Bone response to three different dental implant surfaces with Escherichia coli-derived recombinant human bone morphogenetic protein-2 in a rabbit model

Abstract

Purpose: The objective of this study was to analyze orthotropic bone formation/remodeling of three different dental implant surfaces with/without recombinant human bone morphogenetic protein-2 derived from Escherichia coli (ErhBMP-2) in a rabbit model. Materials and Methods: Resorbable blasting media (RBM), sandblasted large grit and acid-etched (SLA), and Mg-incorporated oxidized (MgO) surfaces were coated with ErhBMP-2 (1.5 mg/mL). The implants were placed into the proximal tibia in six New Zealand White rabbits. Each rabbit received six different implants (three coated with ErhBMP-2 in one tibia and three uncoated implants in the other tibia) and the sites were closed submerging the implants. The animals received alizarin (2-week), calcein (4-week), and tetracycline (6-week) fluorescent bone markers; they were euthanized at 8-week for histomorphometric analysis.Results: Amount of coated ErhBMP-2 was 9.6±0.4 μg/MgO, 14.5±0.6 μg/RBM, and 29.9±3.8 μg/SLA per implant. Clinical healing was uneventful. Considering the entire implant, mean bone-implant contact (±SD) for the ErhBMP-2/RBM (35.4±5.1%) and ErhBMP-2/MgO (33.4±13.2%) implants was significantly greater compared with RBM (23.6±6.2%) and MgO (24.9±2.7%) implants (p<0.05). However, ErhBMP-2/SLA implants (19.1±7.2%) showed slightly lower bone-implant contact compared with SLA implants (23.4±3.8%; p > .05). Considering mean bone-implant contact in cortical bone and bone area within the threads, there were no significant differences between ErhBMP-2 coated and uncoated RBM and MgO implants. ErhBMP-2/SLA implants (32.9±7.8%) showed lower bone-implant contact than all other implant variations (range 39.9±18.1% - 51.3±9.2%; p < .05). Similarly there were no remarkable differences in new bone area with minor differences between implants. Conclusions: Within the limits of this study, absorbed ErhBMP-2 dose varies with implant surface characteristics in turn influencing local bone formation/remodeling.