Association between cranial structure and choice of bolus hardness in an orthodontic sample

To assess whether craniofacial morphology and vertical growth patterns are associated with a preference for hard or soft alimentary boluses in a sample of orthodontic patients.

This cross-sectional study included 121 orthodontic patients (69 females, 52 males; mean age = 12.3 ± 3.3 years). Before-treatment, lateral skull x-rays were collected and lateral cephalometric analysis performed, considering variables SpP^GoGn, SN^GoGn, SpP^CoOr, and AN^B. Before undergoing chewing pattern analysis, each patient was asked to chew a standardized soft bolus (chewing gum) and subsequently a standardized hard bolus (wine gum) in a flavor of their choice. Subsequently, each patient was asked to express a preference for one of the two boluses, and the answer was recorded. To assess the association between bolus hardness preference and cephalometric variables, multiple linear regression analyses were performed, controlling for sex and age.

Soft bolus was preferred by 64% of subjects (n = 77) and hard bolus by 36% (n = 44). Increased SpP^GoGn angle was significantly associated with soft-bolus preference (P <.05) as well as being female but was independent of age. SN^GoGn increased with age (P <.05) but did not correlate with bolus preference or sex. No significant associations were observed for SpP^CoOr and AN^B.

Soft bolus preference was significantly associated with increased intermaxillary divergence but not with cranial divergence, mandibular rotation, or sagittal skeletal relationship. These findings suggest that patients with intermaxillary hyperdivergent patterns may self-select softer boluses, due to a compensatory functional-structural feedback loop.