Changes in response properties of periodontal mechanoreceptors during tooth movement in rats.
Using an in vitro model, we investigated the chronological effects of orthodontic force on the response properties of periodontal mechanoreceptors (PMRs) in the rat mandibular first molar (M1). Experimental tooth movement was obtained by attaching a super-elastic titanium-nickel (Ti-Ni) alloy closed coil spring from the mandibular incisors to the right M1. On 1, 2, 3, 4, 7 and 14 days after the appliances were set, three right mandibular molars were extracted and direct stimulation with von Frey hairs was applied to the PMRs remaining in the tooth sockets of right M1. Single unit discharges were recorded from the inferior alveolar nerve. Following results were obtained; (1) in the 1-, 2- and 3-day groups, the mechanical thresholds were significantly lower than those in the control group. In the 4-day group, the mechanical threshold was significantly higher than that of the 3-day group. (2) In the 3-, 4-, 7- and 14-day groups, the conduction velocities of A(beta) units were lower than those in the control group. These results imply that orthodontic force applied to M1 induced functional changes in the PMRs within a few days, suggesting that the PMR seems to respond to orthodontic force at early stage of tooth movement.
Ogawa
Taichi
T
Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan. gto.orts@tmd.ac.jp
Ishii
Noribumi
N
Toda
Kazuo
K
Soma
Kunimichi
K
D000704:Analysis of Variance; D000818:Animals; D003722:Dental Alloys; D004558:Electric Stimulation; D005260:Female; D008340:Mandibular Nerve / Q000502:physiology; D008465:Mechanoreceptors / Q000502:physiology*; D023421:Models, Animal; D008963:Molar / Q000294:innervation; D009431:Neural Conduction / Q000502:physiology; D009532:Nickel; D009969:Orthodontic Wires; D010513:Periodontal Ligament / Q000294:innervation*; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium; D014087:Tooth Movement Techniques; D020390:Tooth Socket / Q000294:innervation; D014110:Touch / Q000502:physiology
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium