1Department of Oral and MaxillofacialSurgery, Isala Clinics Zwolle, TheNetherlands; 2Department of Oral andMaxillofacial Surgery, University MedicalCenter Groningen, The Netherlands;3Department of Oral and MaxillofacialSurgery, Academic Medical Center/AcademicCenter for Dentistry (ACTA), University ofAmsterdam, The Netherlands

This study showed no significant difference in relapse between the BSSO and theDOG group measured 1049 months after advancement of the mandible (p > 0.05).

tion; sagittal split osteotomy; mandibular retro-gnathia.

Int. J. Oral Maxillofac. Surg. 2009; 38: 712://There is no postoperative difference in the stability between BSSO and DOG aftermandibular advancement after 1 year.

Accepted for publication 12 September 2008Available online 1 November 2008

Mandibular retrognathia is a commondentofacial deformity requiring a combi-nation of orthodontic and surgical treat-ment. The most frequently used surgicaltechnique for advancement of the mand-ible is bilateral sagittal split osteotomy(BSSO)16,23. In patients with a normal or

decreased facial height BSSO for man-dibular advancement is considered a verystable procedure14,16. A high mandibularplane is seen as a major aetiologicalfactor contributing to postoperative ske-letal relapse7,16. In larger advancementsthe relapse appears to be multifactorial

and is related to the amount of advance-ment6,7,16. One factor assumed to contri-bute to this relapse is the acute stretchingof the soft tissues, including muscles andtendons.

Since the initial introduction of distrac-tion osteogenesis (DOG) of the humanAbstract. The aim of this study was to compare the postoperative stability of themandible after a bilateral lengthening procedure, either by bilateral sagittal splitosteotomy (BSSO) or distraction osteogenesis (DOG). All patients who underwentmandibular advancement surgery between March 2001 and June 2004 wereevaluated; 26 patients in the BSSO group and 27 patients in the DOG group wereincluded. The decision to use the intraoral distraction or BSSO for mandibularadvancement primarily depended on the patients choice.

In both groups, standardized cephalometric radiographs were takenpreoperatively, postoperatively (BSSO group) or directly post-distraction (DOGgroup) and during the last study measurement in May 2005. The cephalometricanalysis was performed using the following measurements: Sella/NasionMandibular point B and Sella/NasionMandibular Plane. Point B was used toestimate relapse.M. D. Vos, E. M. Baas, J. de Lange, F. Bierenbroodspot: Stability of mandibularadvancement procedures: Bilateral sagittal split osteotomy versus distractionosteogenesis. Int. J. Oral Maxillofac. Surg. 2009; 38: 712. # 2008 InternationalAssociation of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rightsreserved.0901-5027/0107 + 06 $30.00/0 # 2008 International Association of Oral and Maxillofacial SurgeonKeywords: relapse; mandibular advancement;distraction osteogenesis; mandibular distrac-Stability of mandibularadvancement procedures:Bilateral sagittal split osteotomyversus distraction osteogenesisClinical Paper

Orthognathic Surgery

M. D. Vos1,2, E. M. Baas1, J. deLange1,3, F. Bierenbroodspot1doi:10.1016/j.ijom.2008.09.007, available online at http www.sciencedirect.coms. Published by Elsevier Ltd. All rights reserved.

mandible by the German craniofacial sur-geon Rosenthal in 19279 and after a reportof distraction osteogenesis of the mandiblein four young patients by McCarthy in199212, distraction of the mandible hasbeen evolved. Intraoral DOG for length-ening the mandible is now proposed as analternative to BSSO21,22. Increased stabi-lity is thought to be one of the mainadvantages of DOG23. Gradual stretchingof the soft tissues, less periosteal stripping,and positioning the site of the osteotomydistal to the pterygomasseteric sling areconsidered beneficial to the stability of theprocedure20. A reduced risk of permanentnerve damage after intraoral distractionhas been reported1,25. Lengthening ofthe mandible can be increased to a greaterextent than can be achieved by conven-tional surgery without the need for bonegrafts. The duration of orthodontic treat-ment with intra-oral mandibular distrac-tion is significantly shorter compared withmandibular lengthening with BSSO3.

There are insufficient data in the litera-ture comparing BSSO and DOG of themandible, especially on relapse. This ret-rospective pilot study was carried out to

for correction of a mandibular retrognatiatreated between March 2001 and June2004 were evaluated. All patients includedwere treated in The Isala Clinics, Zwolle,The Netherlands.

The DOG group comprised 30 patientsand the BSSO group 35 patients. In theDOG group, 3 patients were excludedbecause of insufficient data. Therefore,27 patients were included in this group ofwhom 14 were male and 13 were female.The mean age at the time of surgery was 19years (range 1441 years). In the BSSOgroup, 9 patients were excluded because ofinsufficient data, leaving 26 patients: 4 menand 22 women. The mean age at the time ofsurgery was 28 years (range 1750 years).All patients had orthodontic appliances inplace at time of the surgical treatment. Thedecision to use intraoral distraction orBSSO for mandibular advancement pri-marily depended on the patients choiceafter extensive consultation with themand their parents on both types of surgery.

In both groups, the clinical measure-ments and cephalometric radiographswere taken preoperatively, postopera-tively or in the DOG-group directly

identified at the lingula, where the medial

intermaxillary wires with a thin interoc-

8 Vos et al.

fMaterials and Methods

In this retrospective study, all patientswith surgical lengthening of the mandible

Fig. 1. The landmarks and measurements usedtext.compare the postoperative stability of themandible after bilateral lengthening bymeans of BSSO and DOG.post-distraction (T1) and during the laststudy measurement in May 2005 (T2). Asa basis for the cephalometric measure-ments, an xy cranial base coordinatesystem was constructed. For the x-axisthe SellaNasion line was used. A con-structed vertical reference line was drawnperpendicular to this line at Sella (y-axis).

or the cephalometric analysis described in theclusal acrylic splint (wafer) in place. Tita-nium miniplates were used to fix thefragments. The proximal fragments werepositioned with a gauze-packing instru-ment to guide the proximal fragment intothe proper posterior position in the glenoidfossa. The miniplates were bent, posi-tioned passively against the bony frag-ments and fixed with at least twomonocortical 5 or 7 mm screws on eachside of the osteotomy. The intermaxillaryhorizontal osteotomy cut was made with aLindemann bur, just above the lingula andparallel with the occlusal plane. The obli-que and buccal cuts were made. Finally,the lower border of the mandible was cutwith the Lindemann bur. The osteotomy ofthe mandible was performed. Afteradvancement, the mandible was fixed inthe planned occlusion with stainless-steelAnalysis was performedusing the followingmeasurements: Sella/NasionMandibularpoint B (SNB), Sella/NasionMandibularplane (SNMP), XB and YB. Point Bwas used to estimate relapse (Fig. 1).

All the cephalographs were traced by oneperson, by hand. Superimposition of theradiographs was performed using the man-ual geometric superimposition method8.

The follow-up period varied from 10 to49 months.

The surgical procedure

In both groups the surgery was performedunder general anaesthesia. Preoperatively2 g cefazolin and 0.5 mg/kg dexametha-sone were given intravenously. Postopera-tive, after 8 and 16 hours, another 10 mgdexamethasone was given intravenously.

BSSO

A few weeks before the surgery new den-tal casts and a bite registration were made.These were used for the preoperative castsurgery. An interocclusal acrylic splintwas made, which was used during thesurgery. The bilateral sagittal splitadvancement osteotomy was carried outaccording to Obwegeser/Dal Pont modi-fied by HUNSUCK11. After infiltration of themucosa with Ultracaine, an intraoral ves-tibular incision and mucoperiosteal flapwas performed in the region of the plannedosteotomy. Following stripping of thetemporalis muscle insertion, the soft tis-sues were retracted. A periosteal elevatorwas then introduced subperiosteal on themedial aspect of the ramus, above theforamen. The inferior alveolar nerve was

lingually placed, curved chisel and finally

two groups was significant (p < 0.01). Inthe BSSO group, more women weretreated. Also the mean age between thetwo groups was significantly different(p < 0.01). The patients in the DOG groupwere younger. The mean advancement ofthe mandible in both groups was compar-able. In the BSSO group, the lengtheningvaried from 4 to 9 mm (mean 7.23 mm). Inthe DOG the lengthening varied from 5 to12 mm (mean 7.81 mm). A high mandib-ular plane (SNMP > 38) was seen in 6

long-term data on skeletal relapse after

Stability of mandibular advancement procedures 9

&with the Smith forceps and a siphon inthe lower border of the jaw. Great carefixation was released and the occlusionwas checked.

DOG

The mucosa was infiltrated with Ultra-caine. After exposing the mandibular bodyand angle, the buccal vertical cut wasmade with the Lindemann bur just behindthe second molar. The lower border of themandible was cut. If the third molar wasstill in place, it was removed. With afissure bur, a cut was made distal of thesecond molar in the buccal to lingualdirection. The mono-directional distractordevice (Zurich Distractor, Martin GmbH& Co, Tuttlingen, Germany) (Fig. 2) wasadapted and placed with at least twomonocortical screws on each side of thedistractor device . It was placed parallelto the occlusal plane. After removing thescrews and the distractor device, theosteotomy was completed, first with a

Fig. 2. The Zurich Distractor (Martin GmbHwas taken not to penetrate the spongiousbone and only cutting the cortical bone inorder to protect the inferior alveolar nerve.The distractor device was placed in themarked position and fixed on each sidewith three monocortical screws . The mostdorsal screws were placed transcuta-neously. Before closure of the wounds,the functioning of the distractor devicewas checked. After a latency period of57 days, the distractor devices were acti-vated twice a day, resulting in a 1.0 mmlengthening of the distractor device everyday. Distraction was continued until aClass I occlusion was reached. Whenthe optimal position had been achieved,a consolidation period of 810 weeksfollowed, after which the devices wereremoved under general anaesthesia.Statistics

The data were analyzed using the Statis-tical Package of Social Sciences (SPSS,Chicago, IL) version 13.0. The differencein age was analysed using Students t-testand the difference in gender was comparedusing a Pearsons X2 test. The measure-ment data were subjected to multipleregression analysis to identify and elim-inate possible confounding by age andgender.Post-surgical protocol

The patients in the BSSO group had tomaintain a soft diet for 6 weeks. In theDOG group, patients were kept on a softdiet until 6 weeks after completing thedistraction. After both procedures theorthodontic treatment continued and, ifnecessary, elastic traction was used,mostly in patients who showed signs ofan anterior open bite. Patients were seenand instructed by an oral hygienist atregular intervals.Co, Tuttlingen, Germany) used in the study.Results

A total of 26 patients in the BSSO groupand 27 patients in the DOG group wereincluded in the study (Table 1). The dif-ference in gender distribution between the

Table 1. Mean characteristics of bilateral sagosteogenesis (DOG) groups.

Number of patients includedMenWomenMean age (in years) and rangeMean advancement (in mm) and rangeSNMP < 38o (number of patients)SNMP > 38o (number of patients)DOG. To the authors knowledge thereare no clinical studies comparing the sta-bility of the two surgical procedures foradvancement of the mandible. It is diffi-cult, therefore, to compare the results ofthe present study with results found in theliterature.

In the present study, the authors did notfind a significant difference in relapsebetween the BSSO and the DOG groups,while the mean distance of advancementwas comparable in both groups. A possibleexplanation for this result could be that thedifference in relapse between the twosurgical techniques is very small and more

ittal split osteotomy (BSSO) and distraction

BSSO DOG

26 274 14

22 1328 (1750) 19 (1441)7.23 (49) 7.81 (512)

20 216 6patients in the BSSO group and in 6patients in the DOG group. The remainingpatients had a normal to low mandibularplane. There was no difference in relapsebetween patients with a high or normal tolow mandibular plane. Age and genderwere statistically identified as confoun-ders. After elimination of confounding,analyses of SNB, XB and YB(Fig. 1) (Table 2) at T1 (postoperativeor post-distraction) and T2 (last studymeasurement in May 2005) between theBSSO and DOG group showed no signifi-cant difference (p > 0.05) in all measure-ments.

Discussion

A number of studies have describedskeletal relapse after mandibularadvancement using a BSSO procedure.Recently, only retrospective reports ofthe stability of DOG of the mandible havebeen published4,20,25. There is a lack of

10 Vos et al.

e 1

X

,patients would be needed to demonstrate adifference. The follow-up period couldalso be too short. For BSSO, PROFFITet al. observed a decreased mandibularlength between 1 and 5 years post-treat-ment in about 20% of the patients with amandibular advancement14. EGGENSPER-GER et al. observed a continued relapseafter BSSO, reaching 50% of the mandib-ular advancement 12 years after surgery6.When the first patients underwent a DOGprocedure at the beginning of 2001, therewas not as much experience with thisprocedure as with BSSO. The learningcurve for DOG might affect the long-termstability; more postoperative infections ofthe distraction site were seen in the earlygroup, possibly leading to prolonged boneformation and more relapse.

There was a significant difference in themean age and in gender distributionbetween the two groups in this study.The patients in the DOG group were sig-nificantly younger and the BSSO groupconsisted of significantly more women.Statistical analyses demonstrated thatboth differences had an influence on theoutcome. Though, it is not known what

Table 2. Mean relapse from the three measuremstudy measurement in May 2005).

Operation

BSSO N

MeanStd. Error of MeanMedianStd. Deviation

DOG N

MeanStd. Error of MeanMedianStd. Deviation

P value

BSSO, bilateral sagittal split osteotomy; DOGexact biological influence age or genderhave on skeletal relapse, morphologicalbone changes due to aging could have anegative effect on stability. Hormonaldifferences between the sexes could alsoplay a role in treatment outcome and thisshould be taken into account. In the DOGgroup, several patients aged 14 or 15 yearswere included. Previously, these patientshad been unsuccessfully treated with anorthodontic activator. There might be abias due to additional mandibular growthin these patients after the surgical treat-ment, although this seems unlikely as theorthodontic activator failed to reduce theoverjet.

All lateral cephalograms of the patientsin both groups were analogue radiographicimages. In the literature, the analoguecephalometric measurements providesimilar results as the digital measure-ments13,15. In this study it was decidedto hand-trace the radiographs. In a recentstudy, GLIDDON et al. compared the accu-racy of cephalometric tracing superimpo-sition. They concluded that the manualgeometric superimposition method, wherethey manually rotated and translated thetracings to best fit the traced geometricstructures, was more accurate than thetraditional methods8. The superimpositionof the radiographs in this study was per-formed using this manual geometricsuperimposition method. Cephalometri-cally, the horizontal and vertical move-ments of the skeletal chin were measuredat point B, supported by the measurementof the SNB angle.

In current literature, several possibleadvantages of intraoral DOG of the mand-ible over traditional surgical techniqueshave been described. BSSO procedureswith an advancement up to 7 mm inpatients with a low or normal mandibularplane angle with rigid fixation are con-sidered to be stable. Mandibular ad-

nts on the cephalometric radiographs between T

SN-B (degrees)

Valid 26Missing 0

0.9.18

0.0.89

Valid 27Missing 0

.21.13.00.68.22

distraction osteogenesis.vancements of more than 7 mm andadvancements in patients with a highmandibular plane are at risk of relapse7,16.It is advocated that DOG causes lessrelapse due to gradual stretching of thesoft tissues, less periosteal stripping andpositioning of the osteotomy site distal tothe pterygomasseteric muscular sling20.Although the results are promising, espe-cially for large advancements, an excep-tion has to be made for patients with a highmandibular plane, who are thought to beat risk of significant relapse after BSSO aswell as after DOG7,16,20. It is difficult toachieve a mandibular advancement over15 mm with a BSSO, because of resis-tance of the soft tissues and problems withmaintaining adequate bony contact forosseous healing. Using DOG, significantlengthening of the mandible up to morethan 20 mm can be obtained without theneed for bone grafting17, thereby reducingthe morbidity associated with this proce-dure. Also, alignment of the proximal anddistal segments after a large advancementcan be difficult with a BSSO, due to lateralflaring of the proximal fragment. Thismay result in a lateral shift of the man-dibular condyle, thereby contributing to apossible internal derangement of the tem-poromandibular joint24.

Skeletal relapse which is measured atpoint B is thought to be a complex multi-factor phenomenon. One of the eventualskeletal changes seen after a BSSO iscondylar resorption. Surgical compressionof the condyle and changed biomechanicsof the condylar ramus segment have beenmentioned as reasons for condylar resorp-tion10. DOG is assumed to cause gradualloading of the temporomandibular jointsrather than the acute joint loading asso-ciated with BSSO. It is thought that thisgradual loading may prevent condylarresorption16,20.

When compared with BSSO, it is often

(postoperative or post-distraction) and T2 (last

-B (millimeters) Y-B (millimeters)

26 260 00.5 0.4

0.4 0.41.0 0.3

2.3 1.827 270 01.1 0.1

0.5 0.30.5 0.0

2.7 1.6.87 .78assumed that DOG may offer the advan-tage of safe application for mandibularadvancement in growing children. Thisearlier intervention can have the advan-tage of an uninterrupted orthodontic treat-ment, thereby saving time and money. Theresults of the present study show that theresults of DOG in adolescents are quitestable. BREUNING et al. showed that thetotal treatment time for the combinedorthodontic and surgical treatment inpatients with Angle Class II malocclusionswas significantly shorter in patients treatedwith fixed appliances and DOG comparedwith patients treated using fixed appli-ances and BSSO3.

One of the major disadvantages ofBSSO is the risk of neurosensory impair-

sation of sagittal split advancementosteotomies with miniplates: a prospec-

Andersen B, Tuinzing DB. Duration of

Stability of mandibular advancement procedures 11ment of the lower alveolar nerve, whichmay be temporary or permanent. Thisneurosensory impairment can result fromdirect trauma to the nerve but it can also bepresent when no apparent injury hasoccurred at the time of surgery. Simplemanipulation of the nerve during surgeryand stretching can result in neurosensoryabnormalities. In DOG, the number ofneurosensory disturbances may be lowerbecause of less manipulation and gradualstretching of the nerve. There is no stretch-ing of the nerve at the medial site ofthe ramus because it is not necessary toidentify the entrance of the nerve to themandible. There is insufficient evidencein the literature to support these assumedimproved neurosensory outcomes. VANSTRIJEN et al. reported 2% hypoesthesiaafter DOG of the mandible 12 monthsafter removal of the distraction devices19.In a group of 5 patients, WHITESIDES et al.found that all 10 inferior alveolar nervesshowed function consistent with or verynear presurgical levels at 1 year post-dis-traction25. In a prospective study afterBSSO BORSTLAP et al. reported normalfunction of the alveolar nerve 2 yearspostoperatively in approximately 88% ofthe patients, while 94% had no complaintsabout hypaesthesia2.

The BSSO is the most commonly per-formed operation for correction of man-dibular deficiency16,23. Many surgeonshave little experience with DOG. DOGis technique sensitive and the surgicalskills and experience of the surgeon canoptimize treatment outcomes and reducethe complication rate. Experience withDOG is increasing, but it is a more timeconsuming and expensive procedure thanBSSO. The distraction procedure is moreexpensive mainly because of the cost ofthe distraction devices5,18. With theincreased use of DOG, it is possible thatthe prices of the distraction devices willdrop. Re-use of these expensive devicesmay be considered in the future.

The reported complications of DOG ofthe mandible are low17,19. The complica-tions in relation to distraction osteogenesisare similar to those encountered withBSSO19. Van STRIJEN et al. reported apostoperative infection rate of 3% afterplacement of the distraction device. Theseinfections appeared to have a minimaleffect on the distraction regenerate. Theyalso reported 3% device-related problemsduring the active distraction19. Comparedwith the BSSO, DOG is accompanied bygreater patient discomfort during andshortly after treatment. A second surgicalintervention is needed to remove the dis-traction devices. The patient undergoingorthodontic treatment and mandibularlengthening by means of distraction orbilateral sagittal osteotomy in patientswith Angle Class II malocclusions. AmJ Orthod Dentofacial Orthop 2005: 127:2529.

4. Breuning KH, van Strijen PJ, Prahl-Andersen B, Tuinzing DB. The over-bite and intraoral mandibular distractionosteogenesis. J Craniofac Surg 2004: 32:119125.

5. Breuning KH, van Strijen PJ, Prahl-Andersen B, Tuinzing DB. Outcome oftreatment of Class II malocclusion byintraoral mandibular distraction. Br J OralMaxillofac Surg 2004: 42: 520525.

6. Eggensperger N, Smolka W, Luder J,Iizuka T. Short-and long-term skeletalrelapse after mandibular advancementsurgery. Int J Oral Maxillofac Surg2006: 35: 3642.

7. Eggensperger N, Smolka W, Rahal A,Iizuka T. Skeletal relapse after mandib-ular advancement and setback in single-tive multicentre study with two-year fol-low-up. Part I. Clinical parameters. Int JOral Maxillofac Surg 2004: 33: 433441.

3. Breuning KH, van Strijen PJ, Prahl-distraction must be willing to activatetwice a day during the active distractionperiod and frequent visits to the hospitalduring the active distraction period arerequired. One of the most obvious advan-tages of traditional orthognathic surgery isthe ability to complete the correction inone surgical event.

The results of this study suggest thatthere is no significant difference inrelapse between BSSO and DOG, mea-sured 1049 months after mandibularadvancement. The mean lengthening ofthe mandible was comparable in bothgroups. This means that a relativelynew technique proved to be as stableas BSSO. More experience and under-standing of the advantages and disadvan-tages of DOG could lead to better resultsin the future. DOG involves more patientdiscomfort and is more expensive.

Source(s) of support in the form ofgrants

None.

References

1. Block MS, Daire J, Stover J, Mat-thews M. Changes in the inferior nervefollowing mandibular lengthening in theDOG using distraction osteogenesis. JOral Maxillofac Surg 1993: 51: 652660.

2. Borstlap WA, Stoelinga PJW, Hop-penreijs TJM, vant Hof MA. Stabili-jaw surgery. J Oral Maxillofac Surg 2004:62: 14861496.

8. Gliddon MJ, Xia JJ, Gateno J, WongHTF, Lasky RE, Teichgraeber JF, JiaX, Liebschner MAK, Lemoine JJ. Theaccuracy of cephalometric tracing super-imposition. J Oral Maxillofac Surg 2006:64: 194202.

9. Honig JF, Grohmann UA, Merten HA.Technical strategies: Mandibula distrac-tion osteogenesis for lengthening themandible to correct a malocclusion: Amore than 70-year-old German conceptin craniofacial surgery. J Craniofac Surg2002: 13: 9698.

10. Huang YL, Pogrel MA, Kaban LB.Diagnosis and management of condylarresorption after orthognatic surgery. JOral Maxillofac Surg 1997: 55: 114119.

11. Hunsuck EE. A modified intraoral sagit-tal splitting technique for correction ofmandibular prognathism. J Oral Surg1968: 26: 249252.

12. McCarthy JG, Schreiber J, Karp N,Thorne CH, Grayson BH. Lengtheningthe human mandible by gradual distrac-tion. Plast Reconstr Surg 1992: 89: 18.

13. Ongkosuwito EM, Katsaros C, Hofvant MA, Bodegom JC, Kuijpers-Jagtman AM. The reproducibility ofcephalometric measurements: a compar-ison of analogue and digital measure-ments. Eur J Orthod 2002: 24: 655665.

14. Proffit WR, Turvey TA, Phillips C.The hierarchy of stability and predictabil-ity in orthognatic surgery with rigid fixa-tion: an update and extension. Head &Face Medicine 2007: 3: 21.

15. Santoro M, Jarjoura K, CangialosiTJ. Accuracy of digital and analoguecephalometric measurements assessedwith the sandwich technique. Am JOrthod Dentofacial Orthop 2006: 129:345351.

16. Schreuder WH, Jansma J, BiermanMWJ, Vissink A. Distraction osteogen-esis versus bilateral sagittal split osteot-omy for advancement of the retrognaticmandible: a review of the literature. Int JOral Maxillofac Surg 2007: 36: 103110.

17. Swennen G, Schliephake H, Dempf R,Schierle H, Malevez C. Craniofacialdistraction osteogenesis: a review ofthe literature. Part 1: clinical studies.Int J Oral Maxillofac Surg 2001: 30:89103.

18. van Strijen PJ, Breuning KH, Beck-ing AG, Perdijk FBT, Tuinzing DB.Cost, operation and hospitalisation timesin distraction osteogenesis versus sagittalsplit osteotomy. J Cranio-MaxillofacSurg 2003: 31: 4245.

19. van Strijen PJ, Breuning KH, Beck-ing AG, Perdijk FBT, Tuinzing DB.Complications in bilateral mandibulardistraction osteogenesis using internaldevices. Oral Surg Oral Med Oral PatholOral Radiol Endod 2003: 96: 392397.

20. van Strijen PJ, Breuning KH, Beck-ing AG, Tuinzing DB. Stability after

distraction osteogenesis to lengthen themandible: results in 50 patients. J OralMaxillofac Surg 2004: 62: 304307.

21. van Strijen PJ, Perdijk FB, BeckingAG, Breuning KH. Distraction osteo-genesis for mandibular advancement.Int J Oral Maxillofac Surg 2000: 29:8185.

22. VAN STRIJEN PJ, PERDIJK FBT, BREUNINGKH. Osteo-distraction in Class II deficien-cies, the treatment of choice? In: DinerPA, Vasquez M (Eds.) Proceedings ofthe 2nd International Congress on Cranialand facial Bone Distraction Processes.

Bologna, Italy: Mondruzzi; 1999. p. 259-263.

23. Tucker MR. Management of severemandibular retrognathia in the adultpatient using traditional orthognatic sur-gery. J Oral Maxillofac Surg 2002: 60:13341340.

24. Walker DA. Management of SevereMandibular Retrognathia in the AdultPatient Using Distraction Osteogenesis.J Oral Maxillofac Surg 2002: 60: 13411346.

25. WHITESIDES LM, MEYER RA. Effect ofdistraction osteogenesis on the severely

hypoplastic mandible and inferior alveo-lar nerve function. J Oral MaxillofacSurg: 62: 292-297.

*Address: Jan de LangeIsala KliniekenDepartment of Oral and MaxillofacialSurgery

Dokter van Heesweg 2 8000 GK ZwolleThe NetherlandsTel.: +31384245217Fax: +31 384247690E-mail: lotte.jan@wxs.nl

12 Vos et al.

Stability of mandibular advancement procedures: Bilateral sagittal split osteotomy versus distraction osteogenesisMaterials and MethodsThe surgical procedureBSSODOGPost-surgical protocolStatistics

ResultsDiscussionSource(s) of support in the form of grantsReferences