Orthograde Root Filling of an Immature Nonvital Tooth Using MTA

Mineral trioxide aggregate (MTA) has a variety of potential uses, including as a root canal obturating material. Studies have demonstrated encouraging regeneration of periradicular tissues, such as periodontal ligament, bone, and cementum, when MTA was used in endodontic procedures.1-3 There are also several reports of its superior biocompatibility with periodontal tissues,4,5 excellent sealing ability in the presence of moisture,6,7 and appropriate mechanical properties as apical sealing material.8
These encouraging outcomes from in vivo and in vitro studies have prompted many clinicians to consider the use of MTA as a root-end filling material and as a material suitable for repairing perforations and performing apexification.1-3 MTA has been used for the repair of lateral and furcation perforations and for the apexification of immature roots instead of Ca(OH)2.
MTA has an ability to facilitate normal periradicular architecture by inducing hard-tissue barriers.3 Formation of cementum surrounding MTA was observed even after extrusion of MTA into a furcation.9 On the basis of these findings, MTA may be an appropriate material for sealing immature root canals with open apices that could otherwise impose technical challenges in obtaining adequate obturation. A successful prognosis from conservative, nonsurgical treatment with MTA for such difficult cases can be of great benefit to the patient. The following case report demonstrates the use of MTA as an obturating material to promote periapical healing of a maxillary central incisor with an open apex due to a previous traumatic injury.

CASE REPORT

Figure 1. Preoperative radiograph showing an immature tooth with a wide open apex and a radiolucent area in proximity of the apex.	Figure 2. Radiograph taken with a gutta-percha point placed butt to tip to determine working length.
Figure 3. Final radiograph immediately following treatment.	Figure 4. Radiograph taken at 1 year postoperatively.

An 11-year-old male patient presented with a mild swelling at the apical region of his maxillary left central incisor. Radiographic examination revealed an immature tooth with a wide open apex and a radiolucent area in proximity of the apex of the tooth (Figure 1). Local anesthesia was obtained by labial infiltration using lidocaine with 1:100,000 epinephrine. After preparing an endodontic access opening, a No. 60 gutta-percha point was placed in a butt-to-tip direction, and a periapical radiograph was taken to determine the working length (Figure 2). The root canal was lightly cleaned with a hand file under irrigation with 1.3% NaOCl. The root canal was then dried with sterile paper points. Next, calcium hydroxide was prepared to a creamy consistency and placed in the root canal. The access opening was temporized, and the patient was then dismissed and instructed to return in 2 weeks.
When the patient returned in 2 weeks, the calcium hydroxide dressing was removed by hand instrumentation, and irrigation was done with 1.3% NaOCl and 17% EDTA. The root canal was then dried with sterilized paper points. A thick mixture of MTA was then prepared and applied to the apical portion of the canal using a small plugger and the back end of sterilized paper points. Finally, the access opening was permanently sealed with a bonded composite resin restoration (Figure 3).
The clinical follow-up at one year showed the patient functioning well with no reportable clinical symptoms and an absence of any sinus tract formation. The radiographic follow-up at one year (Figure 4) showed complete healing of the periapical radiolucency and a regeneration of the periradicular tissue.

DISCUSSION

Incomplete root development caused by trauma, caries, or other pulpal pathosis requires special attention and treatment. In such cases, the canal remains large with thin and fragile walls, and the apex architecture remains divergent. These features make instrumentation of the canal very difficult and hinder the formation of an adequate apical stop. As a result, it is imperative to create an artificial apical barrier or to induce the closure of the apical foramen with calcified tissue in order to allow for condensation of the root filling material and to create an adequate apical seal. The goal of the procedure is to limit bacterial infection and to create an environment conducive to the production of a hard-tissue-like or apical plug to prevent extrusion of root canal filling materials. Calcium hydroxide has become the material of choice for this treatment.10-12
A recent prospective clinical study showed that the mean time necessary for the formation of an apical barrier with this technique is more than 12 months.12 However, one must keep in mind that with the extended use of calcium hydroxide, the risk of tooth fracture increases.13 Other alternatives for the treatment of (nonvital) open-apex teeth include the creation of an artificial stop (apexification) in the apical area against which to condense gutta-percha14 or to fill the entire root canal with MTA.15
To date, only 2 in vitro studies16,17 and a single case report exist regarding the use of MTA as an orthograde root filling material in permanent teeth. Hayashi, et al15 reported 2 mandibular incisors filled with MTA. After 2 years, both teeth were clinically asymptomatic, and radiographic examination showed the dramatic regeneration of periradicular tissues. These findings are in agreement with the case described above.

CONCLUSION

So far, MTA has been shown to be a very effective root filling material in immature, open-apex teeth to promote the regeneration of apical tissue and to resolve clinical symptoms.

References

Dr. Mohammadi is an assistant professor in the Department of Endodontics at Shahid Sadoughi University of Medical Sciences in Yazd, Iran. He can be reached at mohammadi_zahed@yahoo.com.