Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites

Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites Madiana Magalhães Moreira, Ana Larissa da Silva, Rita de Cássia Sousa Pereira, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4648523/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 08 Oct, 2024 Read the published version in Clinical Oral Investigations → Version 1 posted 9 You are reading this latest preprint version Abstract Objectives To analyze the incorporation of cardanol trimethacrylate monomer (CTMA), derived from the cashew nut shell liquid, as a substitute for Bis-GMA on the physicochemical and mechanical properties of experimental resin composites. Materials and Methods The intermediary cardanol epoxy was synthesized via cardanol epoxidation, followed by synthesis of CTMA through methacrylic anhydride solvent-free esterification. Experimental resin composites were formulated with an organic matrix composed of Bis-GMA/TEGDMA (50/50 wt %) (control). CTMA was gradually added to replace different proportions of Bis-GMA: 10 wt % (CTMA-10), 20 wt % (CTMA-20), 40 wt % (CTMA-40), and 50 wt % (CTMA-50). The composites were characterized in terms of degree of conversion, water sorption and solubility, viscosity, thermogravimetric analysis, dynamic mechanical analysis, flexural strength and elastic modulus. Data were analyzed with one-way ANOVA and Tukey's post-hoc test (α = 0.05), except for water sorption data, which were analyzed by Kruskall-Wallis and Dunn’s method. Results CTMA-based and control composites did not show statistically significant differences regarding degree of conversion, flexural strength and elastic modulus. CTMA reduced the viscosity and solubility compared to Bis-GMA-based composite. The CTMA-40 and CTMA-50 exhibited significantly lower water sorption compared to the control. Also, acceptable thermal stability and viscoelastic properties were obtained for safe use in the oral cavity. Conclusions The incorporation of CTMA into composites resulted in similar chemical and mechanical properties when compared to Bis-GMA-based material, while reducing viscosity, water sorption and solubility. Clinical Relevance CTMA could be used as a trimethacrylate monomer replacing Bis-GMA in resin composites, thereby minimizing BPA exposure. Cardanol. Methacrylates. Composite resins. Physicochemical properties. Flexural strength. Dynamic mechanical property Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1 Introduction The structure and functional groups of the monomers employed in dental materials strongly influence polymer network formation and characteristics, such as mechanical properties, degree of conversion, crosslinking formation and viscosity [ 1 ]. Bisphenol A glycidyl methacrylate (Bis-GMA) is the most commonly monomer used in polymer matrix formulations due to its high molecular weight, low polymerization shrinkage and excellent mechanical properties [ 2 ]. However, its high viscosity, attributed to intermolecular hydrogen bond formation, demands the addition of low molecular weight monomers, such as hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) [ 2 ]. TEGDMA is widely used in resin composites to reduce viscosity and increase filler incorporation; however, it reduces mechanical properties and increases polymerization shrinkage and water sorption [ 3 ]. Moreover, Bis-GMA is a derivative of bisphenol A (BPA), a synthetic compound which mimics the estrogen hormone, being considered an endocrine disruptor that, even at low doses, may contribute to the pathogenesis of several diseases [ 4 ]. Exposure to BPA in the oral cavity has been explored, as this compound can be released by degradation of derivatives used in the formulation of resin-based materials, such as Bis-GMA [ 5 ]. Worryingly, the potential impact of this release on human health remains uncertain. In this constant search for improvements in biocompatibility, Bis-GMA free compounds have been widely researched, such as dimethacrylate monomers from bio-based material creosol [ 6 ], isosorbide-based monomer [ 7 ], and dendrimers [ 8 ]; as well as new resin-based systems, such as thiol-enes [ 9 ]. In order to improve long-term performance of dental materials, multimethacrylates have been investigated. Although some trimethacrylates exhibited mechanical properties comparable to the Bis-GMA composites, they resulted in a lower polymerization rate, higher viscosity, water sorption and solubility [ 10 , 11 ]. Contrariwise, Park et al. (2012) concluded that a trimethacrylate monomer added to dentin adhesives reduced viscosity and increased crosslink density and double bond conversion [ 12 ]. Among the natural and renewable sources that has been employed for the synthesis of new monomers for dental applications, the cashew nut shell liquid (CNSL) stands out [ 13 – 15 ], a biomass rich in phenolic lipids that represents approximately 25% of the cashew nut weight [ 16 ]. Technical CNSL is a byproduct of the cashew nut manufacturing industry, composed primarily of cardanol (67.8 to 94.6%) [ 16 ]. This monomer exhibits structural characteristics favorable for use in dental materials, such as long carbon chain and several reaction sites (CN, Fig. 1 ), suitable for the incorporation of functional groups. The use of monomers with long spacer carbon chain is favorable since they provide high hydrophobicity, resulting in lower water sorption, reduced polymer degradation, and greater hydrolytic stability to the polymer [ 17 ]. Moreover, the aromatic ring of cardanol contributes to relative stiffness and polymeric strength, while the alkorganicyl chain provides flexibility, reducing its viscosity and the subsequent requirement of considerable incorporation of low molecular weight monomers. Supported by these promising structural characteristics of the molecule, cardanol methacrylate epoxidized monomer was synthesized and employed in a resin-based desensitizer, achieving the greatest reduction in dentin permeability and most homogeneous and occluded surface among desensitizers tested, even after acid challenge [ 13 ]. Recently, cardanol was also functionalized with a methacrylate and the synthesized monomer reduced the adhesive resin solubility without interfering in polymerization [ 14 ] Therefore, cardanol highlights as a molecule with attractive structural features for the synthesis of new methacrylate monomers, bringing alternatives to improve the properties of dental materials with wide range of dental applications. The synthesis of a trimethacrylate from cardanol, as the major component of the CNSL and with promising physicochemical and structural properties, could generate hydrophobic resin-based materials with high mechanical strength, polymer crosslinking and hydrolytic stability, also reducing the use of BPA-derived monomers. The aim of this manuscript was to analyze the effect of incorporating cardanol trimethacrylate (CTMA) monomer derived from CNSL, as a substitute for Bis-GMA, on the physicochemical and mechanical properties of experimental resin composites. The hypotheses of the study are that the addition of CTMA in resin composites (1) does not jeopardize chemical properties (degree of conversion and thermal-degradation), (2) reduces the viscosity, water sorption and solubility, and (3) promotes mechanical properties similar to traditional Bis-GMA-based systems. 2 Material and methods 2.1 Reagents Cardanol was kindly supplied by Satya Chemicals (Eluru, India). Formic acid (85%), hydrogen peroxide (35%), ethyl acetate, sodium bicarbonate, and anhydrous sodium sulfate were used as received from LabSynth (São Paulo, Brazil). BHT (3,5-Di-tert-4-butylhydroxytoluene), and methacrylic anhydride were purchased from Sigma-Aldrich (St. Louis, USA) and used as received. Silica gel (63–200 µm; Sigma-Aldrich, St. Louis, USA) was employed in the chromatographic separations. 2.2 Synthesis of cardanol trimethacrylate (CTMA) The organic synthesis of the methacrylic monomer was performed according to the synthetic route illustrated in Fig. 1 , initially involving an epoxidation reaction of the unsaturated carbon chain of cardanol, followed by replacement of the phenolic hydroxyl and oxirane ring-opening to incorporate methacrylic groups. The intermediate product cardanol epoxy (CNE) was obtained, as performed by Pereira et al. [ 18 ] with modifications. The synthesis of CNE involved the epoxidation of the unsaturations of cardanol (CN) with performic acid formed in situ from the reaction between formic acid and hydrogen peroxide, catalyzed by Amberlite IR 120H, using the molar ratio of 1.0: 0.5: 3.0 (unsaturation: formic acid: hydrogen peroxide). In a round bottom flask (100 mL), 10 g of cardanol (56.8 mmol of unsaturation) was weighed followed by the addition of 1.26 mL of formic acid (28.4 mmol) and 2 g of Amberlite IR 120H (20 wt % of cardanol). The mixture was kept under magnetic stirring for 10 minutes. Then, using a burette, 16.3 mL of hydrogen peroxide (170.5 mmol) was added dropwise under constant stirring at room temperature. After that, the mixture was heated in a silicone bath at 65°C and continuously stirred for 4 hours to obtain CNE as a reddish-brown oil (90% yield). Cardanol trimethacrylate (CTMA) monomer was obtained by a simultaneously oxirane ring-opening and hydroxyl substitution esterification reaction of CNE with methacrylic anhydride in a molar ratio of 1:1, and 2.5 wt % of triphenylphosphine. Also, 0.01 wt % BHT was added to avoid spontaneous polymerization. CTMA synthesis was carried out under microwave irradiation (Milestone microwave reactor; StartSYNTH, Shelton, USA) operating with 2.45 GHz frequency and 800 W maximum power. The procedure begins by weighing 4 g of CNE (12.6 mmol) in a round bottom flask (25 mL), followed by the addition of 2.0 mL of methacrylic anhydride (12.6 mmol) and 0.1 g of triphenylphosphine (0.381 mmol). The flask was connected to a 50 cm Vigreux condenser and placed in the microwave cavity under constant magnetic stirring, programmed to ramp up from room temperature to 80 ºC within 2 minutes and maintain this temperature for 20 minutes. Subsequently, it was ramped up from 80 ºC to 120 ºC within 2 minutes and maintained for an additional 10 minutes. CTMA was obtained as a light-yellow oil with a yield of 87.4%. The progress of the reactions was monitored by thin layer chromatography. At the end of each reaction, mixture was cooled down to room temperature and vacuum filtered to remove the heterogeneous catalyst. The filtrate was transferred to a separation funnel (250 mL), neutralized with saturated sodium bicarbonate solution and extracted with ethyl acetate. Organic phase was collected, dried with anhydrous sodium sulfate, concentrated under reduced pressure and purified through a silica chromatography column to obtain the respective products. Products were kept in a fridge (4 ºC) and protected by aluminum foil to avoid spontaneous polymerization. 2.3 Monomer characterization CNE and CTMA were characterized by Fourier transform infrared spectroscopy (FT-IR) and 1 H and 13 C nuclear magnetic resonance (NMR) techniques. 2.3.1 Fourier transform infrared vibrational spectroscopy (FT-IR) FT-IR spectra were obtained in a Spectrum Frontier (Perkin-Elmer Corp., Norwalk, USA) equipped with zinc selenide (ZnSe) crystal to perform attenuated total reflectance (ATR) analysis. Samples of the isolated monomers were individually dispensed onto the crystal. The wavelength range of analyzes was 4000–550 cm − 1 with a resolution of 4 cm − 1 and 32 scans 2.3.2 Nuclear magnetic resonance (NMR) The 1 H NMR and 13 C NMR spectra were recorded on a nuclear spectrometer instrument (Avance DPX, Bruker, Rheinstetten, Germany) operating at 75 MHz for 13 C and 300 MHz for 1 H. Deuterated chloroform was used to solubilize samples at room temperature. 2.4 Experimental resin composite formulation Experimental resin was formulated with an organic matrix composed of 50 wt % bisphenol A glycidyl methacrylate (Bis-GMA) and 50 wt % triethylene glycol dimethacrylate (TEGDMA) (Control). CTMA was gradually added, replacing Bis-GMA: 10 wt % (CTMA-10), 20 wt % (CTMA-20), 40 wt % (CTMA-40), and 50 wt % (CTMA-50) as shown on Table 1 . Camphoroquinone (0.5 wt %) and ethyl 4-dimethylaminebenzoate (EDAB, 1 wt %) were used, respectively, as photoinitiator and co-initiator with respect to the total amount of monomers. Table 1 Organic matrix composition of the experimental resins Monomeric composition (wt %) Composites Bis-GMA a TEGDMA b CTMA c Control 50 50 0 CTMA-10 40 50 10 CTMA-20 30 50 20 CTMA-40 10 50 40 CTMA-50 0 50 50 a Bis-GMA: bisphenol A glycidyl methacrylate. b TEGDMA: triethyleneglycol dimethacrylate. c CTMA: cardanol trimethacrylate. The organic matrices of the resins were loaded with 65 wt% of silanated barium borosilicate glass (average particle size of 0,7 µm; Esstech Inc., Essington, USA) and were mechanically manipulated in an amalgamator (Ultramat S, SDI, Victoria, Australia). 2.5 Degree of conversion The polymerization of composite resins was evaluated using FT-IR with similar set-up described in characterization section. The unpolymerized composites (1mm height) were placed directly on the diamond ATR crystal and spectra were obtained. Disc-shaped specimens (n = 3) were prepared by filling a stainless-steel mold of 6 mm in diameter and 1 mm thickness (Odeme Dental Research, Luzerna, Brazil) with unpolymerized composites, which were covered by a polyester strip and light-cured for 40 seconds on each side with LED curing unit with 1200mW/cm² irradiance (Valo, Ultradent, South Jordan, USA). Polymerized specimens were evaluated 24 hours after dry storage. The conversion of the methacrylic double bond was monitored by calculating the ratio between the bands 1637 cm − 1 (aliphatic C = C double bond) / 1608 cm − 1 (aromatic C = C double bond as internal reference) from cured and uncured composite resins. The analysis was performed in triplicate [ 14 ]. 2.6 Water sorption and solubility evaluation Disk-shaped specimens (n = 10) were prepared according to ISO 4049 − 2009 [ 19 ], except for the size of specimens, by using a stainless-steel mold of 6 mm in diameter and 1 mm thickness. This matrix was filled with unpolymerized composites, which were covered by a polyester strip, light-cured for 40 seconds on each side with LED (Valo) and stored in a dissector with silica gel at 37°C. To obtain m1, disks were weighed at each 24 hours in precision balance (Marte Científica AUW220D, São Paulo, Brazil) until a constant dry mass was obtained (variation less than 0.2 mg in three weight measures). Next, the specimens were stored in eppendorfs with 1.5 mL of distilled water at 37°C. After 7 days of immersion, they were washed, gently wiped with absorbent paper and weighed in the precision balance to measure m2. Subsequently, the specimens were dried in the desiccator and weighed daily until a final constant mass was obtained (m3). The volume (V) of the specimens (mm 3 ) was calculated by measuring the thickness and diameter with a digital caliper (± 0.01 mm). Water sorption (WS) and solubility (SL) were calculated (µg/mm 3 ) according to the formulas below. $$WS=\frac{m2-m3}{V} SL=\frac{m1-m3}{V}$$ 2.7 Viscosity measurements The organic matrix of the experimental resins had their viscosities measurements carried out on a rotational rheometer equipped with a 50 mm diameter cone-plate geometry (RST-CPS, Brookfield, Lorch, Germany). For each measurement 1 mL of resin formulation was applied on the lower plate of the rheometer for 5 s before the upper plate was moved downward to adjust the gap to a thickness of 0.045 mm. Each measurement was repeated three times, with a recovery period between each run, and the following parameters were kept constant: shear rate from 1 to 1000 s − 1 at 20°C for 120 s [ 20 ]. 2.8 Thermogravimetric Analysis (TGA) The thermal behavior of composites was determined as a function of the increasing temperature using a TGA/SDTA851e thermogravimetric analyzer (Mettler Toledo, Schwerzenbach, Switzerland), in a temperature range from 30 to 800 ◦C at a heating rate of 10 º C/min, under nitrogen atmosphere. Samples (n = 3; 10 mg of each organic matrix of the resins) were light-cured for 40 seconds with LED curing unit (Valo). The thermal stability and degradation characteristics of each group were predicted according to the temperatures at which decomposition (weight changes) of the polymers occurs [ 18 ]. 2.9 Dynamic mechanical analysis (DMA) The viscoelastic properties of the resins organic matrix were characterized using a DMA 1 equipment (Mettler Toledo, New Castle, USA) with the following parameters: single-cantilever clamp at a frequency of 1 Hz, amplitude of 10 µm, in a temperature range from 30 to 200 ◦C and at a heating rate of 5 º C/min. The composites were dispensed in a stainless-steel mold (25 mm length, 2 mm width and, 2 mm thickness; Odeme Dental Research) and light-cured (four times of 20 s on each side) using the overlapping method with LED curing unit (Valo). After 24 hours of dry storage, the polymerized samples were subjected to dynamic mechanical analysis. Three specimens of each group were measured (storage modulus and tan δ) and the results were averaged [ 21 ]. 2.10 Flexural strength and elastic modulus The flexural strength was evaluated according to ISO 4049 − 2009 [ 19 ], except for the dimensions of the specimens. Bar-shaped specimens (n = 6) were obtained by filling a stainless-steel mold (10 mm length, 2 mm width and, 2 mm thickness; Odeme Dental Research) with the experimental composites, which were covered by a polyester strip and light-cured (two times of 20 s on each side) using the overlapping method with LED curing unit (Valo). The polymerized specimens were kept in distilled water at 37 º C for 24 h and then subjected to the three-point bending test performed with a universal testing machine (EMIC 23-2S; Instron, São José dos Pinhais, Brazil), at a crosshead speed of 1.00 mm/min until fracture. The flexural strength (σ) and elastic modulus (E) were calculated using the following formulas: $$\sigma =\frac{3Fl}{{2bh}^{2}} E= \frac{{F}_{1 }{l}^{3}}{4b{h}^{3}d}$$ Where: F = maximum load (N) exerted on the specimen at the point fracture; l = distance between the supports (7 mm); b = width (mm) of the specimen measured immediately prior to testing; h = height (mm) of the specimen measured immediately prior to testing; F 1 = load (N) recorded when the deformation stops being directly proportional to the force registered in the graph; d = deflection of the specimen corresponding to the load F 1 [ 3 ]. 2.11 Statistical analysis The statistical analysis was performed using SigmaStat software (version 3.5). The data were analyzed to verify the normal distribution and the homogeneity of the variance. The results were analyzed statistically using one-way analysis of variance (ANOVA), followed by Tukey post-hoc test (α = 0.05). Normality test failed for water sorption data, which were analyzed by Kruskall-Wallis and Dunn’s method (α = 0.05). 3. Results 3.1 Monomer synthesis and characterization The trimethacrylate monomer was successfully synthesized by a two-step reaction: cardanol reacted with hydrogen peroxide to afford CNE, which was converted to CTMA by the reaction with methacrylic anhydride (Fig. 1 ). The monomer characterization by FT-IR (Fig. 2 ), 1 H and 13 C NMR (Fig. 3 ) confirmed the presence of the methacrylate groups in CTMA. The characteristic bands/peaks are listed as follows: CNE : FT-IR (ATR, cm − 1 ): 3374; 2925; 2854; 1588; 1455; 1352; 1272; 1229; 1154; 1072; 998; 943; 872; 826; 779; 749; 724; 694; 637; 596; 562. NMR 1 H (300 MHz, CDCl 3 , ppm): δ 7.13 (t); 6.72 (d); 6.68 (d); 5.89 (m); 5.16 (m); 3.17 (m); 2.95 (m); 2.55 (t); 1.79 (m); 1.59 (m); 1.30 (m); 0.90 (m). NMR 13 C (300 MHz, CDCl 3 , ppm): δ 155.98; 144.97; 129.45; 120.83; 117.57; 115.55; 112.76; 57.66; 35.86; 31.16; 29.80; 27.90; 26.94; 26.66; 22.66; 14.08. CTMA : FTIR (ATR, cm − 1 ): 2926; 2855; 1736; 1637; 1587; 1451; 1378; 1294; 1233; 1148; 1121; 1002; 941; 807; 780; 723; 693; 647. NMR 1 H (300 MHz, CDCl 3 , ppm): δ 7.20; 7.04 (d); 6.94 (d); 6.34 (d); 5.74 (d); 5.16 (m); 2.61 (t); 2.07 (s); 1.97 (t); 1.63 (m); 1.54 (m); 1.31 (m); 0.90 (m). NMR 13 C (300 MHz, CDCl 3 , ppm): δ 166.01; 151.09; 144.44; 136.16; 132.36; 128.84; 126.88; 125.66; 121.30; 118.70; 115.55; 112.35; 72.65; 57.14; 35.60. 30.98; 29.54; 27.72; 25.44; 22.42; 18.20; 13.88. In the FT-IR spectra (Fig. 2 ), the stretch of the C-H sp 2 (aliphatic) bond at 3009 cm − 1 is only observed in CN. The stretch of the C-O-C (oxirane ring) bond at 826 cm − 1 is presented in CNE, demonstrating the successful epoxidation. In the FT-IR spectrum of CTMA, the stretching bands at 826 cm − 1 and at 3300 cm − 1 , characteristic of the O-H bond of the phenol, disappeared, and an absorption band was detected at 1736 cm − 1 , corresponding to the bond C = O (carbonyl from methacrylate). Relative to 1 H NMR and 13 C NMR spectra, CN showed a signal at the range of δ 5.37–5.43 ppm (Fig. 3 a - dotted rectangle 1) relative to the olefinics hydrogens of the lateral chain, that was absent in CNE and CTMA. The signal at the range of δ 2.75–3.17 (Fig. 3 a - dotted rectangle 2) is attributed to the oxirane ring of CNE, also confirmed by the signal at 57.66 ppm in the 13 C NMR (Fig. 3 b – dotted rectangle 2), which has practically disappeared in CTMA spectra. Between δ 5.74–6.34 ppm, signals corresponding to the vinylic hydrogens (Fig. 3 a - dotted rectangle 4) were observed, along with a singlet at δ 2.07 ppm attributed to the methyl protons of the methacrylate group of CTMA (Fig. 3 a – dotted rectangle 3). The 13 C NMR confirmed the presence of the methacrylate group in CTMA showing the terminal methyl group at δ 18.20 ppm (Fig. 3 b – dotted rectangle 3) and the signal at the range of 166 ppm (Fig. 3 b – dotted rectangle 5), characteristic of the carbonyl (C = O). Also, the signal at the range of 72.65 ppm is characteristic of the C-O-C bonds of the methacrylate group (Fig. 3 b – dotted rectangle 6). 3.2 Degree of conversion The degree of conversion results (means and standard deviations) are depicted in Fig. 4 , which indicates that there was no statistically significant difference (p = 0.052) found among the groups regarding the degree of conversion data. 3.3 Water sorption and solubility The outcomes of water sorption and solubility of the experimental resin composites are summarized in Fig. 5 . The CTMA-40 and CTMA-50 groups showed significantly lower water sorption results compared to the control group (p < 0.05). Furthermore, the incorporation of CTMA (10, 20, 40 and 50%) into composites significantly reduced the solubility when compared to Bis-GMA-based composite (p < 0.05). 3.4 Viscosity The viscosity of the filler-free resins exhibited a linear a linear relationship with increasing shear rate, suggesting Newtonian behavior for all resins. Table 2 presents the viscosity outcomes measured at 500 s − 1 shear rate. All of the CTMA groups obtained significantly lower viscosities compared to the control, and the incorporation of CTMA gradually reduced the viscosity of the experimental resins (p < 0.05). Table 2 Mean values ± standard deviation (SD) of viscosity for each group Composites Mean viscosity (SD) (cP a ) p-value (< 0.001) Control 251.83 (0.50) A CTMA-10 184.62 (0.55) B CTMA-20 155.24 (1.35) C CTMA-40 133.67(0.48) D CTMA-50 123.99(0.29) E a cP: centipoise = 0.01 P. Different capital letters present statistically significant difference among the viscosities of the groups (p < 0.05). 3.5 Thermogravimetric analysis The TGA thermograms demonstrate that all samples were in general stable up to 200 ºC (Fig. 6 ). The degradation characteristic temperatures were summarized in Table 3 , including the initial decomposition temperature (T d5% ), representing 5% weight loss) and the temperature corresponding to the maximum decomposition rate (T max ). The addition of a maximum of 20% CTMA (CTMA-10 and CTMA-20) to resins slightly increased the initial thermal degradation temperature, thereby enhancing the thermal degradation stability of the composites compared to the control. Conversely, the addition of higher concentrations of CTMA (CTMA-40 and CTMA-50) led to a decrease of the initial thermal degradation temperature. Table 3 Thermogravimetric analysis (TGA) results Composites T máx a T d5% b Control 418 ºC 286 ºC CTMA-10 422 ºC 295 ºC CTMA-20 423 ºC 294 ºC CTMA-40 427 ºC 247 ºC CTMA-50 427 ºC 259 ºC a T máx : maximum decomposition. b T d5% : 5% decomposition. 3.6 Dynamic mechanical analysis The storage modulus for all groups decreased with rising temperature (Fig. 7 a). The control composite obtained the highest value of storage modulus at the rubbery zone (180 ºC), which decreased slightly with increasing CTMA content. At 37 ºC, the CTMA-20 resin exhibited the highest storage modulus (840.42 MPa) among the CTMA-based resins (Fig. 7 a and Table 4 ). The progressive addition of CTMA resulted in a decline in T g (determined as the maximum of the tan δ versus temperature) in comparison to the control (Table 4 ). When CTMA was used as a comonomer, all resin composites showed higher tan δ peaks than the control, especially for CTMA-40 and CTMA-50 (Fig. 7 b). Also, regarding the width of tan δ peaks, the samples revealed similar wide peaks. Table 4 Dynamic mechanical analysis (DMA) results Composites Storage modulus at 37 ºC (MPa a ) Storage modulus at 180 ºC (MPa a ) Tg (ºC) b Control 981.84 31.34 141 CTMA-10 738.46 25.89 128.7 CTMA-20 840.42 25.10 125 CTMA-40 700.06 20.39 119.2 CTMA-50 786.09 18.36 115.1 a MPa: megapascal. b Glass transitions temperatures were determined as the maximum of the tan δ versus temperature. 3.7 Flexural strength and elastic modulus The outcomes of the flexural strength (FS) and elastic modulus (E) are depicted in Fig. 8 . All composites formulated with CTMA showed FS and E similar to the control (p > 0.05). The CTMA-20 material achieved the E highest values, which was statistically significant different from CTMA-40 composite (p = 0.028). 4. Discussion The present investigation revealed that the first and second hypothesis must be accepted, once the physicochemical properties tested were not negatively affected by the addition of CTMA and there was a reduction in the viscosity, water sorption and solubility in comparison with BisGMA-based resin by the addition of the novel trimethacrylate monomer. Also, CTMA groups attained mechanical properties similar to traditional systems based on Bis-GMA. Consequently, third hypothesis should be accepted. An effective polymerization plays a very important role on the physicochemical and mechanical properties of resin-based dental materials. Double bond conversion of multi-methacrylate polymers is rarely complete because of the flexibility of monomers during propagation, and due to the limited mobility of partially cured macromolecules as the reaction progresses [ 12 ]. The long flexible carbon chain of CTMA probably induced a delayed gelation, increasing the mobility of the active species after the formation of microgels during polymerization and achieving a similar degree of conversion as the traditional Bis-GMA/TEGDMA control resin. The long aliphatic carbon chain of CTMA, devoid of polar hydroxyls, also contributes to its high hydrophobicity [ 17 ], thus explaining why CTMA groups showed lower water sorption. This may have led to smaller amounts of leachable monomers from CTMA composites, and overall soluble products, along with the acceptable degree of conversion. In contrast to CTMA, the BisGMA-rich composites may be partially degraded into BPA when they are in contact with human saliva [ 5 ] and might contaminate the body. Apart from reduced water sorption and solubility, a relatively low viscosity is desired for monomers employed in resin-based dental materials, in order to facilitate handling and incorporation of filler particles. The Bis-GMA content reduces side-chain mobility, as it increases the formation of strong hydrogen bonds through its hydroxyls [ 22 ]. The observed decrease in viscosity was attributed to the substitution of the viscous Bis-GMA by CTMA, since the latter has a high molecular weight but a long flexible carbon chain free of hydroxyl groups, thereby not forming hydrogen bonds which increase viscosity. This assertion finds validation in CTMA-50 group, which eliminated all content of Bis-GMA and the consequent formation of hydrogen bonds, resulting in a substantial reduction in the viscosity of the composites. In terms of thermal degradation stability, the incorporation of CTMA in composites up to 20% was able to improve it, which could be attributed to the bulky aromatic structure and long side alkyl chains of CTMA. These characteristics may have prevented the packing of the polymer chains leading to an increase in the voids in the system. Also, all groups were stable up to 200 ºC (Fig. 6 ), indicating a similar and acceptable thermal stability of resin composites for safe use in the oral cavity. The survey of Jaillet et al. (2014) investigated the thermal degradation of novel vinylester prepolymers from cardanol in comparison to diglycidyl ether of bisphenol A (DGEBA), which showed similar thermal stability [ 23 ]. A maximum decomposition rate around 430°C for cardanol-based resins was found, quite similar to the values obtained for CTMA-based resin composites (Table 3 ; T máx : 422 to 427°C). Concerning mechanical properties, dynamic mechanical analysis provides information about the properties of polymer networks, such as storage modulus and glass transition temperature (T g ), by evaluating the structure and stiffness of the materials [ 21 ]. Control composite obtained the highest value of storage modulus at the rubbery zone (180 ºC), indicating greater entanglement of polymer networks. Crosslinking density is an important variable in the viscoelastic behavior of the polymers, and, typically, resin-based materials with multimethacrylates are highly crosslinked polymer networks, once a higher number of functionalities is beneficial for the storage modulus in the rubbery zone [ 12 ]. However, our results showed that the trimethacrylate addition reduced the storage modulus, and, therefore, the crosslinking density of the composites. Furthermore, the incorporation of CTMA revealed a plasticizing effect on Bis-GMA composites, preventing close packing between the polymer backbones, as seen in the lowering of T g in comparison to the control (Table 4 ). However, the T g obtained by CTMA composites are still above body temperature and food/beverage consumed (> 115 ºC); therefore, their physical and mechanical properties are preserved, ensuring optimal intraoral performance of these materials. The height of the maximum tan δ peak on DMA reflects the extent of mobility of the polymer chain segments as a function of temperature. When CTMA was used as a comonomer, all composites showed higher tan δ peaks than the control. This result reveals a high mobility of the CTMA polymer networks (especially for CTMA-40 and CTMA-50) due to the flexible long carbon chain, causing an increase in the viscous behavior (less energy is stored in the material) at the expense of the elastic component. Also, regarding the width of tan δ peaks, the samples revealed similar wide peaks, which means that the glass transition occurs over a wide temperature range. This wide glass transition is apparently related to the chain-growth polymerization in heterogeneous networks and usually occurs with increasing crosslink density of the polymer network [ 21 ]. One of the few properties correlated with the clinical performance of resin composite restorations is the flexural strength, as this in vitro test is correlated to the clinical wear and tensions undergone in restorations and plays an important role in the acceptance of restorative materials [ 24 ]. The statistical analysis demonstrated similarity of mechanical properties of CTMA-based composites when compared to control. The main reason that could explain this behavior is the CTMA chemical structure, which has one aromatic ring that confer high mechanical stability to the material similar to the rigid backbone bisphenol-A structure of the Bis-GMA monomer. The similar degree of conversion outcomes may also correlate to the results obtained for flexural strength and elastic modulus, since physical and mechanical properties of resin-based composites are influenced by the degree of polymerization [ 25 ]. As Bis-GMA based resin composites have decades of clinical success and currently still are standard composites employed around the world. The proposed newly synthesized monomer CTMA then achieved similar or superior physicochemical properties to the control Bis-GMA, proving the clinical suitability, with the advantages of lacking bisphenol-A as well as CTMA-synthesis thresholds from a plant-derived compound, thereby turning this a monomer derived from a renewable source. 5. Conclusion In summary, this research is the first to exhibit the synthesis of a CNSL-derived trimethacrylate monomer and its possible application in resin-based dental materials. Incorporation of CTMA into resin composites reduced its viscosity, water sorption and solubility without interfering in flexural strength and polymerization when compared to Bis-GMA-based material. Within the limitation of this study, CTMA is a feasible co-monomer for dental restorative materials, as a Bis-GMA substitute. Declarations Ethics approval and consent to participate Not applicable. Conflict of Interest: Authors Madiana Magalhães Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled “synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid”, which includes the CTMA monomer used in this study. Competing Interests Authors Madiana Magalhães Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled “synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid”, which includes the CTMA monomer used in this study. Funding This study was funded by National Counsel of Technological and Scientific Development (CNPq - Brazil), by Coordination for the Improvement of Higher Education Personnel (CAPES - Brazil) and by Cearense Foundation for Scientific and Technological Development Support (FUNCAP – Ceará, Brazil). Author Contribution All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Moreira, M.M.; Silva, A.L.; Pereira, R.C.S.; and Rocha da Silva, L.R. Moreira, M.M. prepared figures 1, 4, 5, and 8; Rocha da Silva, L.R. prepared figures 2 and 3; Pereira, R.C.S. prepared figure 6; and Lomonaco, D. prepared figure 7. The first draft of the manuscript was written by Moreira, M.M., and all authors critically revised the manuscript for important intellectual content. Supervision was provided by Lomonaco D. and Feitosa V.P. All authors have read and approved the final manuscript. Data availability The authors affirm that the data supporting the results of this investigation are included in the manuscript. If any raw data files are required in a different format, they can be obtained from the corresponding author upon reasonable request. References Stansbury JW (2012) Dimethacrylate network formation and polymer property evolution as determined by the selection of monomers and curing conditions. Dent Mater 28(1):13–22. https://doi.org/10.1016/j.dental.2011.09.005 Szczesio-Wlodarczyk A, Polikowski A, Krasowski M, Fronczek M, Sokolowski J, Bociong K (2022) The Influence of Low-Molecular-Weight Monomers (TEGDMA, HDDMA, HEMA) on the Properties of Selected Matrices and Composites Based on Bis-GMA and UDMA. Mater (Basel) 15(7):2649. https://doi.org/10.3390/ma15072649 González-López JA, Pérez-Mondragón AA, Cuevas-Suárez CE, Trejo-Carbajal N, Herrera-González AM (2020) Evaluation of dental composites resins formulated with non-toxic monomers derived from catechol. J Mech Behav Biomed Mater 104:103613. https://doi.org/10.1016/j.jmbbm.2019.103613 Cimmino I, Fiory F, Perruolo G, Miele C, Beguinot F, Formisano P, Oriente F (2020) Potential mechanisms of bisphenol A (BPA) contributing to human disease. Int J Mol Sci 21(16):5761. https://doi.org/10.3390/ijms21165761 De Nys S, Duca RC, Vervliet P, Covaci A, Boonen I, Elskens M, Vanoirbeek J, Godderis L, Van Meerbeek B, Van Landuyt KL (2021) Bisphenol A as degradation product of monomers used in resin-based dental materials. Dent Mater 37(6):1020–1029. https://doi.org/10.1016/j.dental.2021.03.005 Sun Y, Zhou Z, Jiang H, Duan Y, Li J, Liu X, Hong L, Zhao C (2022) Preparation and evaluation of novel bio-based Bis-GMA-free dental composites with low estrogenic activity. Dent Mater 38(2):281–293. https://doi.org/10.1016/j.dental.2021.12.010 Jun SK, Cha JR, Knowles JC, Kim HW, Lee JH, Lee HH (2020) Development of Bis-GMA-free biopolymer to avoid estrogenicity. Dent Mater 36(1):157–166. https://doi.org/10.1016/j.dental.2019.11.016 Vasconcelos e Cruz J, Delgado AH, Félix S, Brito J, Gonçalves L, Polido M (2022) Improving Properties of an Experimental Universal Adhesive by Adding a Multifunctional Dendrimer (G-IEMA): Bond Strength and Nanoleakage Evaluation. Polym (Basel) 14(7):1462. https://doi.org/10.3390/polym14071462 Childress KK, Alim MD, Hernandez JJ, Stansbury JW, Bowman CN (2020) Additive manufacture of lightly crosslinked semicrystalline thiol–enes for enhanced mechanical performance. Polym Chem 11(1):39–46. https://doi.org/10.1039/C9PY01452G Pérez-Mondragón AA, Cuevas-Suárez CE, González-López JA, Trejo-Carbajal N, Meléndez-Rodríguez M, Herrera-González AM (2020) Preparation and evaluation of a BisGMA-free dental composite resin based on a novel trimethacrylate monomer. Dent Mater 36(4):542–550. https://doi.org/10.1016/j.dental.2020.02.005 Gauthier MA, Zhang Z, Zhu XX (2009) New dental composites containing multimethacrylate derivatives of bile acids: a comparative study with commercial monomers. ACS Appl Mater Interfaces 1(4):824–832. https://doi.org/10.1021/am8002395 Park J, Ye Q, Singh V, Kieweg SL, Misra A, Spencer P (2012) Synthesis and evaluation of novel dental monomer with branched aromatic carboxylic acid group. J Biomed Mater Res B Appl Biomater 100(2):569–576. https://doi.org/10.1002/jbm.b.31987 Moreira MM, da Silva LRR, Mendes TAD, Santiago SL, Mazzetto SE, Lomonaco D, Feitosa VP (2018) Synthesis and characterization of a new methacrylate monomer derived from the cashew nut shell liquid (CNSL) and its effect on dentinal tubular occlusion. Dent Mater 34(8):1144–1153. https://doi.org/10.1016/j.dental.2018.04.011 Moreira MM, Farrapo MT, Pereira RDCS, da Silva LRR, Koller G, Watson T, Feitosa VP, Lomonaco D (2022) Methacrylic monomer derived from cardanol incorporated in dental adhesive as a polymerizable collagen crosslinker. Dent Mater 38(10):1610–1622. https://doi.org/10.1016/j.dental.2022.08.008 Lemos MVS, Araujo-Neto VG, Lomonaco D, Mazzetto SE, Feitosa VP, Santiago SL (2022) Evaluation of Novel Plant-derived Monomers-based Pretreatment on Bonding to Sound and Caries-affected Dentin. Oper Dent 47(1):E12–E21. https://doi.org/10.2341/20-138-L Lomonaco D, Mele G, Mazzetto S (2017) Cashew Nutshell Liquid (CNSL): From an Agro-industrial Waste to a Sustainable Alternative to Petrochemical Resources. In: Anilkumar P (ed) Cashew Nut Shell Liquid: A Gold Field for Functional Materials, 1st edn. Springer International Publishing, pp 19–38 Feitosa VP, Sauro S, Ogliari FA, Ogliari AO, Yoshihara K, Zanchi CH, Correr-Sobrinho L, Sinhoreti MA, Correr AB, Watson TF, Van Meerbeek B (2014) Impact of hydrophilicity and length of spacer chains on the bonding of functional monomers. Dent Mater 30(12):e317–e323. https://doi.org/10.1016/j.dental.2014.06.006 Pereira RCS, Rocha da Silva LR, Carvalho BA, Mattos AL, Mazzetto SE, Lomonaco D (2021) Development of Bio-based Polyurethane Wood Adhesives from Agroindustrial Waste. J. Polym Environ 1–14. https://doi.org/10.1007/s10924-021-02331-y ISO (2009) ISO 4049:2009 — Dentistry — polymer-based restorative materials Da Silva LRR, Carvalho BA, Pereira RCS, Diogenes OBF, Pereira UC, Da Silva KT, Araújo WS, Mazzetto SE, Lomonaco D (2022) Bio-based one-component epoxy resin: Novel high-performance anticorrosive coating from agro-industrial byproduct. Prog Org Coat 167:106861. https://doi.org/10.1016/j.porgcoat.2022.106861 Park JG, Ye Q, Topp EM, Lee CH, Kostoryz EL, Misra A, Spencer P (2009) Dynamic mechanical analysis and esterase degradation of dentin adhesives containing a branched methacrylate. J Biomed Mater Res B Appl Biomater 91(1):61–70. https://doi.org/10.1002/jbm.b.31374 Pereira LDE, Neto MPC, Pereira RG, Schneider LFJ (2021) Influence of resin matrix on the rheology, translucency, and curing potential of experimental flowable composites for bulk-fill applications. Dent Mater 37(6):1046–1053. https://doi.org/10.1016/j.dental.2021.03.003 Jaillet F, Nouailhas H, Auvergne R, Ratsimihety A, Boutevin B, Caillol S (2014) Synthesis and characterization of novel vinylester prepolymers from cardanol. Eur J Lipid Sci Technol 116(7):928–939. https://doi.org/10.1002/ejlt.201300487 Heintze SD, Ilie N, Hickel R, Reis A, Loguercio A, Rousson V (2017) Laboratory mechanical parameters of composite resins and their relation to fractures and wear in clinical trials—A systematic review. Dent Mater 33(3):e101–e114. https://doi.org/10.1016/j.dental.2016.11.013 Wu J, Zhao Z, Hamel CM, Mu X, Kuang X, Guo Z, Qi HZ (2018) Evolution of material properties during free radical photopolymerization. J Mech Phys Solids 112:25–49. https://doi.org/10.1016/j.jmps.2017.11.018 Additional Declarations Competing interest reported. Authors Madiana Magalhães Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled “synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid”, which includes the CTMA monomer used in this study. Cite Share Download PDF Status: Published Journal Publication published 08 Oct, 2024 Read the published version in Clinical Oral Investigations → Version 1 posted Editorial decision: Revision requested 17 Jul, 2024 Reviews received at journal 16 Jul, 2024 Reviews received at journal 15 Jul, 2024 Reviewers agreed at journal 12 Jul, 2024 Reviewers agreed at journal 04 Jul, 2024 Reviewers invited by journal 04 Jul, 2024 Editor assigned by journal 28 Jun, 2024 Submission checks completed at journal 28 Jun, 2024 First submitted to journal 27 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4648523","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":328160256,"identity":"545a4b5c-6fce-47b7-84e8-6d227439ab7b","order_by":0,"name":"Madiana Magalhães Moreira","email":"data:image/png;base64,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","orcid":"","institution":"Universidade Federal do Ceará","correspondingAuthor":true,"prefix":"","firstName":"Madiana","middleName":"Magalhães","lastName":"Moreira","suffix":""},{"id":328160258,"identity":"df62570c-e62e-4c12-9b3b-e06d0c9ca5a4","order_by":1,"name":"Ana Larissa da Silva","email":"","orcid":"","institution":"Paulo Picanço School of Dentistry","correspondingAuthor":false,"prefix":"","firstName":"Ana","middleName":"Larissa da","lastName":"Silva","suffix":""},{"id":328160259,"identity":"27a3b354-0714-471e-b4c2-65f15437036e","order_by":2,"name":"Rita de Cássia Sousa Pereira","email":"","orcid":"","institution":"Universidade Federal do Ceará","correspondingAuthor":false,"prefix":"","firstName":"Rita","middleName":"de Cássia Sousa","lastName":"Pereira","suffix":""},{"id":328160264,"identity":"c8ee8dee-05b6-4637-800a-1bc0b3c21e46","order_by":3,"name":"Lucas Renan Rocha da Silva","email":"","orcid":"","institution":"Universidade Federal do Ceará","correspondingAuthor":false,"prefix":"","firstName":"Lucas","middleName":"Renan Rocha da","lastName":"Silva","suffix":""},{"id":328160267,"identity":"68e303d9-41fd-4ad5-b929-36c1b5fdebc5","order_by":4,"name":"Victor Pinheiro Feitosa","email":"","orcid":"","institution":"University of Iowa","correspondingAuthor":false,"prefix":"","firstName":"Victor","middleName":"Pinheiro","lastName":"Feitosa","suffix":""},{"id":328160269,"identity":"12fbe63a-54d6-4da6-aa68-9a3b4466e43d","order_by":5,"name":"Diego Lomonaco","email":"","orcid":"","institution":"Universidade Federal do Ceará","correspondingAuthor":false,"prefix":"","firstName":"Diego","middleName":"","lastName":"Lomonaco","suffix":""}],"badges":[],"createdAt":"2024-06-27 12:25:41","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4648523/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4648523/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00784-024-05959-x","type":"published","date":"2024-10-08T15:58:01+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60845865,"identity":"730fb7ed-82ee-465b-a9c1-b2fc61263fb8","added_by":"auto","created_at":"2024-07-22 18:52:10","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":423824,"visible":true,"origin":"","legend":"\u003cp\u003eSynthetic route: unsaturated cardanol (CN) was epoxidized with hydrogen peroxide (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e), in order to incorporate an oxirane ring (orange) where the unsaturation in the aliphatic carbon chain (green) was located and form cardanol epoxy (CNE). CNE was esterified with methacrylic anhydride in order to incorporate three methacrylate pendants (purple): where the oxirane ring of CNE was located and also to substitute the phenolic hydroxyl, achieving the final monomer cardanol trimethacrylate (CTMA)\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/7b4ec3067db6421ac4705bc2.jpg"},{"id":60845571,"identity":"a81f337a-97e3-4098-98da-82653b88267b","added_by":"auto","created_at":"2024-07-22 18:44:10","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":595072,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra obtained from the monomers: unsaturated cardanol (CN; top black spectrum), cardanol epoxy (CNE; middle orange spectrum) and cardanol trimethacrylate (CTMA; bottom purple spectrum)\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/9809cb440112e9c89cc202d7.jpg"},{"id":60845024,"identity":"8cf13d4c-e8dd-4229-b660-fed362f2e0c0","added_by":"auto","created_at":"2024-07-22 18:36:10","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1890134,"visible":true,"origin":"","legend":"\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eH NMR (a) and \u003csup\u003e13\u003c/sup\u003eC NMR (b) spectra of the monomers: cardanol unsaturated (CN; top black spectrum), cardanol epoxy (CNE; middle orange spectrum) and cardanol trimethacrylate (CTMA; bottom purple spectrum)\u003c/p\u003e","description":"","filename":"Fig3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/74ce1b695a6a228c174b1f71.jpeg"},{"id":60845020,"identity":"bbe50543-6268-4643-a36a-8130437c6c6c","added_by":"auto","created_at":"2024-07-22 18:36:10","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":19843,"visible":true,"origin":"","legend":"\u003cp\u003eMeans and standard deviations obtained from the degree of conversion (%) analysis. Identical capital letters represent statistically similar degree of conversion (p\u0026gt;0.05)\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/1927dbb73e467594d52afac6.jpg"},{"id":60845569,"identity":"d4c83e78-3a94-4d5f-a6f6-563f13088fb7","added_by":"auto","created_at":"2024-07-22 18:44:10","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":30012,"visible":true,"origin":"","legend":"\u003cp\u003eOutcomes of water sorption (medians and interquartile ranges) and solubility (means and standard deviations) tests of the resin composites (µg/mm³). Different capital letters present statistically significant difference among the water sorption of the groups (p\u0026lt;0.05). Different lower case letters show significant difference between solubility of the composites (p\u0026lt;0.05)\u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/5d1ab139a3d47c9fd06052f5.jpg"},{"id":60845027,"identity":"4a9d75a5-a80a-44b8-9518-ba1dd8f4a0e9","added_by":"auto","created_at":"2024-07-22 18:36:10","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":299840,"visible":true,"origin":"","legend":"\u003cp\u003eThermogravimetric analysis (TGA): comparison of the mass loss of resin composites as a function of the temperature increase\u003c/p\u003e","description":"","filename":"Fig6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/c96bf84d7330e697826c0e64.jpeg"},{"id":60845026,"identity":"a25b4cda-7a2a-4555-b651-96a03c7c6841","added_by":"auto","created_at":"2024-07-22 18:36:10","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":220811,"visible":true,"origin":"","legend":"\u003cp\u003eDynamic mechanical analysis (DMA): comparison of the storage modulus (a) and tan δ (b) versus temperature curves for experimental composites. Glass transitions temperature (T\u003csub\u003eg\u003c/sub\u003e) of the materials were determined as the maximum of the tan δ versus temperature (b)\u003c/p\u003e","description":"","filename":"Fig7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/1ead017385204007900eed1d.jpeg"},{"id":60845023,"identity":"0b5385bd-7afb-44da-bb65-04b4167c4d4a","added_by":"auto","created_at":"2024-07-22 18:36:10","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":52667,"visible":true,"origin":"","legend":"\u003cp\u003eMean values (MPa) ± standard deviation of flexural strength (a) and elastic modulus (b). Different capital letters present statistically significant difference between the resin composites (p\u0026lt;0.05)\u003c/p\u003e","description":"","filename":"Fig8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/647e26f36a69406a98a1dbb1.jpeg"},{"id":66597261,"identity":"f8078914-b242-4994-acce-fa33a0e38488","added_by":"auto","created_at":"2024-10-14 16:09:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4290327,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4648523/v1/d29d3042-d787-476f-8191-d2ff82e6f17e.pdf"}],"financialInterests":"Competing interest reported. Authors Madiana Magalhães Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled “synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid”, which includes the CTMA monomer used in this study.","formattedTitle":"Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eThe structure and functional groups of the monomers employed in dental materials strongly influence polymer network formation and characteristics, such as mechanical properties, degree of conversion, crosslinking formation and viscosity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Bisphenol A glycidyl methacrylate (Bis-GMA) is the most commonly monomer used in polymer matrix formulations due to its high molecular weight, low polymerization shrinkage and excellent mechanical properties [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. However, its high viscosity, attributed to intermolecular hydrogen bond formation, demands the addition of low molecular weight monomers, such as hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. TEGDMA is widely used in resin composites to reduce viscosity and increase filler incorporation; however, it reduces mechanical properties and increases polymerization shrinkage and water sorption [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMoreover, Bis-GMA is a derivative of bisphenol A (BPA), a synthetic compound which mimics the estrogen hormone, being considered an endocrine disruptor that, even at low doses, may contribute to the pathogenesis of several diseases [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Exposure to BPA in the oral cavity has been explored, as this compound can be released by degradation of derivatives used in the formulation of resin-based materials, such as Bis-GMA [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Worryingly, the potential impact of this release on human health remains uncertain.\u003c/p\u003e \u003cp\u003eIn this constant search for improvements in biocompatibility, Bis-GMA free compounds have been widely researched, such as dimethacrylate monomers from bio-based material creosol [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], isosorbide-based monomer [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], and dendrimers [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]; as well as new resin-based systems, such as thiol-enes [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In order to improve long-term performance of dental materials, multimethacrylates have been investigated. Although some trimethacrylates exhibited mechanical properties comparable to the Bis-GMA composites, they resulted in a lower polymerization rate, higher viscosity, water sorption and solubility [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Contrariwise, Park et al. (2012) concluded that a trimethacrylate monomer added to dentin adhesives reduced viscosity and increased crosslink density and double bond conversion [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong the natural and renewable sources that has been employed for the synthesis of new monomers for dental applications, the cashew nut shell liquid (CNSL) stands out [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], a biomass rich in phenolic lipids that represents approximately 25% of the cashew nut weight [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Technical CNSL is a byproduct of the cashew nut manufacturing industry, composed primarily of cardanol (67.8 to 94.6%) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This monomer exhibits structural characteristics favorable for use in dental materials, such as long carbon chain and several reaction sites (CN, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), suitable for the incorporation of functional groups.\u003c/p\u003e \u003cp\u003eThe use of monomers with long spacer carbon chain is favorable since they provide high hydrophobicity, resulting in lower water sorption, reduced polymer degradation, and greater hydrolytic stability to the polymer [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Moreover, the aromatic ring of cardanol contributes to relative stiffness and polymeric strength, while the alkorganicyl chain provides flexibility, reducing its viscosity and the subsequent requirement of considerable incorporation of low molecular weight monomers. Supported by these promising structural characteristics of the molecule, cardanol methacrylate epoxidized monomer was synthesized and employed in a resin-based desensitizer, achieving the greatest reduction in dentin permeability and most homogeneous and occluded surface among desensitizers tested, even after acid challenge [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Recently, cardanol was also functionalized with a methacrylate and the synthesized monomer reduced the adhesive resin solubility without interfering in polymerization [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTherefore, cardanol highlights as a molecule with attractive structural features for the synthesis of new methacrylate monomers, bringing alternatives to improve the properties of dental materials with wide range of dental applications. The synthesis of a trimethacrylate from cardanol, as the major component of the CNSL and with promising physicochemical and structural properties, could generate hydrophobic resin-based materials with high mechanical strength, polymer crosslinking and hydrolytic stability, also reducing the use of BPA-derived monomers.\u003c/p\u003e \u003cp\u003eThe aim of this manuscript was to analyze the effect of incorporating cardanol trimethacrylate (CTMA) monomer derived from CNSL, as a substitute for Bis-GMA, on the physicochemical and mechanical properties of experimental resin composites. The hypotheses of the study are that the addition of CTMA in resin composites (1) does not jeopardize chemical properties (degree of conversion and thermal-degradation), (2) reduces the viscosity, water sorption and solubility, and (3) promotes mechanical properties similar to traditional Bis-GMA-based systems.\u003c/p\u003e"},{"header":"2 Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Reagents\u003c/h2\u003e \u003cp\u003eCardanol was kindly supplied by Satya Chemicals (Eluru, India). Formic acid (85%), hydrogen peroxide (35%), ethyl acetate, sodium bicarbonate, and anhydrous sodium sulfate were used as received from LabSynth (S\u0026atilde;o Paulo, Brazil). BHT (3,5-Di-tert-4-butylhydroxytoluene), and methacrylic anhydride were purchased from Sigma-Aldrich (St. Louis, USA) and used as received. Silica gel (63\u0026ndash;200 \u0026micro;m; Sigma-Aldrich, St. Louis, USA) was employed in the chromatographic separations.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Synthesis of cardanol trimethacrylate (CTMA)\u003c/h2\u003e \u003cp\u003eThe organic synthesis of the methacrylic monomer was performed according to the synthetic route illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, initially involving an epoxidation reaction of the unsaturated carbon chain of cardanol, followed by replacement of the phenolic hydroxyl and oxirane ring-opening to incorporate methacrylic groups.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe intermediate product cardanol epoxy (CNE) was obtained, as performed by Pereira et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] with modifications. The synthesis of CNE involved the epoxidation of the unsaturations of cardanol (CN) with performic acid formed in situ from the reaction between formic acid and hydrogen peroxide, catalyzed by Amberlite IR 120H, using the molar ratio of 1.0: 0.5: 3.0 (unsaturation: formic acid: hydrogen peroxide). In a round bottom flask (100 mL), 10 g of cardanol (56.8 mmol of unsaturation) was weighed followed by the addition of 1.26 mL of formic acid (28.4 mmol) and 2 g of Amberlite IR 120H (20 wt % of cardanol). The mixture was kept under magnetic stirring for 10 minutes. Then, using a burette, 16.3 mL of hydrogen peroxide (170.5 mmol) was added dropwise under constant stirring at room temperature. After that, the mixture was heated in a silicone bath at 65\u0026deg;C and continuously stirred for 4 hours to obtain CNE as a reddish-brown oil (90% yield).\u003c/p\u003e \u003cp\u003eCardanol trimethacrylate (CTMA) monomer was obtained by a simultaneously oxirane ring-opening and hydroxyl substitution esterification reaction of CNE with methacrylic anhydride in a molar ratio of 1:1, and 2.5 wt % of triphenylphosphine. Also, 0.01 wt % BHT was added to avoid spontaneous polymerization. CTMA synthesis was carried out under microwave irradiation (Milestone microwave reactor; StartSYNTH, Shelton, USA) operating with 2.45 GHz frequency and 800 W maximum power. The procedure begins by weighing 4 g of CNE (12.6 mmol) in a round bottom flask (25 mL), followed by the addition of 2.0 mL of methacrylic anhydride (12.6 mmol) and 0.1 g of triphenylphosphine (0.381 mmol). The flask was connected to a 50 cm Vigreux condenser and placed in the microwave cavity under constant magnetic stirring, programmed to ramp up from room temperature to 80 \u0026ordm;C within 2 minutes and maintain this temperature for 20 minutes. Subsequently, it was ramped up from 80 \u0026ordm;C to 120 \u0026ordm;C within 2 minutes and maintained for an additional 10 minutes. CTMA was obtained as a light-yellow oil with a yield of 87.4%.\u003c/p\u003e \u003cp\u003eThe progress of the reactions was monitored by thin layer chromatography. At the end of each reaction, mixture was cooled down to room temperature and vacuum filtered to remove the heterogeneous catalyst. The filtrate was transferred to a separation funnel (250 mL), neutralized with saturated sodium bicarbonate solution and extracted with ethyl acetate. Organic phase was collected, dried with anhydrous sodium sulfate, concentrated under reduced pressure and purified through a silica chromatography column to obtain the respective products. Products were kept in a fridge (4 \u0026ordm;C) and protected by aluminum foil to avoid spontaneous polymerization.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Monomer characterization\u003c/h2\u003e \u003cp\u003eCNE and CTMA were characterized by Fourier transform infrared spectroscopy (FT-IR) and \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC nuclear magnetic resonance (NMR) techniques.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Fourier transform infrared vibrational spectroscopy (FT-IR)\u003c/h2\u003e \u003cp\u003eFT-IR spectra were obtained in a Spectrum Frontier (Perkin-Elmer Corp., Norwalk, USA) equipped with zinc selenide (ZnSe) crystal to perform attenuated total reflectance (ATR) analysis. Samples of the isolated monomers were individually dispensed onto the crystal. The wavelength range of analyzes was 4000\u0026ndash;550 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with a resolution of 4 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 32 scans\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Nuclear magnetic resonance (NMR)\u003c/h2\u003e \u003cp\u003eThe \u003csup\u003e1\u003c/sup\u003eH NMR and \u003csup\u003e13\u003c/sup\u003eC NMR spectra were recorded on a nuclear spectrometer instrument (Avance DPX, Bruker, Rheinstetten, Germany) operating at 75 MHz for \u003csup\u003e13\u003c/sup\u003eC and 300 MHz for \u003csup\u003e1\u003c/sup\u003eH. Deuterated chloroform was used to solubilize samples at room temperature.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Experimental resin composite formulation\u003c/h2\u003e \u003cp\u003eExperimental resin was formulated with an organic matrix composed of 50 wt % bisphenol A glycidyl methacrylate (Bis-GMA) and 50 wt % triethylene glycol dimethacrylate (TEGDMA) (Control). CTMA was gradually added, replacing Bis-GMA: 10 wt % (CTMA-10), 20 wt % (CTMA-20), 40 wt % (CTMA-40), and 50 wt % (CTMA-50) as shown on Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Camphoroquinone (0.5 wt %) and ethyl 4-dimethylaminebenzoate (EDAB, 1 wt %) were used, respectively, as photoinitiator and co-initiator with respect to the total amount of monomers.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOrganic matrix composition of the experimental resins\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eMonomeric composition (wt %)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposites\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBis-GMA\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTEGDMA\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCTMA\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003ea\u003c/sup\u003e Bis-GMA: bisphenol A glycidyl methacrylate. \u003csup\u003eb\u003c/sup\u003e TEGDMA: triethyleneglycol\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003edimethacrylate. \u003csup\u003ec\u003c/sup\u003e CTMA: cardanol trimethacrylate.\u003c/p\u003e \u003cp\u003eThe organic matrices of the resins were loaded with 65 wt% of silanated barium borosilicate glass (average particle size of 0,7 \u0026micro;m; Esstech Inc., Essington, USA) and were mechanically manipulated in an amalgamator (Ultramat S, SDI, Victoria, Australia).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Degree of conversion\u003c/h2\u003e \u003cp\u003eThe polymerization of composite resins was evaluated using FT-IR with similar set-up described in characterization section. The unpolymerized composites (1mm height) were placed directly on the diamond ATR crystal and spectra were obtained. Disc-shaped specimens (n\u0026thinsp;=\u0026thinsp;3) were prepared by filling a stainless-steel mold of 6 mm in diameter and 1 mm thickness (Odeme Dental Research, Luzerna, Brazil) with unpolymerized composites, which were covered by a polyester strip and light-cured for 40 seconds on each side with LED curing unit with 1200mW/cm\u0026sup2; irradiance (Valo, Ultradent, South Jordan, USA). Polymerized specimens were evaluated 24 hours after dry storage. The conversion of the methacrylic double bond was monitored by calculating the ratio between the bands 1637 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (aliphatic C\u0026thinsp;=\u0026thinsp;C double bond) / 1608 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (aromatic C\u0026thinsp;=\u0026thinsp;C double bond as internal reference) from cured and uncured composite resins. The analysis was performed in triplicate [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Water sorption and solubility evaluation\u003c/h2\u003e \u003cp\u003eDisk-shaped specimens (n\u0026thinsp;=\u0026thinsp;10) were prepared according to ISO 4049\u0026thinsp;\u0026minus;\u0026thinsp;2009 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], except for the size of specimens, by using a stainless-steel mold of 6 mm in diameter and 1 mm thickness. This matrix was filled with unpolymerized composites, which were covered by a polyester strip, light-cured for 40 seconds on each side with LED (Valo) and stored in a dissector with silica gel at 37\u0026deg;C. To obtain m1, disks were weighed at each 24 hours in precision balance (Marte Cient\u0026iacute;fica AUW220D, S\u0026atilde;o Paulo, Brazil) until a constant dry mass was obtained (variation less than 0.2 mg in three weight measures). Next, the specimens were stored in eppendorfs with 1.5 mL of distilled water at 37\u0026deg;C. After 7 days of immersion, they were washed, gently wiped with absorbent paper and weighed in the precision balance to measure m2. Subsequently, the specimens were dried in the desiccator and weighed daily until a final constant mass was obtained (m3). The volume (V) of the specimens (mm\u003csup\u003e3\u003c/sup\u003e) was calculated by measuring the thickness and diameter with a digital caliper (\u0026plusmn;\u0026thinsp;0.01 mm). Water sorption (WS) and solubility (SL) were calculated (\u0026micro;g/mm\u003csup\u003e3\u003c/sup\u003e) according to the formulas below.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$WS=\\frac{m2-m3}{V} SL=\\frac{m1-m3}{V}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Viscosity measurements\u003c/h2\u003e \u003cp\u003eThe organic matrix of the experimental resins had their viscosities measurements carried out on a rotational rheometer equipped with a 50 mm diameter cone-plate geometry (RST-CPS, Brookfield, Lorch, Germany). For each measurement 1 mL of resin formulation was applied on the lower plate of the rheometer for 5 s before the upper plate was moved downward to adjust the gap to a thickness of 0.045 mm. Each measurement was repeated three times, with a recovery period between each run, and the following parameters were kept constant: shear rate from 1 to 1000 s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 20\u0026deg;C for 120 s [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e2.8 Thermogravimetric Analysis (TGA)\u003c/h2\u003e \u003cp\u003eThe thermal behavior of composites was determined as a function of the increasing temperature using a TGA/SDTA851e thermogravimetric analyzer (Mettler Toledo, Schwerzenbach, Switzerland), in a temperature range from 30 to 800 ◦C at a heating rate of 10 \u003csup\u003e\u0026ordm;\u003c/sup\u003eC/min, under nitrogen atmosphere. Samples (n\u0026thinsp;=\u0026thinsp;3; 10 mg of each organic matrix of the resins) were light-cured for 40 seconds with LED curing unit (Valo). The thermal stability and degradation characteristics of each group were predicted according to the temperatures at which decomposition (weight changes) of the polymers occurs [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e2.9 Dynamic mechanical analysis (DMA)\u003c/h2\u003e \u003cp\u003eThe viscoelastic properties of the resins organic matrix were characterized using a DMA 1 equipment (Mettler Toledo, New Castle, USA) with the following parameters: single-cantilever clamp at a frequency of 1 Hz, amplitude of 10 \u0026micro;m, in a temperature range from 30 to 200 ◦C and at a heating rate of 5 \u003csup\u003e\u0026ordm;\u003c/sup\u003eC/min. The composites were dispensed in a stainless-steel mold (25 mm length, 2 mm width and, 2 mm thickness; Odeme Dental Research) and light-cured (four times of 20 s on each side) using the overlapping method with LED curing unit (Valo). After 24 hours of dry storage, the polymerized samples were subjected to dynamic mechanical analysis. Three specimens of each group were measured (storage modulus and tan δ) and the results were averaged [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e2.10 Flexural strength and elastic modulus\u003c/h2\u003e \u003cp\u003eThe flexural strength was evaluated according to ISO 4049\u0026thinsp;\u0026minus;\u0026thinsp;2009 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], except for the dimensions of the specimens. Bar-shaped specimens (n\u0026thinsp;=\u0026thinsp;6) were obtained by filling a stainless-steel mold (10 mm length, 2 mm width and, 2 mm thickness; Odeme Dental Research) with the experimental composites, which were covered by a polyester strip and light-cured (two times of 20 s on each side) using the overlapping method with LED curing unit (Valo). The polymerized specimens were kept in distilled water at 37 \u003csup\u003e\u0026ordm;\u003c/sup\u003eC for 24 h and then subjected to the three-point bending test performed with a universal testing machine (EMIC 23-2S; Instron, S\u0026atilde;o Jos\u0026eacute; dos Pinhais, Brazil), at a crosshead speed of 1.00 mm/min until fracture. The flexural strength (σ) and elastic modulus (E) were calculated using the following formulas:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\sigma =\\frac{3Fl}{{2bh}^{2}} E= \\frac{{F}_{1 }{l}^{3}}{4b{h}^{3}d}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere:\u003c/p\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;maximum load (N) exerted on the specimen at the point fracture; l\u0026thinsp;=\u0026thinsp;distance between the supports (7 mm); b\u0026thinsp;=\u0026thinsp;width (mm) of the specimen measured immediately prior to testing; h\u0026thinsp;=\u0026thinsp;height (mm) of the specimen measured immediately prior to testing; F\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;load (N) recorded when the deformation stops being directly proportional to the force registered in the graph; d\u0026thinsp;=\u0026thinsp;deflection of the specimen corresponding to the load F\u003csub\u003e1\u003c/sub\u003e [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e2.11 Statistical analysis\u003c/h2\u003e \u003cp\u003eThe statistical analysis was performed using SigmaStat software (version 3.5). The data were analyzed to verify the normal distribution and the homogeneity of the variance. The results were analyzed statistically using one-way analysis of variance (ANOVA), followed by Tukey post-hoc test (α\u0026thinsp;=\u0026thinsp;0.05). Normality test failed for water sorption data, which were analyzed by Kruskall-Wallis and Dunn\u0026rsquo;s method (α\u0026thinsp;=\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Monomer synthesis and characterization\u003c/h2\u003e \u003cp\u003eThe trimethacrylate monomer was successfully synthesized by a two-step reaction: cardanol reacted with hydrogen peroxide to afford CNE, which was converted to CTMA by the reaction with methacrylic anhydride (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The monomer characterization by FT-IR (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC NMR (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) confirmed the presence of the methacrylate groups in CTMA. The characteristic bands/peaks are listed as follows:\u003c/p\u003e \u003cp\u003e \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eCNE\u003c/span\u003e: FT-IR (ATR, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e): 3374; 2925; 2854; 1588; 1455; 1352; 1272; 1229; 1154; 1072; 998; 943; 872; 826; 779; 749; 724; 694; 637; 596; 562. NMR \u003csup\u003e1\u003c/sup\u003eH (300 MHz, CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): δ 7.13 (t); 6.72 (d); 6.68 (d); 5.89 (m); 5.16 (m); 3.17 (m); 2.95 (m); 2.55 (t); 1.79 (m); 1.59 (m); 1.30 (m); 0.90 (m). NMR \u003csup\u003e13\u003c/sup\u003eC (300 MHz, CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): δ 155.98; 144.97; 129.45; 120.83; 117.57; 115.55; 112.76; 57.66; 35.86; 31.16; 29.80; 27.90; 26.94; 26.66; 22.66; 14.08.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eCTMA\u003c/span\u003e: FTIR (ATR, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e): 2926; 2855; 1736; 1637; 1587; 1451; 1378; 1294; 1233; 1148; 1121; 1002; 941; 807; 780; 723; 693; 647. NMR \u003csup\u003e1\u003c/sup\u003eH (300 MHz, CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): δ 7.20; 7.04 (d); 6.94 (d); 6.34 (d); 5.74 (d); 5.16 (m); 2.61 (t); 2.07 (s); 1.97 (t); 1.63 (m); 1.54 (m); 1.31 (m); 0.90 (m). NMR \u003csup\u003e13\u003c/sup\u003eC (300 MHz, CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): δ 166.01; 151.09; 144.44; 136.16; 132.36; 128.84; 126.88; 125.66; 121.30; 118.70; 115.55; 112.35; 72.65; 57.14; 35.60. 30.98; 29.54; 27.72; 25.44; 22.42; 18.20; 13.88.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the FT-IR spectra (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), the stretch of the C-H sp\u003csup\u003e2\u003c/sup\u003e (aliphatic) bond at 3009 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is only observed in CN. The stretch of the C-O-C (oxirane ring) bond at 826 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is presented in CNE, demonstrating the successful epoxidation. In the FT-IR spectrum of CTMA, the stretching bands at 826 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and at 3300 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, characteristic of the O-H bond of the phenol, disappeared, and an absorption band was detected at 1736 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, corresponding to the bond C\u0026thinsp;=\u0026thinsp;O (carbonyl from methacrylate).\u003c/p\u003e \u003cp\u003eRelative to \u003csup\u003e1\u003c/sup\u003eH NMR and \u003csup\u003e13\u003c/sup\u003eC NMR spectra, CN showed a signal at the range of δ 5.37\u0026ndash;5.43 ppm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea - dotted rectangle 1) relative to the olefinics hydrogens of the lateral chain, that was absent in CNE and CTMA. The signal at the range of δ 2.75\u0026ndash;3.17 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea - dotted rectangle 2) is attributed to the oxirane ring of CNE, also confirmed by the signal at 57.66 ppm in the \u003csup\u003e13\u003c/sup\u003eC NMR (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb \u0026ndash; dotted rectangle 2), which has practically disappeared in CTMA spectra. Between δ 5.74\u0026ndash;6.34 ppm, signals corresponding to the vinylic hydrogens (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea - dotted rectangle 4) were observed, along with a singlet at δ 2.07 ppm attributed to the methyl protons of the methacrylate group of CTMA (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea \u0026ndash; dotted rectangle 3). The \u003csup\u003e13\u003c/sup\u003eC NMR confirmed the presence of the methacrylate group in CTMA showing the terminal methyl group at δ 18.20 ppm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb \u0026ndash; dotted rectangle 3) and the signal at the range of 166 ppm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb \u0026ndash; dotted rectangle 5), characteristic of the carbonyl (C\u0026thinsp;=\u0026thinsp;O). Also, the signal at the range of 72.65 ppm is characteristic of the C-O-C bonds of the methacrylate group (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb \u0026ndash; dotted rectangle 6).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Degree of conversion\u003c/h2\u003e \u003cp\u003eThe degree of conversion results (means and standard deviations) are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, which indicates that there was no statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.052) found among the groups regarding the degree of conversion data.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Water sorption and solubility\u003c/h2\u003e \u003cp\u003eThe outcomes of water sorption and solubility of the experimental resin composites are summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The CTMA-40 and CTMA-50 groups showed significantly lower water sorption results compared to the control group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Furthermore, the incorporation of CTMA (10, 20, 40 and 50%) into composites significantly reduced the solubility when compared to Bis-GMA-based composite (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Viscosity\u003c/h2\u003e \u003cp\u003eThe viscosity of the filler-free resins exhibited a linear a linear relationship with increasing shear rate, suggesting Newtonian behavior for all resins. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents the viscosity outcomes measured at 500 s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e shear rate. All of the CTMA groups obtained significantly lower viscosities compared to the control, and the incorporation of CTMA gradually reduced the viscosity of the experimental resins (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMean values\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) of viscosity for each group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposites\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean viscosity (SD) (cP \u003csup\u003ea\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep-value (\u0026lt;\u0026thinsp;0.001)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e251.83 (0.50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e184.62 (0.55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e155.24 (1.35)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e133.67(0.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e123.99(0.29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eE\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003e cP: centipoise\u0026thinsp;=\u0026thinsp;0.01 P.\u003c/p\u003e \u003cp\u003eDifferent capital letters present statistically significant difference among the viscosities\u003c/p\u003e \u003cp\u003eof the groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Thermogravimetric analysis\u003c/h2\u003e \u003cp\u003eThe TGA thermograms demonstrate that all samples were in general stable up to 200 \u0026ordm;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe degradation characteristic temperatures were summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, including the initial decomposition temperature (T\u003csub\u003ed5%\u003c/sub\u003e), representing 5% weight loss) and the temperature corresponding to the maximum decomposition rate (T\u003csub\u003emax\u003c/sub\u003e). The addition of a maximum of 20% CTMA (CTMA-10 and CTMA-20) to resins slightly increased the initial thermal degradation temperature, thereby enhancing the thermal degradation stability of the composites compared to the control. Conversely, the addition of higher concentrations of CTMA (CTMA-40 and CTMA-50) led to a decrease of the initial thermal degradation temperature.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermogravimetric analysis (TGA) results\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposites\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eT\u003csub\u003em\u0026aacute;x\u003c/sub\u003e \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT\u003csub\u003ed5%\u003c/sub\u003e \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e418 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e286 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e422 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e295 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e423 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e294 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e427 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e247 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e427 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e259 \u0026ordm;C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003e T\u003csub\u003em\u0026aacute;x\u003c/sub\u003e: maximum decomposition. \u003csup\u003eb\u003c/sup\u003e T\u003csub\u003ed5%\u003c/sub\u003e: 5% decomposition.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Dynamic mechanical analysis\u003c/h2\u003e \u003cp\u003eThe storage modulus for all groups decreased with rising temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea). The control composite obtained the highest value of storage modulus at the rubbery zone (180 \u0026ordm;C), which decreased slightly with increasing CTMA content. At 37 \u0026ordm;C, the CTMA-20 resin exhibited the highest storage modulus (840.42 MPa) among the CTMA-based resins (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The progressive addition of CTMA resulted in a decline in T\u003csub\u003eg\u003c/sub\u003e (determined as the maximum of the tan δ versus temperature) in comparison to the control (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). When CTMA was used as a comonomer, all resin composites showed higher tan δ peaks than the control, especially for CTMA-40 and CTMA-50 (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb). Also, regarding the width of tan δ peaks, the samples revealed similar wide peaks.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDynamic mechanical analysis (DMA) results\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposites\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStorage modulus at 37 \u0026ordm;C (MPa \u003csup\u003ea\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStorage modulus at 180 \u0026ordm;C (MPa \u003csup\u003ea\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTg (\u0026ordm;C)\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e981.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e31.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e141\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e738.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e128.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e840.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e700.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e119.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTMA-50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e786.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e115.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003e MPa: megapascal. \u003csup\u003eb\u003c/sup\u003e Glass transitions temperatures were determined as the maximum of the tan δ versus temperature.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Flexural strength and elastic modulus\u003c/h2\u003e \u003cp\u003eThe outcomes of the flexural strength (FS) and elastic modulus (E) are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. All composites formulated with CTMA showed FS and E similar to the control (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The CTMA-20 material achieved the E highest values, which was statistically significant different from CTMA-40 composite (p\u0026thinsp;=\u0026thinsp;0.028).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe present investigation revealed that the first and second hypothesis must be accepted, once the physicochemical properties tested were not negatively affected by the addition of CTMA and there was a reduction in the viscosity, water sorption and solubility in comparison with BisGMA-based resin by the addition of the novel trimethacrylate monomer. Also, CTMA groups attained mechanical properties similar to traditional systems based on Bis-GMA. Consequently, third hypothesis should be accepted.\u003c/p\u003e \u003cp\u003eAn effective polymerization plays a very important role on the physicochemical and mechanical properties of resin-based dental materials. Double bond conversion of multi-methacrylate polymers is rarely complete because of the flexibility of monomers during propagation, and due to the limited mobility of partially cured macromolecules as the reaction progresses [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The long flexible carbon chain of CTMA probably induced a delayed gelation, increasing the mobility of the active species after the formation of microgels during polymerization and achieving a similar degree of conversion as the traditional Bis-GMA/TEGDMA control resin.\u003c/p\u003e \u003cp\u003eThe long aliphatic carbon chain of CTMA, devoid of polar hydroxyls, also contributes to its high hydrophobicity [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], thus explaining why CTMA groups showed lower water sorption. This may have led to smaller amounts of leachable monomers from CTMA composites, and overall soluble products, along with the acceptable degree of conversion. In contrast to CTMA, the BisGMA-rich composites may be partially degraded into BPA when they are in contact with human saliva [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and might contaminate the body.\u003c/p\u003e \u003cp\u003eApart from reduced water sorption and solubility, a relatively low viscosity is desired for monomers employed in resin-based dental materials, in order to facilitate handling and incorporation of filler particles. The Bis-GMA content reduces side-chain mobility, as it increases the formation of strong hydrogen bonds through its hydroxyls [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The observed decrease in viscosity was attributed to the substitution of the viscous Bis-GMA by CTMA, since the latter has a high molecular weight but a long flexible carbon chain free of hydroxyl groups, thereby not forming hydrogen bonds which increase viscosity. This assertion finds validation in CTMA-50 group, which eliminated all content of Bis-GMA and the consequent formation of hydrogen bonds, resulting in a substantial reduction in the viscosity of the composites.\u003c/p\u003e \u003cp\u003eIn terms of thermal degradation stability, the incorporation of CTMA in composites up to 20% was able to improve it, which could be attributed to the bulky aromatic structure and long side alkyl chains of CTMA. These characteristics may have prevented the packing of the polymer chains leading to an increase in the voids in the system. Also, all groups were stable up to 200 \u0026ordm;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e), indicating a similar and acceptable thermal stability of resin composites for safe use in the oral cavity. The survey of Jaillet et al. (2014) investigated the thermal degradation of novel vinylester prepolymers from cardanol in comparison to diglycidyl ether of bisphenol A (DGEBA), which showed similar thermal stability [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. A maximum decomposition rate around 430\u0026deg;C for cardanol-based resins was found, quite similar to the values obtained for CTMA-based resin composites (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; T\u003csub\u003em\u0026aacute;x\u003c/sub\u003e: 422 to 427\u0026deg;C).\u003c/p\u003e \u003cp\u003eConcerning mechanical properties, dynamic mechanical analysis provides information about the properties of polymer networks, such as storage modulus and glass transition temperature (T\u003csub\u003eg\u003c/sub\u003e), by evaluating the structure and stiffness of the materials [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Control composite obtained the highest value of storage modulus at the rubbery zone (180 \u0026ordm;C), indicating greater entanglement of polymer networks. Crosslinking density is an important variable in the viscoelastic behavior of the polymers, and, typically, resin-based materials with multimethacrylates are highly crosslinked polymer networks, once a higher number of functionalities is beneficial for the storage modulus in the rubbery zone [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, our results showed that the trimethacrylate addition reduced the storage modulus, and, therefore, the crosslinking density of the composites. Furthermore, the incorporation of CTMA revealed a plasticizing effect on Bis-GMA composites, preventing close packing between the polymer backbones, as seen in the lowering of T\u003csub\u003eg\u003c/sub\u003e in comparison to the control (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). However, the T\u003csub\u003eg\u003c/sub\u003e obtained by CTMA composites are still above body temperature and food/beverage consumed (\u0026gt;\u0026thinsp;115 \u0026ordm;C); therefore, their physical and mechanical properties are preserved, ensuring optimal intraoral performance of these materials.\u003c/p\u003e \u003cp\u003eThe height of the maximum tan δ peak on DMA reflects the extent of mobility of the polymer chain segments as a function of temperature. When CTMA was used as a comonomer, all composites showed higher tan δ peaks than the control. This result reveals a high mobility of the CTMA polymer networks (especially for CTMA-40 and CTMA-50) due to the flexible long carbon chain, causing an increase in the viscous behavior (less energy is stored in the material) at the expense of the elastic component. Also, regarding the width of tan δ peaks, the samples revealed similar wide peaks, which means that the glass transition occurs over a wide temperature range. This wide glass transition is apparently related to the chain-growth polymerization in heterogeneous networks and usually occurs with increasing crosslink density of the polymer network [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOne of the few properties correlated with the clinical performance of resin composite restorations is the flexural strength, as this in vitro test is correlated to the clinical wear and tensions undergone in restorations and plays an important role in the acceptance of restorative materials [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The statistical analysis demonstrated similarity of mechanical properties of CTMA-based composites when compared to control. The main reason that could explain this behavior is the CTMA chemical structure, which has one aromatic ring that confer high mechanical stability to the material similar to the rigid backbone bisphenol-A structure of the Bis-GMA monomer. The similar degree of conversion outcomes may also correlate to the results obtained for flexural strength and elastic modulus, since physical and mechanical properties of resin-based composites are influenced by the degree of polymerization [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. As Bis-GMA based resin composites have decades of clinical success and currently still are standard composites employed around the world. The proposed newly synthesized monomer CTMA then achieved similar or superior physicochemical properties to the control Bis-GMA, proving the clinical suitability, with the advantages of lacking bisphenol-A as well as CTMA-synthesis thresholds from a plant-derived compound, thereby turning this a monomer derived from a renewable source.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn summary, this research is the first to exhibit the synthesis of a CNSL-derived trimethacrylate monomer and its possible application in resin-based dental materials. Incorporation of CTMA into resin composites reduced its viscosity, water sorption and solubility without interfering in flexural strength and polymerization when compared to Bis-GMA-based material. Within the limitation of this study, CTMA is a feasible co-monomer for dental restorative materials, as a Bis-GMA substitute.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConflict of Interest:\u003c/strong\u003e \u003cp\u003eAuthors Madiana Magalh\u0026atilde;es Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled \u0026ldquo;synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid\u0026rdquo;, which includes the CTMA monomer used in this study.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003cp\u003eAuthors Madiana Magalh\u0026atilde;es Moreira, Rita de Cassia Sousa Pereira, Lucas Renan Rocha da Silva, Victor Pinheiro Feitosa and Diego Lomonaco have deposited a patent at the National Institute of Industrial Property (INPI) of Brazil, entitled \u0026ldquo;synthesis and dental application of functional methacrylic monomers derived from cashew nut shell liquid\u0026rdquo;, which includes the CTMA monomer used in this study.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis study was funded by National Counsel of Technological and Scientific Development (CNPq - Brazil), by Coordination for the Improvement of Higher Education Personnel (CAPES - Brazil) and by Cearense Foundation for Scientific and Technological Development Support (FUNCAP \u0026ndash; Cear\u0026aacute;, Brazil).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Moreira, M.M.; Silva, A.L.; Pereira, R.C.S.; and Rocha da Silva, L.R. Moreira, M.M. prepared figures 1, 4, 5, and 8; Rocha da Silva, L.R. prepared figures 2 and 3; Pereira, R.C.S. prepared figure 6; and Lomonaco, D. prepared figure 7. The first draft of the manuscript was written by Moreira, M.M., and all authors critically revised the manuscript for important intellectual content. Supervision was provided by Lomonaco D. and Feitosa V.P. All authors have read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe authors affirm that the data supporting the results of this investigation are included in the manuscript. If any raw data files are required in a different format, they can be obtained from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eStansbury JW (2012) Dimethacrylate network formation and polymer property evolution as determined by the selection of monomers and curing conditions. Dent Mater 28(1):13\u0026ndash;22. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.dental.2011.09.005\u003c/span\u003e\u003cspan address=\"10.1016/j.dental.2011.09.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSzczesio-Wlodarczyk A, Polikowski A, Krasowski M, Fronczek M, Sokolowski J, Bociong K (2022) The Influence of Low-Molecular-Weight Monomers (TEGDMA, HDDMA, HEMA) on the Properties of Selected Matrices and Composites Based on Bis-GMA and UDMA. 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J Mech Phys Solids 112:25\u0026ndash;49. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmps.2017.11.018\u003c/span\u003e\u003cspan address=\"10.1016/j.jmps.2017.11.018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Cardanol. Methacrylates. Composite resins. Physicochemical properties. Flexural strength. Dynamic mechanical property","lastPublishedDoi":"10.21203/rs.3.rs-4648523/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4648523/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eTo analyze the incorporation of cardanol trimethacrylate monomer (CTMA), derived from the cashew nut shell liquid, as a substitute for Bis-GMA on the physicochemical and mechanical properties of experimental resin composites.\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eThe intermediary cardanol epoxy was synthesized via cardanol epoxidation, followed by synthesis of CTMA through methacrylic anhydride solvent-free esterification. Experimental resin composites were formulated with an organic matrix composed of Bis-GMA/TEGDMA (50/50 wt %) (control). CTMA was gradually added to replace different proportions of Bis-GMA: 10 wt % (CTMA-10), 20 wt % (CTMA-20), 40 wt % (CTMA-40), and 50 wt % (CTMA-50). The composites were characterized in terms of degree of conversion, water sorption and solubility, viscosity, thermogravimetric analysis, dynamic mechanical analysis, flexural strength and elastic modulus. Data were analyzed with one-way ANOVA and Tukey's post-hoc test (α\u0026thinsp;=\u0026thinsp;0.05), except for water sorption data, which were analyzed by Kruskall-Wallis and Dunn\u0026rsquo;s method.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eCTMA-based and control composites did not show statistically significant differences regarding degree of conversion, flexural strength and elastic modulus. CTMA reduced the viscosity and solubility compared to Bis-GMA-based composite. The CTMA-40 and CTMA-50 exhibited significantly lower water sorption compared to the control. Also, acceptable thermal stability and viscoelastic properties were obtained for safe use in the oral cavity.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe incorporation of CTMA into composites resulted in similar chemical and mechanical properties when compared to Bis-GMA-based material, while reducing viscosity, water sorption and solubility.\u003c/p\u003e\u003ch2\u003eClinical Relevance\u003c/h2\u003e \u003cp\u003eCTMA could be used as a trimethacrylate monomer replacing Bis-GMA in resin composites, thereby minimizing BPA exposure.\u003c/p\u003e","manuscriptTitle":"Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-22 18:36:05","doi":"10.21203/rs.3.rs-4648523/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-07-17T10:45:54+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-17T00:45:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-15T05:56:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"112516909936634702833110137256309660789","date":"2024-07-12T07:40:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"117465765450678574433309175440737620622","date":"2024-07-04T13:32:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-04T13:08:58+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-28T08:25:01+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-06-28T08:24:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"Clinical Oral Investigations","date":"2024-06-27T12:24:04+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"207175dc-d758-4bc9-97ef-ce7f54a46134","owner":[],"postedDate":"July 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-14T16:03:31+00:00","versionOfRecord":{"articleIdentity":"rs-4648523","link":"https://doi.org/10.1007/s00784-024-05959-x","journal":{"identity":"clinical-oral-investigations","isVorOnly":false,"title":"Clinical Oral Investigations"},"publishedOn":"2024-10-08 15:58:01","publishedOnDateReadable":"October 8th, 2024"},"versionCreatedAt":"2024-07-22 18:36:05","video":"","vorDoi":"10.1007/s00784-024-05959-x","vorDoiUrl":"https://doi.org/10.1007/s00784-024-05959-x","workflowStages":[]},"version":"v1","identity":"rs-4648523","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4648523","identity":"rs-4648523","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}