Objective The present study aimed to analyze the influence of odontogenic factors on maxillary sinus mucosal thickening using cone beam computed tomography (CBCT). Simultaneously, this study evaluated the effect of dental treatment on maxillary sinus mucosal thickening through the follow-up. Methods This study retrospectively reviewed patients with mucosal thickness thickened more than 2 mm in the maxillary sinus selected by CBCT in West China Hospital of Stomatology, Sichuan University from August 2017 to December 2017. Herein, the relationship between the floor of the maxillary sinus and the affected teeth was evaluated while the affected teeth and relevant dental treatment were recorded, and the changes in maxillary sinus mucosal thickening were observed. Results A very weak negative correlation was found between the mucosal thickness and the distance from the inflammation to the sinus floor (P<0.05, r=-0.154), whereas the distance from the root apex to the sinus floor had no direct correlation with the mucosal thickness (P>0.05). In the treatment group, the change of mucosal thickness in the sinus floor destruction group was larger than that in the continuous sinus floor group. In addition, the change in mucosal thickness was weakly negatively correlated with the distance from the root apex to the sinus floor (P<0.01, r=-0.382), meanwhile the change in mucosal thickness was moderately negatively correlated with the distance from inflammation to sinus floor (P<0.001, r=-0.524). Conclusion The severity of maxillary sinusitis may be more dependent on the distance of the periapical inflammatory margin from the sinus floor rather than the simple apical position. On the contrary, the closer the inflammation is to the maxillary sinus, the larger destruction of the maxillary sinus floor. Furthermore, the greater the influence of odontogenic factors on maxillary sinusitis, the better the effect of the oral treatment.