Biomedical subjects

Mototsugu Chiba

Publications and source records attributed to Mototsugu Chiba.

5 recordsLinked to original sources

PubMed2006

Effects of an intravenous infusion of Ringer's solution on eruption rates of incisor teeth in anesthetized rats.

OBJECTIVE: The vasculature within the socket is reportedly involved in determining the position of continuously erupting teeth. Thus, loss of body fluid in anesthetized rats, which would affect the vascular physiology, should influence tooth movement. We investigated the effects of an infusion of Ringer's solution on the systemic arterial blood pressure, regional blood flow at the base of the incisor, and axial tooth movement in anesthetized rats to determine the cause of tooth displacement. MATERIAL AND METHODS: In the experimental group, the animals received intravenous infusions of Ringer's solution at 27 microl/min for 13 h. In the control group, the animals did not receive the infusion. RESULTS: The infusion of Ringer's solution suppressed an increase of the mean arterial blood pressure from 86 to 80 mmHg and a decrease of the regional blood flow from 170 to 217 mV, and increased the eruption rate from 267 to 361 microm/13 h during the experimental period. There was a positive correlation between the eruption rate and regional blood flow, and a negative correlation between the blood pressure and regional blood flow. CONCLUSIONS: These results suggest that an infusion of Ringer's solution can cause an increase in the regional blood flow, resulting in increased fluid volume, elevated intra-socket pressure, and increased eruptive movement. It is possible that the regional vascular volume and/or pressure within the socket play an important role in determining the position of the incisor.

Animals↗

PubMed2005

Effects of local injections of vasoactive drugs on eruption rate of incisor teeth in anaesthetized rats.

OBJECTIVES: 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. DESIGN: 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. CONCLUSION: These results support the hypothesis that the eruptive force of the rat incisor is closely related to the vasculature within the socket.

Acetylcholine↗

PubMed2003

Restoration of mechanical strength and morphological features of the periodontal ligament following orthodontic retention in the rat mandibular first molar.

Biomechanical properties and morphological features of the periodontal ligament (PDL) in the rat mandibular molars were examined during orthodontic retention. Seventy-three male rats of the Wistar strain, 8 weeks of age, were used for biomechanical analysis and six rats for morphological analysis. An elastic band was inserted between the mandibular first and second molars for 4 days; after removal of the elastic band the interdental space was filled with resin for 4 and 8 days. The maximum shear stress, tangent modulus, and failure strain energy density of the PDL of the first molar in the experimental animals decreased markedly following application of an orthodontic force. They increased rapidly and were restored completely to the control levels by the 8th day after retention. Light microscopy showed severe compression and extension of the PDL in the experimental animals on the 8th day after retention. Birefringent collagen fibre bundles running across the compressed and expanded PDL were observed, although they appeared to be thinner with less insertions into the alveolar bone or cementum in the experimental animals than in the controls. This suggests that the periodontal collagen fibres were partially reorganized and rearranged during retention. The reorganization and rearrangement of periodontal collagen fibres seemed to be partly related to the restoration of mechanical strength of the rat molar PDL during the 8 days of retention.

Alveolar Process↗

PubMed2003

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Journal Article↗

PubMed2002

Polarized light microscopic analyses of collagen fibers in the rat incisor periodontal ligament in relation to areas, regions, and ages.

We prepared decalcified sagittal sections (20 microm thick) from the incisal, middle, and basal regions of the mandibular incisor of male Wistar rats aged 2, 6, 12, and 24 months, and examined the sections using polarized light microscopy. Most of the birefringent fibers appeared to run obliquely across the periodontal ligament. Birefringent fibers running parallel to the long axis of the incisor were also found in the intermediate area of the ligament. Similar fiber architecture was observed in all four age groups. Quantitative analysis showed that the retardation values of collagen were higher in the bone- and tooth-related areas and lower in the intermediate area of the ligament. The values for the bone- and tooth-related areas increased from the basal toward the incisal regions in all four age groups. Age-related changes in the retardation values were found only in the incisal region of the incisor. In the incisal region, the values for the bone- and tooth-related areas increased markedly from 2-24 months of age, whereas those for the intermediate area increased slightly but significantly with age. Our findings indicate that the degrees of molecular organization and alignment of collagen fibers in the bone- and tooth-related areas of the ligament are higher than those in the intermediate area and increase near the incisal region and with age. It is also suggested that the collagen fibers in the intermediate area remain immature along the long axis of the incisor throughout the life span of the animal.

Age Factors↗