In dentistry, a mutually protected occlusion is an occlusal scheme in which the anterior teeth protect the posterior teeth, and vice versa.
The anterior teeth protect the posterior teeth by providing for a plane of guidance during excursions, thus allowing the cusps of the posterior teeth to disclude rather than strike one another during lateral or protrusive movements from centric relation.
Because posterior crowns are wider and possess cuspal projections in various configurations, the cusps of the maxillary teeth and those of the mandibular teeth have an opportunity to bang into each other during chewing, speech or simply meeting together when one bites down.
This requires less force because the anterior teeth are further from the joint (analogous to stopping a door further from its hinge).
While anterior teeth may retain their natural position even after loss of posterior teeth, the masticatory forces will eventually cause the single-rooted anterior to splay, thus leading to a collapsed bite.