1. What is condylar resorption?
Healthy condyles are very important to facial form and function (Figure 1). Within the temporomandibular joints (TMJs), condyles act as a biological lever allowing the lower jaw to pivot for day-to-day functions that can easily be taken for granted, such as talking, eating, and breathing. When condylar resorption occurs, condylar head degeneration results in height loss of the condyle and, thus, shortening of the back part of the face (posterior).
Figure 1. Anatomically normal jaws.
Proportional condyle and ramus height result in a normally angled mandibular plane (shown in red). Normal horizontal and vertical maxilla position.
This degeneration also causes bite changes, such as progressively worsening lower jaw recession that results in the formation of an overbite/open bite (Figure 2). The occurrence of these bite changes during puberty can also alter the trajectory of upper jaw growth, resulting in more vertical growth and less forward growth (Figure 3) [1]. Condyle degeneration can cause joint pain in some, and is also associated with decreased airway size, postural issues (i.e. forward head posture, cervical kyphosis, etc.), a limited mouth opening, dental damage (particularly to the back molars), and muscular pain in the head and neck.
Figure 2. Condylar resorption resulting in a class 2 bite with a large anterior open bite.
A) Shortening of the condyle causes clockwise rotation of the mandible, a steeper mandibular plane, and development of an anterior open bite.
B) Overlay of anatomically normal jaws (blue) and the condylar resorption jaw shown in panel A (pink). Overlapping regions appear purple.
Figure 3. Condylar resorption-associated anterior open bites can be masked by excessive vertical maxillary growth during puberty.
A) Shortening of the condyle causes mandibular recession and steepens the mandibular plane. Mandibular recession prevents the lower jaw from providing pressure cues needed to guide forward maxillary growth, resulting in excess vertical growth.
B) Overlay of anatomically normal jaws (blue) and the condylar resorption jaw shown in panel A (orange). Overlapping regions appear brown.
2. Do we know what causes condylar resorption?
There is still a lot we don’t know about condylar resorption; in fact, you will commonly see it referred to as idiopathic condylar resorption (ICR). Idiopathic is defined as relating to or denoting any disease or condition which arises spontaneously or for which the cause is unknown.
Here are some factors that are known to be associated with activation or reactivation of condylar resorption:
▸female-associated hormonal profile (female-to-male ratio between 9:1 [2] and 16:1 [3])
⇢ disease activity flare-ups with puberty, pregnancy, or other hormonal changes
⇢ males have generally been observed to present with low testosterone and autoimmunity, but studies are needed to further validate and explore this
▸autoimmune disorders, such as rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, and others [2]
▸connective tissue disorders, such as Ehlers-Danlos syndrome (EDS) and others [5]
▸treatments that impact TMJ loading (the force applied to the articular surfaces of the jaw joint.) [1]
⇢ orthodontics
⇢ jaw surgeries
⇢ dental orthotics (i.e. splints, appliances, etc.)
▸history of facial trauma [1]
▸other unknown triggers
Even with what we do know about developing condylar resorption, the specific mechanisms, such as those driving condylar resorption in one patient undergoing orthodontic treatment and not another, are still awaiting in-depth characterization.
3. How is condylar resorption diagnosed?
Finding a medical professional to diagnose and appropriately treat condylar resorption can be a significant obstacle for many patients, with some patients being undiagnosed for decades. Dentists, orthodontists, and jaw surgeons who do not specialize in joint diseases and joint surgeries may not recognize the signs of condylar resorption and may respond with treatment strategies that exacerbate disease.
Consulting with surgeons that specialize in both jaw bones and jaw joints may help undiagnosed-but-symptomatic patients avoid some of the initial confusion in navigating diagnosis and treatment. When getting screened for condylar resorption, your physician will likely order scans of your TMJs. Some cases may only need a cone beam computed tomography (CBCT) scan to visualize key features of condylar resorption and arrive at a diagnosis. For other patients, additional scans, sometimes taken over time, may be necessary, such as a CT, MRI, tech99, and others.
For help finding surgeons qualified to assess, diagnose, and treat condylar resorption, please see our Resources page.
Patient being prepared for a CBCT scan.
4. What are the treatment options for those with condylar resorption?
There are a variety of treatment options that may be presented to condylar resorption patients. It is important for every patient and their physician to conduct a basic risk-reward analysis when determining what their treatment plan will look like. Below is a summary of the pros and cons of common conservative and surgical treatment options:
Conservative treatment options:
▸watch-and-wait approach
⇢ pros: this can be a low cost option for patients not experiencing any significant functional issues with their airway and/or bite, or pain related to the TMJs or muscular dysfunction of the head and/or neck.
⇢ cons: disease progression may continue and become symptomatic.
▸orthodontics
⇢ pros: this can be a low-to-moderate cost option for patients looking to straighten their teeth and improve their bite.
⇢ cons: orthodontic relapse associated with an open bite is common [6] and orthodontics may aggravate disease. Orthodontic movements attempting to close large open bites and/or overbites using proclination, or overjetting, may cause bone loss and gum recession [7].
▸splints, orthotics, or other appliances
⇢ pros: this can be a low-to-moderate cost option for patients that may alleviate pain, protect teeth, and provide mild improvements to symptoms of sleep apnea [1, 8].
⇢ cons: splint therapies, particularly long-term, can cause anterior open bites to develop [9] and may accelerate disease. Expansion appliances have the same concerns as orthodontics in terms of proclination, bone loss, and gum loss.
Surgical treatment options:
▸arthroscopic surgery (i.e. lavage, aspiration, debridement, etc.)
⇢ pros: this can be a low-to-moderate cost option for patients experiencing joint pain and a limited opening [10].
⇢ cons: arthroscopic surgeries cannot predictably stabilize the condyles and repeated joint surgeries have been shown to be associated with worsened TMJ replacement outcomes later [11].
▸jaw surgery
⇢ pros: this can be a moderate-to-high cost option for patients in a long period of disease inactivity. The bite and airway are significantly improved immediately following surgery.
⇢ cons: the occlusal relapse risk for patients with a history condylar resorption is higher than patients with healthy joints. The presence of a relapse history (surgical) has been shown to result in high downstream relapse rates of 46-100% [1]. This finding may also indicate a need for caution in patients who have experienced non-surgical relapse or general disease activity. Patients that experience multiple failed jaw surgeries may have worsened outcomes relating to nerve damage, scar tissue, facial pain, and other complications [12].
▸TMJ replacement
⇢ pros: this can be a moderate-to-high cost option that allows patients to specifically address the diseased joints. Relapse due to condyle breakdown cannot occur following TMJ replacement.
⇢ cons: under current medical science, receiving a joint replacement is a permanent choice. Diseased condyles are excised (condylectomy) as part of joint replacement, so mandibular function is dependent on the prosthetic following surgery. While the longevity of TMJ prosthetics is still being tracked (the longest study to date shows many patients doing well 20-25 years post-op [13]), patients should have a later re-replacement on their radar. Patients should be appropriately screened for metal allergies before ordering their joints. If necessary, all-titanium prosthetics can be obtained through the FDA’s compassionate use/expanded access program. Other post-op concerns include infection, dislocation, and heterotrophic bone growth [14, 15].
5. What are the long-term consequences of condylar resorption?
In an ideal world, we would be able to predictably stop repeated episodes of condylar resorption. However, this is not currently possible, leaving many questions regarding long-term disease progression difficult to answer. While some condylar resorption patients may have significant symptoms associated with less significant resorption, others may have only minor symptoms with significant resorption. It is critical for every condylar resorption patient to thoroughly communicate their symptoms and concerns with their treating physician.
Below are some aspects of health that condylar resorption patients should be aware of and monitoring:
▸ Airway health
Some of the most concerning implications of long-term condylar resorption are the effects of chronic airway restriction and sleep apnea. Side effects of sleep apnea can range from minor discomfort, such as day-time sleepiness, to major health events, including heart attack and stroke [14]. For additional reading, check out the related blog post: Condylar Resorption, Posture, and Your Airway.
▸Spinal health
Forward head posture has long been thought to develop in people with small airways to maintain airway adequacy [15], however this posturing has a variety of consequences for spinal health. In addition to encouraging the development of military neck/cervical kyphosis [16], chronic forward head posture can contribute to pain and muscle tension in the head, neck, and spine.
▸Dental health
The presence of an anterior open bite results in dental occlusion only occurring on the back teeth (molars). Over time, the weight of the whole bite being carried by just the molars can cause these teeth to breakdown. This breakdown leaves teeth increasingly vulnerable to infection and the development of (sometimes complex) dental pain.
▸Nerve health
Chronic inflammation and trauma to the teeth and joints can result in the development of neuropathic pain. Neuropathic pain can sometimes be difficult to treat and cause stress and anxiety in a patient’s day-to-day life [17]. Any changes to a patient’s pain profile should be reported to their treating physician.
▸Gastrointestinal health
Frequent use of certain medications to control pain and inflammation, such as NSAIDs (ibuprofen, naproxen, etc.), can damage the stomach lining. If you’re experiencing stomach discomfort, it is important to talk to your primary care physician about preventing the development of ulcers and other GI-related issues. Eating when taking medication, as well as using acid reducers, such as proton pump inhibiters and histamine-2 blockers, can help reduce stomach-related discomfort and injury [18, 19].
▸Mental and Emotional health
Symptomatic condylar resorption is a very stressful experience. Facial changes, pain, difficulty eating, disrupted sleep, feelings of isolation, and other experiences can easily take a toll on mental and emotional well-being. Never hesitate to reach out to a mental health professional, ask for accommodations when needed at work or school, and prioritize your needs.