Esthetically Driven Surgical and Prosthetic Management of Alveolar Distraction Osteogenesis
What is now proved was once only imagined.
Restoration of the partially edentulous maxilla with advanced vertical and horizontal deficiencies is a significant multidisciplinary challenge. The objectives of rehabilitation are at the same time both functional and esthetic. They should involve a realistic morphologic duplication of the original elements of the dentofacial complex and the restoration of harmonious relationships between those elements.1,2 The treatment should address osseous, dental, and implant-mucosal deficiencies. Esthetically driven objectives accomplished within sound biologic parameters should provide for the most predictable and stable treatment outcome.3
The initial concern is to establish a stable osseomucosal unit as the foundation for the implant- or tooth-borne prosthesis. Among the available surgical augmentation techniques (autogenous or synthetic bone; connective tissue or soft tissue grafts), most have shortcomings, thus frustrating restorative strategies with postoperative vertical, horizontal, and soft tissue deficiencies. These defects necessitate the utilization of long, esthetically compromised restorations, often modified with pink porcelain or short, unnaturally square teeth, when the dimension of grafted bone or connective tissue is excessive.
Jensen et al4 have confirmed that distraction osteogenesis within the osteoperiosteal flap is the most predictable of the grafting techniques designed to address the complex esthetic and functional deficiencies associated with severe anterior maxillary alveolar atrophy (see chapter 3). They reported the cases of 28 patients with anterior maxillary defects averaging 6.5 mm vertically and 2.0 mm horizontally. A restorative outcome index, scaled from 1 to 10, was tabulated for each case; in the scale, 1 was an extremely poor result, and 10 was a superlative esthetic result. Evaluations over the course of the study rated none of the results as superlative, but 16 of 25 were rated good esthetic outcomes.
Contributing to less than superlative results was a tendency for the osseomucosal segment to distract and heal asymmetrically, particularly horizontally. With the development of improved, bidirectional distraction elements, the ability to accurately position the maxillary osseomucosal segment has improved significantly, thus providing for more predictable osseomucosal segment positioning.5
The attendant prosthetic challenges are to provide a method to precisely locate the transported segment to a prescribed, preplanned, esthetically driven treatment position and to overcome traditional implant prosthetics–related problems of unstable postsurgical soft tissue levels and unpredictable gingival esthetics.
Proposed, in case report format, is an esthetically driven, staged prosthetic-surgical technique in which a series of custom provisional restorations are utilized as surgical guides for initially positioning the transported osseomucosal segment. These custom restorations are then used secondarily to surgically retrofit the definitive prosthesis to a precise, esthetically predetermined treatment position.
Case 1: Maxillary anterior edentulism coupled with severe alveolar atrophy and scar tissue
Presented is a challenging case of maxillary partial edentulism (canine to canine) complicated by severe, traumatically induced alveolar atrophy, failed conventional block graft and allograft attempts, and resultant implant failures. The ultimate surgical removal of (1) residual, fragmented expanded polytetrafluoroethylene barrier membrane, (2) residual allograft, and (3) malpositioned implants resulted in marked horizontal (9-mm) and vertical (11-mm) defects, irregular alveolar bone morphology, and significant soft tissue scarring (Fig 18-1). The described treatment approach is a staged, guided distraction osteogenesis within the osteoperiosteal flap, subsequently restored with an implant-supported prosthesis. The procedures are guided by a series of carefully executed provisional prostheses and surgical guides based on those prostheses (Box 18-1).
Box 18-1 Key components of esthetically driven surgical-prosthetic management of alveolar distraction osteogenesis
Stage 1: Distraction
- Fixed provisional prosthesis (FPP)
- Esthetic control cast (ECC)
Stage 2: Implant placement
- Implant surgical guide
- Implant-supported screw-retained provisional prosthesis
Stage 3: Retrofit provisional prosthesis
- Retrofit provisional (RFP) prosthesis
- Cosmetic surgical guide
Stage 4: Definitive prosthesis
- Custom implant abutments and prosthesis framework