Digital Technology for the Production of Removable Partial Denture Metal Frameworks

Abstract

Objectives: To review the fit accuracy results of removable partial dentures (RPDs) metal frameworks produced by different digital protocols. To evaluate methods for the fit accuracy assessment of RPD metal frameworks to the supporting structures. To clinically evaluate RPD metal frameworks produced by digital technology. Materials and methods: A systematic review was elaborated to identify the digital protocols of framework production and the corresponding fit accuracy assessment previously described. In vitro study of direct (digital superimposition and inspection) and indirect (mold thickness measure by micro-computed tomography) assessment of the gap between the occlusal rests (n= 34) and their respective rest seats. For twenty-six dental arches (n= 26) two RPD Co-Cr frameworks production protocol (experimental digital vs conventional lost-wax) were compared for production repetition, components adjusted until correct insertion, clinical acceptability, components maladjustment and thickness and volume of occlusal rest silicone molds determined by micro-computed tomography. Data were analyzed using adequate parametric or non-parametric tests (α= 0.05). Results: The most described protocol was the direct additive manufacturing using conventional impression, which showed better outcomes. A strong positive correlation (ρ= 0.612) between quantitative methods was verified and no difference (p = 0.595) was found between the qualitative data. Digital production protocol presented similar results than control, with the exception of lower production repetitions (p= 0.046), higher components adjusted (p= 0.011) and lower reciprocal arms maladjustment (p= 0.044). Conclusions: The results of this thesis suggest that the direct additive manufacturing using conventional impression is a feasible method to produce RPD metal frameworks, considering the applyed assessment methods.