Highlights • Replacing barium glass by DCPD did not affect composite degree of conversion. • Replacing barium glass by DCPD reduced 24-h strength, but not elastic modulus. • At 28 days, strength and ...modulus reductions were more severe in the presence of DCPD. • DCPD increased KIc after 24 h, but caused a reduction after 28 days. • Calcium release was not affected by DCPD content. HPO42− was marginally affected.
Abstract Objective To evaluate the strength and ion release of experimental composites containing TEGDMA-functionalized calcium phosphate particles. Methods Seven composites containing equal parts ...(in mols) of BisGMA and TEGDMA and 60 vol% of fillers were manipulated. Filler phase was constituted by silanized barium glass and 0% (control), 10% or 20% (volume) of dicalcium phosphate dihydrate (DPCD) particles, either non-functionalized or functionalized with two different TEDGMA contents. DCPD particles were synthesized and characterized by X-ray diffraction (XRD), elemental analysis, surface area and dynamic light scattering. Composites were tested for degree of conversion (DC) by near-FTIR. Biaxial flexural strength (BFS) was determined after 24 h and 28 days in water. Calcium and phosphate release after 7 days was assessed using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey test (alpha:5%). Results XRD confirmed the crystalline structure corresponding to DCPD. Elemental analysis revealed particles with zero, 14% or 22% TEGDMA, with similar D50 (around 19 μm) and surface areas from 3.5 to 11.4 m2 /g. The presence of DCPD did not reduce DC. After 24 h, functionalization (both 14% and 22% TEGDMA) improved composite strength in comparison to non-functionalized DCPD, both at 10% and 20% levels. After 28 days, BFS of materials containing 10% functionalized DCPD were statistically similar to the control containing only barium glass. Among composites containing 10% DCPD, particle functionalization with 14% TEGDMA did not jeopardize ion release. Significance At 10 vol%, the use of TEGDMA-functionalized CaP particles improved composite strength in relation to non-functionalized particles, while maintaining similar ion release levels.
This study evaluated the efficacy of experimental TEGDMA-functionalized dicalcium phosphate dihydrate (T-DCPD) filler-based resin-based composites (RBC) in preventing caries lesions around the ...restoration margins (secondary caries, SC). Standardized Class-II cavities were made in sound molars with the cervical margin in dentin. Cavities were filled with a commercial resin-modified glass-ionomer cement (RMGIC) or experimental RBCs containing a bisGMA-TEGDMA resin blend and one of the following inorganic fractions: 60 wt.% Ba glass (RBC-0); 40 wt.% Ba glass and 20 wt.% T-DCPD (RBC-20); or 20 wt.% Ba glass and 40 wt.% T-DCPD (RBC-40). An open-system bioreactor produced Streptococcus mutans biofilm-driven SC. Specimens were scanned using micro-CT to evaluate demineralization depths. Scanning electron microscopy and energy-dispersive X-ray spectroscopy characterized the specimen surfaces, and antimicrobial activity, buffering effect, and ion uptake by the biofilms were also evaluated. ANOVA and Tukey’s tests were applied at p < 0.05. RBC-0 and RBC-20 showed SC development in dentin, while RBC-40 and RMGIC significantly reduced the lesion depth at the restoration margin (p < 0.0001). Initial enamel demineralization could be observed only around the RBC-0 and RBC-20 restorations. Direct antibiofilm activity can explain SC reduction by RMGIC, whereas a buffering effect on the acidogenicity of biofilm can explain the behavior of RBC-40. Experimental RBC with CaP-releasing functionalized T-DCPD filler could prevent SC with the same efficacy as F-releasing materials.
This study describes the synthesis of brushite nanoparticles (CaHPO4·2H2O) functionalized with triethylene glycol dimethacrylate (TEGDMA) and their application in dental restorative composites with ...remineralizing capabilities.
Nanoparticles were synthesized, with TEGDMA being added to one of the precursor solutions at three different molar ratios (0:1, 0.5:1 and 1:1, in relation to the ammonium phosphate precursor). Then, they were added (10 vol%) to a photocurable dimethacrylate matrix containing 50 vol% of reinforcing glass particles. The resulting composites were tested for degree of conversion, biaxial flexural strength and elastic modulus (after 24h and 28days in water), and ion release (over a 28-day period). Commercial composites (one microhybrid and one microfilled) were tested as controls.
The final TEGDMA content in the functionalizing layer was modulated by the molar ratio added to the precursor solution. Functionalization reduced nanoparticle size, but did not reduce agglomeration. Improved mechanical properties were found for the composite containing nanoparticles with higher TEGDMA level in comparison to the composite containing non-functionalized nanoparticles or those with a low TEGDMA level. All brushite composites presented statistically significant reductions in strength after 28 days in water, but only the material with high-TEGDMA nanoparticles retained strength similar to the microhybrid commercial control. Overall, ion release was not affected by functionalization and presented steady levels for 28 days.
Though agglomeration was not reduced by functionalization, the improvement in the matrix-nanoparticle interface allowed for a stronger material, without compromising its remineralizing potential.
To assess the effect of dicalcium phosphate dihydrate (DCPD) or mineral trioxide aggregate (MTA) particles on the microtensile bond strength (μTBS), micro-permeability and enzymatic activity at the ...adhesive-dentin interface of experimental dental adhesives.
An experimental ethanol-based, two-step etch-and-rinse adhesive system was prepared. Four experimental groups were tested, based on the type of particle added: (1) DCPD functionalized with diethylene glycol dimethacrylate (DCPD_DEGDMA), (2) citric acid (DCPD_CA), (3) calcium silicate (MTA) and (4) unfilled (control). All particles were added at 10 wt%. Human third molars had their occlusal enamel removed and dentin surface polished. After acid etching, the adhesives were applied on the dentin surfaces and the teeth were restored with a commercial nanofilled resin composite. The μTBS and micro-permeability were tested after 24 h or 2 months of storage in simulated body fluid (SBF) at 37 °C. Bonded interfaces were observed using scanning electron microcopy (SEM). Gelatinolytic activity at the adhesive interfaces was assessed by in situ zymography at 24 h and 2 months in SBF/37 °C. The results were described as relative florescent units (RFU). μTBS data were analyzed by ANOVA/Games–Howell test. Data from micro-permeability and in situ zymography were analyzed by Kruskal–Wallis/Mann–Whitney test (alpha: 5%).
Differences in μTBS were found among adhesives (control = MTA > DCPD_CA > DCPD_DEGDMA, p < 0.001), but not between storage times. The control group showed the lowest permeability at both observation periods. Except for DCPD_CA, no significant increases in micro-permeability were observed after 2 months. All groups presented significant reductions in RFU values between 24 h and 2 months. DCPD_DEGDMA (at 24 h) and MTA (at 2 months) presented statistically lower RFU than the control (p < 0.01).
Evidence of reduced MMP activity was observed at adhesive interfaces with the use of experimental adhesives containing calcium-releasing particles. However, after two months, bond strength and micro-permeability results suggest that interfacial stability was not affected by adhesive formulation.
to verify the effect of the addition of dicalcium phosphate dihydrate (DCPD) particles functionalized with di- or triethylene glycol dimethacrylate (DEGDMA or TEGDMA) on the degree of conversion ...(DC), post-gel shrinkage (PS), mechanical properties, and ion release of experimental composites.
Four composites were prepared containing a BisGMA/TEGDMA matrix and 60 vol% of fillers. The positive control contained only barium glass fillers, while in the other composites 15 vol% of the barium was replaced by DCPD. Besides the functionalized particles, non-functionalized DCPD was also tested. DC after 24 h (n = 3) was determined by FTIR spectroscopy. The strain gage method was used to obtain PS 5 min after photoactivation (n = 5). Flexural strength and modulus (n = 10) were calculated based on the biaxial flexural test results, after specimen storage for 24 h or 60 days in water. The same storage times were used for fracture toughness testing (FT, n = 10). Calcium and phosphate release up to 60 days was quantified by ICP-OES (n = 3). Data were analyzed by ANOVA/Tukey test (alpha: 5%).
Composites containing functionalized DCPD presented higher DC than the control (p < 0.001). The material containing DEGDMA-functionalized particles showed higher PS than the other composites (p < 0.001). After 60 days, only the composite with DEGDMA-functionalized DCPD presented fracture strength similar to the control, while for flexural modulus only the composite with TEGDMA-functionalized particles was lower than the control (p < 0.001). FT of all composites containing DCPD was higher than the control after 60 days (p < 0.005). Calcium release was higher for the composite with non-functionalized DCPD at 15 days and no significant reductions were observed for composites with functionalized DCPD during the observation period (p < 0.001). For all the tested composites, phosphate release was higher at 15 days than in the subsequent periods, and no difference among them was recorded at 45 and 60 days (p < 0.001).
DCPD functionalization affected all the studied variables. The composite with DEGDMA-functionalized particles was the only material with strength similar to the control after 60 days in water; however, it also presented the highest shrinkage. The presence of DCPD improved FT, regardless of functionalization. DCPD functionalization reduced ion release only during the first 15 days.
•The organic content of functionalized DCPD particles increased composite degree of conversion and volumetric shrinkage.•The composite containing DCPD particles functionalized with DEGDMA presented strength similar to the control after 60 days.•Composite fracture toughness increased with the replacement of part of the silanized glass by DCPD particles (0.75 glass : 0.25 DCPD).•Composites containing 15 vol% DCPD showed calcium release levels above 1 ppm after 60 days.•DCPD functionalization reduced calcium release only after the first two weeks.
Display omitted
To compare the effects of replacing reinforcing barium glass particles by DCPD (dicalcium phosphate dihydrate), as opposed to simply reducing glass filler content, on composite flexural properties ...and degree of conversion (DC). On a second set of experiments, composites with different “DCPD: glass” ratios were exposed to prolonged water immersion to verify if the presence of DCPD particles increased hydrolytic degradation. Methods: Two series of composites were prepared: 1) composites with total inorganic content of 50 vol% and “DCPD: glass” ratios ranging from zero (glass only) to 1.0 (DCPD only), in 0.25 increments, and 2) composites containing only silanized glass (from zero to 50 vol%). Disk-shaped specimens were fractured under biaxial flexural loading after 24 h in water. Another set of specimens of composites with different “DCPD: glass” ratios was stored in water for 24 h, 30, 60, 90 and 120 days and tested in flexure. DC was determined using FTIR spectroscopy. Data were analyzed using Kruskal-Wallis/Dunn test (flexural properties) or ANOVA/Tukey test (DC, alpha: 0.05). Results: For glass-only composites, reducing inorganic content caused a linear decrease in strength. The presence of DCPD did not affect composite strength up until a “DCPD: glass” ratio of 0.5. On the other hand, materials with 0.75 and 1.0 DCPD showed significantly lower strength than the glass-only composite with 12.5 vol% filler and the unfilled resin, respectively (p < 0.001). Except for the 0.25 DCPD composite, the presence of DCPD did not contribute to increase flexural modulus. After water storage, composites containing DCPD showed higher percent reductions in properties than the control, but only in a few cases the effect was statistically significant (strength: 0.5 DCPD, modulus: 0.25 and 1.0 DCPD). DC was only marginally affected by DCPD fraction. Significance: For composites with “DCPD: glass” of 0.25 and 0.5, reductions in strength were related to the lower glass content, and not due to the presence of DCPD. Flexural modulus was primarily defined by glass content. Overall, composites containing DCPD particles presented higher reductions in properties after water storage, but it remained within limits reported for commercial materials.
To evaluate experimental dimethacrylate-based materials containing calcium orthophosphates or calcium silicate particles in terms of their optical, mechanical and Ca2+ release behaviour.
Dicalcium ...phosphate dihydrate (DCPD), hydroxyapatite (HAp), beta-tricalcium phosphate (β-TCP) or calcium silicate (CaSi) particles were added to a photocurable BisGMA/TEGDMA resin (1:1 in mols) at a 30 vol% fraction. Materials containing silanized or non-silanized barium glass particles were used as controls. Degree of conversion (DC) at the top and base of 2-mm thick specimens was determined by ATR-FTIR spectroscopy (n = 5). Translucency parameter (TP) and transmittance (%T) were determined using a spectrophotometer (n = 3). Biaxial flexural strength (BFS) and flexural modulus (FM) were determined by biaxial flexural testing after 24 h storage in water (n = 10). Ca2+ release in water was determined during 28 days by inductively coupled plasma optical emission spectrometry (n = 3). Statistical analysis was performed using ANOVA/Tukey test (DC: two-way; TP, %T; BFS and FM: one-way; Ca2+ release: repeated measures two-way, α = 5 %). Results: CaSi and β-TCP particles drastically reduced DC at 2 mm, TP and %T (p < 0.001). Compared to both controls, all Ca2+-releasing materials presented lower BFS (p < 0.001) and only the material with DCPD showed significantly lower FM (p < 0.05). The material containing CaSi presented the highest Ca2+ release, while among materials formulated with calcium orthophosphates the use of DCPD resulted in the highest release (p < 0.001).
CaSi particles allowed the highest Ca2+ release. Notwithstanding, the use of DCPD resulted in a material with the best compromise between optical behaviour, DC, strength and Ca2+ release.
•The addition of β-TCP and CaSi reduced degree of conversion, %T and translucency.•All particles negatively affected biaxial flexural strength.•The addition of DCPD reduced the flexural modulus in relation to the control.•The addition CaSi resulted in the greater release of Ca2+.
To synthesize and characterize brushite particles in the presence of acidic monomers (acrylic acid/AA, citric acid/CA, and methacryloyloxyethyl phosphate/MOEP) and evaluate the effect of these ...particles on degree of conversion (DC), flexural strength/modulus (FS/FM) and ion release of experimental composites.
Particles were synthesized by co-precipitation with monomers added to the phosphate precursor solution and characterized for monomer content, size and morphology. Composites containing 20 vol% brushite and 40 vol% reinforcing glass were tested for DC, FS and FM (after 24 h and 60 d in water), and 60-day ion release. Data were subjected to ANOVA/Tukey tests (DC) or Kruskal–Wallis/Dunn tests (FS and FM, alpha: 5%).
The presence of acidic monomers affected particle morphology. Monomer content on the particles was low (0.1–1.4% by mass). Composites presented similar DC. For FS/24 h, only the composite containing DCPD_AA was statistically similar to the composite containing 60 vol% of reinforcing glass (without brushite, “control”). After 60 days, all brushite-containing materials showed similar FS, statistically lower than the control composite (p<0.01). Composites containing DCPD_AA, DCPD_MOEP or DCPD_U (“unmodified”) showed statistically similar FM/24 h, higher than the control composite. After prolonged immersion, all composites were similar to the control composite, except DCPD_AA. Cumulative ion release ranged from 21 ppm to 28 ppm (calcium) and 9 ppm to 17 ppm (phosphate). Statistically significant reductions in ion release between 15 and 60 days were detected only for the composite containing DCPD_MOEP.
Acidic monomers added to the synthesis affected brushite particle morphology. After 60-day storage in water, composite strength was similar among all brushite-containing composites. Ion release was sustained for 60 days and it was not affected by particle morphology.
•The presence of acidic monomers in the synthesis affected DCPD particle morphology.•Monomer retention on particles was low.•DCPD morphology did not influence composite strength after aging.•Overall, composite modulus was not compromised by DCPD after aging.•At 60 days, ion release was higher for the composite with the smallest particles.
The aim of this study was to evaluate the effect of an adhesive loaded with 0.2% cooper (Cu) and 5% zinc oxide (ZnO) nanoparticles (Nps) on its adhesive properties and enzymatic activity at the ...hybrid layer ex vivo in a randomized clinical model.OBJECTIVEThe aim of this study was to evaluate the effect of an adhesive loaded with 0.2% cooper (Cu) and 5% zinc oxide (ZnO) nanoparticles (Nps) on its adhesive properties and enzymatic activity at the hybrid layer ex vivo in a randomized clinical model.Fifteen patients participated in this study, and a total of 30 third molars were used. Occlusal cavities (4 × 4 × 2 mm) were made in each tooth, and randomly divided into 2 groups: (i) Experimental group: commercial adhesive loaded with 0.2wt% CuNps and 5wt% ZnONps; and (ii) Control Group: non-loaded commercial adhesive. Teeth were restored with resin composite. Thirty days later, extractions were performed. Extracted teeth were longitudinally sectioned. Nps in powder were characterized by field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray (EDX) analysis. Microtensile bond strength (μTBS), degree of conversion (DC), and nanoleakeage (NL) tests were executed. In situ zymography (Zym) was performed to evaluate the gelatinolytic activity at the hybrid layer. Student's t-test (α = 0.05) was applied for all tests.METHODSFifteen patients participated in this study, and a total of 30 third molars were used. Occlusal cavities (4 × 4 × 2 mm) were made in each tooth, and randomly divided into 2 groups: (i) Experimental group: commercial adhesive loaded with 0.2wt% CuNps and 5wt% ZnONps; and (ii) Control Group: non-loaded commercial adhesive. Teeth were restored with resin composite. Thirty days later, extractions were performed. Extracted teeth were longitudinally sectioned. Nps in powder were characterized by field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray (EDX) analysis. Microtensile bond strength (μTBS), degree of conversion (DC), and nanoleakeage (NL) tests were executed. In situ zymography (Zym) was performed to evaluate the gelatinolytic activity at the hybrid layer. Student's t-test (α = 0.05) was applied for all tests.μTBS and DC did not show significant differences (p > 0.05) between both groups. However, NL and gelatinolytic activity at the hybrid layer showed significant values (p < 0.05) for experimental group in comparison with control group.RESULTSμTBS and DC did not show significant differences (p > 0.05) between both groups. However, NL and gelatinolytic activity at the hybrid layer showed significant values (p < 0.05) for experimental group in comparison with control group.The addition of 0.2% CuNps and 5% ZnONps to a universal adhesive decreases NL and gelatinolytic activity at the hybrid layer, without jeopardizing its adhesive properties.CONCLUSIONThe addition of 0.2% CuNps and 5% ZnONps to a universal adhesive decreases NL and gelatinolytic activity at the hybrid layer, without jeopardizing its adhesive properties.This randomized clinical trial with ex vivo analysis demonstrate that a commercial adhesive modified with 0.2wt% Cu and 5wt% ZnO Nps that does not affect its adhesive properties, reducing gelatinolytic activity and nanoleakage at the hybrid layer, which should contribute to an improvement of long term bonding-dentine clinical performance.SIGNIFICANCEThis randomized clinical trial with ex vivo analysis demonstrate that a commercial adhesive modified with 0.2wt% Cu and 5wt% ZnO Nps that does not affect its adhesive properties, reducing gelatinolytic activity and nanoleakage at the hybrid layer, which should contribute to an improvement of long term bonding-dentine clinical performance.
