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Alternative acid-functional monomer and its pH influence on the enamel
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d e n t a l m a t e r i a l s 3 0 S ( 2 0 1 4 ) e1–e180
similar efficacy of polymerization, however CQ shows higher SS. Composites containing BAPO show superior quality of polymerization and lower SS when compared to CQ and PPD. The co-initiator is necessary for composites containing CQ or PPD, but not for composites containing BAPO. BAPO is a suitable substitute for CQ, as a photoinitiator in resin composites.
169
Keywords: Camphorquinone; Photoinitiator; Composite
1
http://dx.doi.org/10.1016/j.dental.2014.08.168 168 Alternative acid-functional monomer and its pH influence on the enamel A.F. Da Silva ∗ , E.A. Münchow, M. Barbosa, G.S. Lima, F.A. Ogliari, E. Piv Federal University of Pelotas, Brazil Purpose: The aim of this study was to synthesize an alternative acidic monomer (polypropylene glycol phosphate methacrylate – Poly-P) to constitute experimental two-step self-etch adhesive systems and to evaluate its influence on the pH and microshear bond strength (SBS) to enamel. Methods and materials: Four primers containing Poly-P (10, 15, 30 or 50 wt%), 2-hydroxyethyl methacrylate (HEMA), ethanol, and water were prepared, which were allocated in two subgroups according to an adjusted (buffered) or non-adjusted (non-buffered) pH. One experimental control and one commercial (ClearfillTM SE Bond) references were used. SBS protocol was performed at human enamel, followed by mechanical testing (EMIC). Scanning Electron Microscopy (SEM) was performed after each primer application. Data was analyzed by One-Way Kruskall–Wallis and Student-Newman–Keuls tests (p < 0.05) and by linear regression predictive models. Results: As greater the Poly-P content, the lower the primer’s pH. Buffered groups showed lower SBS values than non-buffered groups. Groups with Poly-P content equal or higher than 30 wt% showed similar SBS results when compared to the controls. SEM images demonstrated that only primers with high Poly-P content (30 and 50 wt%) etched enamel in a more evidenced Type 1 (prisms exposure) etching pattern. Conclusion: The pH of the primer was directly influenced by the concentration of acidic monomer, which directly affected the enamel bond strength results. Poly-P is a potential monomer to be used in the formulation of self-etch dental adhesive systems. Keywords: Dental adhesive; Micro-shear bond strength; Selfetching
Polymerization of self-etching resin-cements: Effect of storage time and light-curing-technique B. Dimarco 1 , C. Solomon 2 , R. Franc¸a 1,∗ Dental Biomaterials Research Laboratory, Department of Restorative Dentistry, Faculty of Dentistry, University of Manitoba – Winnipeg, Canada 2 Prosthodontics Division, Department of Restorative Dentistry, Faculty of Dentistry, University of Manitoba – Winnipeg, Canada
Purpose: The aim of this study was to analyze the degree of conversion of four self-etching resin cements according to two light curing sources and during three different periods of time. Methods and materials: Four different commercial brands of self-etching resin cements were used (n = 6): RelyX Unicem 2 (3M Inc.), Bifix SE (Voco GmbH), BisCem (Bisco, Inc.) and Embrace WetBond (Pulpdent Inc). For these Resin Cements, two different polymerization techniques were used: quartztungsten-halogen (QTH) light curing (Max Caulk, Dentsply) versus light-emitting diode (LED) curing (Valo Cordless, Ultradent Products Inc). All cements were manipulated and applied according to the manufacturers’ instructions. The QTH light had an intensity of 450 mW/cm2 , and the LED light had an intensity of 750 mW/cm2 . After polymerization, samples were stored at 37 ◦ C. Degree of conversion (DC) data was recorded in three different time increments: 10 min, 24 h and 15 days. The DC was performed using a Fourier Transformation Infrared (FTIR; Nicoler-6700). DC was calculated utilizing C C (1640 cm−1 ) and C C (1608 cm−1 ) ratio between polymerized and unpolymerized resin cements. Data were analyzed by a two-way ANOVA and Bonferroni post hoc test (p < 0.05). Results: Table below reports the average percent (DC) and the standard deviation. Curing
Time
RelyX 2
Bifix SE
BisCEm
Embrace
LED
10 min 31.0 (±6.4) 24 h 34.0 (±5.2) 15 days 37.4 (±1.7)
29.5 (±2.0) 21.6 (±3.0) 27.5 (±5.2)
29.5 (±2.0) 38.4 (±3.0) 32.2 (±5.2)
13.1 (±1.9) 17.8 (±3.0) 22.6 (±6.7)
QTH
10 min 31.5 (±3.4) 24 h 36.9 (±4.2) 15 days 35.7 (±3.0)
23.5 (±3.1) 30.3 (±1.9) 28.2 (±5.5)
23.5 (±5.2) 30.3 (±1.9) 28.1 (±5.4)
29.7 (±3.9) 30.4 (±3.1) 28.1 (±5.6)
Conclusion: Factors: Light curing technique, storage time and resin cements and the interaction between them are significantly different (p < 0.05). Depending on the brand, the choice of the light curing technique should be used to improve the degree of conversion. Keywords: Self-etching resin cements; Degree of conversion
http://dx.doi.org/10.1016/j.dental.2014.08.169 http://dx.doi.org/10.1016/j.dental.2014.08.170
d e n t a l m a t e r i a l s 3 0 S ( 2 0 1 4 ) e1–e180
similar efficacy of polymerization, however CQ shows higher SS. Composites containing BAPO show superior quality of polymerization and lower SS when compared to CQ and PPD. The co-initiator is necessary for composites containing CQ or PPD, but not for composites containing BAPO. BAPO is a suitable substitute for CQ, as a photoinitiator in resin composites.
169
Keywords: Camphorquinone; Photoinitiator; Composite
1
http://dx.doi.org/10.1016/j.dental.2014.08.168 168 Alternative acid-functional monomer and its pH influence on the enamel A.F. Da Silva ∗ , E.A. Münchow, M. Barbosa, G.S. Lima, F.A. Ogliari, E. Piv Federal University of Pelotas, Brazil Purpose: The aim of this study was to synthesize an alternative acidic monomer (polypropylene glycol phosphate methacrylate – Poly-P) to constitute experimental two-step self-etch adhesive systems and to evaluate its influence on the pH and microshear bond strength (SBS) to enamel. Methods and materials: Four primers containing Poly-P (10, 15, 30 or 50 wt%), 2-hydroxyethyl methacrylate (HEMA), ethanol, and water were prepared, which were allocated in two subgroups according to an adjusted (buffered) or non-adjusted (non-buffered) pH. One experimental control and one commercial (ClearfillTM SE Bond) references were used. SBS protocol was performed at human enamel, followed by mechanical testing (EMIC). Scanning Electron Microscopy (SEM) was performed after each primer application. Data was analyzed by One-Way Kruskall–Wallis and Student-Newman–Keuls tests (p < 0.05) and by linear regression predictive models. Results: As greater the Poly-P content, the lower the primer’s pH. Buffered groups showed lower SBS values than non-buffered groups. Groups with Poly-P content equal or higher than 30 wt% showed similar SBS results when compared to the controls. SEM images demonstrated that only primers with high Poly-P content (30 and 50 wt%) etched enamel in a more evidenced Type 1 (prisms exposure) etching pattern. Conclusion: The pH of the primer was directly influenced by the concentration of acidic monomer, which directly affected the enamel bond strength results. Poly-P is a potential monomer to be used in the formulation of self-etch dental adhesive systems. Keywords: Dental adhesive; Micro-shear bond strength; Selfetching
Polymerization of self-etching resin-cements: Effect of storage time and light-curing-technique B. Dimarco 1 , C. Solomon 2 , R. Franc¸a 1,∗ Dental Biomaterials Research Laboratory, Department of Restorative Dentistry, Faculty of Dentistry, University of Manitoba – Winnipeg, Canada 2 Prosthodontics Division, Department of Restorative Dentistry, Faculty of Dentistry, University of Manitoba – Winnipeg, Canada
Purpose: The aim of this study was to analyze the degree of conversion of four self-etching resin cements according to two light curing sources and during three different periods of time. Methods and materials: Four different commercial brands of self-etching resin cements were used (n = 6): RelyX Unicem 2 (3M Inc.), Bifix SE (Voco GmbH), BisCem (Bisco, Inc.) and Embrace WetBond (Pulpdent Inc). For these Resin Cements, two different polymerization techniques were used: quartztungsten-halogen (QTH) light curing (Max Caulk, Dentsply) versus light-emitting diode (LED) curing (Valo Cordless, Ultradent Products Inc). All cements were manipulated and applied according to the manufacturers’ instructions. The QTH light had an intensity of 450 mW/cm2 , and the LED light had an intensity of 750 mW/cm2 . After polymerization, samples were stored at 37 ◦ C. Degree of conversion (DC) data was recorded in three different time increments: 10 min, 24 h and 15 days. The DC was performed using a Fourier Transformation Infrared (FTIR; Nicoler-6700). DC was calculated utilizing C C (1640 cm−1 ) and C C (1608 cm−1 ) ratio between polymerized and unpolymerized resin cements. Data were analyzed by a two-way ANOVA and Bonferroni post hoc test (p < 0.05). Results: Table below reports the average percent (DC) and the standard deviation. Curing
Time
RelyX 2
Bifix SE
BisCEm
Embrace
LED
10 min 31.0 (±6.4) 24 h 34.0 (±5.2) 15 days 37.4 (±1.7)
29.5 (±2.0) 21.6 (±3.0) 27.5 (±5.2)
29.5 (±2.0) 38.4 (±3.0) 32.2 (±5.2)
13.1 (±1.9) 17.8 (±3.0) 22.6 (±6.7)
QTH
10 min 31.5 (±3.4) 24 h 36.9 (±4.2) 15 days 35.7 (±3.0)
23.5 (±3.1) 30.3 (±1.9) 28.2 (±5.5)
23.5 (±5.2) 30.3 (±1.9) 28.1 (±5.4)
29.7 (±3.9) 30.4 (±3.1) 28.1 (±5.6)
Conclusion: Factors: Light curing technique, storage time and resin cements and the interaction between them are significantly different (p < 0.05). Depending on the brand, the choice of the light curing technique should be used to improve the degree of conversion. Keywords: Self-etching resin cements; Degree of conversion
http://dx.doi.org/10.1016/j.dental.2014.08.169 http://dx.doi.org/10.1016/j.dental.2014.08.170