Resin is the preferred material for dental inlays because it offers excellent esthetic qualities, allowing for color matching with natural teeth, which is crucial for visible restorations. It also bonds well to tooth structure, providing good adhesion and minimizing microleakage. Resin inlays can be easily fabricated and adjusted chairside or in the lab, and they exhibit adequate strength for moderate occlusal stress. Unlike amalgam, resin avoids concerns about amalgam toxicity and metal color, and unlike gold, it is more conservative and patient-friendly in appearance. Porcelain is also used but requires more complex fabrication and can be more brittle. Thus, resin balances functionality, esthetics, and ease of use effectively.

Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.