Introduction: Remodeling of tissues frequently occurs in the periodontal ligament during orthodontic tooth movement, including various changes in the vascular system. Although studies have investigated lymphatic vessels in the periodontal tissues, only a few studies have observed lymphatic vessels in the periodontal ligament, leaving many unclear aspects.
Materials and Methods : Using mice (PN-0, 7 and 14 days old) with unerupted mandibular first molars, lymphatic distribution and the existence of lymphatic vessels in the periodontal tissues including the periodontal ligament were immunohistochemically (LYVE-1) observed.
Results: Lymphatic vessels were observed beneath the oral epithelium, beneath the epithelium of the attached gingiva and inside the mandibular canal. Some lymphatic vessels beneath the epithelium of the attached gingiva were present along the alveolus. Although LYVE-1 positive structures distributed irregularly at each age in the areas of periodontal ligament at the future sites of crown formation, root formation and root apical region of root formation, no lymphatic vessels were identified.
Discussion: In the periodontal ligament of adult mice, it was supposed that lymphatic vessels in the periodontal ligament except the apex of root were not distributed from initial stage, and lymphatic vessels were observed near the apex in adult mice was distributed during the apex of root completion stage. This might be connected to the presence of the Hertwig's epithelial sheath.