Morphologic evaluation of the incisive canal and its proximity to the maxillary central incisors using computed tomography images

Abstract

Objective: To evaluate the morphologic features and the relative position of the incisive canal with regard to the maxillary incisor roots using computed tomography (CT). Materials and Methods: Morphologic evaluation of the incisive canal and its proximity to the maxillary central incisors were measured using CT images of 38 adults with skeletal and dental class I normal occlusion. Linear measurements were performed on the axial cross-sectional images corresponding to three vertical levels, the palatal opening of the incisive canal (L1), midlevel between the opening level and the root apex of the maxillary central incisors (L2), and the root apex of the maxillary central incisors (L3). Results: The percentage of subjects with an incisive canal width greater than the interroot distance of the central incisors was 86.8% and 63.2% at levels L1 and L2, respectively. The anteroposterior distance between the maxillary incisor roots and the boarder of the incisive canal was approximately 5-6 mm at levels L1 and L2. Conclusion: The anteroposterior distance between the maxillary central incisor roots and the incisive canal was approximately 5-6 mm. More than 60% of the subjects had an incisive canal width greater than the interroot distance. Evaluation of the proximity of the incisive canal to the maxillary incisors, along with its dimensional characteristics, may be helpful when a considerable amount of maxillary retraction is planned. (Angle Orthod. 2016;86:571-576.)

Contact of the incisive canal and upper central incisors causing root resorption after retraction with orthodontic mini-implants: A CBCT study

“…IC width in this study was similar to that in the study of Zhou et al 20 and slightly larger than that in the study of Cho et al, 11 possibly due to the different selection of measurement levels. Although IC width was not found to be a risk factor in the current study, an excessively wide IC should also be a warning for increased risk because Cho et al 11 found a wider IC than inter-root distance in over 60% of subjects.…”

“…7 It was emphasized in prosthodontics and oral implantology that image diagnoses should be conducted before restoration 7 but, in orthodontics, few studies have paid attention to the approximation of U1 and the IC. 11 In past studies, the opening of the IC (the incisive foramen) was defined as the lowest point of the palatal wall. 9,11 However, in the present investigation, it was found that the concavity could be seen at the lowest point of the buccal wall.…”

“…11 In past studies, the opening of the IC (the incisive foramen) was defined as the lowest point of the palatal wall. 9,11 However, in the present investigation, it was found that the concavity could be seen at the lowest point of the buccal wall. Therefore, the horizontal levels selected in this study were more incisal relative to U1s than in past studies.…”

“…However, since it is very difficult to set a standard definition for the shortest distance from U1 roots to the IC, anteroposterior distances were used. 11 In the current study, measurements were conducted at three horizontal levels because the root apex and tooth neck could move in opposite directions. For example, at L3, an increased U1-IC distance was found in some of the patients, implying buccal movement of the root apex, which could also explain the statistically insignificant difference between the contact and noncontact groups.…”

“…Chung et al 10 noticed in two cases that in conducting en masse retraction with the help of orthodontic miniimplants, the root of one of the U1 made direct contact with the cortical plate of the IC and extensive root resorption was observed. Cho et al 11 analyzed the proximity of U1 and the IC using computed tomography and found the IC width larger than the inter-root distance in more than 60% of subjects and that the ''safety zone'' of orthodontic retraction was smaller than previously believed.…”