**Core Concept**
Bone-implant integration is crucial for the long-term success of dental and orthopedic implants. Osseointegration is the process by which bone cells (osteoblasts and osteoclasts) form a direct structural and functional connection with the implant surface. Surface modifications can enhance this process by promoting cell attachment, proliferation, and differentiation.

**Why the Correct Answer is Right**
To achieve better osseointegration, implant surfaces are modified to increase their bioactivity and biocompatibility. Micro- and nano-texturing of the surface can enhance the mechanical interlocking of bone cells with the implant, while also promoting the deposition of bone minerals. This is achieved through techniques such as anodization, acid etching, or sandblasting, which create micro- or nano-scale features that mimic the natural bone matrix. These surface modifications can also increase the expression of osteogenic genes and proteins, such as alkaline phosphatase and bone morphogenetic protein-2 (BMP-2), which are essential for bone formation.

**Why Each Wrong Option is Incorrect**
**Option A:** Surface sterilization is important for implant hygiene, but it does not directly enhance osseointegration.
**Option B:** Implant size and shape can affect osseointegration, but surface modifications are more critical in this context.
**Option C:** Implant materials can influence osseointegration, but the correct answer focuses on surface modifications rather than material properties.

**Clinical Pearl / High-Yield Fact**
Remember that surface modifications can significantly impact the success of osseointegration. A well-designed surface can increase the implant's surface area by up to 50%, enhancing the mechanical interlocking and osseointegration process.

**Correct Answer:** C.