IADR Abstract Archives
Full Zirconia CAD/CAM Crowns as Abutments for Removable Partial Denture
Objectives: Combined Prosthetics is the association on the same dental arch of a Removable Partial Denture (RPD) and one or several Fixed Dental Prosthesis (FDP), modified so that RPD metallic framework fits in.
Those modifications are traditionally undertaken by hand-controlled milling machine in a technician-dependant, long, and expensive multi-step process including wax models, metal framework casting and ultimately, porcelain veneering.
Nowadays, computer aided design and computer aided manufacturing (CAD/CAM) milling to modify FDP in order to receive and fit RPD, could be a cheaper and more accurate alternative, particularly on zirconia, because of -inter alia- its resilience and resistance to abrasion.
Thus, the aim of this work was to evaluate digitally milled zirconia crowns for combined prosthetic treatments.
Methods: This work was conducted on a 1-year follow-up study in a teaching hospital: “Groupe Hospitalier Pitié Salpêtrière” in Paris, France (GHPS) where combined prosthetics and CAD/CAM is a daily-practice.
Briefly, after intra-oral scanning (3Shape, København, Danemark), crowns were designed (Exocad, Darmstadt, Germany), then rest seats and RPD counter-parts were substracted (Rhino5 (Cimsystem, Milano, Italy). Crowns were then milled and sealed on abutment teeth. RPD impressions and metallic framework casting were done conventionally before final insertion and correction.
Results: Three clinical cases has been successfully treated, consisting in 3 RPD on a total of 7 zirconia crowns which permitted a controlled path of insertion as well as sustentation and stabilisation for RPD. Retention was a problem on 28% due to poor crown design.
Conclusions: This pilot study proves the possibility to use full zirconia crowns as abutments for RPD. This new CAD/CAM application simplifies combined prosthetic treatments by digitalizing RPD-friendly, crown milling however more specific tools are still needed.
Those modifications are traditionally undertaken by hand-controlled milling machine in a technician-dependant, long, and expensive multi-step process including wax models, metal framework casting and ultimately, porcelain veneering.
Nowadays, computer aided design and computer aided manufacturing (CAD/CAM) milling to modify FDP in order to receive and fit RPD, could be a cheaper and more accurate alternative, particularly on zirconia, because of -inter alia- its resilience and resistance to abrasion.
Thus, the aim of this work was to evaluate digitally milled zirconia crowns for combined prosthetic treatments.
Methods: This work was conducted on a 1-year follow-up study in a teaching hospital: “Groupe Hospitalier Pitié Salpêtrière” in Paris, France (GHPS) where combined prosthetics and CAD/CAM is a daily-practice.
Briefly, after intra-oral scanning (3Shape, København, Danemark), crowns were designed (Exocad, Darmstadt, Germany), then rest seats and RPD counter-parts were substracted (Rhino5 (Cimsystem, Milano, Italy). Crowns were then milled and sealed on abutment teeth. RPD impressions and metallic framework casting were done conventionally before final insertion and correction.
Results: Three clinical cases has been successfully treated, consisting in 3 RPD on a total of 7 zirconia crowns which permitted a controlled path of insertion as well as sustentation and stabilisation for RPD. Retention was a problem on 28% due to poor crown design.
Conclusions: This pilot study proves the possibility to use full zirconia crowns as abutments for RPD. This new CAD/CAM application simplifies combined prosthetic treatments by digitalizing RPD-friendly, crown milling however more specific tools are still needed.