Usage of white mineral trioxide aggregate in a non-vital primary molar with no permanent successor

Authors


Dr Emine Sen Tunc
Ondokuz Mayis University
Faculty of Dentistry
Department of Paediatric Dentistry
55139 Samsun
Turkey
Email: sentunc@yahoo.com

Abstract

The aim of this study was to present the treatment and long-term follow-up of a case in which white mineral trioxide aggregate (WMTA) was used in the pulpectomy of a non-vital primary molar with no permanent successor.

The physiological, aesthetic and functional consequences of treating primary teeth without permanent successors makes this a unique challenge. In the present case, WMTA was used in the pulpectomy of a primary molar with no permanent successor in an 8-year-old child. The treatment was considered successful. Follow-up examinations showed that root resorption in the mesial root surface, with no infra-occlusion or ankylosis 36 months after treatment.

WMTA may be considered as an alternative pulpectomy material for non-vital primary teeth with no permanent successors, although long-term clinical studies are still needed.

Abbreviations and acronyms:
MTA

mineral trioxide aggregate

WMTA

white mineral trioxide aggregate

Introduction

Hypodontia, the congenital absence of one or more teeth, is one of the most common dental polymorphisms to occur in humans.1,2 Hypodontia is classified according to the severity of the condition, with the term “mild-to-moderate hypodontia” used to denote the absence of between two and five teeth and “severe hypodontia” (oligodontia) to denote the absence of six or more teeth.1 The frequency of missing teeth varies among different populations, and it is generally accepted that the mandibular second premolar is the most common congenitally missing tooth (excluding the third molars).3,4 Hypodontia is often associated with retained and infra-occluded primary molars.5

Treatment of retained primary molars with no premolar successors presents a challenge for paediatric dentists, prosthodontists and orthodontists in terms of managing the missing second premolar successor.6 There are two main strategies used today; either extracting the primary second molar, or maintaining it for as long as possible and then seeking a prosthetic solution.7–9 In some cases, when the decision is made to retain the pulpally involved primary tooth, pulpotomy or pulpectomy may be indicated.10,11

In the conventional pulpectomy of a pulpally involved primary tooth with a missing permanent successor, the canals are filled with gutta-percha following reconstruction of the crown.12 However, there are inherent limitations involved in preparing curved, fragile primary molar roots to a proper master apical file size, and it may be difficult to achieve adequate obturation. A recent study recommended the use of mineral trioxide aggregate (MTA) for canal obturation in retained primary teeth. However, no long-term results were reported.10

MTA is an aggregate of fine hydrophilic particles that hardens on contact with water.13 It is comprised of 75% Portland cement, 20% bismuth oxide and 5% gypsum by weight, and while the initial compound was grey in colour, a white mineral trioxide aggregate (WMTA) has recently become available as well.14,15 This colour change has broadened the indications for MTA, enabling its application in anterior teeth. Originally developed for use in endodontics for the repair of root perforations,16 MTA was subsequently recommended for use as a root-end filling material.17 It has also been used in vital pulp therapy18,19 and as an apical barrier in the treatment of immature teeth with non-vital pulp and open apices.20 Potential uses of MTA in other dental and medical procedures are continually being explored.

This case report documents the treatment and long-term follow-up of a pulpectomy performed using WMTA on a non-vital primary molar with no permanent successor.

Case description

A healthy 8-year-old boy was referred to the paediatric dental clinic with the complaint of a toothache in the mandibular left molar region. Clinical examination showed the mandibular left second primary molar (75) to be slightly symptomatic to percussion, and a sinus tract was observed and traced to the tooth apex. Radiographic examination revealed gross caries in the mandibular left second primary molar and absence of the successional premolar (Fig 1). It was noted that agenesis of the mandibular left second premolar was unilateral. Based upon clinical and radiographic examination, a diagnosis for the 75 was made of pulp necrosis and chronic apical abscess with a sinus tract and no evidence of ankylosis or infra-occlusion. According to the patient’s mother, there was no family history of tooth agenesis.

Figure 1.

 Initial periapical radiograph shows extensive caries and enlargement of the periodontal ligament in the 75 and absence of the premolar successor.

An orthodontic examination was conducted, and an initial treatment plan was developed that aimed to avoid any future malocclusion by maintenance of the 75 for as long as possible, after which time an implant replacement would be inserted. Accordingly, the decision was made to treat the 75 by pulpectomy using WMTA (ProRoot, Dentsply, Tulsa Dental, OK, USA). The treatment objectives and alternatives were explained to the patient and his parents, who provided their written consent prior to treatment.

A regional anaesthetic was administered to block the buccal, lingual and inferior alveolar nerves, and the tooth was isolated with a rubber dam. A No. 245 bur (Dentsply Maillefer, Tulsa, OK, USA) in a high-speed handpiece was used for coronal access, and coronal pulp was removed with a round, spoon-shaped excavator. A No. 15 K-File was used to determine the working length of the canals (15 mm), which were prepared up to a No. 35 K-File at 14 mm using a step-back technique. Canals were irrigated with 2.5% sodium hypochlorite (NaOCl) and dried with sterile paper points. Calcium hydroxide (Kalsin, Aktu Tic, İzmir, Turkey) was placed in the canals using a lentulo spiral, and a temporary coronal seal was made with glass ionomer cement (Fuji IX, GC Corporation, Japan). After one month, the sinus tract had disappeared, and the patient was free of symptoms. The calcium hydroxide was removed by repeated rinsing with 2.5% NaOCl, followed by rinsing with sterile water. The canals were dried with sterile paper points, and a WMTA mixture was prepared using sterile water according to the manufacturer’s instructions. The WMTA mixture was placed in the canals with a lentulo spiral and compacted using paper points. The adaptation was checked radiographically, a cotton pellet moistened with sterile water was placed in the pulp chamber, and the access cavity was closed with glass ionomer cement. After three days, the glass ionomer cement and cotton pellet were removed, and the set of the WMTA was gently tested. The cavity was then restored again with glass ionomer cement and a stainless steel crown (3M Dental Products, USA) (Fig 2).

Figure 2.

 Immediate postoperative radiograph of the tooth treated with WMTA.

Regular follow-up appointments were conducted at six-month intervals. At 36-months of follow-up, the patient had no clinical signs or symptoms, and radiographic examination showed root resorption in the mesial root surface. The tooth was well-functioning, and no infra-occlusion or ankylosis was detected (Fig 3).

Figure 3.

 36-month follow-up periapical radiograph shows root resorption in the mesial root surface.

Discussion

Treatment options for congenitally missing mandibular second premolars vary according to the patient’s age, the development stage of adjacent teeth and the root resorption and infra-occlusion of the primary predecessor.7,9 Options include maintaining the primary tooth, extracting the primary tooth and allowing the space to close spontaneously, implant replacement, auto-transplantation, prosthetic replacement and orthodontic space closure.7,9

In growing patients, implants are contraindicated, as they impede the normal alveolar growth process.21 Age is also an issue with regard to conventional fixed partial dentures, since preparation of the abutment teeth may need to be delayed due to pulp size in young patients, and lengthy space maintenance may be necessary.7,9 Auto-transplantation of a third molar or another premolar is a viable option, if a suitable donor tooth is available,7,9 although the need for surgical intervention is a disadvantage.22 Extraction and spontaneous space closure is a conservative treatment option, but the timing of the extraction is critical, as early removal of the second primary molar can cause a series of changes in the dental arches, including reduction in arch length, inclination of adjacent teeth, alveolar bone resorption and extrusion of the antagonist tooth. In such cases, future malocclusion may be avoided by maintaining the primary molar.23,24

In the present case, the decision to maintain the 75 for as long as possible before inserting an implant replacement was based on the patient’s age, the lack of any malocclusion or arch-length deficiency, and the unilateral agenesis of the mandibular left second premolar. For this reason, a WMTA pulpectomy was performed, and regular follow-up appointments were scheduled to control for pulpal pathology, ankylosis and infra-occlusion.

Conventionally resorbable pastes such as zinc oxide-eugenol, iodoform and calcium hydroxide can be used for primary teeth pulpectomies. In the case of primary teeth with no permanent successors, pulpectomy treatment is performed in the same manner as with permanent teeth.12 MTA has been recommended as a root-canal filling material in pulpectomies of permanent teeth.25,26 Although obturation with gutta-percha has been shown to provide a better apical seal than MTA,27 WMTA was selected as a root-filling material in the present case because of MTA’s biocompatibility28,29 and its role in enhancing regeneration of periradicular tissue,30 and because of reported complications in gutta-percha pulpectomies related to inherent properties of primary molars.10

Optimal dental treatment planning requires an accurate assessment of the outcome of any required endodontic treatment.31 Studies on endodontic prognosis have addressed a wide range of factors in an attempt to accurately forecast the course of endodontic treatment outcome.32–35 These factors include pulpal and periapical diagnosis,32 residual pulp space infection,32,33 level of obturation,32 procedural iatrogens,34 and presence and quality of the permanent restoration.35 In the present case, the 75 had been retained for up to 36 months post-therapy without clinical signs or symptoms of obvious endodontic failure or premature exfoliation. After 36 months of follow-up, radiographic examination showed root resorption in the mesial root surface. However, it is difficult to say this finding is entirely a physiological root resorption; it could be physiological and/or pathologic root resorption. It was thought that root resorption in this case could be related to the above-mentioned factors, especially apical periodontitis. The presence of pre-operative root canal infection (apical periodontitis) was recently defined as a key confounding factor in endodontic treatment outcome.36 It often develops without giving any subjective symptoms. Physiological root resorption may be accelerated or delayed by local factors such as mechanical-occlusal trauma and pathologic processes occurring in the tooth and surroundings tissues.37 In the present case, treatment prognosis may be affected by root resorption. If the root resorption will progress agressively, different treatments such as a space maintainer can be applied.

Conclusions

WMTA may be considered as an alternative pulpectomy material for non-vital primary teeth with no permanent successors although long-term clinical studies are still required.

Ancillary