Application of the Surgery-First Approach in Patients with Class II Dentofacial Deformities

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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_12

12. Clinical Application of the Surgery-First Approach in Patients with Class II Dentofacial Deformities

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

Class IIClass II dentofacial deformityRetrognathismObstructive sleep apneaCounter clockwise rotation

To date, our group has been reluctant to apply the surgery-first approach to patients with moderate to severe degrees of Class II dentofacial deformities. The unique features of Class II malocclusions include the large degree of centric relation-centric occlusion (CR-CO) discrepancy, the possibility of condyle resorption, and the unstable mandible position (Fig. 12.1). To solve these problems, my orthodontist and I have tried to find a stable mandible position using physical therapies, such as a CR stabilizing splint, and traditional orthodontic treatment. To do this, we need to know the patient’s exact condyle position, which corresponds to the CR position. For example, Class II patients tend to have wider CR-CO discrepancies because the mandibular condyle can be luxated from the glenoid fossa for the CO. On the other hand, patients with Class III dentofacial deformities cannot retrude their mandibles because the condyles are already located in the glenoid fossa for CO, which leads to a lesser degree of CR-CO discrepancy.

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Fig. 12.1

(a) Centric Relation-Centric Occlusion (CR-CO) discrepancy is the major determining factor for the successful surgical management in Class II dentofacial deformity. (b) The transverse disharmony between the upper and lower arch could be an obstacle in Class II dentofacial deformity. (c) How to manage the temporomandibular joint would be the key for the successful management

For these reasons, time is required to stabilize the mandible, including determining the true CR, in patients with Class II malocclusions. In this sense, if we apply the surgery-first approach, we would not be able to deal with this problem. This is the reason why our group has been reluctant to apply the surgery-first concept to patients with Class II dentofacial deformities (Figs. 12.2, 12.3).

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Fig. 12.2

Typical patient with a Class II dentofacial deformity and a Class II malocclusion. The unique features of the Class II malocclusion include a large degree of centric relation-centric occlusion discrepancy, a possibility of condyle resorption, and an unstable mandible position

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Fig. 12.3

The clinical application of the surgery-first approach in a patient with Class II dentofacial deformities inevitably results in an anterior crossbites, immediately after the orthognathic surgery

Otherwise, the application of the surgery-first concept could be possible. For example, if a patient has a relatively healthy condyle and minimal CR-CO discrepancy, orthognathic surgery could be applied. Someone might ask us how to manage the anterior crossbite. The anterior crossbite that develops after surgery-first orthognathic surgery in a patient with Class II malocclusion can be resolved with orthodontic treatment. Dental compensation can also help the postsurgical orthodontic treatment. However, we should keep in mind that if the orthodontist does not appropriately manage the anterior teeth during the postsurgical orthodontic treatment, the upper anterior teeth could suppress the lower anterior teeth and lead to a labial version of the lower teeth. We believe that careful orthodontic management can solve this kind of problem.

In summary, although our group is reluctant to apply the surgery-first concept in our practice, we are trying to overcome the issues of concern and apply the concept, for limited indications, in patients with Class II dentofacial deformities.

Rather, we have focused on the counterclockwise rotation of the maxillomandibular complex, based on the posterior nasal spine (PNS) lengthening, which is different from the traditional counterclockwise maxillomandibular complex (MMC) rotation that is based on ANS impaction. Particularly in cases where the Class II malocclusions are accompanied by obstructive sleep apnea (OSA), we have been applying MMC counterclockwise rotational movement rather than traditional maxillomandibular advancement. Below, I will introduce our concept for the management of Class II malocclusions in our practice.

12.1 Counterclockwise Rotational Movement of the MMC in Patients with Class II Malocclusions Accompanied by OSA Without Maxillary Advancement

Although maxillomandibular advancement (MMA) is an orthognathic surgical procedure used to manage OSA in individuals who are noncompliant with continuous positive airway pressure therapy, simple MMA suffers from aesthetic outcome problems in Asian patients with preexisting dentoalveolar protrusions. Our current, prospective investigation describes the changes in the posterior pharyngeal space and the aesthetic outcomes after counterclockwise rotational orthognathic surgery, which has known difficulty in maintaining skeletal stability in patients with skeletal Class II deformities and OSA (Fig. 12.4, 12.5).

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Fig. 12.4

Traditional orthodontic-first approach for a patient with a Class II dentofacial deformity accompanied by idiopathic condyle resorption. The unique features of Class II malocclusions include a large degree of centric relation-centric occlusion (CR-CO) discrepancy, a possibility of condyle resorption, and unstable mandible positioning. To solve these problems, my orthodontist and I have tried to find a stable mandible position using physical therapies, such as a CR stabilizing splint and traditional orthodontic treatment. To do this, we need to know the patient’s exact condyle position that corresponds to the CR position

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Fig. 12.5

The comparison between the traditional orthognathic approach and the surgery-first orthognathic approach

12.2 Preliminary Investigation

MMA is an orthognathic surgical procedure used to manage OSA in individuals who are noncompliant with continuous positive airway pressure (CPAP) therapy [1, 2]. MMA is also a site-specific procedure performed to create an enlarged posterior airway space (PAS) at multiple anatomic levels, including at the nasopharynx, oropharynx, and hypopharynx levels [3, 4]. The procedure has been shown to significantly improve OSA, with reported short-term success rates of 75–100% [5, 6]; its clinical effectiveness is considered to be comparable with that of CPAP. Preliminary reports further suggest that much of its short-term benefit is maintained long term. From an aesthetic point of view, however, MMA often does not seem to be satisfactory. Generally, to obtain satisfactory functional outcomes, >10 mm of MMA is needed. Although the correction of OSA is important, there appears to be excessive sacrifice of facial aesthetics. This may be why MMA has not received overwhelming praise from the general public, despite its efficacy. For this reason, we focused our present study on showing how OSA can be corrected without sacrificing, and perhaps enhancing, facial esthetics. We investigated how aesthetics and function could be simultaneously restored and enhanced. Our solution was the counterclockwise rotation of the MMC, during orthognathic surgery, for the correction of OSA. This report describes the functional and aesthetic outcomes after counterclockwise rotational orthognathic surgery in Asian patients with skeletal Class II deformities and OSA, based on preoperative and postoperative cephalometry.

This prospective study, approved by our institutional review board, investigated the functional and aesthetic outcomes of patients suffering from OSA following counterclockwise rotational orthognathic surgery. We included patients with skeletal Class II deformities who underwent orthognathic surgery, between March 2013 and December 2014, at one tertiary care institution. Patients were chosen based on the following inclusion and exclusion criteria. The inclusion criteria included a preoperative polysomnography diagnosis of OSA and consultation with an ear, nose, and throat surgeon. We excluded patients with severe dental crowding or arch discrepancies and those who were syndromic or had cleft-related dentofacial deformities. Patients without at least 12 months of follow-up were also excluded [5].

The orthognathic surgery steps were similar to those in the conventional procedure for patients with skeletal Class II deformities. Where mandibular advancement, using sagittal split ramus osteotomy (SSRO), was initially performed with clockwise MMC rotation followed by the LeFort I osteotomy, a counterclockwise rotation of the MMC with mandibular advancement, using SSRO, seems to be better suited for many Asian patients to prevent excessive dentoalveolar protrusion and retain facial aesthetics. Because we performed counterclockwise rotational orthognathic surgery, the mandible-first approach was chosen to maximize the accuracy of the orthognathic surgery. Fixation of the proximal and distal mandibular segments was achieved using the rigid fixation method and double miniplates. Preoperatively, three-dimensional (3D) computed tomography scans were obtained and cephalometric and polysomnographic analyses were conducted. The same examinations were repeated immediately after and 6 months after the orthognathic surgery. Subsequently, changes in cephalometric landmarks, including the angle of the lines connecting the sella, nasion, and point A (SNA); the angle of the lines connecting the sella, nasion, and point B (SNB); the angle of the lines connecting point A, the nasion, and point B (ANB); and the angle of the mandibular plane to the lower incisor (IMPA), were compared among the preoperative, immediate postoperative, and 6-month postoperative periods. To analyze the airway dimensions indirectly, lateral cephalometric changes in airway parameters were also evaluated. The PAS parameters included the distance from the most posterior soft palate point to a collinear point on the posterior pharyngeal wall (PSP-AP), the distance from the point crossing the inferior border of the mandible, in the posterior area of the tongue, to a collinear point on the posterior pharyngeal wall (PTO-AP), and the distance from most superior point of the epiglottis to a colinear point on the posterior pharyngeal wall (E-AP) (Fig. 12.1). The vertical upper airway length (UAL) was also measured as the distance from the most posterior point of the soft palate to the most superior point of the epiglottis. The positions of the cephalometric landmarks were compared at the following intervals: T0, preoperative period; T1, immediate postoperative period; and T2, 6-month postoperative period, and included the relapse ratio (T2–T1/T1–T0). Digitization of the cephalometric tracings (V-ceph, Osstem Implant, Seoul, Korea) was performed by two craniomaxillofacial surgeons. To evaluate patient facial appearance perception, each patient completed a questionnaire one year after the surgery. A visual analog scale (VAS: 0, absolute dissatisfaction; 10, full satisfaction) was used to assess the change in patient facial appearance perspectives. All statistical analyses were performed using SPSS software (SPSS, Chicago, IL, USA). Mann–Whitney U-tests were used to compare pre- and postoperative airway status. All reported p-values were two-sided, with p < 0.05 being considered significant (Table 12.1).

Mar 5, 2021 | Posted by in Orthodontics | Comments Off on Application of the Surgery-First Approach in Patients with Class II Dentofacial Deformities
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