Paradigm Shift: Digital Processing Altering Denture Fabrication
David Avery, CDT, TE; Larry R. Holt, DDS; and David Little, DDS
Will digital methods soon overtake analog production of dentures?
Complete denture therapy has traditionally been viewed with much disdain by clinicians and technicians alike. Seen as less profitable than other types of restorative dentistry due to extensive chairtime versus production and inconsistent results, the clinical community has largely avoided this treatment.
Typically, removable prosthetics are a last option to be developed because the available sales opportunity is perceived to be lower than that of fixed restorations. Actually, current demographics show the potential for complete denture therapy to be huge due to the combined factors of the Baby Boomer generation living longer and increasingly fewer clinicians being prepared to treat them, with even fewer technicians available to support their clinical efforts. Finally, complete denture design software programs are now a focal point of the leading development companies.
There seems to be a prevailing notion that digital technology can eliminate the need for good sound technique. While all digital tools assist in the improvement of the end-result regarding consistency, the analogue clinical techniques of capturing complete records of soft tissue, occlusal registrations, and maxillary anterior tooth position are still basic requirements for the digital processes to succeed. This is the sometimes steep learning curve for the clinician newly attracted to denture treatment by digital possibilities.
The current commercial offerings show tremendous promise, with completed restorations offering improved fit and denture-base integrity. This author’s personal experience with the AvaDent® (AvaDent Digital Dental Solutions, www.avadent.com) and Pala® (Heraeus Kulzer, www.heraeus-kulzer-us.com) digital denture systems has been favorable. The constant challenge is the occlusal registration, particularly accurate vertical dimension of occlusion (VDO).
As a professional dental technician, I am greatly encouraged by the potential this digital direction shows. As always, new technology requires clinical education and technical support, a role that can and should be shared by the manufacturer and participating dental laboratory.
With dental practitioners increasingly learning the value of computer-aided design/computer-aided manufacture (CAD/CAM), and chairside scanners and digital laboratory technology becoming a significant part of daily workflow, denture fabrication is now benefiting from digital processes. The so-called “digital denture” is now a reality.
Denture fabrication can be a challenging task. Patients present clinically with variable anatomical features and functional limitations, and they often have unrealistic expectations and can be difficult to please. The classic clinical protocol can be time-consuming and difficult to master. Until recently there have been few advances for managing these cases; however, the advent of digital dentures provides a streamlined clinical protocol.
This new process begins with impression trays that are capable of accomplishing excellent capture of soft-tissue contours. All available digital denture systems have some variation of a well-engineered tray. Once satisfactory impressions are taken, centric relation bite records are accomplished using a central bearing device. Capturing centric relation has often confounded many practitioners, but this central bearing device ensures capture.
Once impressions and bite registration are captured, clinical data is transferred to a CAD processing center where all records are virtualized. The CAD program has a sophisticated algorithm that uses anthropometric averages along with clinical data to design a proposal for the definitive prostheses. This proposal is 3-dimensionally (3-D) printed and returned to the dentist for a highly precise try-in appointment. No longer do clinicians have to explain to patients why the try-in doesn’t fit well. In fact, CAM procedures practically eliminate the ever-present challenge of polymerization shrinkage that plagues classic denture fabrication. The patient enjoys the entire benefit of the accurate impressions that were originally taken, a benefit that is appreciated at both try-in and delivery appointments. It is typical for both upper and lower appliances to seat with a satisfying sound of developing suction; and, furthermore, few, if any, tissue impingements and sore spots can be anticipated. This alone makes the digital denture a success. Combine this with precise occlusion and the concept is made complete.
In this author’s experience with digital dentures, key benefits are simplified record-taking, fewer clinical visits, stable and predictable try-ins, and unemotional delivery appointments. Postoperative visits are typically uneventful and actually a pleasure to perform.
Despite the obvious need and growing demand for full-arch dental prosthetics, traditional processes involved with creating dentures are laborious and problematic for both dentists and their patients. Multiple appointments require preliminary impression-taking, waiting for laboratories to return a custom tray, taking final impressions, and working through base plate and wax rim try-ins, among other steps.
Conversely, with digital denture processes—whether CAD/CAM or 3-D printing—it is possible to treatment plan, try-in, and deliver final dentures in as few as 2 or 3 appointments. Currently, there are several digital denture providers and manufacturers (eg, Pala®, Heraeus Kulzer; AvaDent®, AvaDent Digital Dental Solutions; DENTCA™ CAD/CAM Denture, DENTCA, www.dentca.com; 3Shape, www.3Shape.com) that use similar methods for recording and digitizing impressions. However, they differ in terms of final denture fabrication (ie, milling versus printing).
With digital dentures, all of the information needed for designing the denture is captured in one dental office visit and stored in digital format. A virtual wax-up can be performed by first setting and moving the denture teeth on a computer; after this, a digitally produced prototype can be created for try-in. Instead of using wax rims and plates that typically don’t sit well, digital try-ins are a better representation of how final dentures will look, fit, and function. This makes the try-in appointment much easier, less time-consuming, and more accurate.
Additionally, there is usually no need for dentists to invest in any 3-D or CAD/CAM hardware or software, and the process involves significantly fewer steps than traditional denture procedures but with greater accuracy. As a result, because the procedures are not as labor-intensive as analog processes, digital dentures can be a cost-effective and efficient solution for edentulous patients. Moreover, digital denture data can be retained for future use, making it easy to fabricate a spare or replacement denture, or modify a previous denture if adjustments become necessary.
About the Authors
David Avery, CDT, TE
Director of Professional Services
Drake Precision Dental Laboratory
Charlotte, North Carolina
Larry R. Holt, DDS
Director of Clinical Education and Research
Drake Precision Dental Laboratories
Charlotte, North Carolina
University of North Carolina School of Dentistry
Chapel Hill, North Carolina
David Little, DDS
Adjunct Clinical Professor
University of Texas Health Science Center
San Antonio, Texas
San Antonio, Texas