Optimize Workflow Efficiency by Integrating Dental Imaging Technologies

In modern dentistry, the integration of computer-aided design/computer-aided manufacturing (CAD/CAM) technologies has revolutionized the way dental professionals diagnose, plan, and execute treatment in implant dentistry. Implant surgeons often use CAD/CAM technology to improve accuracy in the final implant position.¹ These technologies have significantly impacted the surgical and restorative workflow and improved efficiency by the integrating of dental imaging technologies.^2,3 To understand how dental imaging technologies can be integrated effectively, obtaining a strong knowledge base on the various imaging modalities commonly used in implant dentistry is critical.

Intraoral surface scanning has revolutionized the dental industry. Historically, intraoral surface images were obtained by a lab scanner of a conventional impression. Today, intraoral scanners are used directly in the mouth (with some limitations) for capturing direct digital impressions.⁴ Intraoral scanners allow the capture of digital impressions of the dental arches using only a light beam, without the need for individual trays and materials (alginate, silicone, polyether) that were traditionally used to take impressions.⁵

Digital implant planning with the superimposition of intraoral surface scanning on cone-beam computed tomography (CBCT) images has been successfully incorporated by most current implant planning software. The data merging allows the integrated visualization of patient’s alveolar bone and adjacent structures along with intraoral surface anatomy, including teeth and soft tissue.

The intraoral surface imaging also enables the use of a digital set-up of the dentition for partially or fully edentulous arches. This is accomplished using CAD software or the implant planning software for a prosthetically driven implant position. This technology is applied for static computer-assisted implant surgery using a CAD/CAM-generated surgical guide. The outcome of this assures a restoratively planned implant position, thereby achieving more predictable outcomes and increased efficiency.⁶ These three-dimensional (3D) printed surgical guides are a fundamental part of this workflow to transfer the digitally planned implant location into the patient’s mouth.⁷

Another advanced in digital technology is the use of dynamic camera navigation and robotic surgical guidance for implant placement.⁸ Robotic guidance brought the term “haptic” into the surgical vocabulary. Haptic refers to physical guidance in addition to visual and auditory guidance during implant surgery; the robotic system’s software program uses a CBCT scan of the patient and allows the 3D planning of ideal implant positioning based on bone availability, biomechanical load, and the design of the definitive prostheses. The robotic assistance then provides the surgeon with physical guidance of the drills to the desired position, angulation, and depth. When the orientation is accurate to the plan, there is no robotic (haptic) resistance; if the drills deviate, the robot will constrain the tool axis to the planned orientation. Haptic refers to the surgeon experiencing a vibrating resistance to the normal sensations of drilling or implanting.⁹

While surgical principles are widely accepted in scientific literature and adopted by surgeons worldwide,¹⁰ significant advancements in rehabilitative protocols, such as the introduction of novel materials and the digitization of clinical and laboratory processes, have been made. The process of immediate fixed implant rehabilitation for complete edentulous patients is a high-risk, challenging undertaking because it compresses surgical, prosthetic, and laboratory procedures into a very short time, stressing all disciplines and procedures. Additionally, all steps must be executed well, or the implants or prosthesis will fail.

One of the hurdles lies in the ability to precisely capture full-arch implant rehabilitations when multiunit abutments (MUAs) are employed.¹¹ This challenge primarily arises due to accuracy limitations observed in both intraoral scanners and traditional methods.¹² The success of the treatment hinges on the ability to faithfully transfer the implant position information.

To enhance the workflow and guarantee a passive fit, photogrammetry improves success in these rehabilitation scenarios.¹³ As pioneers in providing immediately loaded full-arch implant restorations, we trademarked the term “Teethtoday™“ in 2002. Since then, we have incorporated digital dental technology into almost all our implant treatment, specifically for complete-arch, immediately loaded implant treatment. Currently, several digital workflows are available for full-arch planning and rehabilitation. Our goal is to obtain a predictable, reproducible, and efficient complete digital workflow.

Photogrammetry

Photogrammetry is a technique that collects data and information on the shape and location of and object relative to that of others in a given space and on its movement, or deformation.¹⁴ A recently introduced photogrammetric system for digital implant impressions, when using multi-unit abutments, could increase patient convenience while affording suitable accuracy. It is an alternative imaging method for multiple implant-supported restorations including complete arch implant-supported fixed dental prosthesis. In photogrammetry, scans are recorded by an extraoral receiver, eliminating the need for making overlapping images with intraoral scanners and, theoretically, positioning the 3D implants more accurately than intraoral scanners.¹⁵

This method has reported the lowest margin of error and deviation. Studies have shown as little as 5 to 5.6 µm or as low as 4 µm in favorable conditions.¹⁴ Given that traditional methods for capturing implant data in full-arch restorations were either not accurate or required significant labor and time, the adoption of dental photogrammetry systems is the essential component in facilitating reliable and efficient fully digital full-arch restorations with guaranteed passive fit.¹⁵

Clinical Report

This clinical report demonstrates a full-arch workflow that integrates photogrammetry with intraoral scanning to deliver a same-day milled interim prosthesis and later a milled definitive zirconia full-arch prosthesis (Figures 1 to 10). Specialized scan bodies are positioned on the implant multi-unit abutments (Figure 1), and an extraoral scanner is employed to meticulously record data on the precise location and angulation of the abutments (Figure 2).

To illustrate the technique, a complete treatment sequence of a patient with terminal maxillary and mandibular dentition is presented (Figure 3). A preoperative CBCT scan is captured for diagnosis and digital implant planning. The first phase involves generating a comprehensive digital impression of the entire mouth using intraoral scanning and photographs to create a digital smile design (Figures 4 and 5). This digital impression enables the creation of a prototype complete maxillary denture through a CAD/CAM software.

During the surgical procedure, all remaining maxillary teeth were extracted, and four to six dental implants are positioned in selected sites to maximize implant primary stability and prosthetic support. All implants ideally should achieve > 35 Ncm insertion torque or Osstell ISQ > 65. MUAs were placed. The implants were then immediately loaded on the MUAs.

After the surgical procedure is concluded, intraoral scan bodies were attached to the MUAs (Figures 6A and B), and a soft tissue scan was performed using an intraoral scanner (Figures 7 and 8).

The photogrammetry system generated a PIC file that contained the interrelated implant positions and angulations. It is exported in the open STL format that can be used directly in design software for superimposition (Figures 7 and 8). The second component was intraoral scanning of the soft tissues, which was imported into the CAD software, along with the PIC file, to complete the digital model of the patient (Figure 8).

The design stage of the temporary full-arch prosthesis after immediate implant surgery was continued in the CAD software. This design included the use of titanium bases made for multi-units (Figures 9A and B). A full-arch implant prosthesis was then fabricated with a milled prefabricated polymethylmethacrylate (PMMA) discs finished in a few hours and delivered for insert the same day (Figures 10A and B).

Digital Full-Arch Restorative Solution

The digital full-arch restorative solution system allows clinicians to capture implant positions accurately using only an intraoral scanner and scan gauges. Each scan gauge is individually accurately measured and registered to the user (Figure 11). The gauge set serial number is entered when the scan is uploaded. This information allows the pre-determined dimensions of each gauge specifically used for each user to correct the distortion correction coming from intraoral scanning in the data acquisition.

The intraoral scan is done twice and the scans are compared to each other for verification. If the scans are within preset tolerances, then they are deemed to be identical and accurate, which accomplishes a digital verification. If the intraoral scans do not pass, the dentist is immediately notified in the verification software that the scan was not accurate and should be repeated. For this reason, this workflow is considered accurate with most intraoral scanning systems. A tissue scan is also taken to merge with implant positions in order to create the full digital model.

A CBCT scan is captured for digital implant planning, a digital impression of the entire oral cavity is captured with an intraoral scan and photographs to craft a digital smile design (Figures 12). The scan data is uploaded. A virtual model is built, and framework design is performed (Figures 13A and B). The design is sent with a 3D model to review and request changes. After approval, an interim full-arch fixed prosthesis is fabricated in PMMA material (Figure 14).

Three months later, the interim prosthesis is removed, and scan gauges are attached to the MUAs (Figure 15). An intraoral scan of the edentulous maxilla is conducted using the IOS. The interim prosthesis in situ, the opposing dentition, and occlusal records are also digitized. A milled solid titanium frame with zirconia or acrylic overlay is fabricated (Figure 16). Tolerances of 10 microns are claimed for the fit of this system.

Conclusions

The current technology in implant dentistry has significantly improved the workflow for full-arch rehabilitations. The outlined digital workflows allows the delivery of an immediate complete-arch implant-supported fixed interim and definitive prosthesis for edentulous (or soon-to-be) patients in a more accurate and efficient manner. This benefits patients with a less invasive, more efficient procedure that may result in superior outcomes.

 (Note to Kim : References weren’t in the RTF file or in the pdf!)

From Decisions in Dentistry. August/September 2024; 10(5):36;39-41