The Use of Lipiodol in Spiral Tomography for Dental Implant Imaging

The Use of Lipiodol in Spiral Tomography for Dental Implant Imaging
Implant Dentistry: Volume 12(1) March 2003 pp 35-40
Siu, Adam S. C. BDS, MDS*; Li, Thomas K. L. BDS, MSc**; Chu, Frederick C. S. BDS(Hons), MSc***; Comfort, Margaret B. BDS, MScÇƒÜ; Chow, T. W. BDS, MSc, PhDÇƒ?
*Honorary Clinical Assistant Professor, Faculty of Dentistry, The University of Hong Kong.
**Assistant Professor, Faculty of Dentistry, The University of Hong Kong.
***Assistant Professor, Faculty of Dentistry, The University of Hong Kong.
ÇƒÜAssociate Professor, Faculty of Dentistry, The University of Hong Kong.
Çƒ?Associate Professor, Faculty of Dentistry, The University of Hong Kong.
Lippincott Williams & Wilkins
Abstract
Preoperative radiographic assessment is mandatory for the meticulous treatment planning and successful placement of implants. The precise topographical evaluation of selected implant sites, apart from the most straightforward cases, requires tomographic examination with the use of diagnostic radiographic templates. The incorporation of various radiopaque materials such as barium sulphate and lead foil as radiographic markers had not been entirely satisfactory. A new contrast medium, Lipiodol ethiodized oil (Laboratoire Guerbet, Paris, France), can easily be mixed with the monomer of autopolymerizing acrylic resin. The resultant acrylic template has several advantages. The tomographic images (Scanora; Soredex Orion Corporation, Helsinki, Finland) are radiographically homogenous and show the contour of the future prosthesis, the angulation of the planned implant, and the thickness of the soft tissue. In addition, the radiopaque template is optically transparent (with a slight yellow tint), which facilitates good visibility of surgical sites when the template is modified to become the surgical guide for implant placement. This transparent template can be further modified for implant position registration at the time of surgery. Because this multipurpose template is simple to construct and inexpensive, it can be recommended for routine use in implant dentistry.
The placement of dental implants requires meticulous planning and careful surgical procedures. The pretreatment evaluation and guidance by the restorative dentist and the placement of the implants by a surgeon are not solely determined by the anatomy of the patient. Presurgical radiographic information provides the multidisciplinary implant team with more comprehensive diagnosis and treatment. 1
The combination of a limited bone volume and poor bone quality leads to less predictable bone apposition and early implant failures. 2 There is a need for a thorough radiographic assessment to evaluate these factors so that patients can be informed of their individual prospects for successful rehabilitation by means of endosseous implants. 3,4
Standard screening radiographs such as panoramic and periapical radiographs enable the clinician to gain a general overview of dental and alveolar status and an initial assessment of the possibility and difficulties of the placement of dental implants at potential implant sites. However, these two-dimensional images give no information about the buccolingual cross-section of the potential implant sites. 5,6 More sophisticated radiographic techniques such as computerized tomography or spiral tomography (Scanora; Soredex Orion Corporation, Helsinki, Finland) are required to depict the alveolar bone in the third dimension and allow for the characterization of the alveolar crest and visualization of anatomical structures in a buccolingual dimension. 7-9
Spiral tomography, Scanora, is a multimodal imaging system that incorporates two imaging principles in one unit: narrow beam radiography and optimized spiral tomography. It produces images of slices or layers of the body by using motions of the x-ray tube and film during an exposure to blur the unwanted body parts. Scanora gives optimal cross-sectional tomograms with low radiation exposure. 10
The precise three-dimensional evaluation of potential implant sites by more advancedradiographic techniques is only possible with appropriate prosthetic templates that outline the planned restoration. 11 It is necessary for the clinician to visualize the final prosthetic result before implant placement. Hard and soft tissues are shown in relation to the planned restoration, and the need for augmentation can be clearly diagnosed before surgery. In addition, the soft tissue thickness can be estimated.
The choice of radiographic marker is important and should be based on two principles: it should be shown clearly on the radiographic image and should not interfere with the imaging modalities. 12 In the past 2 decades, many types of radiographic markers have been proposed for implant placement treatment planning. Presently, gutta percha, metal foil, or rod and barium sulphate are commonly used in implant radiographic imaging. 5,13-17
A new contrast medium, Lipiodol ultra-fluid (Laboratoire Guerbet, Paris, France), is iodized poppy-seed oil that has the appearance of a natural vegetable oil with a similar color and viscosity. It is radiopaque because of its high iodine content (38%). Lipiodol is medically used for lymphography and computerized tomography scan for hepatocellular carcinoma. 18 In dentistry, Lipiodol is injected into salivary gland for sialogram.
Lipiodol is chosen as a radiopaque medium in radiographic-surgical templates for dental implantology because of its several desirable properties. It is biocompatible with human tissues. It is organic and can be dissolved in another organic solvent such as monomer of acrylic resin (as like dissolves like in chemistry), and the amount of Lipiodol that is used can easily be quantified. Unlike barium sulphate, the radiopaque template is optically transparent (with a slight yellow tint), which facilitates the good visibility of surgical sites when it is modified to become the surgical guide for implant placement.
This article describes a simple method of fabricating an all-purpose template with the incorporation of Lipiodol into autopolymerizing acrylic resin, and a case is presented to illustrate its application. When used in conjunction with Scanora, the radiographic template depicts the contour of the future prosthesis, the angulation of the planned implant, and the thickness of the soft tissue.
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