Diagnostic imaging overview
- Diagnostic imaging is often an essential element in oral rehabilitation for a missing single tooth.
- Intra-oral imaging is often sufficient to establish a proper evaluation of the bone and neighbouring teeth.
- Cross-sectional imaging may be relevant to assess remaining bone volume and anatomical landmarks in the vicinity.
- Three-dimensional imaging opened the possibility for preoperative implant planning and guided surgery.
Diagnostic imaging is an important element of the treatment planning in oral rehabilitation of a missing single tooth.
There should be no imaging prior to a thorough clinical examination. One should consider cost and radiation issues prior to choosing the appropriate imaging technique. When a removable denture is planned to replace a missing single tooth, there is no apparent justification to radiograph the edentulous space in the absence of clinical signs or symptoms. When a fixed denture is planned intra-oral radiographs of the abutment teeth should be taken to assess the periapical region and dental and periodontal structures. Using supplementary cross-sectional imaging should only be done after conventional radiography has been evaluated and judged insufficient. Spiral computerized tomography (CT) leads to an increased radiation vs. cone beam CT (CBCT).
The greatest benefits of the 3D imaging are:
- the ability to analyze the anatomy of the patient’s jaw volume before surgery,
- identify vital structures, such as adjacent root positions, nerve canal, sinus wall, cortical borders,
- being free from errors introduced by poorly positioned films,
- the placement of implants without bone grafting, like tilted implants or short implants.
The 3D visualization of the features of implant recipient sites and anatomy often influences the surgical and prosthetic decision making.
Figures 1 & 2: CT scans taken before (left) and after (right) implant placement and guided bone reconstruction.
Computer-assisted template-based implant planning and placement require the need for cross-sectional imaging.
Most guided surgery systems also allow the visualization of the desired restorative outcome, in the form of a diagnostic tooth setup that is scanned and displayed fully correlated with the scan of the anatomy. This empowers the ideal placement from both bone and prosthetic considerations.
Guided-surgery opened the possibility for preoperative implant planning and proper communication with the patient, surgeon and the prosthodontist. One of the main advantages of computer-guided rehabilitation is less postoperative pain and swelling but such advantage could require higher biological cost. Medical exposure to ionizing radiation and associated risks must always be considered and result in a net benefit to the patient.
Figures 3-6: 3D implant planning and cross-sectional view (left 3 images), Surgical Guide (right)
The choice of the specific imaging technique appropriate for a given patient depends on the case, the different stage of treatment, and last but not least, the clinicians’ experience. However, the As Low As Reasonably Achievable (ALARA) principle must also be applied, taking into account any alternative techniques that might achieve the same diagnostic information required by the dental team.