A finite element model is used to explore the stress-strain responses of the mandibular central incisor and its associated periodontal ligament (PDL) while opening the bite. The finite element model consisted of the mandibular teeth, the alveolar bone, and the PDL of the mandibular incisors. The clinical scenario was simulated by applying a force of 10 cN to the mandibular incisor in a crown-root direction. The von Mises stress in the incisor and its PDL were calculated. Results: An obvious stress concentration at the tip and at the top of the alveolar ridge of the mandibular central incisors was found. In the PDL, tensile strain was recorded in one-third of the cervical and middle regions, whereas compressive stress occurred on one-third of the apex and both the distal and labial sides of the PDL. This illustrates the difficulty in achieving the desired intrusive movement along the long axis of the tooth in a clinical setting. The highest stress concentration in the PDL was located at the cervical margin and declined steadily to the apex. The maximum stress was 20.5GPa at the alveolar crest. This study indicated that finite element modeling is a feasible and effective method for studying the open-bite technique. Areas subjected to greater stress may develop cell hyalinization within the ligament.