Anatomical relationship between the maxillary posterior teeth and the sinus floor according to an anterior overbite.

Objective To evaluate the vertical relationship between the maxillary sinus floor (MSF) and the maxillary posterior teeth (MPT) according to an anterior overbite. Settings and Sample Population The patients were divided into three groups according to an anterior overbite. The open bite group (OBG) included patients with an anterior overbite of <= 0 mm, the normal overbite group (NBG) included patients with an overbite of 0-3 mm, and the deep bite group (DBG) included patients with an overbite >= 3 mm. Thirty patients were randomly matched into each group based on age and sex. Materials and Methods The distances and vertical relationship between the MSF and the MPT was analysed using cone-beam computer tomography. The vertical relationship between the two was classified as either favourable or unfavourable for the intrusion of the posterior teeth. Results A higher ratio of patients in the OBG had MPT positioned close to the MSF than the DBG. Intrusion of the posterior teeth was unfavourable for an average of 87.2%, 77.2% and 70.2% molars in the OBG, NBG and DBG, respectively. Conclusions The vertical distance between the MSF and the MPT is associated with an anterior overbite. The posterior teeth were in an unfavourable position for the orthodontic intrusion in the OBG as compared to the other groups. Additional caution is needed when planning orthodontic intrusion treatment for patients with an anterior open bite. But, there were some individual variations within each group.