Injured Pulps

Management of Traumatically Injured Pulps in Immature Teeth Using MTA

Leif K. Bakland, DDS

Copyright 2000 Journal of the California Dental Association.

Maintaining pulpal health during tooth development is an important goal in managing traumatic injuries in the immature dentition. The introduction of mineral trioxide aggregate has offered an improved method for pulp protection in such cases. This article describes a technique using MTA for vital pulp therapy on teeth with crown fractures that have resulted in pulp exposure.

Traumatic injuries to immature permanent teeth can have adverse effects on the entire dentition as well as on the individual teeth themselves. If pulp necrosis occurs in a tooth prior to complete root formation, the tooth may be lost due to subsequent fracture of the weak, underdeveloped root, resulting in a potential for orthodontic complications. Replacement of missing teeth in the developing dentition often presents complex treatment problems. The special concern for maintaining pulpal health during tooth development becomes an important goal in managing traumatic injuries in the immature dentition.¹

Efforts to manage pulpal injuries have until recently primarily involved the use of calcium hydroxide.² Successful results have been predictable as long as the pulp could be protected from bacterial invasion, mostly resulting from microleakage associated with the temporary or definitive restorations used. Calcium hydroxide is an effective antibacterial agent,³ but the effectiveness is limited because the material is neutralized by exposure to tissue fluids. After its pH value is reduced, it is no longer effective and bacteria can again grow in its presence. The use, however, of properly managed calcium hydroxide can provide an excellent service for an immature tooth with crown fracture. The technique has been described in many publications, including this journal.⁴

The introduction of a new dental material, mineral trioxide aggregate (Pro Root MTA, Tulsa Dental Products, Tulsa, Okla.), which has been investigated extensively for its ability to seal pathways of communication between the root canal system and the external tooth surface,^5,6 has offered an improved method for pulp protection.⁷ MTA’s advantages are related to its ability to effectively seal the material-tooth interface to prevent bacterial penetration and to its high level of biocompatibility.⁵ In contrast to calcium hydroxide, which deteriorates over time and gradually disintegrates, thereby leaving space for potential microleakage, MTA does not appear to change over time. Therefore, it preserves the protective cover over, for instance, developing reparative dentin,⁷ preventing bacterial invasion of the pulp.

The technique for managing a traumatic pulp exposure using MTA is in many ways similar to that used with calcium hydroxide,⁴ with some minor modifications as will be described for a tooth with crown fractures and pulpal exposure:

1. The tooth must be anesthetized and should be isolated with a rubber dam.
   
   
2. The tooth, fractured surface and wound area should be disinfected using a solution such as sodium hypochlorite.
   
   
3. A shallow pulpotomy is done to provide space for the MTA. A round diamond stone is used in a high speed handpiece with water irrigation to remove exposed pulp tissue to a depth of at least 2 mm into the pulp proper. Bleeding is allowed to stop (which usually takes two to three minutes) before MTA is placed directly onto the pulp wound. The presence of a small amount of blood in the wound area is not a contraindication to placing MTA; in fact, some moisture is required for the proper curing of the material.
   
   
4. Since access is not a problem when performing a shallow pulpotomy, the placement of MTA is not as difficult as it often can be when used for other purposes, such as repair of perforations. The mixture of MTA powder and liquid should be of a consistency that it can be carried from the mixing pad to the pulp wound using a dental instrument such as a spoon excavator. A small amount of MTA should be placed on the wound surface and gently tapped with a moist cotton pellet so that it covers the exposed pulp. Next, the entire access into the pulp should be filled in a similar manner using small amounts of MTA. Any excess moisture should be removed from the surface of the MTA using a dry cotton pellet.
   
   
5. The rubber dam can then be removed and the patient can be dismissed. Leaving the MTA exposed to saliva will allow it to cure. A minimum of six hours should be allowed for the material to adequately cure, but clinical experience indicates that waiting at least 24 hours is better. The tooth can then be restored with a definitive restoration.

Previous research^7,8 has shown that the pulp responds favorably to the protection provided by an MTA layer. The reparative dentin is consistently more uniform and thicker under MTA compared with calcium hydroxide. As has been convincingly demonstrated,⁹ the pulp can tolerate almost any dental material and produce new dentin as long as it can be protected against microleakage, a function that MTA appears to perform better than any material with which it has been compared.

The differences in the vital pulp therapy technique when MTA is used in place of calcium hydroxide are important to consider.

First, it is not important that the pulp wound bleeding be completely stopped prior to placing the MTA; in fact, the presence of a small amount of blood provides necessary moisture for curing of the material and has been shown to work as well as any other fluid.¹⁰

Second, since the MTA needs to cure prior to placement of a definitive restoration, it is necessary to schedule two appointments for this procedure: the first to perform the shallow pulpotomy and place the MTA on the pulp wound, and the second to complete the restoration after the material has cured. Future material development may be expected to result in a faster-curing MTA.

Third, it is not necessary to re-enter the pulpotomy site later to remove the pulp capping material, as has been recommended for calcium hydroxide pulpotomies.¹¹ MTA does not appear to deteriorate and disintegrate with time, thus space for microleakage does not develop as it does with calcium hydroxide.

In sumary, a technique using mineral trioxide aggregate for vital pulp therapy has been described for teeth that have been subjected to traumatic crown fractures resulting in pulp exposure (Figures 1 and 2). The technique is similar to that used with calcium hydroxide⁴ with some modifications. The recommended procedure is supported by evidence from animal research,^7,8 clinical experience⁵ and extensive application in similar clinical situations in which pathways between a tooth’s pulp and external surface need to be sealed.⁶

Author

Leif K. Bakland, DDS, is a professor in and chair of the Department of Endodontics at Loma Linda University School of Dentistry. He is also the school’s associate dean of advanced education.

References

1. Andreasen FM, Andreasen JO, Crown fractures. In, Andreasen JO, Andreasen FM, Textbook and Color Atlas of Traumatic Injuries to the Teeth, 3rd ed. Munksgaard, Copenhagen, 1993, p 219-56.

2. Cvek M, A clinical report on partial pulpotomy and capping with calcium hydroxide in permanent incisors with complicated crown fractures. J Endodon 4:232-7, 1978.

3. Sjögren U, Figdor D, et al, The antimicrobial effect of calcium hydroxide as a short-term intracanal dressing. Int Endodon J 24:119-25, 1991.

4. Bakland LK, Milledge T, Nation W, Treatment of crown fractures. J Cal Dent Assoc 24(2):45-50, 1996.

5. Torabinejad M, Chivian N, Clinical application of mineral trioxide aggregate. J Endodon 2:197-205, 1999.

6. Abedi HR, Ingle JI, Mineral trioxide aggregate: a review of a new cement. J Cal Dent Assoc 23(12):36-9, 1995.

7. Pitt Ford TR, Torabinejad M, et al, Mineral trioxide aggregate as a pulp capping material. J Am Dent Assoc 127:1491-4, 1996.

8. Junn D, Assessment of dentin bridge formation following pulp capping with mineral trioxide aggregate. Master’s thesis, Loma Linda University School of Dentistry, 2000.

9. Cox CF, Keall CL, et al, Biocompatibility of surface-sealed dental materials against exposed pulps. J Prosthet Dent 57:1-8, 1987.

10. Torabinejad M, Hong CU, Pitt Ford TR, Physical properties of a new root end filling material. J Endodon 21:349-53, 1995.

11. Cvek M, Endodontic management of traumatized teeth. In, Andreasen JO, Andreasen FM, Textbook and Color Atlas of Traumatic Injuries to the Teeth, 3rd ed. Munksgaard, Copenhagen, 1993, pp 517-86.

To request a printed copy of this article, please contact Leif K. Bakland, DDS, LLU School of Dentistry, Department of Endodontics, Loma Linda, CA 92350.

Legends

Figure 1A. Shallow pulpotomy using MTA. Pre-operative radiograph of maxillary right central incisor with traumatic pulp exposure, open apex, and no clinical symptoms.

Figure 1B. Shallow pulpotomy and capping the pulp with MTA.

Figure 1C. Twenty-eight-month postoperative radiograph showing closure of the apex of the tooth in Figure 1A and the left central incisor, which had a similar procedure 18 months prior to the taking of this radiograph (With permission, from Apaydin E, Handysides R, Odabashian N, MTA: A new endodontic material. LLU Dentistry, 11:16-9, 2000).

Figure 2A. Shallow pulpotomy followed by bonding of the fractured coronal crown segment in an 11-year-old boy. Pre-operative photo showing maxillary right central incisor with a horizontal fracture line in the cervical area (arrow). The palatal fracture line was subgingival making this case a crown-root fracture with pulp exposure. The coronal fragment was held in place by the palatal gingival attachment.

Figure 2B. Radiograph showing fracture line; note the large radicular pulp space indicating a less than fully formed root.

Figure 2C. Photo showing the tooth isolated with rubber dam, the coronal segment has been removed, and the MTA pulpotomy has been completed.

Figure 2D. Radiograph showing the tooth after the MTA pulptomy. After curing for six hours by exposure to saliva, the coronal fragment was bonded into place.

Figure 2E. Photograph after bonding the coronal segment to the remaining tooth.

Figure 2F. Radiograph showing the final result (Coronal bonding courtesy of Dr. Todd Milledge).