Inferior Alveolar Nerve Damage Because of Overextended Endodontic Material: A Problem of Sealer Cement Biocompatibility? Jaume Escoda-Francoli, DDS,* Carles Canalda-Sahli, MD, DD, PhD, † Albert Soler, PhD, ‡ Rui Figueiredo, DDS,* and Cosme Gay-Escoda, MD, DDS, PhD §, Abstract Damage to the inferior alveolar nerve is a relatively infrequent complication in dental practice. When root canal treatment of a lower molar or premolar surpasses and/or overextends beyond the apical foramen and invades the periapical zone, the foreign material intro- duced within such a sensitive anatomical space may mechanically or even chemically affect the inferior al- veolar nerve. We describe a case of endodontic treat- ment of a permanent right lower first molar in which the sealer cement overextended in large amounts and damaged the right inferior alveolar nerve. The condition reverted a few months after the surgical removal of the material. Evaluation of the removed material, using powder x-ray diffraction and scanning electron micros- copy with coupled dispersive energy spectroscopy, showed it to consist of calcium tungstate (scheelite [CaWO 4 ]) and zirconium oxide (baddeleyite [ZrO 2 ]), which were chemical components of the sealer cement. (J Endod 2007;33:1484 –1489) Key Words Biocompatibility, endodontic treatment, inferior alveo- lar nerve damage S ensory loss or alteration in the territory of the inferior alveolar nerve (IAN), the chin region, and lower homolateral half of the lip is a relatively infrequent complication in daily dental practice and is normally the result of an inadequate dental treatment (1). One of the potential iatrogenic causes of this problem is the incorrect treatment of the root canals of a lower molar or premolar (overextension and/or overfilling). The mechanism by which such treatment can damage the IAN may be mechanical, thermal, or chemical (2). The trajectory of the IAN with respect to the apexes of the teeth in the posterior mandibular sector determines the greater or lesser likeliness of this type of complication (3). There have been reports of IAN damage in up to 1% of cases when performing defective root canal treatment (overextended or overfilled) of a lower premolar (4). The different filling systems used in endodontics as well as the type of sealer cement used can also influence the incidence of this complication to one degree or another (5). Such problems must be resolved as quickly as possible to avoid irreversible se- quelae caused by certain scantly biocompatible materials that form part of endodontic sealants (6). Surgery is usually the most reliable option for recovering damaged nerve function. The most commonly used technique to remove the overextended or overfilled material endodontic is apical curettage with or without periapical surgery, depending on whether the affected tooth is to be preserved or not. Nevertheless, in exceptional cases, it may be advisable to perform a mandibular sagittal split procedure (3, 7). Adequate planning of the surgical procedure to ensure minimum trauma requires a complete preoperative radiologic study. The present article describes a case of IAN damage after endodontic treatment of a right lower first molar, with structural and chemical characterization of the inorganic components of the sealer cement in order to identify possible biocompatibility prob- lems. A review of the literature on the subject is also provided. Clinical Report A 41-year-old white woman without systemic pathology reported to the Oral Sur- gery Unit (Dental Clinic, Barcelona University Dental School, Barcelona, Spain) with an infectious condition (with light pain and purulent drainage) in the right mandibular zone (area of missing molar) and paresthesia of the lower right half of the lip and chin region. After complete anamnesis and clinical and radiologic studies (Figs. 1 and 2), the edentulous zone of the right lower first molar was seen to contain several foreign bodies within the socket and in the vicinity of the inferior dental canal, resulting from root canal treatment performed 4 months earlier. After the mentioned treatment, the patient re- ported an important decrease in sensitivity of the lower right-side chin and lip zones. The dentist removed the previously mentioned molar to resolve the symptoms, although to no avail. Before being submitted to surgery, the patient was initially treated with an antibiotic (amoxicillin 875 mg, and potassium clavulanate 125 mg) and a nonsteroidal anti-inflammatory drug (ibuprofen 600 mg) for 7 days. This medication had no effect on the paresthesia. Two months after the first appointment at our center, a surgical procedure was performed under local anesthesia (4% articaine plus adrenalin 1:100,000) and intravenous sedation (remifentanil, propofol, and midazolam). The surgeon raised a triangular full-thickness flap, which was protected by a Minnesota retractor. After the mental nerve was identified, a vestibular bone removal was per- From the Departments of *Oral Surgery and Implantology, † Endodontics, and § Oral and Maxillofacial Surgery, Barcelona University Dental School, Barcelona, Spain; ‡ Department of Crystallography, Mineralogy and Mineral Deposits, Barcelona University, Barcelona, Spain; and  Department of Oral and Maxillofacial Surgery, Teknon Medical Center, Barcelona, Spain. Address requests for reprints to Dr Cosme Gay-Escoda, Centro Medico Teknon, C/Vilana 12, 08022 Barcelona, Spain. E-mail address: cgay@ub.edu. 0099-2399/$0 - see front matter Copyright © 2007 by the American Association of Endodontists. doi:10.1016/j.joen.2007.09.003 Case Report/Clinical Techniques 1484 Escoda-Francoli et al. JOE — Volume 33, Number 12, December 2007