Effects Of Surface Microtopography Of Titanium Discs On The Gene Expression Of Osteotropic Cytokines IGF-I,TGF-β₁ In Osteoblasts

[Objective] To investigate the influence of different surface microtopography of titanium discs on the gene expression of osteotropic cytokines IGF-I and TGF- β₁ in osteoblasts.[Materials and Methods] The primary osteoblasts separated from calvarium of fetal rats were cultured and the third passage osteoblasts was seeded on 5 different surfaces of Ti discs - G (grooved), SB (sandblasted)1³, TPS (titanium plasma-sprayed) in 24-well plate. Different surface microtopography of the titanium discs and the osteoblasts' morphology on 5 types disc were observed by SEM. IGF-I mRNA was quantitated by real-time fluorescent quantitative-polymerase chain reaction and TGF-β₁, IGF-I content were measured by ELISA assay.[Results] (D Cell morphology : Osteoblasts adhered tightly to five different titanium surface; On G surface, osteoblasts were spindle-shaped along the groove; Osteoblasts were cubic, multangular and abundant cytoplasm on SB surface and TPS surface, spreading in all directions. (2) IGF-I mRNA expression: The level of IGF-I mRNA was increased from 1^st7th day on all discs; while it was significantly higher on SB and TPS surface than on G surface (P <0.05) . And the highest level was observed on SB3 surface, more than on TPS surface, which was significantly higher on 3, 5, 7 day (P<0.05) . There was no difference between TPS and SB2 surface(P >0.05) while it was significantly higher on TPS and SB2 than on SB1 surface on 1,5,7 day (P <0.05 ) .(3) IGF-I content measurement: There was no difference on all surface on the 1^st day(P >0.05), but an increase of IGF-I content was detected on SB3 surface than on other surfaces on 3 , 5, 7days (P<0.05) . There was no difference among TPS , SB2 and SB1 surface (P>0.05) while it was significantly higher onthese surfaces than on G surface on the 3rd day (P <0.05) ; On the 5th day, it was significantly higher on TPS and SB2 surfaces than on SBl and G surfaces while there was no difference between TPS and SB2 surfaces; it was significantly different on all surfaces except the TPS and SB2 surfaces on the 7th day. ?TGF-|3i content measurement: An increase of TGF-|3i production was detected on 3 type of SB and G surfaces with the increase of Ra. It was significantly higher on TPS and SB3 surfaces than other surfaces on the 1st day (P <0.05) ; and it was significantly lower on G and SBl surfaces than other surfaces on the 3rd day (P <0.05) ; On the 5th and 7th day, synthesis of TGF-Pi was more abundant on SB3 surface than other surfaces (P <0.05), and it was significantly higher on TPS and SB2 surface than on SBl and G surface (P <0.05) while there was no difference between TPS and SB2 surfaces.[ Conclusion ] The results indicate that rough surface could induce the differentiation and gene expression of TGF-P] and IGF-I in osteoblasts than smooth surface, sequently advantageous to bone formation around dental implant in vivo. In some extent, this effect is enhanced with the increase of roughness. In this study, the differentiation of osteoblasts is the best on the Ti discs with average roughness value 3.53^m, which was blasted with TiO2particles.