In terms of the load-cushioning capacity of the prosthetic elements, the use of PEEK as a prosthetic structure on implants has increased in recent years [14]. PEEK is a high-density thermoplastic polymer with a linear aromatic semi-crystalline structure that has exceptional physical and chemical properties as regards toughness, hardness and elasticity. Also, its low molecular weight, combined with the absence of metal, allows its use as excellent biocompatible prosthetic denture material.

PEEK has a modulus of elasticity (E-modulus 4 GPa) great overdenture implants compared to other conventional materials such as titanium (E-module 110 GPa) or zirconium dioxide (E-modulus 210 GPa).

In addition, the bending resistance of metal-ceramic restorations stands at around 400 to 600 Mpa. [15], in contrast to new composite coatings that have a Vickers hardness of approximately 400 MPa and a bending capacity of 314 MPa. Conversely, zirconia is three times harder (1200 HV) and its resistance to bending is 1400 Mpa [16].

As a whole, all of these features mean that the use of materials of high rigidity will result in direct transmission of chewing forces to the zirconia implant. This potential overload could cause bone reabsorption around the implants [17]. Some authors claim that this relation only exists in cases accompanied by a previous inflammatory process (of infectious origin), [18] where bone loss would be accelerated.

To avoid exceeding the adaptive limits of the bone and maintain the proper stimulation of mechanical stress that will keep the bone vital [19], PEEK components seem a viable alternative to obtaining a similar modulus to that of cortical bone. In this way, bone could be stimulated, favouring remodelling without overload [20]. It would concentrate the load by absorbing and distributing the same [21]. Its capacity of load absorption has led some authors to recommend its use in patients with severe bruxism [22].

Finite element analysis suggests that maximum contact pressure at the bone-titanium implant interface can be significantly reduced by using a PEEK crown rather than a ceramic crown [23].