PhD Position – Biomat

About the position Applications are invited for a 100% full-time, three-year PhD Research Fellowship at the Department of Biomaterials (BIOMAT), Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo (UiO), Norway. - The preferred starting date is as soon as possible, or by agreement. The position is linked to the funded project “Wear and Fracture Testing Models for Dental Crowns: From Oral Tribology to 4D Micro-CT Failure Analysis”. The laboratory-based project combines dental biomaterials, development of wear-testing methods, mechanical characterisation and advanced X-ray imaging, with collaboration in restorative dentistry/prosthodontics and experimental mechanics. More about the position Project title: Wear and Fracture Testing Models for Dental Crowns: From Oral Tribology to 4D Micro-CT Failure Analysis Dental crowns are fabricated from conventional ceramics, lithium silicate/lithium disilicate, resin composites, hybrid CAD/CAM materials and newer additively manufactured materials. Independent evidence on the long-term wear, antagonist wear and failure mechanisms of 3D-printed crown materials remains limited. Clinically relevant testing must therefore consider cyclic loading, sliding contact, saliva, temperature, antagonist material, specimen geometry, surface finishing and loading duration. The overall aim is to develop a clinically relevant wear and fracture testing protocol and use it to compare wear rates, antagonist interactions and failure mechanisms of conventional and emerging crown materials. Building on the Oslo wear model, the project will adapt wet abrasion testing from composite fillings to full-crown and crown-like specimens tested against defined natural or restorative antagonists. The project is organised into three interlinked work packages: 1. Development and validation of a clinically relevant oral wear protocol. Establish a reproducible protocol using defined antagonists, saliva-based media, controlled temperature, cyclic force, sliding contact and staged loading intervals. Natural enamel, composite and ceramic antagonists, as well as flat reference and selected anatomical specimens, may be evaluated. Outcomes include volumetric wear, vertical loss, surface roughness and antagonist wear. Validation will address reproducibility, sensitivity and ranking ability using micro-CT and complementary surface-based measurements. 2. Comparative wear analysis of crown materials and material combinations. Compare selected 3D-printed crown materials with established CAD/CAM resin-composite or hybrid materials and ceramic references, including lithium silicate/lithium disilicate where relevant. Materials will be processed according to applicable instructions. Staged testing will assess crown and antagonist wear, local wear patterns, surface degradation, defects, crack formation and the influence of clinically relevant material combinations. 3. Micro-CT and 4D tomography of damage accumulation and fracture behaviour. Representative materials from the wear study will undergo mechanical loading and non-destructive imaging before loading, at defined intervals and after fracture. Ex situ micro-CT will investigate internal defects, crack initiation and propagation, and links between prior wear and final failure. Where feasible, 4D tomography and digital volume correlation will quantify deformation and strain localisation in collaboration with Lund University. The project will examine printing direction, post-curing, anisotropy, and layer-related defects in additively manufactured crowns. The project uses a staged design: protocol development and comparative wear screening are followed by detailed analysis of selected materials. If 4D tomography or digital volume correlation is limited by access or image quality, repeated ex situ micro-CT during interrupted loading is the predefined fallback. The three-year project is expected to produce three scientific papers and a doctoral thesis. Your areas of responsibility will be - Plan, standardise and conduct laboratory experiments in accordance with the approved project, relevant ethical approvals and the data-management plan. - Prepare, manufacture and finish 3D-printed, CAD/CAM and ceramic crown materials, crown-like specimens and antagonist specimens according to defined protocols and manufacturers’ instructions. - Develop and validate the oral wear-testing workflow, including antagonist configuration, saliva-based test media, temperature, cyclic load, sliding path, cycle intervals, calibration, quality control and reproducibility. - Perform wear testing, surface characterisation, mechanical loading, micro-CT imaging and quantitative image analysis, with appropriate training and supervision. - Contribute to selected 4D tomography and digital volume correlation experiments with external collaborators where access, specimen design and image quality permit. - Analyse longitudinal and group-comparison data using transparent and reproducible statistical workflows. - Write scientific papers and a PhD thesis, present results at national and international meetings, and contribute constructively to the scientific and social activities of the Biomaterials group. More about the fellowship The purpose of the fellowship is research training leading to the successful completion of a PhD degree. The appointment is for three years and is devoted to the doctoral project and required research training. Admission to the PhD programme at the Faculty of Dentistry is a prerequisite for taking up the position. The candidate is expected to complete the project within the fellowship period. A final plan for the research training must be approved and formalised no later than three months after the start of the position. The main supervisor will be Professor Håvard J. Haugen. The project combines expertise in dental biomaterials, development of wear-testing methods, restorative dentistry/prosthodontics, dental material processing, sur