October 8, 2021
by David J. Psutka, D.D.S., F.R.C.D.(C)
I read with great interest the response letter written by Dr. Mark Antosz to my editorial published in Oral Health in the June issue of this year. Dr. Antosz’s letter appeared in the August issue.
The purpose of my editorial was to comment on the effect the COVID-19 pandemic has had on oral and maxillofacial surgeons and their patients. I did comment on the specific effects seen in patients with existing TMDs. I also commented on the effects of the pandemic on our hospital system and, in particular, those awaiting elective surgery. This was not an article specifically about TMJ surgery nor was there a suggestion that TMJ surgery was the only treatment option available to patients. Indeed, my editorial discussed the spectrum of surgical and non-surgical therapies.
A classification system for temporomandibular disorders is important. It helps establish what treatment algorithms are appropriate for the patient. It also underscores the diverse nature of pathology that can affect the TMJ apparatus. Structural TMDs (ankylosis, condylar resorption, trauma, tumours) nearly always need surgery, usually as the first treatment. Functional TMDs (internal derangements, osteoarthritis, masticatory myalgia and, to a lesser extent, recurrent dislocation) most often are successfully managed non-surgically. However, surgery can be useful in accelerating the timeframe to pain relief. A small percentage of patients do not respond to non-surgical treatments and ultimately benefit from surgery. The ability to recommend any treatment (surgical or non-surgical) depends on a good understanding of the pathobiological process that causes the pain.
The concept that TMD is “first and foremost a problem with the occlusion” is an old treatment concept. The author states, “It’s muscles trying to protect teeth, little more than that.” This is a simplified version of the Vicious Cycle Theory of TMD pain. Numerous extensive occlusal therapies were launched under the flag of “fixing” the cause of TMJ muscle or joint pain in the ’70s and ’80s. This applied to orthodontic treatments as well as prosthodontics and orthognathic surgery.
The Vicious Cycle Theory has been disproven by EMG studies and repeatedly refuted in our scientific literature (Lund et al., 1991, 1993; Lund and Stohler, 1994; Stohler and Zhang, 1996; Majewski et al., 1984; Stenson et al., 1998). The Pain Adaptive Model proposed by Lund et al. in 1991 is currently a favoured theory for explaining TMD related pain.
Speaking specifically of TMJ arthralgia, TMJ degeneration is the result of an imbalance between catabolic and anabolic processes that control articular surface health and remodelling. Fibrocartilage and bony degeneration result from extracellular matrix breakdown. This is a biochemical process that results from proteases that are released from damaged chondrocytes and synovial cells. The damage can be from macrotraumatic or microtraumatic events (microtraumatic commonly being parafunction).
This current understanding is reflected in the Royal College of Dental Surgeons of Ontario Guidelines for the Treatment of TMDs. I understand the RCDSO is currently looking at making this document a standard of care as opposed to a guideline of care paper. The last paragraph of the current guideline states:
“Equally, there is little evidence in support of the suggestion that surgical or orthodontic correction of a malocclusion will predictively alter the course of an intraarticular disorder. Patients with a significant TMD, a concurrent severe malocclusion (in particular an open bite deformity or a severe Class II malocclusion with a deep overbite) and where the malocclusion may be a predisposing exacerbating factor in their disorder, might benefit by surgical (orthognathic surgery) or orthodontic correction of the malocclusion as part of an overall management strategy. Correction of a malocclusion is best considered on its own merits and should not be considered as the primary treatment with respect to management of the TMD.”
In other words, treat the TMD first (usually with conservative measures like splints, medication, and physiotherapy) then give careful consideration to correcting the malocclusion.
With a good understanding of the pathobiology of intraarticular degeneration, the treatments that are undertaken surgically make biological sense. The lavage of arthrocentesis and arthroscopic surgery wash out the painful and degeneration inducing cytokines. Arthroscopic manoeuvres like adhesion release and the ablation of fibrillated fibrocartilage mobilize locked discs and create smoother articular surfaces. The injection of platelet rich growth factors introduces ortho-biological treatments that can reverse degeneration and promote healing.
There is mounting evidence that in some types of cases, there are better outcomes when the surgery is performed earlier rather than later in the disease process. The dental scientific literature has numerous publications that look at the efficacy of various treatments for TMD, including surgery. There are numerous randomized control trials and meta-analyses that have been published over the decades. An excellent summary of some of these studies and of the role of surgery in managing TMDs is currently an article in press with The Journal of Oral Maxillofacial Surgery, Oral Medicine, and Oral Pathology. The article is entitled “The Current Role of Arthrocentesis, Arthroscopy, and Open Surgery for Temporomandibular Joint Internal Derangement with Inflammatory/Degenerative Disease:/Pitfalls and Perils.” This was written by Professor K. Murakami. I highly recommend this article for those interested.
There is a lot to be said for experience in clinical practice. However, anecdotal evidence is the least reliable of all the forms of scientific evidence. This should be kept to coffee shops and cocktail parties. For readers interested in a scientific understanding of the pathobiology of TMDs (and the rationale for various treatment algorithms) I recommend the following reference textbook. “Temporomandibular Disorders. An Evidence-Based Approach to Diagnosis and Treatment.” Edited by Daniel Laskin, Charles Green, and William Hylander. 2006, Quintessance Publishing Company Incorporated.
In the same letter, I was dismayed to see Dr. Antosz cast aspersions on oral and maxillofacial surgeons in general by commenting on their general alleged lack of knowledge regarding occlusion. I am sure Dr. Antosz has relied on his local OMFs skill and knowledge when he has referred his patients for orthognathic surgery. These cases of course are the most challenging occlusal problems.
I reiterate the opinion written in the last line of my June editorial. “The ethical and caring nature of our profession combined with ever improving, evidence-based, scientifically-sound management strategies will help us all in moving past the pandemic.”