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

Abstract

(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.

Periodontal Disease Monitoring by Raman Spectroscopy of Phosphates: New Insights into Pyrophosphate Activity

“…Differences in peak intensity on raw spectra reflect the differences in the quantities of the chemical components for each investigated specimen. Sensitive qualitative/quantitative information may be obtained according to the Raman spectra shape, such as fluorescence by using raw data (no flat line subtraction and without smoothing) [ 5 , 15 , 17 , 18 ].…”

“…In the present study, we attempted to carry out an in vivo characterization of mineralization processes by Raman spectroscopy in patients with or without periodontitis. By doing so, we try to analyze the mineralization products, with an emphasis on pyrophosphate, and to provide some insight into the related mechanism [ 14 , 15 ]. Our attempt is another step toward developing and bringing the Raman spectroscopy method to the clinics as the end or final users.…”

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

“…Our group has been investigating the compatibility between several commercially available dental restorative materials and natural enamel [ 20 , 21 , 22 , 23 , 24 , 25 ]. In this paper, we aim to evaluate the physicochemical properties of three commercially available and widely used dental materials and rank them according to those properties.…”

Identification of Uric Acid Crystals Accumulation in Human and Animal Tissues Using Combined Morphological and Raman Spectroscopy Analysis

“…Raman spectroscopy is a nondestructive and effective tool that has been applied successfully to various fields such as: medicine [ 19 , 20 , 21 , 22 , 23 ], dental research [ 24 , 25 , 26 ], biology [ 27 ], food safety [ 28 ], chemistry [ 29 ], pharmacy [ 30 ], etc. Material identification and its structural characterization are complex, since Raman scattering acts at various levels, from surface to the depth of the samples.…”