Osteogenecity of octacalcium phosphate coatings applied on porous metal implants

Abstract

The biomimetic route allows the homogeneous deposition of calcium phosphate (Ca-P) coatings on porous implants by immersion in simulated physiologic solution. In addition, various Ca-P phases, such as octacalcium phosphate (OCP) or bone-like carbonated apatite (BCA), which are stable only at low temperatures, can be deposited. In this pilot study, experiments were designed with a twofold-purpose: (1) to investigate the osteoinduction of OCP-coated and noncoated porous tantalum cylinders and of dense titanium alloy cylinders (5 mm in diameter and 10 mm in length) in the back muscle of goats at 12 and 24 weeks (n = 4); and (2) to compare the osteogenic potentials of BCA-coated, OCP-coated, and bare porous tantalum cylinders in a gap of 1 mm created in the femoral condyle of a goat at 12 weeks (n = 2). In the goat muscle, after 12 weeks the OCP-coated porous cylinder had induced ectopic bone as well as bone within the cavity of the OCP-coated dense titanium cylinder. In the femoral condyle, bone did not fill the gap in any of the porous implants. In contrast with the two other groups, OCP-coated porous cylinders exhibited bone formation in the center of the implant. The nature of the Ca-P coating, via its microstructure, its dissolution rate, and its specific interactions with body fluids, may influence the osteogenecity of the Ca-P biomaterial.

The rational use of animal models in the evaluation of novel bone regenerative therapies

“…Biomaterials have a range of properties, from osteoinductive and osteoconductive to immunomodulatory. Hydroxyapatite and calcium phosphate as well as their composites such as HA/poly(DL-lactic-co-glycolic acid) (PLGA), in the form of ceramics, cements and coatings have shown osteoinduction in animal models [60][61][62][63][64][65][66]. Various hybrid materials combined as co-polymers, polymer blends and polymer-ceramic blends have also shown efficacy [67][68][69][70][71][72][73].…”

Relevance of Osteoinductive Biomaterials in Critical‐Sized Orthotopic Defect

“…Osteoinduction has been shown in soft tissues of various animal models by a number of calcium-phosphate (CaP) containing bulk ceramics such as hydroxyapatite (HA), 2-9 a-tricalcium phosphate (a-TCP), b-TCP-, BCP, a-pyrophosphate, and b-pyrophosphate. 2,3,6,10 -18 Furthermore, ectopic bone formation has been observed by octacalcium phosphate (OCP)-coated porous biomaterials, 12,13,19 CaP cements, 11,20 and glass ceramics. 21 Osteoinduction has also been reported by porous alumina ceramic 22 and titanium.…”

Dry And Ringer Solution Lubricated Tribology Of Thin Osseoconductive Metal Oxides And Diamond-Like Carbon Films

“…The substrates were cleaned before film deposition in an industrial washing machine with tenside surfactant based washing agents in order to remove contaminations from the surface. Afterwards, they were mounted in the vacuum chamber (Leybold Univex 450, Leybold Vacuum, Cologne, Germany) under laminar flow conditions (comparable to clean room class 3 (DIN ISO EN 14644-1) with <1000 particles of 0.1 μm diameter per m 3 ) to prevent dust contamination on the substrate surfaces. After evacuating to 4×10 -3 Pa, the pretreatment for removing oxide layers on the silicon substrates was performed with the neutralized plasma of an anode layer ion source (ALS 340, Veeco, Fort Collins, CO, USA) [12].…”

“…Barradas et al stated in their review paper, that bone morphogenetic proteins are surely involved in osteoinduction, but the ability of a material to form a biological apatite layer on its sur- face either by dissolution / reprecipitation or by nucleation from biological fluids, is mandatory too [1]. An overview on different implant materials shows quite low osteoinductive tendency for pure metals like titanium, zirconium and tantalum as well as for widely used titanium alloys (TiAl6V4) [2][3][4][5], while chemical treatments to achieve thick oxide films, the deposition of calcium phosphate (hydroxyapatite, tricalcium phosphate, calcium phosphate, etc.) and alumina films on titanium surfaces improve bone formation and mineralization of subsequently formed extracellular matrix [1,6,7].…”