| 16 | Smile Dental Journal | Volume 8, Issue 3 - 2013 ABSTRACT The aim & objective of this study is to investigate the frequency and type of C-shaped root canals in mandibular second molars of the UAE population. The teeth with C-shaped canals were classifed using Melton’s classifcation. Method: Ninety-six mandibular second molars of patients aged between 20-45years old, scheduled for endodontic treatment, were examined over a 2-year period in the Endodontic Department, Tawam Hospital, Dental Center, UAE. C-shaped canals were detected and counted. Two detection procedures, radiography and clinical examination, were used. Results: Thirty three exhibited C-shaped canals (34.37%). Eleven molars presented a continuous C-shaped canal (11.4%), category I. Seven (7.2%) had a semicolon shape with a mesial canal located on the buccal or lingual side depending on where the fusion occurred, category II. In many instances, this canal swung back and merged with the distal canal, thus yielding a single foramen, in the other cases, it remained distinct with its own portal of exit. Fifteen (15.6%) were considered as category III: Three for subdivision I, two for subdivision II, and ten for subdivision III. Conclusion: The frequency of C-shaped root canals in mandibular second molars is high in the UAE patients. KEYWORDS C-shaped canals, Endodontic treatment, Obturation. C Shaped Root Canals in Mandibular Second Molars in UAE Nationals Salma B A Abdo – BDS, MSc, PhD Specialist Endodontist, Head of Endodontic Department, Tawam Hospital | Dental Centre Al Ain, UAE – Sabdo@tawamhospital.ae INTRODUCTION Knowledge of the anatomy of the root-canal system in teeth is essential for its successful debridement and obturation. With information gleaned from preoperative dental radiography, the clinician can assess, to a great extent, the anatomic challenges in each tooth. 1 Of particular interest is the canal confguration of the mandibular second molar, as a great deal of variation can occur. The C-shaped canal system is an anatomic variation occurring mostly in mandibular second molars, especially in Asian populations, although it can also occur in maxillary and other mandibular molars. 2-7 The main anatomic feature of the system is the presence of a fn or web connecting the individual root canals. The orifce may appear as a single ribbon-shaped opening with a 180º arc in the form of a band or a deep semi lunar groove connecting the distal, mesio-buccal and mesio-lingual canals 8 (Figs 1, 2). The concavity of the C may be oriented buccally or lingually. In other cases, the orifce may take the form of an incomplete C, with union of the distal and mesio-buccal canals and the presence of an isolated mesio-lingual canal, giving the canals the appearance of a semicolon. 9,10 It may also present as a C-shaped canal with union of the distal and mesio- lingual canals with a separate mesio-buccal canal. It is important to emphasize that this C-shaped variation of the anatomy can occur throughout the length of the root canal, which complicates the stages of biomechanical preparation and obturation. Once recognized the C-shaped canal presents a challenge with respect to diagnosis, debridement, obturation and prosthodontic restoration 8,11-16 because it is unclear whether the C-shaped orifce found on the foor of the pulp chamber actually continues to the apical third of the root. 8 Amera Alkaisi – BDS, MSc, PhD Lecturer in College of Dentistry, Oral & Maxillofacial Surgery | University of Anbar, Iraq ameraalkaisi@gmail.com (Fig. 1) C-shaped chamber foor showing a complete C-shaped root-canal orifce in the form of a deep trough connecting the distal, mesio-buccal and mesio- lingual canal orifces (Fig. 2) C-shaped chamber foor of mandibular second molar with mesial, distal and mid-buccal canal orifces after Obturation