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Smile Arc and TMJ Health

Smile Arc  and TMJ health

by Dr. Michel Champagne, BA, DMD, MAGD, IBO, CDE 

Today the smile arc is a common concept in orthodontics. The goal of attaining an aesthetic smile is part of most every orthodontic treatment and is often a request of the patients. Maybe doctor Google has something to do with it. The question still stands, what are the limits of a nice smile arc and also is there a relationship between an extreme smile arc and TMJ health? We will probably all agree that orthodontics had to move from the straight smile arc concept of the 80’s, that was mainly attained by upper incisor intrusion. What may happen if a clinician pushes the enveloppe too far? I am not pretending that I have a good answer to the question but I sure have some interrogations:

  1. If the upper incisors are elongated to comply with the smile arc, what becomes of the overbite? We will probably need to extrude the lower posterior teeth and/or intrude the lower incisors.
  2. With the contemporary concept of the smile arc, if the overbite is increased, will it restrain the  movement envelope of the mandible both in protrusion  and laterality? We all know, I hope, if the envelope of movement is not free of any interference, greater stress will be inflicted to the TMJ’s and the patient occlusal tolerance will be sollicitated. We may see premature contacts both in centric occlusion and lateral movements. Such a restriction inside the Posselt triangle can have a negative effect, overcharging the TMJ’s, causing premature occlusal wear and reducing the stability of the case.

A clinician who is aware of the implications of a contemporary smile arc can compensate taking into consideration all of the factors. Knowledge is the base of everything.  You cannot see what you do not know and even less take it in consideration. We have to create great smiles and also  protect the function.

Just a thought.

Keep safe in these difficult times.

                           

Smile arc concept and  bracket position .

 

                                                   

Posselt  Triangle                                                           The dynamic movements must not interfere with the envelope limits