Orthognathic Surgical Approach for Management of Skeletal Class II Vertical Malocclusion.

The current era of orthodontics has evolved from regular dental corrections to achieve the most needed harmony between functional stability and esthetics enhancement of craniofacial structures. The "desire" for attaining this harmony led to the birth of orthognathic surgeries. The orthognathic approach has undergone a paradigm shift through the years, from correcting the skeletal component to addressing the soft tissues, thus optimizing esthetic outcome. This present case report is of a patient with skeletal Class II malocclusions with vertical maxillary excess (VME), managed by multidisciplinary treatment approach. The treatment progressed through presurgical orthodontics with premolar extraction followed by bi-jaw surgery. The outcome resulted in a phenomenal change in the profile by establishing a Class I skeletal base with a stable occlusion.

Introduction

The field of orthognathic surgery since its inception in 1849[1] has gained its charm in 1989 through EH Angle and Vilray Papin Blair[23] when they performed and documented the first “double resection of the mandible” in a patient with a prognathic mandible. Later, Hugo Lorenz Obwegeser was the first to complete sagittal split osteotomy of the mandibular ramus (1953),[4] following which he introduced the osseous genioplasty (1957) using intraoral approach, and he also developed the modern type Le Fort-I osteotomy (1965).[56] Since then, orthognathic approach has metamorphosed from correcting the skeletal problems to addressing the needs of enhancing soft tissue balance.

Severe skeletal Class II malocclusions have to be addressed by surgical interventions to achieve an optimum skeletal and soft tissue balance. The primary goal of surgical orthodontic treatment lies in the repositioning of maxilla and mandible vertically and sagittally as per the need of the patient's esthetic requirement which is often followed by a genioplasty procedure for stability in the lower incisor region.

Previous reports to treat vertical maxillary excess (VME) using orthognathic approach by West and Epker and McNeill[78] in 1975 and Schendel et al. in 1976[910] have employed only Le Fort-I procedures. This procedure often results in autorotation of mandible which allows a mild forward position of the lower jaw. The present case report describes a bi-jaw surgical intervention which has been advocated to correct the deficiencies in all three planes of space.

Case Report

Diagnosis and etiology

A 20-year-old patient presented himself at the Department of Orthodontics, looking for a solution for his unesthetic facial appearance and protruding teeth. He was in good health and had a history of minor dental trauma resulting in fractured 11 about 4 years ago. Clinical examination revealed [Figure 1], mesocephalic head pattern, the mesoprosopic facial pattern associated with a severe convex profile and posterior divergence, retrogenia, and chin deviation toward the right side. On rest, the upper lip was incompetent with an incisor show of 6 mm; smile exhibited complete incisor show along with 1 mm of gingival exposure. The upper dental midline was shifted to the right by 2 mm.

Figure 1

Pretreatment records of a 20-year-old male patient with Class II Division 1 subdivision malocclusion with an orthognathic maxilla with vertical maxillary excess and retrognathic mandible with chin deviation and deficiency

Intra oral examination reveals an end-on relationship in reference to the molars on right and left side. Whereas the canine relationship reflected a class i on the right and end-on on the left. Furthermore, severely proclined maxillary incisors, severely crowded mandibular incisors with lingually blocked out 42, moderate proclination, and the lower dental midline shift toward the right. The overjet and overbite were 12 mm and 7 mm, respectively.

The cephalometric analysis highlighted a severe Class II skeletal base with an orthognathic maxilla and a retrognathic mandible (SNA-860, SNB-760, ANB-100, Witt's appraisal +9 mm) with an average mandibular plane angle (FMA-270). The vertical parameters (N to ANS-56 mm, N to PNS-53 mm) indicated anterior downward pitch in the maxilla resulting in the vertical anterior maxillary excess. The maxillary incisors were severely proclined (U1 to NA-12 mm and 370, U1 to SN-1240) and mandibular incisors were proclined (L1 to NB-13 mm and 370, IMPA-1050). The panoramic radiographs showed no missing teeth or any root resorption and horizontally impacted third molars. No signs and symptoms of temporomandibular joint disorder were elicited through the questionnaire or clinical examination.

Based on these findings, the diagnosis was dentoalveolar Angle's Class II division I subdivision malocclusion on Class II skeletal base owing to an orthognathic maxilla with VME and a retrognathic mandible with retrogenia and deviation toward the right.

The objectives of treatment involved were as follows:

To correct the soft tissue profile and smile esthetics

To correct the skeletal discrepancies

Achieve stable and functional occlusion with a normal overbite and overjet

Restore the fractured 21 to optimize the smile esthetics.

Treatment plan and alternatives

The following treatment plans were discussed with the patient considering the treatment objectives and correlating with patient's requirements.

The initial treatment plan for the patient fullfilling the treatment objectives was an orthodontic-surgical combined approach; this involved extraction of maxillary second premolars and mandibular first premolars for allowing decompensation followed by bi-jaw surgery combining Le Fort I osteotomy to bring about the maxillary impaction and rotational bilateral sagittal split osteotomy for mandibular advancement combined with sliding genioplasty for further profile enhancement. The alternate plan was an orthodontic camouflage consisting of intrusion and retraction followed by extraction of maxillary first premolars and single blocked out incisor extraction in lower arch to finish the molar in Class II molar and canine in Class I relationship. However, the prognosis would be compromised considering the severity of the skeletal discrepancy. On weighing the risks and benefits of both the alternatives, the patient chose the ideal treatment option, which relieved him from the psychological impact caused during adolescence.

Treatment progress

Treatment was carried out in three phases:

Presurgical phase

Surgical phase

Postsurgical phase.

Presurgical phase

The orthodontic treatment was initiated with extractions of second premolars in the maxillary arch and first premolars in the mandibular arch to facilitate decompensation; following this, the fixed appliance treatment was commenced using 0.022 × 0.028 MBT prescription. After initial leveling and alignment, the extraction space closure was carried out using friction mechanics on a 0.019 × 0.025 SS, which resulted in improvement of inclination of the upper anterior and relieved the crowding in the mandibular arch [Figure 2].

Figure 2

At the end of presurgical orthodontics

Surgical phase

Final and intermediate splints were fabricated using the simulated mock surgery protocol. The bi-jaw surgery involving Le-Forte I maxillary impaction of 3 mm was first carried out, the patient's occlusion was stabilized using intermediate splints, followed by rotational bilateral sagittal split osteotomy for the mandibular advancement of 6 mm which was plated using the final splints. Following removal of the stabilising splint, the acquired occlusion was checked with the predetermined occlusion. Finally, the profile enhancement was carried on by advancing the chin through sliding genioplasty by 6 mm.

Postsurgical phase

Postsurgical orthodontics was continued after surgery to close minor spaces distal to canines in both upper and lower arches. The goals of this phase of treatment were to rehabilitate and restore the neuromuscular function and achieve final occlusal settling. Occlusal function and settling were significantly improved through the use of intermaxillary elastics. Selective occlusal grinding was performed to finetune the occlusion. The postsurgical phase lasted for 8 months.

Results

The assessment of the treatment outcomes showed well-aligned dentition. Extraorally, the patient demonstrated a harmonious smile and well-balanced facial profile and competent lips. Evaluation using cephalometric analysis [Table 1] and superimposition confirmed an excellent profile change from Class II to Class I skeletal base (SNA-830, SNB-800, and ANB-30). The superior maxillary impaction has attributed to decrease in anterior and posterior vertical maxillary heights thereby reducing the total VME which had prevailed in pretreatment, this in turn reduced gummy smile which was seen pretreatment and had been exaggerated following presurgical orthodontic decompensation. There was a reduction in proclination in the maxillary and mandibular incisors (U1 to NA-250, L1 to NB-260) on posttreatment. The intraoral photographs and study model revealed a well-settled occlusion with Class I molar and canine relationship on both the sides. Ideal overjet and overbite were established posttreatment [Figure 3]. Postdebonding, the retention protocol consisted of Begg's wrap around in the maxilla and fixed lingual retainer in the mandible. The overall treatment duration lasted for 20 months, following which the patient was delighted with the treatment results and improved facial appearance.

Table 1

Comparison of cephalometric values

Figure 3

Posttreatment records

Discussion

Orthodontic treatment of VME without an anterior open bite is a challenging problem and much more difficult to treat than when combined with anterior open bite. Molar intrusion causes counterclockwise rotation of the mandible resulting in automatic correction of an anterior open bite. On the other hand, a more significant amount of intrusion of the anterior teeth than posterior teeth should be considered for treatment of VME with the normal overbite, as suggested by Fish et al.[11] in 1979. The superior reposition of maxilla causes an autorotation of mandible and upward and forward movement of pogonion. A study by Sperry et al.[12] stated that 5 mm of maxillary impaction brought about 1.5 mm of forward and upward movement of pogonion. Considering the amount of underlying skeletal discrepancy contributed by retrognathic mandible and the lower facial height being average, the authorization might further reduce the facial height; hence, mandibular advancement was considered necessary for optimal correction of the profile. Horizontal sliding genioplasty was undertaken to correct the chin deviation and the profile enhancement. The advancement of 7 mm was opted also considering the stability of the mandibular advancement taking into the muscular remodeling of attachment muscles structures into the mandible, as per Simmons et al. in 1992. The patient profile worsened after presurgical orthodontic phase due to the reduction in the amount of maxillary anterior proclination which increased the amount of gingival exposure during the smile. However, this was significantly corrected, and esthetics was enhanced immediately postsurgery which in turn was a motivating factor for the patient. The final treatment outcome was highly successful as the enhancement of facial esthetics combined with well-stable occlusion was established. The long-term follow-up of the patient resulted in excellent stability.

Conclusion

Combined orthognathic-surgical approaches for severe skeletal discrepancies which are complicated by soft tissue adaptations and the bi-jaw approach combined with adjunctive profile enhancement procedures resulted in better harmony between the underlying skeletal framework and soft tissues. Furthermore, this approach offered conducive neuromuscular overlay which along with a stable occlusion provided good postoperative stability.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.