치과용 순수 티타니움 임플란트의 표면 특성에 따른 뼈모세포의 초기 분화와 부착 = Early Differentiation and Attachment of Osteoblasts to Different Surface Roughness of Dental Pure Titanium Implant

국문 초록 (Abstract)

치과용 임플란트에서 뼈와 임플란트 표면 사이에 뼈 형성에 의한 긴밀한 초기 접촉이 성공적인 임플란트를 위하여 중요하다. 임플란트 주위에 뼈가 형성되는 과정에는 재료의 성질 외에 임플란트 자체의 표면 특성, 즉 표면거칠기 및 형태는 세포 반응에 영향을 미친다. 뼈모세포 또는 뼈모세포계열의 세포와 임플란트 표면과의 특이 반응은 궁극적으로 세포 표현형의 변화를 수반하게 된다. 본 연구는 뼈모세포주에서 서로 거칠기를 달리하는 순수 티타니움 임플란트 재료에서 세포 분화와 형태 변화를 세포증식법, 주사전자현미경 및 중합효소 반응을 이용하여 구명하고자 시도되었다.
배양접시의 polystylene well 표면과 매끈한표면 티타니움(smooth surface titanium)과 거친표면 티타니움(rough
surface titanium)의 표면거칠기 Ra 값은 각각 0.16±0.03 μm, 0.24±0.04 μm, 2.93±0.21 μm로 각 군간에 유의하
게 차이가 있었다. 배양 18시간과 5일 모두에서 거친표면 티타니움의 세포 수는 매끈한표면 티타니움에 비하여 유의하게 세포수가 적었다(p⁄0.01). 주사전자현미경적 소견에서 매끈한표면 티타니움의 세포는 방추형으로 거친표면 티타니움에 비하여 세포 경계가 매끈하고 티타니움 표면에 납작하게 부착되어 있었다. 거친표면 티타니움의 세포는 매끈한표면 티타니움에 비하여 세포경계가 비교적 거칠고 외형은 티타니움 표면의 돌출부와 함몰부 사이를 따라 굴곡을 보였으며, 세포 윤곽이 비교적 뚜렷하였다. 검사한 유전자 중 배양 18시간에서 erk2의 발현이, 배양 5일에서 erk1과 type I collagen 유전자의 발현이 거친표면 티타니움에서 증가되어 있었다(p⁄0.05).
이상의 결과는 매끈한표면 티타니움(Ra=0.24±0.04 μm)에 비교하여 거친표면 티타니움(Ra=2.93±0.21 μm)에서 세포는 증식보다는 분화를 보이며, 이 과정에 erk1과 erk2가 관여할 것으로 사료된다.

다국어 초록 (Multilingual Abstract)

Early bone formation and close contact between dental implant and tissue bed are important for successful osseointegrated dental implants. Surface characteristics of implant materials such as roughness and topography have effects on peri-implant tissue reaction in addition to chemical properties of dental implants. The
specific reactions of osteoblasts or their lineages to implant surface accompany changes of their phenotype. This study was undertaken to unravel cell differentiation and functional changes, responding to different implant surfaces characteristics. Cell proliferation, scanning electron microscopy and RT-PCR analyses for COX-2, ERK-1, ERK-2, Type I collagen, β-catenin, PLC-γ2, β-actin were carried using MG 63 preosteoblastic cells at 18 hours and 5 days of culture in vitro.
The number of attached cells on rough surface titanium (Ra=2.93±0.21 μm) was less than that on smooth surface
titanium (Ra=0.24±0.04 μm) at both 18 hours and 5 days of culture (p⁄0.01). Cells on smooth surface titanium were flat and spindle-shaped and their margin was smooth. In contrast, cells on rough surface titanium seemed to be thicker and shaped following pits and projections of the surface and their margin was irregular with many processes. At 18 hours of culture, erk2 mRNA expression in rough surface titanium was more than that in smooth. Similarly at 5 days of culture, erk1 and collagen I transcriptions were more than those of smooth surface titanium (p⁄0.01 and p⁄0.05 respectively).
These results suggest that rough surface titanium directs preosteoblasts toward differentiation rather than proliferation, comparing smooth surface titanium, and genes such as erk1 and erk2 would be involved in the cellular changes.

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