Monomer Leaching Research Articles

In vitro analysis of monomer leaching in modern dental materials: CAD milled, printed, traditional heat‐processed, and auto‐polymerizing denture base resins

AbstractPurposeDenture fabrication has shifted from traditional heat‐processed and auto‐polymerizing materials to computer‐aided design and computer‐aided manufacturing (CAD‐CAM) milled and printed materials. The monomer in traditional materials can induce an allergic reaction in some patients. With the rise in the edentulous population and increasing demand for the fabrication of dentures, these newer materials should be studied for monomer leaching. The purpose of this study was to evaluate the ratio of residual monomer in materials being used for denture bases: CAD‐milled polymethylmethacrylate (PMMA), printed denture base resin, heat‐processed PMMA, and auto‐polymerizing PMMA comparatively.Materials and MethodsMilled, printed, heat‐activated, and auto‐polymerizing denture base specimens (n = 3 for each group, each test run three times) were fabricated according to manufacturer recommendations. Specimens were first immersed in deuterated chloroform (CDCl3), a deuterated organic solvent, to evaluate monomer leaching and to observe physical properties of the materials. NMR spectroscopy was used to evaluate the dissolution of materials and residual monomer to crosslinked polymer ratios at 1, 4, and 9 days. A second group of specimens was then immersed in deuterium oxide (D2O) to evaluate if the residual monomers would leach out of the system. The solution was then analyzed using nuclear magnetic resonance (NMR) spectroscopy for 1 month. The deuterated forms of chloroform (CDCl3) and water (D2O) were used to enable sample characterization by NMR.ResultsWhile the heat‐processed, auto‐polymerizing, and milled specimens possessed residual monomers, no significant monomer leaching was noted in the printed specimen, while immersed in CDCl3. Similarly, the printed specimen was most resistant to dissolution, as compared to the rest; dissolution of the specimen is indicative of little to no cross‐linking. No detectable dissolution of monomer was seen when all specimens were immersed in D2O for up to 1 month.ConclusionsResidual monomers were not found in the printed denture material in this study in either CDCl3 or D2O, whereas CAD‐milled and traditionally processed denture bases still have residual monomers within their respective systems when immersed in organic solvent. None of the specimens tested leached monomers into D2O.

Nanoscale Simulation of Plastic Contaminants Migration in Packaging Materials and Potential Leaching into Model Food Fluids.

Polymers are the most commonly used packaging materials for nutrition and consumer products. The ever-growing concern over pollution and potential environmental contamination generated from single-use packaging materials has raised safety questions. Polymers used in these materials often contain impurities, including unreacted monomers and small oligomers. The characterization of transport properties, including diffusion and leaching of these molecules, is largely hampered by the long timescales involved in shelf life experiments. In this work, we employ atomistic molecular simulation techniques to explore the main mechanisms involved in the bulk and interfacial transport of monomer molecules from three polymers commonly employed as packaging materials: polyamide-6, polycarbonate, and poly(methyl methacrylate). Our simulations showed that both hopping and continuous diffusion play important roles in inbound monomer diffusion and that solvent-polymer compatibility significantly affects monomer leaching. These results provide rationalization for monomer leaching in model food formulations as well as bulky industry-relevant molecules. Through this molecular-scale characterization, we offer insights to aid in the design of polymer/consumer product interfaces with reduced risk of contamination and longer shelf life.

Composite Bone Cements with Enhanced Drug Elution.

Antibiotic-loaded bone cement (ALBC) has become an indispensable material in orthopedic surgery in recent decades, owing to the possibility of drugs delivery to the surgical site. It is applied for both infection prophylaxis (e.g., in primary joint arthroplasty) and infection treatment (e.g., in periprosthetic infection). However, the introduction of antibiotic to the polymer matrix diminishes the mechanical strength of the latter. Moreover, the majority of the loaded antibiotic remains embedded in polymer and does not participate in drug elution. Incorporation of the various additives to ALBC can help to overcome these issues. In this paper, four different natural micro/nanoscale materials (halloysite, nanocrystalline cellulose, micro- and nanofibrillated cellulose) were tested as additives to commercial Simplex P bone cement preloaded with vancomycin. The influence of all four materials on the polymerization process was comprehensively studied, including the investigation of the maximum temperature of polymerization, setting time, and monomer leaching. The introduction of the natural additives led to a considerable enhancement of drug elution and microhardness in the composite bone cements compared to ALBC. The best combination of the polymerization rate, monomer leaching, antibiotic release, and microhardness was observed for the sample containing nanofibrillated cellulose (NFC).

Effect of acidic saliva on monomer leaching and surface roughness of 3D-printed and milled denture-base materials

The study evaluated the effect of different acidic salivary pH values on monomer leaching and surface roughness of conventional and CAD/CAM processed (milled and 3D-printed) denture base materials. High-performance liquid chromatography was used to determine the quantity of residual methyl methacrylate monomer leaching after 30 days of immersion in acidic saliva. The surface roughness (Ra) before and after incubation was recorded using a non-contact optical profilometer. The monomer leaching and the surface roughness of the tested materials depended on the pH value of the saliva. The conventional denture framework material exhibited the highest and lowest leaching rates at pH=4.5 and pH=3.5, respectively, regardless of the treatment method. Among the CAD/CAM processed materials, the 3D-printed material showed the highest and lowest leaching at pH=5.5 and pH=3.5, respectively. Regardless of the pH, roughness after incubation was the lowest for conventional materials, and the highest for 3D printing.

A Martini 3 coarse-grain model for the simulation of the photopolymerizable organic phase in dental composites.

Light-hardening dental composites can be used in a large number of applications in restorative dentistry. They are based on photopolymerizable resins, which are highly relevant also in other industries like 3D printing. Much effort is therefore being put into developing and optimizing photopolymers. Currently used photopolymers still have limitations regarding mechanical properties, shrinkage and leaching of uncured monomers. These issues are strongly linked to the network structure of the polymer and are usually addressed using trial and error methods. Therefore, it is of interest to have a model for the network structure of such materials and to have a tool to facilitate scientific progress and the development of high-performance photopolymers. This work presents a coarse grain model of Bis-GMA/TEGDMA formulations and their corresponding networks, following the Martini 3 guidelines and using a simulated polymerization algorithm. The model proved to reproduce the densities and volumetric shrinkage values found in the literature well. Furthermore, it was possible to estimate the final double bond conversion of the polymer material. Martini's building block-like design makes it easy to extend the model to other monomers in the future.

In vitro evaluation of physicochemical properties of soft lining resins after incorporation of chlorhexidine

Statement of problemIncorporating chlorhexidine into soft lining materials has been suggested to reduce biofilm development on the material surface and treat denture stomatitis. However, evaluation of the physicochemical properties of this material is necessary. PurposeThe purpose of this in vitro study was to evaluate the physicochemical properties of resin-based denture soft lining materials modified with chlorhexidine diacetate (CDA). Material and methodsTwo soft lining resins were tested, one based on polymethyl methacrylate (PMMA) and the other on polyethyl methacrylate (PEMA), into which 0.5%, 1.0%, or 2.0% of CDA was incorporated; the control group had no CDA. The specimens were stored for 2 hours, 48 hours, 7, 14, 21, and 28 days and then analyzed for polymer crystallinity, Shore A hardness, degree of monomer conversion, residual monomer leaching, and CDA release. Data were analyzed by using a 3-way ANOVA and the Tukey HSD test (α=.05). ResultsThe polymer crystallinity of PEMA and PMMA did not change after CDA incorporation. Shore A hardness increased over time, but not for any CDA concentrations tested after 28 days (P>.05). Considering the degree of conversion, PMMA-based resin showed no statistically significant difference (P>.05). However, PEMA-based resin showed a significant decrease (P<.05), which was reflected in a significant increase in residual monomer leaching from PEMA-based resin with the incorporation of 0.5% and 1.0% CDA (P<.05), mainly in the first 48 hours. PMMA-based resin showed no change in monomer leaching (P>.05). For both resins, the CDA release kinetics were related to monomer leaching; for PEMA-based resin, the values were significantly higher in the first 48 hours (P<.05), and for PMMA-based resin, the values were more sustained up to the last day of analysis. ConclusionsThe incorporation of CDA did not affect the physicochemical properties of soft resins. The properties of PMMA were better than those of PEMA.

Safety Considerations for Thermoplastic-Type Appliances Used as Orthodontic Aligners or Retainers. A Systematic Review and Meta-Analysis of Clinical and In-Vitro Research.

Use of thermoplastic material in orthodontics, either as aligner or as retainer appliances, is common practice and is likely to increase in the years to come. However, no systematic assessment on safety considerations of these adjuncts has been implemented up to date. The aim of this systematic review was to collectively appraise the existing evidence from both clinical and laboratory studies, on whether these appliances are associated with any estrogenic/cytotoxic effects or bisphenol-A (BPA) and monomer leaching. Eight electronic databases were searched with no limits in December 22, 2019, for published and unpublished research. Eligibility criteria comprised of studies of any design, describing use of any type of thermoplastic aligner. Study selection, data extraction and risk of bias (RoB) assessment was done independently, either in duplicate or confirmed by a second reviewer. Random effects meta-analyses of weighted mean differences (WMD) with associated 95% Confidence Intervals (CIs) were planned. Quality of the evidence was evaluated with Grading of Recommendations Assessment, Development and Evaluation (GRADE). A total of 58 articles were initially identified, while 5 were included in qualitative synthesis and 2 of those contributed to the quantitative syntheses. Four studies were in-vitro, while one was a randomized controlled trial; all assessed some type of orthodontic aligner or retainer, either as-received or retrieved. Risk of bias recordings ranged between unclear and high for all studies. Proliferation induction capacity of thermoplastic appliances’ eluents on MCF-7 cells failed to be confirmed compared to beta-estradiol (2 studies: 5% v/v, WMD: −182.08; 95% CI: −198.83, −165.33; p-value < 0.001; and 20% v/v, WMD: −184.53; 95% CI: −206.17, −162.88; p-value < 0.001). No cytotoxic activity was detected as well. In addition, although evidence from in-vitro studies was indicative of no traceable detection of BPA or other monomers, the findings from a single clinical trial were allied to increased levels of BPA in whole stimulated saliva, after up to 30 days of thermoplastic retainer usage, compared to standard Hawley retainer. The quality of the evidence overall was low to medium. Current data from in-vitro research are indicative of an absence of an estrogenic or cytotoxic effect of thermoplastic aligners or retainers. Regarding BPA or monomer release, evidence from clinical and laboratory studies appear inconsistent.

Short-term and long-term release of monomers from newly developed resin-modified ceramics and composite resin CAD-CAM blocks

Statement of problemMonomer leaching from restorations may affect the oral mucosa and general health; however, information on monomer leaching from chairside computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials is lacking. PurposeThe purpose of this in vitro study was to investigate the leaching of monomers from newly introduced resin-modified ceramics and composite resin CAD-CAM blocks that were immersed in water and ethanol for short-term and long-term incubation periods. Material and methodsTen square-shaped specimens of 5 newly introduced CAD-CAM blocks were suspended by means of a silk thread in distilled water and in 75% ethanol. After 1 day, 7 days, 30 days, and 60 days, the eluates bisphenol A (BPA), urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEGDMA), N, N-dimethylacrylamide (DMA), bisphenol A-glycidyl dimethacrylate (Bis-GMA), and bisphenol A ethoxylate dimethacrylate (Bis-EMA) were analyzed by means of high-performance liquid chromatography (HPLC). Additional specimens of each material, before and after immersion in the solutions, were investigated by scanning electron microscopy, and elemental analysis was performed by energy-dispersive X-ray spectrometry. ResultsTEGDMA and UDMA were the main monomers eluted from all the materials tested. A pattern of declining release was detected for all the monomers. Bisphenol-A was not released by any of the investigated ceramic-composite or composite resin blocks either in water or ethanol. ConclusionsCAD-CAM blocks release less monomer when they are immersed in aqueous solutions in the short-term and long-term periods than conventional resin composite materials. The amount of monomer release declined until no monomer could be detected.

Metalloproteinases and their role in the degradation of bonding systems. Part 2

The stability of the hybrid layer is crucial for ensuring the durability of fillings made of composite materials. Factors which weaken the bond strength are related to, among others, the presence of bacteria and their enzymes in the structure of the bacterial biofilm. Chronic damage the hybrid layer is also a result of hydrolysis and leaching of adhesive monomers which infiltrated the demineralised dentin matrix. Nanoleakage is also among the factors contributing to degradation. Many studies examine the effect of endogenous proteases on the degradation of the hybrid layer. Endogenous collagenolytic enzymes: metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the degradation of the collagen matrix in the hybrid layer. Inhibition of endogenous proteases is therefore necessary to slow the degradation of fillings. The enzyme activity in dentine and in the hybrid layer can be regulated by endo- and exogenous inhibitors. The paper is a review of the available literature published in the PubMed medical database, as well as in Polish dental journals in the years 2002-2017. Its aim is to assess the role of metalloproteinases and cysteine cathepsins in the degradation of the hybrid layer and to review the compounds with inhibitory properties in relation to these enzyme groups.

Difunctional vinyl sulfonate esters for the fabrication of tough methacrylate-based photopolymer networks

Chain transfer reagents serve as a valuable tool for the modification of methacrylate-based photopolymer networks. Employment of such chemistry enables easy tuning of mechanical and thermomechanical network properties, thus potentially widens the field of application for such crosslinked polymer networks. Thiols are the most prominent class of chain transfer reagents and possess a great number of favorable characteristics (e.g., high conversion, reduced shrinkage stress, or high toughness, meaning the combination of high tensile strength and impact resistance). Mostly, thiols with higher functionality are used for network formation as monomer leaching and thinning effects are crucial drawbacks of monofunctional additives. Addition fragmentation chain transfer (AFCT) reagents (e.g., vinyl sulfonate esters) have been recently introduced as powerful network regulators for methacrylate-based photopolymerization. After successful synthesis of a difunctional vinyl sulfonate ester the photoreactivity in methacrylate-based systems was compared to an equivalent thiol-ene system. Through the introduction of a difunctional vinyl sulfonate ester-derivative, homogeneous photopolymer networks with high conversions, reduced shrinkage stress, tunable crosslink density and thermomechanical properties were fabricated. The final materials exhibit high hardness, tensile strength and gel content as well as improved impact resistance.

HPLC study of the inhibiting effect of phosphate and bicarbonate buffers on the leaching pattern of dental resin composites

ABSTRACTA high-performance liquid chromatographic method was applied to evaluate the effect of bicarbonate (NaHCO3) and phosphate (NaH2PO4, Na2HPO4) buffers on monomer leachability of dental resin composites. Evetric was the restorative resin composite that was investigated in current study. Forty disk-shaped resin composite specimens (n = 40) were immersed by means of a silk string in the following solutions: Distilled water (A), phosphate buffer (B), bicarbonate buffer (C), artificial saliva (D). After seven (7) and fourteen (14) days, the eluates were analyzed by means of High Performance Liquid Chromatography (HPLC). Subsequently, new specimens were fabricated and immersed in fresh solutions in which methanol 12% (v/v) was added. After seven and fourteen days of storage, the leaching of monomers was examined by means of HPLC, which was proved to be an effective tool to buffers demonstrate the inhibiting effect of phosphate and bicarbonate ions on the leaching pattern of dental resin composites.

Physical-chemical properties of dental composites and adhesives containing silane-modified SBA-15.

The aim of this study was to synthesize and characterize mesoporous materials SBA-15 and SBA-15 modified with 3-(methacryloxy)-propyl-trimethoxysilane (MPS) to be used as inorganic filler in restorative dental composites and adhesives, and evaluate the main physical-chemical properties of the resulting material. The SBA-15 and SBA-15/MPS were characterized by FTIR, BET and X-Ray and combined with TEGDMA, bis-GMA and commercial spherical silica to produce dental composites. Afterwards, the mesoporous materials were combined with TEGDMA, bis-GMA and HEMA to make adhesives. To compare the results, composites and adhesives containing only commercial spherical silica were investigated. Some physical-chemical properties such as degree of conversion (DC), flexural strength (FS) and modulus (FM), water sorption and solubility (Wsp and Wsl), specific area (BET), and the leachable components were evaluated. The SBA-15/MPS can be used to prepare dental restorative materials, with some foreseeable advantages compared with pure SBA-15 dental materials and with improved properties compared with commercial spherical silica dental materials. An important improvement was that the dental materials based on modified SBA-15 presented a reduction of approximately 60% in leaching of unreacted monomers extracted by solvent compared to the control group.

The adverse effects of virgin microplastics on the fertilization and larval development of sea urchins

Over the last decade, laboratory experiments have revealed a wide range of adverse effects in marine organisms following exposure to microplastics. This study investigated the working hypothesis that the observed effects of two types of virgin micro polymers ((polystyrene (PS) and high density polyethylene (HDPE)) might be, at least in part, due to the leaching of co-contaminants. For this purpose, the toxicity of these two polymeric materials and their leachates was tested on gametes and zygotes of the sea urchin Paracentrotus lividus following validated procedures. Zygotes were exposed for 48 hours to virgin and aged microspheres and leachates of fluorescent PS (10^3, 10^4 and 10^5 particles/mL) and agranular HDPE fluff (0.005, 0.5 and 5 g/L). Additionally, sea urchin eggs were exposed for 10 minutes to virgin fluorescent PS microspheres (10^3, 10^4 and 10^5 particles/mL). After exposure, the fertilization rate and percentage of larval abnormalities as well as larval growth were determined and compared to control groups. Overall, toxic effects on embryonic development and larval growth of the sea urchin were found for all treatments (untreated and weathered particles and leachates) with both polymeric materials. Furthermore, the highest toxicity (% abnormalities and reduction of the larval growth > 50%) was found after exposure to the lowest concentrations of leachate solutions for both types of polymeric materials. Microplastic ingestion was observed in the gastric cavity of the larvae in a dose- dependent manner, but not in a toxicity-dependent manner. Furthermore, eggs pre-exposed to concentrations of PS microspheres (10^3, 10^4 and 10^5 particles/mL) showed a toxic effect on the fertilization rate and on subsequent larval development as well as growth in a dose-dependent manner. These findings demonstrate that virgin microplastics are toxic to sea urchins through the leaching of chemicals, e.g., additives, residual monomers and other co-contaminants, which has been confirmed by chemical analysis elsewhere. The results of this study highlight the necessity to wash or weather microplastics before they are used in experimental laboratory studies to allow a more realistic extrapolation of the results to field conditions.

Plastic and Human Health: A Micro Issue?

Microplastics are a pollutant of environmental concern. Their presence in food destined for human consumption and in air samples has been reported. Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown. The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research. Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined. Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards. If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response. Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed environmental pollutants. Chronic exposure is anticipated to be of greater concern due to the accumulative effect that could occur. This is expected to be dose-dependent, and a robust evidence-base of exposure levels is currently lacking. Although there is potential for microplastics to impact human health, assessing current exposure levels and burdens is key. This information will guide future research into the potential mechanisms of toxicity and hence therein possible health effects.

Thiol-ene-epoxy thermoset for low-temperature bonding to biofunctionalized microarray surfaces.

One way to improve the sensitivity and throughput of miniaturized biomolecular assays is to integrate microfluidics to enhance the transport efficiency of biomolecules to the reaction sites. Such microfluidic integration requires bonding of a prefabricated microfluidic gasket to an assay surface without destroying its biological activity. In this paper we address the largely unmet challenge to accomplish a proper seal between a microfluidic gasket and a protein surface, with maintained biological activity and without contaminating the surface or blocking the microfluidic channels. We introduce a novel dual cure polymer resin for the formation of microfluidic gaskets that can be room-temperature bonded to a range of substrates using only UVA light. This polymer is the first polymer that features over a month of shelf life between the structure formation and the bonding, moreover the fully cured polymer gaskets feature the following set of properties suitable for microfluidics: high stiffness, which prevents microfluidic channel collapse during handling; very limited absorption of biomolecules; and no significant leaching of uncured monomers. We describe the novel polymer resin and its characteristics, study through FT-IR, and demonstrate its use as microfluidic well-arrays bonded onto protein array slides at room temperature followed by multiplexed immunoassays. The results confirm maintained biological activity and show high repeatability between protein arrays. This new approach for integrating microfluidic gaskets to biofunctionalised surfaces has the potential to improve sample throughput and decrease manufacturing costs for miniaturized biomolecular systems.

Novel urethane-based polymer for dental applications with decreased monomer leaching

The aim of this study was to synthesize and characterize new multifunctional-urethane-methacrylate monomers to be used as the organic matrix in restorative dental composites, and evaluate the main physical-chemical properties of the resulting material. Bis-GMA (bisphenol-A-diglycidylmethacrylate) and GDMA (glycerol dimethacrylate) were modified by reacting the hydroxyl groups with isocyanate groups of urethane-methacrylate precursors to result in the new monomeric systems U-(bis-GMA)-Mod and U-(GDMA)-Mod, U=Urethane and Mod=Modified. The modifications were characterized by FTIR and 1H NMR. The final monomeric synthesized system was used to prepare dental resins and composites. The physical-chemical properties were evaluated and compared with those of bis-GMA composites with varying filler contents or unfilled resins. U-(bis-GMA)-Mod and U-(GDMA)-Mod can be used to prepare dental restorative composites, with some foreseeable advantages compared with bis-GMA composites. One significant advantage is that these composites have the potential to be less toxic, once they presented a reduction of 50% in leaching of unreacted monomers extracted by solvent.

Residual monomer release from orthodontic adhesives cured with different light sources

Introduction: The aim of this study was to evaluate the residual monomer release from orthodontic adhesives cured with light-emitting diode (LED) and halogen light sources.Methods: Seven hundred and twenty stainless steel brackets were divided into 3 groups according to the adhesive system used (Transbond XT light-cure adhesive [TXT], Transbond LR capsule [LR], and Light Bond light-cure adhesive paste [LB]), and each group was divided into 2 subgroups according to light-curing procedure (LED or halogen). Brackets were bonded with adhesives onto tooth buccal surfaces and polymerized. Each specimen contained 24 brackets that simulated the oral environment (n = 5). The specimens were immersed in a 75% ethanol/water solution at 37 °C for 10 min, 1 h, 1 d, 7 d, 14 d, and 30 d, respectively. Eluted monomers (Bis-GMA, UDMA, and TEGDMA) were detected using HPLC.Results: There was residual monomer release at all time periods, and the highest amount of release was observed cumulatively on the 30th day. The cumulative Bis-GMA released from adhesives was not different (p > 0.05). The cumulative TEGDMA released from adhesives was statistically different (p < 0.05). There was no statistical difference between QTH and LED light-curing units for each adhesive (p > 0.05).Conclusions: The release of residual monomers stays at a high level for a long time after polymerization. The total leaching of residual monomers from the Light Bond light-cure sealant resin plus Light Bond light-cure adhesive paste was higher than that of other materials for both curing units. Different curing units (LED or QTH) did not affect the monomer release from the orthodontic adhesives.

Degree of conversion and leached monomers of urethane dimethacrylate-hydroxypropyl methacrylate-based dental resin systems.

The degree of conversion (DC) and monomer leaching of three experimental urethane dimethacrylate (UEDMA)-hydroxypropyl methacrylate (HPMA)-based resin systems were studied. Three experimental resins (E1: 70.6 wt% UEDMA + 27.4 wt% HPMA, E2: 80.6 wt% UEDMA + 17.4 wt% HPMA, E3: 90.6 wt% UEDMA + 7.4 wt% HPMA) and one control resin [C: 70.6 wt% bis-phenol A glycidyl methacrylate (bis-GMA) + 27.4 wt% methyl methacrylate (MMA)] were prepared. For the DC test, cylindrical specimens [1.5 mm (h) × 6 mm (d)] were scanned with an ATR-FTIR instrument before and after light-curing (n = 5). For the monomer leaching test, block-shaped specimens [5.67 mm (l) × 2.00 mm (w) × 2.00 mm (h)] were light-cured (n = 6), stored in a 75% ethanol:water solution for 3 days, and then analyzed with HPLC. The UEDMA-HPMA-based experimental groups showed higher DC (62-78%) than the bis-GMA-MMA-based control group (58-66%), and the DC decreased as the UEDMA content increased (P < 0.05). Amongst the four groups, E3 exhibited the lowest leaching of both mono methacrylate (0.1% HPMA) and dimethacrylate (<0.043% UEDMA) monomers after 30 or 40 s of curing. The UEDMA-HPMA-based resins, therefore, exhibited higher DC and less monomer leaching compared to the bis-GMA-MMA-based resin. (J Oral Sci 58, 15-22, 2016).

Monomer leaching and degree of conversion of bioactive dental composites

Monomer leaching and degree of conversion of bioactive dental composites

Are Use Of Orthodontic Adhesives Detrimental To Health? An Overview.

nbsp nbsp nbsp nbsp nbsp Composite resins play an integral role in Orthodontic bonding of brackets to the teeth. Recently concerns have been raised regarding the cytotoxic and estrogenic effect of intra-orally placed resins. It has also been cited that these resins can cause loss of male fertility as well as have mutagenic and gingival inflammatory effects .It is yet to be ascertained whether the minute amount of monomers that are leached from intra oral resins can really contribute to all these effects. This review aims to evaluate the various detrimental effects of leached monomers in the mouth as well as to throw light on the threshold level for these monomers in the human body gives us a perspective on whether we should be alarmed about its reported toxic implications and gives suggestions on how monomer leaching can be minimized.