The bones of the skull contain many air-filled cavities, which are referred to as pneumatization. Ten sites of air cells can be found within the temporal bone, including the zygomatic process of the temporal bone which is termed the pneumatized articular eminence (PAT) and the roof of the glenoid fossa. The term PAT was used for the first time by Tyndall and Matteson to describe air cells that occur in the root of the zygomatic arch and in the articular eminence of the temporal bone, that is, similar to air cells in the mastoid process and ethmoid bone. These authors also identified its common characteristics as: an asymptomatic radiolucent defect in the zygomatic process of the temporal bone with an appearance similar to mastoid air cells; extension of the defect anteriorly as far as the articular eminence but not beyond the zygomaticotemporal suture; and no enlargement or cortical destruction of the zygoma. Additionally, they classified the PAT as unilocular or multilocular.

Knowledge of these pneumatizations adjacent to the temporomandibular joint (TMJ) is important as they represent sites of minimal resistance and facilitate the spread of various pathologies into the joint as inflammation, tumour or fractures. Tumours of the mastoid process and ear may extend into the TMJ, while otitis or mastoiditis may involve the TMJ and can result in ankylosis. They are possible complicating factors in TMJ surgery so several authors have recommended that imaging studies should be performed prior to any surgical procedure.

Panoramic radiography is considered useful to display the PAT, for that reason many case reports and prevalence studies on PAT are based on the use of this radiography ; other conventional projections of the skull do not provide adequate visualization of the posterior aspect of the zygomatic arch. Panoramic radiographs are considered the initial method to evaluate these defects because they are obtained during routine examination of many patients; in comparison to computed tomography (CT) they are cheaper and incur a lower radiation dose. These disadvantages have been overcome now cone beam CT (CBCT) is increasingly replacing CT because it provides an adequate image quality associated with lower radiation exposure, fast scanning time, lower number of image artefacts and real time image analysis. Since CBCT does not present superimposition of images, it surpasses the diagnostic accuracy of panoramic radiographs in the evaluation of temporal air spaces.

To the authors’ knowledge, only one study of the prevalence of PAT using CBCT has been performed. The authors evaluated the prevalence in the Turkish population; they concluded it could be possible that PAT is more frequent than is perceived and suggest more prevalence studies, particularly from developing countries. The authors did not evaluate the pneumatization of the glenoid fossa (PGF), which has the same clinical importance in the spread of pathologies into the joint and as a possible complicating factor in TMJ surgery. The aim of this study was to determine the prevalence and characteristics of pneumatization of the glenoid fossa and articular eminence regarding the age, gender, laterality and type by means of CBCT images in a population in a developing country.