Evaluation of the pterygoid hamulus morphology using cone beam computed tomography Kaan Orhan, DDS, PhD, a,b Bayram U. Sakul, PhD, c Ulas Oz, DDS, PhD, d and Burak Bilecenoglu, DDS, PhD, e Ankara and Mersin, Turkey UNIVERSITY OF ANKARA, NEAR EAST UNIVERSITY, ANKARA UNIVERSITY, AND UFUK UNIVERSITY Objective. This study consists of anatomic research of the pterygoid hamulus (PH) using 3D cone beam computed tomography (CBCT) images reconstructed from a volumetric rendering program. Study design. Three hundred ninety-six sides in the CBCT scans of 198 (115 men and 83 women) patients were retrospectively analyzed. DICOM data of the patients were transferred to a surface-rendering software so as to generate 3D hard tissue surface representations of PHs. The width, length, angle, and the distance between posterior nasal spine and tip of the PH were measured. In addition, the inclinations of PHs were also evaluated in sagittal and coronal planes of the 3D images. Pearson  2 and Student t test were performed for statistical analysis among age, localization, and measurements (P  .05). Results. The mean PH measurements of left and right sides were 1.72 (SD 0.94) and 1.87 (SD 1.17)-mm width, and the lengths were 5.48 (AD 1.94), and 5.40 (SD 2.0) mm, respectively, with no significant difference (P  .05). All PHs were inclined toward the lateral side in the coronal plane, whereas PHs tended to incline toward the posterior rather than anterior in the sagittal plane (78%). The results showed no statistically significant differences among age, localization, and measurements of PHs (P  .05). Conclusions. Knowledge about the morphology of these structures is helpful for the interpretation of imaging and provides valuable information in the differential diagnosis of untraceable pains in the oral cavity and pharynx. Because of potential problems owing to PH morphology and elongation, oral and maxillofacial radiologists should assess the radiographic images thoroughly. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:e48-e55) A broad definition of pterygoid hamulus (PH) is a hooklike projection at the inferior end of each medial plate of the pterygoid process. The medial pterygoid plate of the sphenoid bone curves laterally at its lower extremity into a hooklike process, the PH, around which the tendon of the tensor veli palatini (TVP) muscle glides. Although the PH is, because of its bi- zarre shape, a striking feature of the skull base, it is still an unexplored region on the anatomical map. 1,2 Only a few studies have been conducted on the morphology of PH 1-4 ; however, because of its close relationship to the maxilla and oropharynx, it is of interest to all disci- plines that are involved with this region. 1 The position, length, and inclination of PHs are of great importance for the function of several muscles: tensor veli palatini, palatopharyngeus, and upper part of the upper pharyngeal constrictor, pars pterygopharyn- gea. These muscles contribute to the separation of the oral from the nasal cavity during sucking and swallow- ing during growth and development and into adult- hood. 2,3 Elongation of PH was also associated with a rare syndrome of PH that shows various and complex symp- toms in the palatal and pharyngeal regions and also causes pain and discomfort especially during swallow- ing. The term pterygoid hamulus syndrome was first used to describe a pain in the palatal and pharyngeal regions caused by an abnormally shaped PH by Hjørt- ing-Hansen et al. 5,6 in 1987 with about 40 cases re- ported in the literature. 4-15 Several studies were conducted on the position and morphology of PH in different populations. According to those studies, the length of the PH was found to be within the range of 4.9 to 7.2 mm. 1-4,10 Putz and Kroyer 1 also reported the sagittal and transverse diam- eter of PH as 1.4 mm and 2.3 mm, respectively, whereas Sasaki et al. 10 also reported an elongated PH of a Associate Professor, Department of Oral, Tooth and Jaw Radiology, University of Ankara, Faculty of Dentistry, Ankara, Turkey. b Associate Professor, Department of Oral, Tooth and Jaw Radiology, Near East University, Faculty of Dentistry, Mersin, Turkey. c Professor, Department of Anatomy, Ankara University, Faculty of Dentistry, Ankara, Turkey. d Assistant Professor, Department of Orthodontics, Near East Univer- sity, Faculty of Dentistry, Mersin, Turkey. e Assistant Professor, Department of Anatomy, Ufuk University, Fac- ulty of Medicine, Ankara, Turkey. Received for publication Oct 16, 2010; returned for revision Feb 17, 2011; accepted for publication Feb 22, 2011. 1079-2104/$ - see front matter © 2011 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2011.02.038 e48