Cráneos peruanos con deformación intencionadaun estudio morfométrico a partir de tele-radiografía lateral

Resumo

Craniofacial development is a highly complex process that involves a hierarchical interaction between different morphological units. Although these structures exhibit a degree of independence, they do have close functional and developmental interdependence. The intimate relationship between the development of the cranial base and the growth of the nasomaxillary complex is widely accepted; more controversial, however, is the possible relationship between mandibular prognathism and changes to the cranial base, with a more protrusive position of the mandible when the glenoid fossa is in a more anterior position. Skulls with artificial morphological modification, produced by deformation of the vault for cultural reasons, are a source of very relevant information about the interactions between the cranial vault, the cranial base and the viscerocranium. Despite their apparent heterogeneity, these skulls form a sample that permits us to the study the interaction between normal growth patterns and permanent deformation. The objective of this study was to investigate the morphological relationship between these three anatomical units (cranial base, mandible and nasomaxillary complex) in skulls subjected to two different methods of intentional deformation (ADC). Lateral x-rays of the skull and face were used to perform a morphological study using geometric morphometry and classical multivariate cephalometry. The skulls were divided into three groups: 32 with antero-posterior (AP) cranial vault deformation, 17 with circumferential vault deformation (C) and 39 with no apparent deformity. The skulls were of Amerindian origin from the Andean coastal region of Peru, from a period prior to contact with Europeans. Deformation of the vault was found to have a marked effect on the cranial base. Alterations were also observed in the structures of the viscerocranium, with changes in the nasomaxillary complex resulting from the modification of development (in the AP skulls), and alterations of the roof of the orbit secondary to rotation of the anterior cranial fossa, with anterior nasal displacement. Prognathism observed was observed in both types of deformation (AP and C), at the expense of the alveolar process. Skulls with circumferential deformation showed rotation of the maxilla and displacement of the orbit. AP deformation was associated with ante-rotation of the structures of the malar region. The posterior facial plane was shown to be an axial structure that serves as an interface between the middle cranial base and the nasomaxillary complex. The mandible is also affected by cranial deformation: narrowing and elongation of the mandibular ramus were detected, with rotation of the body of mandible and an increased mandibular anterior height, all of which were associated with a dento-alveolar compensation process. The degree of anterior mandibular displacement did not mirror the anterior displacement of the middle cranial fossa. The specific effects of intentional cranial deformation on the mandible support the hypothesis that mandibular prognathism is of multifactorial origin and, although the mandible is closely integrated with the cranial base, there are many other factors that can neutralize the direct effect of the anterior displacement of the cranial base. The classical multivariate cephalometry study confirmed the morphological changes and structural (angular) changes of a general nature, but did not permit a detailed study of the behaviour of certain structures in each type of deformation.