Australian Dental Council (ADC) Practice Test 2026 - Free ADC Practice Questions and Study Guide

The correct choice highlights the critical importance of maintaining the integrity of porcelain during the manufacturing process, specifically between the heat treatment stage and the opaque/bake stages. During heat treatment, the porcelain undergoes a process that strengthens its structure and prepares it for subsequent applications. If any contamination occurs at this stage, it can negatively affect the chemical bond in the opaque layer, which is crucial for both aesthetic and functional purposes.

The opaque layer is used to mask the underlying framework and can only bond effectively if the surface remains uncontaminated. The presence of contaminants, such as oils, dust, or impurities, can inhibit proper adhesion and compromise the strength and stability of the final product. Therefore, ensuring cleanliness between these stages is vital to achieving a durable and successful porcelain restoration.

In contrast, the other stages mentioned in the question do not pose the same level of risk concerning the chemical bonds formed. For example, while there are considerations at different stages, the implications of contamination are most critical when applying the opaque layer after heat treatment.