Phenotypic Properties of Collagen in Dentinogenesis Imperfecta Associated with Osteogenesis Imperfecta

Salwa Ibrahim,1,* Adam P Strange,2,* Sebastian Aguayo,2,3 Albatool Shinawi,1 Nabilah Harith,1 Nurjehan Mohamed-Ibrahim,1 Samera Siddiqui,2 Susan Parekh,1 Laurent Bozec4 1Department of Paediatric Dentistry, UCL Eastman Dental Institute, University College London, London, UK; 2Department of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK; 3School of Dentistry, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; 4Faculty of Dentistry, University of Toronto, Toronto, Canada*These authors contributed equally to this workCorrespondence: Laurent BozecFaculty of Dentistry, University of Toronto, 124 Edward Street, Toronto ON M5G 1G6, CanadaEmail L.bozec@utoronto.caIntroduction: Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the formation of collagen fibrils in dentin, leading to morphological and structural changes that affect the strength and appearance of teeth. However, there is still a lack of understanding regarding the nanoscale characterization of the disease, in terms of collagen ultrastructure and mechanical properties. Therefore, this research presents a qualitative and quantitative report into the phenotype and characterization of OIDI in dentin, by using a combination of imaging, nanomechanical approaches.Methods: For this study, 8 primary molars from OIDI patients and 8 primary control molars were collected, embedded in acrylic resin and cut into longitudinal sections. Sections were then demineralized in 37% phosphoric acid using a protocol developed in-house. Initial experiments demonstrated the effectiveness of the demineralization protocol, as the ATR-FTIR spectral fingerprints showed an increase in the amide bands together with a decrease in phosphate content. Structural and mechanical analyses were performed directly on both the mineralized and de