This pilot study describes responses of Sprague Dawley rats to mandibular retrusion. Lingually overcontoured crowns were cemented onto maxillary incisors to produce 3.5 mm of autoretrusion. Monitoring data indicate that activity was suppressed and nutritional intake was reduced. Histologic evaluation of the 2-, 4-, 7-, and 59 day test specimens detected only a monocytic infiltrate response in the 4-day group.