Distraction Osteogenesis of the Palate: An Experimental Model · Distraction osteogenesis (DO) has the potential to close the palate with both hard and soft tissues as well as mitigating

Copyright @ 2009 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

Distraction Osteogenesis of the Palate: AnExperimental Model

John M. Menezes, MD, Ross L. Stutman, MD, Patrick S. Murphy, MD,Linda L. Stephenson, BS, MT(ASCP), and William A. Zamboni, MD, FACS

Abstract: Although most cleft palates can be closed with conven-tional mucoperiosteal flap techniques, the occasional wide cleft ordifficult fistula has few options for an early 1-stage reconstruction.Distraction osteogenesis (DO) has the potential to close the palatewith both hard and soft tissues as well as mitigating the possibilityof future oronasal fistula. A right unilateral 5-mm cleft was surgi-cally created in 15 New Zealand white rabbits. In group 1 (N = 5), nofurther repair was performed (NR); in group 2 (N = 5), mucoperios-teal flaps were used to close the cleft for a soft-tissue-only repair(STR); in group 3 (N = 5), a unilateral osteotomy in the palate on thenoncleft side allowed distraction of the palatal shelf across the cleftuntil closed (DO). Clinical examination, MicroYcomputed tomogra-phy bone density, direct cephalometry, and histology were evaluatedat 8 weeks after the completion of distraction. Bone mineral density(BMD; mg/mL) data were obtained from microYcomputed tomogra-phy scans of both the cleft and noncleft sides for each rabbit, and aratiowas obtained [(BMDc/BMDnc)�100]; NR= 1.38, STR = 44.27,DO = 88.36, P = 0.007. Facial measurements revealed no growthdisturbances as a result of DO. Histologic evaluation revealed in-creased organization of new bone in DO group compared with NRand STR. Clinically, DO group rabbits did not show any increasein feeding disturbances, infection, or wound healing. The success ofmembranous facial bone distraction has been applied to a new modelfor palatal repair with the potential to ameliorate the problems asso-ciated with soft-tissue-only repair.

Key Words: Distraction osteogenesis, cleft palate, rabbit,oronasal fistula

(J Craniofac Surg 2009;20: 1583Y1590)

The purpose of surgical closure of both cleft lip and palate is toachieve a normal appearance and normal speech. Bernard von

Langenbeck (1810Y1887) was the first to develop a soft tissue tech-nique of palatal closure that involved a subperiosteal dissectionand the movement of mucoperiosteal flaps.1 Although in most cases,a conventional palatoplasty is adequate, there are a certain smallpercentage of cases in which the cleft defect is wider than repair bysoft tissue flaps, tethered by the greater palatine artery will allow.In addition, fistula, which has been reported to occur at a low butsteady rate in up to 23%, will remain an issue in any repair thatdoes not also address the bony defect. Anterior fistulas, in particular,can be problematic and require measures such as tongue flap forreconstruction and have a relatively high failure rate after attemptedrepair, recurring in up to 37%.2 Anterior fistulas can be particularlyproblematic because the tissue adjacent to the alveolus is limitedand contracted palatal tissues are difficult to advance anteriorly.

In the 20th century, the subperiosteal repair was criticized byVeau as resulting in a short, immobile palate secondary to scarring.3

During the subsequent decades, many authors have reported retar-dation of the growth of midface and maxilla after closure of pala-tal clefts4; this is confirmed in studies comparing operated andnonoperated patients as well.5 Overall, facial growth potential inpatients with cleft lip and palate is generally considered normal. Inother words, the growth restrictions found in patients with cleft lipand palate is a localized phenomenon and not a craniofacial anomalydue to the fact that a normal growth potential has been observed inall craniofacial regions, except where the growth had been directlyinfluenced by surgical intervention.4 Other studies support the no-tion that surgically created scar is causal with regard to the midfacegrowth deficiencies seen in children with cleft palate. Surgicalcorrection in 2 stages instead of 1, which introduced more scar,results in greater growth restriction.6 Therefore, wide clefts that mayrequire delayed or staged repair could potentially benefit by earlyrepair with a horizontal distracter, as would an anterior fistula withan anteroposterior distractor.

Distraction osteogenesis (DO) was developed primarily byGavril Ilizarov in the 1950s and was used to lengthen the longbones of the extremities (enchondral bone). More recently, the tech-nique has been successfully applied to membranous bones of thecraniofacial skeleton by pioneers such as McCarthy et al7 primarilyin the mandible. After these successes, the technique has been ex-panded to other bones of the face including the maxilla at the LeFort I and III levels and even in cranial bone as part of monoblocdistraction.8Y11

To date, distraction has not been a technique applied as aprimary method of human cleft palate repair. The opposite or rapidpalatal expansion using a maxillary osteotomy and a palatal ex-pander to correct a constricted arch has been used, but closure of acleft palate has not.12 Several experimental animal models havedemonstrated the feasibility of posterior palatal lengthening usingDO.13,14 In a few cases of human submucous cleft palate, in which

TECHNICAL STRATEGY

The Journal of Craniofacial Surgery & Volume 20, Number 5, September 2009 1583

From the Division of Plastic Surgery, Department of Surgery, Universityof Nevada School of Medicine, Las Vegas, Nevada.Received April 21, 2009.Accepted for publication May 5, 2009.Address correspondence and reprint requests to Ross L. Stutman, MD,

Division of Plastic Surgery, Department of Surgery, University ofNevada School of Medicine, Las Vegas, 2040 W Charleston Blvd, Ste302, Las Vegas, NV 89102; E-mail: [email protected]

This work was supported in full or in part by a grant from the Universityof Nevada Reno, Junior Faculty Research Grant Fund. This supportdoes not necessarily imply endorsement by the university of researchconclusions. Additional financial support and donation of distractionhardware were provided by KLS Martin (Jacksonville, FL). Noneof the authors has personal financial interest in KLS Martin or anyother product used in this study.

Copyright * 2009 by Mutaz B. Habal, MDISSN: 1049-2275DOI: 10.1097/SCS.0b013e3181b0dbfd


the hard palate is intact and the soft palate is deficient, DO has beenused to lengthen the palate.15 Distraction osteogenesis across apalatal osteotomy is a modality that has been proven in the mem-branous bone of the craniofacial skeleton and that potentially canclose both the bony and soft tissue defects of patients with cleftpalate.

MATERIALS AND METHODSThis protocol was approved by the Institutional Animal

Care and Use Committee of the University of Nevada, Las Vegas,before its initiation. Fifteen male New Zealand white (NZW) rabbits(Western Oregon Rabbit Company, Philomath, OR) weighing be-tween 2.0 and 2.5 kg were used in the study. Upon receipt of allanimals, the staff of the Department of Comparative Medicine,University of Nevada, Las Vegas, examined all animals for anypreexisting abnormalities or defects. Once accepted, the rabbits werehoused individually in cages in humidity- and temperature-controlled rooms. The animals were given standard rabbit foodand water at libitum. At ages 10 to 12 weeks, the animals wererandomly divided into 3 groups of 5 rabbits each: group 1 (norepair = NR), palatal cleft creation without further intervention;group 2 (soft tissue repair = STR), palatal cleft creation withmucoperiosteal flap repair; and group 3 (DO), palatal cleft crea-tion repair with distraction device.

Surgical ProcedureThe animals were anesthetized with an intramuscular (IM)

injection of 35 mg/kg of ketamine and 5 mg/kg of xylazine (AmTech, St Joseph, MO). After sufficient anesthesia, each rabbitreceived 1 dose of benzathine and procaine penicillin G (Bicillin)2,500 IU/kg IM (King Pharmaceuticals Inc, Bristol, TN). Onceasleep, the rabbit’s palate was prepared with betadine (10%povidone iodine) and 70% ethanol for antisepsis and draped witha sterile towel to prevent contamination. After induction of an-esthetic and preparation of the surgical site, a unilateral palatal

cleft was created in a manner similar to that described by Bardachet al.16 A strip of mucoperiosteum was directly excised after in-jection of a local anesthetic (1% lidocaine hydrochloride withepinephrine 1:100,000; Abbot Labs, North Chicago, IL). Sufficientmucosa was maintained to allow repair of mucosa over the borderof the created bony cleft so as not to leave exposed bone. A 5-mmcleft was then created in the palatal bone with a surgical burrfollowed by repair of the nasal to the oral mucosa at the cleft mar-gin with a 5-0 Vicryl suture (Ethicon Inc, Somerville, NJ) (Fig. 1).

For the group receiving soft tissue repair (group 2), lateralpalatal incisions were made 0.5 mm lingual to the alveolus andmucoperiosteal flaps developed preserving the neurovascularpedicles to the flaps. The flaps were then repaired in the midlinewith additional sutures placed at the nasal mucosa to eliminatepotential dead space (Fig. 2). Group 3 did not have a soft tissuerepair. Here a lateral osteotomy was made on the noncleft sidewith perforations created with a drill bit and completed with anosteotome. The distraction mechanism, a modification of the Mi-cro Zurich infant mandibular distraction device (KLS Martin,Jacksonville, FL) was placed across the cleft with titanium screwssecuring the device bilaterally (Figs. 3 and 4).

Postoperatively, all rabbits were observed until fully awake.One dose of buprenorphine 0.01 mg/kg IM (Reckitt BenckiserPharmaceuticals, Inc, Richmond, VA) was given intraoperativelyand then every 12 hours for 2 days for analgesia. All animals wereobserved for signs of pain and distress (such as agitation, inabilityto ambulate, decreased food and water intake) on a daily basis for3 days and then for 3 days every week. Food and water consumptionwas monitored throughout the study. All animals were weighedpreoperatively, at 1-week intervals throughout the study, and at thetime of euthanizing.

No additional manipulation was performed after the initialoperation for groups 1 and 2. For group 3, after a 5-day latencyperiod, distraction was started with 0.3-mm turns to the device twicea day for a total of 10 days to close the 5-mm defect. After the

FIGURE 1. Group 1, no repair group. Preoperative photograph of rabbit palate (A) and 5-mm unilateral cleft created (B).

FIGURE 2. Group 2, soft tissue repair. A, Mucoperiosteal flap elevation. B, Midline soft tissue repair of created cleft palate.

Menezes et al The Journal of Craniofacial Surgery & Volume 20, Number 5, September 2009

1584 * 2009 Mutaz B. Habal, MD


completion of distraction, a bone consolidation period of 8 weekswas allowed to occur before administration of euthanasia and ex-amination of the tissues. At week 9, all rabbits were euthanized bylethal doses of intravenous pentobarbital.

Tissue HarvestingAll rabbits were immediately decapitated, and all soft tissue

to the level of periosteum was removed, with the exception of thepalatal mucosa. The distraction device was removed from all animalsin which it was placed. Lastly, the mandible was disarticulated anddiscarded. All skulls were then placed in formalin for preservation.

Skull MeasurementsDirect cephalometry was performed on each of the rabbit

skulls to evaluate any changes in facial growth between the 3 treat-ment groups. The following landmarks were identified and markedon the skull surface.MVmedial margin of the alveolus of the right first molarNVmedial margin of the alveolus of the left first molarOVmedial margin of the alveolus of the right last molarPVmedial margin of the alveolus of the left last molarMYN (anterior maxillary width)Vlength between the medial

margins of the alveoli of the first molarsOYP (posterior maxillary width)Vlength between the medial

margins of the alveoli of the last molarsYYY¶ (posterior facial width)Vlength between frontal bone lateral

margins in front of posterior supraorbital processZYZ¶ (posterior facial width)Vlength between posterior point of

zygomatic-squamosal suture(Fig. 5)

MicroYComputed TomographyEach rabbit skull was sent to San Antonio Children’s Cancer

Research Institute for micro-computed tomography (CT) evaluation.Micro-CT measurements of bone mineral density (BMD) and bonemineral content (BMC) were performed of the region of interest usingGEMicroview software (General Electric Healthcare,Waukesha,WI).

FIGURE 3. Distraction device (KLS Martin).

FIGURE 4. Group 3, DO. Intraoperative view of distractiondevice in place before initiation of distraction.

FIGURE 5. Direct cephalometry technique. A, Ventral view oflandmarks identified and measured. MYN was used tomeasure anterior maxillary width; OYP, posterior maxillarywidth. B, Dorsal view of landmarks YYY¶ and ZYZ¶ posteriorfacial width.

FIGURE 6. Changes in body weight of each treatmentgroup from beginning (date of cleft creation T soft tissuerepair or placement of distraction device) to final (9 weeksafter initial cleft creation). Note: error bars represent SEM.

The Journal of Craniofacial Surgery & Volume 20, Number 5, September 2009 Distraction Osteogenesis of the Palate

* 2009 Mutaz B. Habal, MD 1585


Each palate was also measured at the opposite noncleft portion ofhard palate. This was performed to allow each skull to serve as itsown control, as well as give absolute quantitative results.

HistologyAll skulls were sent in formalin to Quest Diagnostics (Las

Vegas, NV). Each palate was sectioned per Quest Diagnostics andstained with hematoxylin and eosin (H&E). All histologic evaluationwas performed by a single pathologist blinded to the treatment groupof each skull.

Statistical AnalysisGroup differences across the measured parameters were

statistically analyzed using analysis of variance. All calculationswere performed using Stat Pak 4.1 (Portland, OR). A P G 0.05 wasconsidered significant.

RESULTS

Body WeightThere were no significant differences in body weight be-

tween the 3 treatment groups at the time of operation: group 1 (NR),

mean weight of 2.53 kg (SEM, 0.18); group 2 (STR), mean weightof 2.54 kg (SEM, 0.03); and group 3 (DO), mean weight of 2.48 kg(SEM, 0.06). All animals consistently gained weight throughouteach week of the 9-week study. At 9 weeks, there was no significantdifference in overall weight gained between groups (Fig. 6).

Clinical ImpressionsThere were no complications of infection, wound healing,

or mechanical failure of the distraction device. All animals wereable to eat and drink without obvious difficult. Clinical obser-vation at 9 weeks of palatal closure revealed a more organizedsoft tissue arrangement overlying the cleft portion of the palatein the DO group compared with the STR and NR groups. Allgroups seemed to have at least some bone formation at the cleftsite (Figs. 7Y9).

Skull MeasurementsDirect cephalometry was performed to evaluate any changes

in skull growth throughout the treatment groups. Anterior maxil-lary width was measured by anterior maxillary width. There wasno significant difference between groups because the mean lengthsin millimeters for the NR, STR, and DO groups were 11.9 (SEM,0.17), 11.4 (SEM, 0.4), and 11.3 (SEM, 0.44), respectively. Poste-rior maxillary width was measured by posterior maxillary width.

FIGURE 7. No repair group, representative photograph at9 weeks after creation of cleft palate.

FIGURE 8. Soft tissue repair group, representativephotograph at 9 weeks after creation of cleft palate andimmediate soft tissue repair with mucoperiosteal flaps.

FIGURE 9. Distraction osteogenesis group, representativephotograph at 9 weeks after creation of cleft palate andplacement of distraction device, then 8 weeks after fulldistraction.

FIGURE 10. Direct cephalometry. Note: error barsrepresent SEM.




There was also no significant difference between treatment groups.The mean posterior maxillary width for the NR was 13.0 (SEM,0.63), STR was 13.80 (SEM, 0.73), and DO was 13.80 (SEM, 0.41).

Posterior facial width was evaluated using YYY¶ and ZYZ¶There was no significant difference in these measurements betweentreatment groups. YYY¶ for the NR, STR, and DO in millimeterswere 14.4 (SEM, 2.16), 14.0 (SEM, 1.79), and 17.1 (SEM, 2.42).The ZYZ¶ measurements were 45.5 mm (SEM, 1.45) for the NRgroup, 44.6 mm (SEM, 1.03) for the STR group, and 42.7 mm(SEM, 1.43) for the DO group.

Overall, there were no significant differences between thetreatment groups with regard to facial growth (Fig. 10).

Micro-CTMicro-CTwas used to evaluate both BMC in milligrams and

BMD in milligrams per milliliter. Each animal also served as itsown control by evaluating the noncleft side of the palate (BMCncand BMDnc) to the cleft side (BMCc and BMDc).

Bone mineral content of the cleft side was significantly re-duced in the NR group compared with both the STR and DO groups(P = 0.0064 and 0.0057, respectively). Interestingly, although therewas a slight increase in BMC of the DO compared with the STR,this did not meet statistical significance. There was also no sig-nificant differences in BMCnc between the NR and STR groups;however, there was a significant difference between the STR andDO groups (P = 0.0093). This likely was due to the decreased den-sity of the osteotomy site in the DO group (Fig. 11).

Bone mineral density of the cleft side was also significantlyreduced in the NR group compared with both the STR and DOgroups (P = 0.0078 and 0.0087, respectively). However, there wasno significant difference in BMDc between STR and DO. As withBMCnc, BMDnc revealed similar findings, with no significant dif-ferences between the NR and STR groups or NR and DO groups.However, a significant difference between the STR and DO groups(P = 0.0042) did exist, again likely due to the incomplete ossifica-tion of the osteotomy site (Fig. 12).

Each group was also compared as a ratio of BMCc/BMCncand BMDc/BMDnc to better evaluate these measures using eachgroup as its own control. The BMCc/BMCnc ratios for the NR,STR, and DO groups were 3.01%, 44%, and 89.9%, respectively.This did prove statistically significant for all groups; NR com-pared with STR, P = 0.0099; NR compared with DO, P G 0.0001;and STR compared with DO, P = 0.0035 (Fig. 13). The BMDc/BMDnc ratios for the NR, STR, and DO groups were 1.38%,44.27%, and 88.36%, respectively. This also did reveal statisticalsignificance with respect to all groups: NR/STR, P = 0.0118; NR/DO, P G 0.0001; and STR/DO, P = 0.0072 (Fig. 14).

HistologyAfter H&E staining and viewing at 100�, the results from

each respective group were uniform in appearance. The NR groupshowed minimal bone remodeling and some osteoblastic activity(Fig. 15). The STR group was noted to have some collagen present

FIGURE 11. Micro-CT BMC of cleft (c) and noncleft (nc) sidesof palate. Note: error bars represent SEM.

FIGURE 12. Micro-CT BMD of cleft (c) and noncleft (nc) sidesof palate. Note: error bars represent SEM.

FIGURE 13. Micro-CT evaluation of BMCc/BMCnc.Note: error bars represent SEM.

FIGURE 14. Micro-CT evaluation of BMDc/BMDnc.Note: error bars represent SEM.




with increased number of layered osteoblasts parallel to existingbone compared with the NR group (Fig. 16). Lastly, the DO groupdemonstrated exuberant bone remodeling with increased osteoblastsand organized collagen matrix in longitudinal lines connecting areasof new bone (Fig. 17).

DISCUSSIONDesigning cleft palate models can be performed either by

surgically creating a cleft, as was done in this protocol, or congeni-tally creating a cleft palate. An animal model in which a congenitalcleft palate is created by teratogens given to pregnant mothers wouldbe ideal. There have been several reports of such congenitally createdcleft palates.17Y19 However, there is no way to standardize the sizeand extent of the cleft palate. An additional disadvantage to the con-genitally created cleft palate model is the high risk of additionalanomalies that could further affect the health of the animals andtherefore standardization of the study.

Surgically created clefts have been studied in several animalmodels including mice, rabbits, cats, dogs, and sheep. The use of a

rabbit model for several phases of study has been performed, in-vestigating the embryology, growth, and effects of palatal, lip, andalveolar surgery. Several of these studies provide detailed cephalo-metric analysis of cranial growth as a basis for comparison.16,20Y25 Inaddition, several stages of palatogenesis in the NZW rabbit arecomparable to human palatal development.26 We believe that thismakes the NZW rabbit model appropriate to investigate the effec-tiveness of DO on cleft palatal repair.

We propose that DO may have utility in decreasing the rateof oronasal fistula as well as speech disturbances in wide clefts bycreating a more normal bony anatomy at the cleft site. It also has theadvantage of reducing soft tissue scarring seen with laterally basedmucoperiosteal flap closure, although the effect of a palatal osteo-tomy on midface growth has yet to be further investigated. Weevaluated bone density using micro-CT to obtain both a quantita-tive BMD and content. Micro-CT has been used in previous stud-ies to quantify both bone density and mechanical properties inanimal models including rabbit.27 The use of this technology hasalso been validated against other common means of measuring bonedensity including dual energy x-ray absorptiometry and peripheralquantitative computer tomography.28 Our results show that thereis a significant difference in the density of bone created with DO ascompared with either a control NR or STR model. The percentageof cleft to noncleft ratio was also performed to obtain standardiza-tion within each micro-CT. Although there was a significant dif-ference in the cleft/noncleft ratio between the DO and the controlgroups, this may be somewhat misleading. The additional osteo-tomy created in the noncleft side of the DO group likely affected thebone density ratio. This was further revealed in assessing the de-creased BMC and BMD of the noncleft side of the DO group pal-ates compared with the other 2 groups. Therefore, it is prudent toassume that at 9 weeks, this osteotomy site is not be fully ossified,and the ratio of cleft to noncleft density may be skewed.

The process of progressive gap healing to lengthen bonealso has the beneficial effect of simultaneous expansion of the softtissues, including vessels, nerves, muscle, and epithelium. This hasbeen termed distraction histiogenesis.29 Many of these techniqueshave been developed as an extension of conventional techniquesin children with craniofacial disorders such as cleft lip and palate.We believe that the mechanisms of distraction histiogenesis couldprevent the facial growth disturbances often seen in humans inwhich a standard soft-tissue-only repair has been associated. To

FIGURE 15. No repair group, H&E stain at 100�. Thickarrow shows osteocytes in lacunar spaces. Thin arrow showsosteoblasts lining trabeculae.

FIGURE 16. Soft tissue repair, group H&E stain at 100�. Thickarrow shows osteocytes in lacunar spaces. Thin arrow showsosteoblasts lining trabeculae. Arrowhead shows collagenmatrix being deposited by osteoblasts lined up parallel toexisting bone.

FIGURE 17. Distraction osteogenesis group, H&E stain at100�. Thick arrow shows osteocytes in lacunar spaces.Arrowhead shows collagen matrix being deposited byosteoblasts lined up parallel to existing bone.




evaluate this, we performed direct cephalometric measurementsto evaluate the anterior and posterior maxillary width as well asposterior facial width. Although there are several cephalometricindices, we chose the ones that would most closely correlate tothe midface growth deficiencies seen in clinical practice.30,31 Thisstudy did reveal that there are no significant differences with regardto facial growth between treatment groups. However, there areseveral limitations in this study that make it difficult to assumeconclusively that DO will prevent facial disturbances. First, allcephalometric measurements were performed in a direct fashion onpostmortem skulls; therefore, we do not have any precleft creationdata to compare these data. Also, we chose to use 10- to 12-week-oldrabbits because it was at this age that they reached a suitable sizeand weight to safely perform the surgical intervention and post-operative care. In future studies, we will need to use younger rabbitsbefore much of their skull and midface growth occurs to obtain amore conclusive answer about the effect of an osteotomy and dis-traction on growth as compared with mucoperiosteal flaps.

The formation of an oronasal fistula is a complication ofpalate repairVone that is particularly difficult to correct. The inci-dence of this complication ranges between 3% and 45%.32 Surgicaltechnique has been found to be one factor influencing the frequencyof palatal fistula with Wardill, Furlow, Langenbeck, and Dorrancestyles of closure having progressively fewer fistulas.2 However,possibly more important than type of surgical repair, the preop-erative Veau classification may predict which patients are at in-creased risk of complications such as oronasal fistula.33 In addition,although several options exist for their closure, none of them areideal with an overall recurrence rate near 40% depending on the sizeand location of the fistula.2 Persistent fistulas can affect speechadversely and are an avenue for food and fluids to enter the nose;they can also complicate the management of the alveolar cleftwhen it is time for bone grafting. Most fistulas occur anteriorly, orin the postalveolar position. This is a particularly difficult areato correct due to the lack of mobile soft tissue with a healthy bloodsupply. In some case reports, DO has facilitated the closure offistulas. Both in the case of an anteriorly located fistula associatedwith the osteotomy and movement of a palatal tooth34 and as in acase of a fistula associated with an irradiated palate.35 DO has beenshown to be a potential modality for repair of cleft fistula.36 If usedat the time of primary repair, the new bone generated by DO acrossthe cleft could eliminate the complication of palatal fistula as wellas be a mode of therapy for current patients with cleft fistulas.

In conclusion, we believe that this study demonstrated thatDO can be safely performed to close a surgically created cleft pal-ate in a rabbit model. This technique has the potential to be suc-cessful in treating some of the wider and more severe cleftingpatterns, which more likely lead to complications. Distraction os-teogenesis may also be used as an option to treat complications ofpalatal surgery, including oronasal fistulas, and reduce tertiary op-erations. Future studies on younger rabbits will be needed to as-sess whether DO has a true advantage over soft tissue repair inpreventing facial growth disturbances.

ACKNOWLEDGMENTSWe thank Drs Sharon Murphy and Charles Keller of the San

Antonio Children’s Cancer Research Institute for donating themicro-CT scans. We also thank Dr Carol A. Van der Harten andQuest Diagnostics, Las Vegas, NV, for their preparation andassessment of the histologic analysis.

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Distraction Osteogenesis of the Palate: An Experimental Model · Distraction osteogenesis (DO) has the potential to close the palate with both hard and soft tissues as well as mitigating