Chemical reactions
The process is a combination of electrochemical reaction,
acid-base reaction and precipitation reaction. 1. Water is reduced
at the cathode (implant surface) 2 H2O + 2e- = H2 + 2 OH2. The
hydroxide ions react with dihydrogen phosphate according OH- +
H2PO4 H2O + HPO4 2-
3. Then follows the precipitation of calcium phosphates Ca2+ +
H2PO42- + 2 H2O CaHPO4 x 2 H2O
5 CaHPO4 x 2 H2O + 6 OH- Ca5(PO4)3OH + 2 PO4 3- + 15 H2O The
result is a composite of 2 calcium phosphate phases: Hydroxyapatite
(HA) and Brushite, a physiological precursor of HA [1, 2, 3, 4,
5].
Post treatment
Heating by a temperature of max. 130C for 20 minutes.
Sterilization gamma sterilization process
B. Chemical and Crystallographic Analysis of the BONIT
coating
Test
Method
Results
Element Analysis
Atomic Absorption (ASTM F 1185)
Heavy metals (ASTM F 1185-88)Arsenic(DIN EN ISO 11969-D18)
0.08 ppm 9.6 ppm
Lead(EN ISO 11885-E22)
Cadmium(EN ISO 11885-E22)
