Effective low-cost high-resolution replicas for light scanning and topographic analysis of dental crown

From the 18th International Symposium on Dental Morphology 3rd Congress of the International Association for Paleodontology When performing high-resolution replicas, there are a large several options of casting materials depending on the techniques used for analysis. In this contribution we will address casting materials aimed to the reconstruction of 3D virtual models using a high-resolution surface scanning system. For acquiring the 3D model, we use an intraoral scanner i500 Medit (Staumann Group), designed for dentistry. It is capable of accurately record the surface with a precision of 3.2 microns ± 0.49. Transparent epoxy resins are the most commonly material used, which must be coated with talcum powder or ammonium chloride fog providing an opaque appearance that allow scanning, obstructing the posterior use of the replicas with other methodologies, for example, microwear analysis. Another practice is to use dental stone which allow a fast and low-cost replication but a poor performance regarding reproduction of the details. With an increase of accuracy and trueness in scanning, we are needing more reliable materials than can replicate the details preserved on the mold. Polyurethane resins have been demonstrated to have great precision (i.e., dental microwear), and are low-cost compared to epoxy resins. We tested four different types, based on their curation time from few minutes to 2-3 hours. The performance under the scanner was similar in all cases. The process of producing the replica is what separate them. Polyurethane generates an exothermic reaction while curing, and the fastest the process is, the highest temperatures are reached, to the point of even damaging the molds, erasing some of its details. If the resin cures within 2-3 hours, no damage has been observed on the mold, and it can be re-casted without appreciating any difference. The advantages of using this material over epoxy resin are the low-cost, excellent reproduction of the details also allowing studies on morphology, analyses with optical microscopes, SEM, etc.
This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 891529. Book of Abstracts published in the Bulletin of the International Association for Paleodontology www.paleodontology.com