Failure to induce supracrestal bone growth between and around partially inserted titanium implants using bone morphogenetic protein (BMP): an experimental study in dogs

Abstract

The effect of bone morphogenetic protein on supracrestal bone growth around partially inserted implants in a dog model is described. The lower premolar teeth (P1, P2, P3 and P4) were extracted on both sides of the mandible in six dogs. At a surgical exposure 12 weeks later, two 10-mm turned titanium implants were partially inserted, approximately 15 mm apart, in the areas of the P1 and P3 in each side of the mandible, allowing five threads to protrude from the bone crest. A titanium mesh was fastened to the coronal aspect of the two fixtures and the space beneath the mesh was filled with bone morphogenetic protein (S300 BMP) in combination with an insoluble bone matrix carrier, or with the carrier alone. The mesh was covered with an ePTFE membrane. Thus, a space for potential bone formation was created between the two implants. The surgical flaps were coronally positioned and secured with vertical mattress sutures. After 16 weeks of healing, biopsy specimens were retrieved and examined histologically. Bone was not formed around the protruding implants or in the created space between the implants in any case. The carrier was incompletely resorbed. We conclude that supracrestal bone growth beyond the crestal limit with or without BMP in such a large space as in this experimental design may not be possible.

Clinical outcomes of vertical bone augmentation to enable dental implant placement: a systematic review

“…Four papers within the total 18 studies described GBR by means of an e‐PTFE membrane and blood clot in a one‐stage procedure. Two of them (Simion et al 1994, Jovanovic et al 1995) reported a significant mean vertical bone gain in respect to the control sites, whereas the other two papers (Roos‐Jansåker et al 2002, Stenport et al 2003) failed to demonstrate such a difference compared with the controls.…”

Peri-implant reactivity and osteoinductive potential of immobilized rhBMP-2 on titanium carriers

“…In subsequent pilot experiments in dogs with immobilized rhBMP-2 (0.60-0.80 lg cm À2 ) on dental implants a significant increase in peri-implant bone density was also indicated in the tiba but not in the mandible [37]. Work by other groups on peri-implant bone formation in vivo by rhBMP-2 applied together with diverse carriers has achieved varied degrees of success or has failed [38][39][40][41]. These unsatisfactory results indicate that the biochemical and physicochemical mechanisms underlying bioactive BMP-2 coatings are still only poorly understood.…”

“…Advantages of the implant immobilized rhBMP-2 are: (i) the easy delivery of rhBMP-2 with a homogeneous distribution on the implant surface; (ii) the primarily circumferential bone induction; (iii) the rapid gap filling by trabecular bone within 4 weeks; and (iv) the easier control and avoidance of ectopic bone formation. Why others have found it difficult to obtain similar results [37][38][39][40][41] remains unclear. We feel that a comparability of experiments among groups will only be possible if all decisive parameters (e.g.…”

The enhancement of osteogenesis by nano-fibrous scaffolds incorporating rhBMP-7 nanospheres

“…The properties of carriers, including material type, geometry, porosity, and pore size, are critical determinants both for the delivery of BMPs and the subsequent success of bone regeneration [37][38][39]. In bone tissue engineering, the ideal delivery system should serve two primary roles: as a delivery carrier to maximize the osteogenic effect of BMPs by maintaining the bioactivity and duration of BMPs at implantation site with an optimal release profile; and as an osteoconductive scaffold with suitable pore structure for vascularization and bone formation.…”