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Abstract Background The purpose of the present study was to describe the CT imaging findings of normal incisive canals and incisive canal cysts and propose cut-off values to differentiate between them. Methods A total of 220 normal subjects and 40 patients with incisive canal cysts on multi-detector row computed tomography (MDCT) were retrospectively analyzed. The shapes, sizes, anatomic variations, Hounsfield scale values, and so on of maxillary incisive canals and the sizes and Hounsfield scale values of maxillary incisive canal cysts were analyzed. Results A significant difference in sizes of maxillary incisive canals in normal subjects was found between males and females. The sizes of maxillary incisive canals were significantly wider during aging, but shapes, anatomic variations, and Hounsfield scale values in the maxillary incisive canals were not significantly different with aging. A significant difference in sizes but not Hounsfield scale values was found between normal maxillary incisive canals and maxillary incisive canal cysts. Based on a cut-off of over 6 mm in the width of incisive canals, maxillary incisive canal cysts could not be appropriately diagnosed for subjects over 60 years of age. Over 60 years of age, maxillary incisive canal cysts could be appropriately diagnosed based on a cut-off of over 7.1 mm in width of incisive canals. When maxillary incisive canals of the hourglass types were seen on sagittal sections, significantly more patients had maxillary incisive canal cysts than other types. Conclusion In coincidentally diagnosing asymptomatic incisive canal cysts on imaging, we should apply different cut-offs for the size of the maxillary incisive canal for patients over and under 60 years of age. Specifically, the cut-offs for the long axis of maxillary incisive canal cysts were 7.1 mm for patients over 60 years of age and 6.0 mm for those under 60 years of age. In addition, we should pay attention to wider canals with hourglass shapes as indicative of cystic change of maxillary incisive canals.

Objectives The purpose of the present study was to elucidate the significance of cone bean computed tomography (CBCT) for patients hoping to undergo implant-supported restorations of the maxilla. Therefore, two studies were planned. One was to compare the prevalence of anatomic variations and lesions in the maxillary sinus on CBCT of patients hoping to undergo implant-supported restorations of the maxilla with that in patients with other chief complaints in a private dental office in Japan. The other study was to elucidate the limitations of panoramic radiographs in the detection of anatomic variations and lesions in the maxillary sinus. Study design Sixty-one pairs of panoramic radiographs and CBCT were retrospectively analyzed in two groups of patients, those who hoped to undergo implant-supported restorations in the maxilla (Implant group) and those who did not (Non-implant group). The presence of anatomic variations and lesions in the maxillary sinus were analyzed. Results The detection rate of mucosal thickening was significantly higher in the Implant group than in the Non-implant group. The detection rates for the features analyzed were significantly lower on panoramic radiographs. In particular, the detection rates of internal and anterior locations of some features were noticeably lower on panoramic radiographs. A significant relationship was found between the change in the detection rate on panoramic radiographs and the widths of mucosal thickening or the lengths of the major axis of SOLs in the maxillary sinus. If the width of mucosal thickening or the length of the major axis of SOLs was <3 mm or <4 mm, respectively, the detection rate on panoramic radiographs was significantly decreased. Conclusion CBCT is important for patients hoping to undergo implant-supported restorations of the maxilla because of the mucosal thickening in the maxillary sinus in such patients and their lower detection rates on panoramic radiographs. [ABSTRACT FROM AUTHOR]