Radiographic Examination General Issues
Radiography is critical to determine several things.
- Bone quality and quantity (height and width) allows the surgeon to determine how much bone is available in the proposed implant site. Good bone quality and quantity are necessary for immediate implant therapy success.
- Determining the long axis of the alveolar bone allows the surgeon to optimize the trajectory of implant placement with the emergence profile and loading characteristics of the implant.
- It helps to identify and localize important internal landmarks and anticipate and prevent surgical accidents: mandibular canal, maxillary sinus, nasal fossa, mental foramen, incisive canal, etc.
- The jaw shape and size, and jaw boundaries (including fossae), constitute the limits of the operation.
- Pathology such as retained roots tips, inflammatory processes, cysts and tumors can be detected.
The diagnostic information and treatment planning gained during image analysis needs to be shared with the patient and the restorative dentist.
There are different types of radiological examination, as follows.
Types of Examination
A panoramic exposure could be interesting in order to measure the available vertical bone length and the distance to important anatomical landmarks, but no information about bone width and long axis or ridge are provided.
Usually, a spiral computed tomography (CT) scan is not necessary since the height and width of the bone crest is maintained by the neighboring roots; but cone-beam computed tomography (CBCT) is especially useful because of its higher resolution and lower radiation, when working close to the inferior alveolar nerve (as in the mandibular second premolar extraction case), and when the clinical exam indicates a small volume of bone (iatrogenically destroyed by infection or the natural close relationships of maxillary molars with the maxillary sinus).
The minimum bone volume required for implant surgery is about 7-9 mm of height measured from the level where the jaw is at least 4-6 mm wide. Mesiodistally, a minimum of 7 mm is necessary.
Well-orientated intraoral radiographs can be used for measuring the mesiodistal distance between neighboring roots or important anatomical landmarks, and to elucidate whether there is a periapical or proximal infrabony bone defect.