Bioceramic materials in endodontics

Mineral trioxide aggregate (MTA) has been recommended for various uses in endodontics. Two previous publications provided a comprehensive list of articles from November 1993-September 2009 regarding the chemical and physical properties, sealing ability, antibacterial activity, leakage, and biocompatibility of MTA. The purpose of Part III of this literature review is to present a comprehensive list of articles regarding animal studies, clinical applications, drawbacks, and mechanism of action of MTA. A review of the literature was performed by using electronic and hand-searching methods for the clinical applications of MTA in experimental animals and humans as well as its drawbacks and mechanism of action from November 1993-September 2009. MTA is a promising material for root-end filling, perforation repair, vital pulp therapy, and apical barrier formation for teeth with necrotic pulps and open apexes. Despite the presence of numerous case reports and case series regarding these applications, there are few designed research studies regarding clinical applications of this material. MTA has some known drawbacks such as a long setting time, high cost, and potential of discoloration. Hydroxyapatite crystals form over MTA when it comes in contact with tissue synthetic fluid. This can act as a nidus for the formation of calcified structures after the use of this material in endodontic treatments. On the basis of available information, it appears that MTA is the material of choice for some clinical applications. More clinical studies are needed to confirm its efficacy compared with other materials. Copyright (c) 2010. Published by Elsevier Inc.

This in vitro study used rhodamine B fluorescent dye and a confocal microscope to evaluate the sealing ability of amalgam, super EBA, and a mineral trioxide aggregate when used as root end filling materials. Thirty single-canal teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. After application of nail polish to the external surface, the apical 3 mm of each root was resected and 3-mm deep root end preparations were made. The roots were randomly divided into three groups and the root end preparations filled with the experimental materials. All roots were then exposed to an aqueous solution of rhodamine B fluorescent dye for 24 h, longitudinally sectioned, and the extent of dye penetration measured using a confocal microscope. Statistical analysis showed that the mineral trioxide aggregate leaked significantly less than amalgam and super EBA.

Mineral trioxide aggregate (MTA) has been shown to be bioactive because of its ability to produce biologically compatible carbonated apatite. This study analyzed the interaction of MTA and white Portland cement with dentin after immersion in phosphate-buffered saline (PBS). Dentin disks with standardized cavities were filled with ProRoot MTA, MTA Branco, MTA BIO, white Portland cement + 20% bismuth oxide (PC1), or PC1 + 10% of calcium chloride (PC2) and immersed in 15 mL of PBS for 2 months. The precipitates were weighed and analyzed by scanning electron microscopy (SEM) and x-ray diffraction. The calcium ion release and pH of the solutions were monitored at 5, 15, 25, and 35 days. The samples were processed for SEM observations. Data were analyzed by using analysis of variance or Kruskall-Wallis tests. Our findings revealed the presence of amorphous calcium phosphate precipitates with different morphologies. The apatite formed by the cement-PBS system was deposited within collagen fibrils, promoting controlled mineral nucleation on dentin, observed as the formation of an interfacial layer with tag-like structures. All the cements tested were bioactive. The cements release some of their components in PBS, triggering the initial precipitation of amorphous calcium phosphates, which act as precursors during the formation of carbonated apatite. This spontaneous precipitation promotes a biomineralization process that leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface.