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This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
Presurgical orthodontic preparation was uncommon until 1960. The patients' and clinicians' desire for optimal esthetic and occlusal outcomes resulted to the most common current treatment approach presurgical orthodontic decompensation of the occlusal relationships and obtaining the normal dental alignment.
Dental decompensation so that the teeth can be placed on the basal bone irrespective of the relationship with the opposing jaw Aligning and leveling of the teeth and resolving any crowding Coordinating the upper and lower jaws Divergence of roots adjacent to surgical sites where interdental osteotomies are planned.
Presurgical orthodontic treatment reveals the true skeletal discrepancy before surgery and helps determine the required amount of the dental decompensation that limits the full correction of the skeletal deformity. This treatment approach usually results in satisfactory outcomes.
The disadvantages of orthodontic interventions before and after orthognathic surgery include the following: a long treatment time, resulting in an increase in the dental caries; gingival recession and root resorption; temporary worsening the patient's appearance; discomfort during mastication and articulation; and psychological problems due to the delays in achieving the patient's main demand, which is usually an esthetic facial appearance.
In 1995, for the first time, Skaggs suggested surgery before orthodontic treatment in patients with mild dental problems;
Behrman and Behrman claimed that the normalized surrounding soft tissues (lips, cheeks, and tongue) would settle the teeth in a better position after surgery, facilitate the remaining tooth movements, and decrease the overall duration of treatment. However, conclusive evidence is not available to substantiate these claims due to the paucity of comparative clinical trial reports.
Furthermore, since the teeth do not occlude properly after surgery, tooth movements are facilitated.
Rigid fixation of bone segments was the key to the widespread use of SFOA. Another device was the skeletal anchorage system.
In this article, we wish to provide a comprehensive overview on this approach.
The related dental literature was searched using databases such as Medline or PubMed and Google Scholar from 1959 to 2020. The search items used were “maxillofacial orthognathic surgery,” “orthognathic surgical procedure,” “surgery first approach,” “orthognathic surgery first approach,” “orthodontics,” “stability,” and “regional acceleratory phenomenon.” Relevant articles in topic and abstract were assessed and included. Case/controls and case series from 2010 to 2020 were collected in a table and compared in the article
Since each patient has an individual condition in terms of the type of malocclusion and dentofacial deformity, there are no specific criteria for the application of the SFOA technique. The patients who are candidates for this technique are those who are in a hurry to achieve esthetic results or those who want to improve both their function and esthetic appearance but cannot afford the cost of orthodontic preparation. The selection criteria largely depend on the experience and skill of the surgeon and orthodontist.
The suggested criteria for the application of this technique include the following: well-aligned to mildly crowded anterior teeth, a flat to mild curve of Spee, normal to mild proclination or retroclination of incisors (the angle of maxillary and mandibular incisors relative to the basal bone in the normal range), and minimal transverse discrepancy.
Cl III patients with mandibular prognathism and open bite are good candidates for this treatment approach because they usually have mild crowding and dental compensation.
It has been reported that the risk of the complications of SFOA is a little higher than the conventional surgical techniques due to an increase in segmental osteotomies.
Some of the disadvantages of this technique include:
Prediction of the final occlusion is the most critical challenge in this technique due to several dental interferences Patients needing tooth extraction are difficult cases with the use of this technique Any minor surgical error might affect the treatment outcome The treatment planning process is very time-consuming compared to the overall time required for treatment The patients might not be interested in continuing the orthodontic treatment, which leads to outcomes that are not favorable in terms of the main clinical aims and orthodontic stability Since the time of surgery depends on the jaw growth stage, the treatment of patients with this technique might be delayed until the completion of growth; however, the orthodontic treatment before the patient's surgery could be carried out in the final stages of growth.
Nowadays, computer-assisted methods can be used to improve the diagnostic and therapeutic SF preoperative planning by linking the virtual orthodontic planning with the virtual surgical planning.
SFOA can be implemented using two methods: the surgical-driven approach and the orthodontic-driven approach. In the former approach, both the jaw and dental deformities are corrected surgically. In the latter approach, the jaw deformity is corrected surgically, and the dental deformity is corrected with orthodontic treatment Surgery-first orthognathic approach compared to the conventional orthognathic approach (red arrow: orthodontic movement; purple arrow: surgical movement).
Presurgical preparation
Regarding postsurgical orthodontics, presurgical preparation can be carried out in different ways:
Placement of surgical arch bar, without orthodontic archwire Placement of anchor screws, without orthodontic archwire Placement of light round or light rectangular wire (with or without screws or anchor plates) Placement of conventional passive, rectangular wires attached with surgical hooks (with or without anchor screws).
Since the surgical hooks cannot be placed on light round or light rectangular wires, extra anchor screws and plates are used for maxillomandibular fixation (MMF).
Researchers prefer the use of anchor screws to orthodontic hooks for postoperative MMF and elastic traction.
Some orthodontists use passive stainless steel wires adapted to all the teeth to prevent any tooth movements until the stability of determined positions of the jaws has been achieved,
Alternatively, Baek et al. suggested that the archwire can be directly bonded to tooth surfaces a few days before surgery to perform as an arch bar. Although this technique is comfortable for the patient, it is difficult to remove the bonded archwire and replace it with a bracket during the healing period after surgery.
To avoid severe postoperative occlusal instability, orthodontists can remove occlusal interference by simple occlusal adjustment in mild cases and opening the bite in more severe cases.
Model surgery
In the model surgery, the maxillary and mandibular casts are placed in the correct molar relationship with positive overbite. Contrary to the conventional technique, in which the decompensated incisors are used as a guide for the prediction of the final occlusion, here, the molar teeth are used as a guide. In cases of nonextraction or bimaxillary first premolar extraction, the molar relationship is adjusted at Cl I relationship. In patients with the extraction of mandibular first premolars, it is adjusted at Cl III relationship, and in patients with the extraction of maxillary first premolars, it is adjusted at Cl II relationship.
The vertical dimension in their guidelines suggests deep overbite or posterior open bite for preventing bite opening from dental alignment and arch leveling after surgery because the posterior open bite is easier to correct than anterior open bite after surgery. The posterior open bite is also helpful for correction of posterior crossbite from buccoversion of maxillary second molars.
In the transverse dimension to prevent positional asymmetry, the maxillary and mandibular jaw (alveolar base) midlines must be coincident or close to it. Since the surgical occlusion is sometimes set with dental midline off due to dental arch asymmetry, they suggested surgical occlusion to be set as coordination of jaw midlines instead of dental midlines.
Baek et al. used a different technique for the model surgery in skeletal Cl III cases with two jaws surgery. In this technique, it is necessary to use a semi-adjustable articulator. The dental and base sections of the study models are separated for skeletal changes and alignment of the teeth, and after making the changes and modifications, intermediate and final surgical wafers are prepared.
In this technique, the orthodontist must have experience and confidence to be able to move the teeth similar to the results of the model surgery.
Postsurgical orthodontic treatment
There is no consensus on the time of orthodontic treatment initiation. Since dental compensation in the dental arches has not been eliminated before surgery, it is expected that the occlusion will be very unstable due to the presence of premature contacts. Some authors begin leveling the dentition to eliminate occlusal interferences and coordinate the arches immediately. Replacing heavy stabilizing wires with light and flexible wires immediately after surgery has been suggested to shorten the duration of postsurgical orthodontic treatment.
Some others also have emphasized that the postsurgical orthodontic treatment should begin as soon as possible to maximally benefit from the advantages of the regional acceleratory phenomenon after surgery.
Orthopedic appliances, such as the facemask or chip cup, might be used in Cl III patients for the maintenance of the jawbone position during orthodontic tooth movements.
Dental decompensation in the anteroposterior and vertical dimensions in class III patients
Two techniques are available to decompensate the proclined upper incisors in Cl III patients: by extraction of the maxillary first premolar teeth and anterior segmental osteotomy, or by clockwise (CW) rotation of the maxilla during LeFort I osteotomy (preferred approach) To decompensate the moderately retroclined and crowded lower incisors, the molars can be set up in Cl I relationship and excessive overjet can be resolved after surgery by aligning the anterior teeth To decompensate the severely retroclined and crowded mandibular incisors, after mandibular first premolar extraction, the molars can be placed in Cl III relationship, and the excessive overjet can be resolved after surgery by aligning the anterior teeth It is advisable to flatten moderate to deep curve of Spee in the mandible before surgery or surgically with anterior segmental osteotomy to prevent upward and forward rotation of the mandible after surgery. Upward and forward rotation of the mandible improves the chin projection in Cl II mandibular retrognathism patients; however, it worsens the chin projection in Cl III patients with mandibular prognathism patients. Alternatively, it is possible to intrude the lower incisors and extrude upper incisors simultaneously to prevent the upward and forward rotation of the mandible after surgery A chin cup can be used during the 3-month period after surgery to prevent skeletal mandibular relapse.
Dental decompensation in the anteroposterior and vertical dimensions in class II patients
In moderate to deep curve of Spee and proclined lower incisors in Cl II mandibular retrognathism patients, it is possible to level and intrude the anterior teeth during anterior segmental osteotomy; therefore, the mandible can be adequately advanced Alternatively, it is possible to advance the mandible to an edge-to-edge incisors relationship without posterior teeth occlusal contact. Then, the mandibular anterior teeth can be intruded after surgery, which is followed by the upward and forward rotation of the mandible, providing the contact of the posterior teeth, and improving the chin projection The upper incisor inclination is important in deciding for extracting or not extracting teeth in the maxilla. If the angle of maxillary incisors relative to the occlusal plane is <53°–55°, tooth extraction should be considered.
It has been reported that the dentoskeletal relapse is related to factors such as the fixation method of the bone plates, muscle contraction, maxillary constriction, the curve of Spee, and increased overjet and overbite. Better stability has been observed in patients with a flat curve of Spee and smaller overbite. Some authors have reported a relationship between the amount of relapse and the surgical technique and the sequence of orthodontic treatment with surgery. In the SFA, more favorable arch coordination can be achieved after elimination of the functional muscular forces in an unfavorable skeletal position. However, this method is technique-sensitive, and the stability of treatment outcome can be affected by factors such as unfavorable fixation of jaw segments, lack of integrity of the osteotomized bone segments during healing, a loose IMF, an improper position of the condyle relative to the cranial base, improper placement of the proximal and distal segments which leads to torquing of the proximal parts, and an unfavorable splinting. In addition, the CR-CO discrepancy has a pivotal role in the equilibrium of the functional matrix.
Studies have not shown any significant differences in the transverse dimension stability between the SFOA and the conventional approach. Liao et al. reported greater anti-CW rotation in the vertical plane, while Kim et al. reported greater CW rotation in the mandible of patients undergoing SFOA, compared to those who underwent conventional approach. In the sagittal plane, Kim et al. reported greater relapse in the SFOA approach compared to conventional approach.
Although the SFA has some advantages, such as shortening the duration of treatment and rapid response to the patient's chief complaint, it has also some limitations. In particular, occlusion cannot have a guiding role during surgery. Therefore, patient/case selection, appropriate diagnosis, accurate prediction of the postoperative outcomes, and simulation with the model surgery are of utmost importance. The knowledge and experience of the orthodontist and surgeon have a pivotal role in this technique.
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