Dental Materials Journal 2015; 34(1): 1–6
Effect of agitation and storage temperature on water sorption and solubility of adhesive systems Saryta ARGOLO1, Paula MATHIAS2, Thaiane AGUIAR3, Adriano LIMA4, Sara SANTOS5, Richard FOXTON6 and Andrea CAVALCANTI7 Dentistry Course, Northeast Independent School (FAINOR), Vitoria da Conquista, BA, Brazil School of Dentistry, Federal University of Bahia (FOUFBA), Salvador, BA, Brazil 3 Department of Restorative Dentistry, College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA 4 Department of Restorative Dentistry, State University of Campinas (UNICAMP), Piracicaba, SP, Brazil 5 Private practice, Salvador, BA, Brazil 6 Department of Conservative Dentistry, Kings College London Dental Institute, London, UK 7 Dentistry Course, School of Medicine and Public Health of Bahia (BAHIANA) and School of Dentistry, Federal University of Bahia (FOUFBA), Salvador, BA, Brazil Corresponding author, Saryta ARGOLO; E-mail: [email protected] 1 2
The purpose of this study was to evaluate the influence of storage temperature and flask agitation on the water sorption (WS) and solubility (SL) of simplified adhesive systems. Seventy-two disc-shaped specimens were prepared according to the adhesive system (water/ethanol-based: Adper Single Bond 2; and water-based: One Coat Bond SL) and experimental conditions tested (mechanical agitation and storage temperature). Statistical analysis (3-way ANOVA, alpha=5%) found significantly greater WS and SL means for the water/ethanol-based system when compared to the water-based. Irrespective of factors studied, significant differences in WS and SL were noted between cold and room temperatures, with greater values been obtained at 1°C, and lower ones at 20°C. Agitation provided increased WS for both materials at all temperatures, but did not affect their SL. The mechanical agitation of the flask may negatively affect the dynamics of diffusion of simplified adhesive systems, even at extremely cold or warm temperatures. Keywords: Adhesive systems, Longevity, Sorption, Solubility, Temperature
INTRODUCTION Improvements in the performance of polymeric dental materials has demonstrated important clinical advancements, enabling more conservative preparations and better esthetic outcomes1,2). To achieve long-term success, it is essential to use a safe and durable technique when bonding to dental tissues. Contemporary adhesive systems presents different bonding mechanisms to tooth structure; while the etch and rinse systems act after etching substrates with phosphoric acid; the self-etching systems simultaneously etch and diffuse through enamel or dentin1). Both the etch and rinse and the selfetching agents have simplified versions, with a lower number of steps. Simplifying the adhesive technique may negatively affect the durability of the adhesive bond due to the complexity of the adhesive systems3). Simplified etch and rinse adhesive systems are composed of a mixture of hydrophilic and hydrophobic monomers, solvents, stabilizers, initiators and filler particles2). Increasing the concentration of hydrophilic monomers allows these systems to infiltrate and diffuse into the collagen network, forming a hybrid layer3-8). Hydrophilic systems have an affinity for water, which enables permeation through dentin but may also promote the formation of a polymeric structure more susceptible to hydrolysis4,9). The solvents included in the composition of adhesive systems act in the dissolution of hydrophobic and Received Mar 11, 2014: Accepted May 29, 2014 doi:10.4012/dmj.2014-033 JOI JST.JSTAGE/dmj/2014-033
hydrophilic monomers, and in the displacement of water from the acid etched surfaces, ensuring proper monomer infiltration into the porosities of enamel and dentin8). The commonly used solvents in dental adhesives are water, ethanol and acetone, which vary in accordance to their polarity2). The quality of the hybridization process is highly dependent on the optimal monomer infiltration and on the removal of as much water and organic solvents as possible from the surface prior to curing6). The higher hydrophilicity and possible presence of residual solvent in the simplified adhesive agents means that care is needed to ensure the bonding layer has optimum mechanical properties8). A frequent recommendation is to store the adhesives at room temperature since changes in temperature may influence bonding10). The storage temperature can modify the viscosity of the polymeric material, increasing the penetration capacity, dissolution, time of solvent evaporation and degree of conversion, which might impact on the physical and mechanical properties of the bonding agents11). A continuous brushing or rubbing, or active application of the adhesive system, is also an alternative way of encouraging monomer diffusion and solvent evaporation12). Active application may increase agitation of the molecules, thereby allowing greater evaporation of the solvent and consequently better dispersion and diffusion of monomers through the interface13). Nonetheless, the force applied during active
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Dent Mater J 2015; 34(1): 1–6
application may be relatively difficult to control and standardize. Thus, operator variability is expected when active rubbing of the adhesive system is being conducted. Mechanically agitating the adhesive system bottle can standardize any influence on the wetting ability of the adhesive system, is free of operator variability and regional characteristics of the cavities. However at present, there is still no scientific evidence with respect to the effectiveness of this method. Because the durability of simplified systems is directly related to their permeability, it is important to investigate whether variations in storage temperature and the mode of application may interfere with the gain or loss of the material mass after water exposure. Thus, the aim of this study was to investigate the effect of agitation before application, and of the storage temperature of the flask, on the water sorption and solubility of simplified conventional adhesive systems. The null hypotheses tested were that simplified adhesive systems with different solvents can present similar water sorption and solubility; agitation before application of the adhesive system, and the temperature of the flasks would interfere with the loss or gain of mass.
MATERIALS AND METHODS Specimen preparation and experimental groups Two commercial etch and rinse adhesive systems with distinct chemical compositions were used in this study (Table 1). Both adhesives were categorized as simplified/ etch and rinse, but different types of solvents were present in their composition: ethanol/water-based— Adper Single Bond 2 (3M ESPE); water-based— One Coat Bond SL (Coltène, Vigodent). Both adhesive
systems were evaluated in two different conditions: (1) mechanical agitation or not and (2) storage temperature (1°C, 20°C and 40°C) as illustrated in Fig. 1 Storage temperature of the adhesive system flask The flasks containing the adhesives were stored at experimental temperatures of 1°C (refrigerator temperature), 20°C (room temperature) and 40°C (oven temperature) for 1 h before their application14). These temperatures were verified using a digital thermometer (Omron CO. Inc., Dalian, China). To avoid changes in the temperature of the flask during specimen preparation, the bonding agent was stored in the experimental temperature condition for 1 h and then used again. Mechanical agitation of the flask before application In the case of the groups undergoing mechanical agitation, before each adhesive system application, each respective flask was agitated in a plaster vibrator (VH Equipment Medicos Odontologicos Ltda, Araraquara, SP, Brazil) at a constant speed of 60 Hz/40 W for 20 s. Assessment of loss/gain of mass: Water sorption and solubility The water sorption and solubility test was based on the International Organization for Standardization (ISO) specifications n. 4049:2000 Dentistry –Polymer-based filing, restorative and luting materials15). Seventy-two disc-shaped specimens (6 per group) were prepared (8.0 mm diameter × 1.0 mm thick) using a silicone matrix (Elite HD+, Zhermack, Badia Polesine, Italy) according to the groups to which they belonged. In order to prepare the specimen, three drops of each adhesive were dispensed directly into the matrix
Table 1 Manufacturer, composition and lot number of adhesive systems used in this investigation Adhesive system (Manufacturer)
Composition
Lot number
Adper Single Bond 2 (3M ESPE; St Paul, MN, USA)
Ethanol; water; Bis-GMA; UDMA; silanized silica particles; HEMA; 1-glycerol; 3-dimethacrylate; copolymer of acrylic acid and itaconic acid.
#1119200635
One Coat Bond SL (VIGODENT; Rio de Janeiro, Brazil)
Water; HEMA;hydroxypropyl methacrylate; glycerol dimethacrylate; UDMA; polyalkenoate methacrylate; photoinitiator and inhibitor.
#0175579
Bis-GMA: bisphenol A glycidyl methacrylate; UDMA: di-urethane dimethacrylate; HEMA: 2-hydroxyethyl methacrylate
Fig. 1
Schematic presentation of experimental conditions (n = 6)
3
Dent Mater J 2015; 34(1): 1–6 so that it was completely filled. All visible air bubbles were carefully removed with the aid of a dental explorer probe before light activation. Compressed air from a 3-in-1 syringe spray was used for 10 s at a distance of 20 cm to evaporate the solvent (40-psi air-pressure). A polyester strip and a glass coverslip were placed on the matrix and the surface was then light-activated for 60 s (Radii-Plus, SDI Limited, Australia), taking care that the tip of the light curing unit covered the entire surface of the specimen. The light output of the light curing unit was 1,500 mW/cm2. Afterwards, the specimens were carefully removed from the matrix and the opposing surface was light-activated for additional 60 s16). Immediately after polymerization, the specimens were measured with a digital caliper with an accuracy of 0.01 mm (Mitutoyo Sul Americana Ltda, Suzano, SP, Brazil) in order to calculate the volume (V) of each specimen (mm3). The specimens were stored in a desiccator containing silica gel at 37°C for preconditioning and repeatedly weighed at intervals of 24 h until a constant mass (M1) was obtained (variation of less than 0.2 mg over a period of 24 h). The weighing procedures were performed on an analytical balance (Model AUW-220D, Shimadzu, Kyoto, Japan) with a precision of one hundred-thousandth of a gram. After mass stabilization, the specimens were individually stored in 10 mL of distilled water for 7 days at 37ºC, in accordance to ISO specification. The specimens were kept immersed in a vertical position and water was not changed daily. Afterwards, the specimens were washed under running water and excess water was removed with absorbent paper (Celupa Guaíba Industrial Pulp and Paper Ltd., Guaiba, RS, Brazil). The specimens were weighed and the mass was recorded (M2). After, specimens were dried as previously described and weighed until a constant mass was obtained (M3). The values of water sorption (WS) and solubility (SL) were calculated in µg/mm3 using the following formulas:
WS=
M2−M3 V
SL=
M1−M3 V
Where: M1 is the mass of the sample in μg before immersion in distilled water, M2 is the mass of the sample in μg after immersion in distilled water for 7 days, M3 is the mass of the sample in μg after being reconditioned in a desiccator and V is the volume of the sample (mm3)16). Statistical analysis Initially, an exploratory analysis was carried out to verify the Analysis of Variance parameters (ANOVA). Water sorption and solubility data were statistically analyzed by three-way ANOVA, with main factors adhesive system, agitation and temperature. All possible statistical interactions were included in the model; when interactions were considered as nonsignificant, main factors were analyzed separately. Multiple pairwise comparisons were done with the Tukey post-hoc test (SAS program, version 9.1, at a level of significance of 5%). Tables 2 and 3, show the means and standard deviations for the water sorption and solubility data, respectively.
RESULTS In accordance with the statistical analysis, none interaction between the main factors was considered as significant, neither for water sorption nor for solubility data (p>0.05). For this reason, each main factor (adhesive system, agitation and temperature) was analyzed separately. The analysis of water sorption data indicated that irrespective of the type of adhesive system and flask agitation, significant differences existed between the cold and room temperatures, with greater values obtained at 1oC, and lower ones at 20oC (p=0.04). At 40°C, the results showed intermediate values,
Table 2 Mean values (standard deviation) of water sorption (μg/mm3) of the adhesive systems according to the agitation mode and temperature Agitation
Temperature
Adhesive System
Room (20°C)
Adper Single Bond 2 One Coat Bond SL
247.29 (18.10) a 141.05 (11.95) b
263.06 (25.75) a 155.51 (14.23) b
B
Cold (1°C)
Adper Single Bond 2 One Coat Bond SL
263.80 (10.83) a 158.41 (15.07) b
269.86 (13.41) a 164.78 (6.26) b
A
Warm (40°C)
Adper Single Bond 2 One Coat Bond SL
259.34 (18.84) a 154.33 (12.77) b
262.10 (6.53) a 156.85 (14.00) b
AB
Absent
*
Present
#
Different letters and symbols represent the means with statistical significance (3-way ANOVA, alpha=5%). Different symbols compare the levels of agitation within adhesive system/temperature; capital letters compare the levels of temperature within agitation/adhesive system. Lower case letters compare adhesive systems, irrespective of the temperature or agitation.
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Dent Mater J 2015; 34(1): 1–6
Table 3 Mean values (standard deviation) of solubility (μg/mm3) of the adhesive systems according to the agitation mode and temperature Agitation
Temperature
Adhesive System
Room (20°C)
Adper Single Bond 2 One Coat Bond SL
80.99 (6.39) a 11.68 (0.89) b
78.62 (7.41) a 12.49 (1.90) b
B
Cold (1°C)
Adper Single Bond 2 One Coat Bond SL
79.13 (6.24) a 11.16 (2.02) b
85.98 (3.13) a 13.20 (2.08) b
A
Warm (40°C)
Adper Single Bond 2 One Coat Bond SL
77.92 (6.66) a 11.16 (1.15) b
82.63 (6.48) a 11.25 (1.5) b
AB
Absent
Present
Different letters represent the means with statistical significance (3-way ANOVA, alpha=5%). Capital letters compare the levels of temperature within agitation/adhesive system. Lower case letters compare adhesive systems, irrespective of the temperature or agitation. No significant difference between the levels of agitation was noted.
statistically similar to those at the other temperatures. In addition, agitation resulted in increased water sorption for both adhesive systems at all temperatures tested (p=0.04). Finally, the water-based adhesive system resulted in statistically lower water sorption when compared to the water/ethanol-based agent, at all conditions tested (p
Effect of agitation and storage temperature on water sorption and solubility of adhesive systems Saryta ARGOLO1, Paula MATHIAS2, Thaiane AGUIAR3, Adriano LIMA4, Sara SANTOS5, Richard FOXTON6 and Andrea CAVALCANTI7 Dentistry Course, Northeast Independent School (FAINOR), Vitoria da Conquista, BA, Brazil School of Dentistry, Federal University of Bahia (FOUFBA), Salvador, BA, Brazil 3 Department of Restorative Dentistry, College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA 4 Department of Restorative Dentistry, State University of Campinas (UNICAMP), Piracicaba, SP, Brazil 5 Private practice, Salvador, BA, Brazil 6 Department of Conservative Dentistry, Kings College London Dental Institute, London, UK 7 Dentistry Course, School of Medicine and Public Health of Bahia (BAHIANA) and School of Dentistry, Federal University of Bahia (FOUFBA), Salvador, BA, Brazil Corresponding author, Saryta ARGOLO; E-mail: [email protected] 1 2
The purpose of this study was to evaluate the influence of storage temperature and flask agitation on the water sorption (WS) and solubility (SL) of simplified adhesive systems. Seventy-two disc-shaped specimens were prepared according to the adhesive system (water/ethanol-based: Adper Single Bond 2; and water-based: One Coat Bond SL) and experimental conditions tested (mechanical agitation and storage temperature). Statistical analysis (3-way ANOVA, alpha=5%) found significantly greater WS and SL means for the water/ethanol-based system when compared to the water-based. Irrespective of factors studied, significant differences in WS and SL were noted between cold and room temperatures, with greater values been obtained at 1°C, and lower ones at 20°C. Agitation provided increased WS for both materials at all temperatures, but did not affect their SL. The mechanical agitation of the flask may negatively affect the dynamics of diffusion of simplified adhesive systems, even at extremely cold or warm temperatures. Keywords: Adhesive systems, Longevity, Sorption, Solubility, Temperature
INTRODUCTION Improvements in the performance of polymeric dental materials has demonstrated important clinical advancements, enabling more conservative preparations and better esthetic outcomes1,2). To achieve long-term success, it is essential to use a safe and durable technique when bonding to dental tissues. Contemporary adhesive systems presents different bonding mechanisms to tooth structure; while the etch and rinse systems act after etching substrates with phosphoric acid; the self-etching systems simultaneously etch and diffuse through enamel or dentin1). Both the etch and rinse and the selfetching agents have simplified versions, with a lower number of steps. Simplifying the adhesive technique may negatively affect the durability of the adhesive bond due to the complexity of the adhesive systems3). Simplified etch and rinse adhesive systems are composed of a mixture of hydrophilic and hydrophobic monomers, solvents, stabilizers, initiators and filler particles2). Increasing the concentration of hydrophilic monomers allows these systems to infiltrate and diffuse into the collagen network, forming a hybrid layer3-8). Hydrophilic systems have an affinity for water, which enables permeation through dentin but may also promote the formation of a polymeric structure more susceptible to hydrolysis4,9). The solvents included in the composition of adhesive systems act in the dissolution of hydrophobic and Received Mar 11, 2014: Accepted May 29, 2014 doi:10.4012/dmj.2014-033 JOI JST.JSTAGE/dmj/2014-033
hydrophilic monomers, and in the displacement of water from the acid etched surfaces, ensuring proper monomer infiltration into the porosities of enamel and dentin8). The commonly used solvents in dental adhesives are water, ethanol and acetone, which vary in accordance to their polarity2). The quality of the hybridization process is highly dependent on the optimal monomer infiltration and on the removal of as much water and organic solvents as possible from the surface prior to curing6). The higher hydrophilicity and possible presence of residual solvent in the simplified adhesive agents means that care is needed to ensure the bonding layer has optimum mechanical properties8). A frequent recommendation is to store the adhesives at room temperature since changes in temperature may influence bonding10). The storage temperature can modify the viscosity of the polymeric material, increasing the penetration capacity, dissolution, time of solvent evaporation and degree of conversion, which might impact on the physical and mechanical properties of the bonding agents11). A continuous brushing or rubbing, or active application of the adhesive system, is also an alternative way of encouraging monomer diffusion and solvent evaporation12). Active application may increase agitation of the molecules, thereby allowing greater evaporation of the solvent and consequently better dispersion and diffusion of monomers through the interface13). Nonetheless, the force applied during active
2
Dent Mater J 2015; 34(1): 1–6
application may be relatively difficult to control and standardize. Thus, operator variability is expected when active rubbing of the adhesive system is being conducted. Mechanically agitating the adhesive system bottle can standardize any influence on the wetting ability of the adhesive system, is free of operator variability and regional characteristics of the cavities. However at present, there is still no scientific evidence with respect to the effectiveness of this method. Because the durability of simplified systems is directly related to their permeability, it is important to investigate whether variations in storage temperature and the mode of application may interfere with the gain or loss of the material mass after water exposure. Thus, the aim of this study was to investigate the effect of agitation before application, and of the storage temperature of the flask, on the water sorption and solubility of simplified conventional adhesive systems. The null hypotheses tested were that simplified adhesive systems with different solvents can present similar water sorption and solubility; agitation before application of the adhesive system, and the temperature of the flasks would interfere with the loss or gain of mass.
MATERIALS AND METHODS Specimen preparation and experimental groups Two commercial etch and rinse adhesive systems with distinct chemical compositions were used in this study (Table 1). Both adhesives were categorized as simplified/ etch and rinse, but different types of solvents were present in their composition: ethanol/water-based— Adper Single Bond 2 (3M ESPE); water-based— One Coat Bond SL (Coltène, Vigodent). Both adhesive
systems were evaluated in two different conditions: (1) mechanical agitation or not and (2) storage temperature (1°C, 20°C and 40°C) as illustrated in Fig. 1 Storage temperature of the adhesive system flask The flasks containing the adhesives were stored at experimental temperatures of 1°C (refrigerator temperature), 20°C (room temperature) and 40°C (oven temperature) for 1 h before their application14). These temperatures were verified using a digital thermometer (Omron CO. Inc., Dalian, China). To avoid changes in the temperature of the flask during specimen preparation, the bonding agent was stored in the experimental temperature condition for 1 h and then used again. Mechanical agitation of the flask before application In the case of the groups undergoing mechanical agitation, before each adhesive system application, each respective flask was agitated in a plaster vibrator (VH Equipment Medicos Odontologicos Ltda, Araraquara, SP, Brazil) at a constant speed of 60 Hz/40 W for 20 s. Assessment of loss/gain of mass: Water sorption and solubility The water sorption and solubility test was based on the International Organization for Standardization (ISO) specifications n. 4049:2000 Dentistry –Polymer-based filing, restorative and luting materials15). Seventy-two disc-shaped specimens (6 per group) were prepared (8.0 mm diameter × 1.0 mm thick) using a silicone matrix (Elite HD+, Zhermack, Badia Polesine, Italy) according to the groups to which they belonged. In order to prepare the specimen, three drops of each adhesive were dispensed directly into the matrix
Table 1 Manufacturer, composition and lot number of adhesive systems used in this investigation Adhesive system (Manufacturer)
Composition
Lot number
Adper Single Bond 2 (3M ESPE; St Paul, MN, USA)
Ethanol; water; Bis-GMA; UDMA; silanized silica particles; HEMA; 1-glycerol; 3-dimethacrylate; copolymer of acrylic acid and itaconic acid.
#1119200635
One Coat Bond SL (VIGODENT; Rio de Janeiro, Brazil)
Water; HEMA;hydroxypropyl methacrylate; glycerol dimethacrylate; UDMA; polyalkenoate methacrylate; photoinitiator and inhibitor.
#0175579
Bis-GMA: bisphenol A glycidyl methacrylate; UDMA: di-urethane dimethacrylate; HEMA: 2-hydroxyethyl methacrylate
Fig. 1
Schematic presentation of experimental conditions (n = 6)
3
Dent Mater J 2015; 34(1): 1–6 so that it was completely filled. All visible air bubbles were carefully removed with the aid of a dental explorer probe before light activation. Compressed air from a 3-in-1 syringe spray was used for 10 s at a distance of 20 cm to evaporate the solvent (40-psi air-pressure). A polyester strip and a glass coverslip were placed on the matrix and the surface was then light-activated for 60 s (Radii-Plus, SDI Limited, Australia), taking care that the tip of the light curing unit covered the entire surface of the specimen. The light output of the light curing unit was 1,500 mW/cm2. Afterwards, the specimens were carefully removed from the matrix and the opposing surface was light-activated for additional 60 s16). Immediately after polymerization, the specimens were measured with a digital caliper with an accuracy of 0.01 mm (Mitutoyo Sul Americana Ltda, Suzano, SP, Brazil) in order to calculate the volume (V) of each specimen (mm3). The specimens were stored in a desiccator containing silica gel at 37°C for preconditioning and repeatedly weighed at intervals of 24 h until a constant mass (M1) was obtained (variation of less than 0.2 mg over a period of 24 h). The weighing procedures were performed on an analytical balance (Model AUW-220D, Shimadzu, Kyoto, Japan) with a precision of one hundred-thousandth of a gram. After mass stabilization, the specimens were individually stored in 10 mL of distilled water for 7 days at 37ºC, in accordance to ISO specification. The specimens were kept immersed in a vertical position and water was not changed daily. Afterwards, the specimens were washed under running water and excess water was removed with absorbent paper (Celupa Guaíba Industrial Pulp and Paper Ltd., Guaiba, RS, Brazil). The specimens were weighed and the mass was recorded (M2). After, specimens were dried as previously described and weighed until a constant mass was obtained (M3). The values of water sorption (WS) and solubility (SL) were calculated in µg/mm3 using the following formulas:
WS=
M2−M3 V
SL=
M1−M3 V
Where: M1 is the mass of the sample in μg before immersion in distilled water, M2 is the mass of the sample in μg after immersion in distilled water for 7 days, M3 is the mass of the sample in μg after being reconditioned in a desiccator and V is the volume of the sample (mm3)16). Statistical analysis Initially, an exploratory analysis was carried out to verify the Analysis of Variance parameters (ANOVA). Water sorption and solubility data were statistically analyzed by three-way ANOVA, with main factors adhesive system, agitation and temperature. All possible statistical interactions were included in the model; when interactions were considered as nonsignificant, main factors were analyzed separately. Multiple pairwise comparisons were done with the Tukey post-hoc test (SAS program, version 9.1, at a level of significance of 5%). Tables 2 and 3, show the means and standard deviations for the water sorption and solubility data, respectively.
RESULTS In accordance with the statistical analysis, none interaction between the main factors was considered as significant, neither for water sorption nor for solubility data (p>0.05). For this reason, each main factor (adhesive system, agitation and temperature) was analyzed separately. The analysis of water sorption data indicated that irrespective of the type of adhesive system and flask agitation, significant differences existed between the cold and room temperatures, with greater values obtained at 1oC, and lower ones at 20oC (p=0.04). At 40°C, the results showed intermediate values,
Table 2 Mean values (standard deviation) of water sorption (μg/mm3) of the adhesive systems according to the agitation mode and temperature Agitation
Temperature
Adhesive System
Room (20°C)
Adper Single Bond 2 One Coat Bond SL
247.29 (18.10) a 141.05 (11.95) b
263.06 (25.75) a 155.51 (14.23) b
B
Cold (1°C)
Adper Single Bond 2 One Coat Bond SL
263.80 (10.83) a 158.41 (15.07) b
269.86 (13.41) a 164.78 (6.26) b
A
Warm (40°C)
Adper Single Bond 2 One Coat Bond SL
259.34 (18.84) a 154.33 (12.77) b
262.10 (6.53) a 156.85 (14.00) b
AB
Absent
*
Present
#
Different letters and symbols represent the means with statistical significance (3-way ANOVA, alpha=5%). Different symbols compare the levels of agitation within adhesive system/temperature; capital letters compare the levels of temperature within agitation/adhesive system. Lower case letters compare adhesive systems, irrespective of the temperature or agitation.
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Dent Mater J 2015; 34(1): 1–6
Table 3 Mean values (standard deviation) of solubility (μg/mm3) of the adhesive systems according to the agitation mode and temperature Agitation
Temperature
Adhesive System
Room (20°C)
Adper Single Bond 2 One Coat Bond SL
80.99 (6.39) a 11.68 (0.89) b
78.62 (7.41) a 12.49 (1.90) b
B
Cold (1°C)
Adper Single Bond 2 One Coat Bond SL
79.13 (6.24) a 11.16 (2.02) b
85.98 (3.13) a 13.20 (2.08) b
A
Warm (40°C)
Adper Single Bond 2 One Coat Bond SL
77.92 (6.66) a 11.16 (1.15) b
82.63 (6.48) a 11.25 (1.5) b
AB
Absent
Present
Different letters represent the means with statistical significance (3-way ANOVA, alpha=5%). Capital letters compare the levels of temperature within agitation/adhesive system. Lower case letters compare adhesive systems, irrespective of the temperature or agitation. No significant difference between the levels of agitation was noted.
statistically similar to those at the other temperatures. In addition, agitation resulted in increased water sorption for both adhesive systems at all temperatures tested (p=0.04). Finally, the water-based adhesive system resulted in statistically lower water sorption when compared to the water/ethanol-based agent, at all conditions tested (p
