Bienias, Russell2018-11-282018-11-282018-08https://hdl.handle.net/11299/201019University of Minnesota M.S. thesis.August 2018. Major: Dentistry. Advisor: Scott McClanahan. 1 computer file (PDF); ix, 103 pages.Purpose: The purpose of this study was to complete a comprehensive CBCT analysis of Vertucci Type III mandibular incisors to aid clinicians in the understanding of the complex morphology in these teeth and developing strategies to prevent endodontically related failures. Materials and Methods: 100 mandibular incisors were used in this study with selection criteria being easily distinguishable, untreated, no root caries/resorption, no CEJ caries/resorption, no fractures, and with a Vertucci Type III canal system. Parameters were set at 68 kV, 2.0 mA and 76 um using the Kodak CareStream9000 3D LFOV CBCT (CareStream Dental LLC, Atlanta, GA). Measurements were made using the Kodak CareStream software with the goal to determine the safest approach for NSRCT for Vertucci Type III mandibular incisors and provide treatment guidelines and which rotary instruments may be safest. Discussion of possible “Danger Zone” is analyzed as well. Results: Clinically significant measurement data was found on mandibular incisors for mesial distal and facial lingual dimensions, CEJ to Pre-Split and Join, Apex to Pre-Split and Join, root length, and Inter-Canal dentin between the facial and lingual canal. The average shortest distances from the canals to the external surfaces at the Pre-Split, Inter-Canal, and Join axial slices was collected. The mean angles of deviation for Pre-Split facial, Pre-Split lingual were clinically found similar and Join facial and Join lingual measurements were also found similar. Straight-line access was found to be 94% through the incisal and 6% to the facial. If using ≤ 0.3 mm remaining radicular dentin as the fracture risk parameter, preparation of the root canal system with 25/04 to 50/04 and ProTaper Gold F1-F3 rotary instruments is acceptable. If using ≤ 0.5 mm remaining radicular dentin as the fracture risk parameter, rotary files > 35/04 and ProTaper Gold F1-F4 are not recommended. Conclusion: The distal concavity is considered a “Danger Zone” beginning with where the canals split/bifurcate and continued apically. Mandibular incisors with Vertucci Type III anatomy are complex and present challenges for treatment. Based on the findings of this study clinical recommendations are offered and discussed to help achieve clinical success.enThesis or Dissertation