PEEK Performance!

The Discovery of PEEK - The Peak of Dental Materials

Introduction

Polyetheretherketone commonly known as PEEK is a tooth coloured as well as synthetic biomaterial that has been used in the field of orthopedics since a very long time. The etheretherketone monomer unit gets polymerised through a complex dialkylation reaction to form Polyetheretherketone. PEEK is found to be a semi crystalline material and has a melting point of 343 degree centigrade. PEEK can be easily modified by a) Prepolymerisation - By the addition of functionalised monomers b) Postpolymerisation - By chemical processes like amination or nitration

Properties

• Young’s modulus : 3.6 GPa
• Tensile strength : 90-100 MPa
• Glass Transition temperature : 143 Celsius
• Melting point : 343 Celsius
• Operating temperature : upto 250 Celsius
• Highly resistant to thermal degradation
• Soluble in conc H2SO4 in room temperature
• Highly resistant to biodegradation

Applications

Being a robust material, PEEK is used in a number of general industrial items including bearings, piston parts and pumps and electrical cable insulators. PEEK is considered as an advanced biomaterial which can be used in medical and dental implants. PEEK is white in colour and exhibits good mechanical properties, as a result it can be easily used in prosthodontics in the fabrication of FPDs and RPDs. Other than this, it is also used as an esthetic orthodontic wire.

PEEK as an Implant Material

Wolffe’s law states that bone remodels according to the force that is applied to it. Stress shielding is hence done by decreasing the amount of bone around an implant to reduce the load on the implant. Finite element analysis of PEEK implants showed that they are capable to induce less stress shielding than that of titanium implants. However, since PEEK dental implants have not been used widely clinically, it is unknown if there is a difference between the bone resorption around PEEK and titanium implants in human subjects. Moreover, a recent FEA study by Sarot et al has suggested that the stress distribution between PEEK and titanium dental implants is almost similar. Animal studies have suggested that PEEK can easily survive for a minimum of 3 years after which it starts inducing localised inflammation. Some specific studies have even showed that there is no such difference in the osseointegration of PEEK and that of the traditional implant biomaterials like that of titanium and zirconia. Some other studies have also not found any huge difference between the bio-inertness of PEEK, titanium and that of zirconia. Taking adequate biocompatibility into consideration, implant healing abutments can be constructed using PEEK. A randomised, controlled clinical trial (RCT) which was conducted by Koutouzis et al. even suggested that there is no significant difference in the bone resorption and soft tissue inflammation around PEEK and titanium abutments.

PEEK as a Removable Prosthesis Material

PEEK is another material that can be used an alternative to PMMA for CAD-CAM restorations. CAD-CAM dentures can also be easily constructed using PEEK. The clasps that have been constructed using PEEK can be used in the anterior abutments as well because it is of tooth colour, but they have lower retentive forces than that of the cobalt chromium clasps. However, due to the better mechanical and biological properties of PEEK, it is most likely to be used to construct dentures in the near future.