Reconstruction of Severely Atrophic PreMaxilla using rhBMP-2 and Titanium Mesh for Dental Implants : a Case Report

In order to achieve functional and esthetic oral rehabilitations, dental implants must be placed at an ideal tridimensional position in the alveolar bone. A clinical case is presented of a 49-year-old female with a severely resorbed pre-maxilla. Bone augmentation was conducted using the “tent pole” technique with human recombinant morphogenetic bone protein-2 embedded in an absorbable collagen sponge and deproteinized bovine bone. In addition, a titanium mesh was adapted over the graft to provide support. At 8 months postop, a cone beam computerized tomography (CBCT) scan showed significant bone consolidation. An ideal premaxilla ridge with more than 14 mm of vertical and 10 mm of horizontal width was observed. Four dental implants were placed. Re-entry was 6 months later. Individual crowns were made to substitute the incisors, which were in function for the 1-year follow-up. J O U R N A L O F D E N T A L A N D O R A L I M P L A N T S ISSN NO: 2473-1002 CASE REPORT DOI : 10.14302/issn.2473-1005.jdoi-15-742 Corresponding author: Cimara Fortes Ferreira, DDS, MSc, PhD, Assistant Professor Director of Implant Dentistry, University of Tennessee School of Dentistry Department of Periodontology, 875 Union Avenue Dunn Dental Building Memphis TN 38163, Phone: (901) 448-4494, Fax: (901) 448-6751, Email: cferreir@uthsc.edu. Running title: rhBMP-2 for pre-maxilla reconstruction.


Introduction
The use of dental implants for oral rehabilitations has become a routine procedure in the practice in dentistry.
An increasing number of fully and partially edentulous patients seek this type of rehabilitation for the advantage of being a fixed and conservative solution to the tooth loses. Dental implants must be planned and placed at the best tridimensional position in the alveolar process in order to restore masticatory and phonetic functions, in addition to esthetics. For this purpose, the treatment plan is governed primarily by the prosthetic design. 1  The human recombinant morphogenetic bone protein 2 (rhBMP-2) is a growth factor associated with the proliferation of mesenchymal cells and their differentiation into osteoblasts. 5 rhBMP-2 is the most researched and published bone growth factor and has shown to be of great importance in the success of bone reconstruction procedures. The use of rhBMP-2 has been used for augmentation of: clefts 6 , experimental critical-size defects 7 , continuity or mandibular alveolar bone defects 3 and sinuses. 8 All these studies have shown biologically the role of rhBPM-2 on bone formation and pointed out that its clinical use can be an alternative to autogenous bone graft in some clinical situations.
Few studies have used rhBMP-2 for rehabilitation of the atrophic pre-maxilla. The objective of this case study is to present an alternative technique to autogenous bone graft to reconstruct a severely absorbed pre-maxilla using rhBMP-2 associated with lyophilized bone graft and titanium mesh.

Case report
A 49-year-old female presenting a severely resorbed pre on the palatal aspect of the ridge, respecting a 2 mm distance from the mesh to the adjacent teeth (Fig. 5).
Extensive undermining incision was conducted on the apical aspect of the buccal flap in order to achieve primary closure.
At the 8-months follow-up, a CBCT scan showed consolidation of the grafted material with the recipient bone (Fig. 6). A second surgical procedure was conducted under local anesthesia and oral sedation in order to remove the titanium mesh. At this appointment, the pre-maxilla showed to be significantly augmented ( Fig. 8) with the dimension of 14 mm in height and 10 mm in width. The bone characteristics were soft, erythematous, with a cancellous texture. Four dental implants (Biomet 3I certain ® , USA) were inserted, with no more than 25 Ncm 2 of primary stability (Fig. 8). The implants were uncovered 6 months later for initiation of the prosthetic rehabilitation using 4 single-unit crowns.
One-year follow-up showed to be uneventful (Fig. 9).     Vertical distraction osteogenesis could have been a treatment option for this case to restore the lost     This case demonstrated the high potential of rhBMP-2 for bone reconstruction.
ACS is 90% air, which is an inadequate scaffold in larger-volume defects. 13 In large defect reconstructions, especially for vertical augmentation, a scaffold is necessary for bone formation. Because of these requirements, a natural bone mineral component derived from bovine bone and a titanium mesh were used. The proposed technique proved to be a successful due to the scaffold serving for bone formation which extended beyond the limitations of the titanium mesh.
In addition, the natural bone mineral component derived from bovine bone was used to promote a higher bone density due to its higher osteocondutive potential.
The reconstructive technique presented showed to be successful in the augmentation of severely atrophic pre-maxilla for the rehabilitation with dental implants. Further studies are necessary to verify if the success obtained in this clinical case is statistical significance.