From October 1st to 5th the annual meeting of the Academy of Dental Materials (ADM) was held in Jackson Hole (Wyoming, USA), entitled: "Materials to Enable the Evolution/Revolution of Digital Dentistry" (for more details read the article: http://www.dentistry33.com/dentistry33/editorials/142/academy-of-dental-materials-annual-meeting-2019.html )
During this meeting, ADM offers “Marshall Postdoctoral Award” in recognition of excellence in dental biomaterials research.The primary purpose of the award is to encourage and recognize outstanding research performed by individuals in the transitional post-doctoral stage of their careers.This award was created in honor of Grayson and Sally Marshall, who have excelled in mentorship roles and have made great contributions to the ADM during their careers. Both have been Fellow members of the ADM since 1983 and are currently Emeritus members.
This year, we are very glad to announce that the award went to Dr. Andrei C. Ionescu (University of Milan, Italy), with is research entitled: "Antimicrobial properties of PMMA resin containing graphene (A.C. Ionescu, S. Sauro, P.M. Pires, A. Lòpez-Castellano, A.M. Alambiaga-Caravaca, E. Brambilla)".
Here below you can find the abstract of his research:
Modern prosthetic dentistry is increasingly focusing on digital procedures, including CAD/CAM technologies. In this context, PMMA is being widely employed as material for prosthetic and restorative devices. Secondary caries is still the main reason for the failure of dental resin-based restorations. Therefore, an antimicrobial activity expressed by these materials is regarded as beneficial for their longevity. This study aimed to test the physical, chemical, and microbiological behavior of a PMMA resin for CAD/CAM applications containing graphene.
Materials and methods: Specimens (n=48) were made from<50ppm graphene-containing PMMA disks and from conventional PMMA disks for CAD/CAM applications. Specimens were finished with abrasive paper up to 4000 grit, and a half was subjected to soaking in absolute ethanol for 24 h. This protocol was introduced to evaluate the microbiological behavior of the tested samples after softening of the surface, thus accelerating aging of the surfaces of restorative resins. Material characteristics were assessed in terms of surface roughness, microhardness, ultimate tensile strength, solubility, and water sorption. Elution of methyl-methacrylate after specimen treatment was determined using HPLC. After 24h pre-incubation with sterile human saliva, the microbiological behavior of the materials was assessed using two models: Streptococcus mutans biofilm formation in a continuous-flow bioreactor simulating shear forces (30 ml/h) for 24 h, and artificial oral microcosm based on mixed plaque inoculum developed using the same setup for 24h. The viable biomass adhering to the specimens’ surfaces was measured using a tetrazolium dye-based test. Statistical analysis included verification of normality of distribution and homoscedasticity, then multi-way ANOVA and Student’s t-test (α= .05).
Results: Finishing protocol produced no significant differ- ences in surface roughness between tested materials. Ethanol treatment significantly reduced surface microhardness in both materials, but to a lesser extent on graphene-containing PMMA. No difference in ultimate tensile strength was found between materials. Graphene-containing PMMA showed sig- nificantly lower water sorption and solubility compared to conventional PMMA. After ethanol treatment, a significantly lower amount of leachates was identified for graphene- containing PMMA. Graphene addition significantly reduced biofilm formation compared to control in both microbiological models. Interestingly, specimen treatment produced the opposite (S. mutans model) or no effect (artificial oral microcosm) on biofilm formation.
Conclusions: Graphene-additioned PMMA is a promising material from both mechanical and microbiological point of view. Ethanol treatment influenced surface characteristics of the materials, leaving on graphene-additioned PMMA a sur- face more prone to bacterial colonization.
For additional informations: https://doi.org/10.1016/j.dental.2019.08.095
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