title: Effects of local injections of vasoactive drugs on eruption rate of incisor teeth in anaesthetized rats.
abstract: OBJECTIVE
  Previous studies have suggested that the vasculature in the dental pulp and periodontal tissues plays an important role in producing the eruptive force in continuously erupting incisors. The aim of the present study was to investigate the effects of local injections of vasoactive drugs on regional blood flow within the socket in association with axial tooth movements to clarify the role of the local vascular system on tooth eruption.
  
  
  METHODS
  Twenty-two male Wistar rats, weighing 309+/-21 g (S.D.), were immobilized with halothane anaesthesia. We measured the regional blood flow within the socket using a laser Doppler flowmeter, and the axial movements of the mandibular incisor using a displacement detector. The local injections of the vasoactive drugs, adrenaline (0.001, 0.01, and 0.1 microg/kg body weight) and acetylcholine (0.05, 0.5, and 5 microg/kg), into the base of the incisor were performed by a microinjector at a rate of 1 microl/kg body weight.
  
  
  RESULTS
  The injections of various doses of adrenaline decreased the mean regional blood flow and eruption rate dose-dependently, while those of acetylcholine increased the mean regional blood flow and eruption rate dose-dependently. The changes in the regional blood flow and eruption rate were transient. Significant correlations (p<0.001) were obtained between the maximum and minimum values in the regional blood flow and in the eruption rate following injections of various doses of adrenaline and acetylcholine.
  
  
  CONCLUSIONS
  These results support the hypothesis that the eruptive force of the rat incisor is closely related to the vasculature within the socket.
authors.affiliation: Department of Pharmacology, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Shimada
authors.forename: Koichiro
authors.initials: K
authors.lastname: Komatsu
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Chiba
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D007180:Incisor / Q000187:drug effects* / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects; D014078:Tooth Eruption / Q000187:drug effects* / Q000502:physiology; D014087:Tooth Movement Techniques; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000109:Acetylcholine; D004837:Epinephrine