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)