Effect of surface grain boundary density on preosteoblast proliferation on titanium

Terry C Lowe,Rebecca A Reiss,Patrick E Illescas,Casey F Davis,Melanie C Connick,Johnny A Sena

doi:10.1080/21663831.2020.1744758

Abstract

ABSTRACTStudies since 2004 have shown that the cytocompatibility of ultrafine grain (UG) commercial purity (CP) titanium exceeds that of coarse grain (CG) CP titanium (Ti) by 30% to 20-fold. To isolate the factors affecting this large reported variability of CP titanium’s cytocompatibility, discs of UG and CG titanium were fabricated with controlled texture and roughness. The discs were seeded with MC3T3-E1 pre-osteoblastic cells and cultured for 72 h. The proliferation of cells on polished UG-Ti exceeded unpolished CG-Ti 3.04-fold. Cell proliferation was found to correlate with a new biophysical parameter, the average grain boundary length per surface-attached cell.

Highlights

Titanium (Ti) alloys are widely used for dental implants [1] and orthopaedic devices [2]
Preosteoblasts from the MT3T3-E1 line were cultured for 72 h on four states of commercial purity (CP) Ti substrates: coarse grain (CG) and ultrafine grain (UG), and with or without polishing to nanometric smoothness
The combination of having ultrafine grains and nanosmooth surfaces produced the greatest increase in the number of surface-attached cells, by a factor of 3.04 compared to unpolished CG-Ti

Summary

Introduction

Titanium (Ti) alloys are widely used for dental implants [1] and orthopaedic devices [2]. The design of microstructures and surfaces of Ti medical implants has been the focus of research to enhance the integration of Ti with bone tissue [3]. The strength [5], corrosion resistance [6], and cytocompatibility [7,8] of commercial purity (CP) Ti can be enhanced by introducing sub-micron and nanometer-scale microstructural features via Severe Plastic Deformation (SPD) methods to produce ultrafine grain (UG) titanium. Continuous Equal Channel Angular Pressing (C-ECAP) [9], a specific form of SPD, can fabricate long, high-strength Ti rods suitable for making medical devices [10]. C-ECAP reduces grain size, alters grain boundary structure, and increases the areal surface density of grain boundaries [11]

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