generally good oral health. Significant malocclusion was observed secondary to mandible posture deviation to the anterior, and lateral to the left position. Only the left central incisors were in contact in the maximal intercuspal position, resulting in a bilateral posterior open bite with an anterior edge-to-edge relation, and the midline with a mandibular deviation to the left of 4 mm. The teeth were well aligned within the arches, and the alveolar bone in both upper and lower arches presented with the anatomic characteristics preserved. This indicated that no deformities had developed in a natural attempt to accommodate the occlusion to this abnormal jaw position, contributing to the conclusion that the patient’s situation had been recently established (Fig 2). Six months later, the clinical examination revealed changes in the mandibular position with an anterior cross bite and increased pain in the TMJ area. The patient could not move his jaw backward to the initial edge-to-edge position possible at the initial examination, because this movement was interrupted by rigid ending and severe pain in the right TMJ. These findings suggested that his condition was an ongoing process. This information is important for the treatment planning (Fig 3). The mandibular mobility examination revealed painfree opening of 40 mm. Active opening reached 55 mm,
Report of a Case CHIEF COMPLAINT AND HISTORY OF PRESENT ILLNESS A 20-year-old man presented with a chief complaint of bilateral TMJ pain, facial asymmetry, and bite shifting that had progressively increased within a 2-year period and
FIGURE 2. Occlusal condition at first appointment. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 3. Occlusal condition 6 months after initial visit. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
which induced pain on the left side of the face. Excursive movements were more affected, and he could move only 5 mm to the right, 2 mm to the left, and 2 mm to the protrusive, with all movements provoking pain in the left TMJ. No TMJ noises were present during the examination. The midline was deviated to the left when the mouth was closed. However, on opening, it acquired a more centered position. The left condyle was able to rotate and translate, but the right condyle was only able to perform translational movement. PANORAMIC RADIOGRAPHIC EXAMINATION Because the clinical findings were highly indicative of structural involvement of the right TMJ, the second step in our workup was panoramic radiography. The panoramic radiograph showed a right condyle with an increased size and abnormal shape. The left condyle had a normal size and shape, with no evidence of degenerative changes (Fig 4). CBCT WITH 3D RECONSTRUCTION For a better assessment of the involved structures, the third step was to acquire a CBCT scan (Newtom 3G, Verona, Italy) of the jaws and face (volume size 20 cm, voxel size 0.3 mm). An irregular, globular-shaped mass was noted on the anterior aspect of the lateral pole of the right condyle (Fig 5). The internal structure of the lesion was of a uniform greater density with the medial one half of the condyle having normal bone density. The articular eminence revealed moderate bone remodeling. In the
FIGURE 5. Axial CBCT reconstruction. Note irregular outline of right condyle. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
closed position, owing to the overgrowth, the condyle was displaced downward and forward outside the mandibular fossa. On opening, the condyle translated well past the articular eminence. On the left side, the cortical outlines of the condyle, mandibular fossa, and articular eminence were within normal limits. In the closed position, the condyle was concentrically located within the mandibular fossa, and, on opening, the condyle translated past the eminence. The 3D reconstruction of the CBCT data using specific imaging software (Amira; Visage Imaging, San Diego, CA) confirmed the extensive abnormal growth of the right condyle, with an irregular contour and expansion suggestive of a benign tumor lesion rather than condylar hyperplasia. The absence of aggressive infiltration and bone destruction reinforced the indication of a benign process rather than a malignant condition (Fig 6). PET/CT SCAN The fourth step in our workup involved PET/CT to verify the lesion activity. Multi-axial images through the head,
FIGURE 4. Initial radiographic assessment with panoramic radiography.
FIGURE 6. Three-dimensional reconstruction. Note difference between condylar outlines.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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To better analyze the altered structures and plan the surgical procedure, we used 3D images to develop a virtual simulation model in which we could remove the lesion, preserve a portion of the condyle, and then place the condyle back into the fossa to determine whether this manipulation would provide reasonable interdigitation of the teeth (Fig 8). Derived from the CBCT data, stereolithographic models were fabricated with and without the tumorous mass. This also enabled surgical excision simulation (Fig 9). THERAPY
FIGURE 7. PET/CT scan showing lack of tracer uptake in region of interest. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
neck, chest, abdomen, and pelvis were obtained for review after CT attenuation correction. No abnormal hyperactivity was demonstrated in the right condyle to suggest a highly metabolically active condition (Fig 7). Normal tonsillar, bowel, and urinary uptake was observed, as well as normal uptake in the brown fat in the neck and mediastinal and paravertebral regions.
The patient was admitted to University of Southern California University Hospital for surgical removal of the tumor. The electrocardiographic and chest radiographic findings and routine urine and blood values were within normal limits. The tumor resection and reshaping of the mandibular condyle was planned using 3D imaging. The precise amount of resection needed to achieve the patient’s preoperative occlusion was determined using 3D reconstruction of the relationship between the patient’s condylar tumor and resulting malocclusion (Figs 6, 8). A preauricular approach was created to access the condylar head. A high condylectomy was performed as planned (Fig 10). A piece of the condyle (with the tumor) was removed (Fig 11) and sent for histologic identification. The occlusion was verified clinically after conservative resection and reshaping of the condyle. Guiding elastics were maintained for 2 weeks postoperatively. Microscopic examination confirmed the diagnosis of osteochondroma. At 6 months of follow-up, the patient presented with good facial symmetry and a stable occlusal relationship. The mandibular function was excellent, with a maximal incisal opening of 35 to 40 mm. A panoramic radiograph revealed good symmetry of the mandible and a favorable condylar shape
FIGURE 8. Simulation models. Three-dimensional models showing A, tumor lesion and B, after surgical exicision. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 11. Tumor specimen sent for histologic evaluation. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
FIGURE 9. Stereolithographic model of right TMJ. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
(Fig 12). The radiographic follow-up data were obtained using small-volume CBCT (Accuitomo; J Morita, Kyoto, Japan) for increased image resolution and a reduced radiation dose to the patient (Fig 13).
Discussion Considering the history of the illness and the clinical and radiographic findings from the panoramic and CBCT images, we suspected a benign neoplasm (most likely an osteochondroma). Osteochondroma is a benign bone tumor that arises from the endochon-
dral bone and can present as a solitary lesion (75%) or as multiple lesions (25%). It represents 35% of all benign tumors and 8.5% of all bone tumors. It is rarely found in the oral and maxillofacial region. However, the occurrence in the condyle seems to be the most common site in the facial region. Osteochondroma has been suggested to have a female predilection and has a wide age range of 11 to 69 years. However, some reports have also reported no gender predominance and a peak age of about the fourth decade.20,21 The risk of malignant transformation is about 1% for solitary lesions. However, we have found no cases of conversion to malignancy reported for tumors in the mandibular condyle region. The risk of recurrence of this benign lesion is low after surgical removal; however, the only recurrence reported in published studies resulted from incomplete excision.22 The signs and symptoms associated with osteochondroma of the condyle vary according to the size and location of the growth. The lesion usually arises
FIGURE 10. Condylectomy of right condyle.
FIGURE 12. Panoramic radiograph after surgical procedure.
Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
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FIGURE 13. CBCT scan of right TMJ after condylectomy. Venturin et al. TMJ Condylar Abnormality. J Oral Maxillofac Surg 2010.
from the medial anterior aspect of the condylar neck and extends to the condylar head. Radiographically, the lesion can be visualized as a radiopaque mass without lytic features, with a globular pattern with altered condylar morphology. The histopathologic characteristics consist of a proliferative bony mass covered by a cap of fibrocartilage and hyaline cartilage surrounded by the fibrous tissue of the perichondrium, and endochondral ossification in the deepest aspect of the cartilage.12,17,23 The chondrocytes can form rows that are perpendicular to the surface of the lesion, and they can overlie a zone of endochondral ossification, resulting in fusion of the cancellous bone with the normal underlying bone. Calcification of the cartilage and ossification might be seen, and older lesions will have a thinner rim of cartilage owing to extensive replacement by bone.24 Given the dimensions reached by the growth, the therapeutic approach recommended is typically surgery. Several techniques have been suggested in published reports, and the decision must take into consideration the shape and size of the lesion, any resulting deformities or impingement on other structures, and the functional morbidity it has caused.20,25 The procedures can involve conservative approaches or more extensive measures according to the surgical findings, but complete excision of the lesion is considered the standard. Some surgeons have used a condylectomy (77% of the time), followed by excision of the lesion, preserving the condyle (23% of the
time).19 The condylectomy can be partial or complete.26,27 Operating in the TMJ area is challenging. However, the data reported to date have not supported corrective orthognathic surgery of the maxillary and/or mandibular arches without accessing the tumor to confirm the histopathologic diagnosis. Surgery of small benign tumors of the condyle requires a subperiosteal resection through a preauricular access. Larger lesions with breaching of the periosteum require condylectomy. Attempts to use arthroscopic surgery in specific situations are under investigation but have not been proved.24 After tumor excision, with or without condylar preservation, complementary correction of the facial and/or occlusal asymmetry might be required and can involve a separate orthognathic procedure and subsequent orthodontic treatment. In cases of full condylectomy and subcondylar process extension, a costochondral graft or artificial joint prosthetic reconstruction is recommended. The prognosis is good, and the published data have demonstrated no evidence of recurrence at 7 months, 20 months, and 5 years.18,20,28 The aim of the present report was to describe the importance of using a comprehensive model to assess the progressive facial asymmetry and to emphasize the use of 3D reconstruction in planning the tumor surgery and how it affects the treatment planning, operative time, and prognosis. The treatment planning for our case was all done using 3D CBCT reconstructed images. This included determination of the anatomy of the surgical area, the surgical access method, and the amount of surgical resection needed. Using 3D reconstruction, the tumor was conservatively resected and the condyle was left intact, leaving no postoperative sequelae. All the patient’s preoperative problems resolved, and patient presented with 3-mm midline deviation to the right on opening at 6 months of follow-up. A comprehensive evaluation of our patient involved the history reported and the clinical findings, correlated with the panoramic, CBCT, and PET/CT findings. Using these data, we recommended surgical management, including tumor excision, with condylar reshaping or high condylectomy. We used the CBCT data to create a 3D virtual model that could be manipulated and repositioned such that we could visualize the final postoperative occlusion. Although the clinical and imaging data were suggestive of a benign lesion, the diagnosis could only be confirmed by histopathologic examination of the surgical specimen, confirming the diagnosis of osteochondroma of the TMJ condyle.
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TMJ CONDYLAR ABNORMALITY 16. Hendel HW, Daugaard S, Kjaer A: Utility of planar bone scintigraphy to distinguish benign osteochondromas from malignant chondrosarcomas. Clin Nucl Med 27:622, 2002 17. Cham DK, Conti PS: Normal physiology and variants: A primer, in Conti PS, Cham DK (eds): PET-CT: A Case-Based Approach. New York, Springer, 2005, p 3 18. Dehdashti F, Siegel BA, Griffeth LK, et al: Benign versus malignant intraosseous lesions: Discrimination by means of PET with 2-[F-18] fluoro-2-deoxy-D-glucose. Radiology 200: 243, 1996 19. Lee FY, Yu J, Chang SS, et al: Diagnostic value and limitations of fluorine-18 fluorodeoxyglucose positron emission tomography for cartilaginous tumors of bone. J Bone Joint Surg Am 86A:2677, 2004 20. Saito T, Utsunomiya T, Furutani M, et al: Osteochondroma of the mandibular condyle: A case report and review of the literature. J Oral Sci 43:293, 2001 21. Khochtali H, Bouzaiene M, Yacoubi MT, et al: Osteochondroma of the mandibular condyle: Apropos of a case. Rev Stomatol Chir Maxillofac 94:87, 1993 22. Vezeau PJ, Fridrich KL, Vincent SD: Osteochondroma of the mandibular condyle: Literature review—A report of two atypical cases. J Oral Maxillofac Surg 53:954, 1995 23. Koga M, Toyofuku S, Nakamura Y, et al: Osteochondroma in the mandibular condyle that caused facial asymmetry: A case report. Cranio 24:67, 2006 24. Karras CS, Wolford LM, Cottrell DA: Concurrent osteochondroma of the mandibular condyle and ipsilateral cranial base resulting in temporomandibular joint ankylosis: Report of case and review of the literature. J Oral Maxillofac Surg 54:640, 1996 25. Iizuka T, Schroth G, Laeng RH, et al: Osteochondroma of the mandibular condyle: Report of a case. J Oral Maxillofac Surg 54:495, 1996 26. Wolford LM, Mehra P, Franco P: Use of conservative condylectomy for treatment of osteochondroma of the mandibular condyle. J Oral Maxillofac Surg 60:262, 2002 27. Clayman L: Surgical management of benign and malignant neoplasms, in Laskin DM, Greene CS, Hylander WL (eds): Temporomandibular Disorders: An Evidence-Based Approach to Diagnosis and Treatment. Chicago, Quintessence Publishing, 2006, p 509 28. Holmlund AB, Gynther GW, Reinholt FP: Surgical treatment of osteochondroma of the mandibular condyle in the adult: A 5-year follow-up. Int J Oral Maxillofac Surg 33:549, 2004