Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone

Abstract

Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45 o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p < 0.05). In contrast, no statistically significant difference was observed between the fracture resistance of the PEEK and the 30% carbon fiber-reinforced PEEK screws (p > 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

Polyetheretherketone (PEEK) as a medical and dental material. A literature review

“…Five were clinical reports [2,6,8,18,24] and 35 were papers on PEEK surface treatments [13][14][15][16][17] how the bioactivity of PEEK can be improved [1,21]; the characteristics of CFR-PEEK [3,7,[19][20]; the biocompatibility of PEEK [5]; PEEK applications [4,8,[10][11]30]; PEEK biofilm formation [22,[31][32][33][34], PEEK as an abutment material and as an implant material [12,23,[25][26][27][28][29]35,40] and the use of CAD-CAM with PEEK [36][37][38][39]. …”

“…The most widely used materials used are: titanium, gold, base metals, zirconium or aluminum oxide ceramics. PEEK is currently used as a provisional abutment, because this material has been demonstrated to reduce stress shielding around the implant [23][24][25][27][28]. However, PEEK is not used as a definitive abutment material because its fracture resistance is lower than that of titanium [25,[29][30].…”

“…These include hypersensitivity in the user, excessive stress on the implant-bone due to the gradient of difference in the elastic moduli, as well as certain esthetic problems. PEEK, which was first commercialized in April 1998 as a biomaterial for implants [23][24][25], has been proposed an alternative to titanium.…”

“…Prosthetic abutments made from this polymer can be expected to have improved torque efficiency and they are easier to remove in the event of fracture [25].…”

“…Titanium had a higher fracture resistance compared with the polymers. The fracture location occurred at the neck of the screw [25].…”