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Preparation of nanocomposite resin block using the FPMI method
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d e n t a l m a t e r i a l s 3 3 S ( 2 0 1 7 ) e1–e92
117 Effect of prolonged-storage on tensile bond strength of adhesive systems M. Noda ∗ , N. Okada, M. Ito, R. Yagi, H. Sakurai, H. Shiga, A. Asano Department of Conservative Dentistry, School of Dentistry, Iwate Medical University, Morioka, Japan Purpose/aim: The purpose of this study was to evaluate the tensile bond strength of the universal adhesive systems to repair ceramic restorations before and after their expiry dates. Materials and methods: Three types of the universal adhesive systems (SU, Scotchbond Universal Adhesive, 3M; CP, G-Premio bond/Ceramic Primer, GC; UP, Bond Force II/Universal Primer, Tokuyama Dental) were tested in this study. All bonding systems were tested before or after 2 months of each expiry date. Surfaces of the ceramic blocks (Ceram Block, GC) were grinded with #600 SiC paper and ultrasonicated for 10 min. Each adhesive system was applied on the surface according to the manufacturer’s instructions. Then a cylindrical stainless mold (3.0 mm height, 4.0 mm diameter) was put on the surface and resin composite was filled (MI LOW FLOW, GC). Tensile bond strength, TBS, was measured by universal testing machine, cross head speed at 0.5 mm/min, after the specimens were stored in distilled water at 37 ◦ C for 24 h. The data were statistically analyzed by two-way ANOVA and Tukey-HSD (p < 0.05, n = 12). The components of adhesive systems tested in this study were analyzed to compare between before and after their expiry dates by HPLC. Results: Whereas TBS before the expiry dates showed 13.2 ± 6.2 MPa for SU, 15.4 ± 3.2 MPa for CP, and 17.5 ± 5.9 MPa for UP, TBS after expired were significantly decreased in all products, 8.1 ± 2.4 MPa for SU, 10.3 ± 3.0 MPa for CP, and 13.1 ± 3.0 MPa for UP. There was no intersection between expiry date and products. For HPLC analysis, some shifted peaks which seemed to be hydrolyzates of ␥-MPTS appeared in the expired bonding systems tested. Conclusions: The results in this study suggested that the component for Si-coupling, ␥-MPTS, of adhesive systems might be hydrolyzed during storage and the tensile bond strength would be affected. http://dx.doi.org/10.1016/j.dental.2017.08.118 118 Fractographic analyses of dentin M. Øilo 1,2,∗ , W. Yan 2 , D. Arola 2 1 2
University of Bergen, Norway University of Washington, Seattle, USA
Purpose/aim: Cracked teeth often cause pain and discomfort. Although a common clinical problem, there are no rules for prevention or intervention. It is of tremendous importance to understand the principal causes of fractures in teeth, which can help in developing guidelines for prevention and treatment. The aim of this study was to characterize
the fractographic features of dentin resulting from static and cyclic loading to failure. Materials and methods: Twenty rectangular beam specimens of radicular dentin were obtained from young and old donors and subjected to static (n = 14) or cyclic (n = 6) four-point flexure to failure. Each was inspected by SEM and analyzed using standard fractographic methods. Results: The fracture origin and direction of crack propagation was identified in all specimens. The fractographic features included initial crack, compression curls and arrest lines. There were differences between specimens that failed by static or cyclic loading, although not very distinct. Multiple arrest lines were present in specimens that failed by fatigue, whereas most specimens fractured during static loading did not exhibit distinct arrest lines beyond the initial crack. The tortuosity of the surface created by the dentin tubules complicated interpretation since the features were often partial or non-continuous. Conclusions: The findings show that fractography can be used for identifying fracture origins and direction of crack propagation in dentin. Furthermore, it can be used to understand the conditions of loading that facilitated the fracture of teeth in vivo. http://dx.doi.org/10.1016/j.dental.2017.08.119 119 Preparation of nanocomposite resin block using the FPMI method K. Okada 1,2,∗ , T. Kameya 2 , H. Ishino 2 , T. Hayakawa 1 1
Department of Dental Engineering, Tsurumi University School of Dental Medicine, Yokohama, Japan 2 Kuraray Noritake Dental Inc., Tokyo, Japan Purpose/aim: We have developed a new technique of preparing dental CAD/CAM composite resin blocks (CRBs): the filler press and monomer infiltration (FPMI) method. The purpose of this study was to prepare the nanocomposite resin block in which the nanofiller is uniformly dispersed and extrahigh densely packed using the FPMI method. Materials and methods: A fine silica powder (Aerosil OX50, average particle size: 40 nm) was surface-treated using 3-methacryloxypropyltrimethoxysilane and used as the inorganic filler. The monomer mixture was comprised of 49.48 wt% UDMA, 49.48 wt% TEGDEMA, 0.99 wt% benzoyl peroxide and 0.05 wt% acylphosphine oxide (Lucirin TPO). A stainless die with an internal capacity of 33 mm × 24 mm and two punches were used for uni-axial press. 5.5 g of inorganic filler was placed in the die, which is compressed from both the top and bottom using two punches at 60 kN (76 MPa) for 60 s. After pressing, the block-shaped green body of nanosilica filler was taken out of the die. The blocks pressed were sealed in a vinyl bag and subjected to cold isostatic pressing (CIP) at 170 MPa and 950 MPa for 60 s respectively. The resulted nanosilica green bodies were immersed in the monomer mixture for 5 days. The translucent monomer-infiltrated green bodies were obtained, followed by the polymerization with the
d e n t a l m a t e r i a l s 3 3 S ( 2 0 1 7 ) e1–e92
Fig. 1
light-curing for 3 min and then heated at 120 ◦ C for 2 h, resulting in the hard nanocomposite resin blocks, CRB1 (170 MPa) and CRB2 (950 MPa). The inorganic filler content was measured by ignition residue at 600 ◦ C and the volume content was calculated by the gravity of nanosilica and matrix polymer. TEM observations were carried with the 50 nm thickness sectioned specimen. The flexural strengths were measured according to ISO4049, the specimens, 2 mm × 2 mm × 25 mm, were cut from the CRB using a diamond saw. Results: The inorganic filler contents were 70.1 wt% (56 vol%) for CRB1 and 76.0 wt% (64 vol%) for CRB2. The TEM images of the CRB (Fig. 1) reveal that the nanofiller are uniformly and densely distributed. The flexural strengths were 201 MPa for CRB1 and 208 MPa for CRB2, the flexural modulus were 10.1 GPa for CRB1 and 15.2 GPa for CRB2. Conclusions: The greater the pressure of the nanofiller molding in the FPMI method, the more nanofiller in the CRB resulting in a high elastic modulus CRB. The nanocomposite material in this study will be useful for the fabrication of permanent resin crown. http://dx.doi.org/10.1016/j.dental.2017.08.120 120 Can glass ionomer cements inhibit cariogenic species? In vitro study N.A. Oliveira ∗ , F.B. Andrade, I.F. Leão, S.K. Ishikiriama, J.F.S. Bombonatti Department of Operative Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil Purpose/aim: The objective of this in vitro study was to determine whether glass ionomer cements (GICs) can inhibit bacteria involved in caries lesion process. For this, three strains were selected: Streptococcus mutans (ATCC 25175), Lactobacillus casei (ATCC 334) and Bifidobacterium dentium (ATCC 27534). Materials and methods: Three GICs were tested, two conventional GICs (Fuji IX Extra and IonZ – a new GIC available in Brazil, that present in its composition zinc oxide particles) and one resin modified GIC (Fuji II LC) using two methodology: agar diffusion test and direct contact test. The GICs were tested immediately after manipulation (I) and after 10 min (M). For the agar diffusion test the mean inhibition zones in millime-
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ters were measured and for direct contact test the number of colony forming units was evaluated by scores. The tests were done in triplicate. Results: For S. mutans, just Fuji IX Extra (I) and Ion-Z (I) presented inhibition zones of 3.00 (±5.19) and 10.66 (±4.61) mm respectively in agar diffusion test, and, a score of 3 (dense bacterial growth) for direct contact test. L. casei was inhibited in agar diffusion test by Fuji IX Extra (I) and (M), Ion-Z (I) and (M), and the major inhibition zone was for Fuji IX Extra (M) with 14.00 (±1.73) mm. In direct contact test, L. casei presented a score 2, a moderate bacterial growth against the cements. In agar diffusion test, B. dentium was inhibited by Fuji IX Extra (M) with 9.33 (±8.14) mm, Ion-Z (M) 7.33 (±1.52) mm and Ion-Z (I) 6.33 (±5.68) mm of inhibition zones. In direct contact test, Fuji II LC (I) allowed a higher B. dentium growth (score 3), and the others GICs I or M presented a slight bacterial growth (score between 1.66 and 2.22). Conclusions: The conventional GICs (Fuji IX Extra and Ion-Z) could inhibit the growth of cariogenic species, varying among bacteria. B. dentium demonstrated lower resistance against the conventional GICs tested. The resin modified GIC (Fuji II LC) could not present inhibition zones for the bacteria tested in this in vitro study. http://dx.doi.org/10.1016/j.dental.2017.08.121 121 Adhesion of resin–resin and resin–lithium-disilicate ceramic: A methodological assessment N. Al-Haj Husain, A. Alshihri, M. Özcan ∗ Division of Dental Materials, University of Zurich, Zurich, Switzerland Purpose/aim: Dental literature contains overwhelming amount of work on adhesion to dental ceramics but several test methods have not been studied in one investigation. This study compared the adhesion of resin composite to resin and lithium-disilicate ceramic using four common adhesion test methods. Materials and methods: Resin composite specimens (N = 180, Quadrant Universal LC) were obtained and randomly assigned to test the adhesion to resin composite (Quadrant Universal LC) and lithium disilicate ceramic (IPS e.max CAD) using one of the following test methods: (a) macroshear test (SBT) (n = 30), (b) macrotensile test (TBT) (n = 30), (c) microshear test (SBT) (n = 30) and (d) microtensile test (TBT) (n = 6, ncomposite : 216, nceramic : 216). Bonded specimens were stored for 24 h at 23 ◦ C. Adhesion tests were performed in a Universal Testing Machine (1 mm/min) and failure types were analyzed after debonding. Data were analyzed using Univariate and Tukey’s, Bonneferroni post-hoc test (alpha = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Results: Both the test method (p < 0.05) and adherendsubstrate type (p < 0.05) significantly affected the adhesion results. Interaction terms were also significant (p < 0.05). When testing adhesion of resin to resin, SBT (24.4 ± 5)a, TBT (16.1 ± 4.4)b and SBT (20.6 ± 7.4)a,b test methods showed
d e n t a l m a t e r i a l s 3 3 S ( 2 0 1 7 ) e1–e92
117 Effect of prolonged-storage on tensile bond strength of adhesive systems M. Noda ∗ , N. Okada, M. Ito, R. Yagi, H. Sakurai, H. Shiga, A. Asano Department of Conservative Dentistry, School of Dentistry, Iwate Medical University, Morioka, Japan Purpose/aim: The purpose of this study was to evaluate the tensile bond strength of the universal adhesive systems to repair ceramic restorations before and after their expiry dates. Materials and methods: Three types of the universal adhesive systems (SU, Scotchbond Universal Adhesive, 3M; CP, G-Premio bond/Ceramic Primer, GC; UP, Bond Force II/Universal Primer, Tokuyama Dental) were tested in this study. All bonding systems were tested before or after 2 months of each expiry date. Surfaces of the ceramic blocks (Ceram Block, GC) were grinded with #600 SiC paper and ultrasonicated for 10 min. Each adhesive system was applied on the surface according to the manufacturer’s instructions. Then a cylindrical stainless mold (3.0 mm height, 4.0 mm diameter) was put on the surface and resin composite was filled (MI LOW FLOW, GC). Tensile bond strength, TBS, was measured by universal testing machine, cross head speed at 0.5 mm/min, after the specimens were stored in distilled water at 37 ◦ C for 24 h. The data were statistically analyzed by two-way ANOVA and Tukey-HSD (p < 0.05, n = 12). The components of adhesive systems tested in this study were analyzed to compare between before and after their expiry dates by HPLC. Results: Whereas TBS before the expiry dates showed 13.2 ± 6.2 MPa for SU, 15.4 ± 3.2 MPa for CP, and 17.5 ± 5.9 MPa for UP, TBS after expired were significantly decreased in all products, 8.1 ± 2.4 MPa for SU, 10.3 ± 3.0 MPa for CP, and 13.1 ± 3.0 MPa for UP. There was no intersection between expiry date and products. For HPLC analysis, some shifted peaks which seemed to be hydrolyzates of ␥-MPTS appeared in the expired bonding systems tested. Conclusions: The results in this study suggested that the component for Si-coupling, ␥-MPTS, of adhesive systems might be hydrolyzed during storage and the tensile bond strength would be affected. http://dx.doi.org/10.1016/j.dental.2017.08.118 118 Fractographic analyses of dentin M. Øilo 1,2,∗ , W. Yan 2 , D. Arola 2 1 2
University of Bergen, Norway University of Washington, Seattle, USA
Purpose/aim: Cracked teeth often cause pain and discomfort. Although a common clinical problem, there are no rules for prevention or intervention. It is of tremendous importance to understand the principal causes of fractures in teeth, which can help in developing guidelines for prevention and treatment. The aim of this study was to characterize
the fractographic features of dentin resulting from static and cyclic loading to failure. Materials and methods: Twenty rectangular beam specimens of radicular dentin were obtained from young and old donors and subjected to static (n = 14) or cyclic (n = 6) four-point flexure to failure. Each was inspected by SEM and analyzed using standard fractographic methods. Results: The fracture origin and direction of crack propagation was identified in all specimens. The fractographic features included initial crack, compression curls and arrest lines. There were differences between specimens that failed by static or cyclic loading, although not very distinct. Multiple arrest lines were present in specimens that failed by fatigue, whereas most specimens fractured during static loading did not exhibit distinct arrest lines beyond the initial crack. The tortuosity of the surface created by the dentin tubules complicated interpretation since the features were often partial or non-continuous. Conclusions: The findings show that fractography can be used for identifying fracture origins and direction of crack propagation in dentin. Furthermore, it can be used to understand the conditions of loading that facilitated the fracture of teeth in vivo. http://dx.doi.org/10.1016/j.dental.2017.08.119 119 Preparation of nanocomposite resin block using the FPMI method K. Okada 1,2,∗ , T. Kameya 2 , H. Ishino 2 , T. Hayakawa 1 1
Department of Dental Engineering, Tsurumi University School of Dental Medicine, Yokohama, Japan 2 Kuraray Noritake Dental Inc., Tokyo, Japan Purpose/aim: We have developed a new technique of preparing dental CAD/CAM composite resin blocks (CRBs): the filler press and monomer infiltration (FPMI) method. The purpose of this study was to prepare the nanocomposite resin block in which the nanofiller is uniformly dispersed and extrahigh densely packed using the FPMI method. Materials and methods: A fine silica powder (Aerosil OX50, average particle size: 40 nm) was surface-treated using 3-methacryloxypropyltrimethoxysilane and used as the inorganic filler. The monomer mixture was comprised of 49.48 wt% UDMA, 49.48 wt% TEGDEMA, 0.99 wt% benzoyl peroxide and 0.05 wt% acylphosphine oxide (Lucirin TPO). A stainless die with an internal capacity of 33 mm × 24 mm and two punches were used for uni-axial press. 5.5 g of inorganic filler was placed in the die, which is compressed from both the top and bottom using two punches at 60 kN (76 MPa) for 60 s. After pressing, the block-shaped green body of nanosilica filler was taken out of the die. The blocks pressed were sealed in a vinyl bag and subjected to cold isostatic pressing (CIP) at 170 MPa and 950 MPa for 60 s respectively. The resulted nanosilica green bodies were immersed in the monomer mixture for 5 days. The translucent monomer-infiltrated green bodies were obtained, followed by the polymerization with the
d e n t a l m a t e r i a l s 3 3 S ( 2 0 1 7 ) e1–e92
Fig. 1
light-curing for 3 min and then heated at 120 ◦ C for 2 h, resulting in the hard nanocomposite resin blocks, CRB1 (170 MPa) and CRB2 (950 MPa). The inorganic filler content was measured by ignition residue at 600 ◦ C and the volume content was calculated by the gravity of nanosilica and matrix polymer. TEM observations were carried with the 50 nm thickness sectioned specimen. The flexural strengths were measured according to ISO4049, the specimens, 2 mm × 2 mm × 25 mm, were cut from the CRB using a diamond saw. Results: The inorganic filler contents were 70.1 wt% (56 vol%) for CRB1 and 76.0 wt% (64 vol%) for CRB2. The TEM images of the CRB (Fig. 1) reveal that the nanofiller are uniformly and densely distributed. The flexural strengths were 201 MPa for CRB1 and 208 MPa for CRB2, the flexural modulus were 10.1 GPa for CRB1 and 15.2 GPa for CRB2. Conclusions: The greater the pressure of the nanofiller molding in the FPMI method, the more nanofiller in the CRB resulting in a high elastic modulus CRB. The nanocomposite material in this study will be useful for the fabrication of permanent resin crown. http://dx.doi.org/10.1016/j.dental.2017.08.120 120 Can glass ionomer cements inhibit cariogenic species? In vitro study N.A. Oliveira ∗ , F.B. Andrade, I.F. Leão, S.K. Ishikiriama, J.F.S. Bombonatti Department of Operative Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil Purpose/aim: The objective of this in vitro study was to determine whether glass ionomer cements (GICs) can inhibit bacteria involved in caries lesion process. For this, three strains were selected: Streptococcus mutans (ATCC 25175), Lactobacillus casei (ATCC 334) and Bifidobacterium dentium (ATCC 27534). Materials and methods: Three GICs were tested, two conventional GICs (Fuji IX Extra and IonZ – a new GIC available in Brazil, that present in its composition zinc oxide particles) and one resin modified GIC (Fuji II LC) using two methodology: agar diffusion test and direct contact test. The GICs were tested immediately after manipulation (I) and after 10 min (M). For the agar diffusion test the mean inhibition zones in millime-
e61
ters were measured and for direct contact test the number of colony forming units was evaluated by scores. The tests were done in triplicate. Results: For S. mutans, just Fuji IX Extra (I) and Ion-Z (I) presented inhibition zones of 3.00 (±5.19) and 10.66 (±4.61) mm respectively in agar diffusion test, and, a score of 3 (dense bacterial growth) for direct contact test. L. casei was inhibited in agar diffusion test by Fuji IX Extra (I) and (M), Ion-Z (I) and (M), and the major inhibition zone was for Fuji IX Extra (M) with 14.00 (±1.73) mm. In direct contact test, L. casei presented a score 2, a moderate bacterial growth against the cements. In agar diffusion test, B. dentium was inhibited by Fuji IX Extra (M) with 9.33 (±8.14) mm, Ion-Z (M) 7.33 (±1.52) mm and Ion-Z (I) 6.33 (±5.68) mm of inhibition zones. In direct contact test, Fuji II LC (I) allowed a higher B. dentium growth (score 3), and the others GICs I or M presented a slight bacterial growth (score between 1.66 and 2.22). Conclusions: The conventional GICs (Fuji IX Extra and Ion-Z) could inhibit the growth of cariogenic species, varying among bacteria. B. dentium demonstrated lower resistance against the conventional GICs tested. The resin modified GIC (Fuji II LC) could not present inhibition zones for the bacteria tested in this in vitro study. http://dx.doi.org/10.1016/j.dental.2017.08.121 121 Adhesion of resin–resin and resin–lithium-disilicate ceramic: A methodological assessment N. Al-Haj Husain, A. Alshihri, M. Özcan ∗ Division of Dental Materials, University of Zurich, Zurich, Switzerland Purpose/aim: Dental literature contains overwhelming amount of work on adhesion to dental ceramics but several test methods have not been studied in one investigation. This study compared the adhesion of resin composite to resin and lithium-disilicate ceramic using four common adhesion test methods. Materials and methods: Resin composite specimens (N = 180, Quadrant Universal LC) were obtained and randomly assigned to test the adhesion to resin composite (Quadrant Universal LC) and lithium disilicate ceramic (IPS e.max CAD) using one of the following test methods: (a) macroshear test (SBT) (n = 30), (b) macrotensile test (TBT) (n = 30), (c) microshear test (SBT) (n = 30) and (d) microtensile test (TBT) (n = 6, ncomposite : 216, nceramic : 216). Bonded specimens were stored for 24 h at 23 ◦ C. Adhesion tests were performed in a Universal Testing Machine (1 mm/min) and failure types were analyzed after debonding. Data were analyzed using Univariate and Tukey’s, Bonneferroni post-hoc test (alpha = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Results: Both the test method (p < 0.05) and adherendsubstrate type (p < 0.05) significantly affected the adhesion results. Interaction terms were also significant (p < 0.05). When testing adhesion of resin to resin, SBT (24.4 ± 5)a, TBT (16.1 ± 4.4)b and SBT (20.6 ± 7.4)a,b test methods showed