Prof. Daniele Manfredini

This lecture will provide an overview of the orthodontist’s role in the practice of temporomandibular disorders (TMDs). Decades of clinical research have provided growing scientific evidence on the absence of relationship between features of dental occlusion or condylar position and TMDs. They also shed light on the need to focus on neurological and psychological issues for a proper management of patients with temporomandibular joint (TMJ) and jaw muscle pain. Whilst this evidence is fully embraced by dentists with expertise in the orofacial pain field, it is still hard to swallow by some communities of orthodontists. Claims that there is purported “clinical evidence” in support of mandibular repositioning and orthodontic finalization, on anecdotic basis and inductive reasoning, is the best argument to confute any scientific reasoning. Invasive treatments in the form of irreversible occlusal changes and years-long treatment are thus still proposed, against any recommendations by the expert academies. Some arguments to discourage orthodontic treatment to treat TMDs are simply based on oral physiology. For instance, teeth almost never really touch in maximum intercuspation; movement guidance is important for an articulator, but never performed in real life; features of the interrace relationship are just a static frame; condylar position is asymmetric by definition; the condyle-fossa or condyle-disc relationship cannot be “corrected” only on one side, and this is bizarre if one considers that most patients have unilateral symptoms. Thus, any occlusally-oriented etiological theory for TMDs needs for all sort of exceptions against physiology to be considered “true”. Consequently, it not a surprise that the literature, which is indeed based on patients (i.e., clinical evidence!), dismantles such theories. For instance, how to explain TMD pain in patients with good occlusion? And what about the absence of symptoms in patients with bad-looking occlusion? And the many patients with asymptomatic osteoarthrosis? Only anecdotes can help an occlusal practitioner finding an explanation in front of these patients.In short, orthodontics can be considered neutral, at best, for the TMJs. It cannot cure TMDs, but it is also unlikely that it may cause TMJ symptoms. Knowledge on the epidemiology of TMJ sounds is fundamental for understanding the latter statement.Within these premises, bruxism in the form of isometric bracing as an expression of vigilance and emotional tension has clearly emerged as the most important clinical factor in the pathophysiology of TMDs. Orthodontics, either with traditional brackets or aligners, may increase the muscle work in some individuals, explaining the potential onset of mild symptoms in course of orthodontic treatment that have nothing to do with the biomechanics of treatment itself.So, what should a practitioner do?  The answer is that an orthodontist should realize that TMD symptoms are mainly due to an emotional overload, which leads to muscle tension and, via host response, to the onset of signs and symptoms. The orthodontist looking outside from the TMD patient’s mouth will easily see an individual with emotional distress, and without any occlusal or TMJ positional clue to explain symptoms, if compared with asymptomatic individuals. Depending on the symptoms, management strategies ranging from very simple behavioral advices for the control of awake bruxism to complex multimodal strategies for chronic orofacial pain are the required approaches. Within the concept of overload, an oral appliance is just a crutch, not the cure or a diagnostic device. Thinking of it makes everything immediately fit with all the clinical knowledge that has been sustained by generations of orofacial pain practitioners. 
Learning objectivesTo gain an update on current evidence on temporomandibular disordersTo understand that orthodontics is neutral with respect to temporomandibular disordersTo provide ethical messages about the need to avoid occlusal overtreatments for TMD management