Background: The maxillary artery (MA) and its terminal branches are commonly damaged in the maxillary
osteotomy, especially during separation of the pterygomaxillary junction (PMJ).
Objective: To evaluate the positional relationship between the MA at the pterygomaxillary fissure (PMF) and the PMJ in Thais, as well as to measure the diameter of the MA as it enters the pterygopalatine fossa (PPF) and the heights of PMJ, maxillary tuberosity and posterior maxilla.
Subjects and Method: Both sides of 100 Thai adult cadavers (50 males and 50 females) were examined. The
mean age of the subjects was 64.5 + 12.8 years. With the lateral infratemporal approach, the branches from the third part of the MA, PMJ and posterolateral maxilla were dissected. Measurements taken included the following: First, the distance from the most inferior point of the PMJ to the most inferior position of the MA as it entered the PPF; second, the external diameter of the MA as it entered the PPF; third, vertical heights of the PMJ, maxillary tuberosity and posterior maxilla. Means, standard deviations and ranges were determined and statistical differences were calculated between sides and genders at p < 0.05.
Results: The MA entered the PPF at a mean distance of 23.5 + 2.5 mm above the most inferior point of the PMJ. The mean external diameter of the MA as it entered the PPF was 2.8+ 0.6 mm. The mean heights of the PMJ, maxillary tuberosity and posterior maxilla were 19.5 + 2.3 mm, 6.1 + 2.7 mm, and 25.6 + 3.3 mm, respectively. There were no differences with respect to side and gender, except that the distance from the most inferior point of the PMJ to the most inferior position of the MA as it entered the PPF was longer in males than in females (p < 0.05).
Conclusion: The mean location of the MA was 23.5 mm apart from the most inferior point of the PMJ, therefore, dysjunction of the PMJ using an osteotome with a 15-mm cutting edge may be conducted without damaging to the MA. When properly placed, the margin of safety from the superior cutting edge of the osteotome to the MA is approximately 8 mm in adults.

Keywords: Maxillary artery, Maxillary osteotomy, Pterygomaxillary fissure, Pterygomaxillary junction,
Pterygopalatine fossa