Key words: Surgical guide; Oral implantology; Guided implant surgery

INTRODUCTION

The success of implant therapy depends on accurate implant positioning for optimal functional and esthetic outcomes. The Glossary of Prosthodontic Terms, Ninth Edition (GPT 9) defines a surgical template as a guide that assists in the proper placement and angulation of dental implants. Traditionally, these guides were cast-based and used wax-ups to replicate the prosthetic plan intraoperatively. With advancements in CBCT, CAD/CAM, and 3D printing, surgical templates have evolved into precise, digitally fabricated tools that accurately transfer virtual plans to clinical reality. Dynamic navigation systems now enable real-time drill tracking, enhancing accuracy, safety, and customization, making surgical templates essential to prosthetically driven implantology.¹

TYPES OF SURGICAL GUIDES

Based on the area of operation -
Guides for partially edentulous sites: Tooth supported or bone-supporteddepending on the amount of the edentulous space Guides for completely edentulous sites: Mucosa or bone supported.

Based on the support the surgical guides derive -
Tooth supported, Bone supported, and Mucosa supported.

Based on the accessibility -
Surgical guides can be open sleeve or closed sleeve (increased accessibility)

Base on utility -
Pilot guides, Complete drill guides and Safe guides/easy guides

Based on material -
Self/light cure acrylic resin, metal reinforced acrylic templates; vacuum formed polymers, milling, CADCAM prosthesis, stereolithographic models.²

Based on the amount of surgical restriction offered by the surgical guide templates -
Non-limiting design, Partially limiting design, and Completely limiting design

FABRICATION OF SURGICAL GUIDE

Creating a surgical guide is a complex process that requires attention to detail and a deep understanding of dental anatomy and surgical techniques. It involves a combination of manual steps and standard dental laboratory techniques. The guide is custom-made using various materials based on the patient’s needs and the specific procedure.

To ensure precision in implant placement, surgical guides are fabricated using a multistage process. The process involves using irreversible hydrocolloid to duplicate the diagnostic wax-up and creating two stone casts. A vacuum-formed template is then created on one of the casts, and teeth are cut off from the other cast to make way for the implants. The template is placed on the cast with teeth removed, and holes are cut through the template over the site of each implant. The optimal path of insertion is determined for placement, and holes are drilled in the cast where each implant will be placed. Brass tubes are attached to the template, and additional clear orthodontic resin is added to ensure proper attachment of the template. Finally, the guide stent is sterilized for the appropriate amount of time before surgery to ensure its safety and effectiveness.⁴

CLINICAL PROTOCOL FOR SURGICAL GUIDE UTILIZATION

The utilization of surgical guides in dental implant surgery involves a specific clinical protocol to ensure precision, accuracy, and optimal outcomes. This is a general clinical protocol for the use of surgical guides

Step 1: Diagnosis and treatment planning.

Step 2: Virtual implant and prosthesis planning with software.

Step 3: Selection of a particular implant system and components.

Step 4: Planning for the surgical guide compatible with a particular implant system.

Step 4a: If more than 3 teeth-tooth borne, if less than 3 teeth-mucosa or bone borne surgical guide.

Step 4b: Selection of anchors (depending on the site, implant number, angulation, and anatomical limitation)

Step 5: Surgical guide fabrication (online ordering is possible with most software)

Step 6: Disinfection of received surgical guides followed by evaluation of guides. Step 6a: For teeth supported-evaluate on cast and patients mouth.

Step 6b: For mucosa supported-evaluate on cast and patients mouth, for a mucosa-supported guide, it is recommended to make a surgical index to stabilize the guide during fixation. Step 6c: For bone supported-evaluate on digital bone model.

Step 7: Verification of specific surgical drills and drill keys.

Step 8: Stabilization of guides in patient’s mouth using anchor pins followed by verification of the guide stability.

Step 9: Drill sequence.

Step 10: Fixture installation (possible with safe guides)2

RECENT ADVANCES IN SURGICAL GUIDES

Digital planning and guided surgery
Guided implant surgery can generally be classified as dynamic or static - Dynamic guided surgeries involve the use of a computer-aided navigation system to allow for real-time implant surgery. The major advantage to the dynamic design is the ability to intraoperatively adjust the planned implant positioning whereas the static guided surgery approach is based on the 3-dimensional (3D) data obtained from cone-beam computed tomography (CBCT) and optical surface scanning, and computer-aided design/computer-aided manufacturing (CAD/ CAM) technology for virtual implant planning and guide fabrication. The fabricated surgical guide can be supported by tooth, mucosa, or bone. Additional stabilization and support can be achieved using mini-implants, screws, or pins. Once the guide is fully seated, the planed drilling protocol beings. The drilling protocol can include using the guide for the pilot drill only, or a partially or fully guided drilling protocol. The implant insertion can be executed without the surgical guide or through the guide via a fully guided approach.⁵


3D Printing Technology:
The use of 3D-printing technology to create surgical guides in dental implantology is becoming increasingly popular. The most commonly used technologies for this purpose are stereolithography (SLA), Digital Light Processing (DLP), inkjet, PolyJet®, Selective Laser Sintering (SLS), 3-Dimensional Printing (3DP), and Fused Deposition Modeling (FDM). While a variety of materials can be used, most dental applications use plastics, resin or plastic-based materials. SLA is a process that polymerizes monomer resin with a laser beam layer-by-layer until the printed part is completed. DLP is similar to SLA but uses a digital micromirror device (DMD) to project a mask of light that cures a layer in a few seconds. PolyJet® printing uses a UV lamp to cure material droplets onto the building platform layer by layer. SLS technology uses a high-power laser beam to sinter powder particles without melting. In FDM, a filament of material is melted and extruded layer-by-layer on a receiving platform.

The accuracy of surgical guides is dependent on the 3D-printing method used. While SLA has been the most commonly used method until recently, the advantages of other technologies, such as DLP and PolyJet®, are becoming increasingly apparent. These technologies offer good print resolution, the ability to print a wide range of materials simultaneously, and color parts. However, resin-based materials can become unstable over time, which is a common problem with all resin-based technologies. The benefits of using 3D-printed surgical guides include increased accuracy, reduced cost, reduced surgical time, and customization to patient geometry for better patient and surgeon outcomes.⁶


Dynamic Navigation Systems:
Image guided surgery, also known as surgical navigation guidance, has opened up new possibilities for implant treatment planning and placement in the medical field. Recently, this technology has also been introduced to implant dentistry by companies such as IGI in Israel and RobotDent in France. To use this technology, a CT scan is required to create a 3-D model of the patient’s jaw. Then, a specialized acrylic splint is created to match the patient’s jaw position. During implant surgery, the patient must wear this splint, which is equipped with strategically positioned infrared emitters. These emitters allow camera detectors in the room to track the movement of the patient’s jaw and the dental handpiece. This real-time tracking provides the surgeon with continuous feedback on the osteotomy location and its relationship to the desired implant location.⁷


Pros and cons of Dynamic Navigation Systems:
Dynamic navigation has advantages over static guided surgery, such as reducing costs and time needed for impression and laboratory procedures. It also provides a direct view of the surgical field and the use of standard drills, making it optimal for mouth opening reduction. Additionally, dynamic navigation allows for changes in implant planning to be made at the time of surgery, providing flexibility.

However, a disadvantage of dynamic guided systems is the need to pay attention to both the patient and the navigation system display simultaneously. This could be challenging when the tracking device is in the same location as the display. Systems that use a mobile screen fixed near the patient’s head on the dental chair may address this issue as they limit the movement of the surgeon’s head and their loss of sight of the surgical site.


Augmented Reality (AR) and Virtual Reality (VR):
AR and VR technologies have started to be integrated into dental implant surgery planning. These technologies can provide surgeons with immersive visualizations and interactive planning tools.

Virtual reality is the science of creating a virtual environment for the assessment of various anatomical regions of the body for the diagnosis, planning and surgical training. Augmented reality is the superimposition of a 3D real environment specific to individual patient onto the surgical filed using semi-transparent glasses to augment the virtual scene.⁸

In the two kinds of reality, AR is the first application began to widely use. AR, in which 3D virtual objects are integrated into a 3D real environment in real time. AR is to “virtualize” the virtual image into the real space, creating a completely virtual space around the user’s eyes to replace the real space. To make the users see a world which have a real environment and generated by the computer graphics over a real scene. And the VR offered the users a real, inside virtual 3D model. According to the display, to build a three-dimensional, seemingly true virtual world in the user’s eyes.⁹


Robotics in Dental Surgery:
Integration of robotic systems to assist or automate certain aspects of dental implant surgery, potentially increasing precision and reducing the margin of error.

To minimize the error associated with the surgical guide template, research has focused on assessing the technical precision of robot assisted static guided manufacture. Chiarelli and colleagues evaluated the accuracy of surgical templates based on image data with a noninvasive radiological stent transfer. When performing a surgical procedure by robot, the precision achieved was suitable for clinical needs (0.283 mm average position error and 1.798 average orientation error), which is better than stents based on stereolithography. Robot assisted manufacture of surgical templates can fully guide implant trajectory, be less expensive, and be minimally invasive. In addition, with less accurate tissue-supported surgical guides commonly in use, there is a great need for human error to be curtailed in clinical practice.¹⁰

Robotics integration in dental implant surgery is an emerging field that combines 3D printing, augmented reality, and virtual reality to enhance treatment planning and execution. The world’s first autonomous dental implant robot was developed by Beijing University and the Fourth Military Medical University Hospital in 2017, which can place implants accurately by merging postoperative cone beam CT with the desired preoperative trajectory. A surgical automatic robotic system was also evaluated for the accurate placement of long implants, such as zygomatic implants, in the edentulous maxilla.¹¹


DISCUSSION
Surgical guides are designed based on detailed 3D images of the patient’s oral anatomy. This allows for precise planning and placement of implants in the optimal position, depth, and angulation. In their study, Wang et al. showed that the use of the surgical guide makes a significant difference between the planned and actual positions of the implant, especially at the implant shoulder, root apex, and angulation relative to the manual implantation method¹². It has been clearly proven that the placement of dental implants using surgical guides is more accurate than implants that are placed without a guide¹³. In a prospective cohort study, the clinical performance of guided implant surgery was evaluated in comparison with the free hand method, and it was reported that implants performed using the surgical guide method increase the accuracy of implant placement. Also, angular deviation was one of the most important parameters improved using this method compared to the free-hand method.¹⁴

The use of surgical guides helps minimize trauma to surrounding tissues, nerves, and blood vessels. This precision reduces the risk of damage to adjacent structures during the implant placement procedure. Preoperative planning using surgical guides can ensure the safety of implant placement and reduce the incidence of complications, which is an important advantage for young and inexperienced surgeons and makes implant surgery easier for them. Also, when planning for a surgical guide, it is easy to evaluate that the proper angulation and occlusal relationships are more readily assessable using dental casts where the lingual aspect is not obscured. In another study, which was performed comparatively between two groups of patients, it was observed that, in flapless patients, the duration of surgery, pain intensity, and analgesia, and cases of trismus and bleeding, were much lower than in patients with free-hand surgery implants¹⁵. One of the most serious complications of implant surgery that can be minimized with guided implant surgery is damage to important anatomical structures (sinuses, nerves, arteries, and teeth). It also provides the dentist with increased vision of the surgical site and easy access to flap exposure.¹⁶

Surgical guides enhance predictability, efficiency, and patient comfort in implant placement. They allow for tailored approaches to complex cases and facilitate communication between the dentist, surgeon, and dental laboratory. Though the initial cost is an investment, surgical guides can lead to cost savings in the long run due to increased precision and reduced complications.

Dental implant surgical guides have advantages in accuracy and efficiency but have some possible drawbacks to consider, including increased cost, limited flexibility, technical challenges, overreliance on technology, patient-specific factors, and a learning curve for practitioners.

Conclusion

Advancements in radiographic techniques and computer software programs have revolutionized the planning process for complex implant cases. Although the field of dentistry is continuously evolving, it is important to exercise caution in understanding the differences and limitations of these innovations. Artificial intelligence have evolved recently and started to play an important role in every aspect of implant planning. Further research is necessary to determine whether these new approaches will enhance surgical outcomes and long-term prosthetic success, but they hold great potential for further advancements in the field.

References