['To test the hypothesis that hypofunction/recovered occlusal function has no effect on the changes in insulin-like growth factor-1 (IGF-1) and IGF-1 receptor expressions and cell proliferation of periodontal ligament (PDL) cells.', "To produce occlusal hypofunction, the appliances were attached to the rats' maxillary and mandibular incisors. Subsequently, occlusal contact of the molar area was thoroughly recovered by removal of the appliances.", 'In periodontal sections, localization of IGF-1, the IGF-1 receptor, and proliferating cell nuclear antigen (PCNA) immunoreactive cells was significantly more expressed in the control group compared with the hypofunctional group (P < .01). In addition, after the recovery of the occlusion, IGF-1, IGF-1 receptor, and PCNA were detected significantly much more than in the hypofunction group (P < .01).'] Do occlusal stimuli influence on the expression of IGF-1 and the IGF-1 receptor in the rat periodontal ligament?