Frequency of existence, numbers, and location of the accessory infraorbital foramen

The aim of this study is to analyze the frequency of existence, numbers, and location of the accessory infraorbital foramen (AIOF).In a PubMed search, 166 articles resulted using the term infraorbital foramen (IOF). The abstracts were read, and 15 full-text articles were reviewed. Among them, 13 articles were analyzed.The frequency of the skull containing the AIOF varied (0.8%-27.3%). The overall frequency of the skull having AIOF was 16.9% ± 8.6% (17.0% ± 9.4% in dry skulls and 15.8% ± 3.6% in cadavers). Most (92.2%) of the AIOF were located on the superomedial side of the IOF, whereas 5 (7.8%) were located inferomedially. The AIOFs were found in similar frequency according to the laterality (right, 42.7%; left, 45%; bilateral, 12%; P = 0.794 [binominal test]). The frequency of the AIOF varied according to latitude. Skulls collected greater than 60 degrees had a higher frequency of an AIOF (28.7%) than between 30 and 60 degrees (19.0%) or less than 30 degrees (18.2%) (P = 0.000 [Pearson Chi-squared test], P = 0.000 [trend test]). There was a positive correlation between latitude and frequency of AIOF (y = 0.062x + 18.02, Pearson correlation coefficient = 0.140, P = 0.000).During anesthetization of the infraorbital area or in surgical maneuvering in the maxillofacial region, surgeons should remember the frequency of the AIOF (16.9% ± 8.6%) and its location (92.2% at the superomedial side of the IOF).