A Study of Maxillary Central Incisor Inclination and Projected Tooth Length in Panoramic Radiographs

Hypothesis: It was hypothesized that a significant association exists between maxillary central incisor inclination and the discrepancy between actual tooth length and tooth length measured on a panoramic radiograph. Objective: The purpose of this study was to determine if the discrepancy between the actual maxillary central incisor length measured on a cone beam computed tomograph (CBCT) and the maxillary central incisor length measured on a panoramic radiograph is associated with the tooth’s buccolingual inclination as determined from a lateral cephalogram. Methods: Digital panoramic radiographs, lateral cephalograms, and CBCT scans were taken on thirty-five dry skulls obtained from the University of Illinois at Chicago College of Dentistry. The lateral cephalograms were used to record the maxillary central incisor inclination with respect to two different reference lines, the sella-nasion line (U1SN) and the Frankfort horizontal line (U1FH). The vertical length of the most facially-positioned central incisor was measured on the panoramic and CBCT images of each skull. The differences in maxillary central incisor length from panoramic to CBCT image were recorded (DU1PACT). Correlation testing was conducted to assess if a significant association exists between DU1PACT and U1SN as well as betweetn DU1PACT and U1FH. Results: Significant, positive correlations were found between DU1PACT and U1SN as well as between DU1PACT and U1FH (p<0.05). Conclusions; The cephalometric inclination of the maxillary central incisors in this study were positively associated with the difference between their actual length as determined from a CBCT scan and their lengths determined from a panoramic radiograph. It is suggested that this association be considered in all studies involving tooth length assessment on panoramic images.