The purpose of this study was determine the interexaminer tracing and digitizing repeatibility for computer aided lateral cephalometric measurements. The material used in this study comprised 60 lateral cephalometric radiograps (20 Class 1, 20 Class 2, 20 Class 3). Four examiners traced all radiograps and digitized 134 landmarks by using RMO joe version 5 Package program. In this program 51 measurements were selected. To evaluate statistically the differences between the examiners repeatability degrees were calculated in a PC program made in BASIC for all parameters. SN, SNB, SND, ANB, Ramus height, GnGoAr, MGoS, GoM, SL, Palatal/Mandibuler plane angle, SN/GoGn, Anterior and posterior face heights, MeANS, Lower facial height, Total facial height, SNPg, Y axis, L1NB degree, L1/Mandibular plane, Overjet, Lower lip/esthetic plane and H angle demonstrated high repeatability (r>0.900). Ramus Xi position had very low repeatability degree (r=0.329). Repeatability degrees for maxillary height, Occlusal plane/SN, L1 extrusion and nasolabial angle changed among 0.600-0.700.

Keywords: Repeatibility, measurement, tracing error