Radiographic Splints for Dental Implant Planning
The radiographic splint is a fixture constructed from a diagnostic wax-up, i.e., on the study model, the prosthesis is modeled in wax or other material to restore teeth with ideal morphology and position that we aim to replicate in the patient’s mouth. This allows us to consider and decide, together with the radiological study, the number of implants that will be placed, their location, and the most suitable angulation.
The use of a radiographic splint is helpful for:
- Determining the number, angle, and location of implants.
- Providing a favorable distribution of implants over the arch, depending on bone availability.
- Avoiding an unfavorable discrepancy between the design of the restoration and the location and size of implants.
It is advisable to manufacture them from wax-ups of teeth, which serve as radiographic markers to indicate the planned implant locations.
Types of Radiographic Splints
Splints Constructed with Metal Ball Markers
Their role is to provide diagnostic information before surgery. These splints are constructed with metal balls located in the area of implant placement. It is difficult to precisely control the implant angle with this method. Moreover, these areas can help estimate magnification error and identify if the panoramic radiograph is distorted due to an asymmetric patient position, which can make fields appear oval. The size of the balls used in the radiography is compared. The magnification error, which can be 20-30% in the vertical dimension compared to the real bone height, should be taken into account when assessing bone availability in the severely resorbed mandible.
Splints Constructed with Gutta-Percha Markers
These splints are constructed of acrylic with gutta-percha cylinders embedded at the proposed implant site. This method is very useful because it does not produce distortion that alters the interpretation of measurements. For implant therapy, it is crucial to establish the number, length, diameter, and position of implants based on bone volume and capacity.
Splints Constructed with Barium Sulfate and Self-Curing Acrylic
This method involves duplicating the wax-up with a radiopaque material, usually a mixture of barium sulfate and self-curing acrylic. This type of guide is designed for CT scans. It helps obtain an anatomical representation of the restored teeth. For additional information, and to visualize the same tooth as shown in cross-sections in the CT scan, a 2 mm diameter drill hole can be made at the point on the occlusal surface where the implant access port is planned.
The marker, associated with bone anatomy and the planned restoration, can even provide an idea of the angulation difference between the clinical crown and the implant, helping determine if an angled abutment should be used.
Bone Assessment Techniques and CT Scan Advantages
The most useful techniques for studying available bone are:
- Orthopantomography
- Computed Tomography (CT)
- Magnetic Resonance Imaging (MRI)
- Conventional Tomography
To interpret CT findings, it is necessary to use a radiographic splint constructed from radiopaque material that represents the correct position of the future prosthesis. This allows for accurate assessment of the position and angulation of future implants. With CT, we have the possibility of sectional and three-dimensional reconstructions of the maxilla and mandible, fulfilling the implantologist’s desire to know with absolute precision the dimensions and exact densitometry of the implant area. Software such as Dentascan facilitates this.
The advantages of a computed tomography study using Dentascan include:
- Dimensional sectional study of the jaws.
- Minimal distortion and virtually absent magnification.
- Accurate measurements of height and width of key anatomical structures, which allows us to assess bone density.
Finally, we emphasize that improper planning in implant rehabilitation treatment is a common cause of late failures.