Use of a Single-File Reciprocating R20 in a Complex Retreatment

This case illustrates the value of contemporary reciprocating systems in addressing anatomical variations that can compromise primary endodontic success. A 62-year-old female patient was referred to the author’s practice due to persistent discomfort during mastication localized to the maxillary left first molar. Clinical examination revealed mild percussion sensitivity. A CBCT scan confirmed a previously untreated second mesiobuccal (MB2) canal and a periapical lesion associated with the mesiobuccal root. Thus, nonsurgical orthograde retreatment was chosen. Because the intricate morphology of MB2 canals can prove challenging for traditional rotary NiTi systems, the author has adopted the use of reciprocating single-file techniques, which offer enhanced safety. In this case, the author used the EdgeOne R Utopia™ R20 (EdgeEndo, edgeendo.com), a single-file reciprocating instrument designed for tight, calcified, and/or highly curved canals. Its S-shaped cross-section ensures cutting efficacy and fatigue resistance, while a proprietary heat treatment enhances both torsional strength and flexibility. The case was completed using standard irrigation protocols, followed by single-cone obturation with EdgeOne R Utopia™ gutta-percha points (EdgeEndo) and EdgeBioceramic™ Sealer (EdgeEndo) for a biocompatible and hermetic seal. Postoperative radiographs confirmed a well-centered fill and adequate canal debridement. The patient reported no significant postoperative discomfort and was asymptomatic within days.

KEY TAKEAWAYS

EdgeOne R Utopia R20 successfully negotiated a narrow, double-curved MB2 canal without the need for glide path preparation or multi-instrument techniques. The reciprocating motion reduces continuous torsional stress, improves resistance to cyclic fatigue, and preserves canal anatomy.

R20’s proprietary heat treatment improves torsional resistance and flexibility, enabling safer navigation in highly curved or calcified canals. The R20 maintained working length and canal integrity, minimizing risk of ledging, transportation, or instrument separation.

The case was completed using a true single-file technique, reducing chairtime and preserving conservative canal shaping.

Gianluca Gambarini, DDS

Professor and Head of Endodontics and Restorative Dentistry, La Sapienza University of Rome; Private Practice limited to Endodontics, Rome, Italy

Figures and Images

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Figure 1

Fig 1. The referring clinician had provided a periapical radiograph that showed prior endodontic therapy in the maxillary left first molar involving three canals. The 2-dimensional imaging, however, did not clarify the etiology of the patient’s persistent symptoms.

Figure 2

Fig 2. Because of the diagnostic limitations of the conventional radiography, a CBCT scan was obtained, which confirmed a previously untreated MB2 canal and a periapical lesion associated with the mesiobuccal root. Based on these findings, the clinician opted for nonsurgical orthograde retreatment.

Figure 3

Fig 3. In an MB2 canal, the canal’s double curvature and severely narrowed lumen may impede progress. These challenges often arise when the initial file tip size and taper are too large, limiting file penetration in severely constricted spaces. Rather than abandon the single-file approach in favor of glide path enlargement, in this case the author utilized the EdgeOne R Utopia R20 to negotiate the working length in the MB2 canal. The instrument’s reduced tip size and overall dimensions allowed smoother apical progression, and its pilot tip facilitated safe negotiation without canal transportation or iatrogenic errors. The R20 instrument easily reached working length, maintained canal integrity, and exhibited no signs of deformation postoperatively.

Figure 4

Fig 4. EdgeOne R guttapercha points were used to achieve single-cone obturation. These guttapercha points feature a proprietary stiffening process for improved handling, less tip crumbling, and improved displacement of sealer.

Figure 5

Fig 5. The use of EdgeBioceramic Sealer helps facilitate a biocompatible and hermetic seal. With a resin-free formula, the sealer is hydrophilic, and unlike conventional sealers, it does not shrink, which means the gutta-percha does not need to be compacted. The clinician simply coats the canal walls with the biocompatible sealer and places the gutta-percha point to length.

Figure 6

Fig 6. Postoperative radiographs demonstrated a well-centered fill and adequate canal debridement. The red lines in the image on the right indicate the trajectory of the final step.