Study design: The study design consisted of a retrospective clinical chart review.
Methods: In total, 217 patients (110 females and 107 males; average age, 33.14 ± 12.88 years; age range: 18–65 years) were included in the study. The patients were divided into 3 groups in terms of the degree of the mastoid pneumatization. The mastoid pneumatization was measured between 0 and 5 cm3 for group A, between 5 and 10 cm3 for group B, and ≥10 cm3 for group C. The ETa and ETl of each group were compared.
Results: The mean mastoid pneumatization of groups A, B, and C was 4.32 ± 1.96, 8.26 ± 2.68, and 11.94 ± 1.28 cm3, respectively. The ETl of group A was lower than that of other groups statistically (P = 0.006 and 0.018, respectively). The mean ETl did not differ between the groups B and C (P = 0.698, >0.05, respectively). The ETa of each group did not differ (all P > 0.05). The mastoid pneumatization and the ETl were higher in males than in females (P = 0.004 and 0.001, respectively). The ETa did not differ between males and females (P = 0.0158). There was a positive correlation between the degree of the mastoid pneumatization and the ETl (r = 0.159/P = 0.002,