Annika Isberg

Classification and prevalence of temporomandibular joint disk displacement in patients and symptom-free volunteers

The purposes of this study were to develop a classification system for disk displacement in the temporomandibular joint (TMJ) and to study the prevalence of the various types of TMJ disk displacement in patients and symptom-free volunteers. The study was based on bilateral MRIs of 243 patients and 57 symptom-free volunteers. Eight different types of disk displacements were identified in addition to the superior disk position and a tenth indeterminate category. Superior disk position was observed bilaterally in 18% of the patients and bilaterally in 70% of the symptom-free volunteers.

Internal derangement of the temporomandibular joint: radiographic and histologic changes associated with severe pain.

In 20 temporomandibular joints (TMJs) (15 patients) with internal derangement associated with severe pain, the presurgical radiographic findings were compared with the morphologic and histologic alterations. Disc extirpation was performed in 17 joints, and in three joints the disc was surgically repositioned. Deformation of the disc observed by double-contrast arthrotomography was verified histologically. Perforation of the posterior disc attachment was seen in two joints; both were associated with osteophyte formation and flattening of the articular eminence. The white disc-like structure in 11 cases was composed of an anterior, stiff, bulgy, biconvex structure combined with a posterior flattened portion that grossly was incorrectly determined to be part of the disc, but that was identified histologically as a posterior disc attachment that had undergone adaptive change characterized by connective tissue hyalinization. In the arthrotomogram the disc position could easily be determined. However, the disc-like clinical appearance of the posterior disc attachment in these cases made determination of disc position at surgery uncertain or impossible. The nonhyalinized posterior disc attachment was intensely red and showed advanced histologic alterations of the vessels, deposits of extravasated erythrocytes and fibrin, and altered composition of the connective tissue. Thus, signs of inflammation were present but without activation of the local immune system since no major inflammatory cell infiltrates were seen. Small accumulations of lymphocytes were seen in only two cases. The surgically extirpated posterior attachments were innervated by silver-positive nerve fibers ranging in diameter from 1 to 15 micron. The severe pain in the TMJs is likely to have originated from this innervated posterior disc attachment or capsule and to have been triggered by the vascular reaction.

Mandibular coronoid process locking: A prospective study of frequency and association with internal derangement of the temporomandibular joint☆

Coronoid process locking has been regarded a rare condition. The literature reveals 59 reports each of one or two cases and an additional two papers reporting on four and six patients, respectively, the latter including hereditary cases. Coronoid process elongation tends to be overlooked when limitation of mouth-opening ability is investigated, since most interest is focused on the joint. To study the frequency of coronoid process hyperplasia and its possible association with TMJ disk displacement, 163 patients with limited mouth-opening ability were examined. All patients were referred for radiographic examination of the TMJs. In eight patients (5%), the limitation of mouth-opening ability was caused by elongation of the coronoid process. Four cases were of congenital origin, and four were secondary to long-standing disk displacement without reduction. The results of this study indicate that elongation of the coronoid process is more common than previously thought. In cases of limited mouth opening, attention should be paid to the possibility of coronoid process locking.

Hyperplastic soft-tissue formation in the temporomandibular joint associated with internal derangement: A radiographic and histologic study☆

Hyperplastic connective tissue formation in the posterior part of the temporomandibular joint glenoid fossa has previously been described in autopsy specimens. The frequency of such hyperplastic tissue formation in patients with long-standing temporomandibular joint pain was studied in 103 joints from 80 patients by means of double-contrast arthrotomography. Five joints in four patients (5%) demonstrated hyperplastic tissue formation; in four cases this was associated with permanently displaced and deformed disks. All five joints were refractory to nonsurgical treatment. Surgically extirpated hyperplastic tissue and disk attachments contained nerve fibers and thickened adventitia of vessels, resulting in narrowed or obliterated lumina, extravasated erythrocytes, and fibrinlike deposits. The synovial membrane showed fibrinoid necrosis or was lost. The pain reaction in temporomandibular joints with hyperplastic soft-tissue formation may be released by compression or tension of nerves, breaking down products from blood or tissue ischemia. Contrast filling of both joint spaces, combined with tomography, was required for detection of the hyperplastic tissue formation.

Clinical, radiographic, and electromyographic study of patients with internal derangement of the temporomandibular joint

Fifteen patients with internal derangement of the temporomandibular joint (TMJ) were examined clinically, radiographically, and electromyographically. Electromyographic recordings were also obtained from 11 subjects without signs or symptoms associated with their TMJs or masticatory musculature. All the patients with internal derangement demonstrated interferences on the ipsilateral side. This was interpreted as the result of disc displacement producing a reduced joint space and, consequently, a decreased vertical dimension on the symptomatic side. Slow opening and closing mandibular movements without clenching could be performed by healthy persons without noticeable EMG activity in the temporalis and masseter muscles. In association with disc displacement, electromyographic activity of the temporalis and masseter muscles occurred when the condyle slid over the posterior band of the disc and could be interpreted as an arthrokinetic reflex caused by distraction. Continuous muscle activity could be provoked by TMJ disc displacement and ceased when the disc position was normalized on mouth opening, only to occur again every time the disc became displaced on mouth closure. Anterior disc displacement without reduction (closed lock) could cause spastic activity in the temporalis muscle on the affected side. Spastic activity of the masseter and temporalis muscles occurring on the same side as a joint with anterior disc displacement hinders or inhibits the condylar movement necessary to achieve reduction.

Tissue reactions associated with internal derangement of the temporomandibular joint: A radiographic, cryomorphologic, and histologic study

Ten temporomandibular joint specimens, five with clinical signs of arthropathology and five without, were examined by means of tomography, double-contrast tomography, and serial cryosectioning combined with histologic staining of sections for tissue identification. Of the five joints with signs of arthropathology four demonstrated disc displacement. The fifth joint showed a post-traumatic condition. Four of the joints with clinical signs of arthropathology demonstrated hyperplastic connective tissue retaining contrast medium in the posterior part of the fossa. This hyperplastic connective tissue contained extravasated blood and enlarged cavernous structures lacking endothelial lining. Extravasated blood is one probable source of temporomandibular joint pain. All joints with permanently displaced discs demonstrated perforation of a hyalinized posterior disc attachment. Without tissue identification such an attachment is likely to be misinterpreted as being the disc itself.

Salivary calculi and chronic sialoadenitis of the submandibular gland: a radiographic and histologic study.

This study correlated radiographic observations and histologic findings of submandibular glands with the diagnosis of salivary calculus and/or chronic sialoadenitis. During a 15-year period eighty-eight patients satisfied clinical requirements by having a radiographic examination performed prior to gland extirpation. Salivary calculi were present in 83% of the patients. The diagnostic accuracy of radiographs regarding salivary calculi in the submandibular gland system was 92%. Radiolucent calculi constituted 20% of the total number of cases with concrements. Failure to disclose concrements was caused by lack of contrast filling due to a damaged gland which presumably camouflaged radiolucent concretions. Ductal changes observed in sialograms corresponded to histologic changes in the glandular parenchyma in 96% of the cases. The absence of ductal change in sialograms did not necessarily indicate a nondiseased gland.

Coronoid process elongation in rhesus monkeys (Macaca mulatta) after experimentally induced mandibular hypomobility: A cephalometric and histologic study☆

The present study provided an experimental model that allowed a cephalometric and histologic analysis of craniofacial growth in monkeys with induced translatory impairment of the mandibular condyle. Cauterization was performed anterior to the joint in nine experimental rhesus monkeys, while eight animals served as control subjects. The experimental procedure produced mandibular hypomobility in six animals, in three by means of temporomandibular joint ankylosis and in three by means of dense scar tissue formation anterior to the joint. In the remaining three experimental animals no restriction of mandibular mobility was created. Mandibular hypomobility was found to induce elongation of the coronoid process and was also associated with bone deposition in the gonial region. In contrast, normal remodeling of the gonial region was found in the experimental animals with normal range of movements and in the control animals.

Lingual numbness and speech articulation deviation associated with temporomandibular joint disk displacement

A prospective investigation of 208 patients with painful, arthrographically verified temporomandibular joint disk displacement revealed that seven patients (3%) demonstrated lingual numbness associated with speech articulation impairment. The speech disorder was characterized primarily by a distortion in the production of /s,r,d, and t/. The lingual numbness and the speech disorder had in all cases started in association with a painful onset of permanent displacement of the temporomandibular joint disk. Local anesthetic blocking of the auriculotemporal nerve eliminated both joint pain and muscle pain and normalized tongue sensitivity and speech articulation. Placebo injections of saline solution resulted in no change. The explanation of the phenomenon is that the course of the lingual nerve for these seven patients was through the lateral pterygoid muscle rather than mesial to the muscle bundles and that an arthrokinetic myospasm resulted in compression of the lingual nerve. In order to test the hypothesis that the condition of lingual nerve entrapment in the lateral pterygoid muscle does exist, the course of the nerve was studied at dissection in 52 specimens from 26 cadaver heads. In 49 of the specimens, the lingual nerve descended deep to the lateral pterygoid muscle as has been traditionally defined. However, in three specimens, the nerve passed through the inferior belly of the muscle, revealing the condition of lingual nerve entrapment.

A cephalometric analysis of patients with coronoid process enlargement and locking

Two patient groups with radiographically verified coronoid process locking were cephalometrically examined. In eight patients the locking was of congenital origin, and in eight patients the locking had developed as a result of internal derangement of the temporomandibular joint. When compared with that in a control group, the height of the coronoid process was statistically significantly greater in both patient groups, but there was no difference on condylar height between any of the groups. Neither were there any differences between groups regarding the upper face height, which, if present, could have been expected to contribute to the development of coronoid process locking. In the group with congenital enlargement, the mandibular configuration was strikingly square-shaped, which was expressed by a statistically significantly smaller gonion angle than was present in the other two groups. The finding was interpreted as a growth effect due to the mandibular locking.