Importance of Ca(2+) modifications for osseointegration of smooth and moderately rough anodized titanium implants - a removal torque and histological evaluation in rabbit.
BACKGROUND
Incorporation of Ca(2+) into the titania of anodized titanium surfaces has been found to enhance osseointegration. It provides a stable surface when the ions are incorporated into the oxide layer during the anodizing process. The Ca(2+) may suggestively be prominent sites for mineral induction, attract proteins, and catalyze intracellular cascades.


OBJECTIVE
The aim of the present study was to evaluate the osseointegration of smooth (S(a) < 0.5 µm) and moderately rough (S(a) 1.0-2.0 µm) commercially pure titanium implants, with and without Ca(2+) , in order to reflect on the importance of surface chemistry in relation to topography.


METHODS
Anodized implants with (OxCa) or without Ca(2+) (Ox), blasted implants (Bl), and blasted anodized implants, with (BlOxCa) or without Ca(2+) (BlOx), were inserted in rabbit femur and tibia. The implant surfaces were characterized using interferometry, scanning electron microscopy, and X-ray photoelectron spectroscopy prior to implant installation. Removal torque (RTQ) measurements were executed on all implants after a healing period of 12 weeks. The implants were, thereafter, removed en bloc with surrounding tissues and prepared for histological evaluations.


RESULTS
RTQ measurements of tibial implants revealed significantly higher values for BlOxCa implants (90.7 ± 23.3 Ncm) compared to OxCa (64.6 ± 18.2 Ncm) and BlOx implants (69.7 ± 17.5 Ncm) (p = 0.029). Ca(2+) modification of smooth implants placed in the femur did not reveal any differences.


CONCLUSIONS
Ca(2+) modification of smooth implants resulted in similar interfacial shear strength as moderately rough implants and Ca(2+) modification of moderately rough implants demonstrated the significantly strongest interfacial shear strength when placed in rabbit tibia. This possibly demonstrated surface chemistry compensating for lesser roughness.
Fröjd
Victoria
V
Department of Prosthodontics, Faculty of Odontology, Malmo University, Malmo, Sweden. victoria.frojd@biomaterials.gu.se
Wennerberg
Ann
A
Franke Stenport
Victoria
V
D000818:Animals; D002118:Calcium / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D020878:Device Removal; D005269:Femur; D008422:Materials Testing; D016348:Osseointegration; D010084:Oxidation-Reduction; D011817:Rabbits; D033081:Shear Strength; D013499:Surface Properties; D013977:Tibia; D014025:Titanium / Q000737:chemistry*; D019415:Torque
D020099:Coated Materials, Biocompatible; D015921:Dental Implants; C009495:titanium dioxide; D014025:Titanium; D002118:Calcium