Three-dimensional Bolton-Brush Growth Study landmark data: Ontogeny and sexual dimorphism of the Bolton standards cohort

Objective: The treatment of craniofacial reconstructive surgery patients ma y benefit from comparison to average referent three-dimensional landmark da ta. These data may be useful for diagnosis, treatment planning, prosthetic design, or outcomes assessment. With regard to subadult patients, we hypoth esize that the pattern of ontogenetic shape change of same sex, same ethnic ity, referent populations will show gross uniformity. We present a prelimin ary shape analysis of 50 three-dimensional landmarks derived from 317 Bolto n-Brush Growth Study biorthogonal image pairs. We determine which landmarks can be collected from scanned radiographs reliably by four operators for t he precisely locatable points, ontogenetic trends in landmark configuration shape change, and patterns of sexual dimorphism, Participants: Participants were Bolton standards individuals (16 male and 1 6 female) who contributed biplane cephalograms seven or more times with ann ual or greater spacing between ages 3 and 18 years. Design: After removing outliers, we searched far ontogenetic heterogeneity, including sexual dimorphism and within sex-specific Procrustes coordinate shape spaces. Results: A cut-off of 4.3-mm interoperator error left 32 landmarks in our a nalysis. Three different approaches (principal component analysis, age-tren d analysis, and principal components of age residuals) all found no pattern s of individual variation around sex-specific average trends of shape chang e. Male shape change peaks at age 15, a correlate of the growth spurt. Conclusions: Simultaneous frontal and lateral anatomic landmark identificat ion improves three-dimensional localization reliability. Three-dimensional craniodental shape change from ages 8 to 18 within the Bolton standards pre sents little heterogeneity. Considerations of ethnicity aside, these may be initial grounds for use of these data as a normative referent.