The best material for the tissue side of a pontic is ceramic because it offers optimal biocompatibility and tissue compatibility, minimizing irritation and inflammation of the underlying mucosa. Ceramic's smooth, glazed surface resists plaque accumulation and facilitates easier cleaning, which is critical for maintaining periodontal health. Additionally, ceramic provides superior esthetics and durability compared to acrylic resin or composite materials. Metals can cause tissue discoloration and are less favorable for the tissue-contacting surface. Therefore, ceramic ensures both functional and esthetic success of pontics in fixed prosthodontics.

Reference: Principles of Fixed Prosthodontics, Shillinburg, 4th Edition.