The development of Mineral Trioxide Aggregate (MTA) material by Torabinejad in 19931, was truly a landmark event in dentistry and in endodontics in particular. This event dramatically increased the success rate of many cases that used to have high failure rates. The many advantages of MTA material enlarged its use markedly in different fields of dentistry, from which, endodontics was the largest field to take advantage of this material.
What is MTA?
MTA is a powder consisting of fine hydrophilic particles of tricalcium silicate, tricalcium aluminate, tricalcium oxide and silicate oxide. It also contains small amounts of other mineral oxides, which modify its chemical and physical properties2. Hydration of the powder results in formation of colloidal gel with a pH value equal to 12.5 that solidifies to form a strong impermeable hard solid barrier in approximately three to four hours.2 Bismuth oxide powder has been added to make the aggregate radio-opaque.
MTA has a pH of 12.5 after setting, similar to calcium hydroxide. This may impart some antimicrobial properties.3 The material has a low solubility and a radio-opacity slightly greater than that of dentin. Because it has low compressive strength2, it should not be placed in functional areas.
|» (Figure 1)
Clinical applications of MTA
MTA has shown potential as an endodontic material in several in vitro and in vivo studies.4-7 It was first recommended as a material for repair of root perforations.1 It was then widely used as a root-end filling material8,9 and for vital pulp therapy, including direct pulp capping and pulpotomy of immature teeth with vital pulps (apexogenesis).5,10 In addition, because of its sealing ability, it was also suggested as an apical barrier in the treatment of teeth with opened apices and necrotic pulps (apexification).11,12
Masuda et al.13 in 2005, examined MTA in vivo and concluded that MTA is biocompatible and does not produce any adverse effects on microcirculation in the connective tissue. Witherspoon et al.14 in 2006, stated that MTA may be useful as a substitute for calcium hydroxide in pulpotomy procedures.
Advantages of MTA
- High biocompatibility
- Highly alkaline pH (Bacteriostatic)
- Excellent sealing ability (Low marginal leakage)
- Low solubility
Disadvantages of MTA
- Difficult manipulation
- High cost
- Irreversible application
What’s so Unique About MTA?
Materials used to repair perforations, seal the retro-preparation in surgical endodontics, close open apices or to protect the pulp in direct pulp capping, are inevitably in contact with blood and other tissue fluids. This moisturizing effect may be an important factor that has major effects on the physical properties and sealing abilities of the restorative materials. MTA is however not affected by moisture or blood contamination: The presence or absence of blood seems not to affect the sealing ability of the mineral trioxide aggregate.
1) An Apexogenesis Case: A twelve-year-old girl attended the clinic with acute pulpitis affecting her lower 2nd molar. A radiograph showed that the molar’s roots were not fully formed (Fig. 2a). MTA was used as a direct pulp capping material after removal of the inflamed coronal pulp. An x-ray taken six months later revealed normal physiological formation of the apices (Fig. 2b).
2) An Apexification Case: An eleven-year-old boy attended the clinic complaining of pain in his upper central tooth. Radiographic examination revealed the presence of a periapical lesion surrounding an opened apex of an upper central incisor tooth (Fig. 3a). MTA was used in an orthograde mode to seal the apex. An x-ray taken 12 months later revealed almost complete healing of the lesion (Fig. 3b).
3) A Perforation Case: A 24 year old lady attended the clinic with pain and tenderness affecting her lower molar tooth. Radiographic examination revealed the presence of a lateral perforation caused by improper post placement (Fig. 4a). MTA was used to seal the perforation. A radiograph taken 6 months later revealed favorable healing (Fig. 4b).
(Figure 2 a): Extensive caries reaching the pulp in a lower 2nd molar with opened apices
|(Figure 2 b): Physiological formation of the apices after six months of MTA application
(Figure 3 a): Periapical lesion affecting a central incisor with an opened apex
(Figure 3 b): Excellent healing after MTA application
(Figure 4 a): Furcation defect related to a lateral perforation
(Figure 4 b): Excellent healing after 6 months of MTA application
The use of MTA changed dramatically the treatment plan and increased the success rate of many previously thought of as hopeless cases. MTA is an efficient and promising dental material that should be used routinely in the practice of endodontics.
1. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations J Endod 1993 Nov;19(11):541-4.
2. Torabinejad M, Hong CU, McDonald F, Pitt Ford TR. Physical and chemical properties of a new root-end filling material. J Endod 1995 Jul;21(7):349-53.
3. Torabinejad M, Hong CU, Pitt Ford TR, Kettering JD. Antibacterial effects of some root end filling materials. J Endod 1995 Aug;21(8):403-6.
4. Mitchell PJ, Pitt Ford TR, Torabinejad M, McDonald F. Osteoblast biocompatibility of mineral trioxide aggregate. Biomaterials 1999 Jan;20(2):167-73.
5. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod 1999 Mar;25(3):197-205.
6. Moretton TR, Brown CE Jr, Legan JJ, Kafrawy AH. Tissue reactions after subcutaneous and intraosseous implantation of mineral trioxide aggregate and ethoxybenzoic acid cement. J Biomed Mater Res 2000 Dec 5;52(3):528-33.
7. Schmitt D, Lee J, Bogen G. Multifaceted use of ProRoot MTA root canal repair material. Pediatr Dent 2001 Jul-Aug;23(4):326-30.
8. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endod 1993 Dec;19(12):591-5.
9. Aqrabawi J. Sealing ability of amalgam, super EBA cement, and MTA when used as retrograde filling materials. Br Dent J 2000 Mar 11;188(5):266-8.
10. Abedi HR, Ingle JI. Mineral trioxide aggregate: a review of a new cement. J Calif Dent Assoc 1995 Dec;23(12):36-9.
11. Shabahang S, Torabinejad M. Treatment of teeth with open apices using mineral trioxide aggregate Pract Periodontics Aesthet Dent 2000 Apr;12(3):315-20; quiz 322.
12. 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; quiz 462.
13. Masuda YM, Wang X, Hossain M, Unno A, Jayawardena JA, Saito K et al. Evaluation of biocompatibility of mineral trioxide aggregate with an improved rabbit ear chamber. J Oral Rehabil 2005 Feb;32(2):145-50.
14. Witherspoon DE, Small JC, Harris GZ. Mineral trioxide aggregate pulpotomies: a case series outcomes assessment. J Am Dent Assoc 2006 May;137(5):610-8.