A re-investigation of the relationship between head posture and craniofacial growth.

This investigation was designed to repeat classic studies into the associations between head posture and growth as a single unified study using up-dated methods for gathering and analysing the data. The material comprised the cephalometric radiographs of 59 children (34 males and 25 females) recorded in natural head posture (self-balance position), at the beginning and end of a period of observation during which no treatment was performed (mean age at initial radiograph 11.76 years, mean interval between radiographs 3.52 years). Correlation analysis (corrected for multiple inference and adjusted for dependency between the variables) showed the strongest associations to be between growth direction of the face and the change in posture. No association was found between growth (direction or magnitude) and pre-observation posture. The most prominent associations were between the change in cranio-cervical posture (CCP) and variables representing the growth directions of the mandible (r = 0.72, P < 0.0001); anterior maxilla (r = 0.49, P < 0.001); posterior cranial base (r = 0.45, P < 0.01); temporomandibular joint (r = 0.56, P < 0.001); and the change in postural height of the tongue (r = 0.54, P < 0.0001). These findings do not support the hypothesis of a causal relationship between initial posture and subsequent facial growth. Instead, they indicate that it is the change in posture that is primarily linked to the growth direction of the face. The patterning of the correlations and the inter-relationships between the main growth variables suggest that this linkage arises from the coordinated changes that occur in the postures of the mandible and tongue. These coordinated postural changes appear to determine the growth direction of the mandible and, at the same time, influence CCP, possibly via an effect on pharyngeal patency.