Can 'articulare' be used in the cephalometric analysis of mandibular length? A methodologic study.

Abstract

The aim of this investigation was to ascertain whether in longitudinal studies ‘articulare’ could be used as a substitute for various condylar landmarks in mandibular length measurements on centric occlusion lateral head films, thus avoiding additional mouth open roentgenograms for condylar survey. Profile roentgenograms of 40 boys (aged Mean = 12.1 years, s.d. = 1.1 years) with a Class II, division 1 malocclusion were analysed before and three and a half years after orthodontic treatment (at least one year after retention). Centric occlusion and mouth open lateral head films were analysed. Mandibular length measurements from pogonion (pg) to three defined condylar landmarks (condylion co, condylion superior cos and condylion posterior cop) and to articulare (ar) were compared. Irrespective of the variable used, mandibular length increased by an average of 11 mm during the examination period. Wide individual variations were found in mandibular length measurements for differences pg-condylar landmarks and pg-ar. The average difference between pg-co and pg-ar was 6.3 mm (s.d. = 2.6 mm) with a minimum of 1 mm and a maximum of 12 mm. The average differences were the same before and three and a half years after orthodontic treatment. However, the individual difference in pg-co and pg-ar lengths varied considerably—in 10 percent of the subjects it was greater than 2 mm. Thus in longitudinal studies of ‘individual cases’ condylar landmarks should be used in the analysis of mandibular length. Mouth open lateral headfilms would be needed to visualize the condyle for accurate measurements. In longitudinal studies comparing ‘groups of subjects’ on the other hand ‘articulare’ may be used as a substitute of various condylar landmarks in the analysis of mandibular length on centric occlusion lateral head films.