A theranostic dental pulp capping agent with improved MRI and CT contrast and biological properties.

Different materials have been used for vital dental pulp treatment. Preferably a pulp capping agent should show appropriate biological performance, excellent handling properties, and a good imaging contrast. These features can be delivered into a single material through the combination of therapeutic and diagnostic agents (i.e. theranostic). Calcium phosphate based composites (CPCs) are potentially ideal candidate for pulp treatment, although poor imaging contrast and poor dentino-inductive properties are limiting their clinical use. In this study, a theranostic dental pulp capping agent was developed. First, imaging properties of the CPC were improved by using a core-shell structured dual contrast agent (csDCA) consisting of superparamagnetic iron oxide (SPIO) and colloidal gold, as MRI and CT contrast agent respectively. Second, biological properties were implemented by using a dentinogenic factor (i.e. bone morphogenetic protein 2, BMP-2). The obtained CPC/csDCA/BMP-2 composite was tested in vivo, as direct pulp capping agent, in a male Habsi goat incisor model. Our outcomes showed no relevant alteration of the handling and mechanical properties (e.g. setting time, injectability, and compressive strength) by the incorporation of csDCA particles. In vivo results proved MRI contrast enhancement up to 7weeks. Incisors treated with BMP-2 showed improved tertiary dentin deposition as well as faster cement degradation as measured by µCT assessment. In conclusion, the presented theranostic agent matches the imaging and regenerative requirements for pulp capping applications. STATEMENT OF SIGNIFICANCE: In this study, we combined diagnostic and therapeutic agents in order to developed a theranostic pulp capping agent with enhanced MRI and CT contrast and improved dentin regeneration ability. In our study we cover all the steps from material preparation, mechanical and in vitro characterization, to in vivo study in a goat dental model. To the best of our knowledge, this is the first time that a theranostic pulp capping material have been developed and tested in an in vivo animal model. Our promising results in term of imaging contrast enhancement and of induction of new dentin formation, open a new scenario in the development of innovative dental materials.

Calcium-phosphate-coated oral implants promote osseointegration in osteoporosis.

Osteoporotic conditions are anticipated to affect the osseointegration of dental implants. This study aimed to evaluate the effect of a radiofrequent magnetron-sputtered calcium phosphate (CaP) coating on dental implant integration upon installment in the femoral condyles of both healthy and osteoporotic rats. At 8 weeks post-implantation, bone volume and histomorphometric bone area were lower around non-coated implants in osteoporotic rats compared with healthy rats. Interestingly, push-out tests revealed significantly enhanced implant fixation for CaP-coated compared with non-coated implants in both osteoporotic (i.e., 2.9-fold) and healthy rats (i.e., 1.5-fold), with similar implant fixation for CaP-coated implants in osteoporotic conditions compared with that of non-coated implants in healthy conditions. Further, the presence of a CaP coating significantly increased bone-to-implant contact compared with that in non-coated implants in both osteoporotic (i.e., 1.3-fold) and healthy rats (i.e., 1.4-fold). Sequential administration of fluorochrome labels showed significantly increased bone dynamics close to CaP-coated implants at 3 weeks of implantation in osteoporotic conditions and significantly decreased bone dynamics in osteoporotic compared with healthy conditions. In conclusion, analysis of the data obtained demonstrated that dental implant modification with a thin CaP coating effectively improves osseointegration in both healthy and osteoporotic conditions.