Performance Assessment of Three Similar Dental Restorative Composite Materials via Raman Spectroscopy Supported by Complementary Methods Such as Hardness and Density Measurements.

(1) Background: A widespread problem in oral health is cavities produced by cariogenic bacteria that consume fermentable carbohydrates and lower pH to 5.5-6.5, thus extracting Ca2+ and phosphate ions (PO43-) from teeth. Dental restorative materials based on polymers are used to fill the gaps in damaged teeth, but their properties are different from those of dental enamel. Therefore, a question is raised about the similarity between dental composites and natural teeth in terms of density and hardness. (2) Methods: We have used Raman spectroscopy and density and microhardness measurements to compare physical characteristics of several restorative dental composites at different polymerization intervals. (3) Results: XRVHerculite®, Optishade®, and VertiseFlow® showed the very different characteristics of the physical properties following four polymerization intervals. Of the three composites, OptiShade showed the highest polymerization rate. (4) Conclusions: Only fully polymerized composites can be used in teeth restoring, because incomplete polymerization would result in cracks, pitting, and lead finally to failure.

Raman Spectroscopy as Spectral Tool for Assessing the Degree of Conversion after Curing of Two Resin-Based Materials Used in Restorative Dentistry.

(1) Background: The treatment of dental cavities and restoration of tooth shape requires specialized materials with specific clinical properties, including being easy to model, light-cured, having a natural color, reduced shrinkage, a hardness similar to hydroxyapatite, and no leakage. The dimensional stability of resin composite materials is affected by polymerization shrinkage, degree of conversion (number of π carbon bonds converted into σ ones), thermal contraction and expansion, and interactions with an aqueous environment. (2) Methods: The materials used in our investigation were two composite resins with similar polymer matrices, but different filler (micro/nano filler). To evaluate the properties of samples, we employed the pycnometer technique (pycnometer from Paul Marienfeld Gmbh, Lauda-Königshofen, Germany), RAMAN spectroscopy technique (MiniRam Equipment from B&W Tek Inc., Plainsboro Township, NJ, USA; 785 nm laser source), SEM and EDX (FEI Inspect S.). (3) Results: The size of the filler plays an important role in the polymerization: for the pycnometric results, the larger particle filler (Sample 1) seems to undergo a rapid polymerization during the 45 s curing, while the nanoparticle filer (Sample 2) needs additional curing time to fully polymerize. This is related to a much larger porosity, as proved by SEM images. The lower degree of conversion, as obtained by Raman spectroscopy, in the same geometry means that the same volume is probed for both samples, but Sample 1 is more porous, which means less amount of polymer is probed for Sample 1. (4) Conclusions: For the two composites, we obtained a degree of conversion of 59% for Sample 1 and 93% for Sample 2, after 45 s of curing.

Experiential learning for adolescents - results from a 2-year school-based oral health educational program.

BACKGROUND: For oral health promotion, teenagers represent an important target group, given that appropriate personal oral hygiene and dietary behaviors are established during this period of life. Experiential learning is an educational approach where learning comes through experience. THE AIM: of the Erasmus+ project "Youth Community-Based Oral Health Learning Model" was to assess the influence of a school-based experiential education program on oral health status, knowledge and behavior among a group of schoolchildren in Bucharest. METHODS: This longitudinal interventional study started in 2015 and enrolled 120 adolescents from three public schools. At baseline, all subjects were clinically examined and received a questionnaire. They were split into two groups: the test group received three experiential lessons and control group benefited from a demonstration of tooth brushing technique. RESULTS: were presented for the test group, 76 schoolchildren, divided in two age groups: 13-14 years and 15-16 years. More children from the test group adopted twice-daily tooth brushing compared to the control group. The level of knowledge was good, but the role of a noncariogenic diet must be emphasized. CONCLUSIONS: The oral health program had positive effects on oral health knowledge and behavior among adolescents. The present study indicated that intervention using experiential learning involving dental students was effective in increasing oral health attitudes and behavior among adolescents from 13-16 years of age included in the study.