CC
A 26-year-old female presents seeking treatment to correct her skeletal malocclusion. She has noticed that her chin has been receding since her teenage years and that her bite has been worsening as well. She has a remote history of pain in her temporomandibular joints (TMJs) but is currently asymptomatic, with no other symptoms in her TMJs.
Patients with idiopathic condylar resorption (ICR) are typically identified at the orthodontist’s office or at the oral and maxillofacial surgeon’s office, where they complain of progressively worsening bite or facial esthetics (retruding chin, for example). They may or may not have concurrent TMJ symptoms (reproducible sharp intraarticular ear pain, limited mouth opening, and so on), so this should not be used to distinguish ICR from other TMJ diagnoses. There are certain general clinical features of ICR (e.g., retrognathia; a high mandibular plane angle; a short lower facial third, with or without anterior open bite, often involving bilateral TMJs), but some of these may overlap with other confounders, so it is imperative that the surgeon completes the workup starting with a detailed documentation of the patient’s chief complaint, paying particularly close attention to the progressivity of the disease process to arrive at the correct diagnosis.
HPI
The patient initially presented several years ago with a progressively receding chin and a worsening bite, seeking orthognathic surgery to correct her facial deformity and skeletal malocclusion. Two different imaging modalities revealed severely resorbed condyles on both sides. At that time, she had no associated TMJ symptoms. Potential surgical options were discussed, but the patient decided to postpone her surgery. She then returned 3 years later with a new bilateral myofascial pain and a slightly worsened overjet, desiring to proceed with previously discussed surgery. She denied any trauma to her face or the jaws, previous orthodontic therapy, or any other jaw surgeries.
PMHX/PDHX/medications/allergies/SH/FH
The patient was taking an oral contraceptive (norethisterone) at the time of initial presentation 3 years ago but has since discontinued its use. The remainder of her past histories is noncontributory.
It is important that the surgeon takes a systematic approach to history taking when they suspect ICR because many local factors (degenerative joint disease, particularly juvenile idiopathic arthritis, infections leading to reactive arthritis, direct trauma, prior orthognathic surgery or orthodontic therapy), as well as systemic conditions (rheumatoid arthritis, scleroderma, systemic lupus erythematosus, psoriatic arthritis, steroid use) can confound the final diagnosis. A thorough documentation of the past histories, including medical, surgical, social, and family history; review of current medications; and allergies is used to help rule out the potential confounders (especially the TMJ-only juvenile idiopathic arthritis because this condition clinically appears identical to ICR). Because the other diagnoses have been ruled out and no other explanation can be given for a patient’s condylar resorption (either unilateral or bilateral), ICR can be considered as a possibility.
Examination
General. The patient is a well-developed and well-nourished female in no apparent distress.
Maxillofacial
The patient has normal mouth opening of 52 mm with normal lateral excursions and protrusion. There is 3 to 4 mm of anterior open bite with molars and canines in a class II relationship bilaterally. A discrepancy of 2 to 3 mm was noted between centric relation (CR) and centric occlusion (CO). Overjet is 9 mm, which has slightly worsened from 7 mm from 3 years prior. She does not have any TMJ clicks or pops, nor any reproducible sharp intraarticular ear pain, but she does have some dull, throbbing pain to the bilateral masseter and temporalis muscles upon palpation. The rest of her clinical examination is unremarkable.
On clinical examination, the following pattern may be noted in patients suspected to have ICR, including those with a class II skeletal malocclusion either with or without an anterior open bite, retrognathia, a short ramus height with increased mandibular plane angle, and positive overjet, all of which can either be progressive or be in “remission.” Although not absolute, a good number of these patients tend to be females who are 15 to 35 years of age (several reported female-to-male ratios of 9:1, 8:1, and 13:1). Additionally, it is important to look for and record the CR-CO shift in these patients because surgical planning must be based on the CR position.
Imaging
The most frequently used imaging modality by oral and maxillofacial surgeons when evaluating a patient for ICR is the orthopantomogram followed by computed tomography (CT) or cone-beam CT (CBCT). Other modalities include magnetic resonance imaging, two-dimensional radiography (lateral cephalometric radiograph, posteroanterior cephalometric radiograph), and nuclear imaging. Each has its own set of pros and cons and provides the surgeon with different information, which together are used to follow disease progression and help assess resorptive activity. The orthopantomogram and CT or CBCT provide information on the structural morphology of the condyle. (The hallmark sign of ICR is shrinkage in all three planes of dimension, resulting in an appearance of a miniaturized condyle.) Both can be taken serially over a period of time to help track disease progression. However, the disadvantage is that time is required to assess the progressivity, which is not always accepted by the patient. Nuclear imaging using technetium-99m can provide immediate information on resorptive activity, but it only functions as a timestamp and provides no information on disease stability and thus should not be used to determine timing of surgical intervention (i.e., a negative result does not guarantee that the resorptive process has stopped). Of note, the only guarantee that the resorptive process has ceased is if the condylar resorption reaches the sigmoid notch. Additionally, nuclear imaging is not specific to ICR (i.e., can be positive in other conditions such as degenerative joint disease).
For the current patient, the orthopantomogram and CBCT showed severe bilateral condylar resorption, which was worse on the left than the the right side. In addition, the lateral cephalometric radiograph demonstrated an anterior open bite with a steep mandibular plane angle.
Labs
There are no routine laboratory tests specific or sensitive to detecting ICR. However, one may consider the following studies as part of a comprehensive workup to rule out other systemic and inflammatory conditions:
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Antinuclear antibody
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Cyclic citrullinated peptide (CCP)
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Human leukocyte antigen
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Rheumatoid factor
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Vitamin D
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C-reactive protein (CRP)
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Erythrocyte sedimentation rate (ESR)
Assessment
Idiopathic condylar resorption.
The diagnosis should be based on patient history, clinical evaluation, and imaging findings. A “typical” ICR patient may be a female between 15 and 35 years of age with a high mandibular plane angle, class II skeletal malocclusion, and a retruded chin who say their chin position or bite has been worsening over the years with no other explanation for the observed condylar resorption ( Fig. 69.1 ). Important features of ICR in addition to the aforementioned clinical appearance include the characteristic three-dimensional morphology of the resorbed condyle (“miniaturized condyle”) and a CR–CO shift ( Fig. 69.2 ).
