At rest, consciously maintain a space of 2 to 4 mm between your upper and lower teeth in order to relax the jaw muscles, relieve the joints, and prevent enamel wear.

noli's read

The existence of a relaxation gap between the teeth, commonly known as the 'freeway space,' is the subject of a strong historical consensus in research on oral posture. Reference textbooks on dental balance, which synthesize decades of clinical observations and expert opinions, confirm that a gap of 2 to 4 mm characterizes the ideal resting position. At this distance, the masticatory muscles reach their minimal tension level, which avoids fatigue and preserves the joint from unnecessary pressure. Constant contact or unconscious clenching prevents this essential muscle recovery, which can generate tension and wear down enamel prematurely. While the idea of a '5-second test' is an excellent tool for rapid awareness (or biofeedback) for the general public, the exact measurement of this space is instead based on pronunciation or swallowing exercises in a clinical setting. This advice regarding alignment and relaxation is therefore scientifically sound and constitutes an excellent daily wellness reflex.

the sources

No named source held this one up — that absence is part of the verdict.