Location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges.
OBJECTIVE
To assess the location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges by using light and transmission electron microscopy techniques and immunohistochemical staining localization.


METHODS
Prior to the study, an animal use protocol form was reviewed and approved by the Screening Committee for Animal Research of the Tokyo Medical and Dental University. Exposed monkey pulps were capped with a hard-set calcium hydroxide and histopathologically evaluated at 3, 14, 21, 30 and 90 days, using light microscopy with silver staining and transmission electron microscopy to differentiate structural features of interodontoblastic collagen fibres. In addition, an attempt was made to identify and to differentiate between several types of collagen and fibronectin using immunohistochemical localization techniques.


RESULTS
At 14 days, interodontoblastic collagen fibres were observed extending from the original dentine, passing through the odontoblasts, and consisted of two portions: a thick fibril and a thin fibril. At 21 days, interodontoblastic collagen fibres were seen penetrating into the predentine and becoming incorporated into the mineralized dentine. At 30 days, interodontoblastic collagen fibres reached the cell process. Although interodontoblastic collagen fibres were no longer observed near the odontoblastoid cells at the area of the newly formed tubular dentine, interodontoblastic collagen fibres were observed embedded within the primary formed dentine bridge. Immunohistochemical staining demonstrated type I collagen and fibronectin within the interodontoblastic collagen fibres.


CONCLUSIONS
Interodontoblastic collagen fibres were routinely detected throughout early dentine bridges. Interodontoblastic collagen fibres are thought to be important for initial dentine bridging to induce and support a dentinogenesis framework.
Kitasako
Y
Y
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. y.kitasako.odnt@dent.tmd.ac.jp
Shibata
S
S
Cox
C F
CF
Tagami
J
J
D000818:Animals; D002126:Calcium Hydroxide / Q000494:pharmacology*; D002454:Cell Differentiation; D003094:Collagen / Q000502:physiology / Q000648:ultrastructure*; D003785:Dental Pulp Capping / Q000379:methods; D003809:Dentin, Secondary / Q000139:chemically induced* / Q000648:ultrastructure; D003810:Dentinogenesis / Q000502:physiology; D005109:Extracellular Matrix / Q000648:ultrastructure; D007150:Immunohistochemistry; D008251:Macaca; D009804:Odontoblasts / Q000648:ultrastructure; D016622:Silver Staining
D003094:Collagen; D002126:Calcium Hydroxide