LANDMARK IDENTIFICATION ERROR IN SUBMENTOVERTEX CEPHALOMETRICS - A COMPUTERIZED METHOD FOR DETERMINING THE CONDYLAR LONG AXIS

The purpose of this study was to examine the identification error of c ertain submentovertex landmarks and to compare three different methods of determining horizontal condylar angulation in submentovertex radio graphs. To determine landmark identification error, a random sampling of 12 submentovertex radiographs from preorthodontic patients between the ages of 10 and 17 years was used to determine both intraexaminer a nd interexaminer reliability. The error associated with the identifica tion of each of 11 landmarks varied between specific landmarks, betwee n the same landmarks bilaterally, and between the vertical and horizon tal components of the same landmark. In general, intraexaminer data sh owed less landmark identification error in both vertical and horizonta l directions than did interexaminer data. The foramen spinosum landmar ks demonstrated the lowest identification error in both horizontal and vertical directions (intraexaminer), whereas greater identification e rror was associated with the condylar lateral poles and posterior cond ylar points (both intraexaminer and interexaminer). A comparison of th ree different methods of condylar angulation determination was underta ken through the use of two tracings of each of 101 submentovertex radi ographs. A computer-derived method representing the principal axis of minimum moment of inertia of the condyle was shown to be more reliable (p < 0.05) with respect to describing condylar angulation than both a method that used a best-fit line through the anterior condylar border and an interpolar axis method.