Strategy for Class II Orthognathic Surgery: Orthodontic Perspective

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© Springer Nature Singapore Pte Ltd. 2021

J.-W. Choi, J. Y. LeeThe Surgery-First Orthognathic Approachhttps://doi.org/10.1007/978-981-15-7541-9_5

5. Treatment Strategy for Class II Orthognathic Surgery: Orthodontic Perspective

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)
Email: pschoi@amc.seoul.kr
 
Jang Yeol Lee
Email: jylee@saoc.co.kr
Keywords

Cl II surgeryRetrognathismGenioplastyASOCondylar resorptionSleep apneaOSAGummy smileOpen bite

5.1 Orthognathic Surgery for Patients with Class II Malocclusions

In Korea, the frequencies of Class II and Class III malocclusions are similar. However, significantly fewer patients with Class II malocclusions seek orthognathic surgery, compared with those with Class III malocclusions (Fig. 5.1).

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Fig. 5.1

Distributions of the various classes of malocclusions and associated surgeries in Korea. The distributions of Classes II and III malocclusions are similar (a), but the ratio of patients undergoing surgery is much lower for patients with Class III malocclusions (b)

Why do so few patients with skeletal Class II malocclusions elect to undergo surgery? The possible reasons for the lower surgical rate for Class II deformities, compared with Class III deformities, are listed as below:

  1. 1.

    Orthodontists and patients recognize the esthetic differences between Class II and III malocclusions

     
  2. 2.

    Preferable profile for females (small size of face)

     
  3. 3.

    Alternative orthodontic camouflage treatments are available for Class II patients

     
  4. 4.

    Alternative surgical options are available for Class II patients

     
In general, a larger mandible can have a positive esthetic effect in men, reflecting a stronger, more masculine image; a smaller mandible can give a more positive, feminine image to women who prefer smaller faces. In fact, many patients with skeletal Class II malocclusions and retrognathic mandibles visit orthodontic offices complaining of lip protrusion. Despite the lip protrusion being due to a small mandible, orthodontic camouflage treatments that involve tooth extractions produce relatively satisfactory results (Fig. 5.2).

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Fig. 5.2

Camouflage treatment of skeletal Class II malocclusion. Since skeletal anchorage began being used in the 2000s, improved lip profiles have been facilitated by tooth extractions, and lip protrusion improvements are expected to change the prominence of the chin

Additional surgical procedures, such as advancement genioplasty, can be performed after camouflage orthodonvtic treatment of skeletal Class II malocclusions (Fig. 5.3). From the patient’s point of view, these treatment options have the advantage of minimizing the burden of additional surgical operations.

../images/482096_1_En_5_Chapter/482096_1_En_5_Fig3a_HTML.jpg../images/482096_1_En_5_Chapter/482096_1_En_5_Fig3b_HTML.png
Fig. 5.3

After camouflage treatment of skeletal Class II malocclusion, advancement genioplasty was performed to achieve additional skeletal improvement. Genioplasty has the advantage of being able to be performed at any time after orthodontic treatment because it does not affect occlusion

5.2 Surgical Treatment Objective for Class II Orthognathic Surgery

Although skeletal Class II malocclusion results from mandibular undergrowth, the location of the maxilla is especially important when planning the surgical procedure. This is because the postoperative position of the maxilla also determines the postoperative location of the mandible. In planning Class II surgery, not only the mandibular position, but also combined maxillomandibular position needs to be evaluated carefully prior to surgical planning. This evaluation contains anteroposterior and vertical position of the maxilla (Fig. 5.4).

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Fig. 5.4

Anteroposterior and vertical evaluations of the maxilla are required, and the vertical evaluation requires anterior and posterior evaluations. In the case of the mandible, evaluations of the anteroposterior length of the mandibular body and the vertical length of the mandibular ramus region should be made

If a skeletal Class II malocclusion exists due to anteroposterior overgrowth of the maxilla, there are anatomical limitations for the surgical retraction of maxilla. Therefore, surgical planning that includes an anterior segmental osteotomy of the maxilla is necessary (Fig. 5.5).

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  2. and Evolution of the Surgery-First Approach
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  4. Photogrammetric Analysis in Orthognathic Surgery
  5. Surgical Planning and Three-Dimensional Simulation in Orthognathic Surgery
  6. Application of the Surgery-First Approach to Facial Asymmetry

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Mar 5, 2021 | Posted by in Orthodontics | Comments Off on Strategy for Class II Orthognathic Surgery: Orthodontic Perspective

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