Material aging abutting restorations: predicting dentine sclerosis

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Within the scope of the research group InterDent, project 1 examines micro/nano structural and chemical attributes of chemically-aged dentine, a natural biomaterial that often becomes sclerotic especially near dental fillings. To predict the dynamics of structural and compositional changes incurred in treated dentine, it is necessary to assess these chemical and material property changes during the process of dentine sclerosis in a quantitative manner. Despite a general improvement in clinical performance of contemporary dental adhesives, less invasive treatment requires knowledge about the state of previously treated, chemically aged dentine that serves as a substrate. We hypothesize that dentine abutting restorations undergoes subtle microstructure and property changes, accumulating with time. We use Zn-containing dental filling materials to explore spatio-temporal aspects of this chemical aging process. With increased gradual chemical aging, the composition within and around tubules changes with some relation to the filling both in terms of composition and with relation to distance along tubules. Within the project and through cooperation between 3 institutes, we use material science methods to quantify changes in the density and mineral attributes of dentine near restorations. High sensitivity 3D XRF methods will be combined with diffraction and imaging investigations to explore changes in chemical composition and mechanical deformability. Various aspects of the transformation of this natural material into a transition 'interzone' that still has mechanical competence to sustain function within restored teeth are being quantified using high resolution 2D and 3D methods. We will elucidate changes in the distribution and chemical state of crucial elements such as Ca - normal constituent of dentine - and Zn - an element primarily introduced into the structure through diffusion processes. Our overall objectives are to develop a dentinal sclerosis model system, to quantify the changes non-destructively with high sensitivity and with high resolution and to correlate results obtained by different analytical techniques. We anticipate obtaining a better materials and clinical understanding about changes in structure and elemental composition which we will compare between model systems to in-vivo developing sclerotic tissue.