OBJECTIVE: To determine the shape and dimensions of the nasopalatine canal (NPC) from a bank of cone beam computer tomographic (CBCT) scans in a university setting. Utilizing virtual implant planning software, determine the frequency of implant invasion into the NPC, and analyze the relationship between invasion and the various shapes of the NPC in both the sagittal and coronal slices. The relationship between age, gender, ethnicity, and incisor status will be considered in the analyses.

MATERIALS AND METHODS: CBCTs of 201 patients were evaluated retrospectively. The shapes were evaluated in the sagittal and coronal views. The length and widths were measured on the sagittal section, and the volume measured in the axial, sagittal, and coronal views. Implants were then placed in an ideal restorative position based on either the patient's existing tooth, a virtual tooth, or an overdenture dual scan. Implant invasion into the canal was measured. If an implant did not invade into the canal, then the distance from the NPC to the implant was measured.

RESULTS: The coronal shapes, from highest to lowest frequency, were single, then y-shaped then two parallel canals. The curved and straight sagittal shapes were equally frequent, and the hourglass shape was least common. The mean length of the canal was 13.1 mm. The oral, middle, and nasal widths were 4.8 mm, 2.4 mm, and 2.9 mm, respectively. The overall volume was 0.12cc. All dimensions were larger in males than in females. As age increased, the middle width increased and the volume increased. Implant invasion occurred 30% of the time. Shorter length and wider canals at the oral-nasal center location, as well as missing incisors, were associated with implant invasion. The non-invading implants were on average 1.5 mm away from the NPC.

CONCLUSIONS: The frequency of implant invasion was 30%, which was related to number of incisors present, short length, and wider canal. The mean length was 13.1 mm. The oral width was on average widest, followed by the nasal and then the middle width. Gender impacted all dimensions, and age impacted the middle width and volume.