What should be avoided when using coarse pumice?

Using coarse pumice on gold restorations should be avoided because this abrasive material can scratch and damage the surface of the gold, leading to a compromised finish and potential wear over time. Gold restorations require a gentle approach to maintain their polish and integrity, as they are softer than some other dental materials. Coarse pumice can create micro-abrasion that may lead to tarnishing or loss of the lustrous surface that is often desired in gold restorations.

In contrast, while there are considerations with the use of coarse pumice on healthy enamel and combining with fine grit, these do not present the same immediate risk of damage as using it directly on gold restorations. Maintaining the health of enamel is crucial, so using excessive abrasiveness could be counterproductive, but this is less critical than the direct harm it can cause to gold. Using pumice with water is a standard practice as it helps to control dust and improves the effectiveness of the polishing action.