- Email: [email protected]
The influence of TiO2 nanoparticles on properties of composite resin
d e n t a l m a t e r i a l s 2 8 S ( 2 0 1 2 ) e1–e70
were measured again. Data were submitted to Proc Mixed and Tukey–Kramer tests (˛ = 0.05). Results: After biodegradation both composite resin showed a significant increase on surface roughness, but the ceramic did not. Concerning surface Knoop hardness, there was no significant effect of biodegradation on esthetical restorative materials. Conclusion: S. mutans biofilm increases the surface roughness of Filtek Z350 and Empress Direct, but did not affect surface Knoop hardness. Ceramic surface was not affected by S. mutans biofilm.
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was superior.
http://dx.doi.org/10.1016/j.dental.2012.07.123 117 Edge chip fracture resistance of restorative materials G.D. Quinn ∗ , A.A. Giuseppetti, K.H. Hoffman, J.B. Quinn Paffenbarger Research Center, American Dental Association Foundation, USA Objectives: Evaluate edge chip resistance of dental restorative materials. Compare results obtained with different indenters. Compare different indices of edge chip resistance. Materials and methods: Bend bar and wear test type test pieces were mounted and polished to have well defined 90◦ edges. The force to pop a chip off was measured as a function of distance from the edge. Sharp conical, Vickers, and Rockwell C indenters were used. Data trends were analyzed with linear and power law functions. Materials included a feldspathic porcelain, leucite and lithium disilicate glass ceramics, a 3YTZP zirconia, a filled resin-matrix composite, a resin denture material, and a nanoceramic filled composite. Various indices of chip resistance such as “edge toughness Te ,” “edge strength, SE (0.5),” and “edge chip resistance, ReA ,” were compared. Results: Edge chip resistance varied significantly with the type of indenter used. In some cases the data was well fit by a simple linear trend, but in other instances, a power law fit
Conclusions: Although a full analysis showing a data trend over a broad range of distances and chipping forces characterizes a material’s chipping resistance, a simple quantitative index of the force necessary to make a chip at a set distance of 0.5 mm as proposed by Watts is adequate for comparative purposes. Chipping resistance correlated strongly with fracture toughness. http://dx.doi.org/10.1016/j.dental.2012.07.124 118 The influence of TiO2 nanoparticles on properties of composite resin A.N.S. Rastelli 1,∗ , A.A. Faria 1 , P.B. Agnelli 2 , M.I.B. Bernardi 3 , P.P.N.S. Garcia 1 , C.W. Souza 2 , V.S. Bagnato 3 1
University Estadual Paulista, UNESP, Brazil Federal University of São Carlos, Brazil 3 University of São Paulo, USP, Brazil 2
Objectives: The resin-based composites result in more plaque accumulation than other materials. The purpose of this study was to evaluate the antimicrobial activity over Streptococcus mutans biofilm formation, Vickers hardness (VHN) and color changes of one universal modified microhybrid composite resin with TiO2 nanoparticles. Materials and methods: TiO2 dispersed in SiO2 nanoparticles were synthesized by a polymeric precursor method using sol-gel technique and were incorporated at 1 or 2% (w/w) using FiltekTM Z250 composite resin (Z, color A2 ). For VHN (n = 15), and for antimicrobial activity (n = 15), the samples were made in a metallic mould (4 mm × or 3 mm × 2 mm), and for color stability (n = 30) (10 mm × 2 mm). The samples were lightcured for 40 s using LED LCU (Celalux, Voco). Four indentations were made on both top (T) and bottom (B) surfaces using
e54
d e n t a l m a t e r i a l s 2 8 S ( 2 0 1 2 ) e1–e70
a Leica VMHT Mot (Germany) (50 gf, 30 s). The antimicrobial effect for different experimental Groups (Z, Z + 1% and Z + 2%) was tested regarding to the total number of Streptococcus mutans (CFU/mL) and direct contact inhibition was observed by scanning electron microscopy (SEM). Color parameters were analyzed in a spectrophotometer Color-guide 45/0, PCB 6807 (Byk Gardner GmbH, Gerestsried, Germany) to evaluate the color changes using CIE L*a*b* measuring system after 24 hs. E* values greater than or equal to 3.3 were considered as a clinically unacceptable color change and can be detected by the naked eye. Data for total number of Streptococcus mutans, VHN and color changes were submitted to one-way analysis of variance (ANOVA) and Tukey’s test at 0.05 significance level. Results: An 64% and 42.7% reduction in bacterial counts was observed with 1 and 2% (w/w) TiO2 containing composites compared with their control without nanoparticles, indicat-
Compound
Structural formula
ACP DCPA TCP
Ca2 P2 O7 ·H2 O CaHPO4 Ca3 (PO4 )2
Surface area (m2 /g)
Materials and methods: Commercial powders were used in the experiment (ACP and TCP from Sigma–Aldrich (St. Louis, MO, USA and DCPA from Synth, Diadema, Brazil). Particle structure (crystalline or amorphous) was characterized by Xray diffraction (XRD Rigaku MultiFlex, Tokyo, Japan). Surface area and particle size were determined using BET method (Quantacrome, 100E, München, Germany). Solutions of the different compounds were prepared with the same calcium concentration (in mols) and titration curves were obtained by adding 0. 01 mol L−1 of HCl (in 100 l increments) until a pH = 4 was reached. From the titration curves, the pH turning points (pH where the volume of added HCl was sufficient to neutralize the Ca2+ in the solution) and buffer bands (pH approximately constant even with addition of small amounts of acid) were obtained. Results: The diffractograms evidenced the ACP amorphous structure, while both DCPA and TCP showed crystalline structures. The other characteristics are shown in the table: Average particle size (nm)
30.9 2.95 3.14
ing a statistically significant suppression of biofilm growth. Microscopy demonstrated continuous biofilm formation for unmodified composite after seven day, but only sparsely distributed biofilms formed mainly on 1% TiO2 -containing composite. The VHN mean values were: ZT: 86.8 (±2.98), B: 83 (±2.01); Z1%T: 82.7 (±2.98), B: 78.3 (±2.55) and Z2%T: 89 (±2.08), B: 86.7 (±2.79). The TiO2 nanoparticles had a significant influence on the top and bottom surfaces, however top surface at 2% (w/w) showed no statistically significant difference. Regarding color changes (E*): Z: 0.625 (±0.41); Z1%: 0.586 (±0.36) and Z2%: 0.724 (±0.36) no statistical significantly differences were observed. Conclusions: The addition of 1 and 2% (w/w) nanoparticles affected VHN mean values, however did not provide significant color changes (E*). The results obtained indicate that 1% (w/w) TiO2 nanoparticles had a strong antibacterial activity. http://dx.doi.org/10.1016/j.dental.2012.07.125 119 Characterization of calcium phosphates used in bioactive composites M.C. Rodrigues 1,∗ , D.N. Souza 1 , T.L.R. Hewer 2 , G.E.S. Brito 3 , R.R. Braga 1 1
School of Dentistry, University of São Paulo, Brazil School of Engineering, University of São Paulo, Brazil 3 Institute of Physics, University of São Paulo, Brazil 2
Objectives: Characterize calcium phosphate compounds most commonly added to experimental dimethacrylate-based composites: amorphous calcium phosphate (ACP), dicalcium phosphate anhydrous (DCPA) and tricalcium phosphate (TCP).
65 371 314
pH turning point 5.52 5.48 5.24
Buffer band
7.1–6.4 and 4.4–4.0 4.5–4.0 6.6–6.0
Though pH turning points were similar, the amount of acid necessary to reach such pH was different (ACP: 3.6 mL, DCPA: 2.3 mL, TCP: 4.0 mL), indicating that TCP released the highest concentration of Ca2+ ions in solution, followed by ACP and DCPA. Conclusions: ACP, DCPA and TCP presented similar pH turning points. However, the amount of acid consumed in the titration suggests that TCP present a higher remineralizing potential. Also, TCP buffer band between 6.6 and 6.0 may offer some protection against severe pH drops (supported by CNPq). http://dx.doi.org/10.1016/j.dental.2012.07.126 120 Illuminant influences colorimetric parameters of resin matrix with varied camphorquinone J.P. Salomon 1,2,∗ , J.L. Ferracane 2 , J.J. Robin 3 , I. Krejci 4 , S. Ardu 4 1
Nancy, France Portland, OR, USA 3 Montpellier, France 4 Geneva, Switzerland 2
Objectives: The aim of the study was to assess the influence of the illuminants on the correlation between the percentage of camphorquinone (CQ) and the colorimetric parameters of a resin matrix for dental composites. Materials and methods: The experimental matrix contains CQ/EDMAB concentrations at 0.125, 0.25, 0.50, 0.75, 1.00, 1.50, 2% (mol.%) in a Bis-GMA/TEGDMA (80/20 wt.%). Ten 1.5 mm thick, disk-shaped samples were prepared for each experimental group by curing under a Mylar strip on both sides in a standard steel mold with a QTH light (Trilight Elipar –
were measured again. Data were submitted to Proc Mixed and Tukey–Kramer tests (˛ = 0.05). Results: After biodegradation both composite resin showed a significant increase on surface roughness, but the ceramic did not. Concerning surface Knoop hardness, there was no significant effect of biodegradation on esthetical restorative materials. Conclusion: S. mutans biofilm increases the surface roughness of Filtek Z350 and Empress Direct, but did not affect surface Knoop hardness. Ceramic surface was not affected by S. mutans biofilm.
e53
was superior.
http://dx.doi.org/10.1016/j.dental.2012.07.123 117 Edge chip fracture resistance of restorative materials G.D. Quinn ∗ , A.A. Giuseppetti, K.H. Hoffman, J.B. Quinn Paffenbarger Research Center, American Dental Association Foundation, USA Objectives: Evaluate edge chip resistance of dental restorative materials. Compare results obtained with different indenters. Compare different indices of edge chip resistance. Materials and methods: Bend bar and wear test type test pieces were mounted and polished to have well defined 90◦ edges. The force to pop a chip off was measured as a function of distance from the edge. Sharp conical, Vickers, and Rockwell C indenters were used. Data trends were analyzed with linear and power law functions. Materials included a feldspathic porcelain, leucite and lithium disilicate glass ceramics, a 3YTZP zirconia, a filled resin-matrix composite, a resin denture material, and a nanoceramic filled composite. Various indices of chip resistance such as “edge toughness Te ,” “edge strength, SE (0.5),” and “edge chip resistance, ReA ,” were compared. Results: Edge chip resistance varied significantly with the type of indenter used. In some cases the data was well fit by a simple linear trend, but in other instances, a power law fit
Conclusions: Although a full analysis showing a data trend over a broad range of distances and chipping forces characterizes a material’s chipping resistance, a simple quantitative index of the force necessary to make a chip at a set distance of 0.5 mm as proposed by Watts is adequate for comparative purposes. Chipping resistance correlated strongly with fracture toughness. http://dx.doi.org/10.1016/j.dental.2012.07.124 118 The influence of TiO2 nanoparticles on properties of composite resin A.N.S. Rastelli 1,∗ , A.A. Faria 1 , P.B. Agnelli 2 , M.I.B. Bernardi 3 , P.P.N.S. Garcia 1 , C.W. Souza 2 , V.S. Bagnato 3 1
University Estadual Paulista, UNESP, Brazil Federal University of São Carlos, Brazil 3 University of São Paulo, USP, Brazil 2
Objectives: The resin-based composites result in more plaque accumulation than other materials. The purpose of this study was to evaluate the antimicrobial activity over Streptococcus mutans biofilm formation, Vickers hardness (VHN) and color changes of one universal modified microhybrid composite resin with TiO2 nanoparticles. Materials and methods: TiO2 dispersed in SiO2 nanoparticles were synthesized by a polymeric precursor method using sol-gel technique and were incorporated at 1 or 2% (w/w) using FiltekTM Z250 composite resin (Z, color A2 ). For VHN (n = 15), and for antimicrobial activity (n = 15), the samples were made in a metallic mould (4 mm × or 3 mm × 2 mm), and for color stability (n = 30) (10 mm × 2 mm). The samples were lightcured for 40 s using LED LCU (Celalux, Voco). Four indentations were made on both top (T) and bottom (B) surfaces using
e54
d e n t a l m a t e r i a l s 2 8 S ( 2 0 1 2 ) e1–e70
a Leica VMHT Mot (Germany) (50 gf, 30 s). The antimicrobial effect for different experimental Groups (Z, Z + 1% and Z + 2%) was tested regarding to the total number of Streptococcus mutans (CFU/mL) and direct contact inhibition was observed by scanning electron microscopy (SEM). Color parameters were analyzed in a spectrophotometer Color-guide 45/0, PCB 6807 (Byk Gardner GmbH, Gerestsried, Germany) to evaluate the color changes using CIE L*a*b* measuring system after 24 hs. E* values greater than or equal to 3.3 were considered as a clinically unacceptable color change and can be detected by the naked eye. Data for total number of Streptococcus mutans, VHN and color changes were submitted to one-way analysis of variance (ANOVA) and Tukey’s test at 0.05 significance level. Results: An 64% and 42.7% reduction in bacterial counts was observed with 1 and 2% (w/w) TiO2 containing composites compared with their control without nanoparticles, indicat-
Compound
Structural formula
ACP DCPA TCP
Ca2 P2 O7 ·H2 O CaHPO4 Ca3 (PO4 )2
Surface area (m2 /g)
Materials and methods: Commercial powders were used in the experiment (ACP and TCP from Sigma–Aldrich (St. Louis, MO, USA and DCPA from Synth, Diadema, Brazil). Particle structure (crystalline or amorphous) was characterized by Xray diffraction (XRD Rigaku MultiFlex, Tokyo, Japan). Surface area and particle size were determined using BET method (Quantacrome, 100E, München, Germany). Solutions of the different compounds were prepared with the same calcium concentration (in mols) and titration curves were obtained by adding 0. 01 mol L−1 of HCl (in 100 l increments) until a pH = 4 was reached. From the titration curves, the pH turning points (pH where the volume of added HCl was sufficient to neutralize the Ca2+ in the solution) and buffer bands (pH approximately constant even with addition of small amounts of acid) were obtained. Results: The diffractograms evidenced the ACP amorphous structure, while both DCPA and TCP showed crystalline structures. The other characteristics are shown in the table: Average particle size (nm)
30.9 2.95 3.14
ing a statistically significant suppression of biofilm growth. Microscopy demonstrated continuous biofilm formation for unmodified composite after seven day, but only sparsely distributed biofilms formed mainly on 1% TiO2 -containing composite. The VHN mean values were: ZT: 86.8 (±2.98), B: 83 (±2.01); Z1%T: 82.7 (±2.98), B: 78.3 (±2.55) and Z2%T: 89 (±2.08), B: 86.7 (±2.79). The TiO2 nanoparticles had a significant influence on the top and bottom surfaces, however top surface at 2% (w/w) showed no statistically significant difference. Regarding color changes (E*): Z: 0.625 (±0.41); Z1%: 0.586 (±0.36) and Z2%: 0.724 (±0.36) no statistical significantly differences were observed. Conclusions: The addition of 1 and 2% (w/w) nanoparticles affected VHN mean values, however did not provide significant color changes (E*). The results obtained indicate that 1% (w/w) TiO2 nanoparticles had a strong antibacterial activity. http://dx.doi.org/10.1016/j.dental.2012.07.125 119 Characterization of calcium phosphates used in bioactive composites M.C. Rodrigues 1,∗ , D.N. Souza 1 , T.L.R. Hewer 2 , G.E.S. Brito 3 , R.R. Braga 1 1
School of Dentistry, University of São Paulo, Brazil School of Engineering, University of São Paulo, Brazil 3 Institute of Physics, University of São Paulo, Brazil 2
Objectives: Characterize calcium phosphate compounds most commonly added to experimental dimethacrylate-based composites: amorphous calcium phosphate (ACP), dicalcium phosphate anhydrous (DCPA) and tricalcium phosphate (TCP).
65 371 314
pH turning point 5.52 5.48 5.24
Buffer band
7.1–6.4 and 4.4–4.0 4.5–4.0 6.6–6.0
Though pH turning points were similar, the amount of acid necessary to reach such pH was different (ACP: 3.6 mL, DCPA: 2.3 mL, TCP: 4.0 mL), indicating that TCP released the highest concentration of Ca2+ ions in solution, followed by ACP and DCPA. Conclusions: ACP, DCPA and TCP presented similar pH turning points. However, the amount of acid consumed in the titration suggests that TCP present a higher remineralizing potential. Also, TCP buffer band between 6.6 and 6.0 may offer some protection against severe pH drops (supported by CNPq). http://dx.doi.org/10.1016/j.dental.2012.07.126 120 Illuminant influences colorimetric parameters of resin matrix with varied camphorquinone J.P. Salomon 1,2,∗ , J.L. Ferracane 2 , J.J. Robin 3 , I. Krejci 4 , S. Ardu 4 1
Nancy, France Portland, OR, USA 3 Montpellier, France 4 Geneva, Switzerland 2
Objectives: The aim of the study was to assess the influence of the illuminants on the correlation between the percentage of camphorquinone (CQ) and the colorimetric parameters of a resin matrix for dental composites. Materials and methods: The experimental matrix contains CQ/EDMAB concentrations at 0.125, 0.25, 0.50, 0.75, 1.00, 1.50, 2% (mol.%) in a Bis-GMA/TEGDMA (80/20 wt.%). Ten 1.5 mm thick, disk-shaped samples were prepared for each experimental group by curing under a Mylar strip on both sides in a standard steel mold with a QTH light (Trilight Elipar –