الفهرس 
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Abstract
Treated dentin matrix has recently been shown to be a suitable scaffold for human dentin regeneration because of its high bioinductive properties. This study aimed to produce a novel injectable Treated dentin matrix hydrogel (TDMH) and to assess its clinical and radiographic success after direct pulp capping done in traumatically exposed permanent posterior teeth with that of Biodentine and MTA, and to study histologically the pulpal response to these pulp capping materials in sound premolars scheduled to be extracted for orthodontic reasons.
Forty five patients from those attending in the clinic of the Conservative Dentistry Department, Faculty of Dentistry, Alexandria University subjected to accidental traumatic pulp exposures by undergraduate dental students were allocated for this study. For each patient, a pulp capping procedure was done. TDMH was composed of TDM powder (500 μm particle size) and sodium alginate as an injectable scaffold. The prepared hydrogel was transferred into a single syringe to get rid from excess solution and obtain uniform injectable hydrogel mass. Under complete isolation, exposed pulps were capped with different materials (n=15): TDMH, Biodentine and MTA respectively. The cavities in all groups were restored using RMGIC then covered with resin composite restorations. Patients in all groups returned to the clinic for clinical and radiographic evaluation at the following 3, 6, 12, 18 and 24 months. Tomographic data, including thickness and density of formed dentin bridges were evaluated at the end of the study period compared to the base line. Pulp sensitivity was evaluated throughout the study period using thermal testing and electric pulp tester.
For the histological study, 30 intact fully erupted premolars scheduled to be extracted for orthodontic reasons were further included. After pulp capping procedure, the capped teeth were divided into three equal groups (n=10): TDMH, Biodentine and MTA
respectively. The teeth were extracted after 2 weeks and 2 months intervals, stained with hematoxylin-eosin, and categorized by using a histologic scoring system. Statistical analysis was performed using Chi- Square and Kruskal Wallis test (P=0.05).
During the follow-up period, all patients were asymptomatic with no clinical signs and symptoms and revealed no radiographic signs of pathosis. However, tomographic evaluation showed the tested materials to have different levels of impact on formed dentin bridges with TDMH group resulted in significantly superior dentin bridges of a higher radiodensity and thickness than Biodentine and MTA. Moreover, histological analysis after 2 months showed complete bridge formation and absence of inflammatory pulp response with no significant differences between groups. However, the formed dentin was significantly thicker with TDMH group with layers of well-arranged odontoblasts found to form homogenous tubular structure with numerous dentinal tubule lines showing positive trend to dentin regeneration.
TDMH has a greater potential to induce dentin bridge formation than Biodentine and MTA under standardized conditions, suggesting its suitability as a direct pulp capping material in future clinical applications. TDMH could achieve dentin regeneration and conservation of pulp vitality, and might serve as a promising natural substitute in restoring in vivo dentin defect in direct pulp capping procedure. Biodentine may be also considered a promising alternative to MTA in direct pulp capping procedure.