Statistical analysis
Data were expressed as the mean and standard deviation for comparison between the presence and absence of accessory maxillary sinus ostia in superior meatus in both left and right sides of the maxillary sinus. Statistical analysis was performed using one-way analysis of variance and Tukey test (SigmaPlot 12.5), with a P value of <0.05 considered statistically significant. Sample size calculations were based on an alpha of 0.05 and a power value of 0.99.