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NEWS & EVENTS

Mandibular Growth and Disc displacement of TMJ

Lateral Deviated Mandible

Temporomandibular disorders with mandibular deviation and facial asymmetry in adolescence

Bite and Temporomandibular Disorder (TMD)

Condylotomy

Orthognathic Surgery and Temporomandibular Joint Disorder

Bite and Temporomandibular Disorder (TMD)

Large-scale researches published by well-known scholars Pullingwe et al. has indicated that dental malocclusion was not the major cause of TMD (Pullinger AG,1991,1993,2000,2001). However malocclusion has been connected with TMD for a long time. It should be noted that TMD couldn’t be fully treated with only orthodontics or occlusal adjustment. Multifactor analysis of Seligman showed that occlusal factor accounted for 10-20% of TMD (Seligman DA,1991). Most people have good joint adaptability to cope with malocclusion and maintain joint stability. However a few occlusal factors can easily cause joint instability, e.g. anterior open bite, overjet greater than 6mm, CR-CO greater than 2mm, unilateral crossbite and posterior teeth missing more than 5.
 

Orthodontics and TMD

It is generally believed that orthodontics improving malocclusion "should be" beneficial to the stability of TMJ. Some scholars hold the opposite view that orthodontics improving malocclusion "might" exacerbate TMD. Based on literature review, we drew the conclusion that orthodontic treatment neither cause the signs of TMD nor be helpful to the treatment of TMD (Sadowsky C,1984. Hirata RH,1992)。


Jaw Deformity, Orthognathic Surgery and TMD

Jaw deformity is usually coupled with TMD.
While facing patients with jaw deformity, Clinicians should figure out the symptoms are simple abnormalities in bone development (i.e. joint is still healthy) or caused from joint disorders affecting bone development.
 

Over the past few decades, the correction and surgical treatments for jaw deformity and malocclusion have been repeatedly discussed. From 3 long-term follow-up clinical studies with higher reliability (Onizawa JP, 1995. Panula K, 2000. Dervis E, 2002), we drew the following conclusions:

    
1. No significant difference was found in the percentage of patients who showed signs of TMD between the operative and non-operative patients with dentofacial deformity.
    
2. The signs of TMD were very likely to get improved after orthognathic surgery or orthodontic treatment.
    
3. Few patients showed deteriorating signs of TMD after surgery.
    
4. Both masticatory muscle tenderness and joint tenderness decreased after orthognathic surgery or orthodontic treatment.

For patients with TMD, before receiving the surgery, consideration should also be given to whether the surgery will lead to instability of TMJ or condylar resoprtion. Previous studies indicated that 1) female patients, 2) patients with retrognathia and high mandibular plane, and 3) surgical plan includes significant counterclockwise rotation of the jaw bones are the conditions that prone to post-operative joint instability or condylar resoprtion (Paulo MH,2012. Wolford LM,2002)。
 

The following 3 factors have influence on the TMD signs after orthognathic surgery:

    
1. Changes in the position of the masseters
    
2. Level of improvement in the relationship between mandibular condyle and articular disc
    
3. Psychological factor

It is essential to have a comprehensive examination and assessment of the TMJ before performing any facial bone surgery. Clinicians should consider the effect of orthognathic surgery on TMJ especially when severe TMD exist, e.g. idiopathic condylar resorption (ICR), condylar hyperplasia, articular ankylosis and disc displacement without reduction.