Early osseointegration of electrodeposited calcium phosphate coatings on rabbits'femurs

Chen SUN; Yuchen WANG; Yining WANG; Jiawei WANG

ABSTRACT

BACKGROUND:

Electrochemically deposited coating, as an alternative method of plasma spraying coating, has arose widely attention, however, few reports concerning its in vivo biological features, especially the effect of coating on early osseointegration and duration of bone healing is poorly understood.

OBJECTIVE:

To investigate the early osseointegration of electrodepositied calcium phosphate and calcium phosphate/chitosan coatings on rabbits' femurs. DESIGN, TIME AND

SETTING:

An open experiment. The experiment was performed at the Key Laboratory for Oral Biomedical Engineering of Ministry of Education, Stomatology School of Wuhan University from April 2008 to May 2009. MATERIALS Eighteen male Japanese rabbits were supplied by the animals' center of Wuhan University. Ti_6Al_4V alloy was purchased from Baoji Titanium Nickel Co., Ltd. Chitosan with over 75% degree of deacetylation was produced by American Sigma Company.

METHODS:

① Cylindrical titanium alloy implants (3.3×8.0 mm) were designed with a gap (0.3×4.0 mm) in the middle part by using precision machine tool. The implants were prepared electrodeposited calcium phosphate coating surface (ELD group) and electrodeposited calcium phosphate/chitosan coating surface (ELDC group) with 2.5 mA/cm~2 electric current and 52 V temperature. Meantime, the implants with sandblasted surface were prepared as the control group. Totally 36 implants were randomly inserted into the distal femur condyles of 18 rabbits, and the new bone formation was labeled by fluorescence staining. MAIN OUTCOME

MEASURES:

At weeks 2 and 4 after operation, the implants were subjected to histological and histomorphometric analysis.

RESULTS:

All groups were observed different-quantity new bone formation. However, only ELDC group was seen fibrous tissues intervened at bone-to-implant interface. The ELD coatings were heterogeneously degraded, and the majority of the ELDC coatings were degraded. The new bone within gaps of ELD and control groups could be seen under the confocal laser scanning microscope with a continuous process of bone apposition. Percentages of bone-to-implant contact within and outside of the gaps of ELD group at weeks 2 and 4 were significantly higher than those of ELDC and control groups (P < 0.05). Bone formation rates of ELD group were significantly higher than those of ELDC group at weeks 2 and 4 after operation (P < 0.05).

CONCLUSION:

ELD implants can promote early osseointegration and induce bone tissue growth into the gaps; however, ELDC implants go against osseointegration of rabbit femurs.