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3 Reasons Muscle Assessment and a Structured Exercise Program is Necessary for Jaw Surgery

Updated: Aug 2, 2021

Individuals with severe dentofacial deformities (DFD), such as Type II malocclusion (overjet, overbite) and Type III underbite, who are submitted to orthodontic treatment and orthognathic surgery (OGS) “Jaw Surgery” usually are seeking improvements in facial esthetics and function of the teeth, jaws, and associated soft tissues. It has been reported that 85% of individuals who wanted jaw surgery were for oral function and 71% wanted Jaw Surgery for dental appearance. The three reasons why these individuals sought Jaw Surgery were to improve biting or chewing (oral function), dental appearance, facial appearance, and to prevent future dental problems.

In a case study, 16.7% of individuals were dissatisfied with the overall jaw surgery results due to the persistence of the Anterior open bite, horizontal relapse, and sensory impairment.

These reasons for individuals to pursue Jaw Surgery has led me to give you the top 3 reasons muscles assessment and a structured exercise program is necessary before and after Jaw surgery.

  1. Jaw Muscle Function - Reduce mouth opening

  2. Symmetry & Facial Gestures

  3. Chewing & Swallowing Function

1. Jaw Muscle Function

The most common impacted muscle function is reduced mouth opening or Trismus. Trismus is an uncontrolled inability to open the mouth or jaw. Trismus interferes with many daily activities such as chewing, swallowing, talking, kissing, brushing teeth, breathing, having a breathing tube placed, and even having dental or orthodontic treatment. This has been the case for several patients where orthodontic treatment after surgery had to be postponed because the muscles of reduced mouth opening were able to measure and install the brackets.

Trismus can happen anytime during, right after, or even years after your treatment. 3 ways it could happen are:

  1. If you have a tumor that involves the bones, muscles, and nerves that open your mouth.

  2. After surgery on your head, neck, and jaw.

  3. After radiation therapy to your head and neck.

Trismus tends to improve slowly around 3-12 weeks post-surgery; however, early treatment is the best way to prevent more severe problems and decrease the risk of delaying orthodontic treatment post jaw surgery. Some of the severe problems you can experience from Trismus are increased jaw pain, inability to open mouth 35mm to 55 mm, spasms or tight sensation when attempting to open the mouth, difficulty chewing, difficulty talking, difficulty breathing, and difficulty brushing and flossing your teeth.

Once trismus develops, it’s very hard to treat. That’s why it’s important to prevent trismus and treat it as early as possible. The earlier you start treatment for trismus, the easier it will be to help your jaw work better. If you notice any tightening in your jaw, ask your healthcare provider to refer you to an Oral Facial Myofunctional Therapist who has a background in speech pathology. Speech pathologists are highly trained in the area of chewing and all phases of swallowing, speech, and speech pathologist with a specialization in Orofacial Myofunctional Therapy have a deeper understanding of the head, neck, and jaw muscles. You can contact TASL Speech Therapy Consultants for a consultation.

2. Facial Asymmetry and Expressions

Facial expressions are the most common means of communication with 55% of the daily social interactions being nonverbal and dependent on facial expressions. Patients should be warned of restrictions in facial expressions during the first 6 months after surgery. Facial expressions are dependent on the movement of facial muscles and their relation to underlying bones. Facial soft tissue adheres to the bone this is directly influenced by surgical positional changes of the hard tissue in all directions. The lower and upper lips, however, are not connected directly to the bone, and their positional changes are indirectly related to postoperative changes of adjacent soft tissue that is directly adhered to the bone, except for proportional changes in the anterior-posterior direction according to the positional changes of the incisor. This is why the facial muscles should be assessed before jaw surgery to determine the position and function of the soft tissue. Collaboration between a Myofunctional Therapist and oral surgeon is critical to understand how the soft tissue functions before and after surgery.

Post-surgical stability is dependent on muscle balance and that relapse is more likely if the functional impairments of facial expressions persist after orthognathic surgery. Facial expressions have an impact on the diagnosis of facial soft tissue impairments, planning of the surgical correction, and assessment of surgical outcomes. Therefore, it is important for the evaluation of the dynamics of the soft tissue by a Myofunctional Therapist before the surgical planning for the correction of skeletal deformities. It also is valuable to evaluate the changes in the pattern and magnitude after orthognathic surgery, which can affect the stability of the achieved results.

3. Chewing and Swallowing

Even after surgical orthodontic treatment, the level of masticatory function in patients with jaw deformities is still lower than that of healthy subjects. Chewing is an important function of the stomatognathic system; the ideal pattern is bilaterally alternated, with sealed lips and jaw rotation movements with no movement of the head or other body parts, enabling the distribution of masticatory forces with functional and muscular balance, but depending on factors of occlusal balance. Chewing can be altered in individuals with dental-facial deformities. In Class III malocclusion the vertical mandibular movements are predominant, with the utilization of the tongue to crush the food against the palate and little or no action of the buccinator muscles. In Class II malocclusion, usually, the lack of lip sealing can be observed in the presence of a long face, determining little use of orbicularis oris muscles and buccinators, accompanied by less movement of tongue lateralization. Oral Myofunctional Therapy brought favorable physiological changes in the chewing and swallowing cycles after surgery.

An individual undergoing jaw surgery must consider an interdisciplinary approach before and after surgery. This approach must include the assessment of the soft tissue or facial muscles and a structured exercise program. It is possible to intercept and re-educate all the muscle functions that are not compliant with the structural changes and to eliminate a tendency to relapse. Contact TASL Speech Therapy Consultation to begin your process.


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