Alveolar ridge augmentation using anodized implants coated with Escherichia coli–derived recombinant human bone morphogenetic protein 2

Abstract

The aim of this study was to examine the effect of Escherichia coli-derived recombinant human bone morphogenetic protein 2 (ErhBMP-2) coated onto anodized implant to stimulate local bone formation, including osseointegration and the vertical augmentation of the alveolar ridge. Six young male adult beagle dogs were used. A crestal area was leveled on both sides of each test subject by removing minimal cortical bone using a round bur and without exposing cancellous bone. After a 2-month healing period, 3 anodized implants (length 8 mm, diameter 4 mm; Cowellmedi, Busan, Korea) were placed 5 mm into the mandibular alveolar ridge in either side. Each animal received 6 implants that were either coated with ErhBMP-2 (0.75 or 1.5 mg/mL concentration; Cowellmedi) or uncoated. This was performed using a randomized split-mouth design. A total of 36 implants were used for this study. Twelve noncoated implants were used as control, and 24 BMP-coated implants were used as our experimental group, which was further divided into 2 groups of 12 implants each with different BMP concentration of 0.75 and 1.5 mg/mL. Radiologic examinations were performed immediately after implant placement and 4 and 8 weeks after implant placement. The amount of bone augmentation was evaluated by measuring the distance from the uppermost point of the cover screw to the marginal bone. Implant stability quotient (ISQ) values were measured immediately after surgery and 8 weeks after implant placement. Statistical analysis was performed using one-way analysis of variance (SPSS version 17.0) and multiple-comparison tests. Statistical significance was established at the 95% confidence level. Implants coated with ErhBMP-2 at 0.75 mg/mL (BMP 0.75 group) and 1.5 mg/mL (BMP 1.5 group) exhibited significant vertical bone formation compared with the control group (mean ± SD): 0.88 ± 0.94 versus 0.60 ± 0.64 versus -0.52 ± 0.64 mm, respectively; P < .05. There was a significant difference between the 3 groups in bone level change (P < .05). The BMP 0.75 and BMP 1.5 groups exhibited significant changes in ISQ compared with the control group: 8.17 ± 8.31 versus 11.50 ± 9.02 versus 2.17 ± 7.61, respectively; P < .05. Within the limits of this study, the ErhBMP-2 coating on an anodized implant may stimulate vertical bone augmentation, which significantly increases implant stability on completely healed alveolar ridges.