What is the effect of using a hard night guard on joint loading?

• A. Increase loading by 85%
• B. Decrease loading by 25%
• C. Decrease loading by 85%
• D. No change in loading

Answer: (C)

Using a hard night guard creates a stable, flat occlusal surface that distributes forces and guides the jaw into a more relaxed position. This design intercepts and spreads the bite forces across the splint, reducing the amount of force transmitted directly to the TMJs during clenching or grinding. With the guard in place, muscle activity can lessen and the condyles experience less direct load, leading to a substantial reduction in joint loading. In the context of this question, that reduction is described as about 85%, reflecting the large decrease achieved with a well-made hard stabilization splint.