Which type of rubber cup is more resilient and does not stain teeth?

The correct choice is synthetic cups. Synthetic rubber cups are designed to be more resilient and offer advantages in dental applications, particularly in terms of durability and functionality. They are manufactured from materials that do not easily stain teeth, which is important for maintaining the aesthetic appearance of a patient's smile after procedures like polishing.

Natural rubber cups, while they may have certain desirable properties, can absorb pigments and cause staining, which is a downside when compared to synthetic options. The resilience of synthetic cups allows them to withstand the stresses of dental procedures without breaking down or losing their effectiveness over time, enhancing their performance during tooth polishing.

Hard and soft cups refer to the texture and firmness of the cup rather than its staining properties. Hard cups can provide a strong polishing action, but they are not necessarily more or less likely to stain than their soft counterparts. Soft cups, while gentle and less likely to cause abrasions on tooth surfaces, do not inherently provide the same durability or stain-free benefits as synthetic options. Thus, when considering resilience and stain resistance, synthetic cups emerge as the most suitable choice.