Application of the Surgery-First Approach to Facial Asymmetry

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© Springer Nature Singapore Pte Ltd. 2021

J.-W. Choi, J. Y. LeeThe Surgery-First Orthognathic Approachdoi.org/10.1007/978-981-15-7541-9_13

13. Clinical Application of the Surgery-First Approach to Facial Asymmetry

Jong-Woo Choi1   and Jang Yeol Lee2  
(1)

Department of Plastic Surgery, Asan Medical Center, Seoul, Korea (Republic of)
(2)

SmileAgain Orthodontic Center, Seoul, Korea (Republic of)
 
 
Jong-Woo Choi (Corresponding author)
 
Jang Yeol Lee
Keywords

Facial asymmetrySFATraditional orthognathic surgeryHorizontal facial asymmetryVertical facial asymmetryClassification

13.1 Facial Asymmetry Classification

Traditionally, facial asymmetry has been classified in many ways. Among these, the following categorization is the most feasible. According to Fonseca and Turvey’s facial asymmetry classification, facial asymmetry can be categorized into four types (Fig. 13.1) [1, 2].

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Fig. 13.1

Turvey’s classification of facial asymmetry

However, in my opinion, one more category is needed: craniofacial asymmetry originating from asymmetry of the cranial base, which would be the most difficult facial asymmetry to manage. Therefore, I suggest this modified classification of facial asymmetry.

  1. 1.

    Pseudoasymmetry.

     
  2. 2.

    Normal developmental facial asymmetry.

     
  3. 3.

    Unilateral overdevelopment.

     
  4. 4.

    Unilateral underdevelopment or degeneration.

     
  5. 5.

    Craniobasal asymmetry.

     

13.1.1 Pseudo Facial Asymmetry (Fig. 13.2)

Pseudo facial asymmetry is not true facial asymmetry, despite the asymmetric positioning of the mandible. Occlusal interference, habitual posturing, condylar dislocation, or dystonia are potential causes. As a result, the condyle is displaced forward relative to centric relation (CR) in the fossa. Conversely, true asymmetry involves facial asymmetry that exists while the condyle is seated in its original temporomandibular joint (TMJ) CR. Therefore, in this situation, the asymmetry would not be corrected although the condyle was situated in a gentle superoposterior position (Figs. 13.2, 13.3).

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Fig. 13.2

Pseudoasymmetry is not true facial asymmetry, despite the mandible being asymmetrically positioned. Occlusal interference, habitual posturing, condylar dislocation, or dystonia are potential causes

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Fig. 13.3

An example of pseudoasymmetry where the condyle is displaced relative to the centric relation in the fossa

13.1.2 Developmental Facial Asymmetry (Fig. 13.4)

Developmental asymmetry is the non-pathologic, non-syndromic development of facial asymmetry. Genetics, intrauterine molding, or natural growth variances may cause developmental facial asymmetry. Usually, the facial asymmetry is present at birth but is not identified until later. To be categorized as developmental facial asymmetry, TMJ-related pathology or symptoms should be absent. Both condyles may be approximately equal in size and shape and most patients demonstrate similar condylar proportions during growth.

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Fig. 13.4

Developmental facial asymmetry. Developmental asymmetry is the non-pathologic, non-syndromic development of facial asymmetry

13.1.3 Overdevelopmental Facial Asymmetry (Figs. 13.5, 13.6)

Unilateral mandibular hyperplasia is a typical example of overdevelopmental facial asymmetry. The ipsilateral mandibular ramus, body, and parasymphysis, including the condyle, are enlarged while the contralateral mandible appears normal. Specifically, unilateral condyle hyperplasia is a good example of overdevelopmental facial asymmetry.

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Fig. 13.5

Overdevelopmental facial asymmetry. Unilateral mandibular hyperplasia is a typical example of overdevelopmental facial asymmetry

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Fig. 13.6

Unilateral mandibular hyperplasia corrected using orthognathic surgery

13.1.4 Underdevelopmental Facial Asymmetry (Figs. 13.7, 13.8)

The etiologies of underdevelopmental facial asymmetry are diverse. This type of asymmetry can be categorized as congenital, acquired facial asymmetry, adolescent internal condylar resorption, or as a connective tissue disorder.

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Fig. 13.7

Underdevelopmental facial asymmetry

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Fig. 13.8

Underdevelopmental facial asymmetry corrected using yaw and pitch movements of the maxillomandibular complex during surgery-first orthognathic surgery

Congenital underdevelopmental facial asymmetry includes unilateral cleft lip and palate, hemifacial microsomia, and Treacher Collins syndrome. Acquired underdevelopmental facial asymmetry may result from trauma, infection, or ankylosis. Idiopathic condyle resorption (ICR) presents unilaterally and can also cause underdevelopmental facial asymmetry.

13.1.5 Craniofacial Asymmetry (Fig. 13.9)

Mar 5, 2021 | Posted by in Orthodontics | Comments Off on Application of the Surgery-First Approach to Facial Asymmetry
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