Читать книгу Bone and Soft Tissue Augmentation in Implantology - Группа авторов - Страница 57

When using any radiologic technique, the benefit and risk of ionizing exposure should be calculated.^1,2 Therefore, depending on the type of device, whether spiral CT or CBCT, with or without image intensifier technology, the indication can be limited or passed on.^21,72 Before a CBCT scan is taken, a clinical examination and evaluation of the available radiograph images is necessary to ensure that the patient will have a diagnostic or therapeutic benefit greater than the potential hazard from radiation exposure. It should also be considered that the risk of radiation hazard in children is three times greater than in adults, although most patients requiring bone graft surgery are over 50 years of age, at which age the relative risk decreases to 30% to 50% compared with a 30-year-old patient.²³

It has been shown that in more than 40% of patients, a mostly asymptomatic change in the maxillary sinus mucosa (e.g. swelling, mucocele) is present. The prevalence of at least one septum is 46.8% per patient⁶⁷ (Fig 2-19d). Three-dimensional diagnostics can be used to explore areas of undercut on the lingual side of the mandible that are not detectable on a panoramic radiograph (Fig 2-19e). This avoids lingual perforations during implant bed preparation (Fig 2-19f).

The evaluation of the retromolar triangle has shown that the thickness of the buccal cortical structure is approximately 3 to 4 mm. The location of the mandibular canal in moderately atrophied jaws is usually > 10 mm under the alveolar crest, so that sufficient bone is normally available for the harvesting procedure. However, it was also found that in 10.2% of cases, the nerve was very superficial to the buccal site, with very close contact with the vestibular cortical bone plate, which requires a very careful approach for bone harvesting.⁶³