3D-printed denture teeth suitable for long-term clinical use

Anisha Hall Hoppe, Dental Tribune International

Thu. 16. February 2023

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DAMMAM, Saudi Arabia: The method of denture fabrication and material used are relevant to longevity, strength and occlusal wear resistance. 3D-printing technology has brought many advancements for complete denture fabrication, but there is a lack of knowledge on the mechanical behaviour of 3D-printed teeth. For this reason, researchers with the Imam Abdulrahman Bin Faisal University in Dammam evaluated and compared the fracture resistance and wear of various brands of 3D-printed denture teeth to those of prefabricated ones. The team determined that the majority of the 3D-printed teeth tested stood up point by point against the prefabricated ones.

As 3D printing has begun to offer fabrication options that are more affordable and less wasteful than traditional subtractive milling methods, corresponding technology in 3D scanning has also enabled researchers to overcome previous limitations in comparing tooth wear across different types of material. For this study, the researchers evaluated 60 3D-printed teeth created using resins from Asiga, Formlabs and NextDent.

The 3D-printed teeth were created from scans and printed in the respective resins based upon the respective recommendations of each manufacturer. Prior to testing, every printed tooth was scanned for a baseline measurement. Each 3D-printed specimen was subjected to 5,000 thermo-cycles, to simulate temperature change in the oral cavity, and those samples selected for wear testing experienced 170,000 cyclic loads in a chewing simulator, representing an average year of use.

For assessing fracture resistance, the team used a testing device with a stainless-steel ball indenteor in contact with each of the four cusps of each 3D printed tooth with a 1.5 mm rubber sheet in between to better distribute the force, loading until failure.

Wear resistance was measured by evaluating volume loss. Teeth created with NextDent resin demonstrated the most significant volume loss compared with other printed teeth and prefabricated teeth, whereas Formlabs teeth exhibited the least. The prefabricated teeth had a marginally higher fracture load than the teeth printed with Asiga and Formlabs resins, but the NextDent teeth demonstrated a much lower load tolerance than all other teeth types.

The team attributed the strength of the prefabricated teeth to their method of fabrication and their glossy coating mimicking enamel that further increased wear resistance. They also noted that the Formlabs teeth likely won out on tests owing to the digital light processing technology used in printing with this resin.

Both Formlabs and Asiga resins were found by the researchers to be suitable for clinical use because their measured values were comparable with those of the prefabricated controls. They recommended that NextDent be further evaluated. The team also suggested that nanoparticle reinforcement could provide increased wear resistance and higher strength to resin teeth, in much the same way that denture base resins were reinforced with zirconia or silica nanoparticles.

The study, titled “Strength and wear behavior of three-dimensional printed and prefabricated denture teeth: An in vitro comparative analysis”, was published online on 20 January 2023 in the European Journal of Dentistry, ahead of inclusion in an issue.