Oregon Expanded Function Dental Assistant (EFDA) Practice Exam

When material oozes through the holes of a perforated tray, it creates mechanical locks. This phenomenon occurs because the material, often a dental impression material or a similar substance, flows into the small openings of the tray and then hardens. As it sets, the undulating surface of the material interlocks with the edges of the tray holes, forming a physical connection that securely holds the impression material in place.

Mechanical locking is important in dental procedures because it ensures that the material will not shift during the setting process, which is crucial for obtaining accurate impressions. This interlocking setup contributes to the overall stability and effectiveness of the impression.

The other options do not accurately describe the interaction between the material and the tray. Chemical bonds would imply a molecular interaction that is not relevant here, adhesive connections would suggest a different type of chemical adhesion rather than a physical interlock, and surface tensions refer to the cohesive forces at the surface of the material rather than the locking mechanism itself. Thus, the correct answer highlights the significance of the mechanical lock in this context.