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. In other words, the posterior teeth have much larger crowns and more cusps than the anterior teeth.
The anterior teeth act as a buffer, enabling the posterior teeth to glide smoothly past one another during lateral or protrusive motions from their optimal position. The posterior teeth possess greater crowns and more cusps than the anterior teeth.