Knowledge of the anatomical course of the anterior maxillary wall and alveolar process arteries is essential for sinus lift procedures. The aim of this study was to analyse the localization of anastomoses between the infraorbital and posterior superior alveolar artery on 101 computed tomography (CT) scans of maxillary sinuses (patients aged 18–70 years). The distance from the anastomosis to the bone point was measured on CT scans for each tooth location; for edentulous patients measurements were made to the lower edge of the alveolar process, and for dentate patients to the neck of the tooth. Measurements were done independently by two observers. The anastomosis analysed was identified on 50% of CT scans. The distance to the anastomosis was longest above the premolar (20.4 mm from tooth cervical line) and shortest above the first molar (15.9 mm to the edge of the alveolar process). The anastomosis can be localized on a CT scan for exact positioning of the antrotomy in 50% of patients. For the remaining patients, the anatomical information provided in this study can be used to reduce the risk of damage to the anastomosis. This study provides information on the distance from the anastomosis to the neck of preserved teeth in partially edentulous patients, which can be used as a reference point during sinus lift procedures.
Alveolar process resorption after tooth loss in the maxilla causes thinning of the bone. There are various methods for bone augmentation before implantology treatment in this region. The most common are the sinus lift described by Boyne and James, onlay bone grafts, the ‘minimal invasive sinus lift’ performed with an endoscope, and the local sinus lift for single tooth implantation.
The location of the arteries of the anterior maxilla body wall limits the size of the bone window that can be created during sinus lift surgery. The most important vessels in this region are the posterior superior alveolar artery (PSAA) and the infraorbital artery (IOA) connected by an anastomosis. Studies of the anatomy of these arteries have been done on adult specimens, fetuses, and on computed tomography (CT) scans.
The arteries of the anterior maxillary walls are important because they provide vascularization to the alveolar process, which is necessary for good healing and the integration of grafted bone. The upper part of the bone incision can damage the anastomosis, as shown in Fig. 1 . A method of precise localization of the arteries in relation to easily identifiable anatomical structures could reduce the risk of such damage. The aim of this study was to identify the anastomosis on CT scans and to measure the distance of the anastomosis from the alveolar process or teeth.
Materials and methods
We reviewed 156 consecutive CT scans of the maxillary sinus performed for a suspected sinus pathology. The scans were obtained using a GE LightSpeed 16 CT instrument (GE Healthcare) with a slice thickness of 3.75 mm, using the sinus examination protocol. Studies that revealed a pathology of the maxillary sinus cavity or its walls were excluded. One hundred and one studies in patients aged 17–80 years (mean age 43 years), with an equal distribution of the sexes, were selected. All scans were analysed independently by two investigators using the Centricity DICOM Viewer (GE Healthcare). The first step in the evaluation of CT scans was the identification of the arteries in the anterior wall of the maxillary sinus (artery canal or sulcus). Any differences between the investigators regarding the visibility of the artery were resolved by joint review of the CT scans until consensus was reached.
When the position of the artery was identified, measurements were made of the distance from the artery canal to either the lower edge of the alveolar process (when the teeth were absent) or to the cervical line of the tooth on the coronal scans taken at the level of the tooth or at the level where the missing tooth had been located ( Figs. 2 and 3 ). These distances were measured at the level of each molar and premolar tooth ( Fig. 1 ).