Introductionįunctional endoscopic sinus surgery (FESS) is highly performed as the current treatment for diseases of nose and paranasal sinuses (PNS).
CBCT is beneficial in evaluating these variations due to its low radiation dose. Although the prevalence of the dangerous types (Keros type 3, Gera type III, and TMS type 3) was low, preoperative assessment is essential in reducing surgical complications. The most prevalent variations of the ethmoid roof were Keros type II, Gera type II, and TMS type 1. 95.43%, 4.17%, and 0.40% of patients were of types 1, 2, and 3 of TMS classification, respectively. There was not significant difference in the Gera classification among males and females. 33.9% of the patients had asymmetry in the Gera classification.
29.57% of the cases had type I, 61.42% had type II, and 9.01% had type III of Gera classification. No significant difference was seen in the Keros classification among males and females, and asymmetry in the depth of the cribriform plate was seen in 33.3% of patients.
The distribution of Keros types 1, 2, and 3 was 20.43%, 66.26%, and 13.31%, respectively. The risk of injury to the skull base was assessed by TMS classification. The degree of the angle formed by the LL and the continuation of the horizontal plane passing through the cribriform plate was calculated. The depth of the olfactory fossa (OF) was defined by the height of the lateral lamella (LL). This study is designed to assess the variations of the ethmoid roof through the Keros, Gera, and Thailand-Malaysia-Singapore (TMS) classifications by means of Cone-Beam Computed Tomography (CBCT).