TABLE 1.

Characteristics of the surface modification techniques for microtopography.

Types	Techniques	Process	Advantages	Limitations
Uncontrolled Microtopography	Plasma Spraying	Thermal spraying technique; Vacuum deposition	Easy to operate; High bonding strength; Economical	Leakage of ions; Difficult to coat inner surface of small holes
	Grit Blasting	Forcing abrasive particles against the implant surface	Simple and low-cost; Roughen the surface	Low processing efficiency; Blasting material residue
	Chemical Etching	Removing materials and fabricating roughness	Low-cost; Leaf-like, needle-like or pyramid-like nanostructures can be obtained	Depending on acid concentration, temperature, and time
	Anodic Oxidation	An accelerated electrochemical process	Simple process; High hardness; Nanometer features; High stability; Enhancing the corrosion resisitance	High energy consumption; Bonding strength with matrix needs to be further improved
Controlled Micro- topography	Laser Treatment	A physical technique of high density form	Able to fabricate complex and high resolution topography; Rapid and clean; Good repeatability	Optimization of all parameters is a big challenge; Multiple treatment sessions and limited
	Photo-lithography	Selectively dissolving photosensitive polymer and leaving latent on substrate	Ideal for microsturcture	Usually requires flat surface and needs chemical post-treatment
	Hot Embossing	Form a relief pattern at an elevated temperature by pressing master into the polymer	Cost-effcctive; Precise; Rapid, and mass production	Restricted to thermoplastics and difficult to fabricate comlex 3D micro- structures
	Micro-milling	Material-removal process using microscale milling tools	Simple; Without affecting the key characteristics of implant surface	Slow and inefficient; Restricted by the available smallest diameter of milling cutters