Surgical guides have been in use for years, and some clinicians experienced in placing dental implants still find that a simple surgical guide is sufficient to ensure a successful surgery. However, with the increasing popularity of CAD/CAM technologies, it is becoming more common to use CAD/CAM guided surgery, which utilizes surgical guides that have been manufactured to replicate a digital treatment plan. The need for accurate implant placement is well-known, particularly for achieving the correct angulation of implants in preparation for restoration. As this technology becomes more widely adopted, clinicians can more precisely plan surgery and prosthetic treatment phases, providing patients with better and more predictable treatment outcomes.
Planning Computer-Assisted Surgery with a Surgical Guide
The purpose of using a surgical guide is to accurately transfer the diagnostic and planning stages of treatment to the surgical stage. Because a surgical guide is a very exact transfer tool, a high degree of precision is important when planning surgery. The prosthetic design should consider the patient’s needs and desires and must provide good functionality. Optimal implant positions can then be determined according to the prosthetic design, accounting for any limitations related to bone density and locations of important structures in the bone. The surgical guide will transfer this design, allowing you to perform implant surgery with the utmost precision. The prosthetic design requires very specific information, regardless of the software or method used to create the surgical guide.
Key Diagnostic Information Required for CAD/CAM Surgical Guides
In addition to conventional digital X-rays, it is essential to have radiological data generated by a cone beam CT scan. Cone beam CT scans are best the imaging method for gaining the necessary information about an implant site. A standard digital x-ray is merely a 2-D image and there is the possibility that anatomic landmarks such as nerves and sinuses may be superimposed on one another. While it is possible to accurately assess the width of mesiodistal bone in a standard digital x-ray, it is only part of the information required for successful implant planning. In contrast, a 3-D image provides accurate information as to the location of nerves, the density of the bone, and the submandibular fossa. By utilizing this information, implants are digitally inserted so the optimal position can be determined. At the same time, provisional or final restorations can be planned and checked to ensure they will provide the desired outcome. Digitally planning the proposed location of the dental implants will allow you to create the proper separation between the implants and teeth.
More intraoral information can be provided by using conventional or digital impressions. Planning the implants’ positions creates further diagnostic information. All this information will be utilized by the appropriate software program to generate the data needed for manufacturing the surgical guide.
Designing and Manufacturing a Computer-Assisted Surgical Guide
Your surgical guide can be manufactured by your chosen dental laboratory, and, once you have transmitted your datasets, the guide can be designed and created to your specifications. This part of the treatment process is generally planned in close collaboration with your dental laboratory.
One thing you will need to consider when designing your surgical guide is how it will be supported. Some surgical guides are teeth-supported, while others will be supported by the mucosa. Bone-supported guides can also be used when it is necessary for the surgical guide to have direct contact with the bone. Bone and mucosa-supported guides are often used in conjunction with fixation pins inserted into the bone to help fully stabilize the surgical guide. It is thought that mucosa and teeth-supported guides offer the greatest stability. However, so many designs are available from numerous manufacturers that it is difficult to fully assess the comparative precision of each guide.
Manufacturing CAD/CAM Surgical Guides
Several different methods can be used when manufacturing a surgical guide. The first is called stereolithography, which consists of hardening layers of a liquid resin bath using a laser. Another similar method is called selective laser sintering, where, instead of a resin bath, a powder bed is used to make the guide. Milling technologies can be used to manufacture a surgical guide from a solid block of material. Conversely, 3D printing technologies are becoming more common. No matter which method you choose, all provide precise transfer of surgery data to the guide.
Benefits of Using CAD/CAM Surgical Guides
Patients can benefit from shorter and less invasive surgeries that enhanced precision provides. The knowledge that surgery has been meticulously planned can be tremendously reassuring for patients who feel a little anxious or nervous.
Using a surgical guide helps provide more predictability which from the patient’s point of view is very important. Many patients expect their clinician to know exactly how they feel about having missing teeth restored, and quite understandably will want to know exactly how they will look once treatment is completed. This is very difficult for anybody to predict without clearly visualizing the amount of bone and gingiva that has been lost and without pre-planning the implant restorations.
Some clinicians make a point of sitting down with patients who are to receive dental implants to discuss their CT scan. This allows the clinician to talk to patients about any biological limitations, for example, limited bone, and to show them in 3-D or by using a diagnostic wax-up, the predicted outcome of treatment including the final results. Using a surgical guide accurately replicates the treatment plan so you can be more confident when discussing proposed treatments with patients and it is a great way for patients to understand their dental health a little more easily. This can be especially useful if a bone graft could help improve the esthetic outcome of treatment, providing the patient with a visual reference showing exactly how this would affect the appearance of their implant-supported teeth.
CAD/CAM technologies can be used to fabricate immediate provisionals, which are created during the treatment planning process, and, on some occasions, the final restorations and abutments can be manufactured before implant surgery.
Using a surgical guide helps to accurately communicate the desired position of the dental implant to the clinician placing the implant. If you use a surgical guide, the implant can be inserted in the location that provides the best long-term peri-implant soft and hard tissue support and which facilitates the ideal emergence profile. The surgical guide can control the depth, mesio-distal, and buccal-lingual location of the implant, as well as the implant angulation.
Often clinicians will choose to use a surgical guide for safety, as the guide can rest on the bone, gingiva or teeth and has stops that limit the depth of the drill and which in turn limits the depth of the dental implant. With this approach, there is no need for guesswork.
Surgical drilling protocol and the dental implant placement can be performed with the guide in position. This means that, if appropriate, and if sufficient keratinized gingiva and bone are available, a flapless technique can be used. A flapless approach combines enormous precision with a minimally invasive surgery that doesn’t compromise on the outcome of the treatment. This technique can be performed more quickly and offers faster healing for patients. Flapless surgery may be more appealing to patients who are a little anxious about treatment.
Treatment planning can be optimized to provide maximum bone support in relation to anatomic structures, which may be particularly helpful when immediate extractions are required. Good treatment planning allows surgery to be performed in a very precise and controlled manner.
Using a surgical guide allows immediate CAD/CAM abutments and restorations to be designed and manufactured, giving clinicians greater control over the esthetic outcome of treatment. This, in turn, will help to provide your patients with highly customized and precise restorations.
Possible Limitations of Using CAD/CAM Surgical Guides
While there are significant benefits in choosing CAD/CAM surgical guides, there are limitations with any treatment. It is important to closely monitor treatment to help eliminate the potential for errors. One area where errors might occur is during the data gathering and planning phases. All the data collected should be carefully evaluated to ensure any possible errors are detected before planning the implant treatment. It is essential to precisely carry out the implant positioning and the planning phases for prosthetics. Generally, an implant specialist from the dental laboratory liaises closely with clinicians during the planning phase, and treatment is co-planned before the final plan is approved by the clinician. Despite the advantages of using advanced technology, proper planning and good clinical judgment are still of paramount importance to the success of implant treatment.
During the planning phase, other factors to consider include possible hardware limitations. The distribution, implant length, and orientation can be limited by the inter-arch space. Implant locations and minimal distances between implants can be affected by the thickness of the surgical guide and by the thickness of materials and sleeves on the guide. It is also important to think about the patient’s ability to open their mouth during surgery, as this can limit the length and positioning of the implants. Lastly, the surgical guide must be properly positioned in the mouth and its location and accuracy checked before surgery commences.
Computer-guided implant surgery and computer-assisted design can give clinicians a more efficient, precise, and minimally invasive way to treat patients. When properly planned, it can provide considerable benefits for clinicians and patients.
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