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Dental Studies
The role of magnets in the management of unerupted teeth in children and adolescents.
Cole BO, Shaw AJ, Hobson RS, Nunn JH, Welbury RR, Meechan JG, Jepson NJ.
Department of Child Dental Health, Department of Oral Surgery, and Department of Restorative Dentistry, Dental School & Hospital, Richardson Road, Newcastle upon Tyne, UK.
This case report describes the use of magnets in the management of teeth that fail to erupt. Eight children aged between 10 and 15 years were treated. Magnetic traction was applied to two premolars and six molars. Seven teeth (one premolar and six molars) erupted successfully (mean treatment time with magnetic traction: 7.5 months). One premolar failed to erupt; serial radiographic assessment over a 9-month period revealed no evidence of movement and so the magnetic fixture was removed. Histological evaluation of tissue samples taken from around the fixture revealed no evidence of abnormal pathology.
Int J Paediatr Dent 2003 May;13(3):204-7
Go to topPulsed electromagnetic fields promote bone formation around dental implants inserted into the femur of rabbits.
Matsumoto H, Ochi M, Abiko Y, Hirose Y, Kaku T, Sakaguchi K.
Department of Fixed Prosthodontics, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293 Japan.
The present study examined the effect of applying a pulsed electromagnetic field (PEMF) on bone formation around a rough-surfaced dental implant. A dental implant was inserted into the femur of Japanese white rabbits bilaterally. A PEMF with a pulse width of 25 microseconds and a pulse frequency of 100 Hz was applied. PEMF stimulation was applied for 4 h or 8 h per day, at a magnetic intensity of 0.2 mT, 0.3 mT or 0.8 mT. The animals were sacrificed 1, 2 or 4 weeks after implantation. After staining the resin sections with 2% basic fuchsin and 0.1% methylene blue, newly formed bone around the implant on tissue sections was evaluated by computer image analysis. The bone contact ratios of the PEMF-treated femurs were significantly larger than those of the control groups. Both the bone contact ratio and bone area ratio of the 0.2 mT- and 0.3 mT-treated femurs were significantly larger than the respective value of the 0.8 mT-treated femurs (P < 0.001). No significant difference in bone contact ratio or bone area ratio was observed whether PEMF was applied for 4 h/day or 8 h/day. Although a significantly greater amount of bone had formed around the implant of the 2-week treated femurs than the 1-week treated femurs, no significant difference was observed between the 2-week and 4-week treated femurs. These results suggest that PEMF stimulation may be useful for promoting bone formation around rough-surfaced dental implants. It is important to select the proper magnetic intensity, duration per day, and length of treatment.
Clin Oral Implants Res. 2000 Aug;11(4):354-60.
Go to topBiochemical study of human periodontal ligament: preparation of cell attachment materials induced by pulsed electromagnetic fields.
Kim KT.
Department of Oral Biochemistry, Kanagawa Dental College, Japan.
The periodontium, especially the periodontal ligament and alveolar bone, are tissues constantly subjected to physical stress such as occlusion and mastication. This study was designed to explore the effect of the pulsed electromagnetic fields (PEMF) on the cell attachment and the spread of human periodontal ligament fibroblasts (HPLF) and rat osteoblasts (ROB). PEMF are categorized as one type of mechanical stress. HPLF were obtained by the explantation method described by Saito et al. They were then subcultured in Dulbecco's modified Eagle's medium (D-MEM) and supplemented with 2 mg/ml dialyzed fetal calf serum protein (FCSP), 50 micrograms/ml ascorbic acid and penicillin/streptomycin after trypsinization. ROB were isolated from a two-day-old rat calvaria by the sequential bacterial collagenase digestion method described by Dziak and Brand and were subcultured in D-MEM supplemented with FCSP, ascorbic acid and penicillin/streptomycin. After the confluent HPLF were cultured with serum-free MCDB 107 medium, the quiescent HPLF were exposed with or without PEMF for 24 hr. This was followed by the collection of the control conditioned medium (C-CM) and PEMF exposed conditioned medium (PEMF-CM). The cell attachment assay was performed so that the hydrophobic 24 multiwells were coated with the whole conditioned medium or fractionated conditioned medium by a PO-60K column. After coating, heat inactivated BSA blocked nonspecific sites for cell adhesion, and 3H-TdR labeled HPLF or ROB were cultured on the precoated wells. The activity of cell attachment and spreading was determined by the radioactivity of 3H-TdR using a scintillation counter. The characters of cell attachment factors derived from HPLF were hydrophobic, heat labile and proteolytic enzyme digestible. In addition, the fractionated PEMF-CM enhanced the spreading activity of ROB. PEMF induced the 10 KDa which can enhance the HPLF and ROB spreading. Therefore, the cell attachment and spreading factors secreted by HPLF exposed with PEMF may regulate HPLF and also ROB.
Bull Kanagawa Dent Coll. 1990 Sep;18(2):89-98.
Effect of pulsed electromagnetic fields (PEMF) on human periodontal ligament in vitro. Alterations of intracellular Ca2+
Satake T, Yasu N, Kakai Y, Kawamura T, Sato T, Nakano T, Amino S, Ishiwata Y, Saito S.
Department of Oral Biochemistry, Kanagawa Dental College.
The concept of orthodontic tooth movement is based on the hypothesis that teeth move as a result of the biological response of periodontal tissues to the mechanical forces applied. There is a widely held hypothesis that mechanical stress generates an electrical signal which sets in motion the subsequent events, as in bone exposed to mechanical forces electrical currents are produced affect bone growth and remodeling. This implies a transduction mechanism which translates the electrical signal into a biochemical message, recognizable by the cellular machine. This study is aimed at the identification of the message and the investigation of its control. In fact, the effect of Pulsed Electromagnetic Fields (PEMF) on the intracellular second messenger, cytoplasmic Ca2+ in Human Periodontal Ligament Fibroblasts (HPLF) was investigated. The resting intracellular ionized calcium concentration ([Ca+2]i) of HPLF cells was 232.7 +/- 25.0 nM, and with PEMF [Ca2+]i increased from 12 hrs to 499.0 +/- 115.5 nM up to 12 hrs, then reached to a steady level through 24 hrs. The PEMF were also found to decrease the responses towards epidermal growth factor (EGF) and serum, when the degree of response was based on the intracellular Ca2+ transient. These effects of PEMF were mimicked by 12-0-tetradecanoyl phorbol 13-acetate (TPA), a potent activator of protein kinase C. Some reports have suggested that fibroblasts of the periodontal ligament contain high alkaline phosphatase (ALPase) activity as much as osteoblast. Since similar results concerning the [Ca2+]i were obtained in osteoblast (OB)-like cells, this experiment also supports the hypothesis that fibroblasts of periodontal ligament have osteoblastic features.
Kanagawa Shigaku. 1990 Mar;24(4):735-42.
Go to topThe use of a permanent magnetic field in the combined treatment of lichen ruber planus of the oral mucosa.
Kupriianova TA, Markov BP, Vilkova LA, Barabash AG.
In 51 patients, the conventional therapy was combined with application of plate prostheses with samarium-cobalt magnets. Clinical investigations showed a beneficial effect of the constant magnetic field on the inflammation relief, erosion epithelialization and papules disappearing from the oral cavity.
Stomatologiia (Mosk) 1989 Sep-Oct;68(5):33-4
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