Composite growth model applied to human oral and pharyngeal structures and identifying the contribution of growth types

Abstract

The growth patterns of different anatomic structures in the human body vary in terms of growth amount over time, growth rate and growth periods. The oral and pharyngeal structures, also known as vocal tract structures, are housed in the craniofacial complex where the cranium/brain follows a distinct neural growth pattern, and the face follows a distinct somatic or skeletal growth pattern. Thus, it is reasonable to expect the oral and pharyngeal structures to follow a combined or mixed growth pattern. Existing parametric growth models are limited in that they are mainly focused on modeling one particular type of growth pattern. In this paper, we propose a novel composite growth model using neural and somatic baseline curves to fit the combined growth pattern of select vocal tract structures. The method can also determine the overall percent contribution of each of the growth types.

Cervical vertebral body growth and emergence of sexual dimorphism: a developmental study using computed tomography

“…To quantify the growth type (neural vs. somatic) of each of the cervical vertebral bodies, we applied a composite growth model to the geometric growth areas (Wang et al. ). Findings of the percentage of similarity to neural and somatic growth types for each cervical vertebra are summarized in Table .…”

“…The five female (F) cases and three male (M) cases that had measurements for one vertebral body over 2.567 standard deviations away from the fit were identified as outliers (Wang et al. ) and were excluded from all analyses. The data from the remaining 115 cases (45 females and 70 males) were refitted with the fourth‐degree polynomial fit and plotted with a second y ‐axis for percentage of adult growth, an important reference to have when assessing for growth type (neural or somatic; Fig.…”

“…To determine growth type (neural vs. somatic) quantitatively, a composite growth model comprising a linear combination of neural and somatic growth types (Wang et al. ) was applied to the geometric areas to calculate the percentage contribution of somatic and neural growth types towards the overall geometric area growth trends.…”

Characterizing mandibular growth using three-dimensional imaging techniques and anatomic landmarks

“…Furthermore, while the fourth degree mixed-effect polynomial fit and its derivative provided a good overview of developmental trend and growth rate, insufficient data and/or data variability at the extreme age range examined can exacerbate the limitation of this approach, where some measurements (e.g., endomolare width in males) briefly displayed negative growth rates at the lower and upper ends of the age range. The application of a composite growth model, as outlined by Wang et al(2016), will likely overcome this limitation of the fourth-degree mixed-effect polynomial fit. Additionally, rendering developmental 3DCT mandible models can be used to quantify surface area growth in all planes (Chung, Qiu, Seo, & Vorperian, 2015).…”

“…For variables with missing measurements, the missing data treatment entailed using the mean values of its sex-specific fixed-effects fourth order polynomial to impute the values. Next, taking into account measurement from the same subject, the sex-specific measurements for each of the nine variables were fitted with a mixed-effects fourth-degree polynomial model(Wang, Chung, & Vorperian, 2016) . Unlike the fixed-effect model, the mixed-effect model takes into account the dependency among longitudinal data from the same subject and thus provides a better fit to the data than the fixed-effect model.…”