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- Surgical: the hole must be positioned in sufficient bone to hold the implant
- Prosthetic: the hole must be correctly aligned with the position of the future tooth to restore it correctly
To meet these challenges, doctors can obtain 3D data of a patient’s jawbone (typically through a CT scan), import the data into implant planning software, and virtually place the implant in the correct position. The CT scan-based surgical plan is then used to make a surgical guide for that specific patient/case.
Literature has shown that CBCT-based implant planning and surgical guides offer advantages to the surgeon, restorative dentist, and patient. Implants are placed where planned, in the ideal location, leading to improved surgical confidence, outcomes, and esthetic results. And many doctors have adopted guided surgery for all of their cases.
Benefits of CT-based guided surgery include, but are not limited to:
- Restorative-driven surgery: Implant placement is pre-operatively agreed to by the surgeon and restorative dentist
- Accurate placement: Implants are placed where planned, in the ideal location, leading to improved surgical outcomes and esthetic results
- Lower liability: costly surgical mistakes (i.e., perforating the side of the jawbone or sinus, or damaging the mandibular nerve) are minimized because patient anatomy is known
- Sub-gingival knowledge and planned placement provide a better, more predictable, surgical experience
- Enter surgery with less stress and more confidence, knowing fewer anatomical “surprises” await
- More trust in a flapless protocol, which provides a more painless patient experience and recovery
- Spend less time in surgery
- Minimize intraoperative radiography (“check films”)
However, guided surgery still requires experience and good judgment. No matter how confident a doctor is in their treatment plan, they must still assess the placement of the surgical guide and implant in vivo.
Research has shown that 3-D treatment planning provides the clinician with a greater depth of information than traditional models, and that CT-based surgical guides are more accurate than free hand drilling as well as more accurate than conventional surgical guides.
Correct virtual planning delivers a restorative-driven placement that also meets surgical parameters. Everything once done on the bench – wax-ups, stents, barium sulfate (BaSO4) teeth – is now done virtually in the software, saving significant time. With a precise model of the patient’s jaw and the surgical guide, an accurate prosthesis can often be manufactured by a dental technician prior to implant surgery.
Surgical surprises, if present, can be reduced or eliminated. The amount and location of available bone can be determined in advance of surgery. Three-dimensional CT scans can provide accurate information on treatment area proximity to the aveolar nerve channel and sinus walls that 2-D x-rays may not always reveal.
For these reasons, there are many single tooth implant cases for which a surgical guide can assure a predictable result. For example, lower 2nd molar sites are often difficult to access both physically and visually, and can be further challenging if located posterior and deep in the patient’s mouth.
We place implants by computer-guided surgery.
To accurately place an implant, a precisely positioned hole has to be drilled into the jaw. Jaws come in different sizes, shapes, and angulations, and there are nerves, blood vessels and sinuses that limit where one can drill. Therefore, we use a 3D scan of your jaw to visualize your anatomy on the computer. Using special implant planning software, an implant can be placed virtually in the image of your jaw, while viewing the dimensions and shape of your jaw – and the locations of vital structures. These enhanced diagnostic tools help to reveal any potential problems and eliminate unexpected complications.
On the basis of this virtual plan, a drilling jig called a surgical guide is fabricated. The guide fits on your teeth and includes a guide hole, which guides the implant drill in surgery. In this way, the surgical guide transfers the virtual position of the implant to your mouth, and provides a method to precisely position the hole for the implant.
Our patented manufacturing process is designed to alleviate the warping and fit issues. ThinLayer® Guides are thin, which makes them much easier to use and conform well to teeth and gingiva, but also strong for handling and intended use. They fit snugly and you can see and access the drill site, approach the posterior with no additional vertical space, and modify the plan in surgery, if needed.
- Flared healing abutments: these abutments hang up on adjacent bone if any portion of the implant perimeter is below the osseous crest. Flap exposure is needed for access to remove interfering bone
- Preservation of attached gingiva: if the width of the attached gingiva is minimal relative to the implant diameter, an incision along the midpoint of the band of attached gingiva with flap reflection allows the attached gingiva to be mobilized along the buccal and lingual of aspects of the healing abutment. In contrast, the buccal and/or lingual attached gingiva would have been completely removed with a tissue punch
- Buried implant: if the implant must be buried for any reason, a flap must be reflected
- Ridge reduction
- Thin or knife edge ridge: although properly used surgical stents guide the drill to within 0.5 mm of the planned position, a thin or knife edge ridge should be exposed and visualized before an osteotomy is initiated
We have heard from many dentists that fit is an issue with many printed or milled guides currently on the market. And in the March/April issue of the International Journal of Oral and Maxillofacial Implants there is a study that compares the accuracy of computer-generated and conventional surgical guides. The authors concluded that “CAD/CAM more accurately reproduced planned implant positions”, however, they also mentioned that at least 20% of the “CAD/CAM guides need to be relined with clear acrylic resin prior to surgery to ensure stability.” They were “adjusted intraorally to achieve a stable fit prior to surgery.”
Farley et al, Split-Mouth Comparison of the Accuracy of Computer-Generated and Conventional Surgical Guides. Int J Oral Maxillofac Implants 2013;28:563-572.
- FOV: 8.5 cm (W) x 4-5 cm (H) for single arch
- Voxel: 0.4 mm
- Scan time: 4.8 sec
Stone model scan:
- FOV: 8.5 cm (W) x 4-5 cm (H) for single arch
- Voxel: 0.2 mm
- Scan time: 12.8 sec
Further guiding principles can be found in the EADMFR Basic Principles on the use of Cone Beam CT.
Please ensure that each model meets the following requirements:
- No voids
- Captures all anatomy
- Can’t have been fractured and glued back together
- Name of patient and doctor written on the back
- Alignment marks on models which are to be hand articulated
Steps to an accurate impression and model:
- Place alginate onto a finger and smear the impression material onto the occlusal surfaces of the teeth and into undercuts before the impression tray is placed to capture all anatomy
- Avoid bubbles when pouring the model:
- Pour alginate impressions immediately
- Apply a debubblizer (soapy water) to the alginate before the model is poured. Blow the debubblizer out with a gentle air stream before pouring
- When pouring the model, fill each concavity in the alginate individually, allowing the stone to flow sequentially from one concavity to the next
Be sure to create an adequate base on the models to prevent breakage in shipping. Thin models tend to break, even when padded.
For more detailed instructions, click here.
Please visit our protocols page for more details on how it works.