Prof. Murali Srinivasan
DMD, PhD
• Clinic director, Clinic of General-, Special Care- and Geriatric Dentistry, University of Zurich, Switzerland.
• Bachelor of Dental Surgery, Saveetha University, Chennai, India Master of Dental Surgery (prosthodontics), Saveetha University, Chennai, India.
• Dr. med. dent., University of Geneva, Switzerland
• Master of Advanced Studies (Reconstructive Dentistry) University of Geneva, Switzerland,
• Privat Docent, University of Geneva, Switzerland.
• International team for implantology, Fellow
• Swiss Society of the Gerodontology and Special care dentistry, President
• Geriatric Oral Research Group, IADR, President-elect
• European College of Gerodontology, Past president
In recent years
dentistry has witnessed groundbreaking advancements that promise to enhance the quality of care and improve patient outcomes. CAD/CAM technology has not only significantly streamlined clinical/laboratory processes and reduced the number of necessary dental appointments but also enhanced the overall efficiency of dental practice, promising greater precision and customisation. Integrating CAD/CAM technology into the fabrication of complete dentures stands out as a transformative development but is still in its initial stages of evolution. This technology is not yet ready to surpass traditional methods in routine clinical practice. Despite its potential, several critical challenges limit its widespread adoption and effectiveness.
Conventional methods of creating complete dentures are labour-intensive, requiring multiple patient visits and significant manual skills from both dentists and dental technicians. The process involves impressions, bite registrations, and tryins (with or without numerous adjustments) before the final insertion. All these steps constitute the clinical part, and each one must be supported by a corresponding laboratory procedure that includes model fabrication, articulation, wax-ups, and, finally, the processing itself. While this traditional work- flow is effective and is still considered the ‘Gold Standard’, it requires considerable time and patient vis- its. Although these are necessary to achieve a successful treatment outcome, it may be worthwhile to consider that this might be cumbersome for age-advanced frail older adults.
With the technological advancements and their impact on modern-day dentistry, one would imagine that denture manufacturing would have also become simplified with just a click of a button. With the digital tools present in our armamentarium today, it is theoretically conceivable to manufacture complete dentures by a ‘fully’ digital protocol without using any analogue clinical or laboratory step.
The theoretical digital workflow would involve, as a first step, acquiring optical impressions of the maxillary and mandibular edentulous arches mucostatically while registering their borders in a functional state.
The next step would be to digitally register the jaw relations and the esthetic parameters, thus completing the clinical steps required for manufacturing complete dentures. The registered clinical information would then be transferred to the dental technician, who would import this into a purpose-built software and prepare a digital set-up of the final denture.
The final steps would include generating a preview of the final denture followed by its fabrication. Ideally, the generated preview should be sufficient to receive consent from the clinician and the patient to pro- ceed with the fabrication. The technician then proceeds to fabricate the complete dentures using either an additive (3D printing) or a sub- tractive (CNC milling) method. The two manufacturing methods have their distinct benefits and disadvantages; the clinical situation, clinician/technician preference, patient expectations, and costs, usually determine the choice.
Let us critically examine our conceptualized ‘fully-digital’ workflow.
“The steep learning curve associated with digital complete denture construction is plateauing rapidly.”
THE FIRST STEP: OPTICAL IMPRESSIONS OF THE EDENTULOUS JAWS
THE FIRST STEP: OPTICAL IMPRES- SIONS OF THE EDENTULOUS JAWS
While modern optical devices may accurately capture the maxillary ridge, hard palate and mandibular ridge, they cannot register the peripheral borders, the sulci (labial, buccal and lingual) and the posterior palatal seal in their functional state.
Therefore, the resultant optical impressions will have anatomically incorrect borders that are either thin, short, too long, or too thick. The success of obtaining accurate borders would largely depend on the dentist and the dental technician. The extensions would be an estimate based on the experiences of the operators. Hence, the acquisitions would not suffice as definitive impressions but rather as preliminary ones and would still need to be redone using conventional techniques and materials.
THE NEXT STEP: REGISTRATION OF JAW RELATIONS DIGITALLY?
THE NEXT STEP: REGISTRATION OF JAW RELATIONS DIGITALLY?
This step is currently impossible for an edentulous patient in a wholly digital workflow for a straightforward reason. No face/jaw tracking device can currently capture the movements of the edentulous jaws without an analogue reference because a favourable anatomy or stable structures are not present on the edentulous jaws to directly stabilise the tracking sensors. Perhaps some solutions to stabilise the sensors for the maxillary arch may be innovatively identified, but it is almost impossible for the mandible.
Multiple intermediary steps are necessary to successfully register the centric relation with these tracking devices for an edentulous patient. It must be performed with existing dentures or with denture bases or trial dentures. First, the existing dentures must be quite stable, which usually requires additional procedures to ensure they are retentive during jaw-tracking. If not, new stable denture bases or trial dentures must be fabricated to perform this step. Therefore, digitising this clinical step involves adding supplementary procedures to existing traditional protocols, whereby increasing the treatment time and costs.
THE FINAL STEP: DIGITAL PREVIEW AND FABRICATION
THE FINAL STEP: DIGITAL PREVIEW AND FABRICATION
Perhaps the only ‘true’ digital processes involved in fabricating complete dentures include the generation of a digital preview and the denture fabrication. These final steps can be performed without any analogue processes or conventional materials.
The denture construction software can set up the teeth as per the clini- cal records obtained and generate a preview for approval. This preview may be viewed alone or with the patient’s face scans (if appropriately planned at the start). If changes to the digital set-up are required, they may be incorporated digitally before proceeding to fabrication.
The fabrication process can be executed entirely digitally. However, it is important to remember that the success and predictability of the final steps depend on the precise recording of the initial steps.
“With ongoing education and technological advancements, the integration of CAD/CAM technology into everyday practice will likely become more streamlined and widespread, ultimately benefiting both practitioners and patients.”
SOLUTION
SOLUTION
Although a fully digital protocol is not currently achievable, an ‘analogue-digital’ hybrid clinical protocol guarantees predictable outcomes, ensuring both patient and clinician satisfaction. These suggested protocols primarily exploit the efficiency of conventional clinical steps and blend them with digital processes, resulting in a denture that combines the best of both worlds. In this approach, definitive impressions and jaw relations are recorded using analogue clinical procedures and then digitised. This scan data is used to generate the preview and, subsequently, the denture, resulting in clinically predictable outcomes.
FUTURE PERSECTIVES
FUTURE PERSECTIVES
Promoting the use of CAD/CAM technology for complete denture fabrication is crucial for modern dental practice. Digital dentures offer numerous benefits, including the creation of a digital record, which is invaluable. These records can be used to fabricate duplicate dentures without repeating clinical or laboratory procedures, which is particularly advantageous for elderly patients with limited access to care, such as those living in institutions or in places with no/limited access to dental care. Moreover, digital records can be used to create templates for new dentures, thereby reducing treatment time, clinical procedures, visits, and costs. Even if the dentures are not initially manufactured digitally, it is essential to advocate for scanning existing dentures and storing these digital records as a part of standard patient records. Looking forward, the potential for CAD/CAM technology in denture fabrication is immense.
As the technology continues to evolve, we can anticipate further enhancements in the precision and speed of denture production. Advancements in acquisition tools are expected to address current issues soon, integrating optical impressions and jaw relations seamlessly. Additionally, dentists and
dental technicians are continuously developing new skills to operate complex software and machinery.
The steep learning curve associated with digital complete denture construction is plateauing rapidly. With ongoing education and technological advancements, integrating CAD/ CAM technology into everyday practice will likely become more streamlined and widespread, ultimately benefiting both practitioners and patients.
In conclusion, CAD/CAM technology represents a significant step for- ward in the fabrication of complete dentures. Although the digital tools currently available may not yet offer the possibility of a completely digital workflow for fabricating dentures, constantly evolving technological advancements hold the promise of a solution soon.