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REVIEW

Abstract

Keywords

Introduction

Sethi et al

Mandibular Distraction Osteogenesis: Bid adieu to major osteotomies - A Review

Priyanka Sethi , BDS (MDS) Post graduate Student

Sameer Patil , MDS Professor

Keluskar K.M., MDS Professor and Head

Department of Orthodontics & Dentofac ial Orthoped ics, KLE 'S Inst itute of Dental Sciences, KLE Academy of Higher Education & Research, J.N.M.e. Campus, Nehru Nagar, Belgaum-5900 10.

Majority of surgical experience with distraction technology has been in orthopaedics. Early results indicate the process to be equally effective in facial skeletal reconstruction. Distraction osteogenesis has proven to be a major advance for the treatment of several congenital and acquired mandibular deformities. A review of the literature dealing with distraction osteogenesis (DO) of the mandible is provided. The type of distraction, indications, contraindications, amount of lengthening, widening, distraction rates and rhythms, latency, relapse and the design of distraction device were analyzed. Treatment protocols and success criteria for mandibular distraction are suggested on the basis of these results. However, there is still, a lack of sufficient data which necessitates need for long term studies in the future.

Mandibular distraction osteogenesis; Lengthening; Widening.

It is not necessary to be around a surgical speciality to be a part of a revolution. Attempts to modify bone growth, both in terms of amount and direction have been made since antiquity. Intra oral and extra oral appliances are used to restrict growth of the maxilla in hopes of accentuating mandibular sagittal growth. For several decades, non-surgical distraction osteogenesis has been performed by our orthodontic colleagues in the form of rapid palatal expansion.

bone segments that are gradually separated by incremental traction 1. A traction force is applied to the bone segments which continues as long as callus tissues are stretched, resulting in generation of tension within the tissues that connect the bone segments, which stimulates new bone formation parallel to the vector of distraction.2.4

Apparently, distraction forces applied to the bone also create tension in the surrounding soft tissues initiating a sequence of adaptive changes termed distraction histiogenesis.

One of the recent techniques involving reconstruction of skeletal deformities is distraction osteogenesis. It involves gradual, controlled displacement of surgically created fractures which results in simultaneous expansion of soft tissues and bone volume. Thus distraction osteogenesis may be defined as a biologic process of new bone formation between the surfaces of

Distraction Heritage

A historical perspective is necessary to understand the genesis of the strengths as well as the weaknesses of distraction osteogeneis. Codvillas first introduced it in 1905, nearly a hundred years ago. The technique was

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subsequently popularized by a Russian orthopaedic su rgeon i I izarov,2-4 who developed a si ngle stage procedure to lengthen long bones without the use of a grafting material. In 1973, Snyder6 first described IIlizarov's technique to lengthen a surgical osteotomy of the canine model. McCarthy et ail-B were among the pioneers who used the principles of DO in craniofacial skeleton i.e. lengthening the hypoplastic mandible. Polley and Figueroa9 used a rigid, external , adjustable distraction device to lengthen the entire maxilla in children with cleft problems.

PDL distraction was first reported by Liou and HuanglO

in 1998 followed by several others. Haluk Iseri et al ll ,12 described the dentoalveolar bone distraction.

Biologic Basis of New Bone Formation

Distraction osteogenesis is one of the most mysterious phenomena of bone biology. It commences with the development of reparative callus between the edges of two bones divided by an osteotomy. The initial formation of callus is followed by an application of distraction force which gradually pulls the bone segments apart. 13

This places the callus under tension , aligning the intersegmentary gap tissue parallel to the direction of distraction. Tension stress generated in the gradually stretched tissues produces changes at both cellular and subcellular levels. This stimulates differentiation of mesenchymal cells into osteoblasts.14 The tension also enhances formation of capillaries.

Two mechanisms of bone formation have been demonstrated during DO:-

a) Intramembranous ossification with direct formation of new bone15 at a rate of 1 mm/day.

b) Endochondral ossification, in which cartilage is formed and replaced by bone through vascular invasion of capi Ilaries. 16 At relatively slower distraction rate (0.5 mm/day) endochondral ossification predominates. Hypertrophic chondrocytes present in the distraction regenerate tissue respond directly to distraction forces by forming chondroid which in turn transforms into newbone.16

The distraction force is discontinued once the desired amount of bone length is achieved. The newly formed bone (distraction regenerate) then undergoes maturation and remodeling until it becomes indistinguishable from the residual host bone.15

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Clinically distraction osteogenesis consists of five sequential steps:-

1. Osteotomy:- The bone is divided into two segments creating a loss of continuity and mechanical integrity. This is also referred to as 'fracture' . The osteotomy for mandibular lengthening is dictated by the anatomic region to be lengthened (angle, ramus, corpus) (fig. 1) and by the desired vector of lengthening which depends upon the orientation of the distraction device.17

Fig 1. c

Fig. 1 A: Ramus osteotomy; B: Angular osteotomy; C: Corpus osteotomy.

• Ramus osteotomy is indicated for vertical mandibular ramus distraction.

• Angular osteotomy is performed when downward and forward lengthening is required.

• Corpus osteotomy is performed for forward and horizontal distraction of the mandible.

2. Latency Period:- This is the period from bone division to the onset of traction. 15

3. Distraction period:- The distraction period is characterized by the application oftraction forces to the osteotomized bone segments. The bone segments are gradually pulled apart, resulting in the formation of new bony tissues with the progressively increasing intersegmentary gap.15

4. Consolidation Period:- This is the time between the removal of traction force and removal of the distraction device. It represents the time required for complete mineralization of the distraction regenerate.15

5. Remodelling Period:- This represents the interval between the application of full functional loading and complete remodeli ng of the newly formed bone.15

DISTRACTION OSTEOGENESIS

/ \ CALLOTASIS PHYSEAL DISTRACTION

/ \ DISTRACTION EPIPHYSIOLYSIS CHONDRODIATASIS

Fig 1.

Fig. 2: (From Samchucov ML, Cope JB, Cherkashin AM: Craniofacial Distraction Osteogenesis; St. Louis Mo: Mosby; 2001).

Techniques of Distraction Osteogenesis

The technique can be classified according to the site of application of tensional stress, as depicted in (Fig. 2).

Callotasis:- Distraction of the reparative callus formed around bone segments interrupted by osteotomy or fracture.'s

Physeal distraction:- Distraction of the bone growth plate.'9

a) Distraction epiphysiolysis: This technique involves separation of the epiphysis from the metaphysis at a rate of 1.0 - 1.5 mm /day.

b) Chondrodiatasis: This technique utilizes slow rate of bone segment separation (less than 0.5mm/day) and allows stretching of the growth plate without fracture.

Distraction Histiogenesis

Lengthening of the soft tissues is an important part of distraction osteogensis. Under the influence of tension stresses, a cascade of adaptive changes occur in the soft tissues. Thus distraction hi stiogenesi s may be defi ned as the biologic process of soft tissue adaptation to gradual stretchi ng.'

The sequence of adaptive changes in various tissues following mandibular osteodistraction is as follows:-

a) Effect on Skeletal Muscle:-

Guerrissi et apo performed bilateral mandibular lengthening in rabbits and histologically evaluated the surrounding soft tissues. Although no alterations in the muscle tissue were found during distraction, an increase

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in the metabolic and synthetic activities of the muscles was observed. Fisher et aP' reported that muscles oriented in a plane parallel to the distraction force adapted with compensatory regeneration , whereas muscles aligned in a plane perpendicular to the distraction force showed decreased protein synthesis and persistent evidence of atrophy.

Analyzing the effects of distraction rate on muscles Simpson et a122 confirmed that slower rate of distraction provides better muscle accommodation to limb lengthening. On the other hand rapid rates of distraction are associated with gross changes such as disorganization of muscle structure, necrosis and significant accumulation of connective tissue in the interstitium. With regard to rhythm of distraction, a more fractionated rhythm appears to provide better results23

i.e. increases in the increments of distraction lead to more effective myogenesis.

b] Effect on Nerves:

The information regarding the effect of gradual distraction on Inferior Alveolar Nerve (iAN) function is limited and controversial. Karp et aP4 reported the absence of myelinated fibres in the IAN of five dogs after 12 mm of mandibular distraction. The authors concluded that these abnormalities developed either due to the osteotomy or subsequent distraction. In contrast Michaeli et a125 found no observable histologic alterations in the IAN fibre after 5 mm and 15 mm mandibular lengthening in the same animal model. Block26 and colleagues observed mild degenerative changes after 7mm of mandibular distraction in dogs. However, these observations were limited to structural alterations only.

Makarov and co-investigators27 concentrated on IAN function during DO in dogs. They attributed the incidence of acute IAN injury to be related to device construction and osteotomy technique. If acute nerve injury is avoided at surgery, DO with 10 mm of mandibular lengthening appears to produce minimal deleterious effects on the IAN function. In a separate study on goats, Hu et aps showed that degenerative changes in the IAN were more severe and more likely to be permanent in animals distracted 2mm / day versus 1 mm/day. Whitesides et al 29 concluded that stable mandibular advancements of 10mm or greater can be successfully accomplished by distraction osteogenesis without producing significant damage to the IAN.

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c] Effect on blood vessels:

Recruitment of blood supply is critical for successful bone induction and fracture healing. Mandibular DO is associated with an intense vascular response during the early stages of distraction. The number of blood vessels in the distraction regenerate decreases significantly during later distraction.30 Also, a lower blood vessel density is found in patients with a distraction rate of 1 mm/day as compared to patients with 0.5 mm/day.

d) Effect on Gingival Tissue:

The gingival tissue responds to injury depending on the degree of trauma. If the insult is minimal , only inflammatory reactive c hanges occur, such as hyperkeratinization of gingiva.31 If the injury is sufficient to elicit an inflammatory reaction, a healing response is evoked, resulting in either complete restoration of tissue architecture (regeneration) or restoration of tissue continuity with scarring and distortion of normal tissue architecture (repair}.31 The gingiva responds favourably to gradual stretching during osteodistraction. It undergoes regeneration as opposed to repair as suggested by an inflammatory response, without any breakdown in the gingival continuity. 32

e) Effect on Periodontal Ligament:

The sequence of adaptive changes in the POL is affected by the placement of distraction forces. Whether placed directly to the bone segment or to the teeth. The mechanism of POL adaptation to gradual incremental traction during craniofacial distraction osteogenesis is similar to that of orthodontic tooth movement, where tension / compression effect on teeth and associated POL structures lead to bone resorption, osteogenesis and cementogenesis.33

Block and colleagues34,35 demonstrated greater bone segment movement after 10 mm of maxillary advancement in dogs with an implant supported bone borne distractor. However, the separated teeth moved back towards each other after completion of distraction due to elastic traction of POL transeptal fibres. They also reported that craniofacial distraction with tooth borne devices result in greater tooth movements than skeletal devices.36

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Molecular Biology of Distraction Osteogenesis

Distraction osteogenesis has augmented our armamentarium for reconstructive procedures. Therefore deciphering the molecular mechanisms that mediate mandibular distraction osteogenesis is of primary importance.

Mehrara et aP7 have demonstrated that TGF-(beta}l mRNA (transforming growth factor b-1), a major regulator of osteogenesis during endochondral bone formation and protein production, coi ncides with osteoblast migration, differentiation and extracellular matrix synthesis, They have also shown TGF (b}l production to be an important regulator of vasculogenesis during mandibular distraction osteogenesis.

Osteocalcin is a non-collagenous extra cellular protein. Warran et aP8 confirmed its marked elevation along with collagen I during the consolidation period of gradual distraction with acute lengthening. In addition, the expression of an inhibitor of extracellular matrix turnover, tissue inhibitor of metalloproteinase, was also elevated. This suggested that gradual distraction osteogenesis promotes successful osseous bone repair by regulating the expression of bone specific extracellular matrix molecules. However, an insight into the molecular mechanisms involved in distraction osteogenesis is further required since it may enable targeted therapeutic manipulations designed to accelerate osseous regeneration ,

Distraction Devices

Selection of a proper distraction device is an important consideration prior to surgery. In general, the devices can be broadly classified as follows (Fig.3):

a) Tooth borne:- The tooth borne distraction devices are fabricated according to the location, direction and amount of distraction.39,4o They are directly attached to the teeth, thereby transmitting distraction forces from the teeth to the bone via the POL. The bone element is a standard 7, 9, 11 or 13mm Hyrax screw. 39 The distal arms are soldered to the lingual surfaces of the molar bands and the mesial arms to the lingual surfaces of the premolar bands.40 The screw should be located as anterior as possible at an angle of 45 to the occlusal plane without contacting the lingual surface of mandibular anterior teeth,41 This angle

Fit:! J.

CRANIOFACIAL DISTRACTION DEVICES

/ EXTERNAL INTERNAL

1 t t

SUBCUTANEOUS INTRAORAL

BONE· BORNE . SUBMUCOSA L

-E XTRAMUCOSAL /'-,

~ TOOTRBORN[ UNIDIRECJ10NAL 80~~.!'R~~NE BIDIR[Cf IONA L ',;-___ -".li!!H' •• lli<JU'--____ --1

/ MULTIDIRECTIONAL "

Fig. 3: (From Samchucov ML, Cope JB , Cherkashin AM: Craniofacial Distraction Osteogenesis; St. Louis Mo: Mosby; 2001).

is important since it determines the ease with which the patient activates the appliance.41

b) Bone borne:- These devices are indicated when a tooth borne appliance becomes dislodged or breaks intraoperatively.42 They are also used in cases where a tooth borne distractor does not fit within the confines of the mandibular arch. 39

c) External distraction devices:- These are placed using transcutaneous pins/,43.46 are easy to place and remove during distraction, if necessary, and offer excellent control of bone segment movement especially if a multidirectional device is used.47

However, they may be poorly accepted by the patients,48,49 and may also have other disadvantages, such as skin scarring48,49, and difficulties in eating, speech, sleep, recreational activities. School attendance may also be affected.50 Therefore patient motivation and full understanding of the family is mandatory for successful completion of the treatment.50

d) Internal distraction devices:- The internal distraction devices are placed either submucosally (buried) or extra mucosally (i ntraoral). 32,39,44,45,48·54 They may be tooth borne,s3 bone borne or hybrid,52 and offer the following advantages:-

1) Internal devices neither produce scarring nor have a negative psychosocial impact.49

2) The stability of internal distractors is excellent; infection and dehiscence are rare and they are less prone to trauma. 55 However, a small external incision is necessary for accessing the activation arm which, if planned carefully, can be positioned esthetically.48

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The internal devices are not free of disadvantages, some of which are listed below:

1. High risk of injury to the nerve and other anatomic structures (e.g. ducts, tooth buds).48

2. Difficult to place when a vertical orientation of the device is required.48

3. A second surgical procedure is often necessary to remove the device following completion of consolidation Y

4. Lack of multiadjustment capability.48

e) Unilateral distraction devices:- These are placed when structures on one side of the face are affected.56,57

f) Bilateral distraction devices:- These are placed when there is a bilateral deficiency of the mandible, e.g. patients having micrognathia with bilateral mandibular hypoplasia.54,56,57

g) Unidirectional devices:- Such devices allow mandibular lengthening in one direction only. 55,58 This direction is determined by the angle between the Frankfort horizontal plane and the. distraction device.59

One of the important limitations of unidirectional devices is that they cannot be adjusted after insertion to alter the direction of lengthening. 59 Therefore the device has to be accurately placed at the time of surgery. This, however, may not always be possible because of anatomic considerations in the hypoplastic mandible such as developing tooth buds, the location of mandibular nerve and the overlying soft tissue. 59

h) Bidirectional and multidirectional devices:- They allow distraction in two directions.59 The essential components of the device are an angular joint and two geared rods of variable lengths. 59 In the bidirectional device the middle joint is a simple hinge whereas in a multidirectional device it is a multifunctional double ball joint. 59 These devices can thus be adapted according to individual anatomic situations and the components can be used to move bony segments in almost any direction during distraction.47,59

i) Resorbable distraction devices:- Though the internal metallic distraction devices offer several advantages, they can sometimes be difficult to remove. 60 Burstei n et al. 61 reported the use of internal, resorbable bone distraction devices for craniofacial applications. The resorbable devices allow a single operative procedure for device

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placement, eliminating the need for a second procedure for hardware removal. 62

Biomechanical Parameters of Osteodistraction

Success of distraction osteogenesis technique is dependent upon various biologic and biomechanical factors. Orientation of the distraction device relative to the anatomic axis of bone segment, occlusal plane, desired direction of distraction and the resulting distraction vector must be considered.

Samchukov et al63 evaluated the biomechanical effects of distractors placed parallel to the body of the mandible or parallel to the axis of distraction. The former results in a lateral displacement of the posterior component of the distraction device and a reduction of the midline distraction gap during mandibular lengthening (Fig. 4).

F"~4.

Fig. 4A: Bilateral -mandibular corpus lengthening with distractors placed parallel to the body of the mandible. B: Note lateral displacement of the posterior component resulting in an increase in the intercondylar width during lengthening (arrows) compared with the predistraction mandible (faint line). DV, Distraction vector.

BEFORE DISTRACTION

Fig6.

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These were eliminated when the device was oriented parallel to the axis of distraction (Fig. 5).

The effect of device orientation has been also evaluated in the sagittal plane by placing the device parallel to the inferior border of the mandible (Fig. 6) or parallel to the maxillary occlusal plane (Fig. 7). Distractors placed parallel to the inferior border of the mandible resulted in an increase in the lower anterior facial height during lengthening.64

The shape of the neomandible is also influenced by the vector of placement of the distraction device. 65 Ramal elongation occurs when the device is placed vertically (Fig. 8). Ramal and body elongation with preservation of the gonial angle is seen with obi ique placement (Fig. 9), whereas anterior projection of the mandibular body takes place with horizontal placement of the device (Fig. 10).

Fig. SA: Bilateral mandibular co rpus lengthening with distractors placed parallel to the axis or direction of distraction. B: there is no increase in intercondylar width during lengthening. DV, Distraction vector.

AFTER DISTRACTION

Fig. 6 A: Distractors placed parallel to the inferior border of the mandible. B: Note the inferior translation of the distal segment resulting in an increase of the lower anterior facial height during lengthening. OPmx, Maxillary occlusal plane; DV, distraction vector.

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Fig 8.

BEFORE DISTRACTION AFTER DISTRACTION

Fig 7.

Fig. 7 A : Distractors placed parallel to the maxillary occlusal plane. B: There is no increase in lower anterior facia l height during lengthening. OPmx, Maxillary occlusal plane; DV, distract ion vector.

Fig 9.

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Fig. 8: Vertical orientation of the distraction device. Fig 9: Obl ique orientation of the distraction device.

Fig 10.

Fig. 10: Horizontal orientation of the distraction device.

Indications

Osteogenic distraction is advocated in a plethora of conditions because of its unique capabilities in treating deformities of the c raniofacial skeleton. The indications of mandibular distraction osteogenesis are:- Hemifacial microsomia.7,43,49,66-86 (Facial asymmetry, hypoplasia of

m andible/ max ill ary region, hypoplasia of the facial mu sc ul ature); Segmental bone defect (Trauma, Tumour). 55,87-100; Class II. 52,58, 101.105; Acquired

mi crog nathia (Trauma, temporomandibular ankylosis) .67,71,72,73,75,106.1 12 (Retrusion of the chin or steep

m andibular angle and abnormal development of condyles); Tran sverse discrepancy - for relieving mandibu lar anterior c rowdi ng. 40,41 ,52,53,57,104, 105, 113-121 ; Craniofacial microsomia.50,82,108,1l0,122-127 (Retrusion ofthe

mandible, chin, steep mandibular angle); Treacher Collins syndrome.43,50,72,73,75.106,1l0,126'131 (Hypoplasia of the

mandible, skeletal deformities and deficiency of eye

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lashes}; Congenital micrognathia. 50,71,75,79, 106,125, 127, 131.135; Obstructive sleep apnea syndrome l,25,135.1 39 (Receding jaw, small chin, loud snoring and disrupted sleep); Alveolar defici ency 1oo,140.147; Nagers synd rome 50,71,74,75, 110, 126, 127, 130; Pie rre Robi n syndrome50,106,127,131,148 (Cleft palate, hypoplasia of mandible, glossoptosis); Goldenhar syndrome75,106,11O,122 (Hemifacial microsomia associated with ocular and vertebral involvement); Arthrogryposisl 22 (Muscular hypotonia and severe joint contractu res); Hypoglossia - Hypodactyly syndrome l06,149 (Micrognathia, retrognathia of the mandible); Hanhart Syndrome 150 (Hypoglosia , hypodacty li a, micrognathia of the mandible); Post irradiation therapy93,95, 106,151 ; Condylar resorption 152,153; Condylar hypoplasia131 ; Moebius syndrome154 (Mask like facies due facial nerve palsy, drooling incomplete eye closure and strabismus); Histiocytosis98 (Destructive osteo lytic bone lesions); Rubi nstei n-Taybi syndrome 74 (Developmental retardation of the mandible, broad thumbs and great toes); Retrognathi a72,131; Neurofibromatosis106

(Mandibular nerve involvement with the enlargement of the mandibular canal); Glossoptosis micrognathia127,148; Crouzons disease 131 ; Aglossia -micrognathia106; Silver Russel syndrome155 (Faci al asymmetry, growth retardation, micrognathia, high forehead that tapers to a small jaw); Bilateral dysostosis mandibularis ll1 (Micrognathia , ear defects with zygomatic arch involvement); Plagiocephalyl 56 (An unsymmetrical and twisted condition of the head, due to irregular closure of the cranial suture); Morpheaform scleroderma156 (Limited mouth opening, fixation of the jaws due to the involvement of peritemporomandibular joint tissue); Ammonband syndrome106.

Contrai nd ications

No absolute contraindications to treatment exist. However the relative contraindications are as follows:-157

1. Patients who are unwilling to comply with the distraction schedule are not ideal candidates for this procedure.

2. Mandibular distraction osteogenesis has been performed on infants as young as 6 months but more difficulty is encountered when dealing with small fragile bones in the placement of distraction device.

3. Distraction osteogenesis of the mandible may be used in post radiation patients. However this

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procedure must be performed with caution due to delay in wound healing.95

Orthodontics and Mandibular Distraction Osteogenesis

Mandibular deficiency is one of the most common dentofacial deformities which can present itself in all the three dimensions viz, anteroposterior, vertical and transverse. 158 In the past, these problems were treated by orthodontics alone (dental compensation) or by an orthodontic-surgical approach,1 58

More recently, distraction osteogenesis has been successfully employed in these conditions. The orthodontist, often the fi rst person to identify the deficient mandible and the need for bony distraction, participates in all stages of its treatment as a member of the multidisciplinary team.

He or she introduces the technique to the patient and the parents. Since an orthodontist plays an important role in presurgical orthodontics, he or she has an intimate understanding of the patient's occlusal relationship and finally finishes the occlusion after distraction.

Diagnosis and Treatment Planning

Mandibular distraction osteogenesis - Transverse dimension: Contasti et al41 have suggested the following clinical indications for successful mandibular expansion.

- V-shaped mandible - Severe mandibular crowding with well aligned

maxillary teeth - Brody's syndrome (scissor bite) - unilateral or

bilateral - Impacted anterior mandibular teeth with no alveolar

space. - Maxillo mandibular transverse deficiency

(crocodile bite) or tunnel smile. - Retreatment with crowding (with or without

extractions)

Aids used for diagnosis of transverse mandibular deficiency are clinical examination, cephalometric analysis, burstone soft tissue analysis159, Ricketts frontal cephalometric analysis to determine whether the transverse problems are due to tooth inclinations or skeletal deficiencies. 160 Dental Cast Analysis includes direct measurement and occlusogram gram analysis.161

Pre-distraction orthodontics: Contasti et al41 suggested that the maxillary arch should be aligned and levelled to its final desired position once the decision to surgically expand the mandible has been reached. This usually takes 6-10 months and is important since the mandible will be expanded to fit within the confines of the maxillary arch. 39

Separators are placed mesial and distal to the mandibular teeth that will support the distractor. 4 1

(Usually the 151 molars and 151 premolars). After one week, bands are fitted and an impression is taken. The bands are carefully removed from the teeth and set into the impression and a working cast is poured. The appliance is then fabricated and the screw is cemented in place, but not activated. The surgery is then scheduled one to two days later.41

Post-distraction orthodontics: Following are the most important post-surgical orthodontic considerations:-4 1

- Waiting for 7 days before activation of the device to ensure good collagen fibre formation at the distraction site.

- After the latency period of 7 -10 days, the distractor is activated 1 mm/day and the patient is seen regularly until the desired mandibular expansion has been achieved.

- Since an anterior diastema is produced by expansion in the osteotomy area, a plastic pontic with bonded bracket can be placed to maintain arch length, prevent premature mesial drifting of teeth, preserve periodontal health and provide optimal esthetics. The expansion appliance should be stabilized by covering the screw with acrylic.

- Application of a force system to co-ordinate both arches into a class I relationship.

- After consolidation (8-10 weeks) , most of the swelling and tenderness are resolved and the device is removed and replaced with new bands or brackets. A heavy round arch wire is placed. At the same appointment the denture tooth is reduced in size and an elastic chain is placed to move the teeth slowly into the distraction gap. As the space gets smaller the plastic tooth is eliminated and the residual space is closed.

- Correction of the axial inclination of the teeth in the buccal segment is done with cross elastics. Once mandibular teeth alignment and levelling is complete, a rectangular arch wire is placed for tooth torquing and stabilization of the new arch form.

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- 0.36" stainless steel lingual arch is recommended to retain the expansion. Retention ofthe mandibular arch width is not a major concern, since it is a result of basal bone width increase as opposed to orthodontic expansion.

Histologic studies by Duran et al117 have suggested that the bone exposed to stretching undergoes new bone formation and the newly formed bone is membraneous, also known as woven type. This neo formation is generally parallel .to the axis of the stretching force. Consequently it is possible to mould the newly formed bone into the required shape.

Mandibular distraction osteogenesis - Sagittal dimension: Contasti et aP9 have suggested the following indications for sagittal mandibular distraction osteogenesis.

• Mandibular advancements over 7mm • Presurgical temporomandibular joint degeneration • Sleep apnea • Inadequate mandibular anatomy

Pre-distraction orthodontics

The maxillary arch is levelled, aligned and coordinated to an ideal arch form. The mandibular arch is carefully analysed to determine the need for expansion, extractions, curve of spee levelling and in precise, the amount of bone formation required at the distraction site.39 If there is no need for expansion or extraction, fixed orthodontic appliances are bonded to the mandibular teeth to obtain a perfect arch form presurgically.

Contasti et aP9 have suggested the following records to be taken:-

1. Dental casts 2. Lateral, posteroanterior, submentovertex and

panaromic radiographs

The pre-surgical orthodontic treatment usually lasts for 6-1 0 months.

Post-distraction orthodontics: The surgical procedure is followed by the activation of the device. The distractors are stabilized after the final mandibular position is obtained. 162 Radiographic examination is performed to monitor the consolidation of the new bone. 162

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Contasti et aP9 have recommended that Class II elastics (4-6 oz/side) be worn 24 hours/day during distraction and consol idation to counteract soft tissue forces at the time of bone healing, otherwise rec iproca l forces will act against temporomandibular joint, causi ng detrimental arthritic changes in the condyle, disk and glenoid fossa. This might cause pain and discomfort to the patient. Unloading of the joints with elastics during consolidation avoids class II relapse and minimizes patient discomfort. After consolidation is complete, the arches are coordinated and orthodontic finishing procedures are initiated, which last for an additional 6 months.

Tooth movement through distracted bone

Movement of teeth through regenerate bone is a topic of current interest. Contasti et al 41 believe tooth movement should not begin until radiographic evidence of consolidation is observed after the distraction period . Closure of the interdental space should be delayed unti I the bone is observed. In the mean time mesial migration of teeth should be prevented by placing an ac ryli c denture in the distraction space. These recommendations are based on the assumption that allowing the teeth to move into the gap early can lead to periodontal defects and potential loss of teeth.

Other reports however, suggest that a tooth can be moved into the regenerate bone after the distraction period .1 63-1 65 Moderate to severe alveolar bone loss was noted in the fourth premolars moved simultaneously with distraction.164 Initiating orthodontics at the end of the distraction period preserves periodontal support. Liou et aP65 observed that orthodontic tooth movement into the newly distracted bone two weeks after the cessation of the distraction period accelerates the maturation process of the bone. They suggested that orthodontic tooth movement in a newly distracted bone is possible and the new alveolar bone thus created is mature, compact and indistinguishable from the original mandibular bone.

Nakamoto et al 166 evaluated the influence of tooth movement on tooth roots and periodontal tissues, when the teeth were moved into mature, well organized and mineralized regenerate created after DO compared with less mineralized, immature, fibrous bone. They concluded that heavy forces (80-100 gms) and orthodontic tooth movement through regenerate bone after DO are not recommended to avoid tipping and severe root resorption . Early tooth movement has no

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effects on bone maturation. Waiting for 12 weeks after distraction to initiate tooth movement resulted in a lower rate of tooth movement and lesser root resorption.

Fate of developing teeth in mandibular distraction osteogenesis

Knowledge of the development of teeth lying within the distraction area is important since mandibul ar lengthening and widen ing is often used in young children. Hagins et aP 67 reported that although the root apices closed, the shape of the roots became irregular. In addition, deformity of the proximal root has been noticed more on the side of distraction. The tooth buds in the line of mandibular fracture erupt normally but 18% exhibit either delayed eruption or non-eruption with resorption of the tooth bud. 168

Thus the developing tooth can erupt and root formation can continue in the distraction area even when the surgical procedure has influenced the tooth.168 These findings suggest that the existence of tooth buds does not restrict the type of surgical intervention, if some effort is made to preserve the dental fo llicle during operation. However pre-operative evaluation of tooth buds using radiographs is advised.

Advantages of Osteodistraction

Distraction osteogenesis is a boon and has several advantages. Several authors1 69-1 71 have emphasized the benefits of the technique as listed below:-

1. Minimally invasive 2. Short operating time 3. Elimination of the need for bone grafts thereby

avoiding donor site morbidity 4. Larger magnitudes of skeletal expansion is

possible when compared to other standard techniques.

5. Less chances for re lapse because of gradual expansion of the surrounding tissues which decreases soft tissue resistance.

6. Widening of the mandible which is difficult to do with traditional osteotomies.41

7. Obviation of the need of tracheostomy in newborns with micrognathi a and airway obstruction.127,135,138

8. When used for rapid canine retraction, there is minimal loss of anchorage, rapid distalization of canine with minimal patient discomfort. 172

Disadvantages of Osteodistraction:­

The technique may have some drawbacks. 173 • Dependence on patient compliance • Pin track scars with external devices • Long duration of treatment

Potenti al compl ications:-• Non compliant patient with treatment failure • Development of anterior open bite • Infection that may hinder osteogenesis • Scarring of the skin with external devices • Inferior alveolar nerve paresthesia

Need for overcorrection

Ideally, the mandibular advancement should be performed in a single stage. However, due to growth abnormalities, the deficiency may recur in time. Therefore, in order to compensate for growth disturbances overcorrection must be performed.56 The amount of overcorrection is calculated based on the percentage of growth deficiency, 1 .2mm of yearly mandibular growth and the duration of the remaining growth until 16 years of age.56

Potential for Relapse

If relapse after orthognathic surgery is caused by resilient soft tissue envelope and/or lack of sufficient bone contact, distraction osteogenesis might prevent this relapse by gradual distraction of the soft tissue envelope, resulting in a bone bridge of the same consistency and diameter as the original mandibular bone.174 Cope and coworkers175 have suggested that adaptive changes in the soft tissues during slower distraction procedure may minimize the potential relapse seen during acute orthopedic corrections. In support of this Fisher and colleagues21 found that the soft tissues do not tolerate stretchi ng greater than 2mm/ day. However a study conducted by Strijen et al 176

showed that high-angle patients are still at risk of relapsing and that distraction osteogenesis cannot prevent relapse in cases with high mandibular plane angle. But in patients with low-angle it is a safe and a predictable procedure.

Patient's Response to Distraction Osteogenesis

The assessment of the psychological effects and the quality of life led by the patient during the course of

Sethi et al

distraction osteogenesis is of utmost importance. Analysing from the patients perspective, it was found that majority of the patients with both intra oral and extra oral devices were satisfied with the treatment, would undergo the same again if required would and recommend it to others in their situation. 177 But a major disadvantage which they felt with extra oral devices was scarring, which did not improve with time.177 Patient's suggestions on how the intra oral devices could be improved centered around making the device less obstructive within the oral cavity, particularly by reduci ng the length of the activation rods. 177

Majority of the patients who experienced problems during treatment, were able to cope with the difficulties. 50 Patient's motivation and the full understanding of the family for this type of intervention is mandatory.5o

Future

Distraction osteogenesis is developing into an important treatment modality and has become a common place procedure with the flexibility to address a wide variety of mandibular defects. As with many new treatment concepts and techniques, the learning curve regarding distraction osteogenesis was steep and is still continuing. What we now need to assess after almost 10 yrs of experience with distraction is:-

• Its long term stability • future growth potential of a pathologic mandible

after distraction • better understanding of vectors of distraction to

achieve three dimensional changes • improve the design of the distraction devices to be

more functional, surgeon friendly and affordable.

Purposeful research, accurate recording of clinical data and critical analysis of distraction results will enable us to further refine this science into a treatment method to achieve predictable, functional, aesthetic and stable outcomes.

Conclusion

Although orthognathic surgery is a strong competitor for distraction, the latter is a promising technique for treating various craniofacial defects. By combining our creativity, imagination, orthodontic skill and surgical experience with this basic science, new and exciting applications can be developed.

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Acknowledgements

I would like to extend my gratitude to Dr- Madhur Upadhyay, Dr.Sumit Yadav, Dr.Sukhminder Kaur and Dr. Ruchi Saxena, for editi ng the manuscript and Mr-Abrar for his help in sketching the line diagrams.

Communications

Sameer Patil , MDS Professor, Department of Orthodontics & Dentofacial Orthopedics, KLE'S Institute of Dental Sciences, KLE Academy of Higher Education & Research, J.N.M.e. Campus, Nehru Nagar, Belgaum-590010. e-mail: drsameerpatil@rediffmail.com

References

1. Samchukov ML, Cherkashin AM, Cope JB: Distraction osteogenesis: History and biologic basis of new bone formation. In Lynch SE, Genco RJ, Marx RE, editors; Tissue engineering: applications in maxillofacial surgery and periodontics, Caro l Stream, 111 , 1998; Quintessence.

2. lIizarov GA: The tension-stress effect on the genesis and growth of tissues: Part 1; The influence of stabi li ty of fixation and soft tissue preservation, Cli n Orthop 1989; 238:249-28 1.

3. lIizarov GA: The tension-stress effect on the genesis and growth of tissues: Part II ; The influence of the rate and frequency of distraction, Clin Orthop 1989; 239:263-285 .

4. lIizarov GA: Clinical applicat ions of the tension-stress effect for limb lengthening, Clin Orthop 1990; 250:8.

5. Codivilla A: On the means of lengthening in the lower limbs, the muscles and tissues w hich are shortened through deformity. Am J Orthop Surg 1905; 353-357.

6. Snyder CC, Lev ine GA, Swanson HM, Browne EZ: Mandibular lengthening by grad ual distract ion: Preliminary report. Plast Reconstruct Surg 1973; 51 :506-508.

7. McCarthy JG, Schreiber JS, Karp NS, et al: Lengthening the human mandibl e by gradual distraction ; Plast Reconstr Surg 1992; 89:1-10.

8. M cCarthy JG: The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofac ial microsomia: Clin Plast Surg 1994; 21 :625-631.

9. Polley JW, Figueroa AA: M anagement of severe maxi llary deficiency in childhood and adolescence through distraction osteogenesis with an external adjustable rigid distraction device. J Craniofacial Surg 1997; 8:181 -186.

10. Liou EJW, Huang CS: Rapid canine retraction through distraction of the periodontal ligament. Am J Orthod Dentofacial Orthop 1998; 114:372-82.

224

J Ind Orthod Soc 2006; 39:2 13-229

11 . Iseri H, Bzeizi N, Kisnisci R: Rapid canine retraction using dentoalveolar distraction osteogenesis (Abstract). Eur J Orthod 2001; 23:453.

12. Iseri H, Kisnisc i R, Tuz H , Atlug A: Dentoalveol distraction osteogenesis for rapid orthodontic cani retraction. J Oral Maxillofacial Surg 2002; 60:389-94.

13. Nocini P, Albanese M, Wangerin K, Fior A, Trevi siol L, Kretschmer W: Distraction osteogenesis of the mandible: Evaluation of ca llu s distraction by B-scan ultrasonography. J Cranio Maxillofacial Surg 2002; 30:286-291 .

14. Yasui N, Kojimoto H, Sasaki K, et al. Factors affecting ca llus distraction in limb lengthening. Clin Orthop 1993; 293:55 .

15 . Ueda M, Matsuno M, Sakai K, Hata K: Mechanisms of new bone formation during distraction osteogenesis: A preliminary report. Samchukov ML, Cope JB, Cherkashi n AM, eds. Craniofacia l Distraction Osteogenesis. St. Louis, MO: Mosby; 2001 ; 37-41.

16. Meyer U, MeyerT, Wiesmann HP, Kruse-Losier B, Vollmer D, Stratmann, Joos U: Mechanical tension in distraction osteogenesis regulates chondrocytic differentiation. Int J Oral Maxillofacial Surg 2001; 30:522-530.

17. Rachmiel A; Mandibular distraction osteogenesis using extra ora l and intra oral devices: Samchukov ML, Cope JB , Cherk ashin AM, eds: Crani ofac ial Distraction Osteogenesis. St. Louis, MO : Mosby; 2001; 225-229.

18. Samchukov ML, Cope JB, Cherkash in AM: Introduction to distraction osteogenesis. Samchukov ML, Cope JB, Cherkashin AM , eds; Craniofacial Di st ract io n Osteogenes is. St. Louis: MO; Mosby; 2001; XXVII­XXXVI.

19. De Bastiani G, Aldegheri R, Renzi-Brivio L, Trivella G: Limb lengthening by distraction of the ep iphyseal plate: a comparison of two technique in rabbit. J Bone Joint Surg 1986; 68B:545 .

20. Guerrissi J, Ferrentino G, Margulies D, Fiz D: Lengthening of the mandible by distraction osteogenesis: Experimental work in rabbits. J Craniofacial Surg 1994; 5:313.

21. Fisher E, Staffenberg DA, M cCart hy JG , et al . Histopathologic and biochemical changes in the muscles affected by distraction osteogenesis of the mandible. Plast Reconstr Surg 1997; 99:366.

22 . Simpson AHRW, Williams PE, Kyberd P, et al. The response of muscle to leg lengthening. J Bone Jo int Surgery 1995; 77:630.

23. M akarov M, Samchukov ML, Cope JB, Muirhead D: The effect of gradual traction on skeletal muscles. Samchukov ML, Cope JB, Cherkashin AM. Craniofac ial Distraction Osteogenesis. St. Louis, MO: Mosby: 2001; 75-88.

24. Karp NS, Thorne CH, M cCarthy JG, Sisson GA Sr: Bone lengthening in the craniofacial skeleton. Ann Plast Surg 1990; 24:23 1.

25. Michieli S, Miotti B: Lengthening of mandibular body by gradual surgical orthodontic distraction. J Oral Surg 1977; 35:187.

//

/Lu~ : ...

26. Block MS, Daire J, Stover J, Matthews M: Changes in the inferior alveo lar nerve fo llowing mandibular lengthening in the dog usi ng distraction osteogenesis. J Ora l Maxillofac Surg 1993; 51 :652.

27. M akarov M , Harper R, Cope JB , Samchukov ML : Evaluation of inferior alveola r nerve fu nct ion during distraction osteogenesis. J O romaxi llofac ial Surg 1998; 56: 141 7-1423.

28. Hu J, Tang Z, Wang D, Buck ley M : Changes in the inferior alveolar nerve after mandibular lengthening w ith different rates of distraction . J Ora l Maxillofacial Surg 200 1; 59: 104 1-1 045.

29. Whitesides L, Meyer R: Effect of distraction osteogenesis on the severely hypoplast ic mandibl e and inferior alveo lar nerve funct ion. J Ora l Maxillofacial Surg 2004; 62:292-297.

30. Row NM, Mehrara BJ, Luchs JS, Dudziak ME, Steenbrech OS: Angiogenesis during m andibul ar distraction osteogenesis. Ann Plast Surg 1999; 42(5);470-5.

31. Tencate AR: Repair and regeneration of dental tissue: In oral histology: Development, structure, function , ed 5, St. Louis M osby 1998.

32. Bell WH, Genzalec M , Samchukov ML, Guerrero CA: Intraoral w idening and lengthening of the mandible by distraction osteogenesis. J Oral Maxillofacial Surg 1999; 57:548.

33. Samchukov ML, Cope JB: The effect of gradual traction on periodontal ligament. Samchukov ML, Cope JB, Cherkashin AM. Craniofac ial Distraction Osteogenesis. St. Louis, MO: Mosby: 2001; 110-117.

34. Block MS, Chang A, Akin R, Gottsegen GB: Skeletal and dental rel apse after m ax ill ary advancement using distraction osteogenesis. J Oral M axillofacial Surg 1996; 54:94.

35. Block MS, Akin R, Chang A, et al: Skeletal and dental movements after anterior maxillary advancement using implant-supported distraction osteogenesis in dogs. J Oral Maxillofacial Surg 1997; 55:1433.

36. Block MS, Cervini D, Chang A, Gottsegen GB: Anterior maxi llary advancement using tooth supported distraction osteogenesis. J Oral M axi llofacia l Surg 1995; 53 :561.

37. M ehrara BJ, Rowe NM, Steinbrech DS, Dudzi ak ME, Saadeh PB, M cCarthy JG, Gittes GK, Longaker MT: Rat mandibul ar distract ion osteogenesis II . Molecul ar analysis of transforming growth factor b-1 and osteocalci n gene express ion. Pl ast Reco nst ru ctive Surg 1999; 103:536-547.

38. Warren SM, Mehrara BJ, Steinbrech DS, Paccione MF, Greenwald JA, Spector JA, Longaker MT. Rat mandibular distraction osteogenesis Part III. Gradual distraction versus acute lengthening. Plast Reconstruct Surg 2001; 107:441-453.

39. Contasti G, Rodriguez AM, Guerrero CA: Orthodontics in intra oral mandibular distraction osteogenesis. Samchukov ML, Cope JB, Cherkashin AM. Craniofacial Distraction Osteogenesis. St. Louis; MO: Mosby; 2001 ; 75-88.

Sethi et al

40. Orhan M , Malkoc S, Usumez S, Uckan S: Mandibular symphyseal distraction and its geometrica l evaluation : Report of a case. Angle Orthod 2003; 73: 194-200.

41 . Contasti G, Guerrero C, Rodriguez AM, Legan H: Mandibular widen ing by distraction osteogenesis. )CO 2001; VoI.XXXV, 3: 165-173.

42. Guerrero CA, Be ll WH, Contasti GI, Rodriguez AM: Mandibular widen in g by intraora l distraction osteogenesis. British Journal of O ral and Maxillofacial Su rg 1997; 35:383-392.

43. Molina F, Ortiz Monasterio F: M andibul ar elongation and remodeling by distraction. A farewell to major osteotomies. Plast Reconstr Surg 1995; 96:825-842.

44 . Constantino PD, Buchbonder D: M andibular distraction osteogenes is types, app li cat ions and indi cat ions. J Craniofacia l Surg 1996; 7:404.

45. Aro nson J, H arr ison BH, Stewart CL, H arp JH : The histology of distraction osteogenes is using different external fixations. Clin Orthop 1989; 241:106.

46. Gateno J, Kim K, Lalani Z, Teichgraeber J, Liebschner M, Lemoine J, Xia J: Biomechanical evaluation of the pins of a mandibular external distractor. J Oral Max illofacial Surg 2004; 62:1259- 1263.

47. Hurmerinta K, Hukki J: Vector contro l in lower jaw distraction osteogenes is usin g an ex trao ral multidirectional device. Journal of Craniomaxillofacial Surg 2001; 29:263-270.

48. H ansen P: Treatm ent planning and orthodontic m anage ment of patients undergoin g mandibul ar distraction osteogenesis. Samchukov ML, Cope JB, Cherkashin AM: Craniofacial distraction osteogenesis. St. Louis Mosby: 2001; 156-167.

49. Rachmi el A, M anor R, Peled M , Laufer D: Intraoral distraction osteogenesis of the mandible in hemifac ial microsomia. Journal Oral and M axillofacial Surgery 2001; 59:728-733.

50. Ayoub A, Duncan C, Mclean G, Moos K, Chibbaro P: Response of patients and families to lengthening of the facial bones by extraoral d istract ion osteogenesis. A rev iew of 14 patients. British Journal of Oral and M axillofac ial Surg 2002; 40:397-405 .

51 . Bueno P, Villa E, Carreno A, Naval L, Sastre J, Manzanares R, Gonzalez F: Intrao ral m andibular distrac tion osteogenesis: special attention to treatment planning. Journal Craniomaxillofacial Surg 2001 ; 29:254-262 .

52. Guerrero C, Bell W, Contasti G, Rodriguez A: Mandibular w idening by intraoral distraction Osteogenesis. British Journal of Oral and Maxi llofacial Surgery 1997; 35:383-392.

53 . Mussa R, Smith J: Mandibular symphyseal distraction osteogenesis. )CO 2003; XXXVII (1): 13-18.

54. Gonzalez M, Be ll W , Guerrero C, Buschang P, Samchukov M : Positional changes and stability of bone segments duri ng simultaneous bi lateral mandibu lar lengthening and widening by distraction . British Journal of Oral and M axillofacial Surgery 2001; 169-178.

225

s 55 . Bueno Rubio Pilar, Naval Luis, Francisco Rodriguez,

Diez Jose, Gonzalez D: Internal distraction osteogenesis with a unidirectional device for reconstruction of mandibular segmental defects. Journal Oral Maxillofacial Surgery 2005; 63 :598-608.

56. Losken H: Planning of m and ibular distraction. Samchukov ML, Cope JB, Cherkashin AM; Craniofacial Distraction Osteogenesis. St. Louis; MO: Mosby; 2001 , 168-175.

57. Tae K, Kang K, Kim S: Unilateral mandibular widening with distraction osteogenesis. Angle Orthod 2005 ; 75: 1053-1060.

58. Breuning K, Strijen P, Andersen B, Tuinzing D: The overbite and intraoral mandibular distraction osteogenesis. Journal of Craniomaxillofacial Surgery 2004; 32:119-125.

59. Klein C: Extraoral mandibular distraction osteogenesis using the Frankfurt modular distraction system. Samchukov ML, Cope JB, Cherkashin AM; Craniofacial Distraction Osteogenesis. St. Louis; MO: Mosby 2001 ; 187-195 .

60. Cohen, Steven R, Holmes R: Internal Le fort III distraction with biodegradable devi ces. Journal of Craniofacial Surgery 2001; 12(3):264-272.

61. Burstein F, William J, Hudgins R, Graham L, Gerald, Paschal M , Simm SC: Single stage craniofacial distraction using resorbable devices. Journal of Craniofacial Surgery 2002; 13(6):776-782.

62. Burstein F, William J: Mandibular distraction osteogenesis in Pierre Robin sequence; App lication of a new internal single stage resorbable device. Plastic and Reconstr Surg 2005; 115(1):61-67.

63. Samchukov ML, Cope JB, Harper RP, Ross JD. Biomechanical considerations of mandibular lengthening and widening by gradual distraction using a computer model. Journal Ora l and Maxillofacial Surg 1998; 56:51-59.

64. Samchukov ML, Cope JB, Cherkashin AM: The effect of sagittal orientation of the distractor on the biomechanics of mandibular lengthening. J oral Maxillofacial Surg 1999; 5:1214-1221.

65 . Grayson B, McCormick S, Santiago PE, McCarthy JG : Vector of device placement and trajectory of mandibu lar distraction. J Craniofacial Surg 1997; 8:473-482.

66. Diner PA, Kollar E, Martinez H, Vazquez MP: Intraoral distraction for mandibular lengthening: A technical innovation . J Craniomaxi llofacial Surg 1996; 24:92-95 .

67. Diner PA, Kollar E, Martinez H, Vazquez MP: Submerged intraoral device for mandibular lengthening . J Craniomaxillofacial Surg 1997; 25:116-123.

68. Diner PA, Tomat C, Soupre V, Martinez H, Vazquez MP.

226

Intraora l mandibular distraction : indications, technique and long term results. Ann Acad Med Singaport 1999; 28:634-641.

69 .

70.

71.

72 .

73.

74 .

75.

76.

77.

78.

79 .

80.

81.

82.

83.

84.

J Ind Orthod Soc 2006; 39:213-229

Heggie A, Scott PA: Distraction osteogenesis in a patient with micrognathia and a rare facial clefting syndrome. Aust Orthod J 1998; 15:200-205. Huang CS, K6 WC, Lin WY, Liou EJ, Hong KF, Cben YR: Mandibular lengthening by distraction osteogenfs is in children - a one year fo llow up study. Cleft Palate Craniofac Journal 1999; 36:269-274. Juenger TH, Klingmueller V, Howaldt HP: Application of ultra sound in ca llus distraction of the hypoplastic mandible: an additional method for the fol low up. J Craniomaxillofacial Surg 1999; 27:160-167. Klein C, Howaldt HP : Correction of mandibular hypoplasia by means of bidirectional ca llus distraction. J Craniofacial Surg 1996; 7:258-266. Klein c, Howaldt HP : Mandibular distraction osteogenesis as first step in the early treatment of severe dysgnathia in childhood. J Orofac Orthop 199&; 57:46-54 . Losken HW, Patterson GT, Lazarou SA, Whitney T. Planning mandibular distraction: Preliminary report. Cleft Palate Craniofacial J 1995; 32 :71-76. McComick SU, Grayson BH, McCarthy JG, Staffenberg D: Effect of mandibular distraction on the temporomandibular joint Part 2: Clinical study. J Craniofacial Surg 1995; 6:364-367. Molina F: Combined maxillary and mandibular distraction osteogenesis. Semin Orthod 1999; 5:41-45. Polley JW, Breckler Ramasastry and Figueroa AA. Simu ltaneous distraction osteogenesis and microsurgical reconstruction for facial asymmetry. J Craniofacial Surg 1996; 7:469-472. Polley JW, Figueroa AA: Distraction osteogenesis: Its app li cation in mandibular deformities in hemifacial microsomia. J Craniofacial Surg 1997; 8:422-430. Rachmiel A, Levy M, Laufer D: Lengtheni ng of mandible by distraction osteogenesis: report of cases . J Oromaxillofac Surg 1995; 53:838-846. Stucki Mc Cormick SU, Mizrahi RD, Fox RM: Distraction osteogenesis of the mandible using a submerged intra oral device; a rep9rt of three cases. J Oral Maxillofacial Surg 1999; 57:1f 2-1 ~8. Sugihara Y, Kawf,h:ir;na K, 19awa H, Ohura T, Yamamura M , Ohata N : "'. ' dibular lengthening by gradua l distraction in huns. Eur J Plast Surg 1995; 18:7-10. Takato T, Harii K, Hirabayashi S, Komuro Y, Yonehara Y, Susami T: Mandib}Jlar lengthening by gradual distraction: analysis using accurate skull replicas. Br J Plast Surg 1993; 46:686-693. Tharanon W , Sinn DP: Mandibular distraction osteogenesis with multidirectional extra oral distraction device in hemifacial microsomia patients: Three dimensional treatment planning, prediction tracings, and case outcomes. J Craniofacia l Surg 1999; 10:202-213. Santler G, Karcher H, Mossbock R: Simultaneous orbita l expansion and intra oral distraction osteogenesis of upper and lower jaws in a patient with hemifacial

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microscomia. Journal Craniomaxillofacial Surg 2003; 31 :228-233.

85 . Tehranchi A , Behnia H: Treatment of mandibular asymmetry by distraction osteogenesis and orthodontics: A report of 4 cases. Angle Orthod 2000; 70: 165-174.

86. Meazzini M , Mazzol eniF, Canzi G, Bozzetti A : . Mandibular distraction osteogenesis in hemifacial microsomia : Long term follow up. Journ al of Craniomaxillofacial Surg 2005; 33:370-376.

87. Block MS, Otten J, Mclaurin D, Zoldus J: Bifocal distraction osteogenesis for mandibular defect healing: Case reports. J Oral Maxillofacial Surg 1996; 54:1365-1370.

88. Carter LC, Aguire A, Boyd B, Delacure MD: Primary Leiomyosarcoma of the mandible in a 7 year old girl : Report of a case and review of the literature. Oral Surg, Oral Med, Oral Pathol , Oral Radiol, Endod 1999; 87:477-484.

89. Sawaki Y, Hagino H, Yamamoto H, Veda M. Trifocal distraction osteogenesis for segmental mandibular defect: a technical innovation. J Craniomaxillofacial Surg 1997; 25:310-315.

90. Shivyrkov MB, Sumarokov DD, Shamsudinov AH: Osteoplasty of the mandible by local tissues. Journal Craniomaxi lIofacial Surg 1995; 23:377-381.

91. Shvyrkov MB, Shamsudinov AH , Sumarokov DD, Shivyrkova II: Non-free osteoplasty of the mandible in maxillofacial gunshot wounds : Mandibular reconstruction by compression osteodistraction. Br J Oral Maxillofacial Surg 1999; 37:261-267.

92 . Stucki-McCormick SU: Reconstruction of the mandibular condyle using transport distraction osteogenesis. J Craniofacial Surg 1997; 8:48-53.

93. Holmes SB, Lloyd T, Coghlan KM, Newman L: Distraction osteogenesis of the mandible in the previously irradiated patient. J Oral Maxillofacial Surg 2002; 60:305-309 .

94. Klesper B, Lazar F, Siebegger M, HiddingJ, Zoller J. Vertical distraction osteogenesis of fibula transplants for mandibular reconstruction - a preliminary study. Journal Craniomaxillofacial Surg 2002; 30:280-285 .

95. Raghoebar G, Jansma J, Vissink A, Roodenberg LN . Distraction osteogenesis in the irradiated mandible: A case report. J Cranio Maxillofacial Surg 2005; 33 :246-250.

96. Fukuda M, lino M, Yamaoka K, Ohnuki T, Nagai H, Takahashi T: Two stage distraction osteogenesis for mandibular segmental defect. J Oral Maxillofacial Surg 2004; 62:1164-1168.

97. Ying BJ, Hu J, Zhu S, Brain TW: Reconstruction of mandibular symphyseal defects by trifocal distraction osteogenesis : An experimental study in Rhesus. J Oral Maxillofacial Surg 2006; 35:159-164.

98. Girod A, Roger T, Breton P, Bouletreau P: Experimental study of mineralization in mandibular bone distraction with irradiation during consolidation phase. J Craniomaxillofacial Surg 2005; 33:386-394.

Sethi et al

99 . Kondoh T, Hamada Y, Kamei cK, Seto K: Transport distraction osteogenesis following marginal resection of the mandible. J Oral Maxillofacial Surg 2002; 31 :675-676.

100. Uckan S, Dolanmaz D, Kalayci A, Cilasun U: Distraction osteogenesis of basal mandibular bone for reconstruction of the alveolar ridge. British J Oral Maxillofacial Surg 2002; 40:393-396.

101. Dessner S, Razdolsky Y, EI-Baily, Evans CA: M andibular lengthening using preprogrammed intraoral tooth borne distraction devices. J Oral Maxillofacial Surg 1999; 57 :1318-1322.

102. Mattick CR, Chadwick SM, Morton ME: Mandibular advancement using an intraoral osteogenic distraction technique: A report of three clinical cases. Journal of Orthodontics 2001; 28:105-114.

103. Breuning K, Strijen P, Andersen B, Tuinzing D: Duration of orthodontic treatment and mandibular lengthening by means of distraction or bilateral sagittal split osteotomy in patients with Angle class II malocclusions. Am J Orthod Dentofacial Orthop 2005; 127:25-29.

104. Karacay S, Akin E, Okcu K, Bengi 0 , Atlug A: Mandibular distraction with MD-DOS device. Angle Orthod 2005; 75): 685-693 .

105 . Triaca A, Antonini M, Minoretti R, Merz B: Segmental distraction osteogenesis of anterior alveolar process. J Oral and Maxillofacial Surg 2001; 59:26-34.

106. Carls FR, Sailer HF: Seven years clinical experience with mandibular distraction in children. J Craniomaxillofacial Surg 1998; 26: 197-208.

107. Dean A, Alamillos F: Mandibular distraction in temporomandibular joint ankylosis. Plast Reconstr Surg 1999; 104:2021-2031.

108. McCarthy JG, Williams JK, Grayson BH, Crombie JS: Controlled multi planar distraction of the mandible: device development and clinical application. J Craniofacial Surg 1998; 9:322-329.

109. Papageorge MB, Apostolidis C: Simultaneous mandibular distraction arthroplasty in a patient with temporo mandibular joint ankylosis and mandibular hypoplasia. Journal Oral and Maxillofacial Surg 1999; 57:328-333.

110. Roth DA, Gosain AK, McCarthy JG, Stracher MA, Lefton DR, Grayson B: A C.T. scan technique for quantitative volumetric assessment of the mandible after distraction osteogenesis. Plast Reconstr Surg 1997; 99:1237-1250.

111. Watzinger F, Wanschitz F, Rasse M, Millese W, Schopper CH, Kremser J, Birkfellner W, Sinko K, Ewers R: Computer aided surgery in distraction osteogenesis of the maxilla and mandible. In J Oral Maxillofac Surg 1999; 28: 171-175.

112. Rao K, Kumar S, Kumar V, Singh A, Bhatnagar S: The role of simultaneous gap arthroplasty and distraction osteogenesis in the management of temporomandibular joint ankylosis with mandibular deformity in children. Journal of Craniomaxillofacial Surg 2004; 32:38-42.

113. Kewitt GF, Van Sickels JE: Long term effect of mandibular midline distraction osteogenesis on the status of the TMJ,

227

teeth, periodontal structures and neurosensory function . J Oral Maxillofacial Surg 1999; 57:1419-1425 .

114. Weil TS, Van Sickels JE, Payne CJ: Distraction osteogenesis for correction of transverse mandibular deficiency: a preliminary report. J Oral Maxillofacial Surg 1997; 55:953-960.

115. Whitman DH, Connaughton B: Model surgery prediction for mandibular midline distraction osteogenesis. Int J Oral Maxillofacial Surg 1999; 28:421-423.

116. Mommaerts M, Polsbroek R, Santler G, Correia P, Abeloos J, Ali N: Anterior transmandibular osteodistraction : Clinical and model observations. J Craniomaxillofacial Surg 2005; 33:318-325.

117. Duran I, Malkoc S, Iseri H , Tunali M , Tosun M, Kucukkolbasi H: Microscopic evaluation of mandibular symphyseal distraction osteogenesis. Angle Orthod 2006; 76:369-374.

118. Bell WH, Harper RP, Gonzalez M, Cherkashin AM, Samchukov ML: Distraction osteogenesis to widen the mandible. British Journal of Oral and Maxillofacial Surg 1997; 35:11-19.

119. King J, Wallace J, Scanlan D: A new appliance for mandibular widening by distraction osteogenesis. )CO 2001; Vol. XXXV(ll): 666-672.

120. Conley R, Legan H: Mandibular symphyseal distraction osteogenesis: Diagnosis and treatment planning considerations. Angle Orthod 2003; 73: 3-11 .

121 . King J, Wallace J, Scanlan D: Precision distractor placement with a custom-made index. )CO 2002; Vol. XXXVI (2): 88-91.

122. Chin M, Toth BA: Distraction osteogenesis in maxillofacial surgery using internal devices: A review of five cases. J Oral Maxillofacial Surg 1996; 54:45-54.

123. Codivilla A: On the means of lengthening in the lower limbs the muscles and the tissues which are shortened by deformity. Am J Orthop Surg 1905; 353-357.

124. Cohen SR, Rutrick PE, Burstein: Distraction osteogenesis of the human craniofacial skeleton. Initial experience with a new distraction system. J Craniomaxillofacial Surg 1995; 6: 368-374.

125. McCarthy JG. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 1994; 21 :625-631.

126. Hukki J, Suvanto T, Hurmerinta K, Sahlin P: Pinhole osteotomy in distraction osteogenesis: A technical note. J Craniomaxillofacial Surg 2002; 30:144-147.

127. Chigurupati R, Myall R: Airway management in babies with micrognathia: The case against early distraction. J Oral Maxillofacial Surg 2005; 63:1209-1215.

128. Kocabalkan 0, Lebelbicioglu G, Eck Y, Enacar A: Repeated mandibular lengthening in Treacher Collins syndrome: A case report. Int J Oral Maxillofacial Surg 1995; 24: 406-408.

129. Moore MH, Guzman Stein G, Proudman TW, Abbott AH, Neterhway DJ, David DJ: Mandibular lengthening by distraction for airway obstruction in Treacher Collins syndrome. J Craniofacial Surg 1994; 5:22-25.

228

J Ind Orthod Soc 2006; 39:213-229

130. Williams JK, Maull D, Grayson BH, Longaker MT, M cCarthy JG: Early decannulation with bilateral mandibu lar distraction for tracheostomy dependent patients. Plast Reconstr Surg 1999; 103:48-59.

131 . Arun T, Kayhan F, Kiziltan M: Treatment of condylar hypoplasia with distraction osteogenesis: A case report. Angle Orthod 2002; 72(4):371-376.

132. Habal MB: New bone formation by biological rhythmic distraction. J Craniofacial Surg 1994; 5:344-347.

133. Havlik R, Bartlett SP: Mandibular distraction lengthening in the severely hypoplastic mandible: A problematic case with tongue aplasia. J Craniofacial Surg 1994; 5:305-312.

134. Hollier LH, Kim JH, Grayson B, McCarthy MG: Mandibular growth after distraction in patients under 48 months of age. Plast Reconstr Surg 1999; 103:1361-1370.

135. Steinbacher D , Kaban L, Troulis M : Mandibular advancement by distraction osteogenesis for tracheostomy dependent children with severe micrognathia. J Oral Maxillofacial Surg 2005; 63:1072-1079.

136. Cohen SR, Simms C, Burstein FD: Mandibular distraction osteogenesis in the treatment of upper airway obstruction in children with craniofacial deformities. Plast Reconstr Surg 1998; 10(2):312-318.

137. Howlett C, Stavropoulos MF, Steinberg B. Feeding complications in a six week old infant secondary to distraction osteogenesis for airway obstruction: A case report. J Oral Maxillofacial Surg 1999; 57:1465-1468.

138. Steinberg B, Fattahi T: Distraction osteogenesis in management of pediatric airway: Evidence to support its use. Journal of Oral Maxillofacial Surg 2005; 63:1206-1208.

139. Aizenbud DR, Pillar G, Srouji S, Peled M: Bilateral mandibular distraction for patients with compromised airway analysed by three dimensional CT. International Journal of Oral and Maxillofacial Surg 2005; 34:9-18.

140. Gaggl A, Schultes G, Karcher H: Distraction implants-A new operative technique for alveolar ridge augmentation. J Craniomaxillofacial Surg 1999; 27:214-221.

141. Urbani G, Lombardo G, Santi E, Consolo U: Distraction osteogenesis to achieve mandibular vertical bone regeneration : A case report. I nt J Periodontics & Restorative Dentistry 1999; 19:321-331.

142. Garcia A, Martin M, Vila P, Rey J: A preliminary morphologic classification of the alveolar ridge after distraction osteogenesis. J Oral Maxillofacial Surg 2004; 62:563-566.

143. Laster Z, Rachmiel A, Jensen 0: Alveolar width distraction osteogenesis for early implant placement. J Oral Maxillofacial Surg 2005; 63:1724-1730.

144. Mazzonetto R, Maurette M: Radiographic evaluation of alveolar distraction osteogenesis: Analysis of 60 cases. J Oral Maxillofacial Surg 2005; 63:1708-1711.

~

145. Saulacic N, Martin M, Vila P, Garcia A: Relapse in alveolar distraction osteogenesis: An indication for overcorrection. J Oral Maxillofacial Surg 2005; 63:978-981.

146. Hwang S, Jung JG, Jung JU, Kyung S: Vertical alveolar bone distraction at molar region using lag screw principle. J Oral Maxillofacial Surg 2004; 62:787-794.

147. Garcia A, Martin M, Vila P, Maceiras J: Minor complications arising in alveolar distraction osteogenesis. J Oral Maxillofacial Surg 2002; 60:496-501 .

148. Rodriguez JG, Dogliotti P: Mandibular distraction in glossoptosus micrognathic association: Preliminary report. J Craniofacia l Surg 1998; 9:12-129.

149. Perrott D, Berger R, Vargervik K, Kaban Leonard. Use of a skeletal distraction device to widen the mandible. J Oral Maxillofacial Surg 1993; 435-439.

150. Kollar EM, Diner PA, Vazquez MP; Accart G; Pirollo M: Bone distraction using an external fixator : a new mandibular lengthening technique - A preliminary study apropos of 2 cases of chi ldren with mandibular hypoplasia. Rev Stomatol Chir Maxillofac 1994; 95:411-416.

151. Muhonen A, Peltomaki T, Hinkka S, Happonen RP: Effect of mandibular distraction osteogenesis on temporomandibular joint after previous irrad iation and hyperbaric oxygenation. J Oral Maxillofacial Surg 2002; 31 :397-404.

152. Stucki McCormick SU, Fox RM , Mizrahi RD: Reconstruction of a neocondyle using transport distraction osteogenesis. Semin Orthod 1999; 5: 59-63.

153. Strijen PJ, Breuning KH, BeckingAG, Tuinzing DB: Condylar resorption following distraction osteogenesis: A case report. J Oral Maxillofacial Surg 2001; 59:1104-1107.

154. Klein C, Howaldt HP: Lengthening of the hypoplastic mandible by gradual distraction in childhood - a preliminary report. J Craniomaxillofacial Surg 1995; 23:68-74.

155. Kisnisci RS, Fowel SD, Epker BN: Distraction osteogenesis in Silver Russel syndrome to expand the mandible. Am J Dentofacial Orthop 1999; 116:25-30.

156. Corcoran J, Hubli EH, Salyer KE: Distraction osteogenesis of costochondral neomandibles : a clinical experience. Plast Reconstr Surg 1997; 100:311 -317.

157. www.emedicine.com/entltopic765.htm_87k 158. Contasti G, Rodriguez AM, Guerrero C: Orthodontics in

intra oral mandibular distraction osteogenesis. Samchukov ML, Cope JB , Cherkashin AM; eds: Craniofacial distraction osteogenesis. St. Louis; MO; Mosby 2001; XXVII-XXXVI.

159. Burstone C: Soft tissue cephalometric analysis for orthognathic surgery. Journal Oral Surg 1980; 38:744-751.

160. Ricketts RM: The value of cephalometrics and computerized technology. Angle Orthod 1972; 42:179.

161. White LW: The clinical use of occlusograms. J Clinical Orthod 1982; 16:92-103.

162. Breuning K, Strijen P: Orthodontic indications for mandibular distraction. Samchukov ML, Cope JB,

Sethi et al

Cherkashin AM: Craniofacial distraction osteogenesis. St. Louis; M: Mosby; 2001; 278-285.

163. CopeJB, Harper RH, Samchukov ML. Experimental tooth movement through regenerate alveolar bone. A pilot study. Am J Orthod 1999; 116:501-505.

164. Liou EJ, Figueroa AA, Polley JW. Rapid orthodontic tooth movement into newly distracted bone after mandibular distraction osteogenesis in a cani ne model. Am J Orthod Dentofacial Orthop 2000; 117: 391-398.

165. Liou EJW, Polley JW, Figueroa AA: Distraction osteogenesis: the effects of orthodontic tooth movement on distracted mandibular bone. J Craniofacial Surg 1998; 9: 564-571 .

166. Nakamato N, Nagasaka H, Daimaruya T, Takahashi I, Sugawara J, Mitani H: Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs. Am J Orthod Dentofacial Orthop 2002; 121 :385-395.

167. Hagi no H, Yashihim S, Uedo M: The fate of developing teeth in mandibular lengthening by distraction: an experimental study. Journal of Cranio Maxillofacial Surg 2001; 29:94-99.

168. Koenig WR, Olsson AB, Pensler JM: The fate of developing teeth in facial trauma: Tooth buds in the line of mandibular fractures in children. Ann Plast Surg 1994; 32 : 503-505.

169. Troulis J, Perrott DH, Kaban LB: Endoscopic mandibular osteotomy and placement and activation of a semiburied distractor. J Oral Maxillofacial Surg 1999; 57:1110.

170. Castano FJ, Troulis MJ, Glowacki J, et al. Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible. J Oral Maxillofacial Surg 2001; 59:302.

171. McTavish J, Marucci DD, Bonar SF, et al. Does the sheep mandible relapse following lengthening by distraction osteogenesis? J Oral and Maxillofacial Surg 2000; 28:251-257.

172. SumitYadav, Sameer Patil, KM Keluskar: Canine distraction -A review. J Ind Orthod Soc 2005; 38:212-217.

173. Tavakoli K, Walsh WR, Bonar F, Smart R, Wulf S, Poole MD. The role of latency in mandibular osteodistraction. J Craniomaxillofacial Surg 1998; 26: 209-219.

174. Schendel SA, Epker BN: Results after mandibular advancement surgery: An analysis of 87 cases. J Oral Surg 1980; 38:265.

175. Cope JB, Samchukov ML, Cherkashin AM: Mandibular distraction osteogenesis: a historical perspective and future directions. Am J Orthod Dentofac Orthop 1999; 115:448-460.

176. Strijen PJ, Breuning KH, Becking AG, Tuinzing DB. Stability after distraction osteogenesis to lengthen the mandible. Results in 50 patients. J Oral Maxilofac Surg 2004; 62: 304-307.

177. Primrose AC, Broadfoot E, Diner PA, Molina F, Moos KF, Ayoub AF. Patients responses to distraction osteogenesis: a multi-centre study. IntJ Oral & Maxillofacial Surg 2005; 34: 238-242.

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