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Inside Dentistry
January 2020
Volume 16, Issue 1
Peer-Reviewed

Primary Molar Pulpotomy

ZOE and MTA offer potentially less toxic alternatives to formocresol

Theodore P. Croll, DDS | Constance M. Killian, DMD | Rachel L. Bresler, DMD

In 1991, Yacobi and colleagues wrote about how primary molar pulpotomy methods and materials were "evolving."1 One year later, Croll and Killian described a primary molar pulpotomy technique that used a thick mixture of zinc oxide powder and eugenol (ZOE) as the pulp space filling material, which was restored with a preformed stainless steel crown.2 That technique was developed by modifying the classic formocresol pulpotomy technique at the suggestion of Kaare Langeland, DDS, a professor of endodontics who cited toxicology studies regarding formocresol and suggested that formocresol pulpotomies might succeed despite the use of formocresol, not because of it (K Langeland, DDS, oral communication, 1976). If needed, ferric sulfate can be used as a hemostatic agent. Others have studied the use of ZOE as a pulpotomy medicament and pulp space filling material and reported success with the method.3,4

Another alternative, mineral trioxide aggregate (MTA), a medical version of Portland cement, has emerged as an important endodontic filling material5 and become one of the most frequently used materials for primary molar pulpotomies. Lin and colleagues performed a systematic review and network meta-analysis, and they reported that their findings "showed that MTA is the first choice for primary molar pulpotomies."6

This article presents three primary molar pulpotomy/stainless steel crown procedures in three children. One child was treated using ZOE as the pulp space filling material, and the other two were treated using MTA.

Case Report 1

A 39-month-old girl was brought in by her mother to receive a second opinion regarding treatment for a severe occlusal caries lesion on her mandibular right primary second molar (Figure 1). The patient's mother supplied a recent panoramic radiograph that had been recorded by the girl's previous pediatric dentistry specialist (Figure 2). There were no other caries lesions, and all of the other head, neck, and intraoral findings were unremarkable. At issue was the previous pediatric dentistry specialist's recommendation for hospitalization and general anesthesia to perform a pulpotomy/stainless steel crown treatment. The patient was shy but cooperative and displayed no obvious signs of anxiety during the examination; therefore, both the patient and her mother were shown photographs of a young patient receiving chairside treatment with a nitrous oxide/oxygen nasal mask in place, as well as earphones playing music, and the procedure was completely explained. Consent for treatment was obtained from the mother, and the child was appointed for the next day.

Once the child was seated, a nasal mask was placed, and a 20% nitrous oxide/80% oxygen flow was started. Earphones were supplied so that the patient could listen to children's music playing on a disk player. The region of the right mandibular second molar was anesthetized via infiltration of three-fourths of a carpule of articaine hydrochloride 4% with 1:200,000 parts epinephrine. After placement of the rubber dam using the slit-dam method, access to the lesion was achieved with a water-cooled high-speed cylindrical diamond bur (Figure 3). Access confirmed that the caries infection had spread into the pulp chamber. The carious dentin was debrided, and the pulp tissue in the chamber was amputated to the level of the root canal orifices with a sterile slow-speed No. 6 round bur. Bleeding from the root canals confirmed that the pulp tissue in the canals was still vital. A water-moistened cotton pellet was placed, compressed with a ball burnisher, and left in place for a few minutes, achieving hemostasis without the need for ferric sulfate or any other hemostatic agent. Next, a thick mixture of ZOE paste was blended with a spatula and compressed into the pulp chamber, and the excess was cleared away (Figure 4).2 The orthodontic band pictured in Figure 4 was placed to stabilize the rubber dam retainer. After placement of the ZOE paste, a resin-modified glass ionomer was mixed and injected over the ZOE-filled chamber then light cured prior to preparation for a stainless steel crown (Figure 5).

After 4 years and 8 months in the care of another dentist, the child returned for the restoration of a maxillary permanent first molar, which had an occlusal caries lesion that required a stratified resin-modified glass ionomer/resin-based composite repair.7 It was evident that the mandibular primary second molar pulpotomy/crown procedure had been successful (Figure 6 and Figure 7); however, due to advanced radicular resorption, impending eruption of the second premolar, and inflammatory gingival changes around the crown, this primary molar was extracted and then photographed after an infiltration injection of local anesthetic (Figure 8).

Case Report 2

A 9-year-old boy was referred by a family dentist for the treatment of an extensive occlusal caries lesion in his mandibular right primary second molar (Figure 9). There was also a caries lesion on the adjacent primary first molar and a large distal caries lesion on the maxillary right primary first molar. The radiograph that was taken suggested carious pulp exposure (Figure 10), so consent was obtained from the parent for a pulpotomy/stainless steel crown procedure for the mandibular right primary second molar with resin-based composite restoration of the adjacent primary first molar.

The patient was cooperative for the administration of local anesthetic, which was accomplished using three-fourths of a carpule of articaine hydrochloride 4% with 1:200,000 parts epinephrine. The rubber dam was placed using the slit-dam method (Figure 11), and from this point forward, the procedure performed was identical to that of Case Report 1 with the exception of the chamber filling material and restorative material used. A water-cooled cylindrical diamond bur was used to debride the carious substance and access the pulp chamber (Figure 12), and hemostasis was achieved with a sterile water-moistened cotton pellet that was compressed with pressure into the pulp chamber and then removed after a few minutes (Figure 13 and Figure 14). Next, a thick mixture of pure MTA (NeoMTA®, NuSmile) was blended with a spatula and compressed into the pulp chamber using a large amalgam condenser (Figure 15). Once hardening of the material commenced, the excess was cut away with a cylindrical diamond bur, and the adjacent primary first molar was prepared for a disto-occlusal restoration (Figure 16). Without the use of a matrix strip, a bioactive composite (ACTIVA BioACTIVE-RESTORATIVE, Pulpdent) was injected into both preparations and then light cured (Figure 17 and Figure 18). After curing, a 5% fluoride varnish was painted liberally on the mesial surface of the adjacent permanent first molar. The disto-occlusal restoration of the primary first molar was cut to contour, and after replacing the rubber dam retainer onto the permanent molar, a standard preparation for a stainless steel crown was completed for the primary second molar (Figure 19 and Figure 20).8 A stainless steel crown form was selected, trimmed, contoured, crimped, finished, polished in the usual manner, and then cemented with a resin-modified glass-ionomer luting cement.8 Any excess extruded cement was removed with a Hollenback carver (Figure 21), and knotted dental tape was used to clear the excess cement from the interproximal areas. The maxillary right primary first molar was restored at a subsequent appointment. A photograph and radiograph show the primary second molar crown 22 months after cementation (Figure 22 and Figure 23). The patient was lost to follow-up after 22 months because the patient's parents transferred his care to the original referring dentist.

Case Report 3

An 8-year-old boy was referred by his family dentist for extraction of his mandibular left primary second molar (with consideration of a space maintainer for the subsequent extraction site) and a disto-occlusal restoration of the approximating primary first molar (Figure 24 and Figure 25). Instead, the possibility of conserving the tooth with a pulpotomy/crown procedure was explained to the parents, and they consented to the proposed treatment.

Using the same approach that was described in Case Report 2, local anesthesia was established, the rubber dam was attached to the permanent first molar, the MTA pulpotomy/stainless steel crown procedure was completed, and the primary first molar was restored (Figure 26). As before, hemostasis was achieved with no other agent except for a water-moistened cotton pellet compressed into the preparation after pulp amputation, then MTA chamber filling, resin-modified glass-ionomer filling, and stainless steel crown restoration followed. The restored molar is shown clinically and radiographically 33 months after treatment (Figure 27 and Figure 28). At that time, the primary first molar and primary second molar (Figure 29) were extracted for orthodontic considerations.

Discussion

The use of a rubber dam for primary molar pulpotomy is essential. A rubber dam provides patient safety and comfort during the procedure, the maintenance of an ideal operative field that facilitates both ease of treatment and shorter treatment time, and also assists in basic behavior management.

If the pulp chamber is entered and a completely devitalized pulp is encountered with no bleeding, it is likely that either pulpectomy or tooth extraction should be considered. When indicated, extraction followed by space maintenance is preferred, based on the complexity of the primary molar root canal systems and the potential for continuing infection, which could possibly affect the surrounding alveolar bone and underlying developing premolar.

In each of these three cases, there was no difficulty achieving hemostasis after the affected pulp tissue was removed. Sometimes, however, bleeding persists. In such cases, the dentist can use a sterile slow-speed round bur to amputate more of the pulp tissue at the chamber/root canal junction. After that, a cotton pellet dipped in ferric sulfate and squeezed into a cotton roll can be compressed over the pulp stumps and retained for 30 to 60 seconds to achieve hemostasis. This can be repeated if additional bleeding ensues. Occasionally, this ferric sulfate hemostatic measure is referred to as a "ferric sulfate pulpotomy," but the chemical simply serves to help stop the bleeding; therefore, the use of the term "ZOE pulpotomy" or "MTA pulpotomy" is more descriptive of the procedure.

About the Authors

Theodore P. Croll, DDS
Clinical Professor
Pediatric Dentistry
Case Western Reserve University
School of Dental Medicine
Cleveland, Ohio

Cavity Busters
Doylestown, Pennsylvania

Constance M. Killian, DMD
Adjunct Associate Professor Pediatric Dentistry
University of Pennsylvania School of Dental Medicine
Philadelphia, Pennsylvania

Private Practice
Doylestown, Pennsylvania

Rachel L. Bresler, DMD
Adjunct Clinical Instructor
Pediatric Dentistry
Temple University
Kornberg School of Dentistry
Philadelphia, Pennsylvania

Cavity Busters
Philadelphia, Pennsylvania

References

1. Yacobi R, Kenny DJ, Judd PL, et al. Evolving primary pulp therapy techniques. J Am Dent Assoc. 1991;122 (2):83-85.

2. Croll TP, Killian CM. Zinc oxide-eugenol pulpotomy and stainless steel crown restoration of a primary molar. Quintessence Int. 1992;23(6):383-388.

3. Gonzalez-Lara A, Ruiz-Rodriguez MS, Pierdant-Perez M, et al. Zinc oxide-eugenol pulpotomy in primary teeth: a 24-month follow-up. J Clin Pediatr Dent. 2016;40(2):107-112.

4. Hui-Derksen EK, Chen CF, Majewski R, et al. Retrospective record review: reinforced zinc oxide-eugenol pulpotomy: a retrospective study. Pediatr Dent. 2013;35(1):43-46.

5. Camilleri J, ed. Mineral Trioxide Aggregate in Dentistry. 1st ed. Berlin, Germany: Springer-Verlag; 2014.

6. Lin PY, Chen HS, Wang YH, et al. Primary molar pulpotomy: a systematic review and network meta-analysis. J Dent. 2014;42(9):1060-1077.

7. Croll TP, Cavanaugh RR. Posterior resin-based composite restorations: a second opinion. J Esthet Restor Dent. 2002;14(5):303-312.

8. Croll TP. Preformed posterior stainless steel crowns: an update. Compend Contin Educ Dent. 1999;20(2):89-92,94-96, 98-100 passim; quiz 106.

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