Distraction Osteogenesis

CASE REPORT

Unilateral Brodie bite treated with distractionosteogenesisJohn W. King, DDS, MS,a and James C. Wallace, DDSb

Midlothian, Va

Mandibular widening by distraction osteogenesis has recently been shown to be a very predictable,successful, and stable procedure with limited morbidity. One indication for mandibular widening bydistraction osteogenesis is a Brodie bite (scissors or buccal crossbite). This case report demonstrates atechnique used to treat a 12-year-old girl with a true unilateral buccal crossbite (no functional shift). It detailshow distraction osteogenesis can successfully treat unilateral problems with a distractor, a splint, andelastics. Details on this treatment technique have not been previously published. (Am J Orthod DentofacialOrthop 2004;125:500-9)

Transverse mandibular deficiency has been adifficult problem for orthodontists. Tradition-ally, it has been treated with extractions, dental

arch compensations, or orthognathic surgery. The trans-verse mandibular deficiency might manifest itself in aunilateral or bilateral buccal crossbite (Brodie bite).This Brodie bite occurs in 1.0% to 1.5% of thepopulation.1 During the past 15 years, distraction os-teogenesis has been gaining popularity as a treatmentmodality to correct many skeletal problems.2-5 Whenthis technique is used to correct the mandibular trans-verse problem, a midsymphyseal osteotomy is per-formed followed by gradual stretching the callus. In1990, Guerrero6 reported successful mandibular widen-ing by distraction osteogenesis with a tooth-bornedistractor in 10 patients. These techniques were subse-quently described in Bell’s textbook.7

This case report describes the treatment of a patientwith a true unilateral Brodie bite. Guerrero et al8

recommended treating unilateral “scissors bite” with aparasymphyseal osteotomy on the ipsilateral side. Le-gan9 suggested using cross-arch elastics in patients withasymmetry to increase or inhibit expansion. However,details of a thorough case report are lacking. Thepatient in this report was treated with distractionosteogenesis that included a custom-made hybrid dis-tractor.

aPrivate practice.bPrivate practice of oral and maxillofacial surgery.Reprint requests to: Dr John W. King, 5921 Harbour Ln, Suite 300, Midlothian,VA 23112; e-mail, [email protected], March 2003; revised and accepted, July 2003.0889-5406/$30.00Copyright © 2004 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2003.07.005

500

CASE PRESENTATIONDiagnosis

A girl, aged 11 years 10 months, was referred byher general dentist for evaluation of her posteriorbuccal crossbite. Her mother reported that she hadreceived regular dental care and had no oral habits.Although the patient had the sickle cell anemia trait,she was in excellent physical and dental health. Pre-treatment facial photographs showed a convex profile,mildly protrusive lips, and facial symmetry with com-petent lips (Fig 1). The maxillary dental midline was1.0 mm to the left of the facial midline; the mandibulardental midline was 1.6 mm to the left of the facialmidline. The patient had a Class I malocclusion, 3 mmof overjet, a 75% overbite, and a mild curve of Spee.Both the maxillary and the mandibular arches weresymmetrical, with 7.0 mm of maxillary arch lengthexcess and 5.4 mm of mandibular arch length excess(Figs 2-6). A left posterior buccal crossbite was present,without any lateral shift detected between centric rela-tion and centric occlusion (Fig 3). To confirm thisunilateral position, a full-coverage maxillary splint wasconstructed. One week after delivery of this appliance,study models were mounted in centric relation.

The panoramic radiograph showed a complete per-manent dentition, with erupting second molars andimpacted third molars. Although the patient’s profilewas convex and her lips were full, the lateral cephalo-metric radiograph indicated that the maxillary andmandibular incisors were in upright positions in theirrespective apical bases and that there was a moderateskeletal Class II discrepancy with an ANB angle of 7°.With a Frankfort-mandibular plane angle (FMA) of36.5°, the patient demonstrated a hyperdivergent skel-etal pattern. Despite evidence of a significant airway

Fig 1. Pretreatment fac

Fig 2. Pretreatment intra

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 125, Number 4

King and Wallace 501

deficiency and enlarged adenoids, there was no clinicalevidence of mouth breathing.

Fig 3. Unilateral Brodie bite.

The anteroposterior cephalometric radiograph andtracing showed a normal maxilla, as measured by interju-gale distance (J-J) (Table I). There was a severe mandib-ular transverse deficiency as measured at biantigonion(AGo-AGo). This maxillomandibular relationship seemedto be the primary underlying cause of the Brodie bite.

Etiology

Although mild lingual tipping of the mandibularposterior teeth contributed to the crossbite, the primaryproblem was the maxillary and the mandibular trans-verse width discrepancy. This skeletal transverse prob-lem was most likely genetic in origin.

ial photographs.

oral photographs.

American Journal of Orthodontics and Dentofacial OrthopedicsApril 2004

502 King and Wallace

Fig 4. Pretreatment dental models.Fig 5. A, Pretreatment panoramic radiograph; B, pre-treatment lateral cephalometric radiograph.Fig 6. Pretreatment anteroposterior cephalometrictracing.

traction; T4, posttreatment.



Treatment objectives

The main objective in treating this malocclusionwas to correct the left-side posterior buccal crossbiteand establish occlusal interdigitation. Because the pa-tient’s smile was attractive and the maxillary width wasnormal, we would attempt to maintain this width. Theoverbite and overjet would be reduced to an idealrelationship. Interdental spacing—the patient’s chiefcomplaint—would be eliminated. Although the maxil-lary and mandibular incisors were in acceptable posi-tions, some uprighting would be needed to eliminatethe arch length excess. Because the patient possessed a

Table I. Mandibular and maxillary arch widths from T

T1 T2 T3 T4 Ch

Mandibular33-43 26.75 27.67 33.93 26.4134-44 27.79 31.24 35.72 29.4235-45 36.11 36.69 40.75 35.336-46 39.1 39.34 41.93 40.1737-47 N/A N/A N/A 47.43

Maxillary13-23 36.8 41.28 40.88 34.9814-24 38.6 42.12 41.6 37.2315-25 45 46.54 45.98 42.1316-26 52.7 49.11 48.74 46.8917-27 N/A N/A N/A 53.55

FDI tooth numbers; T1, pretreatment; T2, predistraction; T3, postdis

Fig 7. Predistraction unilateral Brodie bite.

Fig 8. Bracket angulations on mandibular central inci-sors.

convex profile and full lips, this movement would notbe detrimental to her appearance.

Treatment alternatives

The first treatment option was to use intermaxillarycrossbite elastics to tip the mandibular left posteriorteeth labially and the maxillary left posterior teethlingually. This would effectively correct the posteriorbuccal crossbite. In addition, it would help reduce someof the maxillary arch length excess. Because the diag-nosis indicated the crossbite was primarily a skeletalproblem, long-term stability was a concern. In addition,lingual tipping of the maxillary left posterior teethmight alter the pleasing pretreatment smile.

The second option was to place a Hyrax expander inan “open” position, to produce palatal constriction andnarrow the maxilla bilaterally. This technique would

1 to T4 (mm)

ange T1-T2 Change T2-T3 Change T3-T4 Change T1-T4

0.92 6.04 �7.52 �0.342.24 4.48 �6.3 1.630.58 4.06 �5.45 �0.810.24 2.59 �1.76 1.07

4.48 �0.4 �5.9 �1.823.49 �0.52 �4.37 �1.41.58 �0.56 �3.85 �2.83

�3.61 �0.37 �1.85 �5.83

Fig 9. Presurgical radiograph reveals root divergence.



correct the left buccal crossbite but might also create aright posterior crossbite. Also, there was some concernabout changing the preexisting broad smile.

The third option involved closing the mandibularinterdental spacing and maintaining the mandibular inter-canine and intermolar widths. A maxillary segmentalosteotomy could be used to correct the crossbite.

The fourth option involved maintaining the maxillarywidth and closing the interdental spaces. The left posteriorbuccal crossbite would be corrected through mandibularwidening by midsymphyseal distraction osteogenesis. Be-cause the buccal crossbite was a true unilateral problem,the widening would have to be primarily on the left sidewhile the right occlusion was maintained.

The patient and her mother selected the fourthoption, which targeted the primary orthodontic problem(the mandibular transverse deficiency). If the rightposterior occlusion could be maintained, this treatmentoption would provide the best combination of occlusalfunction, optimal esthetics, and long-term stability.

Treatment progress

Preadjusted appliances (.018 � .022 in) wereplaced in the maxillary arch for leveling and alignment.Three months later, a biteplate was constructed, and the

Fig 10. Distraction splint. A, Right side with deon articulated study models. C, Left side with

Fig 11. Hybrid distraction appliance (tooth-borne andbone-borne).

mandibular appliances (Fig 7) were placed. Because themidsymphyseal osteotomy would be made between themandibular central incisors, the orthodontic bracketswere angulated (Fig 8). The resulting root divergence(Fig 9) reduced the chance of root and periodontalligament damage.10-12 A “figure 8” .014-in ligaturewire was placed on each side of the osteotomy site,connecting the central incisor, the lateral incisor, and thecanine to prevent “walking teeth” during the distractionperiod.13 During the predistraction phase of orthodontics,no attempt was made to either expand or contract thearches or to correct the patient’s buccal crossbite. A .016� .022-in stainless-steel arch wire was placed before theosteotomy. The archwire was cut at the osteotomy site atthe initiation of distraction. This provided segmentalanchorage during the distraction phase.

Before the midsymphyseal osteotomy, a full-coveragemaxillary splint (Fig 10) was constructed on an articulatorthat was mounted in centric relation. The splint wasmodified by creating a deep intercuspation on the man-dibular right side and a flat plane occlusion on the left.This stabilized the occlusion on the right side and allowedfor transverse widening on the left. Before surgery,crimp-on surgical hooks were placed in both archesbetween the brackets on the patient’s right side. A hybriddistractor (bone-borne and tooth-borne) (Fig 11) wasconstructed before the midsymphyseal osteotomy.

The midsymphyseal osteotomy was performed asdescribed by Conley and Legan.14 During the 7-daylatency period, the patient was prescribed antibioticsand used a .012% chlorhexidine rinse. After the latencyperiod, she returned to our office, and we initiateddistraction by making 0.5-mm turns twice per day, 1 inthe morning and 1 at night. During the distractionperiod, the patient was instructed to wear the maxillarysplint and right-side intermaxillary elastics full time,except for eating and brushing. Distraction was stoppedwhen the canines were in an ideal transverse relation-ship and the buccal crossbite was corrected (Fig 12, A).The total distraction, measured by the distraction screw

ep maxillary and mandibular interdigitation. B, Splintflat mandibular plane.

Fig 13. Four weeks postdistraction. A, Occlusal radiograph; B, periapical.



expansion, was 6.0 mm. A denture tooth was placed inthe distraction site on an anterior segmental archwirefrom the right lateral incisor to the left lateral incisor(Fig 12, B). This tooth was placed for cosmetic pur-poses and to prevent premature movement of theadjacent teeth. Crimp-on surgical hooks were added onthe patient’s left side, and she was instructed to discon-tinue using the splint. She wore bilateral intermaxillaryelastics full time for an additional week and then justwhile at home through the consolidation period. A softdiet was prescribed for 4 weeks. Periapical radiographswere taken every 4 weeks during the consolidationperiod to monitor the osteogenesis (Fig 13). During the10-week consolidation period, no tooth movement wasattempted.

At the end of the consolidation period, the distractorwas removed. The removal was performed in the oralsurgeon’s office with the patient under local anesthesia.Bony bridging was observed before removal.

When the mandibular central incisor brackets hadbeen repositioned and the roots realigned, space closureproceeded with stainless steel wires and sliding me-chanics. Power chains were used to close the distractionspace. Once the distraction was completed and thearches were coordinated, no attempt was made to eitherexpand or contract the arches. The maxillary andmandibular dental midlines were aligned with thepatient’s facial midline. Throughout the entire treat-ment, the patient was extremely cooperative.

The orthodontic appliances were removed after 26months of active treatment. Removable Hawley retain-ers were constructed for the patient and delivered 1week after appliance removal.

Treatment results

The Brodie bite was successfully corrected, and theexcellent right posterior occlusion was maintained(Figs 14-18). At the end of treatment, the shift from

Fig 12. A, End of distraction period with good canine relationship and 6-mm distraction space. B,Prosthetic tooth placed during consolidation period.

ent fa

nt intr



centric relation to centric occlusion was less than 0.5mm; this was verified through bilateral manipulation.

During the mandibular distraction osteogenesis,significant widening occurred, from 6.04 mm at theintercanine position to 2.59 mm at the intermolarposition (Table I). This coincided with a basal boneexpansion of 5.42 mm, as measured at the distractorbone screws (Table II). This compares favorably to thedistractor body expansion of 6.05 mm. Thus, there wasnearly parallel distraction of the skeletal and dentalcomponents, as measured on the dental casts and theanteroposterior cephalometric radiograph (Table III).

Mandibular symphyseal distraction with the hybrid

Fig 14. Posttreatm

Fig 15. Posttreatme

distractor produced a greater transverse increase in theanterior part of the arch than in the posterior. Duringthe postdistraction phase of orthodontic treatment, themandibular interdental arch dimensions were reducedto near predistraction amounts. This was apparently dueto space closure mechanics. As the mandibular poste-rior teeth moved mesially during the reciprocal spaceclosure, the intra-arch dimensions were reduced. In thefinal analysis, the intercanine distance decreasedslightly (�0.34 mm), whereas the intermolar widthincreased (1.07 mm). Thus, most of the Brodie bitecorrection was a result of a decrease in maxillaryintermolar width of 5.83 mm. As in the mandibular

cial photographs.

aoral photographs.

Fig 16. Posttreatment dental models.

treatment (red) tracings.



arch, this reduction occurred during space-closure me-chanics in the postdistraction orthodontic phase.

Although maxillary and mandibular intra-arch mea-surements decreased, the symphyseal bone markerswere shown to be very stable in the long term. Apostdistraction skeletal relapse of only 0.21 mm was

Fig 17. Postdistraction cephalometric radiographshowing parallel distraction of basal and alveolar bone.

Fig 18. Superimposed pretreatment (black) and post-

Go, Gonion; AGo, antigonion; J, jugale point.

SN, Sella-nasion line; Go, gonion; Gn, gnathion; LAFH, lower anterior facial height; NA, nasion-A-point line; NB, nasion-B-point line.



observed after 1.5 years. Thus, it seems that thenarrowing in mandibular intra-arch width was a resultof dental movement, not skeletal relapse.

Although the patient had a decrease in the maxillaryarch width, her broad smile was not compromised (Fig14). The maxillary dental midline was coincident withthe facial midline, and the mandibular dental midlinewas 0.5 mm to the right. Interdental spacing, thepatient’s chief complaint, was completely eliminated.Overjet was eliminated, and the overbite was correctedto approximately 50%.

Periodic examinations for temporomandibular dys-function (TMD) showed that the patient had an acute

symptom of clicking 1 month and 3 months postdis-traction. This symptom disappeared when the distractorwas removed and the occlusion was stabilized. Therewere no signs or symptoms of TMD at 6 months or 1year postdistraction.

Both the maxillary and the mandibular incisors wereuprighted during treatment. The maxillary incisor inclina-tion was reduced from a pretreatment angle (maxillarycentral incisor to sella-nasion line) of 98° to a posttreat-ment angle of 93° (Table IV). The mandibular incisorinclination was also reduced from a pretreatment angle(mandibular central incisor to gonion-gnathion line) of86° to a posttreatment angle of 78°. The uprighting of the

Table II. Skeletal measurements of distractor bone screws and bone markers (mm)

Skeletal markers T2 T3 3 mo 6 mo 1 y 1.5 y

Bone markers Hidden behind distractor Hidden behind distractor 15.03 14.62 14.66 14.82Distractor screws 9.54 14.96 N/A N/A N/A N/A

Table III. Anteroposterior cephalometric summary (mm)

Area of study T1 T2 T3 T4ChangeT1-T2

ChangeT2-T3

ChangeT3-T4

ChangeT1-T4

Bigonion (Go-Go) 99.37 99.99 100.37 99.16 0.62 0.38 �1.21 �0.21Biantigonion (AGo-AGo) 89.52 91.26 91.74 91.42 1.74 0.48 �0.32 1.9Biconcodylar 134.74 137.69 137.78 137.98 2.95 0.09 0.2 3.24Bone markers * * 14.82Distractor screws 9.54 14.96 5.42Interincisor apices 4.46 7.69 13.28 5.33 3.23 5.59 �7.95 0.87Intercanines 30.73 31.77 37.94 32.72 1.04 6.17 �5.22 1.99Inter-second molars 69.84 66.05 68.87 66.87 �3.79 2.82 �2 �2.97Maxillary width (J-J) 72.7 71.4 72.1 71.6 �1.3 0.7 �0.5 �1.1

*Hidden behind distractor.

Table IV. Lateral cephalometric summary

Area of study Measurement T1 T2 T3 T4ChangeT1-T2

ChangeT2-T3

ChangeT3-T4

ChangeT1-T4

Maxilla to cranial base SNA angle (°) 84.5 83.5 85 85.5 �1 1.5 0.5 1Mandible to cranial base SNB angle (°) 77 76 77.5 77.5 �1 1.5 0 0.5

SN-Go-Gn (°) 48 50.5 50 50 2.5 �0.5 0 2FMA angle (°) 36.5 37.5 38 38.5 1 0.5 0.5 2

LAFH (%) 55.70 53.7 56.2 56.2 �2 2.5 0 0.5Maxillomandibular ANB angle (°) 7.5 7.5 7.5 8 0 0 0.5 0.5Maxillary dentition 1 to NA (mm) 1 1 1.5 �1.5 0 0.5 �3 �2.5

1 to NA (°) 14 15 15.5 7.5 1 0.5 �8 �6.51 to SN (°) 98 99 101 93 1 2 �8 �5

Mandibular dentition 1 to NB (mm) 11.5 11 11 8.5 �0.5 0 �2.5 �31 to NB (°) 30 29.5 32 24 �0.5 2.5 �8 �6

1 to Go-Gn (°) 86 82 86 78 �4 4 �8 �8Soft tissues Esthetic plane (mm) 3.5 1 0 1 �2.5 �1 1 �2.5



incisors, along with mandibular growth at pogonion,produced a less convex profile. This uprighting alsoresulted in a reduction of lip fullness.

Although the patient was hyperdivergent with asteep mandibular plane angle, there was only a mildincrease in her mandibular plane angle (FMA pretreat-ment to posttreatment � 2°). Most of this increaseoccurred during the predistraction and postdistractionorthodontic phases. Thus, the distraction phase itselfhad only a minimal effect on this clockwise rotation(FMA predistraction to postdistraction �.5°).

DISCUSSIONAs with many other problems in orthodontics,

clinicians are faced with the dilemma of either treatingthe skeletal problem or resorting to dental compensa-tions. A true unilateral Brodie bite is relatively rare.1

Until recently, a mandibular transverse deficiency wasalmost always treated with dental compensations. How-ever, research has shown an inherent instability whenintercanine width is expanded.15-17 Similarly, severalarticles have shown that intermolar width might also beunstable if expanded during orthodontic treatment.18,19

Now, with the advent of distraction osteogenesis, atransverse skeletal deficiency can be treated with man-dibular widening.

The case reported here is unique because it involved2 questions: can mandibular widening be performedunilaterally? And, if so, would such widening createacute or chronic TMD problems? Treating this patientwith a dental compensation option might have compro-mised her broad, attractive smile. Also, questions con-cerning the long-term stability of mandibular dentalexpansion have been presented.

Various dental and skeletal measurements on theradiographs and dental casts demonstrate a nearly paralleldistraction of the skeletal basal bone to the alveolar bone.A near-parallel opening can also be observed on thepatient’s cephalometric radiograph (Fig 17). Thus, theteeth and alveolus are supported by the basal bone.Expanding basal bone proportionally to alveolar bone isexpected to provide increased stability.12,14,20-22

CONCLUSIONS

Mandibular widening by distraction osteogenesisoffers a new treatment option for the contemporaryorthodontist. The treatment of this patient with distrac-tion osteogenesis was minimally invasive, comfortable,predictable, and affordable.

REFERENCES

1. Harper DL. A case report of a Brodie bite. Am J OrthodDentofacial Orthop 1995;108:201-6.

2. Figueroa AA, Polley JW, Ko E. Distraction osteogenesis fortreatment of severe cleft maxillary deficiency with the REDtechnique. In: Samchukov ML, Cope JB, Cherkashin AM,editors. Craniofacial distraction osteogenesis. St. Louis: Mosby;2001. 485-93.

3. McCarthy JG, Schreiber J, Karp N, Thorne CH, Grayson BH.Lengthening the human mandible by gradual distraction. PlastReconstr Surg 1992;89:1-10.

4. Chin M. Distraction osteogenesis for dental implants. In: Stucki-McCormick SU, editor. Atlas of the oral and maxillofacialsurgery clinics of North America. Philadelphia: WB Saunders;1999. 41-63.

5. Stucki-McCormick SU. The effect of distraction on the temporo-mandibular joint. In: McCarthy JG, editor. Distraction of thecraniofacial skeleton. New York: Springer-Verlag; 1999. 249-71.

6. Guerrero CA. Expansion mandibular quirurgica. Rev VenezOrtod 1990;1:48-50.

7. Guerrero CA, Contasti GI. Transverse mandibular deficiency. In:Bell WH, editor. Modern practice in orthognathic and recon-structive surgery. Vol. 3. Philadelphia: WB Saunders; 1992.2383-97.

8. Guererro CA, Bell WH, Contasti GI, Rodriguez AM. Mandibularwidening by intraoral distraction osteogenesis. Br J Oral Maxil-lofac Surg 1997;35:383-92.

9. Legan HL. Orthodontic planning and biomechanics for trans-verse distraction osteogenesis. Semin Orthod 2001;7:160-8.

10. Guerrero CA, Bell WH, Contasti GI, Rodriguez AM. Intraoralmandibular distraction osteogenesis. Semin Orthod 1999;5:35-40.

11. Bell WH, Harper RP, Gonzalez M, Cherkashin AM, SamchukovML. Distraction osteogenesis to widen the mandible. Br J OralMaxillofac Surg 1997;35:11-9.

12. Del Santo M, English JD, Wolford LM, Gandini LG. Midsym-physeal distraction osteogenesis for correcting transverse man-dibular discrepancies. Am J Orthod Dentofacial Orthop 2002;121:629-38.

13. Contasti G, Guerrero C, Rodriguez AM, Legan HL. Mandibularwidening by distraction osteogenesis. J Clin Orthod 2001;35:165-73.

14. Conley R, Legan H. Mandibular symphyseal distraction osteo-genesis: diagnosis and treatment planning considerations. AngleOrthod 2003;73:3-11.

15. Little RM, Wallen T, Riedel R. Stability and relapse of mandibularanterior alignment—first premolar extraction cases treated by tradi-tional edgewise orthodontics. Am J Orthod 1981;80:349-65.

16. Shapiro PA. Mandibular dental arch form and dimension. Am JOrthod 1974;66:58-70.

17. Burke SP, Silveira AM, Goldsmith LJ, Yancey JM, Stewart A,Scarfe WC. A meta-analysis of mandibular intercanine width intreatment and post retention. Angle Orthod 1998;68:53-60.

18. Riedel RA. A review of the retention problem. Angle Orthod1960;30:179-99.

19. Sinclair PM, Little RM. Maturation of untreated normal occlu-sions. Am J Orthod 1983;83:114-23.

20. Del Santo M, Guerrero CA, Buschang PG, English JD, Sam-chukov ML, Bell WH. Long-term skeletal and dental effects ofmandibular symphyseal distraction osteogenesis. Am J OrthodDentofacial Orthop 2000;118:485-93.

21. Mommaerts MY. Bone anchored intraoral device for transman-dibular distraction. Br J Oral Maxillofac Surg 2001;39:8-12.

22. Guerrero CA, Bell WH, Gonzalez M, Meza LS. Intraoraldistraction osteogenesis. In: Fonseca RJ, editor. Oral and max-illofacial surgery. Philadelphia: WB Saunders; 2000. 359-415.

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