OAC associated with maxillary tooth extractions is a relatively common complication Both the planning and timely intervention in the treatment of OAC can pose challenges for clinicians. Panoramic radiographs are commonly used for the prediction of inferior alveolar nerve exposure during wisdom tooth surgeries [25–27], failure of condylar neck osteosynthesis[28], impaction of maxillary canines [29], growth changes associated with orthodontic therapy [30] nd the diagnosis of atheromatous plaque formation in the carotid artery [31]. Panoramic radiographs are generally accepted as diagnostic tools and, in many cases, provide sufficiently reliable measurements [23]. The relationship between the roots of maxillary teeth and the sinus has been evaluated using both panoramic radiographs and CBCT scans [6–9, 11–13, 15, 16, 18]. Although most studies emphasize the superiority of CBCT over panoramic radiographs in assessing the real correlation between the roots and the sinus floor, they do not provide a prediction of the occurrence of post-extraction OAC. Regnstrand et al. reported that approximately 70% of upper first molar roots are in contact with the sinus, with up to a fifth of the root surface (for the palatal root) being involved [7]. However, Punwutikorn et al. found that the incidence of OAC related to upper first molar extractions was only 0.61% [1] suggesting that anatomical observations do not directly translate to clinical findings. According to Sharan & Madjar, the projection of maxillary teeth roots into the sinus is overestimated on panoramic radiographs in both occurrence and length [11]. Jung & Cho reported that, contrary to the appearance of wisdom tooth roots projecting into the sinus on panoramic radiographs, CBCT scans showed that the sinus floor is often located buccally to the roots, mimicking root projection on panoramic images [16]. he risk of OAC during upper wisdom tooth removal has been examined in detail by several studies [17, 19–22], both panoramic radiographs and CBCTs were evaluated, along with clinical parameters. Iwata et al. concluded that the usefulness of CT evaluation as an adjunct to panoramic radiographs in predicting OAC following upper wisdom tooth removal is limited [19]. In addition to root projection into the sinus and depth of impaction, other factors such as a single-rooted tooth, pericoronitis, and "remarkable hemorrhage" were associated with an increased risk of OAC. Hasegawa et al. [20] reported similar outcomes related to the depth of impaction and the root projection, additionally mesioangular position and incision were raised as risk factors. reported similar outcomes related to the depth of impaction and root projection, adding mesioangular position and incision as risk factors. Further risk factors, such as older age and intraoperative root fracture, were reported by Rothamel et al.[22]. A systemic review by Lewusz-Butkiewicz et al.[5] concluded that the relationship between the root of the wisdom tooth and the maxillary sinus can be an important predictive factor, along with older age, mesioangular position, and performed osteotomy during tooth removal. Our study was not conducted focusing solely on wisdom teeth, as the occurrence of OAC is more common and may be a more troublesome consequence when extracting other teeth. Similarly to these articles, "depth," represented in our study by the distance between the cementoenamel junction and the marginal bone, was an important predicting factor for OAC. In cases of impaction and severely destructed teeth with remaining roots below the marginal bone level, negative values of this parameter indicated a higher chance for the formation of an oroantral communication. Angulation other than vertical and the length of root projection into the sinus (maximal root projection) also proved to be significant. Unfortunately, in our retrospective study, operational parameters such as excessive use of an elevator, osteotomy, and excessive bleeding were difficult to address; however, they could have had a remarkable impact. As we examined OAC related to the extractions of canines, premolars, and molars as well, the number of cases is higher (97 OAC) than in those studies that focus on wisdom tooth surgeries (7–46), except for a prospective multicenter study by Rothamel et al.[22].
In a recent study by Vollmer et al.[32], several deep learning models were employed to determine if OAC could be predicted based on preoperative panoramic radiographs. They assessed both expert performance and artificial intelligence (AI) performance in predicting OAC without a preset criteria system. From the 100 OAC cases and 200 controls, they concluded that the prediction of OAC by AI is not yet feasible and that expert agreement on the same matter is poor. In contrast, our study demonstrated excellent expert agreement, which may be the result of a defined, preset evaluation criteria system (see Appendix 1).
Our investigation revealed that neither the presence nor the size of periapical inflammation significantly influences the occurrence of oroantral communication (OAC). This finding may be attributable to the preservation of the cortical bone at the sinus base during bone resorption or to local thickening of the Schneiderian membrane induced by inflammation. Both factors potentially diminish the risk of creating a pronounced, direct connection during tooth extraction. Furthermore, disruptions in the basal contour of the maxillary sinus or the presence of root projections in relation to the sinus base did not demonstrate a significant impact.
The results of our study identified several potential indicators on panoramic radiographs predictive of OAC formation. Both decision tree analysis and binary logistic regression revealed significant correlations with two parameters: the distance between the marginal bone and the cementoenamel junction mesially, and the maximal root projection. While the decision tree offers a clinically relevant heuristic for decision-making, it is important to note that the initial braching point (mesial CEJ to marginal bone distance) provides limited interpretive value, as a negative distance may denote either an impacted tooth or a a root remnant. The depth of impaction or, alternatively, the extent of destruction (distance from the marginal bone to the CEJ or the most coronal part of the root) may affect the development of OAC. This relationship is corroborated by our binary logistic regression analysis, which indicated a 0.721-fold decrease in OAC risk for every millimeter increase in the mesial distance from the CEJ to the bone. The significance of this measure may extend beyond the relative depth of the tooth/root, suggesting that the removal of a root remnant or impacted tooth may necessitate osteotomy or intensive use of elevators, both of which are likely contributory to OAC formation. These potential contributing factors were beyond the scope of this study. Another significant determinant of OAC, identified by both analytical approaches, was the maximal root projection. A one-millimeter increase in maximal root projection was associated with a 1.22-fold increase in OAC risk, with the decision tree threshold set at 3.3 mm. This finding is consistent with prior research by Madjar et al.[11], who demonstrated that root projection into the sinus is overestimated on panoramic radiographs compared to cone-beam computed tomography (CBCT), emphasizing the significance of the extent, rather than the mere presence, of root projection.
Sinus recess and mesial or distal angulation of the tooth were also identified as significant factors by the decision tree. The relevance of sinus recess is underscored by Regnstrand et al.[7] who observed that the roots may contact the sinus across a larger surface area, not limited to the socket's most apical portion. Mesial angulation has been highlighted as a risk factor by other studies [5, 20]. It is noteworthy that teeth with distal angulation were relatively infrequent (n = 11) in our cohort, suggesting the need for further investigation into their significance. The binary logistic regression analysis also identified the loss of mesial contact as a significant OAC risk factor. The presence of a mesial adjacent tooth was associated with a 0.495-fold reduction in OAC risk. This factor is inherently related to mesial angulation and sinus recess on the mesial side; tooth loss can lead to mesialization and sinus pneumatisation over time. The interplay among these factors adds complexity to the analysis.
Our findings advocate for the consideration of various clinical and radiographic indicators on panoramic radiographs when predicting the likelihood of OAC in association with upper tooth extractions. To the best of our knowledge, this is one of the inaugural studies to evaluate the incidence of OAC following tooth extractions using routine panoramic radiographs, with a particular focus beyond the upper wisdom teeth. Our interrater reliability was good to excellent, validating the effectiveness of our predefined criteria and the reliability of the study's results.
Nonetheless, certain limitations of the study warrant mention. Panoramic radiography only allows for semi-standardized settings. Given the retrospective nature of the study, specific clinical data—such as periodontal probing depth surrounding the tooth, tooth mobility, precise localization of OAC within the alveolar socket, or detailed accounts of the instruments used and the difficulty of the extraction procedure—could not be collected. Additionally, the variability in operator technique was not addressed due to the involvement of numerous dentists in the extractions.
While CBCT remains the superior imaging modality for predicting OAC during dental extractions, its use is constrained by cost, radiation exposure, and environmental impact. A prospective clinical study incorporating comprehensive preoperative examinations, meticulously documented interventions, and precise measurements taken from well-aligned periapical radiographs using the parallel technique could yield additional valuable data for the prediction of post-extraction OAC.