A touch-guided neural circuit regulates motivated gnawing to maintain dental alignment

How hindbrain circuits integrate peripheral and central signals to regulate complex oral behaviors is poorly understood. In rodents, gnawing is essential for localized tooth wear to offset lifelong incisor growth. Whether this process relies on specific sensory input to guide localized tooth wear and is actively regulated by neural mechanisms remains unresolved. Here, we identify somatostatin-expressing neurons in the spinal trigeminal nucleus oralis as a central relay distributing tactile input to motor execution and motivational circuits. These neurons receive input from a genetically distinct population of S100b⁺ Aβ low-threshold mechanoreceptors that innervate the incisor periodontium and project to both jaw-closing motor neurons and, via the parabrachial nucleus, the ventral tegmental area. Disruption of this pathway abolished gnawing and resulted in severe malocclusion, while activation triggered dopamine release in the nucleus accumbens. Our findings redefine dental alignment as an active, touch-dependent, circuit-governed process and reframe malocclusion as a sensorimotor-motivational integration disorder.