Читать книгу Bone and Soft Tissue Augmentation in Implantology - Группа авторов - Страница 54

In the semi-axial skull radiograph pa (posterior– anterior beam direction), the skull is partially imaged and, when correctly positioned, allows for the superimposed representation of the zygomatic bone and the maxillary sinus. This image allows for the evaluation of the transverse extent of the antrum. In addition, in a side-by-side comparison, it provides information on the presence of foreign bodies or any sinus pathology. The image is taken at maximum mouth opening, whereby the horizontally guided central x-ray beam enters about 10 cm above the external occipital protuberance and leaves the skull at the spina nasalis (Fig 2-15).

Fig 2-15 Paranasal sinus radiograph with an implant in the maxillary left sinus.

Lateral skull imaging with a laterocentral beam through the sellar region is used at a distance of > 1.5 m as a lateral cephalogram, essentially for cephalometry in orthodontic treatment. For implant planning, this image can impart important information about the sagittal position of the maxilla and mandible as well as the inclination of the incisors and the orientation of the anterior ridge. By showing the contour of the removable prosthesis with tin foil, the degree of atrophy in relation to the necessary prosthetic reconstruction can be determined.

When bone harvesting from the chin is planned, this type of radiograph is useful to preoperatively determine the form and volume of the bone in the symphysis area as well as the amount of bone healing that occurs postoperatively (Fig 2-16a to c).

Fig 2-16a Cephalometric radiograph for determining the available bone in the chin area: progenic position of the mandible due to the atrophy of the maxilla.

Fig 2-16b Control radiograph after implant placement and bone harvesting from the chin area, which was covered with a titanium membrane (see also Chapter 4). Due to the grafting of the maxilla and the implant placement in the mandible, the sagittal step could be significantly reduced.

Fig 2-16c Control image 10 years postoperatively with well-regenerated donor site.