New Material Options for Innovation in Restorative and Prosthetic Dentistry

2011 New Material Options for Innovation in Restorative and Prosthetic Dentistry

New Material Options for Innovation in Restorative and Prosthetic Dentistry Crowns and Bridges PEEK Based Polymers for Dental In-Vitro Fracture Resistance of Three-Unit Fixed Dental Prostheses PEEK 3-Unit Bridge Wear Resistance to In-Vitro Ageing Compressive Fracture Load of 3-Unit Bridges with Different Connector Sizes Compressive Fracture Load of Molar Crowns Veneering Systems Cement System and Surface Preparation of PEEK Substructures CAD/CAM Machining Tool Life Polymer Typical Mechanical Properties (Granular) Polymer Physical Properties Colour and Radiolucency Acknowledgements Key Literature Overview

New Material Options for Innovation in Restorative and Prosthetic Dentistry Invibi Biomaterial Solutions develope and launched its flagship biomaterial PEEK-OPTIMA - the first-ever advanced thermoplastic biomaterial to be used in implantable medical devices in 1999. Over 3 million medical devices now benefit from a set of unique properties that have been utilised in spine, orthopaedic and sports medicine applications. Invibio s PEEK materials have been successfully used by world leading dental companies in applications such as healing caps and temporary abutments due to its mechanical strength, aesthetic qualities, soft tissue response and the ability to shape PEEK easily. However the long term biocompatibility of PEEK means that the material can provide solutions in a wider range of implant applications within restorative and prosthetic dentistry.

Crowns and Bridges Mechanical properties and biocompatibility for permanent metal-free crowns and bridges Veneer repair without the need for crown removal and natural tooth loss Allows diagnostic treatment without substructure removal Material stiffness aimed at improving comfort with excellent preservation of antagonist natural tooth The present document provides technical information and guidance to the dental device manufacturer and dental practicing regarding the use of PEEK based polymer for dental crowns and bridges permanents.

PEEK Based Polymers for Dental PEEK-OPTIMA offers exceptional product purity, quality testing and control. Invibio provides assurance agreement, guaranteeing its long term specification and production methods. Its proven biocompatibility and biostability is supported by US FDA Drug & Device Master files and thousands of regulatory approved implantable devices. In fact, no other implantable PEEK is as extensively used in US FDA, CE-marked and other regulatory body approved devices. Invibio have been optimising the properties of PEEK based materials for permanent crowns and bridges. Shapes for CAD/CAM have been successfully injection moulded. Its ability to be machined from a block using a Cerec milling machine has been determined. We have generated the following information, necessary to provide guidance towards dental substructure and cement and veneer system selection.

In-Vitro Fracture Resistance of Three-Unit Fixed Dental Prostheses PEEK dental three unit fixed prostheses showed excellent performance during in-vitro investigation. No damage occurred to the frameworks or decementations were observed during the prolonged chewing simulation time used to simulate oral stress conditions equivalent to 5 years intraoral use. PEEK restorations have greatly exceed the fracture resistance required to withstand masticatory forces assumed for anterior (300N) and posterior regions (500-600N) Behr et al. 2001, Clinical Oral Implants Research 12: 174-178. Therefore PEEK substructures could be used in clinical applications. PEEK Dental 2055 Zirconia Y-TZP * 1331 Alumina Strengthened with Zirconia ** Glass-Infiltrated Alumina ** Lithium Dislicate Glass Ceramic *** 659 770 950 0 500 1000 1500 2000 2500 Fracture Force (N) * Kolbeck et al. 2008, Clin. Oral Impl. Res., 19: 1049-1053 ** Beuer et al. 2008, European Journal of Oral Sciences, 116: 381-386 *** Scientific Documentation IPS e.max Ceram, Ivoclar Vivadent Literature values are of a comparative nature, but were not tested under the exact same conditions. The CAD/CAM milled PEEK frameworks were cemented on to PMMA models using commercial available Dentsply Calibra Esthetic Resin Cement. The frameworks were veneered with 3M ESPE Sinfomy TM Indirect Lab light-curing Composite. After 24h of storage in 37 distilled water the marginal areas were cleaned and polished and transferred to the chewing simulation. The dentures were aged using a human molar as antagonising tooth with 1.2x10 6 mechanical loads of 50N and 6000 alternating thermal cycles of 5 and 55 C. This simulation is expected to have comparable effects to 5 years of intraoral stress. Krejci et al. 1990, Schweizer Monatsschrift Zahnmedizin 100:8-4; Rosentritt et al. 1977. Materialprϋfung, 39:77-80. All restorations survived and were mechanically loaded until failure in a universal testing machine (Zwick, Germany). Force was applied in the pontic centre using a steel ball and a tin foil to avoid force peeks at the cusp tips. Fracture force (N) was recorded.

PEEK 3-Unit Bridge Wear Resistance to In-Vitro Ageing In contrast to ceramic and metal materials it was shown that PEEK dental 3-unit bridge substructures were not weakened by in-vitro ageing. Results below show that PEEK 3-unit bridge fracture resistance was maintained even after chewing simulation. 2000 Fracture Force (N) 1500 1000 500 0 No Ageing Aged No Ageing Aged No Ageing Aged No Ageing Aged PEEK Dental Y-TZP Zirconia * Alumina Srengthened with Zirconia * Glass-Infiltrated Alumina * * Beuer et al. 2008, European Journal of Oral Sciences, 116: 381-386 Literature values are of a comparative nature, but were not tested under the exact same conditions. CAD/CAM milled PEEK based dental polymer 3-unit bridges were cemented on to PMMA models (Dentsply Calibra Esthetic Resin Cement) and exposed to thermal cycling and mechanical loading (TCML: 6000x5 C/55 C; 1.2x10 6 x50 N). Fracture force was measured using a universal testing machine (Zwick, Germany).

Compressive Fracture Load of 3-Unit Bridges with Different Connector Sizes In order to provide guidance towards bridge design and morphology, 3-unit bridge PEEK substructures with different connector dimensions were tested for compressive fracture load. All PEEK substructures showed high fracture resistance demonstrating its potential for clinical use even with small connector dimensions. Bridge Connector Size (mm) 15 12.3 10 1411 1534 1783 0 500 1000 1500 2000 Fracture Force (N)

Compressive Fracture Load of Molar Crowns Un-veneered and veneered (3M ESPE Sinfomy TM Indirect Lab Composite) PEEK crowns were bonded on to identical epoxy resin models and subject to compressive loading to simulate clinical conditions. PEEK crowns were shown to withstand very high compressive loads. PEEK Dental Substructure Max PEEK Dental Veneered Restoration Glass Infiltrated Alumina * Min 2070 Max Leucite Reinforced Ceramic * Max Lithium Dislicate Glass Ceramics ** Feldspathic Ceramic ** Min Max Max 0 500 1000 1500 2000 2500 3000 Fracture Force (N) * Knowles et al 1998, J Mat Sci: Materials in Medicine, 9: 555-559 ** Scientific Documentation IPS e.max CAD, Ivoclar Vivadent Literature values are of a comparative nature, but were not tested under the exact same conditions.

Veneering Systems Standard techniques were used to fabricate restorations from the PEEK based dental polymer substructures. Good results were obtained using a range of commercial available veneering composites. In the case of veneer chipping, PEEK substructures can allow repair without the need for crown or bridge replacement. PEEK/3M Espe Filtek Z250 242 PEEK/Voco Admina Ormocer 219 PEEK/3M Espe Filtek Silorane 160 Zirconia Y-TZP Min Max 0 50 100 150 200 250 Bi-axial Flexural Strength (MPa) * Beuer et al. 2008, European Journal of Oral Sciences, 116: 381-386 Literature values are of a comparative nature, but were not tested under the exact same conditions. Please contact Invibio Ltd if looking for additional veneer systems.

Cement System and Surface Preparation of PEEK Substructures Restorations fabricated with PEEK based dental polymer can be cemented using a range of commercial available systems. The internal configuration of the PEEK substructure should be roughened using a diamond bur and degreased using acetone. This procedure will increase the bond strength of the PEEK dental material and the luting systems. PEEK/Calibra Esthetic Resin Cement, Dentsply 21.1 PEEK/Rely X Unicem Aplicap, 3M ESPE PEEK/Panavia 21 EX, Kuraray Dental Zirconia Y-TZP * Min 11.8 11.2 Max 0 5 10 15 20 25 Bond Strength (MPa) * Kumbuloglu et al. 2006, Operative Dentistry, 31-2: 248-255; Özcan et al. 2008, Clin Oral Invest, 12: 279-282 Literature values are of a comparative nature, but were not tested under the exact same conditions.

CAD/CAM Machining Tool Life PEEK dental injection moulded shapes allow CAD/CAM milling of dental substructures with reduced tool wear and improved margin control allowing for tight fit restorations. PEEK blocks can be successfully machined using a CEREC milling machine and standard burs. For the CEREC milling of PEEK blocks, the machine can be set up as if to mill either CadWaxx or InCerami alumina blocks. Even after 50 (fifty) PEEK 3-unit bridges have been milled, there was no need to change CEREC milling bur. PEEK Dental Tool Life Ceramics 0 10 20 30 40 50 3-units Bridges Milled Polymer Typical Mechanical Properties (Granular)* Property Method Units PEEK Based Polymers for Dental Flexural Strength ISO 178 MPa 320 Flexural Modulus ISO 178 GPa 20 Tensile Strength (at yield) ISO 527 MPa 190 Young s Modulus ISO 527 GPa 19 Compressive Strength ISO 640 MPa 240 Tensile Elongation (at break) ISO 527 % 1.0 Notch Izod Impact ISO 180 kj/m 2 8 * Testing performed on direct injection moulded sample. Please contact Invibio Ltd for flexural strength properties according to ISO 10477

Polymer Physical Properties PEEK polymers present high chemical resistance with extremely low levels of extractables and leachables, allowing for excellent in-mouth stability and inertness. PEEK displays very low thermal conductivity and is electrically non-conductive, providing excellent in-mouth natural feel. PEEK s excellent strength to weight ratio provides low weight substructures, improving comfort. Patients have reported natural mouth feeling and no foreign object sensation when using PEEK based dental solutions. Property Method Units PEEK-OPTIMA Dental Density ASTM D792 g.cm -3 2.0 Colour and Radiolucency PEEK polymer is naturally radiolucent and compatible to imaging techniques such as X-ray, MRI and Computer Tomography (CT). PEEK dental polymer radiolucency allows clinical diagnostics and treatment through PEEK substructure without need for substructure removal and replacement. PEEK is available in natural and white for improved aesthetics.

Acknowledgements The in-vitro fracture resistance of PEEK based dental polymer three-unit fixed dental prostheses work was conducted in collaboration with C. Kolbeck and M. Rosentritt at the Regensburg University Medical Centre, Department of Prosthetic Dentistry, Regensburg, Germany. The compressive fracture load of PEEK based dental polymer crowns and three-unit fixed dental prostheses, veneer system and cement system testing, surface preparation of PEEK substructures and CAD/CAM machining guidance was conducted in collaboration with D. Wood and A. Johnson at the University of Sheffield, School of Clinical Dentistry, Sheffield, UK.

Key Literature Overview PEEK-OPTIMA Polymer Materials in Dental Applications This summary provides a sample of the most recent and historical literature pertaining to PEEK polymer in dental clinical evaluations Paper Key Findings Effect of different surface pre-treatments and luting materials on shear bond strength to PEEK Schmidlin PR, Stawarczyk B, Wieland M, Attin T, Hämmerle CH, Fischer J. June 2010, Dental Materials The study shows that strong bonds can be achieved between PEEK and dental resin composites. Observations suggest that the pretreatment of the PEEK surface greatly improved its adhesion to the hydrophobic bonding agent tested. The results demonstrate potential for the use of PEEK in dentures and encourage further research in PEEK application in dentistry. Bonding of Polyetheretherketone (PEEK) for Indirect Restorations Wood DJ, Johnson A, Van Noort R, Sereno N. March 2011, International Association of Dental Research In this study the bound strength to reinforced PEEK polymer aimed at use in dental crown and bridges was tested using a range of commercial available cement composites. Each of the three cement systems showed good bond strength to the PEEK material samples with Dentsply Calibra Esthetic Resin Cement resisting to higher loads.

Fracture Strength and Failure Mode of Maxillary Implant-Supported Provisional Single Crowns: A Comparison of Composite Resin Crowns Fabricated Directly Over PEEK Abutments and Solid Titanium Abutments Santing HJ, Meijer HJ, Raghoebar GM, Ozcan M. December 2010, Clinical Implant Dentistry & Related Research The study showed that PEEK abutments provide a viable alternative to titanium abutments for use in the aesthetic zone of the maxilla. It has been demonstrated that PEEK abutments are able to withstand intraoral masticatory forces to a similar level as titanium abutments. PEEK abutments can also be processed in the dental surgery, allowing a chair-side approach, and their white colour makes it easier to achieve a good aesthetic result. A New Transitional Abutment for Immediate Aesthetics and Function Tetelman ED, Babbush CA. July 2008, Implant Dentistry This paper describes how important the choice of the right provisional prosthesis such as the PEEK abutment displaying stable aesthetics and function during the healing phase, is important in maintaining patient s comfort and satisfaction. The PEEK abutment provides a cost effective versatile solution allowing chair-side modification in the dental surgery at the time of implant placement. Furthermore PEEK s proven soft tissue behaviour supports the good recovery of gingival tissue.

SNB Swiss Non-Ligating Bracket. A New and Promising Bracket Karp J. July 2010, ESLO congress, Excellence in Lingual Orthodontics A new bracket solution made from PEEK polymer with two parallel slots allows for a more efficient way of controlling the torque and the enhancement of stability of the buccal segments. As well as therapeutical advantages the PEEK bracket displays low friction resulting in a reduction of treatment time. Metal as connector between implant and prosthetic called in question: The PEEK a new, durable and simple solution Spahn F. October 2010, 46th SFCMFS congress The paper describes the positive benefits of the use of PEEK basal implants and PEEK dental abutments in the clinic. PEEK basal implants proved valuable in clinical cases with low or poor bone levels. PEEK abutments have been successfully used to treat implant failure without the need of implant removal. Nano Hydroxyapatite Coated PEEK Implants: Pilot Study in Rabbit Bone Barkarmo S, Wennerberg AE, Hoffman M, Kjellin P, Stenport V. March 2011, International Association of Dental Research In this study the surface of the PEEK implants was coated with nanocrystalline hydroxyapatite (HA) in order to improve osseointegration to bone tissue. It was shown that PEEK coated with nano HA may be a successful approach to improve osseointegration, however good primary stability is necessary for optimal healing

Osseointegration of one-piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog Koch FP, Weng D, Krämer S, Biesterfeld S, Jahn- Eimermacher A, Wagner W. The study demonstrated that PEEK dental implants survived implantation testing with no indications of damage to the implant. Histomorphometric analysis indicated a positive bone-to-implant contact for PEEK of 27%. March 2010, Clinical Oral Implant Research Surface Modification of PEEK -Parallel Investigations of Primary Human Osteoblast Cytocompatibility and Bacterial Adhesion Poulsson A. April 2010 Scandinavian Society for Biomaterials. The brief exposure of PEEK-OPTIMA to oxygen plasma treatment resulted in an increase in surface energy of the PEEK. Following treatment, primary human osteoblast-like cells demonstrated an increased rate of adhesion to the surface. A corresponding increase in cell functionality was also observed at an earlier time point than that seen on the untreated surface. Taken together, these results suggest that plasma treatment of PEEK may increase its osseointegrative potential. Importantly, such treatment did not increase the susceptibility of PEEK to bacterial adhesion.