Immunohistochemical Study of Human Teeth Pulp Capped With Mineral Trioxide Aggregate (MTA) and Novel Endodontic Cement (NEC)

• histologic study of: 1-mean thickness of formed dentinal bridge 2-morphology of formed dentinal bridge 3-intensity of pulp inflammation 4-odontoblastic layer [ Time Frame: 2 weeks and 8 weeks ] [ Designated as safety issue: No ]
  

• expression of Fibronectin and Tenascin by immunohistochemistry on a scale of 1 to 3: (a) 1 equals no staining; (b) 2 equals light-medium staining; (c) 3 equals medium-heavy staining for the marker [ Time Frame: 2 weeks and 8 weeks ] [ Designated as safety issue: No ]
  

Capping of the exposed pulp is indicated for reversible pulp tissue injury after physical or mechanical trauma in developing or mature teeth.The response to direct pulp capping with materials such as MTA or NEC is the formation of dentin barrier, resulting from the recruitment and proliferation of undifferentiated cells.

Different materials can be used to induce dentinal bridge formation.MTA has been introduced as a proper material to induce dentinal bridge formation,with greater mean thickness of dentinal bridge and less inflammation compared to traditional materials like calcium hydroxide. Although biocompatible, MTA has a poor handling characteristic, delay setting time, off-white color, and it is almost expensive.The Novel Endodontic Cement (NEC) has been introduced to combine reasonable characteristics of MTA with appropriate chemical properties, setting time, color, and handling characteristics.

The extracellular matrix (ECM) of pulp comprises a variety of proteins and polysaccharides, forming a neat network. The ECM components can induce either reactionary or reparative dentin formation. Fibronectin (FN) and tenascin (TNC) are the two major glycoproteins involved in wound healing and odontogenesis.

Fibronectins (FNs) are a class of high molecular weight adhesive proteins composed of two very large subunits. It has a variety of cell functions, such as adhesion, migration, growth, and differentiation. Furthermore FN may be involved in the polarization and migration of odontoblasts.

Tenascin is a large oligomeric glycoprotein of the ECM secreted by fibroblasts and glial cells in tissue cultures. It has also been identified in pulp and more prominent in dentinogenesis. TN has been shown to be important in the differentiation of odontoblasts. Therefore, it may be associated with secondary dentin formation, when pulp cells differentiate into odontoblasts in response to physiologic stimuli.

Although dentin bridge formation has been reported,using different materials such as MTA and NEC in direct pulp cap, but the exact mechanism is not well understood. Immunohistochemistry, using different markers, may be useful in developing the molecules involved in this process.

Moreover,response of dental pulp to different pulp capping materials can be studied,including mean thickness of dentinal bridge, morphology of dentinal bridge, and intensity of pulp inflammation and presence of odontoblast cells.