https://www.endoexperience.com/documents/PIIS0099239909008978.pdf

Critical Review on Methacrylate Resin–based Root Canal Sealers

Eluted substances from unpolymerized and polymerized dental restorative materials and their Nernst partition coefficient.

The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-aenial Anterior® - Ge, (GC Europe N.V., Leuven, Belgium), Charisma® - Ch (Heraeus Kulzer, Berkshire, UK). The physio-chemical properties were studied, like the degree of conversion and the residual monomers in cured samples using FTIR-ATR (attenuated total reflectance) and HPLC-UV (ultraviolet detection), as well as the evaluation of the mechanical properties of the materials. The null hypothesis was that there would be no differences between experimental and commercial resin composites regarding the evaluated parameters. Statistical analysis revealed that water and saliva storage induced significant modifications of all mechanical parameters after three months for all tested materials, except for a few comparisons for each type of material. Storage medium seemed not to alter the values of mechanical parameters in comparison with the initial ones for: diametral tensile strength (DTS-saliva for Ge and PM, compressive strength (CS)-water for Ch, DTS-water and Young's modulus YM-saliva for P14M and YM-water/ saliva for P2S (p > 0.05). Two of the experimental materials showed less than 1% residual monomers, which sustains good polymerization efficiency. Experimental resin composites have good mechanical properties, which makes them recommendable for the successful use in load-bearing surfaces of posterior teeth.

https://www.mdpi.com/1996-1944/12/13/2109/pdf

Evaluation of the Degree of Conversion, Residual Monomers and Mechanical Properties of Some Light-Cured Dental Resin Composites.

Monomer elution from nanohybrid and ormocer-based composites cured with different light sources.

The degree of conversion (DC) and the released bisphenol A diglycidyl ether dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers of bulk-fill composites compared to that of conventional flowable ones were assessed using micro-Raman spectroscopy and high performance liquid chromatography (HPLC). Four millimeter-thick samples were prepared from SureFil SDR Flow (SDR), X-tra Base (XB), Filtek Bulk Fill (FBF) and two and four millimeter samples from Filtek Ultimate Flow (FUF). They were measured with micro-Raman spectroscopy to determine the DC% of the top and the bottom surfaces. The amount of released monomers in 75% ethanol extraction media was measured with HPLC. The differences between the top and bottom DC% were significant for each material. The mean DC values were in the following order for the bottom surfaces: SDR_4mm_20s > FUF_2mm_20s > XB_4mm_20s > FBF_4mm_20s > XB_4mm_10s > FBF_4mm_10s > FUF_4mm_20s. The highest rate in the amount of released BisGMA and TEGDMA was found from the 4 mm-thick conventional flowable FUF. Among bulk-fills, FBF showed a twenty times higher amount of eluted UDMA and twice more BisGMA; meanwhile, SDR released a significantly higher amount of TEGDMA. SDR bulk-fill showed significantly higher DC%; meanwhile XB, FBF did not reach the same level DC, as that of the 2 mm-thick conventional composite at the bottom surface. Conventional flowable composites showed a higher rate of monomer elution compared to the bulk-fills, except FBF, which showed a high amount of UDMA release.

https://www.mdpi.com/1422-0067/17/5/732/pdf

Degree of Conversion and BisGMA, TEGDMA, UDMA Elution from Flowable Bulk Fill Composites

High-performance liquid chromatographic determination of unreacted monomers and other residues contained in dental composites

The purpose of this study was to investigate the amount of residual monomer in a composite resin after light-curing with different sources, light intensities and spectra of radiation. The resin specimens (4 mm in diameter; 2 mm thick) (n=5) were inserted in Plexglass matrixes and light-cured with a halogen lamp, LED and PAC units for 40, 40 and 5 s, respectively. The polymerized specimens were ground and 25 mg of each specimen were immersed in 8 mL 96% ethanol for 24 h to extract the residual monomer. The amount of residual monomer was determined by the standard straight line method. The light spectrum of the different LCUs was shot and processed through researches of the absorbation of the standard solutions at a level of l= 275 nm and their extracts. Data were analyzed statistically by variational dispersion analysis and Tukey-Kramer test at 5% significance level. It was observed that, the halogen lamp produced the smallest amount of monomer under sufficient light intensity. The spectrum of light radiation of PAC was within the limits of 450- 490 nm and was of extremely high intensity. This imposes the use of short-limited light impulses, but also might lead to deterioration quality of polymerization. The LED unit had the best spectral radiation. An increase of light intensity was proved necessary.

/pdf/residual-monomer-in-a-composite-resin-after-light-curing-ypinckc9jl.pdf

Residual monomer in a composite resin after light-curing with different sources, light intensities and spectra of radiation

Modern endodontic surgery is microsurgical. The microscope, endoscope, ultrasonic tools, microinstruments allow much less trauma. Flaps reflection is less invasive, ostectomy and osteotomy is much smaller which improves healing and treatment outcome. Root resection is as big as possible and as much as needed to preserve the stability of teeth. Performing surgery without thorough knowledge of new advancements and concepts is below the standard of practice.

Periapical Surgery. Review. Classic vs Modern Concepts

Dental fluorosis changes the colour and/or structure of enamel, leading to an unaesthetic appearance. One of the main goals in the treatment is aesthetic improvement of the affected teeth. Two clinical cases of patients with white spot fluorosis lesions on frontal teeth are presented. All treated teeth are infiltrated with low-viscous light-curing resin (ICON, DMG). A significant improvement in the aesthetic appearance of all the treated tooth surfaces is visible immediately after resin infiltration, and in most of the teeth - a complete disappearance of the white spots. Resin infiltration is an alternative micro-invasive approach for treatment of white spot lesions of different origin. It allows a quick and natural recovery of the affected teeth.

Aesthetic Improvement of White Spot Fluorosis Lesions with Resin Infiltration.

The present work is focused on examining the effect of the structurally similar dental monomers bis-GA and bis-GMA on the expression of histo-blood group antigens (HBGAs) in comparison with fibroblast vitality and proliferation. The fibroblast cell line McCoy-Plovdiv was cultivated in a serum-free medium and was treated with both monomers. Cell vitality was measured by the crystal violet test. Mitotic index and cell morphology were assessed. An immunocytochemical technique was applied to follow the expression of proliferative antigens PCNA and Ki-67 and of HBGA. The expression level of HBGA was measured by an improved pixel selection algorithm with proprietary software. The lowest concentration of 2.5 μmol/L did not significantly affect morphology, vitality, or proliferation activity. Interestingly, the quantitative analysis revealed augmented expression of HBGA B at 2.5 μmol/L. The higher concentrations of the dental monomers reduced cell vitality and mitotic indices and altered proliferative antigen expression. Bis-GA proved to be more toxic than bis-GMA and caused more prominent alterations including greater enhancement of HBGA B expression. We present novel evidence for altered expression of proliferative antigens and enhanced expression of HBGA B in fibroblasts treated with dental monomers bis-GA and bis-GMA suggesting that these substances affect cell morphology, proliferative activity, and antigenic profile.

Ivan Filipov

Papers

High-performance liquid chromatographic determination of unreacted monomers and other residues contained in dental composites

Residual monomer in a composite resin after light-curing with different sources, light intensities and spectra of radiation

Periapical Surgery. Review. Classic vs Modern Concepts

Aesthetic Improvement of White Spot Fluorosis Lesions with Resin Infiltration.

Histo-blood group antigen expression and proliferative activity of fibroblasts treated with dental monomers.