Bending moments of PEEK-based root analog implants (RAIs)

Root-analog implants are frequently fabricated from titanium, which can be associated with various problems, e.g. hypersensitivity to titanium. In this study, we evaluate the bending moments of different polyetheretherketone-based root analog implants as a metal-free alternative. For this, an extracted tooth 31 and 36 was scanned to create an STL data set of each tooth. These were used to fabricate n = 8 polyetheretherketone-based root analog implants per group, with 5 groups being fabricated per tooth type. Two groups were additively manufactured using material extrusion. The other groups were milled from differnet polyetheretherketone grades. After artificial ageing, the samples were statically loaded until fracture in order to determine the bending moment. Of the root analog implants in the form of a 31, a white, milled polyetheretherketone grade showed the highest bending moment of 2835.3 ± 509.8 Nmm and an unfilled, additively processed polyetheretherketone grade the lowest. Of the RAIs in the form of a 36, an unfilled, milled polyetheretherketone grade showed the highest bending moment with 29342.6 ± 854.7 Nmm and a white, additively processed polyetheretherketone grade showed the lowest bending moment with 19880.5 ± 7188.6 Nmm. Basically, the results between the additively and subtractively processed groups were significantly different. In terms of mechanical requirements in the oral cavity, one-piece milled polyetheretherketone -based RAIs appear to provide more predictable results than additively manufactured ones. Taken together, our study suggests that more solidly designed one-piece root analog implants made of milled polyetheretherketone in the form of molars appear to be able to withstand the mechanical requirements of the oral cavity.