TMJ Subluxation (Anterior Dislocation of the Temporomandibular Joint)

1. Definition and Anatomy

2. Etiology and Predisposing Factors

• Extreme mouth opening - yawning, prolonged dental procedures, endoscopy, intubation, laughing
• Trauma - direct blow or impact (more likely to cause fracture-dislocation)
• Anatomic predisposition - disharmony between the mandibular fossa and articular eminence, weak or torn capsular/temporomandibular ligaments
• Dystonic drug reactions - antipsychotics (phenothiazines, metoclopramide) causing jaw dystonia
• Previous dislocation - patients who have had one episode are predisposed to recurrence
• Hyperlaxity conditions - Ehlers-Danlos syndrome, Marfan syndrome

3. Pathophysiology

4. Clinical Features

• Inability to close the mouth (locked open jaw)
• Significant pain and distress
• Drooling and difficulty handling secretions
• Garbled speech (inability to touch tongue to palate/maxillary teeth)
• Difficulty chewing

• Jaw fixed in open/protrusive position
• Preauricular depression - a visible and palpable hollow just anterior to the tragus where the condyle normally sits
• Bilateral dislocation - symmetrical jaw protrusion (most common)
• Unilateral dislocation - jaw deviates to the opposite side (away from the affected joint)
• Apparent underbite due to anterior mandibular displacement
• Tenderness on palpation of the affected TMJ region

5. Diagnosis

• The diagnosis is usually clinical based on history and examination alone
• Radiographs (Panorex/OPG, or facial CT) are indicated when:
  • Traumatic mechanism is suspected (to exclude fracture-dislocation before manipulation)
  • Diagnosis is uncertain
  • Reduction is difficult or painful beyond expectation
• Routine radiographs are NOT needed for straightforward, atraumatic presentations

6. Management

A. Pre-reduction

• Adequate analgesia and sedation are essential - masseter spasm makes unaided reduction very difficult
• Local anesthesia option: inject 2 mL of 2% lidocaine into the preauricular depression just anterior to the tragus (into the joint space) to relax the masseter
• IV benzodiazepine (diazepam) or procedural sedation may be used for resistant cases

B. Reduction Techniques

• Patient seated upright with head against a firm surface
• Operator stands in front, wraps thumbs in gauze for protection, places thumbs over the occlusal surfaces of the mandibular molars (as far posterior as possible)
• Fingers wrap beneath the angle and body of the mandible
• Apply firm, progressive downward and backward pressure with the thumbs; fingers simultaneously rotate the chin upward and backward
• The condyle clears the articular eminence and muscles contract returning the jaw to closed position (panel E)
• Caution: wrap thumbs with gauze - the jaw snaps shut with tremendous force upon reduction

• Patient and operator both seated
• Thumbs placed on the mentum (chin) applying upward force
• Fingers placed on the lower molars applying downward force
• Operator flexes the wrist, rotating the mandible so the condyle descends inferiorly and slips back into the mandibular fossa

• Provider stands in front; places thumb on the patient's cheek over the mandibular ramus/coronoid process
• Applies persistent posterior pressure
• Fingers placed behind the angle of the mandible to stabilize
• Opposite hand applies anterior pull on the contralateral mandibular angle
• This maneuver rotates the jaw and facilitates reduction of the opposite side

7. Post-reduction Care

• Patient should be able to close mouth immediately after successful reduction
• Soft diet for 1 week
• Restrict mouth opening to <2 cm for 2 weeks
• Advise patient to support the chin with a hand when yawning
• Warm compresses to the TMJ area
• NSAIDs for analgesia; muscle relaxants may help
• Postreduction radiographs generally not required unless the procedure was difficult, traumatic, or pain is unexplained
• Barton bandage (elastic bandage wrapping under the chin and over the skull) for chronic or recurrent dislocators to restrict opening
• Elective referral to an oral/maxillofacial surgeon

8. Complications and Indications for Surgical Referral

• Iatrogenic mandibular fracture
• Avulsion of articular cartilage
• Bite injury to operator's fingers

• Open dislocation
• Superior dislocation
• Dislocation associated with fracture
• Neurological injury
• Irreducible dislocation by closed technique

• Eminectomy (removal of the articular eminence)
• Intermaxillary fixation (IMF) wiring
• Capsule/ligament plication procedures

Summary Table

Odontogenic Keratocyst (OKC) / Keratocystic Odontogenic Tumor (KCOT)

1. Definition and Nomenclature

• First described by Philipsen in 1956 as "odontogenic keratocyst"
• In 2005, the WHO reclassified it as Keratocystic Odontogenic Tumor (KCOT) due to its aggressive biological behavior and neoplastic features
• The 2017 WHO Classification reverted the term back to Odontogenic Keratocyst (OKC), though it is still classified under ICD-11 as an odontogenic tumor
• Both terms OKC and KCOT are currently used interchangeably

2. Incidence and Age / Sex Distribution

• Accounts for approximately 10-11% of all jaw cysts
• Peak incidence: 2nd and 3rd decades of life (but may occur at any age)
• Male predominance (M:F ratio approximately 1.5-2:1)
• May be associated with Gorlin-Goltz (Basal Cell Nevus) Syndrome when multiple cysts are present

3. Site of Occurrence

• Mandible is more commonly affected than the maxilla (ratio 3:1)
• Within the mandible, most common site: angle and ramus area (mandibular third molar region)
• Can occur in any area of odontogenesis: pericoronal, periradicular, interradicular, or apical positions
• Maxillary lesions, though less common, are often more difficult to treat

4. Clinical Features

• The lesion is often asymptomatic and discovered incidentally on routine radiograph
• When symptomatic, may present with:
  • Swelling - often minimal despite large cyst size (grows anteroposteriorly within the medullary bone without significant buccal expansion)
  • Pain - dull aching, especially if secondarily infected
  • Trismus (restricted mouth opening) when ramus is involved
  • Paresthesia or numbness of the lower lip (involvement of the inferior alveolar nerve)
  • Tooth displacement or loosening of adjacent teeth
  • Purulent discharge from an associated sinus tract in infected cases

• Grows predominantly anteroposteriorly along the medullary canal with minimal cortical expansion
• Hence can reach a very large size before being detected
• Daughter/satellite cysts may be present in the cyst wall - a major reason for recurrence
• The cyst fluid appears cheesy or white due to keratin (unlike the amber-colored fluid of dentigerous cyst)

5. Radiographic Features

• Well-defined radiolucency with well-corticated/sclerotic margins
• May be unilocular (more common in small lesions) or multilocular (honeycomb or soap-bubble appearance in large lesions)
• Scalloped borders between roots are characteristic
• Bowing of the inferior border of the mandible without significant cortical expansion
• Often associated with an impacted or displaced tooth (pericoronal location)
• Root resorption is less common than in other cysts
• Calcification within the cyst wall is rare; the lesion is predominantly radiolucent
• CT scan is essential for large lesions, particularly in the maxilla, to assess extent

6. Histopathological Features

7. Differential Diagnosis

• Dentigerous cyst (pericoronal location, less aggressive)
• Ameloblastoma (multilocular, more cortical expansion)
• Lateral periodontal cyst
• Residual cyst / Radicular cyst
• Traumatic bone cavity
• Giant cell lesion

8. Pathogenesis and Reasons for Recurrence

1. Satellite/daughter cysts in the cyst wall left behind at surgery
2. Incomplete removal of the thin, friable epithelial lining
3. Dental lamina rests in the overlying mucosa giving rise to new cysts
4. Collagenase activity of the cyst lining promotes bone destruction
5. Prostaglandin-induced bone resorption
6. Increased mitotic activity of the epithelium (supports neoplastic behavior)
7. Recurrences often appear within 5 years but can occur up to 40 years later

9. Association with Gorlin-Goltz Syndrome (Basal Cell Nevus Syndrome - BCNS)

• Multiple OKCs of the jaws (often first manifestation)
• Multiple basal cell carcinomas of skin (appear at a young age)
• Calcification of the falx cerebri (on skull radiograph/CT)
• Bifid ribs, skeletal anomalies
• Frontal bossing, hypertelorism
• Medulloblastoma (desmoplastic variant)

10. Treatment

Conservative Treatment:

1. Enucleation alone - for small, non-recurrent lesions; high recurrence rate
2. Enucleation + Carnoy's solution - Carnoy's solution (absolute alcohol, chloroform, glacial acetic acid) applied to the bony cavity for 3 minutes after enucleation to fix and destroy residual epithelial remnants; reduces recurrence; most commonly recommended method
3. Enucleation + peripheral ostectomy (bone burring) - mechanical removal of 1-2 mm of bony cavity wall
4. Marsupialization (Partsch I procedure) - for large cysts near vital structures; decompresses the cyst allowing the cavity to reduce in size before definitive enucleation; reduces recurrence by causing epithelial maturation and thickening

Aggressive Treatment (for large/recurrent lesions):

1. Resection (marginal or segmental) with reconstruction - reserved for very large lesions, recurrent cases, or cases with perforation into adjacent structures
2. En-bloc resection with immediate reconstruction using titanium plates or bone graft

Post-operative:

• Regular radiographic follow-up for minimum 5 years (ideally 10 years due to late recurrences)
• Annual OPG/Panorex for 5 years, then every 2-3 years thereafter

Summary Table