Growth of the Maxilla in Three Dimensions as Revealed Radiographically by the Implant Method

Abstract

By use of the implant method the growth of the maxilla was analysed from profile and frontal (postero-anterior) cephalometric radiographs in nine boys with normal primary occlusion who were followed annually up to adult age without receiving any orthodontic treatment. The proportion of sutural and appositional growth in height was determined from profile radiographs with reference to implants in the infrazygomatic crest. The sutural lowering of the maxillary corpus was, on average, about twice as big as the apposition at the floor of the orbits. The resorptive lowering of the nasal floor amounted to about one-third of the appositional growth in height of the alveolar process. Our study suggests that the contour of the anterior surface of the zygomatic process could be used as a reference structure in growth analysis as this contour kept a constant relation to implants in the infrazygomatic crest and closely followed the natural growth rotation of the maxilla. In relation to the implants, the dentition as a whole drifted forward on the maxillary corpus, simultaneously with a smaller decrease in arch length which was partly related to a differentiated development in width of the maxilla. Measurements between bilateral implants on frontal radiographs proved that the growth in the median suture was greater posteriorly than anteriorly, whereby the two halves of the maxilla rotate in relation to each other in the transverse plane. This was reflected in the development of the dental arch as the increase in the bi-molar width showed a high correlation with the sutural growth posteriorly in the medium suture, while the increase in the bi-canine width was lesser. The forward drift of the dental arch led to a reduction in incisor spacing, which may give rise to an incisal secondary crowding.