YIJOM-2688; No of Pages 8

Clinical Paper

Orthognathic Surgery

Int. J. Oral Maxillofac. Surg. 2013; xxx: xxx–xxxhttp://dx.doi.org/10.1016/j.ijom.2013.05.004, available online at http://www.sciencedirect.com

Long-term results of bilateralmandibular distractionosteogenesis using an intraoraltooth-borne device in adultClass II patientsT. H. El-Bialy, Y. Razdolsky, N. D. Kravitz, S. Dessner, R. F. Elgazzar: Long-termresults of bilateral mandibular distraction osteogenesis using an intraoral tooth-borne device in adult Class II patients. Int. J. Oral Maxillofac. Surg. 2013; xxx: xxx–xxx. # 2013 International Association of Oral and Maxillofacial Surgeons. Publishedby Elsevier Ltd. All rights reserved.

Abstract. The aim of this prospective clinical study was to evaluate the short-term andlong-term skeletal and dental changes after mandibular osteodistraction with tooth-borne appliances in adult orthodontic patients. The sample consisted of 10 non-growing Caucasian patients with a Class II skeletal relationship due to mandibulardeficiency, together with Class II dental malocclusion. All patients underwentmandibular distraction osteogenesis (MDO) using the ROD1 tooth-borne device.Lateral cephalograms were evaluated at four time intervals: pretreatment (T1), aftermandibular distraction (T2), after orthodontic fixed appliance therapy (T3), and atlong-term observation 8-year post-distraction (T4). Statistical analyses comparedthe skeletal and dental changes in intervals T1–T2, T2–T3, T3–T4, T1–T4, and T2–T4. MDO with the ROD1 tooth-borne device produced significant long-term (T1–T4) increases in the SNB angle (2.38), total mandibular length (5.9 mm), and corpuslength (4.5 mm). Potential adverse sequelae included significant increases inmandibular plane angle (4.38), lower anterior dental height (2.8 mm), and lowerposterior dental height (2.5 mm). Significant increases in lower incisor proclinationoccurred during distraction (7.58). Distraction osteogenesis with tooth-borneappliances offers a minimally invasive surgical method with stable results forcorrecting mandibular deficiency in non-growing patients.

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intraoral tooth-borne device in adult Class II patients, Int J Oral Maxillofac Surg (2013), htt

0901-5027/000001+08 $36.00/0 # 2013 International Association of Oral and Maxillofacial Surge

T. H. El-Bialy1, Y. Razdolsky2,N. D. Kravitz3, S. Dessner4,R. F. Elgazzar5,6

1Orthodontics and Biomedical Engineering,Faculty of Medicine and Dentistry, Universityof Alberta, Edmonton, Alberta, Canada;2Private Orthodontic Practice, Buffalo Grove,IL, USA; 3Private Orthodontic Practice,Chantilly, VA, USA; 4Private Oral andMaxillofacial Surgery Practice, Schaumburg,IL, USA; 5Oral and Maxillofacial SurgeryDivision, Faculty of Dentistry, University ofManitoba, Canada; 6Oral and MaxillofacialSurgery, Tanta University, Egypt

Key words: tooth-borne detractor; mandibularretrognathia; distraction osteogenesis; longterm.

Accepted for publication 14 May 2013

Introduction

The orthodontic treatment of adult Class IIpatients with mandibular retrognathia oftenentails dental camouflaging or mandibular

advancement surgery, including bilateralsagittal split or vertical ramus osteotomies.Distraction osteogenesis (DO), the biologi-cal process of new bone formation by gra-dually stretching the healing callus that

joins surgically divided bone segments,has become an important alternative surgi-cal technique for the craniofacial region.Mandibular DO (MDO) is frequently per-formed in young children with congenital

dibular distraction osteogenesis using an

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ons. Published by Elsevier Ltd. All rights reserved.

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Fig. 1. ROD1 device assembled (A) and disassembled (B).

craniofacial skeletal deformities includingsevere micrognathia,1–9 as well as childrenand adults with ankylosis of the temporo-mandibular joint (TMJ)10–13 to elongate themandible, improve function, and enhancethe soft tissue profile. However, MDO isperformed less often in adult Class IIpatients for skeletal correction of mandib-ular retrognathia.14,15

The advantages of MDO compared tothe conventional orthognathic surgeryinclude: enables extensive bone lengthen-ing16; eliminates the need for bone graft-ing16 and inter-maxillary fixation17; theincremental skeletal movements allow foraccommodation of the soft tissues15;reduces surgical stress18; and reducesthe incidence of inferior alveolar nervedysesthesia.19–21 The primary disadvan-tages of MDO include: the total length oftreatment, which may take up to 3–4months to ensure adequate stabilizationof the regenerate,16,18 and the potential forbite opening.20

The appliances used for MDO can becategorized with regard to whether theyare internal or external, the direction ofdistraction, and the site of application.22

External devices are inserted through theskin to the mandible. These devices arecapable of extensive distraction and multi-dimensional control; however they areconspicuous and bulky, and more likelyto cause traction scarring on the face.Internal or intraoral devices are attachedeither to bone or less commonly to teethadjacent to the osteotomy site. Somedevices are attached to teeth and bone(known as hybrid devices), thereby pro-viding both direct and indirect skeletalfixation. Most internal distractors are cap-able of unidirectional distraction only.22

Internal devices are less visible than exter-nal devices and will not cause scarring,though they are often limited to the extentand direction of distraction22 and the dis-traction rod may create excessive pressureon the lower lip.20

In regards to intraoral devices, tooth-borne distraction offers numerous advan-tages in comparison to bone-borne distrac-tion, including: eliminates the need for asecond surgery to remove the distractionbone Plates14; the distraction screws areremovable which maximizes the surgicalaccess; and interdental distraction osteo-tomies and seating of the device are per-formed in an outpatient setting,23 whichminimizes operation time, surgical mor-bidity, and hospital expenses.14 Despitethese advantages, the current literatureregarding bilateral intraoral MDO in adultpatients has mainly been focused on bone-borne or hybrid appliances.

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intraoral tooth-borne device in adult Class II

Hamada et al.18 presented a case reportof bilateral MDO using a bone-borneappliance for the treatment of obstructivesleep apnea syndrome (OSAS) in a 31-year-old male with severe retrognathia(SNB = 67.48). At the end of distraction,the cephalometric analyses revealed a 2.88decrease in ANB, a 3.08 increase in man-dibular plane angle (MPA), a 7.68 increasein lower incisor angulation, and a 3.5 mmincrease in LL to E-line. After 3 years and1 month of post-distraction orthodontictreatment, followed by 9 months in reten-tion, ANB relapsed slightly (0.98) and themandibular incisors further proclined(1.28), while the MPA remained constant.

Karacay et al.24 presented a case reportof MDO using the MD-DOS bone-borneappliance in a 20-year-old male with ahyperplastic maxilla (SNA = 868,ANB = 68) and excessive overjet(16 mm). At the end of consolidation(10 weeks after distraction at the time ofdevice removal), the cephalometric ana-lyses revealed a 48 decrease in ANB, an11 mm increase in total effective mandib-ular length, a 6 mm increase in corpuslength, a 78 increase in y-axis, a 158increase in lower incisor angulation, and4 mm increase in LL to E-line. At the 1-year follow-up appointment (17 monthsafter removal of the distraction device),ANB relapsed 28, total mandibular lengthrelapsed 4 mm, corpus length relapsed2 mm, y-axis returned to the original pre-treatment value, lower incisors maintainedtheir proclination, and the lower lip main-tained protrusion relative to the E-plane.

Mattick et al.17 presented three casereports of bilateral mandibular advance-ment by MDO using the intraoral bone-borne device in Class II adult patients(mean age 22 years). At the end of fixedorthodontic treatment (4–7 months post-distraction), cephalometric analysesrevealed a mean 4.78 decrease in ANB,a mean 11.1 mm increase in total effectivemandibular length, and a 1.88 decrease inlower incisor angulation.

Sadakah et al.12 performed bilateralMDO using a bone-borne appliance in

TH, et al. Long-term results of bilateral man

patients, Int J Oral Maxillofac Surg (2013), http

two adult Class II patients (mean age 29years) with TMJ ankylosis and retro-gnathia (mean SNB = 638). At a mean15 months post-distraction, the authorsreported a mean 138 increase in SNB fromthe pretreatment value, despite a mean4.5 mm of relapse in mandibular length.

In 1997, Razdolsky introduced theROD1 (Oral Osteodistraction, LP, Buf-falo Grove, IL, USA), a tooth-borne dis-traction device for multiplanar interdentaldistraction25 (Fig. 1). The main indica-tions for using ROD1 are in cases withskeletal Class II due to mandibular defi-ciency, especially when accompanied bylower incisor crowding and/or flaring inhorizontal growth pattern. Currently, noprospective clinical study has evaluatedthe long-term effects of bilateral antero-posterior MDO using a tooth-borne appli-ance in non-growing patients. The pur-pose of this study was to evaluate thelong-term skeletal and dental changesafter antero-posterior mandibular distrac-tion using the tooth-borne ROD1 distrac-tion device in Class II adult orthodonticpatients.

Materials and methods

The sample for this study consisted of 10consecutively treated adult patients (sevenmales, three females) from a private ortho-dontic practice, who underwent mandibularadvancement distraction osteogenesis usingthe ROD1 tooth-borne device. All patientspresented with a Class II skeletal relation-ship (mean ANB = 6.68) due to mandibularretrognathia (mean SNB = 73.28), Class IIdental malocclusion (mean molar relation-ship = 1.4 mm, overjet = 8.0 mm, lowercrowding of 5.1 � 1 mm, lower incisorinclination relative to mandibular plane of94.6 � 78), and average curve of Spee. Allpatients had mesocephalic facial types andnormal forward and backward growth of themandible. Sample demographics includedCaucasian patients from either first- or sec-ond-generation Eastern-European descent.

The inclusion criteria for patient selec-tion included: (1) Class II skeletal

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relationship due to mandibular retro-gnathia, (2) Class II dental malocclusion,(3) non-growing adult patient, with (4)healthy periodontium. Prior to enrollment,all patients were presented three treatmentoptions: (1) non-surgical dental camou-flage with or without upper premolarextraction, (2) mandibular advancementvia bilateral sagittal split osteotomy, or(3) mandibular interdental distractionusing the ROD1 tooth-borne distractiondevice. All patients chose the third option,i.e., mandibular interdental distractionusing the ROD1 tooth-borne distractiondevice.

Prior to fabrication of the tooth-bornedistraction appliance, presurgical ortho-dontic tooth alignment was performedwith 0.018 slot prescription twin bracketsand first molar bands. The purpose of thepresurgical orthodontics was to providethe surgeon with enough interdental spaceto perform the surgical cuts without risk-ing trauma to the neighbouring teeth. Afterbuilding to 0.016 � 0.022 stainless steelwires, the maxillary and mandibulararches were coordinated. The lower firstpremolars and second molars were fittedwith preformed stainless steel crowns(3 M Unitek, Monrovia, CA, USA), andalginate impressions were taken to transferthe bands to a heat-resistant stone modelfor laboratory processing. Patients wereprepared before surgery by the orthodon-tist who cemented the male component ofthe ROD1 appliance on the teeth adjacentto the distraction site using glass ionomercement (Fuji Ortho LC, GC America, Inc.,Alsip, IL, USA).

All patients were treated surgically bythe same oral maxillofacial surgeon. Eachsurgery was performed in an outpatientsetting under local anaesthesia and intra-venous sedation. Bilateral mandibular cor-ticotomies were performed between themandibular second premolar and the firstmolar or the first and second molar using areciprocating saw. Lateral corticotomiesextended vertically from the inferior bor-der to a point just inferior to the alveolarcrest, and transversely through the corpuswithout perforating the lingual corticalplate to prevent damage to the lingualnerves and vessels. A parallel lingual cor-ticotomy was made extending from themylohyoid ridge convexity to a point justshort of the lingual alveolar crest. Thelingual cortex was separated with anosteotome to perform a complete osteot-omy before placing the female componentof the distractor.

The distraction protocol was as follows:(1) 5 and 7 days postsurgery latency period(5 days for younger patients and 7 days for

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intraoral tooth-borne device in adult Class II

older patients); (2) distraction rate of1.0 mm/day; (3) distraction rhythm ofthree turns per day (0.33 mm/1808 turn)until proper length was attained; (4)moulding of the regenerate with an elasticchin-cup appliance, worn a minimum of14 h per day, to counteract downward pullof the suprahyoid muscles on the anteriorsegment; (5) consolidation for 6 weeksafter the last day of distraction; (6)removal of the ROD1 appliance afterradiographic evidence of bone formationor calcification of the callus (confirmed bypanoramic radiographs); (7) delay of 2–3additional months for bone remodellingalong with continued wear of the elasticchin-cup before initiating orthodontictooth movement through the new regen-erate. Arch coordination was performedduring the postsurgical orthodontics. Theretention protocol involved upper fixed 2–2, lower fixed 3–3, Upper Essex retainerand fixed retainers in the distraction areas.Inferior alveolar nerve sensation wasassessed using a two-point contact teston the lower lip before and at 3–6 monthsafter distraction.26

Lateral cephalometric radiographs werecollected at four time intervals: T1, pre-treatment; T2, end of distraction; T3, endof fixed appliances; and T4, 8 years afterfinishing orthodontic treatment. Lateralcephalometric superimpositions were per-formed for each patient using DolphinImaging 10.0 (Dolphin Imaging Solutions,Chatsworth, CA, USA) by an independentorthodontist. Superimposition was per-formed on the outlines of the anteriorcranial base and registered on the centreof the sella. Statistical analyses usingpaired t-tests compared the skeletal anddental changes between intervals T1 andT2, T2 and T3, T3 and T4, T1 and T4, andT2 and T4. Subsets of five radiographswere digitized by the same investigatorover a period of 2 weeks and comparisonof the two measurements was performedby paired t-test. There was no significantdifference at the P = 0.05 level of signifi-cance, revealing the measurements to bereliable.

Results

The mean pretreatment sample age was24.7 years (males 25.4, females 23.9) withan age range of 16–34 years. Inferior alveo-lar nerve sensory tests revealed that therewas no difference between the before andafter distraction values for all the patients,indicating that the inferior alveolar nervewas not affected by the procedure.

Figures 2–4 show clinical records ofone of the patients at different treatment

TH, et al. Long-term results of bilateral man

patients, Int J Oral Maxillofac Surg (2013), htt

times. Figure 5 shows cephalometricsuperimposition of the average values ofthe 10 patients at different treatment times.

Descriptive statistics and statisticalcomparisons for cephalometric skeletaland dental changes at the four treatmentintervals are presented in Tables 1 and 2.At the end of distraction (T1–T2), signifi-cant increases occurred in the SNB angle(1.98), total mandibular length (5.0 mm),corpus length (4.6 mm), MPA (5.38),lower incisor proclination (7.98), loweranterior dental height (1.3 mm), lowerposterior dental height (2.7 mm), andlower lip protrusion (1.4 mm).

By the debonding appointment (T2–T3), significant decreases had occurredin lower incisor angulation (�14.78) andlower lip protrusion (�3.6 mm); however,lower anterior dental height continued toincrease significantly. No significantchanges occurred in the antero-posteriorposition of the mandible, MPA, corpuslength, total mandibular length, or lowerposterior dental height. At the 8-year post-distraction follow up (T3–T4), no signifi-cant changes had occurred from thedebonding appointment. Comparison ofT2–T4 revealed statistical differencesonly between T2 and T4 in the lowerincisor angulation and in the lower lipprotrusion, consistent with T2–T3.

When comparing the long-term changesfrom the presenting pretreatment cephalo-metric analyses (T1–T4), significantincreases had occurred in the SNB angle(2.38), total mandibular length (5.9 mm),corpus length (4.5 mm), MPA (4.38), aswell as lower anterior and posterior dentalheights (2.8 mm and 2.5 mm, respec-tively). The lower incisors were proclined(7.58) during distraction; however theywere uprighted by the end of the activeorthodontic treatment. There were nonoted changes in the gingival architecturesor gingival recession at the end of treat-ment or at T4.

The degree of association betweenvariable changes during treatment wasevaluated (Table 3). There was a strongcorrelation between total anterior facialheight (TAFH) changes and the changesin mandibular corpus length (Go–Gn),mandibular total length (Cd–Gn), andmandibular plane inclination to Frank-furt horizontal plane (MPA). Also, therewas a strong association between thechanges in y-axis and lower anteriorfacial height (LAFH) that confirmedthe increased facial height. Further, therewas a strong association between thechanges in lower incisor inclination toMPA and lower lip position relative tothe E-plane.

dibular distraction osteogenesis using an

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intraoral tooth-borne device in adult Class II patients, Int J Oral Maxillofac Surg (2013), http

Fig. 2. Clinical extraoral photographs for one of the patients: preoperative (A), immediatelyafter finishing distraction (B), after finishing orthodontic treatment (C), and 8 years in retention(D).

Discussion

The purpose of this preliminary prospec-tive clinical study was to evaluate theshort-term and long-term effects of bilat-eral tooth-borne osteodistraction for ClassII correction in adult patients. The finaldata collection was performed in Decem-ber 2006. The mean length of active dis-traction was 15 � 5 days. The averageperiod of orthodontic treatment post-dis-traction was 14.6 � 9 months.

The total mandibular length and corpuslength increased 5.0 mm and 4.6 mm,respectively, during osteodistraction andremained stable throughout long-termretention. The amount of distraction wasslightly less than previously reported inbone-borne studies.17,24 However, lessskeletal relapse occurred in comparisonto previous bone-borne studies withshorter post-distraction recalls.12,24,27

Furthermore, skeletal relationships in allpatients in our study were corrected duringdistraction and maintained Class I canineduring the 8-year follow-up.

Despite the increase in mandible length,the SNB angle only increased 1.98 duringdistraction, which is less than previousreports using bone-borne appliances.The modest increase in antero-posteriorposition of the mandible during the dis-traction phase was likely influenced by theopening rotation of the mandible. Karacayet al.,24 for example, reported a mean 68increase in SNB despite a 78 increase inthe y-axis. van Strijen et al.20 reported thatthe antero-posterior position of B-pointwas likely to relapse in high-anglepatients. In our study, the SNB angledid not decrease after distraction; how-ever, greater antero-posterior position ofthe mandible would have likely beenachieved with better vertical control.

The MPA increased 5.38 during distrac-tion and remained relatively constant dur-ing the 8-year follow-up period. Theseresults are consistent with similar previousbone-borne studies.18,24 For example,Hamada el al.18 reported a 38 increasein the MPA during distraction, whichremained almost constant after distraction.However, Gonzalez et al.28 reported a 4.18increase in MPA during distraction and2.78 of further opening rotation during theconsolidation period, which was likely aresult of muscular pull on the developingcallus. In this study, the opening rotationthat occurred during distraction was likelya combination of significant posterior den-tal extrusion and poor compliance with theelastic chin-cup in a few patients. It couldalso be argued that the consolidation per-iod is the main reason for the increase in

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Fig. 3. Clinical intraoral photographs of the patient in Fig. 2: preoperative (A), immediately after finishing distraction (B), after finishingorthodontic treatment (C), and 8 years in retention (D).

MPA secondary to removing the appliancebefore complete mineralization occurred,and the created interdental space wasclosed by reciprocal forces while thesuprahyoid muscles exerted importantrelapse pressure allowing clockwise man-dibular rotation. This also could contributeto the relapse in the inferior border and the

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intraoral tooth-borne device in adult Class II

Fig. 4. Lateral cephalometric and panoramic X-rafter finishing orthodontic treatment (C), and 8

increased incisor mandibular plane angle(IMPA).

The elastic chin-cup functions to reducethe MPA and control bite opening in twoways: the vertical compression minimizespull from the suprahyoid muscles andmoulds the immature regenerate, both ofwhich help guide the distracted segment

TH, et al. Long-term results of bilateral man

patients, Int J Oral Maxillofac Surg (2013), htt

ays of the patient in Figs. 2 and 3: preoperative (years in retention (D).

back into proper occlusal position. Theefficacy of regenerate moulding is welldocumented; however, there exists somedebate regarding the proper timing, dura-tion, and method of callus manipulation.Wei et al.29 advocated moulding theregenerate during the consolidation phase,whereas McCarthy et al.30 and Peltomaki

dibular distraction osteogenesis using an

p://dx.doi.org/10.1016/j.ijom.2013.05.004

A), immediately after finishing distraction (B),

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Fig. 5. Mean cephalometric changes: superimposition at different treatment times.

et al.31 advocated manipulation during theactivation phase. Regenerate moulding istypically achieved by attaching intermax-illary elastics or orthodontic springs tomaxillary archwire; however, this methodcan result in significant incisor extrusion.In our study, the regenerate was mouldedwith an elastic chin-cup during activedistraction and throughout the 6-week

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intraoral tooth-borne device in adult Class II

Table 1. Descriptive statistics for the cephalom

T1

Mean

Cephalometric variablesSNA (8) 79.9

SNB (8) 73.2

ANB (8) 6.6

MPA (8) 23.9

y-axis (SGn–FH) (8) 60.9

Go–Gn (mm) 63.6

Cd–Gn (mm) 95.7

TAFH (NaMe) (mm) 105.5

LAFH (%) 53.5

LAFH (ANS–Me) (mm) 58.8

IMPA (8) 94.6

LADH (mm) 36.4

LPDH (mm) 27.7

LL–E line (mm) �1.0

SNA, sella–nasion–A point; SNB, sella–nasion–BFrankfurt horizontal; Go, gonion; Gn, gnathion;

anterior facial height; NaMe, nasion to menton; Ldental height; LPDH, lower posterior dental hei

consolidation period. Significant increasesin bite opening and dental extrusionoccurred during the distraction phase,and only slight closure of the MPA wasobserved after removal of the distractiondevice.

There was noticeable extrusion of theanterior and posterior dental height duringthe distraction period, which was expected

TH, et al. Long-term results of bilateral man

patients, Int J Oral Maxillofac Surg (2013), http

etric analyses at the four time (T) intervals (N =

T2 T3

SD Mean SD M

3.6 79.8 3.6 73.7 75.1 3.8 73.7 4.7 3.1

6.8 29.2 6.7 24.9 61.8 4.3 67.9 68.2 5.2 66.1 100.7 5.5 103.6 110.5 4.1 113.0 55.5 2.7 53.8 63.5 3.4 67.9 102.5 8.5 81.7 37.7 2.4 31.6 30.4 1.9 21.9 0.4 2.4 �

point; ANB, A-point–nasion–B point; MPA, manGo–Gn, mandibular corpus length; Cd, condyle;

AFH, lower anterior facial height; IMPA, incisor mght; LL–E line, lower lip protrusion–aesthetic li

with the use of a tooth-borne appliance.The posterior dental extrusion opened thebite, weakened the antero-posterior posi-tion of B-point, and impeded the improve-ment of the Class II facial profile. Theamount of extrusion for the lower firstmolar was more than twice that of thelower incisor. Posterior dental extrusionwas likely a result of the proximity of the

dibular distraction osteogenesis using an

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10).

T4

ean SD Mean SD

9.7 3.5 79.8 3.65.5 3.8 75.6 3.84.3 2.6 4.2 2.68.6 7.1 28.2 6.61.3 4.4 61.3 4.28.8 4.5 68.2 5.31.6 5.3 101.6 5.40.5 4.9 110.3 4.95.5 2.2 55.2 2.43.2 3.2 62.9 3.37.8 4.1 87.1 7.59.1 2.1 39.2 2.19.8 2.1 29.9 2.33.2 2.0 �3.0 2.6

dibular plane angle; SGn, sella–gnathion; FH,Cd–Gn, mandibular total length; TAFH, total

andibular plane angle; LADH, lower anteriorne.

Long-term results of tooth-borne MDO 7

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Table 2. Statistical comparisons for cephalometric changes at the four time (T) intervals.

T1–T2 T2–T3 T3–T4 T1–T4 T2–T4

Mean SD P-value Mean SD P-value Mean SD P-value Mean SD P-value Mean SD P-value

Cephalometric variablesSNA (8) �0.1* 0.1 0.012 0.0 0.3 0.601 0.1 0.3 0.199 0.0 0.3 0.719 0.1 0.3 0.515SNB (8) 1.9* 1.8 0.011 0.4 1.0 0.218 0.1 0.3 0.466 2.3* 2.0 0.005 0.5 1.2 0.232ANB (8) �1.9* 1.8 0.009 �0.5 1.2 0.677 �0.1 0.4 0.705 �2.4* 2.0 0.005 �0.4 1.4 0.338MPA (8) 5.3* 1.6 0.000 �0.6 1.2 0.152 �0.4 0.6 0.066 4.3* 2.4 0.000 �1.0* 1.2 0.035y-axis (SGn–FH) (8) 0.9 1.3 0.045 �0.6 1.2 0.160 0.0 0.4 0.943 0.4 2.3 0.619 �0.5 1.3 0.218Go–Gn (mm) 4.6* 3.4 0.002 0.5 2.3 0.474 �0.6 1.5 0.234 4.5* 3.4 0.002 �0.1 2.2 0.933Cd–Gn (mm) 5.0* 2.6 0.000 0.9 1.3 0.055 0.0 0.7 0.892 5.9* 2.9 0.000 0.9 1.7 0.109TAFH (NaMe) (mm) 5.0* 1.8 0.000 0.0 1.6 0.969 �0.1 0.7 0.552 4.8* 2.7 0.000 �0.2 1.8 0.780LAFH (%) 2.0* 0.7 0.000 �0.1 0.7 0.785 �0.3 0.3 0.049 1.7* 1.0 0.000 �0.3 0.7 0.182LAFH (ANS–Me) (mm) 4.7* 1.6 0.000 �0.4 1.6 0.517 �0.3 0.7 0.234 4.1* 2.5 0.001 �0.6 1.7 0.267IMPA (8) 7.9* 5.8 0.006 �14.7* 7.6 0.000 �0.7 3.1 0.769 �7.5* 6.3 0.005 �15.4* 6.7 0.000LADH (mm) 1.3* 1.8 0.024 1.4 2.0 0.080 0.1 0.6 0.833 2.8* 1.1 0.000 1.5* 1.7 0.022LPDH (mm) 2.7* 1.3 0.000 �0.6 1.3 0.260 0.1 0.5 0.684 2.5* 1.7 0.005 �0.4 1.2 0.308LL–E line (mm) 1.4 2.9 0.272 �3.6* 1.5 0.000 0.3 1.2 1.0 3.1* 2.6 0.023 �3.3* 2.1 0.001

SNA, sella–nasion–A point; SNB, sella–nasion–B point; ANB, A-point–nasion–B point; MPA, mandibular plane angle; SGn, sella–gnathion; FH,Frankfurt horizontal; Go, gonion; Gn, gnathion; Go–Gn, mandibular corpus length; Cd, condyle; Cd–Gn, mandibular total length; TAFH, totalanterior facial height; NaMe, nasion to menton; LAFH, lower anterior facial height; IMPA, incisor mandibular plane angle; LADH, lower anteriordental height; LPDH, lower posterior dental height; LL–E line, lower lip protrusion–aesthetic line.

* Significant comparison, P < 0.05.

distraction device, whereas the anteriordental extrusion may have occurred as asequela of bite opening. The slight relapsein posterior dental height, which occurredby the end of fixed appliances, corre-sponded with the slight closure in MPA.

The lower incisors were proclined 7.98during the distraction and were uprightedby the completion of the fixed appliances.The significant advancement and proclina-tion of the lower incisors was consistentwith previous bone-borne studies.18,24 Theuprighting of the lower incisors was greaterthan described in previous reports, and was

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Table 3. The degree of association betweenvariable changes during treatment as evalu-ated by T1–T4.

Cephalometric variables r* P-value

TAFH and Go–Gn 0.91 0.0001TAFH and Cd–Gn 0.87 0.001TAFH and MPA 0.69 0.03LAFH and Go–Gn 0.75 0.011Cd–Gn and Go–Gn 0.89 0.001y-axis and MPA 0.77 0.01TAFH and LADH 0.83 0.003TAFH and LPDH 0.85 0.002LL–E line and L1/MPA 0.64 0.047

TAFH, total anterior facial height; Go,gonion; Gn, gnathion; Go–Gn, mandibularcorpus length; Cd, condyle; Cd–Gn, mandib-ular total length; MPA, mandibular planeangle; LAFH, lower anterior facial height;LADH, lower anterior dental height; LPDH,lower posterior dental height; LL–E line,lower lip protrusion–aesthetic line; L1, lowercentral incisor.

* Correlation coefficient (r) for the rela-tionship between variable changes duringtreatment.

likely a result of protracting the lowersecond molar into the distraction space.

The strong association between theincreased y-axis and lower as well as totalanterior facial heights confirms the slightincrease in the vertical dimension afterdistraction. This could be due to theincreased lower anterior and posteriordental heights after distraction, as evi-denced by the strong association betweenTAFH changes and lower anterior dentalheight (LADH) as well as with lowerposterior dental height (LPDH) changes.The strong association between thechanges in the lower incisor inclinationto MPA and lower lip position relative tothe E-plane indicates that lower incisorposition is important for facial aesthetics.

There were several significant limita-tions to this study. (1) Most significantly,the treatment results were not compared toa control group. Future studies are neededto make comparative evaluations betweenthe long-term effects of bilateral tooth-borne MDO to dental camouflaging orconventional mandibular advancementsurgery with more complex mandibularmovements than 10 mm, which isexpected to be associated with counter-clockwise mandibular movements. (2)Patient compliance with the elasticchin-cup was not recorded with a dailylog. The increase in MPA and dentalextrusion indicate that actual compliancemay have been less than reported by thepatients. Future studies are needed todetermine the proper timing and appro-priate force for regenerate moulding. Inaddition, the incorporation of temporaryanchorage devices with inter-arch elastics

TH, et al. Long-term results of bilateral man

patients, Int J Oral Maxillofac Surg (2013), htt

or orthodontic springs may eliminate thesocial burden of wearing an extraoralappliance, control the force level, andeliminate the need for patient compliance.(3) Over the length of the study, twodifferent radiography machines wereused, one film and the other digital; thismay have resulted in tracing and super-imposition errors. (4) Cone-beam com-puted tomography scans may haveprovided better insight into the period-ontal health of the lower incisors duringdistraction. It is probable that the signifi-cant incisor proclination that occurredduring distraction may have influencedthe periodontium since we did not witnessany gingival recession even after T4.

Based on this study, we can concludethat tooth-borne MDO could be used as analternative to orthognathic surgery forcases with a skeletal Class II relationshiptogether with Class II malocclusion. Also,future studies might be aimed to evaluatethe possibility of root resorption withorthodontic treatment using tooth-bornedistraction devices. It should be noted thatcost and time are two important factors,particularly in busy clinics and with self-paid patients. However, the DO techniqueis not meant to replace the current well-established orthognathic techniques,rather it may be considered as a usefulreliable technique in selected candidates.Another recommendation to improve thepatient’s profile with compromised aes-thetics when noticed with most of theDO techniques used for the treatment ofClass II patients, is that advancementgenioplasty can easily be done separatelyif it is indicated.

dibular distraction osteogenesis using an

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8 El-Bialy et al.

YIJOM-2688; No of Pages 8

It can be suggested within the limita-tions of the current study that intraoraldistraction using tooth-borne distractiondevices appears to be predictable andstable. No complications were seen inthe treated samples compared to publishedcomplications with other bone-borne dis-traction devices.

The results of this study may help clin-icians to select the correct surgical inter-vention and proper appliance according tothe planned treatment, in terms of amountof movement, age of the patient, occlusalplane, and preserving the inferior alveolarnerve (movements over 20% of the man-dibular body length should be done ante-rior to the nerve, or sagittal splitdistraction).

Funding

American Association of OrthodontistsFoundation.

Competing interests

None.

Ethical approval

Institutional Review Board of the Univer-sity of Illinois at Chicago.

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Address:Reda Fouad Elgazzar343–790 Bannatyne AvenueWinnipegManitobaR3E 0W2 CanadaE-mails: reda.elgazzar@ad.umanitoba.ca,reda_elgazzar@yahoo.co.uk

dibular distraction osteogenesis using an

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