New Developments in Plasma Spray

INTRODUCTION: for some orthopaedic and dental implants osseointegration is an essential outcome. In clinical applications there are many surface treatments able to improve osseointegration. Among them plasma spray (PS) coatings may be effective surface treatments with wide and well documented evidence of long term positive results. In other clinical cases a further step in osseointergation, i.e. bone ingrowth, is considered an essential benefit. Such a feature can be accomplished as ex. with large size and interconnected porous metal structures. So far beads sintering and porous scaffold welding are used to coat solid metal parts with large size porous structures with clinically established results. Also these methods, however, are not without drawbacks. High temperature, difficulties in coat complex shapes and high cost affect these processes.

Recently new key developments in Plasma Spray technology permit use this industrial process for applying highly porous titanium structures, with large size pores and interconnected porosity.

Titanium (Ti) coatings, i.e. Ti-Growth^®, are presented.

MATERIALS & METHODS:

Coatings developed were characterised by mechanical testing (adhesion, shear and  abrasion), image analysis (SEM), in vitro (cells vitality and proliferation) and in vivo investigations (implantation in animal studies).

RESULTS: Ti-Growth^® presents open and interconnected pores in the range 100-800µm, porosity between 40-70% with pores and  interconnections diameters around 300µm (Fig.1). Adhesion exceeds 35 MPa and debris release is lower than 65 mg after 100 cycles during Taber test.

In vitro tests highlighted cells capability to colonize large pore size structures (Fig. 2).

In vivo tests confirmed excellent performances in term of bone ingrowth, bone implant contact and push-out strength (Fig. 3).