title: The reliability of the Frankfort Horizontal in roentgenographic cephalometry.
abstract: This longitudinal investigation was undertaken to assess the reliability of the Frankfort Horizontal line (FH) when using either anatomical Porion (Po-a) or machine Porion (Po-m) as reference landmarks. Lateral head films (22 pairs) from subjects at the ages of 11 and 14 years were analysed twice. The results revealed that: (i) the registration error of Po-a was larger than of Po-m; (ii) for Po-a the registration error from the 11 year head films was approximately twice as large as from the 14 year head films; (iii) Po-m was, on average, located approximately 9 mm below and 2 mm anterior to Po-a; (iv) during the 3 years of observation, Po-m changed its position downward markedly more than Po-a; (v) due to the diverging location of machine Porion (Po-m) in relation to true Porion (Po-a) and the large change of Po-m with time, the FH was affected considerably. It was concluded that machine Porion was unsuitable for the construction of the FH. A misjudgement of the reference line may result in diagnostic misinterpretations and lead to false conclusions in longitudinal studies, e.g. when the outcome of a particular treatment procedure is evaluated.
authors.affiliation: Department of Orthodontics, University of Giessen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Pancherz
authors.forename: K
authors.initials: K
authors.lastname: Gökbuget
mesh_terms: D000202:Activator Appliances; D000293:Adolescent; D002508:Cephalometry / Q000379:methods*; D002648:Child; D005145:Face / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007574:Jaw Relation Record; D008137:Longitudinal Studies; D008297:Male; D009972:Orthodontics, Interceptive; D017063:Outcome Assessment, Health Care; D012016:Reference Values; D015203:Reproducibility of Results