Conventional fabrication of metal based removable partial dentures relies on manual metal casting, which is inefficient due to labour intensiveness and technique sensitivities. Dr Yu Na and Dr Phang Zi Ying from the National Dental Centre Singapore share the development of a new smart digital workflow for RPDs.

The National Dental Centre Singapore (NDCS) has developed a new smart digital workflow known as SmartRPD, aimed at significantly improving fitting accuracy and reducing treatment time for patients requiring metal base removable partial dentures (RPDs). 

Since 2020, NDCS has been collaborating with A*STAR’s Institute of High Performance Computing (IHPC) on the development of SmartRPD. IHPC developed computational geometry algorithms to analyse patient-specific dental scans and generate 3D models of the RPD frameworks. This user-friendly modelling process requires minimal input from dentists, automating customisation and streamlining manufacturing through 3D printing.

This initiative received joint support from Temasek, which provided the initial philanthropic funding to enable research and technology development for proof-of concept; Temasek Foundation, which provided additional funding for the later stages to establish key platforms and processes for clinical workflows, communications and 3D printing of the RPDs; and the Singapore Ministry of Health through the National Medical Research Council (NMRC) Office, MOH Holdings which supported the clinical team in evaluating clinical efficacy. 

The new SmartRPD workflow integrates intra-oral scanning, automatic design, and 3D printing, transforming the process of the production of RPDs into an automated and streamlined workflow.

SMARTRPD 

Digital workflow and clinical trials

Tooth loss is associated with ageing with negative consequences on general health. 

These consequences can impact a person functionally through impaired chewing and poor nutrition, systemically with links to diabetes and cardiovascular diseases, psychologically causing different forms of speech impairments, and socially affecting the appearance of an individual.

Edentulism is one of the most widely prevalent conditions worldwide. It is estimated that 30% (270 million) of those aged 65 above in the global population have complete edentulism, while 69% (621 million) have partial edentulism.

A 2017 community survey in Singapore found that 69% of elderly aged 65 and above wear dentures.5 Of this figure, nearly two-thirds of seniors have severe tooth loss and 3% of seniors have no teeth. On average, only 11 teeth remain among seniors in the community. In contrast, a healthy dentition requires at least 20 functional teeth. 

Singapore’s ageing population indicates an increase in dental care needs, including the potential demand for RPDs, which typically require replacement every 5-10 years. In 2020, the annual demand for RPDs in Singapore was estimated at 40,000, which may continue to increase as 24% of the population is projected to be 65 and above by 2030.

The SmartRPD proposal was inspired by lead principal investigator assistant professor Dr Yu Na, NDCS, to improve patient outcomes and addressing inefficiencies in the care of RPD treatments.

By integrating digital technology, the goal was to simplify and streamline the process for both clinicians and patients which involved multiple visits under the traditional workflows of RPDs for elderly patients and caregivers.

Based on average numbers from internal data at NDCS, the traditional workflow for RPDs took up to 3-5 visits, depending on the complexity of the case. These visits involved a five-step process including diagnosis analysis, tooth prep design, framework try-in MMR, aesthetic try-in, and final fitting.

The multiple stage workflow and manual fabrication are key hurdles for RPD treatment. The total time to fabricate one RPD framework case is about 11 hours while a 2–4-week turnaround is required between the tooth prep design stage and the dental lab. 

The new SmartRPD workflow developed relies on automatic and digital tools such as intraoral scans, CAD/CAM, and 3D-printing to improve the efficiency and quality of RPDs. The five-step process is reduced to three steps: Scan and design, aesthetic try-in, and final fitting.

The pilot clinical trial of the new digital workflow saw a satisfaction rating of 95% from dentists and demonstrated increased productivity for clinicians. Between 2020 to 2023, multiple trials involved 33 NDCS clinicians, five private dentists, and 90 patients who participated in the scan, digital design, and 3D print workflow.

In the initial visit, users are presented with a proposed 2D template design supported with a digital library of components to suit customisation changes. In the event where the patient has preference than the proposed design, the SmartRPD operator can proceed to add/remove any components. An instant generation of a 3D RPD framework based on the 2D conceptual design is presented to the users allowing the 3D file to be ready for printing.

With the fully digital workflow, accurate annotation and comments from clinical user enables accurate transfer of design correction to designer and lab production. 

Using selective laser melting (SLM) techniques to mass produce chrome cobalt framework precisely, the total time taken to fabricate 30 RPD framework cases was three hours.

For patients, the reduced lead time means they will receive their RPDs much sooner with fewer steps in the community, enabling earlier treatment and enhancing their overall experience. Additionally, with fewer clinic visits required, the burden on elderly patients, particularly those with mobility issues, will be alleviated. 

Moreover, from a healthcare provision perspective, these improvements have the potential to increase capacity at NDCS. As a specialist centre, NDCS specialists would have more time to spend on complex cases and more complicated dental conditions overall.

Patient Case

A patient-case from the clinical trial was presented which reported assuring feedback to the quality and patient experience with the new device and workflow.

The 65-year-old female patient wanted to redo her upper dentures as they no longer fit due to the extraction of two teeth and joined the SmartRPD clinical trial in November 2023 for upper denture fabrication with NDCS dentist Dr Phang Zi Ying. 

The technology used in this case included SmartRPD intraoral scanning, SmartRPD design software and 3D printing where the workflow comprises four steps: Intraoral scanning for precise digital impressions, design of RPD framework using SmartRPD, 3D printing of RPD framework, and final fitting and adjustments.

Dr Phang highlighted the main benefit of SmartRPD is that it allows the clinician to evaluate the patient’s teeth and occlusion chairside. This provides an opportunity to view the teeth from all angles and changes to the denture design can also be decided at the same time. This helps to reduce the number of clinical visits required for denture fabrication. 

As an experienced denture user, the patient remarked that the dentures fabricated using the SmartRPD workflow was her fourth and best fitting device, having worn dentures since the age of 18. While her old dentures used to be uncomfortable and sometimes caused pain when eating, the new device allowed her to chew and enjoy her food thoroughly because of a proper fit.

While the initial appointment took a longer time compared to conventional workflows, the patient also able to receive her dentures quickly and conveniently, with less physical trips to the dentist needed.

The patient was also comfortable with the intra oral scans required for the SmartRPD workflow and experienced little discomfort from the process, reporting that intraoral scans were less uncomfortable than mould impression which can sometimes cause a gag reflex. 

She concluded that the new technology would be appreciated by elderly patients like herself who would also like to receive well-fitting dentures in a timely manner.

SmartRPD Follow-Up 

NDCS will be moving to the next stage to secure clinical validation of SmartRPD from this year. This will involve an additional 300 patients and 40 clinics.

Plans to license this technology are also underway. NDCS is currently in discussions with potential industry partners to commercialise this technology. In addition, NDCS is also leveraging its specialist training programme to familiarise general dentists and specialists with the new technology, to ensure seamless integration of SmartRPD into clinical practice.

Another objective is to ensure that general dental practitioners become familiar with these digital tools, preparing them for future transformations in dental service delivery. Since this technique will be more standardised, more general dental practitioners could use it to serve patients instead of just limiting it to specialists, which would expand the service provision overall.

Overall, the SmartRPD workflow will not only boost operational efficiency but also improve patient satisfaction and access to dental care. 

The article from Dental Asia can be accessed here.