title: Effects of a low level laser on periodontal tissue in hypofunctional teeth.
abstract: Malocclusions, such as an open bite and high canines, are often encountered in orthodontic practice. Teeth without occlusal stimuli are known as hypofunctional teeth, and numerous atrophic changes have been reported in the periodontal tissue, including reductions in blood vessels in the periodontal ligament (PDL), heavy root resorption, and reduced bone mineral density (BMD) in the alveolar bone. Low Level Laser (LLL) has been shown to have a positive effect on bone formation and the vasculature. Although the recovery of hypofunctional teeth remains unclear, LLL is expected to have a positive influence on periodontal tissue in occlusal hypofunction. The aim of the present study was to elucidate the relationship between LLL and periodontal tissue in occlusal hypofunction. Twenty-four male rats aged 5 weeks were randomly divided into control and hypofunctional groups. An anterior metal cap and bite plate were attached to the maxillary and mandibular incisors in the hypofunctional group to simulate occlusal hypofunction in the molars. LLL irradiation was applied to the maxillary first molar through the gingival sulcus in half of the rats. Rats were divided into four groups; control, control+LLL, hypofunctional, and hypofunctional+LLL. Exposure to LLL irradiation was performed for 3 minutes every other day for 2 weeks. Animals were examined by Micro-CT at 5 and 7 weeks and were subsequently sacrificed. Heads were resected and examined histologically and immunohistologically. The hypofunctional group had obvious stricture of the PDL. However, no significant differences were observed in the PDL and alveolar bone between the hypofunctional+LLL and the control groups. In addition, the expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF)-positive cells were higher in the hypofunctional + LLL group than in the hypofunctional group. These results indicated that LLL enhanced the production of bFGF and VEGF in the periodontal tissue of hypofunctional teeth.
authors.affiliation: Hiroshima Shuccho Dental clinic, Hiroshima, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Hayashi
authors.affiliation: Postgraduate Student, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Science, Hiroshima, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Terao
authors.affiliation: Assistant Professor, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Science, Hiroshima, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kunimatsu
authors.affiliation: Char and chief professor, Department of Orthodontics, Kanagawa Dental University, Kanagawa, Japan.
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Kawata
mesh_terms: D000818:Animals; D015519:Bone Density; D003766:Dental Occlusion; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D028022:Low-Level Light Therapy; D008297:Male; D008310:Malocclusion / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D008437:Maxilla / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D010513:Periodontal Ligament / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D010519:Periodontium / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D014070:Tooth / Q000473:pathology / Q000528:radiation effects*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D055114:X-Ray Microtomography
chemical_list: D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2