Which property of a luting agent can influence the retention of a dental restoration?

The property of a luting agent that influences the retention of a dental restoration is viscosity. Viscosity refers to the thickness or flow characteristics of a material. In the context of luting agents, a material with optimal viscosity ensures it can flow adequately into the microscopic details of the tooth structure and the restoration itself, creating a strong bond once it sets.

When the viscosity is appropriate, the luting agent can evenly coat the surfaces, maximizing surface area contact that is crucial for effective bonding. A high-viscosity agent may not flow well, failing to fill gaps, while a low-viscosity agent might dissipate too easily. Thus, a suitable viscosity is essential for ensuring retention by enhancing the mechanical interlocking and adhesive properties that secure the restoration in place.

The other factors listed do play roles in the overall function and performance of dental materials but do not directly influence retention in the same way. Color is typically a cosmetic consideration, tensile strength relates to the force that the material can withstand before failing, and thermal expansion affects how materials react to temperature changes, but these do not directly impact the immediate retention capability of the luting agent as viscosity does.