Nano-hydroxyapatite/collagen composited with recombinant human bone morphogenetic protein-2 and titanium membrane in repairing peripheral bone defects of instant dental implants

Bing LIU; Peng CHEN; Zhongyi WANG; Jie KE; Xiaohua LI; Zhengwen WANG

ABSTRACT

BACKGROUND:

Recently,with the rapid development of material science and bioscience,the technology of dental implant has made great progress,especially the immediate implant technology.But the size and shape of implant are usually not fit for tooth extraction wound,so it is an important factor that leads to failure when implant and tooth extraction wound can not form close tangency.Guided bone regeneration or bone grafting materials are usually used to solve this problem.

OBJECTIVE:

To study the effects of nano-hydroxyapatite/collogen (nHAC) with recombinant human bone morphogenetic protein-2(rhBMP-2) and titanium (Ti) membrane on repairing peripheral bone defects of instant implant.DESIGN,TIME AND

SETTING:

A randomized,controlled animal study was performed at the Central Laboratory,the Fourth Military Medical University of Chinese PLA between January 2005 and January 2006.MATERIALSTi screw implants (diameter 2 mm,length 10 mm,and pitch 0.4 mm) without the part that went through gum were offered by Nonferrous Metal Academy in Baoji,China.The nonabsorbable Ti membranes (2 cm×2 cm) were offered by Zhongbang Biomaterial Limited Company in Xi'an,China.The nHAC materials were gifted by professor Cui Fu-zhai from Material Science and Engineering Department of Tsinghua University and fabricated into 0.5 mm×0.5 mm×0.5 mm small blocks.rhBMP-2 was offered by the Academy of Military Medical Sciences in Beijing,China.rhBMP-2 was dissolved with hydrochloric carbamidine and then nHAC was immersed in it.Vacuumization,freeze-drying,and Ekibon degermation were followed.Each gram of nHAC compounds required approximately 1 mg rhBMP-2.

METHODS:

Four healthy purebred male dogs were included in this study.According to the methods to repair bone defects rhBMP-2+Ti membrane,nHAC composited with rhBMP-2 was implanted,covering Ti membrane.Six defects were made on the mandible on each side.MAIN OUTCOME

MEASURES:

At 6 and 12 weeks after implantation,new bone formation and the correlation of new bone to Ti implant were investigated by radiography,bone density measurement and histological examinations.

RESULTS:

All the bone wounds were full of new bone at 12 weeks,the Ti implants were steady and the osseointegration was good.In the nHAC+rhBMP-2 and nHAC+rhBMP-2+Ti membrane groups,new bone formed and maturated earlier.In the nHAC +Ti membrane,blank control,and nHAC + rhBMP-2 +Ti membrane groups,new bone formed well below Ti membrane and the alveolar crest was plump.In the nHAC + rhBMP-2 +Ti membrane group,new bone formed earliest with the most quantity and the alveolar crest was the plumpest.By 12 weeks,the bone density had achieved the same level as the autologous cancellous bone transplantation,but the alveolar crest was plumper compared to the positive control group.In addition,bone mass was much more.Bone formed slowest in the blank control group and fastest in the positive control group with the crest of ridge being slightly absorbed.

CONCLUSION:

nHAC is a new good bone graft material in repairing peripheral bone defects of instant implant,especially compositing with rhBMP-2 and/or Ti membrane.A round method to repair the surrounding bone defect of instant implant should be selected according to the specific situation in the clinic.