Augmentation rib grafting to the inferior border of the atrophic edentulous mandible: A S-year experience

Bruce Sanders, D. D. S. ,* and John Beumer, III, D. D.S., M. S. ** University of California, Los Angeles, School of Dentistry, Los Angeles, Calif.

S everal surgical procedures have been proposed to cope with the problem of the severely atrophic

edentulous mandible.‘, ’ Regrettably, long-term results with these techniques are not very encour- aging.3 Recently, rib grafting to the inferior border of the mandible has been reported with promise of improved results. 3-6 The purpose of this article is to

discuss our experience with 31 inferior border rib grafts placed during the last 5 years.

INDICATIONS

Indications for rib grafting to the inferior border

of the mandible are augmentation of the severely atrophic edentulous mandible, prevention of patho- logic fracture in the severely atrophic edentulous mandible, and reduction and fixation (management) of nonunion or malunion fractures in the severely atrophic edentulous mandible.

ADVANTAGES

In our experience, the following advantages should be considered:’

1. The extraoral approach does not obliterate the vestibule as does the intraoral onlay technique. This enables the patient to wear a relined interim man-

dibular denture relatively soon after grafting and after surgical edema subsides.

2. We have not encountered problems of mucosal dehiscence with this technique. This is a major problem with intraoral superior border approaches because substantial loss of graft material usually

results. 3. There is little orofacial pain with this tech-

nique. Patients can take oral fluids and food without

risk of damage or contamination of the wound.

Presented before the Pacific Coast Society of Prosthodontists,

Monterey, Calif. *Associate Professor, Section of Oral and Maxillofacial Surgery. **Professor and Director, Maxillofacial Prosthetics.

16 JANUARY 1982 VOLUME 47 NUMBER 1

4. The inferior border technique does not appear to alter vertical dimension of occlusion and, conse- quently, the interocclusal space remains unaltered. Large blocks of bone,onlayed to the superior surface

of the mandible may encroach upon or obliterate this space.

5. Secondary lingual vestibuloplasty is not neces- sary in many patients since the mylohyoid muscles are repositioned below the rib graft during wound

closure at the initial surgery. 6. The inferior border approach provides excel-

lent stabilization of bilateral body fractures in the severely atrophic edentulous mandible. Undesirable displacement of the proximal and distal fragments

common in other forms of fixation is not a problem. Splints or intermaxillary fixation are unnecessary (Fig. 1).

7. Bone resorption rates appear acceptable, at least for the short term, presumably because there

are no direct forces to the rib grafts. (An evaluation of resorption rates will be presented in a follow-up study that has not yet been published.)

8. In patients where a skin graft vestibuloplasty

had already been performed and more bony resorp- tion had occurred, an inferior border rib graft can be done without disturbing the skin graft.

9. In patients with an existing subperiosteal implant in good condition, but where the mandible is so atrophic that pathologic fracture is imminent or

has actually occurred, inferior border rib grafting can be used to salvage the implant and reinforce the mandible (Fig. 2).

10. The inferior border rib grafting procedure can be used for augmentation in “pencil-thin” atrophic edentulous mandibles where interpositional grafts or visor osteotomies are not feasible.

11. Skin graft vestibuloplasty is a much easier

procedure to perform with the bone graft on the inferior border than with the graft on the superior surface of the mandible.

0022-3913/82/010016 + 07$00.70/O @ 1982 The C. V. Mosby Co.

INFERIOR-BORDER RIB GRAFTING

Fig. 1. Management of nonunion fractures of severely atrophic edentulous mandible can be treated successfully with rib grafting to inferior border, resulting in stabilization of fracture without using splint suspension or intermaxillary fixation. Mandible will also be augmented to minimize risk of future pathologic fractures. A, Nonunion fracture of left body of atrophic edentulous mandible. Routine fixation principles of splint suspension and intermaxillary fixation were ineffective. B, Inferior border rib grafting stabilized nonunion fracture and augmented atrophic mandible. C, Four and one-half years postoperatively. Note that fracture is completely healed and resorption of graft is minimal.

THE JOURNAL OF PROSTHETIC DENTISTRY 17

SANDERS AND BEUMER

Fig. 2. Existing acceptable subperiosteal implant, but mandible is so atrophic that pathologic fracture may be imminent. Inferior border rib grafting can be used to salvage implant and reinforce mandible. A, Subperiosteal implant placed 4 years previously in 2%year-old woman.

Placement was precipitated by severely atrophic mandible; however, mandible was so thin that patient complained of deficient lower one-third facial deformity. Rib graft augmentation to inferior border of mandible served to prevent pathologic fracture and increase lower face height. B, Mandibular infeiior border exposed. C, Rib grafts placed and stabilized. D, Postoperative panoramic radiograph showing augmentation of mandible with inferior border grafts. Patient shown 2 years postoperatively.

DISADVANTAGES

As with all procedures, there are definite disad- vantages to the inferior border rib grafting tech- nique:

1. This procedure requires a large extraoral inci- sion, with resultant scarring; however, good judg- ment and careful surgical technique will ensure an acceptable cosmetic result in most patients. I f the patient does not have redundant loose submandibu- lar and submental soft tissues to accommodate the rib graft placement, facial appearance may be adversely altered. Prior to the procedure, all patients should be informed of the potential changes in lower facial contours.

2. The procedure does not correct any superior border irregularities. For example, a painful mental

nerve will not be corrected by this procedure. How- ever, the mental nerve can be repositioned, and superior surface bony irregularities can be corrected with a minor alveoloplasty.

TECHNIQUE

A length of 15 to 20 cm is required for each rib (Fig. 3). The inner surface of the ribs are scored with a fissure bur, and the cortical segments are removed with an osteotome and mallet. This aids in bending the ribs to match the contour of the mandible (Fig. 4). The cortical segments removed are stored for later use. The inferior border of the mandible is exposed

by means of a bilateral, continuous, submandibular incision (Fig. 5). One rib is abutted against the lingual aspect of the inferior border, the other

18 JANUARY 1982 VOLUME 47 NUMBER 1

INFERIOR-BORDER RIB GRAFTING

Fig. 3. Preparation of rib grafts. A, Required length for each of two ribs is 15 to 20 cm. 8, Scoring inner surface of ribs. C, Inner cortical segments are removed with osteotome and mallet. D, Cortical chips are also stored for packaging between ribs.

Fig. 4. A and B, Using finger pressure, ribs may be shaped into desired contour.

Fig. 5. A and B, Submandibular approach to exposing inferior aspect of mandible.

THE JOURNAL OF PROSTHETIC DENTISTRY 19

SANDERS AND BEUMER

Fig. 6. Fixation of ribs to inferior border of mandible. A, Placement of intraosseous wires for fixation of ribs. B and C, Securing of rib grafts to buccal-inferior and lingual-inferior aspect of mandible a;ld packing of bone chips between ribs to increase thickness of inferior border graft.

Fig. 7. Wound closure.

against the buccal aspect of the inferior border. The space between the two ribs is filled with the cortical segments removed during preparation of the ribs. The ribs are fixed into position with both circumfer- ential and intraosseous wiring (Fig. 6). Wound

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closure is performed in the conventional surgical manner (Fig. 7).

RESULTS

To date, 31 patients have undergone inferior border rib grafting. Eighteen patients were treated for augmentation of atrophic edentulous mandibles, and five were treated to prevent an anticipated pathologic fracture in severely atrophic “pencil-

thin” mandibles (Fig. 8). Eight patients were treated to stabilize nonunion or malunion fractures of atro- phic edentulous mandibles. In fracture patients, augmentation was carried out in addition to stabili- zation.

The follow-up observation period has ranged from

6 months to 5 years: one patient for 5 years, two for 4 years, six for 3 years, 13 for 2 years, six for 1 year, and three for 6 months.

Six months after inferior border rib grafting, most of the patients underwent skin graft vestibuloplasty.

JANUARY 1982 VOLUME 47 NUMBER 1

INFERIOR-BORDERRIBGRAFTING

THE

Fig. 8. Patient unable to wear satisfactory lower denture due to severely atrophic edentulous mandible complicated by presence of titanium tray placed several years previously to stabilize bilateral fractures. It was necessary to remove tray prior to any new prosthesis construction; however, tray removal could result in pathologic fracture. To prevent fracture and further augment mandible, it was decided to perform an inferior-border rib graft. A, Facial appearance prior to inferior-border rib grafting. Note deficient lower one-third facial appearance. B, Panoramic radiograph showing atrophic edentulous mandible with titanium mesh tray in place, used in conjunction with cancellous iliac crest graft to treat bilateral nonunion fracture. C, Intraoral view showing lack of vestibule. Tray was palpable intraorally, preventing construction of satisfactory prosthesis, Following tray removal, inferior border rib grafting was used to prevent pathologic fracture during and after surgery. D, Six months after rib grafting, skin graft buccal vestibuloplasty was performed. Lingual vestibuloplasty was not needed due to increase in depth of floor of mouth from rib grafting procedure. E and F, Mandibular prosthesis after mandibular reconstruction. Note extended lingual flanges secondary to deep lingual vestibule accomplished by inferior border grafting. G, Five-year postoperative panoramic radiograph of patient shows no evidence of significant resorption of graft. II, Five-year follow-up view of mandibular alveolar ridge. Note excellent denture-bearing area. I, Five-year facial view. Note improved lower facial contour.

21

SANDERS AND BEUMER

Several patients did not require lowering of the floor of the mouth because of the increase in the depth of

the lingual sulcus that resulted from the reattach- ment of the mylohyoid muscle underneath the rib graft. Two patients did not require vestibuloplasty, and one patient did not need further treatment. At the time this report was prepared, all patients were wearing their dentures satisfactorily. Patient ap- praisal of this procedure has been positive, and bone

resorption rates appear to be minimal or moderate. There have been only a few complications. One

patient developed a minor soft tissue infection fol-

lowing removal of wire, although no bone loss occurred. Another patient presented with soft tissue infection at the symphysis, and significant bone loss was noted; however, vestibuloplasty and prosthesis construction were carried out successfully.

SUMMARY

Inferior border rib grafting appears to be a useful procedure in providing bony augmentation for severely atrophic edentulous mandibles. Major advantages to the prosthodontic patient are that (1)

remodeling and changes in the denture-bearing surfaces are minimal following surgery, (2) the inter- occlusal space is unaltered, (3) in nonunion body

fracturs occurring in severely atrophic mandibles, the ribs applied to the inferior-buccal and inferior- lingual aspects of the mandible hold the fragments in a much more favorable position, thus preventing superior elevation of the posterior segment and

inferior displacement of the anterior segment, and

(4) resorption rates seem acceptable. The patient should be informed of possible conse-

quences. As with all preprosthetic special procedures, a psychosocial analysis may also be indicated.

We are grateful to Drs. D. Adams, H. Davis, R. Halliday, M. Malkassian, S. Poidmore, and W. Stephens for sharing their thoughts and experiences with the inferior border rib grafting

technique.

REFERENCES

1.

2.

3.

4.

5.

6.

7.

Boyne, P. J.: Autogenous cancellous bone and marrow transplants. Clin Orthop 73:199, 1970.

Davis, W. H., Weiner, J. R., and Terry, B.: Transoral bone graft for atrophy of the mandible. J Oral Surg 28:760,

1970. Davis, W. H., Delo, R. I., Ward, W., Terry, B., and Patakas, B.: Long-term ridge augmentation with rib grafts. J Maxil-

lofac Surg 3:103, 1975. Sanders, B., and Cox, R.: Inferior border rib grafting for

augmentation of the atrophic edentulous mandible. J Oral

Surg 34:897, 1976. Sanders, B.: Rib grafting to the inferior border of the

mandible. J Oral Surg 36:669, 1978. Sanders, B., and Firtell, D.: Reconstructive preprosthetic

surgery. In Beumer, J., Curtis, T. A., and Firtell, D., editors: Maxillofacial Rehabilitation: Prosthodontic and Surgical

Considerations. St. Louis, 1979, The C. V. Mosby Co. Beumer, J.: Complete dentures for patients with mandibular

inferior border rib grafts. J Oral Surg 37:301, 1979.

Reprint rep&s to: DR. BRUCE SANDERS

UNIVERSITY OF CALIFORNIA

Sc~oca OF DENTISTRY

Los ANGELES, CA 90024

22 JANUARY 1982 VOLUME 47 NUMBER 1