orthognathic treatment for a patient with class iii …...class iii malocclusion and surgically...

CASE REPORT

Orthognathic treatment for a patient withClass III malocclusion and surgicallyrestricted mandibleMarcos Janson,a Guilherme Janson,b Eduardo Sant’Ana,c Douglas Tibola,d and Décio Rodrigues Martinse

Bauru, Brazil

This case report describes the orthodontic-surgical treatment of an adult with Down syndrome and a ClassIII skeletal malocclusion with posterior open bite, horizontal facial pattern, missing mandibular posteriorteeth, and surgical restriction of the mandible. (Am J Orthod Dentofacial Orthop 2009;136:290-8)

Class III malocclusion is a difficult anomaly tounderstand. Studies conducted to identify theetiologic features of Class III malocclusion

showed that the deformity is not restricted to the jawsbut involves the total craniofacial complex.1,2 Mostsubjects with Class III malocclusions have combina-tions of skeletal and dentoalveolar components.3 Thefactors contributing to the anomaly are complex. Theycan act synergistically or in isolation, or they mightcancel each other.2

Treatment of skeletal Class III malocclusion in anadult requires dentoalveolar compensation or combinedorthodontic and surgical procedures, with the aim toachieve normal occlusion and improve facial esthetics.4-6

However, not every patient is amenable to all necessarysurgical procedures.7-10 Therefore, the objective of thisarticle is to present the treatment of a skeletal Class IIImalocclusion in a patient with mild Down syndrome anda horizontal growth pattern, absence of several posteriorteeth, hypertrophied musculature, and mandibular alveolarbone reduction that restricted surgery in the mandible. Thedentoalveolar orthodontic compensation and surgical al-ternative are discussed.

aPrivate practice, Bauru, Brazil.bProfessor and head, Department of Orthodontics, Bauru Dental School,University of São Paulo, Bauru, SP, Brazil.cAssociate professor, Department of Oral and Maxillofacial Surgery, BauruDental School, University of São Paulo, Bauru, SP, Brazil.dGraduate student, Department of Orthodontics, Bauru Dental School, Univer-sity of São Paulo, Bauru, SP, Brazil.eProfessor, Department of Orthodontics, Bauru Dental School, University ofSão Paulo, Bauru, SP, Brazil.The authors report no commercial, proprietary, or financial interest in theproducts or companies described in this article.Reprint requests to: Guilherme Janson, Department of Orthodontics, BauruDental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla9-75, Bauru - SP - 17012-901, Brazil; e-mail, [email protected], January 2007; revised and accepted, January 2007.0889-5406/$36.00Copyright © 2009 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2007.01.039

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DIAGNOSIS AND ETIOLOGY

An 18-year-old man with mild Down syndromecame for orthodontic treatment at private orthodonticoffice of Marcos Janson. His main complaint wasdifficulty in chewing. He had a skeletal Class IIImalocclusion with bilateral posterior crossbite, aconcave facial profile, and facial asymmetry (Figs1-4 and Tables I and II) The absence of the mandib-ular right first and second molars and left first molaraggravated his occlusal problems. In the mandible,the left deciduous canine and the right third molarand the left second and third molars were present.The periodontal tissues were healthy.

TREATMENT OBJECTIVES

The treatment objectives were to surgically advanceand rotate the maxilla clockwise, retract and produce anintrabasal clockwise rotation of the mandible to rotatethe occlusal plane, and correct the anterior and poste-rior crossbites. In addition, the maxillary and mandib-ular dental arches would be aligned, improving thepatient’s facial profile. In the mandible, extraction ofthe right third molar, the left second and third molars,and the left deciduous canine would also be necessary.Dental implants would replace the missing mandibularmolars. These procedures would improve his chewingefficiency.

TREATMENT ALTERNATIVES

Three alternatives were presented to the patient.The first consisted of dental compensation by removingthe deciduous canine and closing the spaces with ClassIII intermaxillary elastics. Although this approachwould correct the anteroposterior and transverse prob-lems, it could compromise the posterior occlusion andthe smile line. Because of the missng mandibularposterior teeth, the use of Class III elastics could

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Fig 1. Pretreatment facial and intraoral photographs.

aggravate the mandibular occlusal plane inclination,worsening the posterior open bite. Moreover, the max-illary occlusal plane would rotate counterclockwise andcompletely hide the maxillary anterior teeth.11-13

The second option included surgical advancementand clockwise rotation of the maxilla, and mandibularreduction with intrabasal clockwise rotation. Thisseemed to be the best option to obtain the treatmentobjectives. However, the absence of posterior teeth inthe mandible for many years caused severe resorptionand atrophy of dentoalveolar height and width, leavinga thin residual basal bone. Additionally, the patient hadstrong masticatory muscles and Down syndrome,which caused some uncertainty about his compliancewith postoperative care.14,15

The third treatment option was to advance androtate the maxilla clockwise without surgical interven-tion in the mandible. Postsurgical orthodontic extrusionof the mandibular premolars would be necessary toreach the occlusal contacts. Because of the limitationsof the first 2 options, the patient and his parents chosethis alternative.

TREATMENT PROGRESS

Preoperative orthodontic preparation was performedwith conventional 0.022-in edgewise appliances. Afterextraction of the mandibular left deciduous canine, level-ing and alignment began with 0.016-in nickel-titaniumarchwires, followed by 0.016-, 0.018-, and 0.020-instainless steel round archwires up to 0.019 � 0.025-inrectangular archwires. In the leveling and alignmentstage, the archwires were coordinated, and the mandib-ular left permanent canine was moved to the deciduouscanine extraction space with an elastic chain on theanterior teeth and an open-coil spring distal to thecanine (Figs 5 and 6). This procedure took 12 months.After alignment and implant-site preparation, 0.019 �0.025-in stainless steel rectangular archwires wereplaced in the maxillary and mandibular arches inpreparation for surgery. The surgery consisted of max-illary advancement to obtain a Class I occlusion andproper overjet.

Postoperatively, since it was not possible torotate the mandibular plane, a posterior open bite

remained. To achieve the proper occlusal contacts,vertical intermaxillary (1/8 in) and Class III elastics(5/16 in) were used (Fig 7). The final occlusalrelationship was retained with a maxillary Hawleyplate and a mandibular canine-to-canine retainer. Apartial removable prosthesis was placed after treat-ment to rehabilitate the edentulous area. Osseointe-Fig 3. Pretreatment cephalometric tracing.

Fig 4. Pretreatment panoramic radiographic.

Fig 2. Pretreatment study models.

American Journal of Orthodontics and Dentofacial OrthopedicsAugust 2009

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Fig 5. Intraoral photographs during treatment showing tooth movement to prepare site for implantplacement in area of newly formed alveolar bone, between the canine and the first premolar.

Fig 6. Presurgical intraoral photographs.

Fig 7. Postsurgical intraoral photographs showing vertical intermaxillary elastics for posteriordentoalveolar extrusion.


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grated implants were rejected by the patient’s parentsbecause a bone graft would be necessary, with increasedtreatment costs.

RESULTS

The posttreatment photographs show improvementin the facial profile and elimination of facial asymmetrycaused by the malocclusion. The patient was satisfied

with his teeth, profile, and smile line. The final occlu-sion showed a Class I canine relationship on both sides.The maxillary right third molar and the mandibular leftsecond and third molars were not removed because ofthe complexity of the procedure. The mandibular rightthird molar was extracted (Figs 8-11).

In addition to maxillary protrusion, the maxillaryand mandibular incisors were labially tipped and


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Fig 8. Posttreatment facial and intraoral photographs.

slightly protruded (Table II). The superimposition ofthe cephalometric tracings show that the maxilla wasadvanced with the orthognathic surgery, and the man-dible experienced minimal counterclockwise rotationand protrusion (Fig 12). A considerable reduction in thenasolabial angle was observed. Facial concavity de-creased, maxillary incisal exposure at rest was in-creased, and the lips were protruded.

The orthodontic tooth movement provided success-ful alveolar bone development in the horizontal andvertical planes for implantation of 1 dental implantdistal to the mandibular left canine. Occlusal equilibra-tion was performed after appliance removal to refinethe interocclusal contacts. Root resorption was minimal(Fig 11).

DISCUSSION

The treatment protocol produced a satisfactoryocclusal and esthetic result for the patient and hisparents, as demonstrated by their attitude at the end oftreatment. Maxillary advancement provided good sup-port for the upper lip, filled the soft-tissue midface, andfavorably improved the patient’s profile. Facial profile

change is important in syndromic patients, since 1characteristic is a retruded midface.14,16 The surgicaladvancement of the maxilla also provided a satisfactoryanteroposterior relationship with the mandible andimproved maxillary incisor exposure. Better dentalrelationships also improved the functional mandibularasymmetry on the left side that was caused by theanterior and posterior crossbites (Fig 1).15,17

Ideally, mandibular surgery also should have beenperformed to rotate the mandible clockwise, decreasingthe chin prominence and reducing the vertical distancebetween the posterior teeth. The posterior open bite mighthave been caused by the hypotonic tongue, which hadtooth imprints along its lateral border.18,19 Surgery of themaxilla aggravated the posterior open bite (Fig 6), butatrophy of the mandibular alveolar rim and the rigidmasticatory muscles were contraindications for theprocedure. Also, the syndrome elevated the surgicalrisks, especially for necessary postoperative patientcare. Fortunately, facial and occlusal analysesshowed that surgical intervention in the maxilla withcomplementary orthodontic treatment in the mandib-ular arch could produce a satisfactory result.4,5,20

The impacted mandibular left second and thirdmolars should have been removed, but the surgicaldifficulty experienced with the right third molar extrac-tion and the reduced bone width eliminated the proce-dure. In addition, patients with Down syndrome couldhave blood alterations that might cause complications

Fig 9. Posttreatment study models.

Fig 10. Posttreatment cephalometric tracing.

Fig 11. Posttreatment panoramic radiograph.


Janson et al 295

such as infections or healing problems. These patientshave a reduced resistance to infections because ofdeficiency of blood circulation in the terminal vascularareas, defects of T-cell maturation, problems in thepolymorphonuclear leukocytes and neutrophil chemo-taxis, and deficits in phagocytosis and intracellulardestruction.7-9

Because of the limited number of natural teeth inthe mandible and the small mandibular body height inthe molar area, the mandibular left deciduous caninewas extracted to mesialize the permanent canine, open-ing a space between it and the first premolar to receive

Table I. Definitions of cephalometric variables

A-Nperp Linear distance from A-point to perpendicular toFrankfort plane through N

P-Nperp Linear distance from pogonion to perpendicular toFrankfort plane through N

Convexity Angle between NA line and AP lineSN.GoGn Angle between SN line and GoGn planeMx1.NA Angle between maxillary central incisor long axis

and NA lineMx1-NA Perpendicular distance between the labial surface of

the maxillary central incisor and NA lineMx1-PP Perpendicular distance between the incisal edge of

the maxillary central incisor and the palatal planeMx6-PP Perpendicular distance between the mesiobuccal

cusp of the maxillary first molar and the palatalplane

Md1.NB Angle between the mandibular central incisor longaxis and NB line

Md1-NB Linear distance from the labial surface of themandibular central incisor to NB line

Md1-GoMe Perpendicular distance between the incisal edge ofthe mandibular central incisor and the mandibularplane

Md5-GoMe Perpendicular distance between the buccal cusp ofthe mandibular second premolar and themandibular plane

IMPA Incisor-mandibular plane angleOverjet Distance from the incisal edge of the mandibular

incisor to the incisal edge of the maxillaryincisor, measured parallel to the functionalocclusal plane

Overbite Distance from the incisal edge of the mandibularincisor to the incisal edge of the maxillaryincisor, measured perpendicular to the functionalocclusal plane

Nasolabialangle

Angle between columella, subnasale, and labralesuperius

STconvexity

Angle formed between soft-tissue glabella,subnasale, and pogonion

Upper 1exposure

Distance between the incisal edge of the maxillarycentral incisor and the most inferior point on theupper lip

Upper lipto E

Linear distance from upper lip to E line (linebetween pronasale and soft-tissue pogonion)

Lower lipto E

Linear distance from lower lip to E line (linebetween pronasale and soft-tissue pogonion)

296 Janson et al

an implant (Figs 5-7).21,22 This increased the possibilityfor favorable bone formation in an ideal and stable sitefor future rehabilitation with an implant.23 Horizontaland vertical increases of the alveolar bone always occurwith tooth movement.24-26 Also, the number of replace-ment teeth would be increased with the procedure.

After the LeFort I osteotomy and fixation withtitanium miniplates, the remaining posterior open bitewas closed with vertical intermaxillary elastics, level-ing the occlusal plane by tooth extrusion.10,27,28 Theintermaxillary elastics were introduced immediatelyafter the surgical procedure and were used continuouslyfor 4 months until satisfactory and stable occlusal contactswere obtained. During this procedure, a 0.019 � 0.025-instainless steel rectangular archwire in the maxillaryarch and an 0.018-in round wire in the mandibular archwere used. The changes in the variable Mx6-PP con-firm the maxillary molar extrusion. However, there was

Table II. Pretreatment and posttreatment cephalometricstatus

Measurement Norm29-35 Pretreatment Posttreatment

Maxillary componentsSNA (°) 82 77.5 80.6A-Nperp (mm) 1 �3.5 �0.3

Mandibular componentsSNB (°) 80 82.2 83.5P-NPerp (mm) �2-4 6.8 11.0

Maxillomandibularrelationship

ANB (°) 2 �4.7 �2.9Convexity (NAP) (°) 3 �14.7 �12.5

Facial growth patternSN.GoGn (°) 32 27.7 25.2

Maxillary dentoalveolarcomponents

Mx1.NA (°) 22 33.9 35.1Mx1-NA (mm) 4 6.4 8.3Mx1-PP (mm) 30.3 24.8 26.1Mx6-PP (mm) 25.5 22.6 24.5

Mandibular dentoalveolarcomponents

Md1.NB (°) 25 6.5 18.2Md1-NB (mm) 4 �1.4 0.4Md1-GoMe (mm) 44.5 37.2 38.2Md5-GoMe (mm) — 28.1 25.9IMPA (°) 90 74.2 87.3Overjet (mm) 2.08 1.7 4.3Overbite (mm) 2.87 0.5 3.3

Soft-tissue componentsNasolabial angle (°) 110 85.7 75.6ST convexity (°) 12 �9.9 �7.3Upper 1 exposure

(mm)2 2.9 3.7

Upper lip to E (mm) �6 �8.9 �6.8Lower lip to E (mm) �4 �4.1 �2.4


mild reduction in the variable Md5-GoMe. It wasspeculated that this resulted from distalization andslight distal tipping of the premolars. The more theposterior teeth move distally, the closer the teeth are tothe mandibular plane (Table II).

A partial removable prosthesis was placed aftertreatment to rehabilitate the edentulous area (Fig 8).This treatment option was chosen because of insuffi-cient bone in the posterior area of the mandible, acontraindication for implant placement.

CONCLUSIONS

This case report demonstrates that surgical optionscan be satisfactory in patients with Down syndrome.They can be excellent orthodontic patients. The orth-odontic-surgical protocol provided good maxillary in-cisor exposure and excellent functional occlusion, andimproved the patient’s midface retrusion. Rehabilita-tion with a removable prosthesis showed that treatmenthad realistic rather than idealistic objectives.

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orthognathic treatment for a patient with class iii …...class iii malocclusion and surgically...

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