A comparison of two- and three-dimensional incisor angles

Two- and three-dimensional incisor angulations are compared in 40 patients using lateral radiographs and direct dental cast measurement using the Reflex Metrograph coupled to a computer. The two-dimensional upper and lower incisor angulations to the occlusal plane were also compared by the two methods. It was found that: The two-dimensional radiographic and three-dimensional dental cast inter-incisor angulation showed a significant difference at a probability level 0.01 greater than p greater than 0.001. The two-dimensional radiographic and two-dimensional dental cast upper left and right incisor angulations to the functional occlusal plane showed a significant difference at a probability level of 0.01 greater than p greater than 0.001. The significant differences can be attributed to the measurement of the incisor crown angulation in the dental cast measurement and the incisor tip and apex assessment in the radiographic technique. The system of dental cast measurement arguably provides a more realistic and reliable assessment of incisal angles than conventional radiographic measurement techniques.