INTERNAL ANATOMY OF THE C-SHAPED MANDIBULAR SECOND MOLAR: A LITERATURE REVIEW

Abstract

The internal anatomy of the lower second molar presents remarkable complexity, with the "C"-shaped configuration being one of the most challenging variations for endodontic practice. Therefore, this work consists of a literature review aiming to describe the main morphological characteristics, their prevalence, and the clinical implications of this unusual anatomy. This is an integrative literature review that aimed to map and synthesize evidence on the challenges in the endodontic treatment of lower second molars with a C-shaped configuration. The search encompassed PubMed/MEDLINE, SciELO, and LILACS, with terms combined by AND/OR; the strategy for PubMed used: ("C-shaped canal" OR "c shaped canal" OR "c-shaped root") AND ("mandibular second molar" OR "lower second molar*") AND ("endodontic treatment" OR "root canal therapy" OR "endodontics"). Fourteen full-text articles (2021–2025) were selected, and their data will be organized into a standardized table with author, year, objectives, methodology, results, and conclusions to facilitate synthesis. Results: Prevalence of C-shaped canal varies by ethnicity: up to 47% in Asians, 21-24% in Brazil, 8-14% in Westerners, with bilaterality of 54-92%. CBCT is the diagnostic gold standard. Obturation with thermoplastic techniques and bioceramic cements. The lingual wall of the C2 type is thinner, requiring caution. Conclusion: Endodontic treatment of the second lower molar with C-shaped anatomy is complex and requires preoperative CBCT, adaptive instrumentation, ultrasonic irrigation, and thermoplastic obturation with bioceramic cements. Recognition of anatomical variation and bilaterality is essential for success and prevention of iatrogenic events, although more studies with long-term follow-up are needed.