Effect of a static magnetic field on orthodontic tooth movement in the rat.
Orthodontic tooth movement may be enhanced by the application of a magnetic field. Bone remodelling necessary for orthodontic tooth movement involves clastic cells, which are tartrate-resistant acid phosphatase (TRAP) positive and which may also be regulated by growth hormone (GH) via its receptor (GHR). The aim of this study was to determine the effect of a static magnetic field (SMF) on orthodontic tooth movement in the rat. Thirty-two male Wistar rats, 9 weeks old, were fitted with an orthodontic appliance directing a mesial force of 30 g on the left maxillary first molar. The appliance incorporated a weight (NM) or a magnet (M). The animals were killed at 1, 3, 7, or 14 days post-appliance insertion, and the maxillae processed to paraffin. Sagittal sections of the first molar were stained with haematoxylin and eosin (H&E), for TRAP activity or immunohistochemically for GHR. The percentage body weight loss/gain, magnetic flux density, tooth movement, width of the periodontal ligament (PDL), length of root resorption lacunae, and hyalinized zone were measured. TRAP and GHR-positive cells along the alveolar bone, root surface, and in the PDL space were counted. The incorporation of a SMF (100-170 Gauss) into an orthodontic appliance did not enhance tooth movement, nor greatly alter the histological appearance of the PDL during tooth movement. However significantly greater root resorption (P = 0.016), increased width of the PDL (P = 0.017) and greater TRAP activity (P = 0.001) were observed for group M at day 7 on the compression side. At day 14 no differences were observed between the appliance groups.
Tengku
B S
BS
School of Dentistry, University of Queensland, Australia.
Joseph
B K
BK
Harbrow
D
D
Taverne
A A
AA
Symons
A L
AL
D000135:Acid Phosphatase / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D016723:Bone Remodeling; D002452:Cell Count; D007124:Immunoenzyme Techniques; D007527:Isoenzymes / Q000378:metabolism; D008280:Magnetics; D008297:Male; D008437:Maxilla; D008963:Molar; D009967:Orthodontic Appliances; D010513:Periodontal Ligament / Q000166:cytology; D010519:Periodontium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011986:Receptors, Somatotropin / Q000378:metabolism; D012391:Root Resorption / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D014092:Tooth Root / Q000378:metabolism
D007527:Isoenzymes; D011986:Receptors, Somatotropin; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase