Maxillary Sinus and Posterior Teeth: Accessing Close Relationship by Cone-beam Computed Tomographic Scanning in a Brazilian Population Ot  avio Pagin, DDS, MS, Bruna Stuchi Centurion, DDS, MS, Izabel Regina Fischer Rubira-Bullen, DDS, MS, PhD, and Ana L  ucia Alvares Capelozza, DDS, MS, PhD Abstract Introduction: This study aimed to evaluate the close proximity established between the maxillary sinus floor and posterior teeth roots apices by using cone-beam computed tomographic scanning. Methods: The rela- tionship of maxillary sinuses and posterior teeth roots, which were divided into 2 groups, was analyzed using i-CAT Vision software (Imaging Sciences, Hatfield, PA). Group 1 included all root apices found in close contact with the maxillary sinus floor without sinus floor eleva- tion, whereas group 2 included all root apices that were protruded within the sinus producing an elevation of the bony cortical. Results: A total of 100 maxillary sinuses and 601 roots apices were evaluated. Group 1 presented 130 of 601 (21.6%) roots and group 2 presented 86 of 601 (14.3%) roots. Conclusions: The second molar me- siobuccal root apex is frequently found in close prox- imity with the sinus floor, and the relation between these anatomic structures should be considered in order to prevent an iatrogenic procedure and minimize the risks from an infectious disease within the sinus. (J En- dod 2013;39:748–751) Key Words Bicuspid, cone-beam computed tomography, endodon- tics, maxillary sinus, molar, tooth apex T he maxillary sinus floor (MSF) may extend beneath the posterior teeth roots or between adjacent teeth, creating recesses that require attentive observation before an endodontic procedure (1). Close proximity between the MSF and root apex may facilitate bacterial infection from a periapical disease spreading within the maxillary sinus (2, 3) and may lead to mucositis, sinusitis (3, 4), or endoantral syndrome (5). The introduction of endodontic instruments, intracanal medicaments, or root filling material into the maxillary sinus produces an inflammatory response in the sinus mucosa (1). This close relationship is also relevant during periapical surgery because it can result in sinusitis and sinus membrane thickening caused by mucosal perforation (6). Cone-beam computed tomographic (CBCT) scanning provides an accurate 3- dimensional evaluation of maxillary bone around posterior root apices without the distortion and superimposition caused by teeth and the surrounding structures, as in periapical radiography (7, 8). It is traditionally believed that the contact between posterior teeth root apices and the MSF gets closer as one moves from the anterior region toward the posterior one (9, 10). The aim of this study was to verify the close proximity between the MSF and the maxillary posterior root apices in CBCT images in a Brazilian population. Materials and Methods A total of 100 maxillary sinuses in 50 CBCT examinations obtained with a 0.3-mm voxel size were randomly selected, and i-CAT Vision software (Imaging Sciences, Hat- field, PA) was used to evaluate all images on a 20-inch Eizo FlexScan S2000 monitor (Eizo Nanao Corporation, Hakusan, Ishikawa, Japan). The exclusion criteria used were the presence of unerupted maxillary teeth and cystic, tumorous, or traumatic lesions on the upper jaw. The inclusion criterion was that the patient needed to be at least 21 years old. This study was approved by the Bauru School of Dentistry Ethics in Research Committee, University of S ~ ao Paulo (process 048/2009). Image Interpretation A standard sequence for the evaluation of the MSF and posterior maxillary teeth was established, starting with the parasagittal reconstructions from the posterior area and moving toward the anterior area (the right and left sides, respec- tively). Then, the axial, coronal, and sagittal reconstructions were used sequentially to confirm the parasagittal screen findings. The close proximity between the MSF and maxillary posterior teeth apices visually evidenced no bone separating these anatomic structures. Group 1 included the root apex in close contact with the MSF with no root protrusion within the maxillary sinus and no elevation produced in the sinus floor trajectory (Fig. 1A). In group 2, the root apex was in close contact with the MSF, protruding into the sinus with small elevations produced on the sinus floor trajectory (Fig. 1B). The first and second molar roots were individually analyzed in the following estab- lished sequence: palatine, distobuccal, and mesiobuccal. No root differentiations were made to the third molars and premolars because in most of the cases observed these From the Department of Stomatology, Bauru School of Dentistry, University of S~ ao Paulo, Bauru, S~ ao Paulo, Brazil. Address requests for reprints to Dr Ot avio Pagin, Depart- ment of Stomatology, Bauru School of Dentistry, University of S~ ao Paulo, Al Dr Oct avio P. Brisolla, 9-75, Vila Universit aria, 17012-901 Bauru, SP, Brazil. E-mail address: pagin@usp.br 0099-2399/$ - see front matter Copyright ª 2013 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.01.014 Clinical Research 748 Pagin et al. JOE — Volume 39, Number 6, June 2013