New perspectives on the relationship between mandibular and statural growth.

BACKGROUND: Condylar and somatic growth have similar growth curves. The aim of this study was to compare both growth curves in untreated subjects at different ages and investigate if a correlation factor (CF) could be established.

MATERIAL AND METHODS: Semi-longitudinal records (cephalograms and body height) of 418 untreated, healthy children (193 girls and 225 boys) from a craniofacial growth study were analyzed. Incremental changes of three mandibular measurements from articulare and three from condylion were compared to statural growth changes separately. Based on the assumption that mandibular and somatic growth both follow a parallel line, a CF was postulated and checked for validity and reliability.

RESULTS: Mandibular growth spurt could be observed in all six different mandibular measurements, but distances from condylion were more informative. Gonial measurements were not as indicative as symphyseal distances. Mandibular growth did not coincide with somatic growth precisely, and condylar peak velocity preceded statural peak velocity in boys and was slightly delayed in girls. CF was close to the value of 0.4, and its validity could be ascertained when using the condylion-gnathion distance for all ages in girls and up to the age of 12 in boys. Reliability, however, proved to be poor owing to heterogeneity of the sample.

CONCLUSIONS: Although the relationship between mandibular and statural growth increments can be expressed as a CF with some degree of adequacy, the variance rendered CF unreliable. When evaluating growth-related changes, condylion should be preferred as condylar reference, and symphyseal landmarks should be favoured over gonion.