Interfacial gene expression and stability of oxidized and machined titanium implants

• In previous studies, combination of experimental model and gene expression analysis showed that from 3 hours to 6 days of implantation, significant differences in expression of genes denoting for cellular recruitment, inflammation, bone formation and bone resorption were seen at the interfaces of screw-shaped oxidized and machined titanium implants. It was concluded that the modulation of gene expression in favor of osteogenic differentiation and downregulation of the pro-inflammatory responses might explain the improved osseointegration of the oxidized implant surfaces. However, as a major condition, the developed bone-implant interface needs to be mechanically stable in order to fulfill the requirements of osseointegration The aim of the current study was to combine in vivo interfacial gene expression model with torque analysis in order to determine how molecular and cellular events taking place at the different titanium implants are related to the biomechanical properties of the interface. Anodically oxidized and machined titanium miniscrews were inserted in tibiae of 6 rats. Each rat received two oxidized implants in one tibia and two machined implants in the opposite tibia. After 28 days, the implants were removed using torque measuring equipment. The torque was registered and the implants completely removed and analyzed with quantitative polymerase chain reaction (n=12). Wilcoxon signed rank test was used to analyze the statistical differences of biomechanical and gene expression results between the two implant types. In addition, similar oxidized and machined titanium miniscrews were characterized topographically, chemically and ultrastructurally using profilometry, Auger electron microscopy and cross-sectioning electron microscopy, respectively. For chemical and topographical analyses, 3 implants from each type were analyzed. The measurements were made on flanks, tops, and valleys of two nonadjacent threads giving a total of 18 measurements for each implant type. Topographical comparisons were performed using one-way ANOVA followed by Bonferroni’s test. The biomechanical evaluation demonstrated 190% increase in torque values for the oxidized implants as compared to the machined ones. At the same time (28d), oxidized implants showed significantly higher expression of Runt-related transcription factor 1, osteocalcin, and tartrate resistant acid phosphatase. On the other hand higher expression of tumor necrosis factor-α and interleukin-1β was detected on the machined surfaces. Surface characterization procedures revealed major differences in the physico-chemical properties of the implant surfaces. In conclusion, the favorable cellular and molecular events at the oxidized implants were in parallel with significantly stronger bone anchorage during osseointegration

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Biomaterialvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Biomaterials Science (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

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