Redefining microrough titanium surfaces: Thermo-engineered soft-edge microrough surfaces resolve the
Toshikatsu Suzumura1, Rune Shibata1, Gauri Vanjari1
1Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, CA, United States.
Objectives:
Microrough titanium surfaces, the clinical gold standard for osseointegration, accelerate osteoblast differentiation but suppress proliferation, limiting bone volume and imposing a biological ceiling on bone-implant contact. This study aimed to resolve this long-standing trade-off by targeting microtopographic peak sharpness, hypothesizing that sharp knife-edge features suppress osteoblast proliferation.
Methods:
Commercially pure titanium disks were acid-etched to create microrough surfaces, then thermally contoured to selectively round micropeaks while preserving roughness amplitude and spatial patterning. Surfaces were comprehensively characterized for their morphology, chemistry, and physicochemistry. Osteoblast attachment, spreading, proliferation, differentiation, and intracellular redox balance were assessed. In vivo osseointegration was evaluated in rat femurs by push-in biomechanical testing.
Results:
Soft-edge microrough surfaces restored osteoblast attachment and proliferation to levels comparable with smooth titanium, while maintaining osteogenic differentiation marker expression. Mechanistically, they alleviated oxidative stress and enhanced glutathione-based redox buffering capacity. In vivo, implants with soft-edge surfaces demonstrated a 2.5-fold increase in osseointegration energy and significantly greater bone coverage without altering bone mineral quality. By integrating rarely applied roughness parameters (Sku, Spc, Spd, Sk, Vvc) with conventional metrics, we achieved a multidimensional characterization that precisely distinguished the novel soft-edge geometry from traditional knife-edge microtextures, directly linking peak sharpness to biological performance.
Significance:
This work identifies peak sharpness as a critical determinant of osteoblast kinetics and introduces a simple, cost-effective, and scalable thermo-engineering strategy that resolves the classical proliferation-differentiation dichotomy. The creation of a biologically intelligent soft-edge microrough surface represents a conceptual and technological breakthrough, redefining surface design for next-generation biomaterials.
