Filling lateral canals in a second maxillary premolar – two clinical case reports

Introduction

Knowledge of the internal anatomy of teeth is crucial for the success of endodontic treatment. This means having knowledge of the number of the roots, number of canals and their location, cross-sectional shapes, most frequent curvatures and variations of root canal system. Root canal treatment may fail if the root canal system is not fully identified and treated.

The maxillary second premolar is in 91.5% of cases a single-root tooth⁽¹⁾. It has a single canal in 51.8%⁽²⁾ of cases, therefore a high proportion will have two canals present. Canal exploration should be done keeping in mind the types of the Vertucci’s or Weine’s classification. The most simple and common classification was presented by F. Weine⁽³⁾:

• Type I – a single main canal from the pulp chamber to apical foramen.

• Type II – two separate canals, joining in the root as one, with one apical foramen.

• Type III – two separate canals starting from the pulp chamber and leaving the root by two apical foramina.

• Type IV – a single canal starting from the pulp chamber, dividing into two canals and leaving the root by two different apical foramina.

The majority of second premolars had a single canal and foramen at the apex.

The lateral canals are communication pathways between the main canal and the periodontal space. Relatively few case reports investigated the apical root anatomy of teeth. In these studies, accessory or lateral canals were found in three quarters of the specimens. On histological examination, even more lateral canals with many separate foramina were found, showing that mid-root and apical lateral canals are common.

These lateral canals with small arterioles and venules represent a collateral circulation, but they do not contribute to the pulp circulation. They are formed by the intertwining of periodontal vessels in Hertwig’s root sheath during the process of calcification. Also, they play as a “portal of exit” into the surrounding periodontal ligament space when the pulp becomes diseased⁽⁴⁾.

In case of pulpal pathosis, it is very important to seal the entire space of endodontic system, together with lateral and accessory canals, because that means a premise for the rapid healing of apical periodontitis⁽⁵⁾.

Clinical case reports

Case 1

A 36-year-old female patient presented to the dental office with spontaneous pain in tooth 15. The tooth had pain upon biting and percussion, without fistula, but a little swelling was presented. An objective exam revealed a non-vital tooth, with a loss of dental structure on the mesial surface of the tooth. The initial radiograph revealed an apical periodontitis (Figure 1 a, b, c). The diagnosis of acute apical abscess has been made.
 

At the first appointment, the tooth received an endodontic drainage, a rotary instrumentation until X2 (25.06) instrument and an inter-appointment treatment with calcium hydroxide.

In the second appointment, the tooth received rotary instrumentation with the Protaper Next (Dentsply Sirona) system was performed until X3 (30.06) instrument. After copious irrigation with 5.25% sodium hypochlorite and sonic agitation using the Endoactivator instrument (Dentsply Sirona), the canal was obturated using the continuous wave technique and AH Plus sealer (Dentsply Sirona). The presence of apical lateral canals is demonstrated by sealer extrusion. At the one-year recall, the lesion disappeared and the tooth was healed.

Case 2

A 46-year-old male patient presented to the dental office with spontaneous pain in tooth 25. The tooth had pain upon biting and percussion, without fistula or swelling. An objective exam revealed a non-vital tooth, with a metal-ceramic crown, part of a larger dental bridge. After the removal of the dental bridge, the initial radiograph revealed an incomplete root canal filling and an apical periodontitis (Figure 2 a, b). The diagnosis of acute apical periodontitis was made.
 

The tooth received a single-visit treatment, using in the beginning Protaper D1, D2 and D3 system for retreatment, without solvent. Then rotary instrumentation with the Protaper Next (Dentsply Sirona) system was performed until X3 (30.06) instrument. After copious irrigation with 5.25% sodium hypochlorite and sonic agitation using the Endoactivator instrument (Dentsply Sirona), the canal was obturated using the continuous wave technique and AH Plus sealer (Dentsply Sirona).

The presence of apical lateral canals is demonstrated by sealer extrusion as a “puff” on the postoperative radiograph.

Discussion

The lateral canals have a great clinical importance in endodontic therapy, mainly when associated with lateral lesions. The radiographic examination is not accurate in diagnosing accessory and lateral canals, but it can show the presence and the filling, when occur, of these little ramifications.

In 1967, Herbert Schilder described a new technique for filling the endodontic space, the vertical compaction technique of heated gutta-percha, in his article “Filling root canals in three dimensions”, published in the Dental Clinics of North America Journal, a revolutionary article at that time⁽⁴⁾.

Compared to other root canal filling techniques, vertical compaction of heated gutta-percha ensures filling the endodontic system with a dimensionally stable material, biologically tolerated such as gutta-percha. The softened gutta-percha allows for faithful replication of the internal configuration of the endodontic system. Additionally, vertical compaction most commonly seals the lateral and accessory canals as well. A premise for achieving this technique is a progressively uniform tapered preparation of root canal⁽⁶⁾.

Several studies proposed different filling techniques to achieve better obturation of lateral canals: continuous wave of condensation, thermomechanical compaction, or lateral condensation. Although some studies doubt on the idea that the type of root canal filling technique could have a great effect on the number of lateral canals filled⁽⁷⁾, others have demonstrated that warm vertical condensation of gutta-percha increases the capacity of lateral canal filling^(8,9).

Conclusions

The lateral canals can be present as a ramification along the main canal, and they have a great clinical importance in endodontic therapy when the pulp becomes diseased. In this case, the three-dimensional obturation of the root canal system becomes extremely important, preventing reinfection and ensuring the better healing of periapical and periradicular lesions.   n

Acknowledgements. All the authors have equal contributions for this article.

Corresponding author: Irina-Maria Gheorghiu, e-mail: igheorghiu@hotmail.com

CONFLICT OF INTEREST: none declared.

FINANCIAL SUPPORT: none declared.

This work is permanently accessible online free of charge and published under the CC-BY.