What is the effect of steep incisal guidance on posterior disclusion during protrusion?

• A. It increases posterior contacts during protrusion.
• B. It has no effect on posterior contacts.
• C. It delays posterior disclusion.
• D. It tends to produce earlier posterior disclusion, reducing posterior contacts during protrusion.

Answer: (D)

Steep incisal guidance creates a sharp anterior guidance path during forward movement. When the mandible protrudes along this steep path, the incisors engage earlier and guide the movement in a way that separates the posterior teeth sooner. This results in posterior disclusion occurring earlier in the protrusive pathway, so there are fewer posterior contacts during protrusion. If incisal guidance were shallower, posterior contacts would tend to persist longer during protrusion.