This study aimed to evaluate the association between periodontitis and chronic rhinosinusitis (CRS) via cone-beam-computed tomography (CBCT) using the Lund–Mackay staging system. CBCT images from different departments of the school of dentistry, at Prince Sattam University were evaluated for the presence of rhinosinusitis. All the CBCT scans were exposed for multiple indications, and no patients had a scan exposed solely for this study. The Lund–Mackay staging system was used to measure the CRS in the CBCT. Descriptive statistics for the frequencies and percentages were used to summarize the data. Logistic regression was used to examine the associations between periodontitis and CRS. Each variable was assessed individually by using multivariable analysis. Collinearity issues among the variables were solved to select a limited set of factors using a stepwise variable selection procedure. A total of 399 CBCT images were included in the current research. Logistic regression showed that only gender was significantly associated (p = 0.0001) with the presence of CRS. However, a stepwise variable selection procedure included gender and bone loss as significantly associated with CRS. No significant difference was observed between unilateral vs. bilateral CRS in gender, bone loss, medical status, and periodontitis. However, only gender showed a significant difference in both bilateral vs. no CRS and unilateral vs. no CRS. Periodontitis is not associated with CRS. However, gender has a significant influence on CRS.