2. Class II Subdivision, ToC, AJODO

CASE REPORT

Orthodontic-orthognathic surgical treatment ina patient with Class II subdivision malocclusion:Occlusal plane alteration

Teresa Pinhoa and Adriano Figueiredob

Gandra and Oporto, Portugal

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Despite the different orthodontic treatment options for patients with Class II subdivision malocclusions, the in-volvement of the skeletal structures is significant. It is desirable to combine orthodontic and surgical treatmentto achieve a stable and better esthetic result, as illustrated in this case report. The occlusal plane was canted tothe right as a part of the patient’s facial asymmetry. Consequently, a 3-mm differential impaction of themaxilla onthe left side allowed occlusal plane leveling. Mandibular rotation with advancement on the right side correctedthe right Class II malocclusion. The successful attainment of the treatment goals was accomplished throughteamwork and integration between the orthodontist and the maxillofacial surgeon. (Am J Orthod DentofacialOrthop 2011;140:703-12)

Facial asymmetries can have dental, functional, orskeletal causes (resulting from discrepancies inshape or position of at least 1 bone of the cranio-

facial complex) or a combination of factors.1,2

The main causes of mandibular lateral deviation are(1) genetic or congenital malformations (eg, hemifacialmicrosomia or unilateral cleft lip and palate); (2) environ-mental factors (eg, habits and trauma); (3) functional de-viations (eg, mandibular shifts caused by toothinterferences); (4) posterior discrepancy with unilateraleruption space deficiency in the posterior area, whichcould lead to supereruption of themolars; (5) other causes(eg, poor dental reconstructions, such as asymmetricheight of the restorative material on the left and rightsides), temporomandibular joint arthrosis, and so on.1,3-5

The degree of the subsequent jaw deformity dependsnot only on the type, intensity, extent, and chronologyof the noxious agent, but also on the site and its partic-ular involvement in growth activity.1 Class II subdivisionmalocclusions can be corrected through a variety of

ssor, Department of Orthodontics, Centro de Investigac~ao Ciencias da(CICS), Instituto Superior de Ciencias da Sa�ude-Norte/CESPU, Gandra,

gal.illofacial surgeon, Oporto, Portugal.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Teresa Pinho, Instituto Superior de Ciencias da Sa�ude-Norte/, Rua Central de Gandra, 1317, 4585-116 Gandra, PRD, Portugal; e-mail,[email protected], November 2009; revised and accepted, January 2010.5406/$36.00ight � 2011 by the American Association of Orthodontists..1016/j.ajodo.2010.01.037

treatment protocols, depending on the etiologic factorsthat produce the asymmetric dentoalveolar characteris-tics of the malocclusion.6-13 However, when there arealso severe skeletal components associated with thatmalocclusion, such as a vertical growth pattern anda retruded mandible, a combined surgical approach isoften the best treatment option.13-17

In this case, the patient had a right Class II subdivi-sion malocclusion, an upwardly canted occlusal plane onthe affected side, and a highly compensated occlusion. Or-thodontic treatment and orthognathic surgery were usedto level the occlusal plane and reposition the mandible.

DIAGNOSIS AND ETIOLOGY

The patient was a 28-year-old woman. Her chief con-cerns were her asymmetric face, retrognathic mandible,malpositioned teeth, and asymmetric appearance ofher anterior teeth. The intraoral photographs showedClass I molar and canine relationships on the left sideand Class II molar and canine relationships on the right.There was a midline discrepancy of about 5 mm, witha 1.5-mm maxillary dental midline deviation to the leftand a 3.5-mm mandibular dental deviation to the right.There was no crowding in either dental arch. There waslabial tipping of the maxillary anterior teeth, with a deepoverbite of 7 mm. The occlusal plane was canted upwardon the affected side. The maxillary and mandibulararches were narrow because of the lingual tipping ofthe teeth (Figs 1 and 2).

When the maxillary and mandibular dental midlineswere aligned on the dental casts, a complete crossbite

703

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Fig 1. Pretreatment facial and intraoral photographs.

704 Pinho and Figueiredo

on the right side and a complete scissors-bite on the leftside were created.

The panoramic radiograph showed that all third mo-lars were present (Fig 3). The lateral cephalometric anal-ysis showed a normal mandibular plane angle, a skeletalClass II malocclusion with slight retrusion of the maxilla,and a retrusive mandible (Table, Fig 4). A frontal cepha-lometric analysis confirmed the canted occlusal planewith compensatory tooth tipping and angulation ofthe posterior teeth (Fig 5).

TREATMENT OBJECTIVES

The treatment objectives for this patient were reor-ientation of the occlusal plane, decompensation of den-tal arch tipping, improvement of facial and smilesymmetry by surgical impaction of the left side of themaxilla, and correction of the mandibular retrognathiaby forward and left repositioning of the mandible.

November 2011 � Vol 140 � Issue 5 American

TREATMENT ALTERNATIVES

Based on the objectives, we could have chosen to re-orient the occlusal plane using a multiloop edgewisearchwire. However, this would not correct the positionof the maxilla and would not improve the retrognathicmandible. Consequently, no improvement of the asym-metric gummy smile could be expected. An asymmetricmaxillary impaction could significantly improve thegummy smile. Since the facial asymmetry, gummy smile,and retrognathic mandible were the patient’s major con-cerns, an orthodontic-orthognathic surgical treatmentplan was chosen.

PREOPERATIVE ORTHODONTIC TREATMENT

To assist in the correction of the posterior discrep-ancy and to facilitate the mandibular surgery, all thirdmolars were extracted 12 months before the surgery. Amulti-bracket straight-wire appliance (0.022-in slot)

Journal of Orthodontics and Dentofacial Orthopedics

Fig 2. Pretreatment dental casts.

Fig 3. Pretreatment panoramic x-ray.

Table. Cephalometric analysis

Measurement Norm Pretreatment PosttreatmentFMIA 67� 6 3� 62.1� 64.0�

FMA 25� 6 3� 23.5� 17.4�

IMPA 88� 6 3� 94.4� 98.6�

SNA 82� 6 2� 77.2� 78.6�

SNB 80� 6 2� 71.4� 76.0�

ANB 1�-5� 5.9� 2.7�

Ao Bo 2 6 2 mm 4.5 mm �1.4 mmUI/NA 22� 6 2� 16.7� 24.5�

Occlusal plane 8�-12� 6.4� 3.5�

Z-angle 75� 6 5� 70.5� 86.3�

Posterior facialheight

45 mm 50.8 mm 53.4 mm

Anterior facialheight

65 mm 74.7 mm 75.8 mm

Index post ant 0.69 0.7 0.7Overjet 2.5 6 2.5 mm 5.9 mm 2.6 mmOverbite 2.5 6 2.5 mm 6.9 mm 1.6 mmInterincisal angle 126� 6 10� 132.4� 125.3�

Ao Bo, Sagittal disparity between Ao and Bo, orthogonal projectionsof A and B on the occlusal plane; Index post ant, relationshipbetween the anterior vertical facial height and posterior verticalfacial height.

Pinho and Figueiredo 705

was bonded to all teeth. The orthodontic treatment dur-ing the first stage was for alignment and leveling to cor-rect the tooth compensations in the maxillary andmandibular arches.

Despite the difference in height of the occlusal plane,the mandibular dental midline was centered with themandible. Positioning the dental casts with the dentalmidlines coincidently produced a complete crossbiteon the right side and a complete scissors-bite on theleft side. To improve the transverse maxillary compensa-tion, we applied a heavy archwire with torque and offsetsor insets in the lateral and posterior areas (corono-

American Journal of Orthodontics and Dentofacial Orthoped

vestibular with an offset for the maxillary right and man-dibular left segments; corono-lingual with an inset forthe maxillary left and mandibular right sides).

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Fig 4. Pretreatment lateral cephalometric radiograph and tracing.

Fig 5. Pretreatment frontal cephalometric radiograph and tracing.


Photographs (Fig 6) and radiographs (Fig 7) weretaken as soon as the patient was fully decompensated,and we had obtained our orthodontic treatmentgoals.

END OF ORTHODONTIC PREPARATION

Just before the surgery, dentoskeletal alterations hadbeen made in the anteroposterior occlusal plane with anANB angle of 5.7�. The IMPA (91.4�) indicated slightprotrusion of the mandibular incisors. Overjet was 6.5mm. The vertical portion of the symphysis (15 mm)


was excessive in relation to the upper lip. Vertical excessof the maxilla on the left side was due to the canted oc-clusal plane with greater exposure of the left incisors(3 mm). Our therapeutic objectives were to reduce the in-cisor exposure on the left side by impacting the maxillaon this side and to reduce the excessive vertical symphy-sis in relation to the upper lip. The facial angle of con-vexity, glabellar vertical, and SN vertical measurementsshowed a retruded chin position. The lower facial heightratio was high (1.4). Because the standard is 1.2 to 1, themandible needed to be advanced. The frontal cephalo-metric analysis showed that the occlusal plane was


Fig 6. Facial and intraoral photographs during the presurgical orthodontic treatment. Facial photosshow the occlusal plane canted to the right. In the intraoral photos, the patient is forcing the upperand lower midlines to align.


canted upward on the affected side (to the right). Therewas greater left facial height compared with the rightside and a more obtuse left gonial angle.

The following steps were planned for this patient:maxillary left impaction (3 mm), mandibular ad-vancement (6 mm), and mentoplasty advancement(6 mm).

SURGICAL PREDICTION ON DENTAL CASTS

On the basis of the visual objective treatment sur-gical data and measurements made on the dentalcasts mounted in centric relation, cuts were plannedto simulate a 3-mm impaction of the maxillary leftside to correct the occlusal plane inclination. The in-terincisal point was used as the rotational center ofthe maxilla.

A splint was fabricated to relate the maxillary teeth intheir new position relative to the mandible. The goals ofthe splint were to provide accurate positioning of themaxilla in relation to the 3 spatial planes during surgeryand to facilitate rigid fixation.

After that, the mandibular cast was cut and advancedwith subsequent splint fabrication. The total amount offorward movement was 6 mm. The mandibular bodymoved forward asymmetrically, 10 mm on the rightside and 1 mm on the left side.


SURGICAL TREATMENT

A LeFort I osteotomy was performed to permit themaxillary correction. Bone reference points were regis-tered to improve the intrusion. An inferior nasal turbi-nectomy was performed to improve the breathingcapacity because of the maxillary impaction. To havebetter symmetry of the nasal base, the pyriform fossawas remodeled.

Advancement and rotation of the mandible were ob-tained by sagittal ramus bilateral osteotomies. In bothprocedures, rigid fixation was used with titanium platesand screws. In addition, an advancement mentoplasty of6 mm was accomplished.

TREATMENT RESULTS

A symmetric and harmonious relationship of the fa-cial soft tissues and a pleasant profile were achievedfor this patient, and a Class I bilateral molar and canineocclusion with a normal anterior relationship was ob-tained. The maxillary dental midline was aligned withthe facial midline, and there were satisfactory overjetand overbite relationships. The panoramic radiographshowed good root parallelism and bone integration(Fig 8). The cephalometric superimposition shows theamount of maxillary impaction (left side), and the man-dibular mentoplasty advancement contributed to a more


Fig 7. Presurgical lateral and frontal cephalometric tracings.

Fig 8. Posttreatment panoramic x-ray.


favorable anteroposterior chin position and improve-ment of lip competence. Cephalometrically, there wasa significant increase in mandibular length not onlyfrom the mentoplasty advancement, but also from thecounterclockwise mandibular rotation, which contrib-uted to reduce the apical base anteroposterior discrep-ancy and the profile convexity (Figs 9 and 10). Frontalcephalometric analysis showed that the canted occlusalplane was leveled, and the right and left facial heightswere more harmonious (Fig 11). To improve the symme-try of the smile, gingival recontouring and a compositereconstruction were performed on the maxillary rightlateral incisor. One year after the orthodontic treatment,the patient reported no temporomandibular joint symp-toms or signs, and a stable occlusion without relapse wasobserved (Figs 12 and 13).

DISCUSSION

Previous researchers have concluded that most peo-ple have some craniofacial asymmetry, including thosewho are perceived to be normal.18,19 Severalinvestigations have shown that remodeling changestake place at the condylar head in response to occlusalalterations.20-23

The habitual chewing side is usually the displacedside.24 In our patient, the lateral displacement of thechin can be seen in the frontal view in the intercuspalposition, but it became centered when the patient wasforced to align the maxillary andmandibular dental mid-lines. Consequently, this displacement was due to theupwardly canted occlusal plane on the affected side.Thus, by decreasing the vertical height by maxillary


impaction on the left side, we improved the mandibularposition by shifting the mandible to the left.

When orthognathic surgery is required in combina-tion with orthodontics, a nonextraction strategyshortens the orthodontic phase substantially and avoidsexcessive incisor retraction and associated flattening ofthe lip profile. However, in some patients, extractionsare necessary to reduce maxillary dental protrusionand also to recover from mandibular incisor proclinationas a consequence of mandibular arch leveling.25 In thispatient, when we leveled the mandibular curve ofSpee, the mandibular incisors were advanced; this wors-ened the mandibular incisor inclination. In spite of thischange, it was not sufficient enough to perform extrac-tions, because of the narrowing of the maxillary andmandible arches.

It has been suggested that, when treating Class IIsubdivision malocclusions, one should extract premolarsasymmetrically.6-9,11-13 In our patient, the arch length


Fig 9. Posttreatment lateral cephalometric radiograph and tracing.

Fig 10. Superimposed cephalometric tracings.

Fig 11. Posttreatment frontal cephalometric radiography.


discrepancy was not significant, so asymmetric extractionswere not planned. Also, the patient’s profile would notallow for any incisor retraction. Consequently, asymmetricextractions would not be a beneficial approach to thisproblem. On the other hand, the treatment protocolwould not improve the patient’s undesirable dentoskeletalrelationships in the frontal plane, including theasymmetric gummy smile.12 As a result of the mandibularretrognathia, we selected the surgical-orthodontic treat-ment plan.

This shows that, despite the several treatment proto-cols for a Class II subdivision malocclusion, all aspects


must be thoroughly examined before a conclusive treat-ment plan can be created. If the patient refuses surgicalintervention, a multiloop edgewise archwire could beused.4,26 However, the gummy smile and themandibular retrognathism would not be improved.Patients have reported a wide range of benefits fromorthognathic treatment, including psychosocial benefitssuch as increased self-esteem, and improved dental es-thetics and function.27-29 However, when patientsembark on treatment with unrealistic expectations, theyare more likely to be dissatisfied with the outcome.30

The aim of our preoperative orthodontic treatmentwas to allow the surgeon to perform sufficient


Fig 12. Facial and intraoral photographs 1 year after the orthodontic treatment.


mandibular advancement to compensate for the ante-roposterior discrepancy by positioning the arches ina normal transverse occlusion and by achieving sym-metric Class I molar and canine relationships. To dothis, it was necessary to put different torque and insetsand offsets at the lateral and posterior areas of themaxilla and the mandible to prevent a complete cross-bite on the right side and a complete scissors-bite onthe left side. This procedure was performed, becausethe dental casts before treatment showed the impossi-bility of having a cusp-fossa occlusion after surgery ifthe maxillary and mandibular dental midlines were co-incident. In addition, the 10-mm advancement and ro-tation of the mandibular right side was obtained bycorrection of the inclination of the maxillary incisorsand the deep overbite, and by maxillary impaction onthe left side. The interincisal point was used as the ro-tational center of the maxilla to improve the position ofthe maxillary dental midline.


It is also essential to obtain dental casts at the end ofthe orthodontic preparation to allow monitoring of therequired mandibular advancement before and duringthe surgical procedures. Dental casts permit verificationof the final occlusion in both anteroposterior and trans-verse dimensions. As a rule, a patient should not be sub-jected to surgery unless these conditions are met. Thispatient’s teeth were decompensated before surgery.Thus, the surgical outcome was not limited.31 In our pa-tient, the incisal point was well positioned in the midlinebut skewed to the right. Therefore, maxillary rotationalso allowed vertical repositioning of the dental midlineand correction of the occlusal plane inclination. To im-prove nasal permeability, we also performed an inferiorturbinectomy and septoplasty.

Skeletal facial asymmetry is common in patients withClass II subdivision malocclusion, and an asymmetricsmile requires asymmetric maxillary surgery.1,15,24 Anocclusal cant in the frontal plane (with the maxillary


Fig 13. Dental casts 1 year after orthodontic treatment.


midline deviation to the same side) is a reflection offacial asymmetry.7 Consequently, differential impactionof the left maxilla allowed leveling of the occlusal plane,and mandibular rotation with advancement on theright side corrected the Class II malocclusion on theright side.

Asymmetric surgical mandibular advancement wasnot sufficient to correct the overall mandibular length,so it was necessary to accentuate the mandibular ad-vancement with a mentoplasty.

The cephalometric treatment changes demonstratethe effect of the treatment protocol on the dentoskeletalstructures. There was an increase in mandibular progna-thism, with resultant improvements of the apical base re-lationship and facial convexity. The SN to occlusal planeangle decreased, and consequently the counterclockwisemandibular rotation, because of the maxillary left im-paction. FMA and SN-GoGn decreased, as expected,with counterclockwise mandibular rotation. The asym-metric maxillary impaction decreased the maxillary inci-sor exposure and improved the smile. Therefore, all ofthe patient’s chief concerns were accomplished.

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Documents

2. Class II Subdivision, ToC, AJODO