A 27-year-old woman with bruxism suffered a spider bite (Loxosceles rufescens) on the left cheek that caused severe local cellulitis, facial palsy, and painful hyperesthesia over the two lower trigeminal nerve divisions. Facial but not trigeminal neuropathy improved, and she developed a labial dystonia that only corrected while pressing the right medial incisor. A specially designed maxillary splint that continuously pressed it suppressed both dystonia and related spontaneous firing of motor unit potentials in electromyography. Overstimulation of the contralateral trigeminal territory possibly compensated for the altered left trigeminal nerve input, balanced proprioceptive influences at the central inhibitory-excitatory circuitry, and controlled dystonia.