MTA: the new material of choice for pulp capping

140329 C Boksman feature

Drs. Leendert (Len) Boksman and Manfred (Manny) Friedman delve into the benefits of MTA

The use of MTA (Angelus, Londrina,  Brazil/Clinician’s Choice Dental Products, New Milford, Connecticut) (Figure 1) has revolutionized endodontics, since its introduction to dentistry in 1993.1 (It has been on the dental market since about 1998.)


In the years since, it has proven to be an exceptional material with a wide range of clinical uses, all scientifically and clinically proven.2-4

Initially recommended as a material for filling root end surgical preparations and for perforation repair, this material is also advocated for immediate apical sealing in teeth with open apices,5 pulpotomies, apexification, or apexogenesis in vital teeth with open apices,6-9 and other endodontic and reparative procedures. The extraordinary success in perforation repair since its introduction has motivated its use in these many other areas. This article will look at the success, practicality, and scientific basis for use in pulp capping procedures, particularly in permanent teeth, as MTA has been described very recently as “the material of choice”10 for this treatment.

Properties of MTA

MTA stands for mineral trioxide aggregate, denoting the three dominant oxides in the material’s composition — namely, calcium, aluminum, and selenium. Its particle sizes are strictly controlled during manufacturing, as they all need to be less than 10 microns, so that the material may be completely hydrated. MTA has a similar mechanism of action to calcium hydroxide11 in that the main component of the material, calcium oxide, when in contact with a humid environment, is converted into calcium hydroxide.12 This results in a high pH of 12.5, making its surroundings inhospitable for bacterial growth, and producing an antibacterial effect for a long period of time. But unlike calcium hydroxide products, such as DYCAL® (Dentsply, York, Pennsylvania), MTA Angelus (Angelus Dental Solution, Londrina,  Brazil/Clinician’s Choice Dental Products, New Milford, Connecticut) has very low solubility, so it maintains a hard, excellent marginal seal. Finally, unlike most dental materials, MTA actually needs moisture to set, so it thrives in a moist environment. Of the commercially available MTA products, MTA Angelus is well suited for pulp capping procedures due to its setting time of 10 minutes, compared with the 4-hour setting time of the other commercially available MTA. It is also packaged in airtight bottles, allowing the practitioner to use only what is exactly needed without introducing undue moisture into the remainder. 

Use of MTA for direct pulp capping

140329 C Boksman 01This combination of desirable qualities makes MTA “the material of choice” for cases of pulp exposure in both primary teeth and permanent teeth13,14 (Figures 2-4). Pulpal exposure is inevitable when excavating many large carious lesions. While many dentists are hesitant to perform direct pulp capping procedures due to previously unpredictable results with conventional materials, MTA is a more predictable and reliable material for direct pulp capping teeth, with reversible pulpitis, as borne out by numerous clinical and histological studies.15-19 Mente, et al., recently concluded, “MTA appears to be more effective than calcium hydroxide for maintaining long-term pulp vitality after direct pulp capping.”20 Numerous other studies show much promise in the long-term health of pulps that have been capped using MTA, and years of clinical use have demonstrated the superlative ability of this material in dentin bridge formation (Figures 5-7).21,22

MTA clinical case presentation

A young female patient presented to the dental office with a large carious exposure on the distal of tooth No. 30, as evidenced by the radiograph in Figure 8. Since there was no evidence of periapical rarefaction and no spontaneous pain, it was decided to place a direct pulp cap, if after excavating the caries, the bleeding could be controlled without the use of hemostatic agents. After delivering a mandibular block, and isolation with the rubber dam (Paro Dam – Clinician’s Choice Dental Products, New Milford, Connecticut), the clinical photograph of the distal caries is shown in Figure 9. The initial outline form was created using a pear-shaped 332 carbide bur followed by removal of the soft caries with a round carbide bur (Figure 10). When excavating deep caries and using a regular length bur (Figure 11), the head of the handpiece interferes with adequate vision of the caries removal process. As evidenced by Figure 12, the use of a long shank bur (Figure 13) may complicate access for distal molars, but the distancing of the head of the handpiece from the occlusal cavo-surface margins allows better visualization of the caries removal process. The final removal of the caries is accomplished with the use of a new sterile diamond round bur, which causes less tissue damage to the pulp than the round carbide bur (which also will be contaminated by the caries excavation). The initial carious pulp exposure is shown in Figure 14. A cotton pledget soaked in   5½% sodium hypochlorite (NaOCl) is placed over the pulp tissue and removed when the bleeding has stopped (Figure 15). The area is delicately dried with the use of tissue in cotton pliers (Figure 16). At this point in the procedure, the area is not washed, nor air dried. With the area decontaminated with the bleach and the bleeding stopped (Figure 17), the MTA (Angelus Dental Solution, Londrina,  Brazil/Clinician’s Choice Dental Products, New Milford, Connecticut) is prepared by mixing the powder and liquid according to the manufacturer’s instructions. The MTA is picked up by a plastic instrument, carried to the exposure site, and is deposited by vibrating the plastic instrument with an ultrasonic tip (Figure 18). Figure 19 shows the first increment placed. Similarly, a second increment is carried to the exposure site and is deposited by the vibration of the ultrasonic (Figure 20). The vibration simplifies the placement of the MTA with the material smoothly flowing from the plastic instrument and adapting well to the tooth structure facilitating a good seal. To protect the MTA during its setting, a light-cured glass ionomer (Fuji 2 LC GC America, Alsip, Illinois) is injected precisely over the MTA site with a Skini Syringe and Endo-Eze® canula (Ultradent Products, Salt Lake City, Utah) (Figures 21, 22) and fully light cured with a Valo® broad spectrum curing light (Figure 23). After careful cutback of the glass ionomer cement and a cleaning of all the margins, a Triodent contoured matrix band was placed, followed by the insertion of a Wave-Wedge. The Wave-Wedge does not cause separation but only serves to adapt the matrix gingivally. A Triodent V3 green molar ring (Triodent) was placed to create tooth separation, and the band was burnished with a ball burnisher to confirm contact with tooth No. 31 (Figure 24). Ultra-Etch® was placed for 15 seconds over the glass ionomer, remaining dentin, and enamel margins (Figures 25, 26), gently washed, and lightly dried. A single coat of the fifth-generation bonding agent MPa (Clinician’s Choice Dental Products, New Milford, Connecticut) was applied with a micro-brush (Figure 27), air thinned, and the ethanol solvent evaporated. After light curing with the Valo, the A2 Cosmedent Nano composite (Cosmedent) was incrementally placed, first laterally to decrease the C factor vectors, light cured, and then the center valley filled in, adapted, and light cured (Figure 28). After initial recapitulation of the occlusal anatomy with a 7802 bur (Figure 29), the rubber dam was removed, and a diamond impregnated Groovy Occlusal polishing point (Clinician’s Choice Dental Products, New Milford, Connecticut) (Figure 30) was used to create the final polish of the Nano-filled composite. The final restoration is shown in Figure 31 with the final postoperative radiograph (Figure 32) showing the close adaptation of the MTA, glass ionomer and the Cosmedent Nano.

Summary statement

The clinical and research evidence clearly support the use of MTA as the “new” pulp capping material of choice.





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