orbito-condylion and orbito-basion lines as alternatives to frankfurt and sella- nasion lines in cephalometry

Aim: frankfurt horizontal and sella-nasion lines are the most widely accepted and used landmarks in cephalometric analysis. this study investigates the use of the orbito-condylion line extending from the orbitale to the condylion as a novel horizontal line for substituting the frankfurt horizontal line. similarly, the evaluation of the orbito-basion line as an alternative to the sella-nasion line in cephalometric analysis was done. we evaluated the reproducibility of the new horizontal lines and measured the angle between the orbito-condylion line and the frankfurt line; and the angle between the sella-nasion and orbitale-basion line.methods: this investigation was carried out on 30 individuals. the porion, orbitale, condylion, sella, nasion, and basion were identified and marked. the angles between the orbito-meatal line (inferior orbital rim to the porion; the frankfurt line) and the orbito-condylion line (inferior orbital rim to the condylion) were measured. likewise, the angles between the sella-nasion line (center of sella tursica to nasion) and the orbito-basion line (inferior orbital rim to basion) were measured.results: significant interobserver and intraobserver bias did not exist. the mean angle between the frankfurt line and orbito-condylion line was 0.5°±2.27° and the mean angle between the sella-nasion line and orbito-basion line was 3.48°±3.11°.conclusion: this study showed the new lines have good reproducibility, reliability, and efficacy. the orbito-condylion and orbito-basion lines are reliable, reproducible, and easily identifiable, and has the potential as novel standard horizontal lines to supersede or complement the frankfurt line and sella-nasion line in anthropological studies and clinical applications.