Post-Pandemic Dentistry: TMD Fact and Fiction

Editor's Note: Post-Pandemic Dentistry – Expert Perspectives

In September 2020, the American Dental Association (ADA) Health Policy Institute released findings from an impact poll highlighting an increase in certain oral health conditions since the onset of the COVID-19 pandemic. Doctors who participated in the ADA poll reported increases in bruxism (54.9%), chipped and cracked teeth (53.4%), temporomandibular disorder symptoms (53.4%) and caries (26.4%) among patients. In this series, Spear faculty explore what clinicians and practice teams must know to successfully treat these four conditions on the rise.

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The ADA recently released an article recently highlighting findings from a recent survey in which dentists reported a perceived rise in certain conditions since the onset of the COVID-19 pandemic¹. The assumption was that the added stress from the pandemic caused an increase in bruxism, chipped and cracked teeth and temporomandibular joint disorders.¹

The article reinforces the long-standing belief in dentistry that stress causes tooth grinding and TMJ disorders — and there is much more clinicians and teams must understand to effectively treat patients presenting with jaw pain amid the pandemic.

TMD fact and fiction

Structural breakdown in the masticatory system, whether at the tooth level or at the joint level, relates to two main factors. The first is the condition of the anatomic structures. At the tooth level, if a tooth has significant tooth structure missing or is excessive force is applied to the tooth, it is more likely to fracture.

At the joint level, if there is soft tissue (disk) and hard tissue (condyle) breakdown or if there are excessive loads applied to the joints, there is an increased likelihood patients will report symptoms.

The assumption that stress causes tooth grinding can be found in the dental literature as early as in the 1950s with Nadler writing, “the emotional tension expressed in such nervous habits as bruxism is built up by the inability to overcome or overlook the problems which include fear, rejection and inability to express rage, hate, or unexpressed libidinous desires.”²

This assumption relates to the belief that the primary source of pain in TMJ disorders is muscle pain. Raphael wrote in 2013, “the most prevalent subtype of TMD is myofascial TMD with pain/dysfunction in the masticatory muscles.”³ The assumption that stress causes grinding which causes muscle hyperactivity helps explain why the theory that tooth grinding causes joint problems was so pervasive.

Today, we understand that both tooth fracture and jaw joint issues relate to how forces are distributed in the masticatory system. Force distribution at the tooth level occurs best when there is simultaneous, and even-intensity contact on all the teeth during closure.⁴ Force distribution at the joint level occurs best when the disk is properly interposed between the condyle and the joint socket.⁵

In terms of the amount of load applied to the system, normal muscle activity can change if there is there is excessive contact on one tooth compared to simultaneousmdash;even intensity contact on all teeth. Additionally, the amount of force can increase based upon the input of the sympathetic nervous system.

There are four common clinical principles of sympathetic dysfunction⁶:

1. An increased sensitivity to pain.
2. Neurogenic inflammation which can manifest in swelling.
3. Sympathetically based muscle dystonia which may provide a more accurate understand of how and why bruxism occurs.
4. Emotional disturbance due to the influence of the sympathetic nerve on the limbic system. This may help explain the agitation or depression that sometime accompanies patients with occlusal issues.

Current research is concentrating on what causes a dysfunction in the sympathetic nervous system. Tissue changes from structural alterations in the TMJ can cause changes in the function of the sympathetic system as well as poor sleep quality and quantity. Understanding why certain patients may demonstrate increased level of muscle activity even when the occlusion is perfected can be explained through understanding the role of the sympathetic nervous system.

Moving beyond the myths

When a world-changing event like the COVID-19 pandemic occurs, it is common to associate disparate events to the pandemic. The reality is that bruxism and TMJ disorders were prevalent before the pandemic — and will be prevalent after the pandemic.

Occlusion and TMD continue to present unique challenges to our profession because we do not routinely assess the soft and hard tissue anatomy of the TMJ or the sleep quality/quantity of our patients.

If we can move our profession forward to assess joint anatomy and airway issues consistently, we will realize that these problems are not related to the COVID-19 pandemic, but rather are everyday issues in all our practices.

Jim McKee, D.D.S., is a member of Spear Resident Faculty.

References:

1. ADA News September 28, 2020 Versaci. MB.
2. Nadler, SC. Bruxism, a classification: critical review. J Am Dent Assoc. 1957;54(5):615–22.
3. Raphael K, Sirois D, Janal M, Wigren P, Dubrovsky B, et al. Sleep bruxism and myofascial temporomandibular disorders : A laboratory-based polysomnographic investigation. JADA 2012;143:1223-1231.
4. Dawson PE. New definition for relation occlusion to varying conditions of the TMJ. J Prosthet Dent 1995;74:619-627.
5. Piper, DMD MD, Mark. "Temporomandibular Joint Imaging." Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine. IGI Global, 2020. 582-697. Web. 24 Oct. 2019. doi:10.4018/978-1-5225-9254-9.ch009
6. Hooshmand, H. Hashmi M. Complex Regional Pain Syndrome(RSD Syndrome): Diagnosis and Therapy-A Review of 824 Patients. 1999; 9; 1-24.