This study aimed to figure out both dental and sinus-related variations according to maxillary ostia in 385 patients and 770 maxillary sinuses. It also assessed the importance of PMO and AMO in oral surgeries, especially sinus lift operations.
A study by Hwang et al. found that the PMO was localized 29.9 mm ± 5.1 mm above the palatal bone in the South Korean population, regardless of sex differentiation [7]. The difference between the outcomes might result from the difference in anatomical formations. The standardization of the area was difficult because of the complexity of the region. In the present study, the medial sinus wall was examined by dividing it into three parts to make more standard and comparable measurements.
Hwang et al. reported that the PMO moved inferiorly and laterally as age increased [7]. The reason for the displacement of PMO was that the mid-face moved clockwise with respect to the cranial base as the age increased. However, the number of participants in different age groups should be increased to better interpret the relationship between age and PMO height. The sinus lift should be carefully evaluated, especially in elderly individuals.
The results of this study showed a statistically meaningful relationship between age and PMO diameter. However, Yeung et al. did not find any involvement between PMO diameter and age [8]. The difference between both studies might be due to the age distribution of the patient population included in the study.
A statistically meaningful relationship was detected between PMO diameter and CB. The PMO diameter was found to be 1.95 mm in the presence of CB. One of the significant findings of this study was that the increased PMO diameter in the presence of CB might negatively affect the airflow in the sinus.
Yeung et al. reported that an obstructive PMO was more common in the case of a pathological increase in the thickness of the SM [8]. Guo et al. reported that the PMO was narrowed immediately after sinus floor augmentation surgery but returned to its baseline after 6 months [9]. Shanbag et al. stated that narrowing in the PMO was frequently found on the SM with thickness more than 10 mm [10]. A comparison of the findings with those of other studies confirmed that sinus drainage was impaired in the absence of PMO, and therefore SM thickening occurred.
In the present case, the PMO reached its maximum diameter in the presence of an SM with a thickness of more than 20 mm. The narrowing or widening of the PMO diameter, unlike its physiological width, caused similar effects on SM. Kirhene et al. stated that a widening of the maxillary ostium had negative effects because of the decrease in the nitric oxide (NO) level[11]. The decrease in the NO level caused reinfection of the sinus, and hence the SM thickness increased. One of the most important outcomes of the study was that the presence of PMO decreased and the presence of AMO increased when the thickness of the SM increased. A possible explanation for this might be that sinus drainage disorder occurred with SM thickening.
Another important result to mention was the relationship between PMO height and SM thickness. No studies that established a relationship between these two factors were encountered in literature reviews conducted so far. It is predicted that air circulation in the maxillary sinus is impaired with increasing the PMO height, and thus SM thickening occurs.
The presence of AMO has gained importance due to the increase in surgical procedures involving the sinus area [8]. However, the findings revealed that the SM was thicker in the presence of AMO. This situation supported the assumption that the AMO was a pathological variation rather than a physiological one.
A statistically significant relationship was detected between SD and the presence of AMO. The study by Ozel et al. found the AMO more frequently on the side with SD [12]. The reason for this was shown as SD disrupting the airflow of the maxillary sinus and the pathological presence of AMO.
PMO diameter, height, and presence of AMO should be included besides the factors to be considered before sinus lift, which Tavelli et al. listed in their systematic review in 2017. Considering the outcome observed in the present study, it was presumed that the patency and location of the PMO should be carefully evaluated before the surgical operation to prevent the obstruction of the ostium, especially when a significant amount of grafting was needed. Therefore, in the consensus decision published by the European Osseointegration Association in 2011, it was emphasized that expanding the FOV of the CBCT to include the osteomeatal complex is important to avoid postoperative complications [13]. Consequently, it was anticipated that a detailed and conscious examination of the surgical area with CBCT might contribute to predicting possible complications and factors to be evaluated before surgery. Considering these factors during the treatment planning phase may ensure the avoidance of complications and long-term success.