This document summarizes distraction osteogenesis (DO), which is a process where new bone is formed between bone segments that are gradually separated. DO involves three phases: a latency phase, distraction phase where the bone is gradually separated, and consolidation phase where the new bone mineralizes. It discusses the history and applications of DO, including for lengthening of long bones and the mandible. Key advantages are that it allows for larger movements than traditional bone grafts and avoids prolonged fixation. Potential complications include non-compliance, pain, premature consolidation, and neurological damage.

1. Distraction osteogenesis (DO)
MATTICK 2000
 Distraction osteogenesis (DO) is a biologic process of new bone formation between bone
segments that are gradually separated by incremental traction.
 This controlled distraction, generates new bone within the distracted gap. So in a way, it is an
in-vivo bone tissue engineering
History
 Alessandro Codivilla in 1905, was the first to perform DO surgery. He published a case report
of femoral extension by applying axial forces of distraction.
 Distraction osteogenesis for bone lengthening was an accidental discovery off Ilizarov when
he observed callus formation in a patient who had mistakenly distracted his frame instead of
compressing it.
 The Russian surgeon, Gavriil Ilizarov, who pioneered the biological principles of bone and soft
tissue regeneration and popularized the technique of distraction osteogenesis, (Ilizarov,
1989).
 McCarthy from United States, reported the first craniofacial DO in humans and Guerrero was
the first to use inta-oral device to widen mandibular arches.
Sequence of DO
I. Osteotomy
• Trigger fracture healing will initiate: Angiogenesis, fibrogenisis, Osteoinduction &
Osteoconduction
a. Latency phase (3 to 7 days)
• Phase immediately following the osteotomy,
• Reparative callous formation
b. Distraction phase
• Gradual distraction at a rate of ~1.0 mm day
c. Consolidation phase (6-10 weeks)
• Distraction is ceased
• Mineralization and Corticalisation. The bone produced is less denseand of lower volume than
the ‘original’ bone, but is believed to have equivalent growth potential.

2. d. Remodeling Phase
• Continues approxiamtely for a year after completion
Histologically distinct stages of DO
Normally, four histologically distinct stages of bone repair are observed:
1. an inflammatory phase, immediately following an osteotomy, blood fills the space between
the separated bone segments, and an inflammatory cell infiltrate is observed. This
inflammatory stage represents an acute response to the injury and lasts several days. If DO
started at this stage, then the result is decreased bone formation, often with cartilaginous
elements present, and decreased mechanical strength of the newly created bone. An
important consideration in treatment planning for mandibular lengthening is how the bone
cuts will be coordinated with placement of the distractor. Some recommend:
 Making the cortectomy, placing the distractor, and then completing the osteotomy with the
distractor in place. With that approach, the distractor may hinder completion of the
osteotomy.
 First cortectomies followed by completion of the osteotomy through activation of the device
 Completion of the osteotomy and placing the distractor after completing the initial incision
and dissection, doing the buccal cortectomy, removing the distractor and completing the
osteotomy, and then finallyplacing a distractor with the originalrelationships of the segments
intact.
2. The initialhematoma is then replaced by granulation tis sue. Largenumbers of fibroblasts and
mesenchymal stem cells arc recruited to the region, and synthesis of type 1 collagen is seen
within the fracture zone. In addition, there is a vascularresponse marked by formation of new
capillaries. These fibrous structures create a soft callus that bridges across the fractured bone
segments. DO should start at this stage. The blood supply duitng DO increased *7 times.
The cellular basis for induction of regeneration under stretching is that:
• Any cells under pressure will demonstrates catabolic state where it starts degeneration by
releasing of tissueresorbing factors. This in the pressure side of orthodontic tooth movement.
• Any cells under stretch will demonstrates anabolic state where it starts regeneration by
releasing of tissue forming factors. This is the stretch phase in DO.

3. There are two important variables in the activation:
I. Rate, or the amount of distraction per day, and rhythm, or how frequently the device is
activated. If the rate of distraction is too small, there is a risk of premature consolidation. On
the other hand, too great a rate of distraction may place undue stress on the soft callus,
resulting in thinning of alldimensions in the mid-portion of the regenerate and an "hourglass"
at the distraction site. This can be likened to the effect of pulling taffy apart
II. With regard to rhythm, constant activation probably would be ideal, although this is not
possible with current devices.
a. Ilizarov felt that rhythm was critical to osteogenic activity. His recommendation was for 0.25
mm four times a day.
b. In the majority of maxillofacial cases described in the literature, the most common protocol
is 0.5 mm increments twice daily. Clinical experience suggests that activation of more than
0.5 mm at a time results in a marked increase in pain, from more aggressive stretching of the
periosteum and musculature.
c. In some instance activation of 0.5 mm may result in complaints of pain by the patient, and in
such cases distraction at a rate of 0.25 mill four times daily is an acceptable alternative.
d. Due to the fast healing response of infants, distraction can be initiated immediately, at the
rate of 1.5 mm per day in three 0.5 mm activations.
e. During the stabilization phase the use of orthodontic elastics guides the dentition, and is also
thought to aid vectorization and ‘mould’ the developing regenerate.
f. One of the primary considerations in treating hypo plastic mandibles is the extent to which
lengthening of the ramus versus the body is desired. Proportional analysis is one way to
establishthis. The average relationship of ramus height (Co-Go) to body length (Go-Gn) is 5:7;
the relationship of the maxillary jaw length (ANS-PNS) to mandibular body length is 2:3.
Another guideline is that the anterior cranial base length (S-N) is slightly less than (2 to 3 mm)
the mandibular body length.
g. Weekly panoramic radiographs arc taken until the distractor is fully activated
3. Approximately 2 week; following the initial injury, there is a progressive mineralization of the
soft callus, resulting in formation of a hard callus. The hard callus is composed of immature
bone. In the finalphase of fracture repair, there is extensiveremodeling of this "woven" bone,
and the normal lamellar architecture is regained. If DO started at this stage the distraction

4. device may be unable to further separate the bony segments. In the Case of large
advancements. additional stabilization can be obtained from a brief period of
maxillomandibular fixation during the consolidation phase. With internal distraction devices
in children, a consolidation period of 4- months is recommended before the distractor is
removed, bur in older patients or patients with a compromised physical condition, 6 months
may be a minimal, and in some cases (e.g., multiple previous operations, patient who
smokes), consolidation may be considered for up to a year.
Differences between DO in facial region and long bone
Distraction of the jaws differs from distraction of the limbs in at least four ways:
1. The requirements for movement of the bony segments are more complex and requires
complex three-dimensional movements
2. There are complex soft tissue and muscle attachments.
3. Mobilization of the maxilla involves separation at several Sutures as well as osteotomy across
skeletal buttresses, and new bone formation must occur along the thin cortical plates.
4. Facial aesthetic issues
5. Smaller devices often with multidirectional vectors of force
6. Beyond early childhood, the dental occlusion requires precise control of the magnitude and
direction of movement of the jaws.
Advantages
• Less mobilisation
• Reduced operative time
• Reduced hospital stay
• Expands soft tissue (CFM / Cleft palate)
• Avoid bone grafts (Donor site morbidity)
• ? Increased stability
• Reduced blood transfusion
• Avoid prolonged fixation
• Can clinically judge end point of treatment

5. • The ability to lengthen previously grafted bone.
• The ability to repeat distraction osteogenesis at a later date if need be.
• Allows larger movements
Disadvantages
• Second surgery required to remove distractor
• Pain during distraction phase
• Bony movements dependent on distractor position
• Distractor integrity crucial
• Scarring with external devices.
• Significant cooperation is required from both the patient and their family in most cases.
• Technical considerations include the very small size of the jaw, patient management after
surgery during the distraction phase, and avoiding tooth buds and the inferior alveolar nerve
during osteotomy and placement of the appliance. Stereolithographic models facilitate
treatment planning. Current models can identify the presence of tooth buds and the nerve,
as well as provide an opportunity to contour the device prior to surgery.
Complications
 Non compliance and premature removal of distractor
 Pain may be significant and prevent completion of treatment- usually from the TMJ's and
traction elastics can help to "un-load" the joints

6.  Premature consolidation
 Neurological damage
 Failure to form a callus
 Incorrect vectors and therefore incorrect occlusion
 Relapse
 VPI because of large movements
 TMJ ankylosis
 Failure to "grow" normal and need for more surgery
Applications
1. Mandibular distraction can be used to
 A short mandihular ramus that must be lengthened, but with conventional surgery, the
musculature of the pterygomandibular sling does not adapt to lengthening of the ramus.
Distraction histogenesis, at least theoretically, could be a way to overcome this limitation
 Mandibular hypoplasia with airway risk(e.g.Pierre robin neonate/child or nager’s syndromes)
 Mandibular retrognathia severe class ii skeletal pattern more than 10 to 15 m
 Mandibular asymmetry hemifacial microsomia, ankylosed child temporomandibular joint
 Post-mandibulectomy previous ablative surgery
 Sleep apnoea diagnosed by sleep physician due to short ramus and body
2. Mid symphyseal distraction osteogenesis (MSDO)
3. Maxillary distraction
 Bring the midface forward, and holds potential for people with cleft lip and palate and
patients with craniofacial syndromes. However, a Cochrane review by Kloukos in 2016
showed that there is only one small randomised controlled trial concerning the effectiveness
of distraction osteogenesis compared to conventional orthognathic surgery. Based on
measured outcomes, distraction osteogenesis may produce more satisfactory results;
however, further prospective research comprising assessment of a larger sample size with
participants with different facial characteristics is required to confirm possible true
differences between interventions.
 Widening the Maxilla: SARPE as a Form of Distraction
4. augmentation of alveolar ridges

7. 5. Regeneration of mandibular tissue following tumour resection show considerable promise.
Mid symphyseal distraction osteogenesis (MSDO)
 A narrow mandible or a severely constricted mandible which could be associated with any
one of these syndromes (Russell Silver Syndrome, Treacher Collins Syndrome, Craniofacial
Microsomia, Pierre Robin sequence, Apert Syndrome)
 In situations where you have a severe crowding in the lower arch but the upper arch has no
crowding and is normal. The patient has a very obtuse nasolabial angle and you cannot afford
to retract the upper
 Reduced Intercanine width.
 Narrow chin. If it is not desirable to widen the chin, a Genioplasty be performed to maintain
the genial width.
Types of distractors for MSDO
I. Tooth borne
 Simpler with less surgical time
But….
 Disproportional widening at the basal and dentoalveolar level. Del Santo et al. (2000) used
tooth borne devices and found insignificantincreases inbicondylar, bigonial,and biantegonial
widths after mandibular widening. He demonstrated that dentoalveolar expansion was
greater than basal bone expansion with tooth-borne distraction devices.
 Alveolar bone widening not supported by apical base, is usually unstable1
 Periodontal problems, fenestration defects2
 Buccal root resorption
 Anchorage loss

8. II. Bone-borne
 Others state that a greater skeletal effect can be achieved using the bone-borne appliance
owing to the fact that bone-borne distractors transfer the distraction forces directly to the
mandible (Conley and Legan, 2003; Bayram et al., 2007).
 Malkoc ̧ et al. (2006) stated that parallel widening of the mandible could be achieved with
tooth- and bone- borne distraction devices.
 More skeletal changes (Mommaerts et al, 2008)
But….
 Complications (infection, gingival recession, breakage)
 Morbidity seemed to be higher
 Higher cost

9. TMJ symptoms secondary to MSDO
 Every 1 mm of mandibular midline widening = 0.34” of Lateral rotational movement of each
mandibular condyle (Computer simulation data by Samchukov et al)
 However, identifying the cause of postoperative TMJ symptoms in patients treated with
distraction osteogenesisof the mandibular symphysis will be difficult.
 Good occlusion and adaptation to gradual distraction ensures normal joints
 MSDO is kinder to the TMJ due to slower rate of movement compared with traditional
orthognathic procedures with acute skeletal movements
Technique of MSDO
I. Pre-surgical Orthodontics
 Align and level the maxillary arch
 Obtain ideal maxillary arch
 Placement of rectangular surgical maxillary arch
 Fabrication of the intraoral distractor appliance
 Placement of the distractor appliance on the mandibular arch
II. Post-Surgical Orthodontics
 Placement of lower anterior brackets
 Maintenance of the dental gap for 2 months with a plastic tooth
 Orthodontic mechanics are undertaken 2 months after surgery
 Periodically stripping of plastic tooth
 Mobilization of teeth into the distraction site
 Align and level, arch interdigitation and finishing followed by retention

10. TOOTH Movement after MSDO: When should we start?
I. Early tooth movement leads to
 Root resorption (established in canine models)
 Periodontal and bony defects in addition to potential loss of at least 1 tooth
II. Consolidation periods of at least 6-10 weeks before moving tooth into the new bone
 Radiographs for evaluating the bone density in the gap
Mandibular Distraction Devices
These were placed ulilizing intraoral incision to visualize the osteotomy cuts and small stab
incision to place the pins on which the device was mounted.
Advantages
 multiplane distraction can be more easily incorporated into the design,
 the device can be removed easily.
 Activation may be easier than with an internal device as well.
Disadvantages
 excessive scarring
 increased urgency to remove the device because it is so apparent.
 the psychosocial problems associated with an external device may be such that the

11. consolidation period is shortened more than is reasonable.
 an external distractor must be placed at distance from the mandible, which decreases the
rigidity of fixation.
Intraoral device
Types
 Bone borne,
 Hybrid (bone-borne and tooth-borne)
 Tooth-borne
Advantages: Because an intraoral device is much less apparent, it can be left indefinitely
without great pressure from the patient
Disadvantages
 Second surgical procedure is required for removal. In addition, when the ramus is being
lengthened, it may be difficult to activate the appliance entirely within the mouth.
 Additionally, because the natural shape of the mandible is transversely wider in its posterior
aspect and narrower in its anterior aspect, the distractor appliances need to be adjusted by
creating a 5- to 8-mm step in the anterior fixation plates so that the distractor’s screw can be
placed parallel to the axis of distraction. If this is underestimated, the reciprocal forces
exerted on the mandible by the appliance will advance the mandible by moving the proximal
segment not only posteriorly but also laterally and exert very detrimental forces on the TMJ,
which will cause pain, dysfunction, and damage to the joints. In addition, there will be lateral
torque force against the condyle, loosening of the screws, and bending of the appliance as
the muscle forces bend the device. This situation is overcome with the use of heavy class II
elastics, 6 oz per side, during the activation and consolidation period

12. Maxillary Distraction Osteogenesis
 Even though there is still an ongoing debate if rapid maxillary expansion is a version
of maxillary distraction osteogenesis, the first study on true midfacial distraction was
initiated on an ovine model by Rachmiel et al. in 1993 (Rachmiel et al. 1995), in which
they were able to achieve 36 mm of midfacial advancement on the nasofrontal area
with 7 % relapse in 1 year follow-up time.
 This study sets a starting point for the correction of midfacial deformities by
distraction osteogenesis. Currently, the most frequent indications of maxillary
distraction osteogenesis can be counted as cleft lip and palate, and craniofacial
dysostosis associated with maxillary hypoplasia (Imola and Tatum 2002).
 About 25 % of these cleft cases with class III malocclusion require secondary surgical
intervention to correct the maxillomandibular relationship (Ross 1987).
Types of distractors
1. Extraoral
 Distraction osteogenesis ofmaxilla with external tension devices, which takes anchorage from
the temporal region of the head using pin retained hemi halo and screw generated pull by
elastics, provided a solution to the sagittal discrepancies of cleft cases.

13.  This device provided high advancement amounts on
the higher regions of the facial skeleton with low
relapse rate (Figueroa and Polley 1999; Figueroa et al.
2004)
 It provide Greater movements in Multiplanar
 Easy to adjust in DO phase
 Psychosocial implications
 Pin site infection and scars
 Nerve damage
2. Intraoral
 Lin et al 1999, Rachmiel et al 2000
 Avoid cutaneous scars
 Socially more convenient
 Need space for device
 3d control not good
Archwise Distraction on Fixed Orthodontic Appliances

15. DOCKING SITE SURGERY, Once the two segments dock with each other, a second procedure
is required for uniting the two segments. The epithelial tissue between the two segments is
removed, as well as the hypotrophic bone edges from each disk, as described for the
mandible.
Class II Correction by Anterior Alveolar Distraction

19. This method has several advantages upon the conventional methods:
 Shortening the treatment time: Conventional treatment protocol in such cases, in which
either orthognathic surgery or fixed functional orthodontic treatment is an option, takes 16–
24 months time. However, in this approach, alveolar distraction followed by dental implants
shortens the treatment time significantly
 It can be performed under local anesthesia, and it is less invasive.
 Room available for the tongue can increase significantly without any changes to the muscular
structure compared to the mandibular advancement.
 Risk of hemorrhage and developing lip paresthesia is reduced.
 As the tooth movement is less in this method, the root resorption risk and the periodontal

20. problem risk are reduced as well.
Alveolar DISTRACTION OSTEOGENESIS
• Patients medically compromised in whom major bone grafts are not indicated
• As an alternative for reintervention after an unsuccessful bone graft reconstruction
• A need to minimize costs related to the expense of prolonged surgery and hospitalizations
• After removal of benign tumors
• Reconstruction of gunshot wound defects
• Management of osteomyelitis
• Treatment for malunions or nonunions
VELOPHARYNGEAL INCOMPETENCE
The use of pharyngoplasties, pharyngeal flaps, and secondary push-backs to correct
velopharyngeal incompetence has been overcome by distraction osteogenesis of the palatine
bones to project the palate posteriorly. This technique permits titration of the movement
until the velopharyngeal competence is achieved, with predictable results and a low
morbidity, avoiding hyponasality, snoring, and nasal obstruction
Nerve Lengthening

21. Histologically, there are three possibilities after distraction. First, the nerve may exhibit
perineural thickening and decreased surface area of axons, various axonal abnormalities,
myelin thickening, and disruption of the lamellar pattern, and there is a direct relationship
between the number of millimeters advanced and alterations in the nerve. Second, the nerve
can be damaged during surgery and have no axonal connection, with the subsequent
development of fibrosis. Third, a distractor screw can be placed within the nerve canal and
cause damage to or displace neural structures.