2002 Fiscal Year Final Research Report Summary
Cellular events at the onset of physiological root resorption.
| Project/Area Number |
13671924
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Matsumoto Dental University |
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Principal Investigator |
SAHARA Noriyuki Matsumoto Dental University, Dentistry, Associate Professor, 歯学部, 助教授 (70064699)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Deciduous teeth / Root resorption / Rabbit / Odontoclast / Dental Follicle |
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| Research Abstract |
For elucidation of how physiological root resorption of deciduous teeth is initiated, the cellular events that occur surrounding the root of rabbit deciduous teeth prior to and at the onset of physiological root resorption were observed by means of light and electron microscopy.
The present investigation was focus on the physiological root resorption of deciduous lower second molar in rabbit from day 0 to 5 postnatally. At birth, the deciduous molar has not erupted yet, and no TRAP-positive cell could be found surrounding tissue adjacent to the root of the deciduous tooth. TRAP-positive mononuclear cells were initially detected in the coronal portion of the dental follicle of the permanent tooth at day I postnatally. TRAP-positive mononuclear cells then appeared in the cementoblast layer immediately adjacent to the surface of deciduous roots. At that time, cell-cell contact was frequently observed between these mononuclear cells and cementoblasts. During 3-5 days postnatally, the number of TRAP-positive multinucleated cells on the root surface gradually increased. They had well-developed ruffled borders and made typical resorption lacunae on the root surface of deciduous tooth. During this early postnatal period, neither inflammatory cells nor necrotic tissue could be observed surrounding the deciduous root. This study demonstrates that the dental follicle of the permanent tooth as well as the connective tissue adjacent to the deciduous root might play important role on site- and time-specific recruitment, development and activation of odontoclasts prior to and at the onset of the physiological root resorption.
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