Treatment Protocol Using a New MTA Material

INTRODUCTION
Throughout the world, dental trauma is a significant health problem affecting children and adolescents.¹ Twenty percent to 30% of 12-year-old children may develop damaged dentition due to the dental trauma they are currently experiencing.² Traumatic injuries of the developing dentition can, at times, be very challenging to treat and may lead to premature loss of permanent teeth. When Hertwig’s root sheath is damaged, or an injury causes pulp necrosis, the development of the root suffers. This may cause thinning of dentinal canal walls, which may weaken the tooth and leave it more susceptible to fracture.³ Immature teeth have blunt ends and wide-open apices, making an optimal apical seal difficult to achieve.^4,5

As a result of the rare occurrence of intrusion in permanent teeth (up to 1.9% of the cases²), there is a lack of reports documenting the epidemiological information, clinical radiographic appearance, and knowledge about the treatment of these injuries.⁶ When immature permanent teeth are injured, the dental structure, periodontium, and pulpal tissues are also damaged. Though these injuries can heal on their own, the healing process often includes root resorption, pulp canal obliteration, and necrosis.⁷ The traditional treatment approach consists of chemical-mechanical disinfection of the immature root canal system, followed by a long-term dressing of calcium hydroxide (Ca[OH]₂) with the objective to stimulate the formation of a hard-tissue biological barrier at the root apex, a procedure called apexification. Although apexification has high success rates, inherent disadvantages exist—especially concerning the length of time for induction of coronal or apical hard-tissue barriers. When pulp capping,⁸ the induction of coronal or apical hard-tissue barriers usually takes 2 to 3 months.^9,10 With apexification procedures, it can take 6 to 18 months, with an average of 9 months.¹¹ This amount of time can make it difficult to achieve patient compliance, as the patient may not agree to the number of appointments needed to complete the procedures. Such lengths of time, apart from delaying completion of treatment, also represent a risk of failure in patient compliance with subsequent appointments.

Brief Background on MTA
In 1993, a new endodontic material called mineral trioxide aggregate (MTA) was developed by Torabinejad et al^12,13 primarily for making a biocompatible material to seal accidental perforations of the root canal, among other applications. Subsequently, the material was shown to also be ideal as root-end filling material and a material for use in pulp capping and pulpotomy cases.¹³ Later, MTA found its way into the treatment of traumatized immature teeth (apexification), as some of the shortcomings of Ca(OH)₂ seemed to be overcome with the use of MTA.¹⁴

With the introduction of MTA repair material, significantly less clinical steps are needed to create the apical barrier, and the technique rapidly became very popular. The rationale is to establish a biocompatible apical barrier that would enable the root canal to be filled and restored. The success rate of MTA apical barrier techniques was reported to reach 94% ten years after the apical plug placement.¹⁵ Whilst advances with apical barrier techniques and bonded restorations go some way towards a better outcome, handling and delivering properties of commercially available MTA remains a challenge. In the conventional powder/water presentation, the sandy consistency that results from mixing and the need for amalgam carrier-based delivery devices add some difficulties to the use of this repair material in the apical third of immature open apices.

The aim of the present report is to describe and discuss the clinical and radiographic treatment outcome of immature traumatized maxillary central incisors following an apexification approach using a new MTA (MTAFlow [Ultradent Products]) performed as an apical bio-inductive material.

CASE REPORT
Diagnosis and Treatment Planning
An 11-year-old male was referred for evaluation and possible treatment of traumatic intrusion. The patient and mother reported that the permanent maxillary central incisors (teeth Nos. 8 and 9) were traumatized during a bike ride, and an emergency intervention was performed 2 weeks previously. Attempts to retrieve clinical data and the description of the procedure performed were tried with no success. The clinical exam revealed extensive enamel-dentine crown fractures associated with intrusion and rotation (Figure 1) caused by axial impact, with normal soft tissues. On a scale of zero to 3, the grade of teeth mobility was rated as zero to one. In the clinical tests, both incisors were tender to percussion and did not respond to the vitality cold testing (Hygenic Endo-Ice [Coltene]). Periapical radiographic examination showed the immature open apices and absence of radiolucent lesion in the apical area of the injured teeth and an atypical position of both elements, notably traumatic intrusion and rotation (Figure 2). The pulpal diagnosis was necrosis, and the apical diagnosis was asymptomatic apical periodontitis.

Clinical Protocol
Infiltration anesthesia (Septocaine [Septodont]) was administered, and a rubber dam (DermaDam [Ultradent Products]) was placed. The pulp chamber was accessed with a diamond bur (801 LD No. 14 [Brasseler USA]), and no bleeding from the canals (Nos. 8 and 9) was noticed. After the access cavity preparation, the working length was obtained. The canal content was chemically and mechanically cleaned by using the following: engine-driven endodontic instruments (Genius System [Ultradent Products]), sodium hypochlorite (NaOCl) at 3% viscous (ChlorCid V solution [Ultradent Products]) during the mechanical instrumentation, and 3% NaOCl (ChlorCid solution [Ultradent Products]) irrigation after each instrument use. The canal was dried with sterile paper point, and a premixed Ca(OH)₂ paste (Ultracal XS paste [Ultradent Products]) was placed to the working length using a size 29-gauge (g) cannula tip (NaviTip [Ultradent Products]). Cavit G (3M) was used as a temporary restoration (Figure 3).

After 2 weeks, the Ca(OH)₂ was removed by repeated rinsing with 3% NaOCl (ChlorCid solution), followed by rinsing with 20% citric-acid solution (20% Citric Acid [Ultradent Products]), and a final flush with sterile water. The canals were dried with capillary tips (Capillary Tip [Ultradent Products]) connected to an aspirator device. Under the operative microscopy (Global Surgical), the MTA repair cement mixture (MTAFlow) (Figure 4)—in a thin consistency mixing proportion, according to the manufacturer’s suggestion—was placed using a syringe (Clear Skini syringe [Ultradent Products]) and cannula tip (NaviTip, size 29-g) at approximately 2.0-mm short of the working length, aiming to create a 2.0- to 3.0-mm thick apical plug. After the positioning of the MTA apical plug, a periapical radiograph control (Figure 5) was done to check the correct placement of the cement. Next, a sterile cotton pellet was placed in the pulp chamber and the access cavity was closed with temporary restoration. After 48 hours, the temporary restoration and the cotton pellet were removed and the set of the MTA was gently tested. The rest of the canal was filled with thermoplastic gutta-percha (Obtura II [Obtura Spartan]) applied in association with a canal sealer (EndoREZ [Ultradent Products]). The teeth (Nos. 8 and 9) were coronally sealed with composite resin (Figure 6).

Figure 2. Radiographic image showing the maxillary incisors with traumatic intrusion (No. 8) and intrusion and rotation (No. 9). Incomplete root formation and open apices are shown.	Figure 3. Ultracal XS (Ultradent Products) calcium hydroxide premixed paste in place.

Figure 5. MTAFlow in place (apical plug).	Figure 6. Coronal seal (top) and reconstruction (bottom) of the crowns with composite.

The clinical follow ups at 12 (Figure 7) and 18 months (Figure 8) revealed adequate clinical function and an absence of clinical symptoms (voluntary and induced pain).

DISCUSSION
There is not a lot of published material about the prognosis or treatment for the intrusion of permanent teeth, as it is rare. But it is important to note that crown fractures associated with intrusions may lead to infection of the exposed dentin, culminating in pulp necrosis.¹⁶

Within the cases reported, passive or surgical repositioning to stabilize the teeth were rejected. The analysis of the radiographic images showed that between one half and two thirds of the roots were formed, and the repositioning could cause further injury to the traumatized periodontal ligament.

Although studies have demonstrated that Ca(OH)₂ has a high rate of success in cases of traumatized immature permanent teeth, one negative aspect of the handling of Ca(OH)₂ is the duration of the treatment, which is usually very long and depends on factors such as the size of the apical opening, the traumatic displacement of the tooth, and the repositioning methods used.

Figure 7. Follow-up radiograph at 12 months.	Figure 8. Follow-up radiograph at 18 months.

MTA is a relatively new material that is better known among specialists in endodontics because it was first introduced for surgical endodontic procedures (apicectomies and retrograde root-end fillings) and as a repair material in root perforations. MTA has been found to have an impressively high degree of biocompatibility. It is also known to provide a seal that is superior to any other material used in endo­dontics for the purposes of surgical or nonsurgical treatment. With the MTA apical plug technique, a 2-step obturation after short canal disinfection with Ca(OH)₂ could be performed. The MTA mixture created an artificial stop to the permanent obturation material. The great difficulty with MTA since its launch as a repair material has been its mixing and delivering properties. Torabinejad¹⁷ recommended carrying MTA to the root canal using an amalgam carrier and then condensing it with absorbent paper, which is difficult to perform depending on the caliber and anatomy of the root canals.

In the clinical cases reported, the new MTAFlow cement was used; the cement is a powder and liquid presentation that allows the mixing of very small particles of MTA powder with a water-gel liquid, resulting in a butter-like consistency. The suggested delivery system is a syringe and a 29-g cannula tip, allowing a controlled and accurate positioning of the material in the apical third of the canal. In one quick, single step, the operator can create the desired layer of material to define the apical plug. After positioning the MTA, the radiographic images confirmed the ideal position and thickness of the plug. To limit bacterial infection, a temporary Ca(OH)₂ dressing should be used before the MTA mixture.¹⁸

CLOSING COMMENTS
Though the prognosis is uncertain, the use of MTA for traumatized immature permanent teeth may allow longer tooth survival.¹⁶ Both clinical and radiography follow ups in the reported cases showed healing and new hard tissue formation in the apical area of affected teeth. The results are similar to another clinical report,¹⁷ where MTA was used as an apical plug in a central incisor with an open apex. Aesthetic, functional, and psychological conditions of the young patients could be preserved until a definitive prosthetic solution should be put in place.

References

1. Piovesan C, Abella C, Ardenghi TM. Child oral health-related quality of life and socioeconomic factors associated with traumatic dental injuries in schoolchildren. Oral Health Prev Dent. 2011;9:405-411.
2. Andreasen JO, Andreasen FM, Andersson L. Textbook and Color Atlas of Traumatic Injuries to the Teeth. 4th ed. Oxford, England: Blackwell Munksgaard; 2007.
3. Andreasen JO, Farik B, Munksgaard EC. Long-term calcium hydroxide as a root canal dressing may increase risk of root fracture. Dent Traumatol. 2002;18:134-137.
4. Rafter M. Apexification: a review. Dent Traumatol. 2005;21:1-8.
5. Walton RE, Torabinejad M. Principles and Practice of Endodontics. 3rd ed. Philadelphia, PA: Saunders; 2002:334-336.
6. Humphrey JM, Kenny DJ, Barrett EJ. Clinical outcomes for permanent incisor luxations in a pediatric population. I. Intrusions. Dent Traumatol. 2003;16:266-273.
7. Al-Badri S, Kinirons M, Cole B, et al. Factors affecting resorption in traumatically intruded permanent incisors in children. Dent Traumatol. 2002;18:73-76.
8. Olsson H, Petersson K, Rohlin M. Formation of a hard tissue barrier after pulp cappings in humans. A systematic review. Int Endod J. 2006;39:429-442.
9. Mackie IC, Bentley EM, Worthington HV. The closure of open apices in non-vital immature incisor teeth. Br Dent J. 1988;165:169-173.
10. Cvek M. Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study. Endod Dent Traumatol. 1992;8:45-55.
11. Kinirons MJ, Srinivasan V, Welbury RR, et al. A study in two centres of variations in the time of apical barrier detection and barrier position in nonvital immature permanent incisors. Int J Paediatr Dent. 2001;11:447-451.
12. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations. J Endod. 1993;19:541-544.
13. Torabinejad M, Parirokh M. Mineral trioxide aggregate: a comprehensive literature review—Part II: leakage and biocompatibility investigations. J Endod. 2010;36:190-202.
14. Shabahang S, Torabinejad M. Treatment of teeth with open apices using mineral trioxide aggregate. Pract Periodontics Aesthet Dent. 2000;12:315-320.
15. Pace R, Giuliani V, Nieri M, et al. Mineral trioxide aggregate as apical plug in teeth with necrotic pulp and immature apices: a 10-year case series. J Endod. 2014;40:1250-1254.
16. Oliveira TM, Sakai VT, Silva TC, et al. Mineral trioxide aggregate as an alternative treatment for intruded permanent teeth with root resorption and incomplete apex formation. Dent Traumatol. 2008;24:565-568.
17. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod. 1999;25:197-205.
18. Giuliani V, Baccetti T, Pace R, et al. The use of MTA in teeth with necrotic pulps and open apices. Dent Traumatol. 2002;18:217-221.

Additional Reading
Andreasen JO, Bakland LK, Matras RC, et al. Traumatic intrusion of permanent teeth. Part 1. An epidemiological study of 216 intruded permanent teeth. Dent Traumatol. 2006;22:83-89.
Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review—Part III: clinical applications, drawbacks, and mechanism of action. J Endod. 2010;36:400-413.
Wigler R, Kaufman AY, Lin S, et al. Revascularization: a treatment for permanent teeth with necrotic pulp and incomplete root development. J Endod. 2013;39:319-326.

Dr. Ramos graduated with a degree in dentistry from the State University of Londrina in Brazil (1987) and then received a scholarship to study in Japan. He finished his residency in endodontics at University of São Paulo (USP), Brazil (1990), where he also attended a program in endo­dontics and received a Master of Science degree (1993), then completed a PhD program in endodontics (1997)—the same year he published his first book. From 1995 to 2012, he worked as a professor of endodontics at the State University of Londrina, where he coordinated the endodontics sector. During this time, he published 3 books and wrote more than a dozen chapters for various endodontics books. All this was accomplished while he was in part-time private practice as an endodontic specialist from 1987 to 2012 Londrina. He was granted 3 international patents, which have brought different devices to the world marketplace that use these patented technologies. He is an international leader in endodontics—presenting lectures, hands-on workshops, and conferences worldwide each year. He can be reached via email at the address: carlos.ramos@ultradent.com.

Disclosure: Dr. Ramos is the Clinical Affairs Endo­dontics Manager and is the clinical advisor for endodontics for Ultradent Products, Inc.

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