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Compend Contin Educ Dent. Author manuscript; available in PMC 2016 July 27. Published in final edited form as: Compend Contin Educ Dent. 2015 April ; 36(4): 247–264.
MTA: A Clinical Review Peter Z Tawil, DMD, MS, FRCD(C), Dip. ABE, Derek J. Duggan, BDentSc, MS, Dip. ABE, and Johnah C. Galicia, DMD, MS, PhD
Abstract
Author Manuscript
MTA has been a revolutionary material in endodontics. Since it’s introduction in the 1990’s several studies have demonstrated its use in several clinical applications. MTA has been extensively studied and is currently used for perforation repairs, apexifications, regenerative procedures, apexogenesis, pulpotomies & pulp capping. This article will review the history, composition, research findings and clinical applications of this versatile material.
Introduction
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MTA stands for Mineral Trioxide Aggregate. Over the past two decades, MTA has become one of the most widely studied endodontic materials.1–3 The trioxide aggregate in MTA consists of calcium, aluminum and selenium. MTA has several desirable properties in terms of its biocompatiblity, bioactivity, hydrophilicity, radiopacity, sealing ability and low solubility. The most important of these properties in dentistry are its biocompatibility and sealing ability. High biocompatibility encourages optimal healing responses. This has been observed histologically with the formation of new cementum in periradicular tissues area and a low inflammatory response with bridge formation in the pulp space.4,5 The seal achieved is due to its expansion and contraction properties being very similar to dentin which results in high resistance to marginal leakage and to bacterial migration into the root canal system. A stable barrier to bacterial and fluid leakage is one of the key factors which facilitates clinical success.
Author Manuscript
A very practical advantage of MTA is that it sets in the moist environment omnipresent in dentistry. Unlike many other dental materials, MTA sets in a moist environment. When in contact with moisture, it’s main component, which is calcium oxide, converts into calcium hydroxide which many clinicians will be familiar with.6 This conversion results in a high pH microenvironment which has beneficial antibacterial effects. Unlike calcium hydroxide, however, this material has very low solubility and maintains its physical integrity after placement. MTA materials are derived from a Portland cement parent compound. Although these compounds are similar in some respects, Portland cement and MTA are not identical.7 MTA products undergo additional processing and purification. MTA products when compared to Portland cements have a smaller mean particle size and contain fewer toxic heavy metals.8 MTA was first introduced in the dental literature in 1993 and received FDA approval in 1998.9,10 In 1999 Pro Root MTA (Dentsply Tulsa Dental Specialties, Johnson City, TN) was the first commercially available MTA product to be launched in the United States (Figure
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1A). MTA Angelus (Angelus, Londrina, Brazil / Clinician’s Choice, New Milford, CT) was launched in Brazil in 2001 and received FDA approval in 2011, making it available in the United States (Figure 1B). MTA Angelus exhibits a reduced setting time, is sold in containers that permit more controlled dispensing and posesses the same desirable properties as traditional MTA.6,11–13 While the original ProRoot MTA is sold in single-use packets, the newer MTA Angelus is packaged in airtight bottles that allow practitioners to dispense a small volume of powder while resealing the remainder in its original container for future use.
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Traditional ProRoot MTA takes about 2 to 3 hours to set. MTA Angelus sets within 15 minutes of being prepared. The decreased setting time is sometimes desirable as clinicians can ensure the material is set at the time of placement and can proceed with their restorative procedures without worrying about MTA washout. The reduced setting time of MTA Angelus is a result of reducing the concentration of calcium sulfate, which is the substance responsible for the longer setting time in the original formulation. MTA comes in grey and white versions. The first MTA products were grey and most of the initial research was done on this formulation. Due to staining concerns that were reported when MTA residues were left in the clinical crown, the white version of MTA was introduced to the market in 2002.7 White MTA has shown a decreased potential for staining but clinicians should still be diligent in removing all traces of MTA prior to restoring the coronal access of teeth in the aesthetic zone.14 The difference between the two colors is mostly due to a decrease in the concentrations of iron, aluminum, and magnesium oxides in white MTA.7,15 The major difference is in the relative proportion of iron oxide where white MTA was found to have 90.8% less when compared to the original grey MTA variety.15 Even with these modifications, white MTA still possesses similar properties to grey MTA cement.11,16,17 When first introduced, clinicians had difficulty handling MTA due to its wet sand-like consistency, unlike most other conventional dental materials. Following the introduction on the market of several customized application devices, the handling and application of this material has become more predictable.
Clinical Applications
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Over 24 million endodontic procedures are performed on an annual basis in the United States with 5.5% of these procedures being advanced treatments such as periapical microsurgeries, perforation repairs and apexification treatments.18 All of these endodontic procedures and some operative procedures have greatly benefitted from the availability of MTA and they are discussed in turn. Pulp Capping Pulpal exposures are sometimes inevitable when addressing large carious lesions. While some dentists are hesitant to perform direct pulp capping procedures due to its documented unpredictability as a definitive treatment option, MTA may help to improve the outcome of this treatment in the years ahead. MTA has the advantage of being less soluble than calcium hydroxide and offers an enhanced seal due to its setting expansion which hermetically seals
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the pulp space, preventing bacterial contamination from the outside. Studies have shown that in asymptomatic cases or in cases with reversible pulpits (where the infection has not spread into the pulp chamber proper), MTA pulp capping can serve as a viable treatment option.19,20 Histological studies are also showing less inflammation and more dentinal bridging when MTA is placed compared to conventional pulp capping with calcium hydroxide.5 In pulp capping, the rapid 15 minutes set of MTA Angelus allows the final restoration to be placed without delay and in direct contact with the set MTA. Vital Pulp Therapy (Pulpotomy and Apexogenesis)
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In cases of irreversible pulpitis where bacteria have invaded the pulp chamber, a pulpotomy procedure can sometimes be considered.21–23 This procedure is also termed apexogenesis because its ultimate goal is to facilitate the complete formation of the apex and root. This procedure is carried out in immature teeth with incomplete root formation that contain vital pulp tissue. The radicular pulp which is considered to be relatively free of inflammation is retained. When this is done, at a histological level, odontoblasts will differentiate, dentin continues to be laid down and root development should continue. This will result in thickening of the root walls (which reduces the risk of root fracture) and apical closure should occur (apexogenesis), forming a natural apical constriction that would facilitate any future root canal obturation procedures. Clinical procedure—Once in the pulp chamber, clinicians should use a diamond bur as it will cauterize the tissue and minimize the bleeding. Once that is done the area should be disinfected with an antimicrobial agent (sodium hypochlorite or chlorhexidine) followed by a saline rinse. Hemostasis is obtained with light pressure from a damp cotton pellet. The pellet is removed after a couple of minutes and the area is then ready to be filled with MTA.
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Apexification The treatment of a necrotic pulp in an immature root has always presented a challenge to clinicians due to the lack of an apical stop. This has classically been addressed with long term calcium hydroxide treatment which may require several years of treatment time, involve multiple visits and theoretically at least, increase the fracture potential of the root involved.24 MTA has become an excellent predictable alternative to address these issues by creating a biocompatible apical plug in a single visit.25–26
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Clinical procedure—If apical bone loss is present a collagen/gelatin sponge like Gelfoam® can be placed apically so that the MTA can be delivered to the desired working length. This is done by taking a small piece (2×2mm) of Gelfoam® that is pushed down to and through the root apex with an endodontic file. Once this is done, MTA is packed down the canal with a custom fitted cone. The clinician can use a rubber stopper on his gutta percha cone to know the exact length of MTA placed in the apical third (Figure 2B). Once the apical third is sealed with 3–5mm of MTA, the remaining coronal canal space can be backfilled using a warm gutta-percha technique (Figure 2C).
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Regeneration
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The treatment of a necrotic pulp in an immature root with very thin walls is problematic due to the high potential for root fracture. Regeneration of the dentin-pulp complex is a contemporary approach that involves disinfecting the root canal system with a triple antibiotic paste followed by tissue repair and regeneration.27–28 This should allow continued thickening of the lateral dentinal walls through deposition of new dentin-like hard tissue.27–28 More research is still needed to exactly assess if and how this newly deposited dentin-like hard tissue strengthens the pre-existing thin root.
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Clinical procedure—Regeneration of the endodontic pulp space is indicated for cases with very thin dentinal walls and an open apex that is over 1mm in diameter radiographically (Figure 3A). Disinfection of the root canal system is performed using sodium hypochlorite irrigation followed by a triple antibiotic paste dressing that is left in place for one week. At the second visit, EDTA is used to condition the dentin walls (which results in the release of growth factors) and bleeding is stimulated in the periapical tissues (where stem cells are located), with the aim of filling the pulp space with a stable blood clot (serving as the scaffold). MTA is then placed at the canal orifice in contact with the clot to protect it from coronal micro-leakage (Figure 3C). In time, the clot should be replaced with a reparative tissue of variable composition and the root walls should continue to thicken due to the deposition of a dentin-like material on the pre-existing root dentin.27–28 Root Perforation
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Perforations are generally the result of iatrogenic conditions in which a communication between the pulp canal and the periradicular tissue occurs during either access preparation or during canal shaping procedures. Perforations can also happen in cases of internal root resorption, where the entire thickness of the root becomes affected by the resorptive process. Due to the excellent sealing ability and biocompatibility of MTA, it has been used to repair root perforations with predictable results.29–30 Clinical procedure—Once a perforation occurs, one has to assess the extent of that perforation. If there is an adjacent bony defect, the bony defect should first be filled with an osteoconductive or ostoinductive material. This can be done with a bone graft, calcium sulfate or collagen/gelatin sponge (Figure 4A). The dentinal portion of the tooth that has been perforated is then restored with MTA (Figure 4B). Root-End Filling
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A root-end filling (also known as a retrofilling) is performed in endodontics when an extraradicular microsurgical approach is needed to address endodontic pathology. Most cases treated surgically cannot be predictably treated by orthograde conventional root canal methods due to complex canal anatomy or due to iatrogenic misadventures during root canal treatments.31,32 MTA exhibits excellent physical sealing properties, and furthermore, there is an additional biological seal obtained by the proliferation of cells directly on the cementum during the healing process.4,32
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Clinical procedure—Once the apical 3mm of the root has been resected (Figure 6B), the canal system is then opened and cleaned with surgical ultrasonic tips to create the retropreparation (Figure 6C). After this is completed, the retro-preparation is dried and MTA is then placed and condensed in that space creating the retro-filling (Figure 6D).
Conclusion
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Scientific research has demonstrated the effectiveness of traditional MTA when used in a range of endodontic procedures. The history, chemical composition and clinical applications of MTA have been discussed in this review paper. When sealing effectiveness and biocompatibility are considered, there is no other dental material on the market similar to MTA. With the recent introduction of a fast setting MTA which also offers excellent handling properties, MTA-based products are likely to remain at the heart of good dental practice for many years to come.
Supplementary Material Refer to Web version on PubMed Central for supplementary material.
References
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1. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review--Part I: chemical, physical, and antibacterial properties. J Endod. 2010 Jan; 36(1):16–27. [PubMed: 20003930] 2. Torabinejad M, Parirokh M. Mineral trioxide aggregate: a comprehensive literature review--part II: leakage and biocompatibility investigations. J Endod. 2010 Feb; 36(2):190–202. [PubMed: 20113774] 3. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review--Part III: Clinical applications, drawbacks, and mechanism of action. J Endod. 2010 Mar; 36(3):400–13. [PubMed: 20171353] 4. Tawil PZ, Trope M, Curran AE, Caplan DJ, Kirakozova A, Duggan DJ, Teixeira FB. Periapical microsurgery: an in vivo evaluation of endodontic root-end filling materials. J Endod. 2009 Mar; 35(3):357–62. [PubMed: 19249595] 5. Faraco IM Jr, Holland R. Response of the pulp of dogs to capping with mineral trioxide aggregate or a calcium hydroxide cement. Dent Traumatol. 2001 Aug; 17(4):163–6. [PubMed: 11585142] 6. Duarte MA, Demarchi AC, Yamashita JC, Kuga MC, de Fraga SC. Ph and calcium ion release of 2 root-end filling materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003; 95(3):345– 347. [PubMed: 12627108] 7. Dammaschke T, Gerth HU, Züchner H, Schäfer E. Chemical and physical surface and bulk material characterization of white ProRoot MTA and two Portland cements. Dent Mater. 2005 Aug; 21(8): 731–8. [PubMed: 15935463] 8. Islam I, Chng HK, Yap AU. Comparison of the physical and mechanical properties of MTA and port-land cement. J Endod. 2006 Mar; 32(3):193–7. [PubMed: 16500224] 9. Lee SJ, Monsef M, Torabinejad M. Sealing Ability of Mineral Trioxide Aggregate for Repair of Lateral Root Perforations. Journal of Endodontics. Nov; 1993 19(11):541–544. [PubMed: 8151240] 10. Schmitt D, Lee J, Bogen G. Multifaceted use of ProRoot MTA root canal repair material. Pediatr Dent. 2001 Jul-Aug;23(4):326–30. [PubMed: 11572491] 11. Menezes R, Bramante CM, Letra A, Carvalho VG, Garcia RB. Histologic evaluation of pulpotomies in dog using two types of mineral trioxide aggregate and regular and white Portland cements as wound dressings. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004 Sep; 98(3): 376–9. [PubMed: 15356480]
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12. Koulaouzidou EA, Economides N, Beltes P, Geromichalos G, Papazisis K. In vitro evaluation of the cytotoxicity of ProRoot MTA and MTA Angelus. J Oral Sci. 2008 Dec; 50(4):397–402. [PubMed: 19106466] 13. Lolayekar N, Bhat SS, Hegde S. Sealing ability of ProRoot MTA and MTA-Angelus simulating a one-step apical barrier technique--an in vitro study. J Clin Pediatr Dent. 2009 Summer;33(4):305– 10. [PubMed: 19725236] 14. Ioannidis K, Mistakidis I, Beltes P, Karagiannis V. Spectrophotometric analysis of coronal discolouration induced by grey and white MTA. Int Endod J. 2013 Feb; 46(2):137–44. [PubMed: 22823058] 15. Asgary S, Parirokh M, Eghbal MJ, Brink F. Chemical differences between white and gray mineral trioxide aggregate. J Endod. 2005 Feb; 31(2):101–3. [PubMed: 15671818] 16. Frenkel G, Kaufman A, Ashkenazi M. Clinical and radiographic outcomes of pulpotomized primary molars treated with white or gray mineral trioxide aggregate and ferric sulfate--long-term follow-up. J Clin Pediatr Dent. 2012 Winter;37(2):137–41. [PubMed: 23534318] 17. Eskandarizadeh A, Shahpasandzadeh MH, Shahpasandzadeh M, Torabi M, Parirokh M. A comparative study on dental pulp response to calcium hydroxide, white and grey mineral trioxide aggregate as pulp capping agents. J Conserv Dent. 2011 Oct; 14(4):351–5. [PubMed: 22144801] 18. Nash KD, Brown LJ, Hicks ML. Private practicing endodontists: production of endodontic services and implications for workforce policy. J Endod. 2002 Oct; 28(10):699–705. [PubMed: 12398168] 19. Farsi N, Alamoudi N, Balto K, Al Mushayt A. Clinical assessment of mineral trioxide aggregate (MTA) as direct pulp capping in young permanent teeth. J Clin Pediatr Dent. 2006 Winter;31(2): 72–6. [PubMed: 17315797] 20. Bogen G, Kim JS, Bakland LK. Direct pulp capping with mineral trioxide aggregate: an observational study. J Am Dent Assoc. 2008 Mar; 139(3):305–15. [PubMed: 18310735] 21. Camp JH. Diagnosis dilemmas in vital pulp therapy: treatment for the toothache is changing, especially in young, immature teeth. J Endod. 2008 Jul.34:S6–12. [PubMed: 18565375] 22. Witherspoon DE. Vital pulp therapy with new materials: new directions and treatment perspectives--permanent teeth. J Endod. 2008 Jul.34:S25–8. [PubMed: 18565368] 23. Barrieshi-Nusair KM, Qudeimat MA. A prospective clinical study of mineral trioxide aggregate for partial pulpotomy in cariously exposed permanent teeth. J Endod. 2006 Aug; 32(8):731–5. [PubMed: 16861071] 24. Andreasen JO, Farik B, Munksgaard EC. Long-term calcium hydroxide as a root canal dressing may increase risk of root fracture. Dent Traumatol. 2002 Jun; 18(3):134–7. [PubMed: 12110105] 25. Witherspoon DE, Ham K. One-visit apexification: technique for inducing root-end barrier formation in apical closures. Pract Proced Aesthet Dent. 2001 Aug; 13(6):455–60. [PubMed: 11544818] 26. Witherspoon DE, Small JC, Regan JD, Nunn M. Retrospective analysis of open apex teeth obturated with mineral trioxide aggregate. J Endod. 2008 Oct; 34(10):1171–6. [PubMed: 18793914] 27. Banchs F, Trope M. Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol? J Endod. 2004 Apr; 30(4):196–200. [PubMed: 15085044] 28. Miller EK, Lee JY, Tawil PZ, Teixeira FB, Vann WF Jr. Emerging therapies for the management of traumatized immature permanent incisors. Pediatr Dent. 2012 Jan-Feb;34(1):66–9. [PubMed: 22353461] 29. Mente J, Leo M, Panagidis D, Saure D, Pfefferle T. Treatment outcome of mineral trioxide aggregate: repair of root perforations-long-term results. J Endod. 2014 Jun; 40(6):790–6. [PubMed: 24862705] 30. Main C, Mirzayan N, Shabahang S, Torabinejad M. Repair of root perforations using mineral trioxide aggregate: a long-term study. J Endod. 2004 Feb; 30(2):80–3. [PubMed: 14977301] 31. Chong, BS. Managing endodontic failure in practice. Chicago: Quintessence Publishing Co., Ltd; 2004. p. 123-47. 32. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod. 2006 Jul; 32(7):601–23. [PubMed: 16793466]
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Biographies
Peter Z Tawil, DMD, MS, FRCD(C), Dip. ABE
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Dr. Peter Zahi Tawil started out his college career in Mechanical Engineering at McGill University in Montreal. He then pursued his studies in Dentistry at the Université de Montréal where he received his DMD in 2004. He continued his studies at the University of Rochester where he completed his degree in Advanced Education in General Dentistry. In 2008 he completed his specialty training in Endodontics at the University of North Carolina at Chapel Hill, graduating with a Masters in Endodontics. After completing his studies in Chapel Hill, Dr. Tawil worked as a specialist in private practice in Montreal while serving as an adjunct faculty member at McGill University. Dr. Tawil serves as a speaker for the American Association of Endodontists and has lectured nationally and internationally. He’s currently teaches full time as the Jacob and Charlotte Freedland Term Professor at the University of North Carolina at Chapel Hill. Furthermore, he’s a Fellow of the Royal College of Dentists of Canada and a Diplomate of the American Board of Endodontics.
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Derek J. Duggan, DDS, MS, Dip. ABE
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Dr. Derek Duggan received his dental degree from Trinity College Dublin in 2001. Following 3 years of private practice in both London and Dublin, Dr. Duggan completed a 1 year hospital residency at the Dublin Dental Hospital. He received his Masters in Endodontics from the University of North Carolina in 2008. He then worked for 1 year in a specialist private practice in Dublin. Dr. Duggan joined the Endodontic Department at UNC School of Dentistry in 2009, and is currently the preclinical endodontic course director. As a result of his stewardship, student’s learning experience has been greatly enhanced through short technique videos developed specifically for this course at UNC. Self paced learning is another distinguishing characteristic of this preclinical course. Dr. Duggan has hosted handson courses with colleagues at UNC for several years, including a number of interdepartmental CE courses. He is a Diplomate of the American Board of Endodontists, and continues to enhance his skills by actively engaging in both continuing education as well as interacting with his peers on a national and international level.
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Johnah C. Galicia, DMD, MS, PhD
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Dr. Johnah Galicia received his Masters in Endodontics degree from the University of North Carolina in 2014 as an American Association of Endodontists Foundation Educator Fellow. Prior to that, Dr. Galicia was a postdoctoral fellow at the School of Dentistry of the University of Pennsylvania and of the University of Louisville. He earned a PhD in Oral Biology from Niigata University in Japan and a Diploma in Clinical Dentistry from the University of Rennes 1 in France. He was a general dentist and a faculty member of his dental school alma mater, the Manila Central University in the Philippines, before entering the PhD program. In addition to clinical and academic pursuits, research has been also an integral part of Dr. Galicia’s career. He has co-authored several peer-reviewed articles in reputable international scientific journals and has presented his research in international forums. He is currently an Assistant Professor at the Department of Endodontics of the University of the Pacific School of Dentistry where he also practices endodontics. He has served as a member of the Research and Scientific Affairs Committee of the American Association of Endodontists (AAE) and is presently involved with the Marketing Committee of the AAE Foundation.
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Fig 1.
Fig 1A. ProRoot MTA. Fig 1B. MTA-Angelus.
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Fig 2.
Fig 2A. Pre-operative radiograph. Fig 2B. MTA-Angelus placed in the apical third. Fig 2C. Postoperative radiograph.
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Fig 3A. Pre-operative radiograph showing the aggressive external root resorption and the thin dentinal walls. Fig 3B. Working length confirmation. Fig 3C. Post-operative radiograph. Fig 3D. one year follow up showing a healthy lamina dura and root development. Fig 3E. Three years follow up showing the continued root development.
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Fig 4.
Fig 4A. Calcium sulfate placed in the bony portion of the perforation. Fig 4B. MTAAngelus placed in the dentinal portion of the perforation.
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Fig 5A/5B. Pre-operative radiographs showing the mesial perforation. Fig 5C. MTA perforation repair done and calcium hydroxide medication placed in the canals. Fig 5D. Post-operative radiograph. Fig 5C/D. Two year follow-up radiographs showing the positive outcome.
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Fig 6A. Pre-operative radiograph. Fig 6B. 3mm root resection with methylene blue staining. Fig 6C. Retro-preparation with ultrasonic tip. Fig 6D. MTA-Angelus placed as a retrofilling. Fig 6E. Post-operative radiograph. Fig 6F. Six month follow-up.
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Compend Contin Educ Dent. Author manuscript; available in PMC 2016 July 27. Published in final edited form as: Compend Contin Educ Dent. 2015 April ; 36(4): 247–264.
MTA: A Clinical Review Peter Z Tawil, DMD, MS, FRCD(C), Dip. ABE, Derek J. Duggan, BDentSc, MS, Dip. ABE, and Johnah C. Galicia, DMD, MS, PhD
Abstract
Author Manuscript
MTA has been a revolutionary material in endodontics. Since it’s introduction in the 1990’s several studies have demonstrated its use in several clinical applications. MTA has been extensively studied and is currently used for perforation repairs, apexifications, regenerative procedures, apexogenesis, pulpotomies & pulp capping. This article will review the history, composition, research findings and clinical applications of this versatile material.
Introduction
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MTA stands for Mineral Trioxide Aggregate. Over the past two decades, MTA has become one of the most widely studied endodontic materials.1–3 The trioxide aggregate in MTA consists of calcium, aluminum and selenium. MTA has several desirable properties in terms of its biocompatiblity, bioactivity, hydrophilicity, radiopacity, sealing ability and low solubility. The most important of these properties in dentistry are its biocompatibility and sealing ability. High biocompatibility encourages optimal healing responses. This has been observed histologically with the formation of new cementum in periradicular tissues area and a low inflammatory response with bridge formation in the pulp space.4,5 The seal achieved is due to its expansion and contraction properties being very similar to dentin which results in high resistance to marginal leakage and to bacterial migration into the root canal system. A stable barrier to bacterial and fluid leakage is one of the key factors which facilitates clinical success.
Author Manuscript
A very practical advantage of MTA is that it sets in the moist environment omnipresent in dentistry. Unlike many other dental materials, MTA sets in a moist environment. When in contact with moisture, it’s main component, which is calcium oxide, converts into calcium hydroxide which many clinicians will be familiar with.6 This conversion results in a high pH microenvironment which has beneficial antibacterial effects. Unlike calcium hydroxide, however, this material has very low solubility and maintains its physical integrity after placement. MTA materials are derived from a Portland cement parent compound. Although these compounds are similar in some respects, Portland cement and MTA are not identical.7 MTA products undergo additional processing and purification. MTA products when compared to Portland cements have a smaller mean particle size and contain fewer toxic heavy metals.8 MTA was first introduced in the dental literature in 1993 and received FDA approval in 1998.9,10 In 1999 Pro Root MTA (Dentsply Tulsa Dental Specialties, Johnson City, TN) was the first commercially available MTA product to be launched in the United States (Figure
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1A). MTA Angelus (Angelus, Londrina, Brazil / Clinician’s Choice, New Milford, CT) was launched in Brazil in 2001 and received FDA approval in 2011, making it available in the United States (Figure 1B). MTA Angelus exhibits a reduced setting time, is sold in containers that permit more controlled dispensing and posesses the same desirable properties as traditional MTA.6,11–13 While the original ProRoot MTA is sold in single-use packets, the newer MTA Angelus is packaged in airtight bottles that allow practitioners to dispense a small volume of powder while resealing the remainder in its original container for future use.
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Traditional ProRoot MTA takes about 2 to 3 hours to set. MTA Angelus sets within 15 minutes of being prepared. The decreased setting time is sometimes desirable as clinicians can ensure the material is set at the time of placement and can proceed with their restorative procedures without worrying about MTA washout. The reduced setting time of MTA Angelus is a result of reducing the concentration of calcium sulfate, which is the substance responsible for the longer setting time in the original formulation. MTA comes in grey and white versions. The first MTA products were grey and most of the initial research was done on this formulation. Due to staining concerns that were reported when MTA residues were left in the clinical crown, the white version of MTA was introduced to the market in 2002.7 White MTA has shown a decreased potential for staining but clinicians should still be diligent in removing all traces of MTA prior to restoring the coronal access of teeth in the aesthetic zone.14 The difference between the two colors is mostly due to a decrease in the concentrations of iron, aluminum, and magnesium oxides in white MTA.7,15 The major difference is in the relative proportion of iron oxide where white MTA was found to have 90.8% less when compared to the original grey MTA variety.15 Even with these modifications, white MTA still possesses similar properties to grey MTA cement.11,16,17 When first introduced, clinicians had difficulty handling MTA due to its wet sand-like consistency, unlike most other conventional dental materials. Following the introduction on the market of several customized application devices, the handling and application of this material has become more predictable.
Clinical Applications
Author Manuscript
Over 24 million endodontic procedures are performed on an annual basis in the United States with 5.5% of these procedures being advanced treatments such as periapical microsurgeries, perforation repairs and apexification treatments.18 All of these endodontic procedures and some operative procedures have greatly benefitted from the availability of MTA and they are discussed in turn. Pulp Capping Pulpal exposures are sometimes inevitable when addressing large carious lesions. While some dentists are hesitant to perform direct pulp capping procedures due to its documented unpredictability as a definitive treatment option, MTA may help to improve the outcome of this treatment in the years ahead. MTA has the advantage of being less soluble than calcium hydroxide and offers an enhanced seal due to its setting expansion which hermetically seals
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the pulp space, preventing bacterial contamination from the outside. Studies have shown that in asymptomatic cases or in cases with reversible pulpits (where the infection has not spread into the pulp chamber proper), MTA pulp capping can serve as a viable treatment option.19,20 Histological studies are also showing less inflammation and more dentinal bridging when MTA is placed compared to conventional pulp capping with calcium hydroxide.5 In pulp capping, the rapid 15 minutes set of MTA Angelus allows the final restoration to be placed without delay and in direct contact with the set MTA. Vital Pulp Therapy (Pulpotomy and Apexogenesis)
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In cases of irreversible pulpitis where bacteria have invaded the pulp chamber, a pulpotomy procedure can sometimes be considered.21–23 This procedure is also termed apexogenesis because its ultimate goal is to facilitate the complete formation of the apex and root. This procedure is carried out in immature teeth with incomplete root formation that contain vital pulp tissue. The radicular pulp which is considered to be relatively free of inflammation is retained. When this is done, at a histological level, odontoblasts will differentiate, dentin continues to be laid down and root development should continue. This will result in thickening of the root walls (which reduces the risk of root fracture) and apical closure should occur (apexogenesis), forming a natural apical constriction that would facilitate any future root canal obturation procedures. Clinical procedure—Once in the pulp chamber, clinicians should use a diamond bur as it will cauterize the tissue and minimize the bleeding. Once that is done the area should be disinfected with an antimicrobial agent (sodium hypochlorite or chlorhexidine) followed by a saline rinse. Hemostasis is obtained with light pressure from a damp cotton pellet. The pellet is removed after a couple of minutes and the area is then ready to be filled with MTA.
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Apexification The treatment of a necrotic pulp in an immature root has always presented a challenge to clinicians due to the lack of an apical stop. This has classically been addressed with long term calcium hydroxide treatment which may require several years of treatment time, involve multiple visits and theoretically at least, increase the fracture potential of the root involved.24 MTA has become an excellent predictable alternative to address these issues by creating a biocompatible apical plug in a single visit.25–26
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Clinical procedure—If apical bone loss is present a collagen/gelatin sponge like Gelfoam® can be placed apically so that the MTA can be delivered to the desired working length. This is done by taking a small piece (2×2mm) of Gelfoam® that is pushed down to and through the root apex with an endodontic file. Once this is done, MTA is packed down the canal with a custom fitted cone. The clinician can use a rubber stopper on his gutta percha cone to know the exact length of MTA placed in the apical third (Figure 2B). Once the apical third is sealed with 3–5mm of MTA, the remaining coronal canal space can be backfilled using a warm gutta-percha technique (Figure 2C).
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Regeneration
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The treatment of a necrotic pulp in an immature root with very thin walls is problematic due to the high potential for root fracture. Regeneration of the dentin-pulp complex is a contemporary approach that involves disinfecting the root canal system with a triple antibiotic paste followed by tissue repair and regeneration.27–28 This should allow continued thickening of the lateral dentinal walls through deposition of new dentin-like hard tissue.27–28 More research is still needed to exactly assess if and how this newly deposited dentin-like hard tissue strengthens the pre-existing thin root.
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Clinical procedure—Regeneration of the endodontic pulp space is indicated for cases with very thin dentinal walls and an open apex that is over 1mm in diameter radiographically (Figure 3A). Disinfection of the root canal system is performed using sodium hypochlorite irrigation followed by a triple antibiotic paste dressing that is left in place for one week. At the second visit, EDTA is used to condition the dentin walls (which results in the release of growth factors) and bleeding is stimulated in the periapical tissues (where stem cells are located), with the aim of filling the pulp space with a stable blood clot (serving as the scaffold). MTA is then placed at the canal orifice in contact with the clot to protect it from coronal micro-leakage (Figure 3C). In time, the clot should be replaced with a reparative tissue of variable composition and the root walls should continue to thicken due to the deposition of a dentin-like material on the pre-existing root dentin.27–28 Root Perforation
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Perforations are generally the result of iatrogenic conditions in which a communication between the pulp canal and the periradicular tissue occurs during either access preparation or during canal shaping procedures. Perforations can also happen in cases of internal root resorption, where the entire thickness of the root becomes affected by the resorptive process. Due to the excellent sealing ability and biocompatibility of MTA, it has been used to repair root perforations with predictable results.29–30 Clinical procedure—Once a perforation occurs, one has to assess the extent of that perforation. If there is an adjacent bony defect, the bony defect should first be filled with an osteoconductive or ostoinductive material. This can be done with a bone graft, calcium sulfate or collagen/gelatin sponge (Figure 4A). The dentinal portion of the tooth that has been perforated is then restored with MTA (Figure 4B). Root-End Filling
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A root-end filling (also known as a retrofilling) is performed in endodontics when an extraradicular microsurgical approach is needed to address endodontic pathology. Most cases treated surgically cannot be predictably treated by orthograde conventional root canal methods due to complex canal anatomy or due to iatrogenic misadventures during root canal treatments.31,32 MTA exhibits excellent physical sealing properties, and furthermore, there is an additional biological seal obtained by the proliferation of cells directly on the cementum during the healing process.4,32
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Clinical procedure—Once the apical 3mm of the root has been resected (Figure 6B), the canal system is then opened and cleaned with surgical ultrasonic tips to create the retropreparation (Figure 6C). After this is completed, the retro-preparation is dried and MTA is then placed and condensed in that space creating the retro-filling (Figure 6D).
Conclusion
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Scientific research has demonstrated the effectiveness of traditional MTA when used in a range of endodontic procedures. The history, chemical composition and clinical applications of MTA have been discussed in this review paper. When sealing effectiveness and biocompatibility are considered, there is no other dental material on the market similar to MTA. With the recent introduction of a fast setting MTA which also offers excellent handling properties, MTA-based products are likely to remain at the heart of good dental practice for many years to come.
Supplementary Material Refer to Web version on PubMed Central for supplementary material.
References
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12. Koulaouzidou EA, Economides N, Beltes P, Geromichalos G, Papazisis K. In vitro evaluation of the cytotoxicity of ProRoot MTA and MTA Angelus. J Oral Sci. 2008 Dec; 50(4):397–402. [PubMed: 19106466] 13. Lolayekar N, Bhat SS, Hegde S. Sealing ability of ProRoot MTA and MTA-Angelus simulating a one-step apical barrier technique--an in vitro study. J Clin Pediatr Dent. 2009 Summer;33(4):305– 10. [PubMed: 19725236] 14. Ioannidis K, Mistakidis I, Beltes P, Karagiannis V. Spectrophotometric analysis of coronal discolouration induced by grey and white MTA. Int Endod J. 2013 Feb; 46(2):137–44. [PubMed: 22823058] 15. Asgary S, Parirokh M, Eghbal MJ, Brink F. Chemical differences between white and gray mineral trioxide aggregate. J Endod. 2005 Feb; 31(2):101–3. [PubMed: 15671818] 16. Frenkel G, Kaufman A, Ashkenazi M. Clinical and radiographic outcomes of pulpotomized primary molars treated with white or gray mineral trioxide aggregate and ferric sulfate--long-term follow-up. J Clin Pediatr Dent. 2012 Winter;37(2):137–41. [PubMed: 23534318] 17. Eskandarizadeh A, Shahpasandzadeh MH, Shahpasandzadeh M, Torabi M, Parirokh M. A comparative study on dental pulp response to calcium hydroxide, white and grey mineral trioxide aggregate as pulp capping agents. J Conserv Dent. 2011 Oct; 14(4):351–5. [PubMed: 22144801] 18. Nash KD, Brown LJ, Hicks ML. Private practicing endodontists: production of endodontic services and implications for workforce policy. J Endod. 2002 Oct; 28(10):699–705. [PubMed: 12398168] 19. Farsi N, Alamoudi N, Balto K, Al Mushayt A. Clinical assessment of mineral trioxide aggregate (MTA) as direct pulp capping in young permanent teeth. J Clin Pediatr Dent. 2006 Winter;31(2): 72–6. [PubMed: 17315797] 20. Bogen G, Kim JS, Bakland LK. Direct pulp capping with mineral trioxide aggregate: an observational study. J Am Dent Assoc. 2008 Mar; 139(3):305–15. [PubMed: 18310735] 21. Camp JH. Diagnosis dilemmas in vital pulp therapy: treatment for the toothache is changing, especially in young, immature teeth. J Endod. 2008 Jul.34:S6–12. [PubMed: 18565375] 22. Witherspoon DE. Vital pulp therapy with new materials: new directions and treatment perspectives--permanent teeth. J Endod. 2008 Jul.34:S25–8. [PubMed: 18565368] 23. Barrieshi-Nusair KM, Qudeimat MA. A prospective clinical study of mineral trioxide aggregate for partial pulpotomy in cariously exposed permanent teeth. J Endod. 2006 Aug; 32(8):731–5. [PubMed: 16861071] 24. Andreasen JO, Farik B, Munksgaard EC. Long-term calcium hydroxide as a root canal dressing may increase risk of root fracture. Dent Traumatol. 2002 Jun; 18(3):134–7. [PubMed: 12110105] 25. Witherspoon DE, Ham K. One-visit apexification: technique for inducing root-end barrier formation in apical closures. Pract Proced Aesthet Dent. 2001 Aug; 13(6):455–60. [PubMed: 11544818] 26. Witherspoon DE, Small JC, Regan JD, Nunn M. Retrospective analysis of open apex teeth obturated with mineral trioxide aggregate. J Endod. 2008 Oct; 34(10):1171–6. [PubMed: 18793914] 27. Banchs F, Trope M. Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol? J Endod. 2004 Apr; 30(4):196–200. [PubMed: 15085044] 28. Miller EK, Lee JY, Tawil PZ, Teixeira FB, Vann WF Jr. Emerging therapies for the management of traumatized immature permanent incisors. Pediatr Dent. 2012 Jan-Feb;34(1):66–9. [PubMed: 22353461] 29. Mente J, Leo M, Panagidis D, Saure D, Pfefferle T. Treatment outcome of mineral trioxide aggregate: repair of root perforations-long-term results. J Endod. 2014 Jun; 40(6):790–6. [PubMed: 24862705] 30. Main C, Mirzayan N, Shabahang S, Torabinejad M. Repair of root perforations using mineral trioxide aggregate: a long-term study. J Endod. 2004 Feb; 30(2):80–3. [PubMed: 14977301] 31. Chong, BS. Managing endodontic failure in practice. Chicago: Quintessence Publishing Co., Ltd; 2004. p. 123-47. 32. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod. 2006 Jul; 32(7):601–23. [PubMed: 16793466]
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Biographies
Peter Z Tawil, DMD, MS, FRCD(C), Dip. ABE
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Dr. Peter Zahi Tawil started out his college career in Mechanical Engineering at McGill University in Montreal. He then pursued his studies in Dentistry at the Université de Montréal where he received his DMD in 2004. He continued his studies at the University of Rochester where he completed his degree in Advanced Education in General Dentistry. In 2008 he completed his specialty training in Endodontics at the University of North Carolina at Chapel Hill, graduating with a Masters in Endodontics. After completing his studies in Chapel Hill, Dr. Tawil worked as a specialist in private practice in Montreal while serving as an adjunct faculty member at McGill University. Dr. Tawil serves as a speaker for the American Association of Endodontists and has lectured nationally and internationally. He’s currently teaches full time as the Jacob and Charlotte Freedland Term Professor at the University of North Carolina at Chapel Hill. Furthermore, he’s a Fellow of the Royal College of Dentists of Canada and a Diplomate of the American Board of Endodontics.
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Derek J. Duggan, DDS, MS, Dip. ABE
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Dr. Derek Duggan received his dental degree from Trinity College Dublin in 2001. Following 3 years of private practice in both London and Dublin, Dr. Duggan completed a 1 year hospital residency at the Dublin Dental Hospital. He received his Masters in Endodontics from the University of North Carolina in 2008. He then worked for 1 year in a specialist private practice in Dublin. Dr. Duggan joined the Endodontic Department at UNC School of Dentistry in 2009, and is currently the preclinical endodontic course director. As a result of his stewardship, student’s learning experience has been greatly enhanced through short technique videos developed specifically for this course at UNC. Self paced learning is another distinguishing characteristic of this preclinical course. Dr. Duggan has hosted handson courses with colleagues at UNC for several years, including a number of interdepartmental CE courses. He is a Diplomate of the American Board of Endodontists, and continues to enhance his skills by actively engaging in both continuing education as well as interacting with his peers on a national and international level.
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Johnah C. Galicia, DMD, MS, PhD
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Dr. Johnah Galicia received his Masters in Endodontics degree from the University of North Carolina in 2014 as an American Association of Endodontists Foundation Educator Fellow. Prior to that, Dr. Galicia was a postdoctoral fellow at the School of Dentistry of the University of Pennsylvania and of the University of Louisville. He earned a PhD in Oral Biology from Niigata University in Japan and a Diploma in Clinical Dentistry from the University of Rennes 1 in France. He was a general dentist and a faculty member of his dental school alma mater, the Manila Central University in the Philippines, before entering the PhD program. In addition to clinical and academic pursuits, research has been also an integral part of Dr. Galicia’s career. He has co-authored several peer-reviewed articles in reputable international scientific journals and has presented his research in international forums. He is currently an Assistant Professor at the Department of Endodontics of the University of the Pacific School of Dentistry where he also practices endodontics. He has served as a member of the Research and Scientific Affairs Committee of the American Association of Endodontists (AAE) and is presently involved with the Marketing Committee of the AAE Foundation.
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Fig 1.
Fig 1A. ProRoot MTA. Fig 1B. MTA-Angelus.
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Fig 2.
Fig 2A. Pre-operative radiograph. Fig 2B. MTA-Angelus placed in the apical third. Fig 2C. Postoperative radiograph.
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Fig 3A. Pre-operative radiograph showing the aggressive external root resorption and the thin dentinal walls. Fig 3B. Working length confirmation. Fig 3C. Post-operative radiograph. Fig 3D. one year follow up showing a healthy lamina dura and root development. Fig 3E. Three years follow up showing the continued root development.
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Fig 4.
Fig 4A. Calcium sulfate placed in the bony portion of the perforation. Fig 4B. MTAAngelus placed in the dentinal portion of the perforation.
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Fig 5A/5B. Pre-operative radiographs showing the mesial perforation. Fig 5C. MTA perforation repair done and calcium hydroxide medication placed in the canals. Fig 5D. Post-operative radiograph. Fig 5C/D. Two year follow-up radiographs showing the positive outcome.
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Fig 6A. Pre-operative radiograph. Fig 6B. 3mm root resection with methylene blue staining. Fig 6C. Retro-preparation with ultrasonic tip. Fig 6D. MTA-Angelus placed as a retrofilling. Fig 6E. Post-operative radiograph. Fig 6F. Six month follow-up.
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