correction of facial asymmetry as a result of unilateral condylar hyperplasia

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J Oral Maxillofac Surg70:1413-1425, 2012

Correction of Facial Asymmetry as aResult of Unilateral Condylar Hyperplasia

Robert Hillary Boucaut Jones, BDS, BSc(Dent), MDS, FRACDS, FRACDS(OMS),*

and Graham A. Tier, BDS, FDSRCPS(Glas), FRACDS, FRACDS(OMS)†

A mild degree of facial asymmetry is normal, and oneonly has to mirror the 2 separate sides of the face andcompare the contours of the left side of the face withthe right, to find that the images will be completelydifferent. However, if this mild disparity becomesmarkedly obvious, then individuals will seek treat-ment for the problem.

The common causes of facial asymmetry includethe following:

1. Craniosynostosis affecting the base of the skull,eg, Apert’s syndrome (Fig 1A)

2. Craniofacial clefting (Fig 1B)3. Hemifacial microsomia4. Trauma to the mandibular condylar growth cen-

ter5. Condylar hyperplasia6. Hemimandibular hyperplasia7. Hemimandibular elongation8. Tumors benign or malignant

Obwegeser and Makek1 discussed the commoncauses of mandibular asymmetry, with particular em-phasis on those relating to an increase in the activityof the condylar growth centers on 1 side or the other.These they referred to as hemimandibular elongationand hemimandibular hyperplasia.

Wolford et al,2 in a more recent article, take this astep further and have simplified the classification.They consider condylar hyperplasia to be a patholog-ical condition that induces overdevelopment of thecondylar head, neck, or mandible generally and can

*Professor, Townsville Hospital, James Cook University, Institute

of Surgery, Douglas, Townsville, Queensland, Australia.

†Consultant Oral and Maxillofacial Surgeon, Prince of Wales

Hospital, Sydney, New South Wales, Australia; Senior Lecturer,

University of New South Wales, Sydney, New South Wales,

Australia.

Address correspondence and reprint requests to Dr Boucaut

Jones: Townsville Hospital, James Cook University, Institute of

Surgery, 100 Douglas Smith Dr, Douglas, Townsville, Queensland

4813, Australia; e-mail: [email protected]

© 2012 American Association of Oral and Maxillofacial Surgeons

278-2391/12/7006-0$36.00/0

oi:10.1016/j.joms.2011.03.047

1413

be caused by several different pathological entities,each of which will have a different effect on the facialskeleton. The bilateral form will produce a symmetri-cal mandibular hyperplasia that progresses beyondthe normal parameters of growth, and if there is adifferential growth anomaly, with 1 side growingmore than the other, an asymmetry will develop,which is usually progressive. This form of condylarhyperplasia is the same as Obwegeser’s hemifacialelongation, which may be symmetrical or asymmetri-cal. Wolford refers to the symmetrical form as CH 1A(bilateral symmetrical form) and CH 1B (asymmetricalform). He refers to the unilateral enlargement of thecondylar head, neck, ramus, and body of the mandibleas CH 2, which is the same as that described byObwegeser as hemimandibular hyperplasia.

Therefore,

CH 1A Bilateral, symmetrical, condylar hyperplasiaCH 1B Unilateral, asymmetrical, condylar hyperplasiaCH 2 Unilateral, asymmetrical, condylar hyperplasia

(hemimandibular hyperplasia)

Each of these conditions has its own particular facialappearance, and correction is aimed at the affectedparts of the facial skeleton and the soft tissues in-volved.

The common thread is an overactivity of the con-dylar growth center, and the nature of this will deter-mine the method and timing of the surgery.

Hemimandibular elongation, or CH 1B (Fig 2), willcharacteristically show an elongated condylar neck,thinning of the vertical ramus and body of the man-dible, and significant deviation of the chin away fromthe side of the overgrowth. The lower incisors willoften be tilted toward the active condyle, with theirapices lining up with the midpoint of the chin and theincisal edges close to the midsagittal plane. There isalso canting of the occlusal plane away from theaffected side, as the maxillary alveolus compensatesfor the abnormal mandibular growth. If there is anincrease in activity of the condylar growth centerbeyond that of the compensatory growth of the max-illary alveolus, there will be a lateral open bite.

There will also be a 3-dimensional alteration ofnormal chin anatomy, which will need to be ad-
dressed at the time of surgery.
mailto:[email protected]

1414 CORRECTION OF FACIAL ASYMMETRY FOR UNILATERAL CONDYLAR HYPERPLASIA

For hemimandibular hyperplasia or CH 2 (Fig 3),the mandibular condyle and neck are enlarged, alongwith the vertical ramus and body of the mandible onthe affected side. There is often a distinctive bowingof the body of the mandible that stops at the midline.There is also compensatory growth of the maxillaryalveolus on the affected side producing a cant of theocclusal plane. The activity of the condylar growthcenter will determine the nature of the cant. If the

FIGURE 1. Facial asymmetry caused by Apert’s syndrome (A),and a facial cleft (B).

Jones and Tier. Correction of Facial Asymmetry for UnilateralCondylar Hyperplasia. J Oral Maxillofac Surg 2012.

condyle is slowly growing, the compensatory changes

along with the cant may be significant, but if theactivity of the condyle is high, an open bite willdevelop, as the compensatory changes in the alveolusof the maxilla will not be able to keep pace with thegrowth of the mandible. As in the previous example,there will also be a 3-dimensional alteration of thechin.

If an osteochondroma is the cause of the asymme-try (Fig 4), a similar facial appearance will occur butthe architecture and shape of the mandibular condylewill be different. The condyle will be abnormal inappearance and may be multilocular in size andshape.

This article is a retrospective article that deals withthe diagnosis, assessment, and treatment of facialasymmetry, arising from a consecutive series of pa-tients with the various combinations of unilateral con-dylar hyperplasia (CH 1B or CH 2).

Materials and Methods

Seventeen consecutive patients in this retrospec-tive series were treated for facial asymmetry arisingfrom unilateral condylar hyperplasia (CH 1B or CH 2)and are presented in tabular form. All patients under-went the same investigations to determine a diagno-sis, and all patients were investigated for overactivityof the affected growth center using Tc-99 bone scans(Tc-99 methylene diphosphonate [MDP] with single-photon emission computed tomography [SPECT]), se-rial models, photographs, cepahalometric radio-graphs, and tracings. Ethics approval for this studywas granted by the Townsville Health Services Dis-trict Human Research Ethics Committee.

Those patients who showed continuing activitywithin the affected joint over a period of 12 monthswere offered condylectomy as part of the operativeprocedure to shut down the growth center and pre-vent ongoing asymmetry of the face. Most of the casesincluded in this study fell into this category.

ASSESSMENT

The assessment process aims to achieve a balancebetween the definition of the problem, as perceivedby both the surgeon and the patient, and the need toaddress the discrepancy at the source of the problemwithout camouflaging it. First, accurate photographsof the face and of the occlusion are taken, followed byradiographs, including lateral and posterior anterior(PA) cephalometric projections, and finally, studymodels, set up on an anatomical articulator. Combin-ing the data thus obtained, the overall deformity canbe diagnosed and an accurate treatment plan formu-lated, particularly with respect to the amount of bone
removal required to correct the occlusal cant. It is

JONES AND TIER 1415

FIGURE 2. Hemimandibular elongation. Note cant of the occlusal plane (A) (CH 1B), elongation of the condylar neck (B), and lengtheningof the right side of the face, producing the asymmetry (C).

Jones and Tier. Correction of Facial Asymmetry for Unilateral Condylar Hyperplasia. J Oral Maxillofac Surg 2012.

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FIGURE 3. Hemimandibular hyperplasia (A). Note the cant of the occlusal plane (B), and bowing of the mandibular body (C) (CH 2), andlso the increase in activity of the mandibular condyle on Tc-99 bone scan (D).

ones and Tier. Correction of Facial Asymmetry for Unilateral Condylar Hyperplasia. J Oral Maxillofac Surg 2012.

JONES AND TIER 1417

FIGURE 4. Asymmetry because of osteochondroma of the mandibular condyle (CH 2). Preoperative photographs (A) lateral and (B) full face,(C) CT scan of the active condyle, (D) preoperative occlusion, (E) postoperative occlusion. Postoperative photographs, (F) lateral face and(Figure 4 continued on next page.)

Jones and Tier. Correction of Facial Asymmetry for Unilateral Condylar Hyperplasia. J Oral Maxillofac Surg 2012.

J ondyla


therefore necessary to remove the same amount ofbone from the mandibular condyle, to stop the activ-ity of the condylar growth center. In most cases, thiswill also align the angles of the mandible.

This process will give a diagnosis at the time of theinitial assessment, but condylar hyperplasia is a dy-namic problem, and time will also need to be factoredin. If ongoing growth in the affected mandibular con-dyle is suspected or confirmed, it will be necessary torepeat the process at a later date, and compare the 2sets of records. A bone scan (Tc-99 MDP with SPECT)will also be required in both instances, to determinethe activity of the condylar growth center.

This scan compares the activity of the affectedside with that of the normal side, and if necessary,with that of another growth center. Unfortunately,this may be subject to some inaccuracy, as theaffected condyle may be subject to either an inflam-matory process or the normal physiological growthstimulus of early adolescence, yielding a false pos-itive result.

Furthermore, this scan is a static assessment andonly indicative of the activity of the condylar growthcenter at the time it is taken, necessitating furtherfuture scans to determine if the joint was still active.

However, if all the information, photographs, studymodels’ radiographs, and bone scans are correlatedover time, some indication of the activity can bemade.

TREATMENT

The treatment is carried out in the 4 following

FIGURE 4 (cont’d). (G) full face, (H) po

ones and Tier. Correction of Facial Asymmetry for Unilateral C

phases:

1. Orthodontics to align and decompensate thedentition

2. Surgery to correct the problem and restore thefacial midlines

3. Orthodontics to complete and correct the occlu-sion

4. Attention to the soft tissues will often be re-quired either to remove any excess tissues onthe expanded side or to increase the bulk oftissues on the nonaffected side. This can beachieved by the placement of an implant onthe lateral aspect of the mandible on the non-affected side, which will both bulk out the softtissues and augment the mandible. However,this will be patient dependent, determined bytheir esthetic desires and which side of theface they prefer after the skeletal correction.

The surgical phase of treatment is dependent on theaccurate assessment of the activity of the condylargrowth center. If the growth center activity hasceased, the correction can be made without involve-ment of the previously affected condyle (Fig 5). How-ever, if the condyle is continuing to grow and theasymmetry becoming worse, consideration to shutthe growth center down should be made, and if not,the decision should be to wait until the growth hasceased.

The problem with waiting until growth has ceasedis its unpredictability, and how much further asym-metry will develop before it ceases. In such a case, the

ative lateral CT with costochondral graft.

r Hyperplasia. J Oral Maxillofac Surg 2012.

stoper

correction may require considerably more orthodon-

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JONES AND TIER 1419

tics and surgery (particularly of the soft tissues) if asatisfactory correction is to be achieved.

In general, the correction of facial asymmetryinvolves the maxilla, the mandible, the chin, andthe soft tissues. If there is an orbital component, itcan also be addressed at the same time with anintraoral zygomatic osteotomy.3 However, this isuncommon.

If the condyle is still active, a condylectomy will berequired, either at the same time as the jaw correctionor at another time, depending on the nature of the

FIGURE 5. Asymmetry where the condylar growth center was inocclusion (C), preoperative occlusion after preliminary orthodontic

Jones and Tier. Correction of Facial Asymmetry for Unilateral C

problem and the choice of the surgeon. It has been

found that at least 6 mm of the articular surfacerequires removal to shut the growth center down.2

Attention to disc position is important; therefore, anydisc displacement should be corrected at operationand the incidence of displacement should be reducedafter surgery. An anchor placed in the posterior as-pect of the mandibular condyle and attachment of thedisc to this anchor will address this problem andallow the disc to move more accurately with thecondyle during mandibular movement.4

It is advisable to remove the same amount of bone

(A), preoperative full face showing asymmetry (B), preoperativeostoperative result.


actives (D), p

from the condylar head as that removed from the

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maxilla on the affected side. This will correct the oc-clusal cant and bring the angle of the mandibleclose to that of the nonaffected side, thereby correct-ing the asymmetry of the mandibular angles.

Bilateral sagittal split osteotomies are then per-formed to bring the teeth to the midline and close thelateral open bite on the affected side.

This will correspond to the same amount of boneremoved from the maxilla and the condylar head. Inthis instance, the splaying of the proximal segment ofthe sagittal split on the nonaffected side will providesome of the contour correction, but will need a graftbetween the halves of the sagittal split, to hold thesegments in place, and reduce torque of the condylarhead.5

After the mandible and maxilla have been fixed, thechin can be corrected with a genioplasty. In mostinstances, this will be a complex 3-dimensional genio-plasty, where bone will be removed from 1 side in thevertical direction, to move it across to the midline,and set it back or advance it, depending on the natureof the problem.

Once the surgery has been completed and stabi-lized, the orthodontics can be completed. When theswelling has settled, an assessment of the soft tissuescan be made. The soft tissue surgery will requireeither a facelift on the affected side to remove excesstissue or an augmentation of the opposite side, eitherwith a “medpore” ramus/body implant or dermis fat,or fat graft to the soft tissues. However, this is agedependent, and the older patient in whom the asym-metry is significant will require this type of surgery,while the younger patient is more resilient.

If the asymmetry is diagnosed early, and it can bedetermined that the patient has an ongoing problem,early condylectomy and redirection of growth withfunctional appliance therapy and orthodontics canaddress the problem.

The girl in Figure 6, diagnosed with hemimandibu-lar hyperplasia (CH 1 B), as seen on the OPG andTc-99 bone scan at age 11 years, underwent highcondylectomy followed by functional appliance andorthodontics. Her postoperative result is seen at theage of 17 years in the last photograph.

Table 1 presents the cohort of consecutive patientsreferred to in this article and represents the demo-graphics and the diagnosis of the patients treated.

Results

Seventeen consecutive patients were treated forthe correction of facial asymmetry arising from unilat-eral condylar hyperplasia, and the results are pre-sented in Table 2. All patients underwent the sameinvestigations to determine the nature of the prob-
lem, and all patients were investigated with Tc-99
bone scans, serial models, photographs, cephalomet-ric radiographs, and tracings to determine the activityof the mandibular condyle and to formulate a treat-ment plan. Table 2 represents the results of the 17

atients treated in this study and outlines their diag-osis, treatment, and outcomes. Those patients whohowed continuing activity within the affected jointver a period of 12 months were offered condylec-omy as part of the operative procedure. This waserformed to shut down the growth center and stophe continuing growth of the mandible, thereby pre-enting further asymmetry of the face. Most patientsresented in this article were in this category.Some patients with hemimandibular hyperplasia

CH 2) underwent condylectomy with costochon-ral graft replacement (Fig 3). In these cases, there

s bowing of the lower border of the mandible,hich was corrected by removing the bowed seg-ent. This bone could then be onlayed to the

ateral aspect of the mandible to recontour it. Un-ortunately, this bone behaves as any onlay, and thenitial symmetry achieved is subject to change ashe bone remodels.

Most of the patients underwent the regimen ofemporomandibular joint (TMJ) surgery and disc re-osition at the same time as the corrective jaw sur-ery to the maxilla, mandible, and chin, with the samemount of bone removed from the maxilla as takenrom the condyle to restore symmetry.

Discussion

A degree of facial asymmetry is common in thecommunity, and those who require surgical correc-tion for a significant condition are few. This articlepresents 17 patients with facial asymmetry arisingfrom unilateral condylar hyperplasia, either as hemi-mandibular elongation (CH 1B) or as hemimandibularhyperplasia (CH 2). In each category a similar facialappearance can be shown, but each group will re-quire a different surgical procedure. Nonetheless, theprinciples of treatment are the same.

The various phases of treatment are as follows:

1. Orthodontics to align and decompensate theteeth.

2. Surgery to the maxilla, mandible, and chin, andwhere indicated; condylectomy of the affectedjoint to shut down the mandibular condylargrowth center.

3. Orthodontics to complete and refine the occlu-sion.

4. Attention to the soft tissues as required.

Condylectomy at the same time as orthognathic
surgery can make the operation technically diffi-

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JONES AND TIER 1421

cult, but approached in a systematic way, it is easilyachievable. It has been reported that the removal of6 mm6 from the condylar head is required to shutrowth down; however, if one removes the samemount of bone from the condyle as that requiredo correct the occlusal cant, total symmetry of theacial skeleton is the result. The authors prefer a

FIGURE 6. Hemimandibular hyperplasia corrected early with coshowing asymmetry. C, Posterior anterior cephalometric projec

Jones and Tier. Correction of Facial Asymmetry for Unilatera

ingle operation, as previously outlined. Some peo- o

le advocate a 2-stage approach, first to performondylectomy to shut the growth of the mandibleown, and once this has been determined, then toroceed to correct the asymmetry. A problem with-stage procedures is that many patients will notccept a second operation.

In the combined single procedure, the maxillary

tomy and functional therapy. A, Preoperative full face. B, OPGowing asymmetry. (Figure 6 continued on next page.)

ylar Hyperplasia. J Oral Maxillofac Surg 2012.

ndylection sh

steotomy is carried out first.

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The initial records are taken with the jaws in cen-tric relation with each condyle intact and centrallyplaced within the glenoid fossa. Therefore, the max-illa is set up on the articulator in the original position,using the original unoperated mandibular condyle (insome instances, this may be incorrect due to abnor-mal condylar or ear position). The maxilla is thenrepositioned, with correction of the occlusal cant andfixed using the intermediate wafer. This then acts as astable platform onto which to place the mandible

FIGURE 6 (cont’d). D, Tc-99 bone scan showing activ


after correction of the asymmetry.

The condylectomy is then performed, followedby sagittal osteotomy of the mandible, and the op-erated mandibular condyle can be seated underdirect vision. However, the face bow transfer inpatients with asymmetry can present a problem,because of the variable position of the ear or TMJ,and may be inaccurate. Wolford and Gatiano havepresented an article on a simplified and more accu-rate method of transferring the maxillary model tothe articulator, thereby eliminating an inaccurate

yle. E, Functional appliance in position. F, Final result.


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face bow transfer.7

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JONES AND TIER 1423

Once the mandible has been positioned and rigidlyfixed correctly, the genioplasty can be carried out.This may be complicated because of the need tocorrect the chin in 3 dimensions.

Before closure of the TMJ, it is necessary to ensurethe disc is in position, particularly if one is to avoidclicking and locking post surgery. This is best carriedout using a 2-mm “anchor” and attaching the disc tomandibular condyle4 or disc plication depending onurgical preference.

For hemimandibular hyperplasia (CH 2), or whenhe asymmetry has resulted from an osteochon-roma, it is often necessary to perform a completeondylectomy and reconstruct the joint with eithercostochondral rib graft (Fig 3) or a total joint

eplacement.Correction of the bowing of the lower border, in

ases of hemimandibular hyperplasia (CH 2), can bechieved by an intraoral approach, using a long sag-ttal split and then decorticating the mandible to the

ental foramen and releasing the inferior dentalerve from its canal. Then, the osteotomy of the

ower border can be completed through the inferiorental (ID) canal to the lingual side of the mandible,nd the lower border removed.8 The lower border

may then be adjusted by grinding to shape with alarge bone bur to achieve the symmetry required. Ifthere is a deficiency of mandibular width, the re-sected section of mandible can be fixed to the sideof the mandible, or rotated up onto the operatedside, to correct contour if needed. However, it

Table 1. PATIENT COHORT WITH DIAGNOSIS

Patient Gender Diagnosis

1 F HME (CH 1B)2 F HME (CH 1B)3 F HME (CH 1B)4 F HME (CH 1B)5 F HME (CH 1B)6 M Osteochondroma (CH2)7 F HME (CH 1B)8 F HME (CH 1B)9 F HME (CH 1B)

10 F HME (CH 1B)11 F HME (CH1B)12 M HMH (CH 2)13 F HMH (CH 2)14 F HME (CH 1B)15 F HMH (CH 2)16 F HME (CH 1B)17 F HME (CH 1B)

Abbreviations: HME, hemimandibular elongation (CH 1B);HMH, hemimandibular hyperplasia (CH 2); F, female pa-tient; M, male patient.

Jones and Tier. Correction of Facial Asymmetry for Unilateral
Condylar Hyperplasia. J Oral Maxillofac Surg 2012.
should be remembered that if this bone is onlayedto the lateral aspect of the mandible, it will mostlikely resorb over time, and further surgery may berequired to correct the problem. A 3-dimensionalgenioplasty will also be required to correct theasymmetry.

HISTOPATHOLOGY

In describing the normal histology of the mandib-ular condyle, Hansson et al9 have described 4 tissuelayers and have referred to them as

1. A connective tissue lining (fibrous articularlayer)

2. An undifferentiated mesenchyme (proliferating)layer

3. A transitional layer4. A hypertrophying cartilage layer

The total thickness of these layers is approximately0.48 mm in normal condyles.

In the original article by Obwegeser and Makek,1

discussion occurred about the histopathology asso-ciated with the overgrowth of the mandibular con-dyle. They indicated there was a thickened cartilagezone with a wide richly vascularized proliferativezone enriched with large cells near the bony as-pect, with osteoblasts surrounded by newly formedtrabeculae.

This new growth and the changed architecture ofthe condylar head and neck force the mandible togrow inferomedially. The classic histopathologicalslides as described above have continued; however,other authors have divided the histopathological pic-ture into several different subtypes10 and an article byslami et al11 has further subdivided some of the

samples into further subtypes. However, the overallconclusion is that the hyperplastic cartilage layer un-dergoes a significant increase in thickness in condylarhyperplasia, and that this increase in growth drivesthe asymmetry.

Another article that looked at the histopathology ofresected condylar heads from treated cases of condy-lar hyperplasia found the histopathological picturewas different, and they found little correlation be-tween the histopathological pictures seen and consid-erable variation.12 This correlates with a study carriedout some years before by one of the authors andpresented to the annual meeting of the Australian andNew Zealand Association of Oral and MaxillofacialSurgeons meeting in Christchurch, New Zealand,where it found that no specific histopathological pic-ture of the active joint was found, once again withconsiderable variation, albeit in a small number of
cases.

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BONE SCANS

Tc-99 bone scan uptake is specific for osteoblastsand the laying down of new bone, and as such, theTc-99 bone scan was thought to be an accurate indi-cation of activity within the condyle. The Tc-99 bonescan will show activity within the joint in condylarhyperplasia if new bone is being laid down, but thescan is very nonspecific. In an article by Saridin etal,13 quantitative analysis of planar scintigrams usingTc-99 hydroxymethylene diphosphonate (HDP) inunilateral condylar hyperplasia was not found to besuperior to qualitative visual interpretation of thescans, and that quantified ratios between the activecondyle and other growth centers did not seem tobe helpful; therefore, clinical assessment was thoughtto be mandatory.

The importance of time in this assessment has been

Table 2. RESULTS OF THE 17 PATIENTS TREATED IN THIAND OUTCOMES

Patient Diagnosis

1 HME (CH 1B) ConOrth





6 Osteochondroma (CH 2) ConCost






12 HMH (CH 2) ConOrth

13 HMH (CH 2) ConCostOrth


15 HMH (CH 2) ConCostOrth




stressed by Kaban,14 particularly in cases of hemifa- o

ial microsomia. However, time is also important withondylar hyperplasia when determining activity ofhe affected condyle and the timing of surgery.

Interestingly, in another article15 using SPECT,c-99 MDP, or MDP, SPECT was found to be moreccurate in determining the activity of the condylever planar scintigrams.In this article, isotope counts were found to be of

alue and were able to predict active growth fromrowth cessation. They concluded that condylar iso-ope deposits for each pair of condyles differing byess than 10% can be regarded as normal, and that anctivity of greater than 10% suggested that bonerowth was still active and that corrective surgeryhould be delayed or that interceptive surgery shoulde offered.There have been several articles discussing the use

DY AND THEIR DIAGNOSIS, TREATMENT,

Treatment Outcome

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

mydral graft and orthognathic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery removal lower border

Satisfactory

mydral grafthic surgery

Satisfactory

myhic surgery

Satisfactory

mydral grafthic surgery

Satisfactory

myhic surgery

Satisfactory

myhic surgery

Satisfactory


S STU

dylectoognatdylectoognatdylectoognatdylectoognatdylectoognatdylectoochondylectoognatdylectoognatdylectoognatdylectoognatdylectoognatdylectoognatdylectoochonognatdylectoognatdylectoochonognatdylectoognatdylectoognat

f Tc-99 bone scan with and without SPECT to deter-

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JONES AND TIER 1425

mine the activity of the affected condyle, but fewarticles have discussed and compared the histopatho-logical findings with the bone scan findings. Gray etal16,17 have looked at this correlation and discussedhe macro- and micromorphology, but little in relationo the correlation between this and the bone scans.ippold et al18 have discussed this aspect in someetail and have reported that activity of the affectedondyle on bone scan was associated with a typicalistopathological finding, that those condyles with aigh uptake of Tc-99 showed histopathological signsf destroyed cartilage, accompanied by a broadeningf the subcondylar layer of bone, and that this broadroliferating zone of bone was associated with anverlying layer of degenerative cartilage. The highissue turnover was characterized by resorption andeplacement, which caused bony areas to containslands of cartilage, and that by comparison, thoseondyles showing less activity showed fewer signs ofrthrosis. This pattern of bone turnover would fit inith an understanding of Tc-99 bone scan technol-gy, with the Tc-99 uptake relating to active areas ofone turnover and uptake by the osteoclasts andsteoblasts.According to Kruse-Losler et al,19 this cartilage de-

generation was also seen in distraction osteogenesisand that the active growth of the mandibular condylewith resultant pressures on the articulating surfacesmay be the cause of the degeneration.

Another interesting finding was the high number offemales in this group of patients, with similar figureshaving been reported elsewhere. It has been sug-gested that there are increased numbers of estrogenreceptors in the temporomandibular joint in females,which could account for this increased activity.20

The questions raised are as follows: 1) why thedifferentiation between condylar hyperplasia I and II,hemifacial elongation, and hemifacial hyperplasia; 2)

hat is the stimulus for the 2 different types of hy-erplasia; 3) why does the hyperplasia stop at theidline of the mandible.There would appear to be some sort of mediator

timulating the activity of the condyle, condylar neck,nd ramus of the mandible in the case of hemiman-ibular hyperplasia (CH 2), which is different fromhat stimulating hemimandibular elongation (CH 1And B). We do know that performing a condylectomy,lbeit high in hemimandibular elongation (CH 1 B)nd total in hemimandibular hyperplasia, will stop therowth of the mandible, and therefore, it would ap-ear that the effective stimulus is in the mandibularondyle near the articular surface. The only otherossibility is that there are 2 separate mechanisms
timulating the process, 1 in hemimandibular elonga-
tion (CH 1 and 1A) and another in hemimandibularhyperplasia (CH 2).

While the surgery to correct the problem is rela-tively straightforward, there are many questions thatneed to be answered before we have a total under-standing of this interesting clinical problem.

References1. Obwegeser HL, Makek MS: Hemimandibular hyperplasia—

hemimandibular elongation. J Maxillofac Surg 14:183, 19862. Wolford LM, Morales-Ryan CA, Garcia-Morales P, et al: Surgical

management of mandibular condylar hyperplasia type 1. Proc(Bayl University Med Cent) 22(4):321, 2009

3. Jones RH, Ching M: Intraoral zygomatic osteotomy for cor-rection of malar deficiency. J Oral Maxillofac Surg 53:483,1995

4. Mehra P, Wolford LM: Use of the mitek anchor in temporo-mandibular joint disc reposition surgery. Proc (Bayl UniversityMed Cent) 14(1):22, 2001

5. Temporomandibular joint ramifications of orthognathic sur-gery, Vol. 1, chapt 20, in William HB (ed). Modern Practice inOrthognathic and Reconstructive Surgery. WB Saunders, Phil-adelphia, 1992, pp 523-593

6. Wolford LM, Mehra P, Reich-Fischell O, et al: Efficacy of highcondylectomy for the management of condylar hyperplasia.Am Orthod Dentofacial Orthop 121:136, 2002

7. Wolford LM, Gatiano A: A Simple and accurate method ofmounting models in orthognathic surgery. J Oral MaxillofacSurg 65:1406, 2007

8. Ferguson JW: Definitive correction of the deformity resultingfrom hemi mandibular hyperplasia. J Craniomaxillofac Surg33:150, 2005

9. Hansson T, Carlsson GE, Kopp S: Thickness of the soft tissuelayers and the articular disk in the TMJ. Acta Odontol Scand35:77, 1977

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correction of facial asymmetry as a result of unilateral condylar hyperplasia

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