CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY

Is It Safe and Effective to Lengthen a Chin With Interpositional Allogenic (Iliac) Graft? Jeffrey C. Posnick, DMD, MD,* and Ali Sami, DDSy Purpose:

This is a retrospective review of a consecutive series of patients undergoing chin lengthening at the time of orthognathic surgery over a 3-year timeframe.

Materials and Methods:

The genioplasty procedures studied included lengthening to the extent that an interpositional graft was deemed necessary (n = 19). Allogenic (iliac) corticocancellous bone was used in all cases. Each patient underwent lateral cephalometric radiography within 2 months before and 5 weeks after surgery. From the radiographs, quantitative measurements (millimeters) were made to document the vertical lengthening and horizontal advancement achieved. Chin region wound healing parameters were reviewed to document evidence of infection, sequestra, need for reoperation, and evidence of fibrous union. Inpatient hospital and outpatient office records were reviewed for any evidence of sepsis or viral transmission.

Results:

The patients’ mean age at operation was 35 years (range, 15 to 58 yr). Analysis of preoperative and 5-week postoperative radiographs documented a mean vertical lengthening of 7 mm (range, 4 to 10 mm). The mean horizontal advancement at the pogonion was confirmed to be 2 mm (range, 1 to 3 mm). None of the study patients sustained chin region infection graft sequestra, fibrous union, or need for reoperation. There were no cases of postoperative sepsis or viral illness to indicate systemic infectious sequelae.

Conclusion:

The study confirms the safety of allogenic (iliac) corticocancellous grafting to fill interpositional defects associated with a transverse symphyseal lengthening osteotomy. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-9, 2015

Obwegeser1 introduced the intraoral approach to completing an osseous genioplasty in 1957. More than half a century later, this relatively straightforward technique remains underused when surgeons are asked to make cosmetic changes to the chins of their patients. Contemporary maxillofacial surgeons recognize that a considerable percentage of individuals with horizontal (sagittal) chin deficiency also have an altered lower anterior facial height. Individuals with decreased lower anterior facial height in combination with a retrusive-appearing chin (ie, primary mandibular deficiency or maxillomandibular deficiency) tend to have an exaggerated and excessively deep

labiomental fold with acute angulation between the lower lip and the soft tissue chin pad.2,3 A pleasing labiomental fold is an essential component of optimal lower face esthetics.4 When a lateral cephalometric radiograph is taken with a patient in the natural head position, with lips relaxed and lower jaw at rest, an accurate image of the facial skeleton and the overlying soft tissues from which to judge profile esthetics can be documented. When completing an osseous genioplasty to vertically lengthen and horizontally advance the chin to mask a mandibular deficiency or as part of a comprehensive orthognathic correction, an interpositional gap (dead space) is created in the process. Unless the dead

*Director, Posnick Center for Facial Plastic Surgery, Chevy Chase,

Address correspondence and reprint requests to Dr Posnick:

MD; Clinical Professor, Departments of Surgery and Pediatrics,

5530 Wisconsin Avenue, Suite 1250, Chevy Chase, MD 20815;

Georgetown University, Washington, DC; Clinical Professor,

e-mail: [email protected]

Department of Orthodontics, University of Maryland, School of

Received November 25 2014

Dentistry, Baltimore, MD; Adjunct Professor, Department of Oral and Maxillofacial Surgery, Howard University College of Dentistry,

Ó 2015 American Association of Oral and Maxillofacial Surgeons

Washington, DC.

0278-2391/15/00112-3

Accepted February 4 2015

yChief Resident, Department of Oral and Maxillofacial Surgery,

http://dx.doi.org/10.1016/j.joms.2015.02.002

Howard University Hospital, Washington, DC. Dr Posnick receives royalties for specific products from the Stryker Corporation.

1

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CHIN LENGTHENING WITH ALLOGENIC BONE GRAFT

space is filled with an appropriate graft material, infection and malunion are presumed to be at higher risk of occurrence. Interpositional graft materials frequently considered to fill these gaps include autogenous bone,5,6 block hydroxyapatite,7 and allogenic bone.8,9 Each of these graft choices has advantages and inherent risks.10 Interestingly, the use of allogenic (iliac) bone as an interpositional graft in association with a lengthening genioplasty has not been adequately reported. The purpose of this retrospective clinical study was to evaluate the use of allogenic (iliac) corticocancellous bone to fill the dead space after a transverse symphyseal osteotomy to lengthen the chin. The authors hypothesized that an allogenic (iliac) graft could be safely and effectively used to fill interpositional defects associated with chin lengthening osteotomies. The specific aims of the study were to 1) describe the surgical technique of osseous genioplasty and allogenic bone graft placement as carried out in the study group; 2) document the size of interpositional chin defects requiring grafting for a spectrum of dentofacial deformities; 3) assess the occurrence of infection resulting from osseous genioplasty and interpositional allogenic grafting in the study group; and 4) assess the occurrence of graft rejection or systemic illness when allogenic bone was used in the study group.

Demographic Variables The demographic variables included age and gender.

Materials and Methods STUDY DESIGN AND SAMPLE

To assess the research objectives, the authors designed a retrospective cohort study. The study sample was derived from patients treated by 1 surgeon (J.C.P.) in private practice (Posnick Center for Facial Plastic Surgery, Chevy Chase, MD) with surgery being carried out at a single hospital (MedStar Georgetown University Hospital, Washington, DC) from 2009 through 2012. To be included in the study sample, each patient required correction of a dentofacial deformity that at a minimum included Le Fort I osteotomy, bilateral sagittal split osteotomies of the mandible, and osseous genioplasty. Correction of the chin deformity had to require lengthening to the extent that an interpositional graft was considered necessary. The interpositional graft used in each patient was allogenic (iliac) corticocancellous bone. Patients were excluded if their jaw deformity diagnosis was syndromal, related to cleft, redo orthognathic surgery, post-traumatic, or related to tumor. The appropriate institutional review board approved this study and protocol. STUDY VARIABLES

The study variables were grouped into 6 categories: demographic, medical, anatomic, operative, bone graft source, and outcome.

Medical Variables A medical history for allergies was recorded. For patients not allergic to penicillin, intravenous prophylactic antibiotics of cefazolin 1 g was given just before surgical incision and then repeated every 8 hours for 4 additional doses. This was followed by an additional 4-day course of cephalexin (500 mg every 6 hours as an oral suspension). Patients allergic to cephalosporins were given clindamycin as an alternative antibiotic. Anatomic Variables The 2 anatomic variables were morphology of the jaws and morphology of the chin. The first anatomic variable was the pattern of presenting developmental dentofacial deformity. At presentation, each patient was sub-grouped into 1 of 6 jaw growth patterns, including primary mandibular deficiency, maxillary deficiency with relative mandibular excess, asymmetric mandibular excess, long face, short face, and bimaxillary dental protrusion. The second anatomic variable was the presenting chin region dysmorphology. All study patients presented with notable vertical deficiency combined with limited horizontal deficiency of the chin. Operative Variables Operative variables included symphyseal osteotomy design, method of osteotomy fixation, and method of grafting. With the lower lip everted, an incision is made in the depth of the vestibule from canine to canine, stopping just short of the visualized mental nerve on each side. The central two thirds of the incision are extended down to bone. A full cuff of mucosa and muscle is maintained adjacent to the attached gingiva of the anterior teeth, allowing for adequate layered wound closure of the muscle and mucosa. Subperiosteal dissection with an elevator exposes the anterior surface of the chin, although not completely to the inferior border of the central chin. The dissection remains inferior to the mental nerve, with lateral exposure to the inferior border of the mandible. A sterile pencil is used to mark the location of the oblique osteotomy. The osteotomy is completed with oscillating and reciprocating saws. With completion of the osteotomy, the distal chin is held in position to achieve the degree of vertical lengthening and horizontal advancement desired. The chin is lengthened anteriorly, resulting in an interpositional dead space while pivoting on the posterior aspect (of the chin osteotomy) to maintain contact to the mandible. The surgeon contours a 4- to 6-hole titanium straight plate to span the osteotomy site (on each side) and then secures each with screws (1.7 mm in diameter and 4 mm in length). The superior screw for each plate is usually

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placed between and inferior to the lateral incisor and canine on each side (Fig 1). A block of allogenic corticocancellous graft is crafted and tightly inset in the gap between the 2 plates. The authors do not find it necessary or advantageous to place the graft lateral to the plates, although a small dead space exists. With the graft wedged in place, an additional straight plate is contoured and placed vertically in the midline across the osteotomy site and directly over the graft and then secured with screws (1.7 mm in diameter and 4 mm in length; Fig 1). Bone Graft Variable The allogenic (iliac) corticocancellous graft used was processed, packaged, and sold by Life Net Health (Virginia Beach, VA). They describe the allograft bioimplant as being processed from donated human tissues, resulting from the gift of an individual or the donor’s family. The bioimplant is cleaned and disinfected through a proprietary process. The allografts are preserved through a freeze-dried process. The manufacturer claims that all donors have been screened and that tissues have been recovered, processed, stored, tested, and distributed in accordance with current US Federal regulations as promulgated in CFR 1270 and 1271 current standards for tissue banking set forth by the American Association of Tissue Banks (McLean, VA) and international laws and regulations as required. The allograft bioimplant was deemed suitable for implantation by Life Net Health. A physician medical director evaluated and followed donor variables to determine donor suitability: infectious disease test results, current donor medical history, behavioral risk assessment interview, physical assessment, relevant medical records, including medical history, laboratory test results, and autopsy or coroner reports (if performed). All donors are tested for relevant infectious diseases. Testing is performed by laboratories that are registered with the US Food and Drug Administration and certified under the Clinical Laboratory Improvement Amendments of 1988 and 42 CFR 493. Test methods that are licensed, approved, or cleared for donor screening by the Food and Drug Administration are used as available. Outcome Variables The outcome variables included size of defect grafted, occurrence of chin region infection, occurrence of graft rejection, occurrence of systemic illness related to allograft, and chin outcome. Each patient underwent lateral cephalometric radiography within 2 months before and 5 weeks after surgery. From the radiographs, quantitative measurements (millimeters) were made to document the extent of vertical lengthening and horizontal advancement achieved. This served as an indicator of the osteotomy site gap to be grafted.

Chin region infection was coded to have occurred if there were specific physical findings and additional treatment was required at any time during the first year after surgery. Swelling and tenderness with drainage through the oral wound in the chin region was coded as an infection. Then, treatment with appropriate antibiotics and surgical drainage would be required. Graft rejection was coded to have occurred if sequestra of bone or surgical debridement of bone was required at any time during the first year after surgery. Systemic illness related to the allograft was considered if records indicated sustained fever, a prolonged hospital course, or diagnosis of a viral illness consistent with human immunodeficiency virus, hepatitis C, or cytomegalic virus within 1 year after surgery. An acceptable outcome was coded to have occurred if a revision procedure in the chin region (skeletal or soft tissue) was not requested or required within the first year after surgery. COLLECTION, MANAGEMENT, AND ANALYSIS OF DATA

The data were abstracted and recorded on a standardized data collection form by 1 author (A.S.) from the hospital and outpatient records. This included data from each patient’s pre- and postoperative lateral cephalometric radiographs. Quantitative measurements (millimeters) were made to document the extent of vertical lengthening and horizontal advancement achieved in the chin region. The cephalograms were calibrated to yield a 1:1 ratio of radiographic image to actual size. The vertical change was measured as the height gained (millimeters) across the osteotomy gap. The horizontal advancement was measured by first drawing a line through the B point that was perpendicular to the mandibular occlusal plane. The distance from this line to the pogonion, also measured in a perpendicular plane, was designated as the horizontal advancement (millimeters) achieved. The data were entered and a database was created using Excel (Microsoft, Redmond, WA). The data were exported to SPSS 10.0 (SPSS, Inc, Chicago, IL) for statistical analysis. Descriptive statistics were computed for all variables. Bivariate analysis was computed to measure any associations between each predictive variable and outcome. Biologically relevant measurements (age and gender) and relevant bivariate associations for which the probability was less than .05 were included in a multiple logistic regression model.

Results DEMOGRAPHICS

The patients’ mean age at operation was 35 years (range, 15 to 58 years). The group consisted of 11

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CHIN LENGTHENING WITH ALLOGENIC BONE GRAFT

FIGURE 1. When considerable vertical lengthening of the chin is planned, an interpositional graft is crafted and placed in the gap. The graft fills the central gap between the standard titanium fixation plates in place. The authors do not find it necessary or advantageous to place graft in the lateral aspect of the gaps. An additional plate and screws are generally placed vertically in the midline across the osteotomy site and directly over the graft. A, Illustration depicts osseous genioplasty with vertical lengthening and standard titanium plate and screw fixation. B, Crafted allogenic (iliac) corticocancellous graft is inset and further secured with a titanium plate and screws. (Posnick JC: Aesthetic consideration of the chin: Evaluation and surgery, in Posnick C [ed]: Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2013, pp 1564-1612, Figure 37-20G). Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

POSNICK AND SAMI

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FIGURE 2. A 26-year-old woman with a short face growth pattern and interest in improving her profile and smile. The patient’s history confirmed heavy snoring, restless sleeping, and daytime fatigue. Examination documented a deviated septum and hypertrophic inferior turbinates. An attended polysomnogram confirmed mild obstructive sleep apnea. The patient’s surgery included maxillary Le Fort I osteotomy in segments (horizontal advancement, vertical lengthening, arch form correction, and clockwise rotation) with an interpositional allogenic bone graft, bilateral sagittal split ramus osteotomies (horizontal advancement), and osseous genioplasty (vertical lengthening of 10 mm and horizontal advancement of 3 mm) with an interpositional allogenic bone graft. As a result of treatment, the patient has an open airway, improved occlusion, and favorable facial esthetics. A, Frontal view with smile before treatment. B, Frontal view with smile after treatment. C, Profile view before treatment. D, Profile view after treatment. (Fig 2 continued on next page.) Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

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CHIN LENGTHENING WITH ALLOGENIC BONE GRAFT

FIGURE 2 (cont’d). E, Lateral cephalometric radiograph before treatment. F, Lateral cephalometric radiograph after treatment. (Posnick JC: Short face growth patterns: Maxillo-mandibular deficiency, in Posnick JC [ed]: Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2013, pp 866-896, Figure 23-7). Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

female and 8 male patients. No patients were lost to follow-up or excluded because of inadequate records. The study group was limited to patients with a developmental dentofacial deformity characterized as a short face growth pattern (n = 10), maxillary deficiency with relative mandibular excess growth pattern (n = 5), primary mandibular deficiency growth pattern

(n = 3), and asymmetric mandibular excess growth pattern (n = 1; Fig 2). Eleven of 19 patients (58%) also were documented to have obstructive sleep apnea. All patients underwent simultaneous sagittal split ramus osteotomies of the mandible, Le Fort I maxillary osteotomy, and osseous genioplasty with an allogenic (Iliac) interpositional bone graft as part

POSNICK AND SAMI

of their orthognathic correction. Two patients allergic to cephalosporin were given clindamycin (Table 1). RADIOGRAPHIC MEASUREMENTS OF CHIN REPOSITIONING

Comparison of the preoperative with the 5-week postoperative lateral cephalometric radiographs for each patient showed a mean vertical lengthening of 7 mm (range, 4 to 10 mm; Fig 3). The mean horizontal advancement of the chin at the pogonion was confirmed to be 2 mm (range, 1 to 3 mm; Fig 4). WOUND HEALING AT OSTEOTOMY SITE

None of the study patients sustained an infection in the chin region. There was no incidence of graft sequestra, fibrous union, or need for reoperation in the chin region in any of the study patients during the first year after surgery. SYSTEMIC EFFECTS OF ALLOGENIC BONE GRAFT

There were no cases of persistent postoperative fever, chills, or suggestion of sepsis. The average hospital stay was 2 nights (range, 1 to 3 nights). Although serum analysis for postoperative viruses (ie, human immunodeficiency virus, hepatitis C, or cytomegalic virus) was not specifically performed, there were no symptoms or signs suggestive of a chronic viral or bacterial infection in any patient for a minimum of 1 year after surgery. CHIN REGION—PATIENT SATISFACTION

There was no need or request for redo chin osteotomy or soft tissue revision procedures of the region of the lip and chin to improve morphology or for any other reason during the study period.

Discussion The esthetic advantage of chin lengthening is most frequently seen in individuals with a short face growth pattern (ie, maxillomandibular deficiency).2,7 This common pattern of dentofacial disharmony is associated with a degree of vertical and horizontal (sagittal) deficiency in the maxilla and mandible. Measuring the ratio of the lower facial height (ie, the subnasion to the menton) to the upper facial height (ie, the glabella to the subnasion) will confirm that the lower height is diminished. The height of the alveolar process of the 2 jaws is decreased. As a result, the labiomental sulcus is typically deep and the lower lip is everted. In most cases, osseous genioplasty with vertical lengthening and limited horizontal advancement will correct the anterior mandibular alveolar height and improve the overlying soft tissue contour.2,3

7 In 1964, Converse and Wood-Smith11 produced textbook illustrations of how a corticocancellous bone block could be inserted into a symphyseal osteotomy site to vertically lengthen a chin. No specific patients were described. In 1980, McBride and Bell12 also discussed the concept of chin lengthening with interpositional grafting. Wessberg et al13 are credited with the first actual report of a patient who underwent vertical lengthening of the chin by osteotomy and autogenous bone grafting. Freihofer8 reported on the use of interpositional banked bone for this purpose in 1 patient. In 1994, Luhr14 reported on the advantage of plate and screw fixation and the use of interpositional hydroxyapatite granules when lengthening the chin in conjunction with an osseous genioplasty. In 1984, Wolfe15 presented 2 cases using interpositional autogenous bone to vertically lengthen a chin. Rosen7 reported on a series of 8 patients who underwent vertical augmentation genioplasty using a symphyseal osteotomy and interpositional implantation of porous block hydroxyapatite stabilized with plate and screw fixation. Lye et al9 reported on the use of demineralized bone matrix for interpositional grafting during chin lengthening, also with good success. Although block hydroxyapatite has proved successful as an interpositional gap filler and demineralized bone matrix provides a similar function with an osteoconductive scaffold, a bone allograft has osteointegrative capabilities at the interphase between host and recipient and offers the advantage of being fully replaced through the process of creeping substitution over time.16,17 The unique clinical circumstances and specific patient preferences must be factored in when making the decision of which interpositional graft material to use in conjunction with chin lengthening. Bone allografting is currently a common choice for the orthopedic and spine surgeon when interpositional grafting is required.16,18 It has the advantage of not requiring donor-site harvesting and has few limitations of graft availability. The architectural foundation of the allograft creates a natural osteoconductive scaffold for fibrovascular ingrowth, cellular attraction from the host interface, and eventual bony development. Allografting also exhibits good osteointegrative capability at the interface between host and recipient. By nature of allograft processing, osteogenic cells (osteoblasts and precursors) are largely unavailable. Although osteoinductive properties fluctuate depending on the preparation of the allograft, these grafts provide variable structural support. Allografts are available as cortical, cancellous, or corticocancellous grafts.18 The cancellous graft is traditionally incorporated by endochondral ossification through the allograft scaffolds with minimum initial strength that increases over time. In contrast, incorporation of the cortical graft is by creeping substitution by way of intramembranous ossification,

Table 1. PATIENTS UNDERGOING CHIN LENGTHENING WITH INTERPOSITIONAL ALLOGENIC ILIAC BONE GRAFT

8

Patient Age Vertical Horizontal Follow-Up Number (yr) Gender Change (mm) Change (mm) (mo) 52 34

M M

8 7

2 2

12 12

3

39

F

7

2

13

4 5 6 7

33 25 27 48

M M F F

10 10 10 5

3 1 3 2

17 12 14 24

8

44

M

5

2

15

9

52

F

5

2

12

10

20

M

4

1

20

11 12

17 15

F F

5 5

1 1

12 12

13 14 15 16 17

44 58 48 45 17

F M F M F

6 6 6 6 6

3 2 2 1 2

14 12 12 12 12

18

16

F

6

1

12

19

23

F

6

3

12

short face, OSA primary mandibular deficiency primary mandibular deficiency short face, OSA short face, OSA short face, OSA primary mandibular deficiency, OSA maxillary deficiency with relative mandibular excess, OSA asymmetric mandibular excess, OSA maxillary deficiency with relative mandibular excess short face maxillary deficiency with relative mandibular excess short face, OSA short face, OSA short face, OSA short face maxillary deficiency with relative mandibular excess maxillary deficiency with relative mandibular excess short face, OSA

BSSO Le Fort I septoplasty turbinate reduction uvulectomy BSSO Le Fort I septoplasty turbinate reduction

none none

BSSO Le Fort I septoplasty turbinate reduction

none

BSSO BSSO BSSO BSSO

none none none none

Le Fort I turbinate reduction Le Fort I septoplasty turbinate reduction Le Fort I Le Fort I septoplasty turbinate reduction anterior neck lift BSSO Le Fort I

BSSO Le Fort I septoplasty turbinate reduction anterior neck none lift BSSO Le Fort I

none

BSSO Le Fort I septoplasty turbinate reduction exo BSSO Le Fort I septoplasty turbinate reduction

none none

BSSO BSSO BSSO BSSO BSSO

Le Fort I septoplasty turbinate reduction Le Fort I exo Le Fort I septoplasty turbinate reduction Le Fort I septoplasty turbinate reduction Le Fort I exo

none none none none none

BSSO Le Fort I septoplasty turbinate reduction exo

none

BSSO Le Fort I

none

Abbreviations: BSSO, bilateral sagittal split osteotomy; exo, extractions; F, female; M, male; OSA, obstructive sleep apnea. * Wound dehiscence, infection, fibrous union, or need for reoperation. Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

none

CHIN LENGTHENING WITH ALLOGENIC BONE GRAFT

1 2

Simultaneous Procedures

Diagnosis

Wound Healing Complications*

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POSNICK AND SAMI

a safe option when the surgeon finds that an interpositional graft is needed. This study confirms the safety of allogenic (iliac) corticocancellous grafting when used to fill interpositional defects associated with a transverse symphyseal osteotomy and chin lengthening.

References FIGURE 3. Vertical lengthening of the chin with an interpositional allogenic iliac bone graft. Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

with initial inherent structural strength, which weakens with resorption, eventually strengthening with bony deposition and organization.16,17,19 Potential complications associated with allogenic bone use include graft fracture, lack of integration with surrounding bone, and infection. In theory, a larger mass of allograft is said to be associated with increased risk of bacterial infection and nonunion. Transference of viral particles also is a potential concern.18 The present study patients did not develop any of these potential complications and all achieved the planned morphologic outcome at the chin region. This study does not address or attempt to resolve the questions of what size interpositional chin defect must be grafted and what material is the best to use when a graft is deemed necessary. The authors can confirm that allogenic iliac corticocancellous bone is

FIGURE 4. Horizontal advancement of the chin combined with lengthening and an interpositional allogenic iliac bone graft. Posnick and Sami. Chin Lengthening With Allogenic Bone Graft. J Oral Maxillofac Surg 2015.

1. Obwegeser HL: The surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. Part 1. Oral Surg 10:677, 1957 2. Posnick JC: Short face growth patterns: Maxillo-mandibular deficiency, in Posnick JC (ed): Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2013, pp 866–896 3. Posnick JC: Aesthetic consideration of the chin: Evaluation and surgery, in Posnick JC (ed): Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2013, pp 1564–1612 4. Burstone CJ: Lip posture and its significance in treatment planning. Am J Orthod 53:262, 1967 5. Finn RA, Bell WH, Brammer JA: Interpositioning grafting with autogenous bone and coralline hydroxyapatite. J Maxillofac Surg 8:217, 1980 6. Kim GJ, Jung YS, Park HA, et al: Long-term results of vertical height augmentation genioplasty using autogenous iliac bone graft. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100: e51, 2005 7. Rosen HM: Surgical correction of the vertically deficient chin. Plast Reconstr Surg 82:247, 1988 8. Freihofer HPM: Surgical treatment of the short face syndrome. J Oral Surg 39:907, 1981 9. Lye KW, Deatherage JR, Waite PD: The use of demineralized bone matrix for grafting during Le Fort I and chin osteotomies: Techniques and complications. J Oral Maxillofac Surg 66:1580, 2008 10. Herford AS, Dean JS: Complications of bone grafting. Oral Maxillofac Surg Clin North Am 23:433, 2011 11. Converse JM, Wood-Smith D: Horizontal osteotomy of the mandible. Plast Reconstr Surg 34:464, 1964 12. McBride KL, Bell WH: Chin surgery, in Bell WH, Proffit WR, White R (eds): Surgical Correction of the Dentofacial Deformities. Philadelphia, PA, Saunders, 1980, p 1210 13. Wessberg GA, Wolford LM, Epker BN: Interpositional genioplasty for the short face syndrome. J Oral Surg 38:584, 1980 14. Luhr HG (ed): Fortschritte der kiefer und gesichts-chirurgie. Stuttgart, Germany, Thieme Verlag, 1994, pp 1–13 15. Wolfe SA: Aesthetic procedures on the chin, in Regnault P, Daniel R (eds): Aesthetic Plastic Surgery. Boston, MA Little, Brown, 1984, p 221 16. De Long WG, McKee M, Watson T, et al: Bone grafts and bone graft substitutes in orthopaedic trauma surgery. J Bone Joint Surg Am 89:649, 2007 17. Garbuz DS, Masri BA, Czitrom AA: Biology of allografting. Orthop Clin North Am 29:199, 1998 18. Roden RD Jr: Principles of bone grafting. Oral Maxillofac Surg Clin North Am 22:295, 2010 19. Bhatt RA, Rozental TD: Bone graft substitutes. Hand Clin 28:457, 2012

Is It Safe and Effective to Lengthen a Chin With Interpositional Allogenic (Iliac) Graft?

This is a retrospective review of a consecutive series of patients undergoing chin lengthening at the time of orthognathic surgery over a 3-year timef...
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