Digital Impression Techniques in Implant Dentistry

Introduction:

Utilizing modern imaging technology, a digital impression is a three-dimensional model of a person's teeth and oral tissues. It replaces the traditional method, which entails manually imprinting the teeth with a material that resembles putty. Digital impressions are made using specialized scanners that use lasers or optical sensors to create an exact digital model of the patient's teeth. Among other dental applications, these digital impressions can be used to make crowns, bridges, orthodontic aligners, and other dental restorations. Higher patient comfort, speedier processing, increased accuracy, and the ability to store and transmit digital data electronically are some of its advantages.

What Is the Purpose of Digital Intraoral Impressions?

In the field of present-day implantology, the position of dental implants, either in partial or fully edentulous patients, can be optimized and ascertained to meet these patients' functional and esthetic concerns. Dental implantation is also superior in chewing efficiency and avoiding functional discrepancies that may occur due to bone volume affliction, as in the case of conventional bridges or removable dentures. Digital intraoral impressions aim to transfer the implant position correctly without any angular deviations. This ensures that no biological or prosthetic complications arise and that the final customized fit of the implant denture or implant prosthesis remains predictable, meets the patient's functional needs, and provides esthetic satisfaction.

Why Is Digital Impression Technique Beneficial?

The digital techniques for impressions in implant dentistry utilize intraoral scanners that use a laser or light beam (structured light) directed toward the object to be digitized. In implantology, the coordinates are needed for correct implant positioning. The potential of intraoral or digital impression systems in the market is promising over conventional impression techniques and allows rapid digital data transfer followed by fabrication of interim prosthesis. Digital impressions also avoid the hassle of delivering the impressions to the lab and pouring or scanning them. Additionally, digital impression techniques reduce the number of patient appointments at the dental clinic and may result in a shorter treatment span. This also holds when the patient needs to be scheduled for multiple appointments while planning, checking, and pre and post-implant prosthetic protocols for accuracy and correct fabrication.

What Are the Drawbacks of Digital Impressions?

Despite the benefits, the only drawback currently observed in digital impression techniques is that in largely edentulous patients, the impression may get distorted owing to the vertical plane discrepancies in these individuals. This results in a lack of support during the drilling procedure, where the surgical template for the implants may get tilted, which may lead to distortion in the vertical plane. The treatment of entirely or largely edentulous patients is challenging to the implantologist; hence, techniques used in digital scanning and intraoral digital impression protocols need to be further studied and improvised.

What Are the Exclusion Criteria for Digital Impression Techniques or Guided Implant Surgical Procedures?

Patients with certain debilitating conditions are contraindicated for implant treatment:

• Patients who are generally contraindicated for oral surgical procedures owing to systemic health issues.

• Invasive cancers.

• Irradiation of the head and neck.

• History of drug abuse.

• Alcohol abuse.

• Pregnant and nursing patients.

• Severe bruxism or clenching (parafunctional habits).

• Psychiatric disorders.

• Patients with poor oral hygiene or lack of oral hygiene awareness have poor motivation.

• Patients with an inability to complete dental follow-ups.

• Immunocompromised patients.

• Untreated or severe periodontitis cases.

• Patients with uncontrolled diabetes and hypertension.

What Is A Prosthetic Driven Workflow Plan?

In the digital impression techniques of implant dentistry, the patient's initial screening and evaluation are completed by preoperative photographs and radiographs for dental reference. These references are to be used after the completion of dental implantation for accurate prosthetic fit.

Panoramic radiography like OPG (orthopantomogram) and 3D imaging modalities like CBCT (cone beam computed tomography) also hold value for preliminary assessments of the area for dental implantation. CBCT, however, is mainly used in this protocol for prosthetic-driven plans and workflow to analyze or study the dental arches separately using wax bite.

• First, the implantologist takes a digital impression of the patient's dental arches. Then, the digital data is transferred in STL format, which is to be imported into 3D design software systems (examples such as DentalCAD, Exocad, etc.) for creating a virtual wax-up.

• This is a simpler procedure in comparison to the conventional in-clinic implant impression techniques, where an impression is taken manually by the dentist with a customized tray and polyether implant impression material (like impregum impression material), and then a dental wax-up is done.

• The processed data is in DICOM data format (both in the case of digital or conventional impression techniques) to generate the master cast.

• Digital impression processing also considers the location of the dental implant, the quality and quantity of bone, the thickness of soft tissue in that region, and the anatomic landmarks. This planning helps the dental surgeon visualize the shape and volume of the final restorative unit.

• When this prosthetic-driven workflow is approved by the implantologist, the stereolithic surgical guide template is fabricated.

• Following the placement of dental implants, oral hygiene, and maintenance instructions are given utmost importance, especially for creating patient awareness about the importance of oral hygiene in osseointegration of implant bone fusion.

• After three to six months of implant placement, customized open tray impressions are taken, and then cement or screw-retained restoration is delivered as an implant prosthesis.

• The occlusion of the patient is adjusted, and the patient is asked to follow up every six months.

Why are Digital Impressions Preferred?

For various reasons, dental practitioners favor digital impressions over traditional ones.

• Accuracy: The digital scanning method minimizes the possibility of faults or inaccuracies that can arise with traditional impressions by precisely capturing every detail.

• Comfort: Using a wand-like device to capture digital impressions eliminates the need for heavy, uncomfortable impression trays filled with putty-like material.

• Efficiency: The subjects spend less time in the chair because these impressions are taken swiftly. Since information is electronically kept, there is no need for destruction or transit.

• Visualization: Dentists can rotate, enlarge, and examine digital pictures from various perspectives. By providing patients with a visual representation of their dental condition and suggested course of treatment, this improved visualization facilitates more precise treatment planning and enhances patient education.

Conclusion

Hence, the surgical template guide produced by CAM-CAD (computer-aided designing or computer-assisted manufacturing technology) or a high-resolution 3D printer allows for proper stabilization and an accurate fit of the implant prosthesis in the patient's mouth. Moreover, the introduction and advancement of 3D imaging technologies in digital impression techniques have become popular over the last few years not only for the prosthetic success of dental implants but also for meeting the patients' esthetic or functional demands and expectations.