Articles - Forum Implantologicum

Article

Feature Article

Nov 13, 2019 // 10 min read

Current State of CAD/CAM Technology in Implant Dentistry

Dean Morton

Waldemar D. Polido

Wei-Shao Lin

DOI: 10.3290/iti.fi.45649

Abstract

Complete or partial digital workflow utilizing computer-aided design and computer-aided manufacturing (CAD/CAM) technology provides dental clinicians with ample options to treat their patients in a more effective way in daily practice. Dental clinicians and technicians need to recognize the limitations and proper indications of currently available technologies to accomplish optimal clinical care outcomes for patients. This article aims to narratively review various current CAD/CAM technologies (such as digital data collection, the development in CAD software programs and manufacturing platforms) in implant dentistry and discuss their advantages and limitations.

Introduction

A comprehensive digital workflow process for treatment including dental implants begins with data collection. Digital data collection may include 3-dimensional (3D) object scanning and obtaining a digital volume (CBCT). Together, the components of data collection allow for comprehensive treatment planning in which implant therapy is thought of as a singular entity and part of a total plan for the patient (Gallucci et al. 2019, Morton et al. 2019). Although the concept of comprehensive planning and treatment is embraced, this article will focus on those segments of the workflow traditionally considered to be of a restorative nature. Subsequent to data collection, the primary focus will therefore be computer-aided design and computer-aided manufacturing (CAD/CAM) of prostheses and associated processes.

Fig. 1: An intraoral scan can be used for the pre-operative diagnosis and treatment planning of static computer-aided implant surgery (s-CAIS)

Fig. 2: When combined with a scan body, an intraoral scan can record the position and the timing of dental implants for the subsequent prosthesis fabrication

Fig. 3: An intraoral scan is more hygienic when an impression is desired during surgery. It may be of clinical convenience and ease if a patient is undergoing orthodontic treatment and is fitted with orthodontic brackets

Fig. 4: The bevel near occlusal third on a scan body is a critical design for the CAD/CAM software to register the implant position and timing. The scan body should be positioned in a way that the bevel on the scan body facing area is easily accessible for intraoral scanning (generally speaking, towards the facial surface)

Fig. 5: The distance between implants (edentulous space) often affects the overall accuracy of intraoral scans greatly

Fig. 6: Scanning the edentulous patient can pose a clinical challenge to capturing an accurate soft tissue extension, the maxillomandibular relationship, and inter-implant relationships

Fig. 7: The intraoral scan was sent to the dental laboratory for the design and fabrication of a CAD/CAM interim PMMA hybrid prosthesis

Fig. 8: Occlusal view of CAD/CAM interim PMMA hybrid prosthesis

Fig. 9: The maxillary prosthesis was milled with a tooth-colored PMMA CAD/CAM block and layered with soft-tissue-colored laboratory composite resin

Fig. 10: When the registration of soft tissue’s dynamic/functional movement is indicated for an implant-retained prosthesis, a traditional analog impression can be made to obtain proper soft tissue extension

Fig. 11: A dental stone cast can be digitalized with a laboratory scanner for the subsequent CAD/CAM prosthesis fabrication

Fig. 12: Representation of scanned dental cast, and the design of CAD/CAM bar on 3 dental implants

Fig. 13: Computer validation of the design of CAD/CAM bar

Fig. 14: Different economic extraoral facial soft tissue surface scanners are now commercially available

Fig. 15: Ample lighting is desired while obtaining facial scans, and additional photography lighting equipment can be purchased to improve the overall quality of facial scans

Fig. 16: A 3D virtual patient can be obtained with the superimposition of extraoral facial and intraoral dental scans

Fig. 17: Using the facial anatomic landmarks, a virtual articulator may be used to simulate/estimate the patient’s dynamic occlusal contacts

Fig. 18: Although CBCT allows the 3D imaging of the craniofacial hard tissue, it only has a limited field of view and contrast resolution for facial soft tissue

Fig. 19: The craniofacial hard tissue reconstructed from CBCT volumetric data can be superimposed with digital photographs to create a 3D virtual patient with photorealistic appearance

Fig. 21: The approved diagnostic tooth arrangement can be used for prosthetically-driven s-CAIS planning

Fig. 22: CAD/CAM surgical templates for planned s-CAIS

Fig. 23: CAD/CAM interim prostheses for planned immediate provisionalization

Fig. 24: Example STL file representing a mandibular intraoral scan of 4 dental implant scan bodies

Fig. 25: Example STL file representing a surgical template and complete dental prosthesis for s-CAIS

Fig. 26: Example PLY file representing a post-operative intraoral scan

Fig. 27: Example proprietary file representing a mandibular intraoral scan of 4 dental implant scan bodies. The STL file in Fig. 24 was converted from this proprietary file format, and the surface texture and color cannot be preserved after conversion

Fig. 28: Milled PMMA can be used as a prototype prothesis testing the functional and esthetic outcomes prior to the fabrication of definitive zirconia prosthesis

Fig. 29: After 1 to 2 months of intraoral function, the prototype prostheses may demonstrate occlusal changes resulting from patient’s dynamic occlusion. The prototype prostheses can be sent back to the dental technician to be used as a reference when designing the definitive prostheses

Fig. 30: Design of definitive zirconia prostheses

Fig. 31: Milled definitive zirconia prostheses prior to coloring and sintering

Fig. 32: Milled definitive zirconia prostheses ready for delivery

Fig. 33: Intraoral view of seated milled maxillary and mandibular definitive zirconia prostheses

Fig. 34: Post-operative panoramic radiograph

Fig. 35: 3D printed interim implant crown with a desktop DLP printer

Fig. 36: 3D printed surgical template with a desktop SLA printer

Fig. 37: 3D printed interim denture with a desktop DLP printer. Although desktop SLA or DLP printers are convenient for in-office production, one major limitation is that only one material (in color or stiffness) can be used in a single print job. When different materials are desired (such as pink and white resin in this instance), two separate prints and post-printing assembly are needed

Fig. 38: Industrial 3D printer can operate different materials in the same print and produce objects with different colors, textures, gradients, transparencies and durometers in a single print operation. These dental casts were printed with a PolyJet printer (J750; Stratasys Ltd)

Fig. 39: Design of CAD/CAM bone reduction and surgical template for s-CAIS

$Fig. 40: The bone reduction and surgical template can be milled or printed from the cobalt-chromium (Co-Cr) or titanium alloy. Although the production cost with these materials could be higher, they offer superior mechanical strength and accuracy, which may in turn reduce the intra-operative complications, such as fracture of templates, insufficient mouth opening leading to insufficient operation access, and aggressive flap design needed to accommodate the bulky resin templates$

Fig. 41: A complete digital restorative workflow starts with an intraoral scan capturing implants’ position and timing with scan bodies

Fig. 42: Virtual titanium base abutments were placed onto the implants

Fig. 43: Virtual design of CAD/CAM monolithic zirconia implant crowns

Fig. 44: Milled zirconia crowns can be completed with surface finishing, polishing and characterization. Resin luting agent is used to lute the zirconia crowns and the titanium base abutments together prior to insertion

Fig. 45: When the dynamic soft tissue movement is critical for a removable implant-retained prosthesis, a traditional impression should be made for optimal clinical outcomes. An analog cast can be digitalized in the dental laboratory with a laboratory scanner

Fig. 46: Continuation of digital prosthesis design after analog cast digitalization

Fig. 47: Printed cobalt-chromium (Co-Cr) framework for removable dental prothesis

Fig. 48: Intraoral view of CAD/CAM implant-retained removable partial dental prosthesis

Fig. 49: When the clinician requires a clinical trial insertion, and/or the dental technician needs the articulated analog casts to re-position the manufactured framework or prosthesis for subsequent finishing process, a partial digital workflow should be used. This figure illustrates the digitalization of a milled cast, and diagnostic tooth arrangement after obtaining patient’s approval from clinical trial insertion

Fig. 50: Design for a CAD/CAM titanium framework on 5 dental implants

Fig. 51: Design of the CAD/CAM crowns fitting on the framework

Fig. 52: CAD/CAM (milled) anodized titanium framework and zirconia crowns

Fig. 53: Implant-supported complete fixed dental prosthesis (titanium framework and individual monolithic zirconia crowns)