J Oral Maxillofac Surg 53:88-90, 1995

Autogenous Mandibular Bone Grafts for Malar Augmentation

JOHN JENSEN, DDS,* OSCAR REICHE-FISCHEL, DDS,~r AND STEEN SINDET-PEDERSEN, DDS, DR MED ScI~:

Flatness of the midfacial region secondary to sagittal maxillary and malar deficiency gives an older, expres- sionless, and sadder look to the patient. 1.2 The affected area usually extends from the base of the maxillary alveolar process to the infraorbital foramen, sometimes affecting also the paranasal and canine fossa to varying degrees. When this deformity is present, the preopera- tive analysis of the patient should include evaluation from the top, frontal, and profile views to estimate the extent of the maxillary deficiency and to which degree it eventually involves the zygomatic and infraorbital regions. As guidelines for surgical planning, it has been reported that the supraorbital ridges should project 4 to 8 mm anterior to the anterior surface of the cornea. The highlight of the malar eminence, which is the most prominent part of the zygomatic complex, should pro- ject slightly beyond the cornea. 1

The surgical treatment of severe midfacial deformity can be accomplished by high Le Fort I, Le Fort II, Le Fort III, or malar bone osteotomies, by masking the deformity with autogenous onlay bone or cartilage grafts, alloplastic materials such as Proplast (Vitek Inc., Houston, TX) Silastic (Dow Coming, Midland, MI), and hydroxylapatite, or by combination of these methods. 1-6 However, the esthetic and functional mani- festations of maxillary retrusion associated with malar deficiency can also be effectively treated by a Le Fort I osteotomy with simultaneous augmentation of the infraorbital and malar regions by using autogenous mandibular onlay grafts.

The following article describes a technique using autogenous mandibular bone from the chin or ramus

area for malar bone augmentation in cases with com- bined zygomatic and maxillary deficiency in the sagit- tal plane.

Technique

The circumvestibular incision of the Le Fort I osteot- omy is used for exposure of the malar bones, zygo- matic arches, and infraorbital areas. The subperiosteal dissection is extended superiorly and laterally across the malar eminence. Then, the infraorbital rim medial and lateral to the infraorbital nerve is meticulously exposed. The bony cuts of the Le Fort I osteotomy are performed and the maxilla down-fractured and secured

* Staff, Department of Oral and Maxillofacial Surgery, Aarhus University Hospital, Aarhus, Denmark.

t Visiting Resident from The University of Texas Health Science Center at Houston, TX.

:~ Professor and Chairman, Department of Oral and Maxillofacial Surgery, Aarhus University and University Hospital, Aarhus, Den- mark.

Address correspondence and reprint requests to Dr Jensen: Depart- ment of Oral and Maxillofacial Surgery, Aarhus University Hospital, Norrebrogade, DK-8000, Aarhus C, Denmark.

© 1995 American Association of Oral and Maxillofacial Surgeons

0278-2391/95/5301-002053.00/0

FIGURE 1. Autogenous mandibular bone graft specimens. A, Ex- cess bone removed from distal aspect of the proximal segment after sagittal split osteotomy performed for mandibular set-back. B, Chin bone obtained after reduction genioplasty. The bone is cut in similar sizes to obtain symmetrical results.

88

JENSEN, REICHE-FISCHEL, AND SINDET-PEDERSEN 89

FIGURE 2. Intraoperative view showing fixation of the autogenous mandibular onlay graft with one bone screw. A notch was made at the superior border of the graft to allow the infraorbital nerve to exit from the foramen and to prevent any pressure against it.

in the new position by rigid fixation. Intraorally, the infraorbital and malar bone regions are evaluated to estimate the graft size and thickness necessary to pro- ject the malar eminence slightly beyond the cornea. The autogenous bone grafts may be obtained from two sources in the mandible: 1) the mandibular symphy- sis, 7'8 and 2) the distal portion of the proximal segment of the mandibular ramus, if the patient is simultane- ously undergoing a set-back procedure using sagittal split osteotomies. In cases where reduction genioplasty is necessary, the wedge of bone removed from the

mandibular chin region also can be contoured into ap- propriate sizes to obtained the desired onlay grafts (Fig 1).

Placement of the onlay bone grafts is done after contouring, ensuring maximal bone contact against the malar and maxillary bones and eliminating sharp edges around the grafts. It should be verified that the graft exerts no pressure against the infraorbital nerve. If nec- essary, a notch is made in the superior border of the graft to accommodate the nerve. The grafts are fixed by placing one or two countersunk low-profile osteo- synthesis screws (Fig 2). The procedure can be per- formed alone as well as in conjunction with a low- level Le Fort I osteotomy.

Discussion

Nine patients (five females and four males) have been treated with this technique (age, 17 to 46 years; mean, 30 years). Seven patients had malar onlay grafts in combination with a low-level Le Fort I osteotomy, and two patients underwent placement of the malar onlay grafts during the correction of other craniofacial disorders. The follow-up period of up to 12 months showed one patient with palpable screws after partial resorption of one graft. The other eight cases showed no complications and satisfactory esthetic results post- operatively (Fig 3).

The length of the hospitalization is determined by the primary surgical procedure and is not increased

FIGURE 3. A, Preoperative and, B, postoperative cosmetic results obtained by malar augmentation grafting with mandibular onlay bone grafts applied simultaneously with a Le Fort I and bilateral sagittal split osteotomies.

90 AUTOGENOUS MANDIBULAR BONE GRAFFS

by morbidity f rom the donor site in the mandible. In addition, the incision and subsequent scar is hidden intraorally. Alloplastic materials such as Silastic (Dow Coming Corp, Midland, MI) or Proplast (Vitek, Hous- ton, TX) in different shapes and sizes also have been used for the same purpose, but complications like host reaction, migration, and displacement of the implant causing unesthetic and asymmetric results have been reported with the use of these materials. 1'2'6 Other sources o f autogenous or alloplastic bone material have been used and suggested in the literature for midfacial contouring. The morbidity associated with harvesting the graft in cases o f iliac, tibia, and fibula grafts, and the experimental and clinical evidence showing unpre- dictable resorption of endochondral grafts, outweigh their use for onlay purposes.I'2'4'8'9 Calvarium, however, represents a good source of membranous bone, but possibility of neurologic sequelae, with potential sub- dural hematoma, is present. 4

The use of mandible as an autogenous donor site has several advantages; it is a membranous bone, and experimental and clinical studies have shown that it tends to resorb less than endochondral grafts when used as onlay material. 71° Although one patient had partial resorption of one graft a year after placement, a satisfactory infraorbital-malar prominence was main- tained in all patients.

The technique proposed for mandibular onlay bone grafts and malar augmentation is simple, provides the advantages o f using an autogenous material, and re- quires no special instrumentation. Preliminary results with the small sample of patients included in this study

have indicated that satisfactory cosmetic results can be achieved 1 year postoperatively. However, additional data are necessary to assess the long-term prognosis of this procedure.

References

1. Bell W: Malar midfacial augmentation, in Bell W (ed): Modern Practice in Orthognathic and Reconstructive Surgery, vol 3. Philadelphia, PA, Saunders, 1992, pp 2289-2297

2. Bell W, Proffit WR, Jacobs JD: Anteroposterior, transverse (hor- izontal) and vertical maxillary deficiency, in Bell W, Proffit WR (eds): Correction of Dentofacial Malformations, vol 1. Philadelphia, PA, Saunders, 1980, pp 444-683

3. Epker BN, Wolford LM: Middle-third facial osteotomies: Their use in the correction of acquired and developmental dento- facial and craniofacial deformities. J Oral Surg 33:491, 1975

4. Harsha BC, Turvey TA, Powers SK: Use of autogenous cranial bone grafts in maxillofacial surgery: A preliminary report. J Oral Maxillofac Surg 44:t 1, 1986

5. Holmes RE, Wardrop RW, Wolford LM: Hydroxyapatite as a bone graft substitute in orthognathic surgery: Histologic and histometric findings. J Oral Maxillofac Surg 46:661, 1988

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10. Jensen J, Sindet-Pedersen, S: Autogenous mandibular bone grafts and osseo-integrated implants for reconstruction of the severely atrophic maxilla: A preliminary report. J Oral Maxil- lofac Surg 49:1277, 1991