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Ultrastructure (SEM) of dentine bridging in the human dental pulp.

This study was designed to investigate by SEM the ultrastructure of the dentinal bridge formed upon pulp capping and its attachment to the contiguous dentinal walls. The pulps of 20 sound premolars and third molars were deliberately exposed and capped with a calcium hydroxide paste, Pulpdent. After 4 to 15 weeks the teeth were extracted. SEM observations suggested complete bridging, increasing in thickness after succeeding postoperative periods. Cross-sections of the specimens older than 6 weeks showed the presence of three different layers within the bridges: the superior amorphous layer was composed of tissue debris and Ca(OH)2, in the medial portion a coarse meshwork of fibers was identified as fibrodentine and the pulpal aspects exhibited tubularlike orthodentinal structures. The bridge attachment was secured by bundles of fibres linking the intertubular dentine of the pulpal walls with the dentine of the neodentinal bridge.