Dr. Richard V. Curtis

===> SUPERPLASTIC PROSTHETIC FORMING <===
The manufacture of customized oral and maxillofacial prostheses by Superplastic Prosthetic Forming: surface reconstruction, die modelling, materials' characterization, superplastic forming simulation, manufacture, and experimental validation.

A manufacturing system was developed that allows surfaces of dental models or images from CT scans to be used to reconstruct hard and soft tissues for computer simulation of the superplastic forming process in 2D or 3D for construction of dental and maxillofacial prostheses. The complete manufacturing cycle from patient to fitted prosthesis is currently being investigated and optimised.

We are currently comparing the superplastic forming simulations for a wide range of dental and maxillofacial prostheses using membrane elements and solid elements in the finite element formulation to determine whether unique pressure profiles are required for prostheses.

---> Current PhD project: Surface characterisation of post-formed SPF titanium alloy.

===> LOW COST CERAMIC DIES FOR SUPERPLASTIC PROSTHETIC FORMING <===
Low cost die materials for superplastic prosthetic forming. Here there is a need for low-cost tooling materials that will support the stresses applied when forming titanium alloy sheet during superplastic forming. At the same time, interactions between the forming sheet and the die material are of interest if they result in a more biocompatible titanium surface.

Machined metallic dies, often preferred by other industries, would be too costly for use in the production of dental and maxillofacial prostheses where components are produced on a customized basis. Therefore, dental casting investment materials have been adopted as likely candidates for this application. In order to measure the suitability of such materials it has been necessary to develop tests that provide useful information for prosthesis production and computer simulation. Factors that are of importance include strength, coefficient of thermal expansion and handling techniques to optimize the properties of these materials. Since investment materials are basically ceramics they are prone to failure from the simple presence of flaws. e.g. Porosity introduced during processing can be the cause of failure of the tool. So, two experiments have been devised and the results published in the peer-reviewed literature that describes the effect of porosity introduced during handling. The two tests are based on the production of diaphragms of the investment material that are then subjected to loads at high strain rate, representing casting and at slow strain rate, representing superplastic forming. The tests that were carried out at slow strain rate have been simulated using finite element analysis. These experiments were carried out on material that had been processed using various combinations of vacuum and pressure during mixing and setting. We have determined the critical pore size for the material. We are also investigating possible deformation in slow strain rate test diaphragms. Further work will include the addition of metallic fibers/particulates as reinforcement for these materials for crown and bridge applications.

Ceramic die/titanium sheet interactions are also being investigated to determine the effect of these interactions on the host response for implants produced by superplastic forming. The studies are being carried out in vitro using specific cell lines.

===> FATIGUE PROPERTIES OF DENTAL IMPLANT ASSEMBLIES <===
The mechanical testing of dental implants and dental implant assemblies: fatigue testing procedures are being used to challenge complete dental implant systems mechanically. i.e. the implant + the abutment + the retaining screw. Torque signature analysis is being used to characterise these challenged systems to provide information on different types of failure. This research is currently being conducted at the PhD level by a clinical specialist in implant dentistry in collaboration with the B3 research group (Biomaterials, Biomimetics and Biophotonics).
---> Current PhD project: Developing test methods to determine the mechanical behaviour of dental implant assemblies

===> THE FATIGUE TESTING AND FRACTURE CHARACTERISATION OF MACHINED ZIRCONIA RESTORATIONS <===
Industrial funding has been obtained to provide a bursary for a PhD studentship in this area. The longevity of any ceramic restoration can be attributed to factors including the design of the restoration, the material from which it is made, inherent flaws in the material, surface finish, associated materials from which the restoration is built up, including cement thickness and profile, and processing history. The development of restorations using CAD/CAM and zirconia is currently being exploited by a number of companies, based on the material's high stiffness and it's unique property of transformation toughening and the improvements in machining technologies that now allow this material to be machined in either a green state (adopted by several companies) or in the fully-sintered state (adopted by Renishaw plc). However, the aim of this study will be to identify the major factors leading to failure of a range of complete dental restorations produced using zirconia and associated materials including dental cements and dental porcelains and to provide solutions to limit these failures. A better understanding of the mechanisms of failure will allow this goal to be achieved. The other aim of the project will be to optimise the reliability of such restorations so as to provide the dental practitioner with clear guidance as to the material combinations that are contraindicated and practical procedures that should be followed to enhance longevity. The zirconia will be supplied and machined by Renishaw plc. The loading regimen will be primarily in fatigue and will be carried out using state-of-the-art testing equipment installed in the B3 biomaterials laboratory of the Dental Institute.
---> Current PhD project: Determining the reliability and longevity of machined zirconia restorations.

- Superplastic forming of layered composite structures for biomedical applications including their biocompatibility
- The development of customised maxillofacial prostheses by superplastic forming
- The design of dental superplastic forming equipment for laboratory purposes
- Contactless and contacting scanning for the accurate reproduction of the hard and soft tissues of the mouth for numerical simulation and surface metrology
- The in vitro measurement of the reliability and longevity of ceramic restorations
- Assessment and measurement of tooth wear as result of acid reflux

The work on numerical simulation, experimental validation and material characterisation may be applied to the production of medical devices, and components in the aerospace and automotive industries.

1. POSTGRADUATE COURSES
- As a postgraduate coordinator I am currently responsible for the progression of 15 PhD students supervised in research groups other than my own. In this role my resonsibilities include:
> Advising on admissions/interview panels
> Co-ordinating the relevant pastoral care of PGR students
> General responsibility for PGR students allocated by the Head of Graduate studies.
> Serve on the Postgraduate Research Committee
> Approve offers of places to successful PGR applicants.
> Inform Head of Graduate Research Studies on supervision arrangements and supervisor performance in the division as neccessary.
> Ensure PGR students meet deadlines for submission of annual reports.
> Ensure MPhil/PhD conversion procedures are conducted correctly.
> Approve student progress, and make recommendations to the Head of Graduate Studies on unsatisfactory cases.
> Ensure student participation in prescribed skills development courses.
> Encourage students and supervisors to collaborate successfully in submitting thesis within the prescribed study period.
> Contribute to providing data for records of progression and completion.
> Advise on requirements, and work with School Head of Graduate Studies and academic and administrative staff to provide local facilities for graduate student research and study.

2. UNDERGRADUATE COURSES
- Administering and teaching of dental and biomaterials for undergraduate and postgraduate courses in dentistry
- Administering and teaching of biomaterials for medical and dental students intercalating a B.Sc. Course cooordinator and Chair of the Biomaterials BSc Board reporting directly to the Undergraduate Board of Examiners in Biomedical Sciences.
- Administering and teaching of polymer science for clinical perfusion science course

3. PERSONAL RESEARCH RELATED
- Experience with the design, installation, operation and maintenance of a purpose-built 20-tonne hydraulic superplastic forming press including gas management system and laboratory based data-capture system.
- The selection, handling and use of a wide variety of materials
- The use and interpretation of results of a wide variety of analytical techniques and test methods including scanning electron microscopy, x-ray microanalysis, thermal analysis, x-ray diffraction and electron back-scattering diffraction, creep and tensile and fatigue testing.
- Extensive PC-based computer skills in programming and the use of software for presentations
- The use of software for laser scanning, surface reconstruction and modeling and forfinite element analysis