- Email: [email protected]
Acoustic Emission Analysis of Tooth-Composite Interface Fracture
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cal region (−0.39 MPa for the model with cementum and −0.49 MPa for that without cementum). For the periodontal ligament (PDL) and cortical bone, both models presented the same values of highest minimum principal stress ( 3 ) (−0.20 MPa for the PDL and −0.22 for the cortical bone). The highest compressive stress presented for the PDL was obtained at the root apex. The equivalent stress showed similar stress distribution at root dentin, periodontal ligament (PDL), and cortical bone. Conclusions: The FEA analysis demonstrated that the cementum presence did not affect the stress distribution of PDL and cortical bone, while affected the distribution on root dentin. None of the models was able to explain the apical root resorption. New simulation conditions, mainly for the periodontal ligament, should be proposed in an attempt to obtain a precise stress distribution for orthodontic loading. http://dx.doi.org/10.1016/j.dental.2012.07.152
P11 Acoustic Emission Analysis of Tooth-Composite Interface Fracture H.J. Kweon ∗ , N.Y. Cho, I.B. Lee Seoul National University, Korea Objectives: To detect the interfacial debonding in the tooth-composite interface using the acoustic emission (AE) technique during composite curing, and to investigate the effect of composite properties, adhesive systems, and light curing methods on the AE characteristics and to relate them to the shrinkage kinetics of composites. Materials and methods: The polymerization shrinkage, peak shrinkage rate, flexural modulus and shrinkage stress of three composites (Z250, Z350 flowable, P90) were measured. Class I cavities were prepared on 49 extracted human premolars and divided into 7 groups (n = 7) and restored with one of the following protocols.
Group
Composite (Z250, Z350 flowable, P90)
Adhesive system (Scotchbond Multipurpose, Single Bond 2, Easy Bond, P90 Adhesive, 3M-ESPE, Clearfil SE Bond, Kuraray)
Light curing mode
Z250 Z250 Z250 Z250 P90 Z350 Z250
Z250 Z250 Z250 Z250 P90 (Silorane) Z350 flowable Z250
Scotchbond Multipurpose Single Bond 2 Clearfil SE Bond Easy Bond P90 System Adhesive Scotchbond Multipurpose Scotchbond Multipurpose
Conventional Conventional Conventional Conventional Conventional Conventional Exponential
SBMP SB CFSE EB SBMP Exp
AE signals were measured for 2000 s after the initiation of light curing. Results:
Z250 Z350 flowable P90
Polymerization shrinkage (%)
Peak shrinkage rate (%s−1 )
Peak time (s)
Flexural modulus (GPa)
Shrinkage stress (MPa)
2.15 3.95 1.65
0.24 0.45 0.12
2.84 3.37 6.01
9.20 4.74 7.60
9.09 11.25 8.12
Group
Mean AE events number
Total cumulative AE events number
Z250 Z250 Z250 Z250 P90 Z350 Z350
3.71 4.71 4.57 6.14 1.57 8.57 3.42
26 33 32 43 11 60 24
SBMP SB CFSE EB SBMP Exp
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Conclusions: The lower the shrinkage (rate) and slower polymerization reaction of composite results in the lower shrinkage stress and AE events number. The AE test is an effective technique to monitor the debonding kinetics at the tooth-composite interface during the composite restoration in real time.
Conclusions: In general, higher concentrations of camphorquinone promoted higher elastic modulus and yellowing values for the composites. The flexural strength was not affected by the initiator and co-initiator concentrations.
http://dx.doi.org/10.1016/j.dental.2012.07.153
P13 Photoinitiator and filler affect mechanical and optical properties of composites
P12 Physical–mechanical properties of composites formulated with different camphorquinone/amine concentrations L. Machado-Santos 1,∗ , C.V.S. Grohmann 2 , E.J. Souza-junior 2 , W.C. Brandt 3 , L. Correr-Sobrinho 2 , C.F. Carvalho 4 , E.A. Gazola 1 , M.A.C. Sinhoreti 2 1
UNITAU, Brazil UNICAMP, Brazil 3 UNISA, Brazil 4 UFF, Brazil 2
Objectives: The aim of this study was to evaluate the influence of camphorquinone and tertiary amine concentration on the flexural strength (FS), elastic modulus (EM) and yellowing (YL) of experimental composites. Materials and methods: BisGMA, UDMA, BisEMA and TEGDMA mixtures were prepared with different camphorquinone (CQ) and amine (EDMAB) concentrations (CQ/EDMAB): 0.4/0.4% (C1), 0.4/0.8% (C2), 0.6/0.6% (C3), 0.6/1.2 (C4), 0.8/0.8% (C5), 0.8/1.6% (C6), 1.0/1.0% (C7), 1.0/2.0% (C8), 1.5/1.5% (C9), 1.5/3.0% (C10). All specimens were photocured by LED, for 20s. For the FS and EM, rectangular specimens (7 mm × 2 mm × 1 mm, n = 10) were made and tested in a universal testing machine (Instron, 0.5 mm/min). For the YL, composite disks (6 mm diameter × 1 mm thickness, n = 10) were prepared and immediately evaluated in a spectrophotometer (Minolta), using the b aspect of the CIElab system. Data were submitted to one-way ANOVA and Tukey’s test at a pre-set alpha of 0.05. Results: Composites
Elastic modulus (GPa)
Flexural strength (MPa)
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
2.4 (0.5) CD 2.1 (0.4) D 2.6 (0.3) CD 2.8 (0.5) BC 2.7 (0.5) CD 2.6 (0.2) CD 2.6 (0.1) CD 2.7 (0.2) BC 3.3 (0.4) AB 3.9 (0.2) A
104.8 (27.5) A 107.0 (19.8) A 117.1 (23.1) A 110.2 (32.0) A 121.2 (22.1) A 127.4 (10.7) A 122.9 (13.6) A 122.1 (19.9) A 119.3 (19.3) A 125.5 (21.0) A
Yellowing
13.5 (1.1) EF 12.6 (2.8) F 16.3 (1.2) CDE 15.7 (1.6) ED 17.9 (0.8) BCD 16.2 (0.3) CDE 19.8 (0.6) B 19.0 (1.5) BC 24.4 (1.9) A 24.2 (0.7) A
Different letters in the column means statistical difference (5%).
http://dx.doi.org/10.1016/j.dental.2012.07.154
V.E. Salgado 1,∗ , P.P. Albuquerque 1 , L.M. Cavalcante 1 , L.F.J. Schneider 1,2 1 2
Federal Fluminense University, Brazil Veiga de Almeida University, Brazil
Objectives: The aim of this study was establish the relationship between photoinitiator system and the nanoparticle size on the optical properties and curing potential of experimental resin composites. Materials and methods: Experimental composites were formulated by a mixture of BisGMA:TEGDMA (60:40 mol%). This blend was then divided into six experimental groups that differed in the average particle size of inorganic content (R812 of 7 nm and R972 of 16 nm by Esstech Inc., USA), all at 40% by weight, and initiation system (CQ + EDMAB, TPO and BAPO), all at 1 mol.%: CQ + 7 nm, CQ + 16 nm, TPO + 7 nm, TPO + 16 nm, BAPO + 7 nm and BAPO + 16 nm. Specimens were manufactured by the photoactivation during 40 s with a large spectrum LED source (Bluephase G2, Ivoclar Vivadent, USA; irradiance = 1200 mW/cm2 ). Twenty-four hours after dry and dark storage, samples were submitted to optical properties analyses, and then stored in distilled water at 37 ◦ C. CIELAB, E* and translucency parameter (TP) were determined using a spectrophotometer (CM-2600d, Konica Minolta, Japan) by placing the samples over a white and a black background. Surface hardness (KHN) was determined at top and bottom surfaces with a Knoop indenter (Micromet 5104 - Buehler, Japan) under a load of 25 N for 15 s. Data were submitted to three-way (CIELab and TP) and one-way (KHN at top; bottom/top ratio and E) ANOVA and Tukey’s test at 95% of confidence.
d e n t a l m a t e r i a l s 2 8 S ( 2 0 1 2 ) e1–e70
cal region (−0.39 MPa for the model with cementum and −0.49 MPa for that without cementum). For the periodontal ligament (PDL) and cortical bone, both models presented the same values of highest minimum principal stress ( 3 ) (−0.20 MPa for the PDL and −0.22 for the cortical bone). The highest compressive stress presented for the PDL was obtained at the root apex. The equivalent stress showed similar stress distribution at root dentin, periodontal ligament (PDL), and cortical bone. Conclusions: The FEA analysis demonstrated that the cementum presence did not affect the stress distribution of PDL and cortical bone, while affected the distribution on root dentin. None of the models was able to explain the apical root resorption. New simulation conditions, mainly for the periodontal ligament, should be proposed in an attempt to obtain a precise stress distribution for orthodontic loading. http://dx.doi.org/10.1016/j.dental.2012.07.152
P11 Acoustic Emission Analysis of Tooth-Composite Interface Fracture H.J. Kweon ∗ , N.Y. Cho, I.B. Lee Seoul National University, Korea Objectives: To detect the interfacial debonding in the tooth-composite interface using the acoustic emission (AE) technique during composite curing, and to investigate the effect of composite properties, adhesive systems, and light curing methods on the AE characteristics and to relate them to the shrinkage kinetics of composites. Materials and methods: The polymerization shrinkage, peak shrinkage rate, flexural modulus and shrinkage stress of three composites (Z250, Z350 flowable, P90) were measured. Class I cavities were prepared on 49 extracted human premolars and divided into 7 groups (n = 7) and restored with one of the following protocols.
Group
Composite (Z250, Z350 flowable, P90)
Adhesive system (Scotchbond Multipurpose, Single Bond 2, Easy Bond, P90 Adhesive, 3M-ESPE, Clearfil SE Bond, Kuraray)
Light curing mode
Z250 Z250 Z250 Z250 P90 Z350 Z250
Z250 Z250 Z250 Z250 P90 (Silorane) Z350 flowable Z250
Scotchbond Multipurpose Single Bond 2 Clearfil SE Bond Easy Bond P90 System Adhesive Scotchbond Multipurpose Scotchbond Multipurpose
Conventional Conventional Conventional Conventional Conventional Conventional Exponential
SBMP SB CFSE EB SBMP Exp
AE signals were measured for 2000 s after the initiation of light curing. Results:
Z250 Z350 flowable P90
Polymerization shrinkage (%)
Peak shrinkage rate (%s−1 )
Peak time (s)
Flexural modulus (GPa)
Shrinkage stress (MPa)
2.15 3.95 1.65
0.24 0.45 0.12
2.84 3.37 6.01
9.20 4.74 7.60
9.09 11.25 8.12
Group
Mean AE events number
Total cumulative AE events number
Z250 Z250 Z250 Z250 P90 Z350 Z350
3.71 4.71 4.57 6.14 1.57 8.57 3.42
26 33 32 43 11 60 24
SBMP SB CFSE EB SBMP Exp
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Conclusions: The lower the shrinkage (rate) and slower polymerization reaction of composite results in the lower shrinkage stress and AE events number. The AE test is an effective technique to monitor the debonding kinetics at the tooth-composite interface during the composite restoration in real time.
Conclusions: In general, higher concentrations of camphorquinone promoted higher elastic modulus and yellowing values for the composites. The flexural strength was not affected by the initiator and co-initiator concentrations.
http://dx.doi.org/10.1016/j.dental.2012.07.153
P13 Photoinitiator and filler affect mechanical and optical properties of composites
P12 Physical–mechanical properties of composites formulated with different camphorquinone/amine concentrations L. Machado-Santos 1,∗ , C.V.S. Grohmann 2 , E.J. Souza-junior 2 , W.C. Brandt 3 , L. Correr-Sobrinho 2 , C.F. Carvalho 4 , E.A. Gazola 1 , M.A.C. Sinhoreti 2 1
UNITAU, Brazil UNICAMP, Brazil 3 UNISA, Brazil 4 UFF, Brazil 2
Objectives: The aim of this study was to evaluate the influence of camphorquinone and tertiary amine concentration on the flexural strength (FS), elastic modulus (EM) and yellowing (YL) of experimental composites. Materials and methods: BisGMA, UDMA, BisEMA and TEGDMA mixtures were prepared with different camphorquinone (CQ) and amine (EDMAB) concentrations (CQ/EDMAB): 0.4/0.4% (C1), 0.4/0.8% (C2), 0.6/0.6% (C3), 0.6/1.2 (C4), 0.8/0.8% (C5), 0.8/1.6% (C6), 1.0/1.0% (C7), 1.0/2.0% (C8), 1.5/1.5% (C9), 1.5/3.0% (C10). All specimens were photocured by LED, for 20s. For the FS and EM, rectangular specimens (7 mm × 2 mm × 1 mm, n = 10) were made and tested in a universal testing machine (Instron, 0.5 mm/min). For the YL, composite disks (6 mm diameter × 1 mm thickness, n = 10) were prepared and immediately evaluated in a spectrophotometer (Minolta), using the b aspect of the CIElab system. Data were submitted to one-way ANOVA and Tukey’s test at a pre-set alpha of 0.05. Results: Composites
Elastic modulus (GPa)
Flexural strength (MPa)
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
2.4 (0.5) CD 2.1 (0.4) D 2.6 (0.3) CD 2.8 (0.5) BC 2.7 (0.5) CD 2.6 (0.2) CD 2.6 (0.1) CD 2.7 (0.2) BC 3.3 (0.4) AB 3.9 (0.2) A
104.8 (27.5) A 107.0 (19.8) A 117.1 (23.1) A 110.2 (32.0) A 121.2 (22.1) A 127.4 (10.7) A 122.9 (13.6) A 122.1 (19.9) A 119.3 (19.3) A 125.5 (21.0) A
Yellowing
13.5 (1.1) EF 12.6 (2.8) F 16.3 (1.2) CDE 15.7 (1.6) ED 17.9 (0.8) BCD 16.2 (0.3) CDE 19.8 (0.6) B 19.0 (1.5) BC 24.4 (1.9) A 24.2 (0.7) A
Different letters in the column means statistical difference (5%).
http://dx.doi.org/10.1016/j.dental.2012.07.154
V.E. Salgado 1,∗ , P.P. Albuquerque 1 , L.M. Cavalcante 1 , L.F.J. Schneider 1,2 1 2
Federal Fluminense University, Brazil Veiga de Almeida University, Brazil
Objectives: The aim of this study was establish the relationship between photoinitiator system and the nanoparticle size on the optical properties and curing potential of experimental resin composites. Materials and methods: Experimental composites were formulated by a mixture of BisGMA:TEGDMA (60:40 mol%). This blend was then divided into six experimental groups that differed in the average particle size of inorganic content (R812 of 7 nm and R972 of 16 nm by Esstech Inc., USA), all at 40% by weight, and initiation system (CQ + EDMAB, TPO and BAPO), all at 1 mol.%: CQ + 7 nm, CQ + 16 nm, TPO + 7 nm, TPO + 16 nm, BAPO + 7 nm and BAPO + 16 nm. Specimens were manufactured by the photoactivation during 40 s with a large spectrum LED source (Bluephase G2, Ivoclar Vivadent, USA; irradiance = 1200 mW/cm2 ). Twenty-four hours after dry and dark storage, samples were submitted to optical properties analyses, and then stored in distilled water at 37 ◦ C. CIELAB, E* and translucency parameter (TP) were determined using a spectrophotometer (CM-2600d, Konica Minolta, Japan) by placing the samples over a white and a black background. Surface hardness (KHN) was determined at top and bottom surfaces with a Knoop indenter (Micromet 5104 - Buehler, Japan) under a load of 25 N for 15 s. Data were submitted to three-way (CIELab and TP) and one-way (KHN at top; bottom/top ratio and E) ANOVA and Tukey’s test at 95% of confidence.