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PubMed1996

Comparative shear bond strength of some orthodontic bonding resins to enamel.

The aim of this study was to compare the in vitro bond strength, to bovine enamel measured in shear, of the orthodontic adhesives Lee Insta-bond (LiB), Rely-a-Bond (RaB), Right-on (Ro), Concise precoating method (Cc), Concise mixed method (CaB), Super-C (Sc), and Orthon (Or), and of the glass ionomer cement Ketac-Cem (KC). The fracture surfaces after debonding were also examined in order to determine the sites of failure. The results indicate that there is a significant difference between the shear bond strength obtained with the different adhesives so that the mean shear bond strength decreases in the order [Ro approximately Cab approximately Sc] > [LiB approximately RaB approximately Cc] > Or > KC. Moreover, for Cab and Sc it was found that the shear bond strength varies depending on the location on the bovine tooth. The failure site was essentially at the resin-bracket interface, except for Concise, where only 50 per cent of the cases failed at the resin-bracket interface.

Adhesives↗
PubMed1994

[The comparison of shear bond strength of orthodontic brackets to bovine enamel pretreated by different conditions of Nd-YAG laser].

Laser beams can cause the enamel surface roughly which is similar to the effect of the traditional acid-etching technique. We wanted to study the possibility of the application of the laser on enamel etching. In this study we treated the enamel with different energy levels for orthodontic bracket placement and measuring the shear bond strength. 104 bovine teeth were polished by 600 # grit sandpaper, then cut, embedded, set and divided into 13 groups. The control group was not treated. 12 different energy levels (10pps 50, 70, 85, 100mJ; 15pps 83.3mJ; 20pps 50, 87.5, 100, 150mJ; 30pps 50, 86.7, 100mJ) were treated on the enamel. The orthodontic brackets were placed on 8 specimens of each group with orthodontic resin (Ormco). Then, the specimens were put in 37 degrees C water bath for 24 hours. 7 specimens of the control group of brackets fell off after water bath. The shear forces of the other 97 specimens were measured by the Instron at a crosshead speed of 0.5 mm/min. The shear strength of the only one specimen of the control group was 0.1MPa. The results for the range of shear strength of the laser group were 2.66-5.53MPa. The shear strength increased proportionately to the energy density. Because the mean shear strength of the laser group were significantly high, we can refer the practical application in orthodontic clinic. The laser beam only affected the area coated with Chinese ink, so the treated area is controllable. The fracture surface of the laser-etched was smooth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Shear bond strength of dental porcelains to nickel-chromium alloys.

The continuous technological advance and increasing availability of new base metal alloys and ceramic systems in the market, coupled to the demands of daily clinical practice, have made the constant evaluation of the bond strength of metal/porcelain combinations necessary. This study evaluated the metal/porcelain shear bond strength of three ceramic systems (Duceram, Williams and Noritake) in combination with three nickel-chromium (Ni-Cr) alloys (Durabond, Verabond and Viron). Thirty cast cylinder specimens (15 mm high; 6 mm in diameter) were obtained for each alloy, in a way that 10 specimens of each alloy were tested with each porcelain. Bond strength was measured with an Emic screw-driven mechanical testing machine by applying parallel shear forces to the specimens until fracture. Shear strength was calculated using the ratio of the force applied to a demarcated area of the opaque layer. Mann-Whitney U test was used for statistical analysis of the alloy/ceramic combinations (p<0.05). Viron/Noritake had the highest shear bond sregnth means (32.93 MPa), while Verabond/Duceram (16.31 MPa) presented the lowest means. Viron/Noritake differed statistically from other combinations (p<0.05). Viron/Duceram had statistically significant higher bond strengths than Verabond/Duceram, Verabond/Williams and Durabond/Noritake (p<0.05). It was also found significant difference (p<0.05) between Verabond/Noritake, Verabond/Duceram and Durabond/Noritake. No statistically significant difference (p>0.05) were observed among the other combinations. In conclusion, the Noritake ceramic system used together with Viron alloy presented the highest resistance to shear forces, while Duceram bonded to Verabond presented the lowest bond strength. Viron/Duceram and Verabond/Noritake provided intermediate results. The combinations between the Williams ceramic system and Ni-Cr alloys had similar shear strengths among each other.

Aluminum Oxide↗
PubMed2000

[Effects of pulsed Nd:YAG laser irradiation on shear bond strength of composite resin bonded to porcelain].

OBJECTIVE: To evaluate the shear bond strength of composite resin bonded to pretreated porcelain surfaces by use of a pulsed Nd:YAG laser irradiation and by use of 8% hydrofluoric etching. METHODS: Surfaces of porcelain were roughened with coarse diamonds until the opaque body porcelains were exposed. The samples were divided into four groups. Samples of the first group were etched with 8% hydrofluoric acid for 3 min by following the manufacter's instructions. Samples of the 2nd, 3rd and 4th groups were separately irradiated by a pulsed Nd:YAG laser of three energy parameters of 15 Hz, 40 mJ; 0.6 W; 15 Hz, 60 mJ, 0.9 W and 15 Hz, 80 mJ, 1.2 W different respectively, each specimen was irradiated for 1 min. Then, silane coupling agent was equally placed on the treated surfaces for 3 min, the activator was used on each surface. The adhesive was applied and light-cured. The composite resin material was finally bonded to the treated porcelain surface, forming a 3 mm x 3 mm x 2 mm resin mass. Samples were then tested for shear bond strength between the treated porcelain and composite resin by using a SWD-10 electric universal testing machine with a crosshead speed of 1 mm/min until fracture. At the end of testing, the data was evaluated by using a two-way analysis of variance (ANOVA) comparing the shear bond strength. On the other hand, characteristic morphology of laser irradiated surfaces of porcelain was prepared and observed by a scanning electron microscopy. RESULTS: The shear bond strength of laser groups of 0.6 W, 0.9 W, 1.2 W and etching group was respectively 8.61, 14.07, 11.22 and 13.47 MPa. There was no significantly difference among groups of laser 0.9 W, 1.2 W and the etching group. This suggested that irradiated on surfaces of porcelain by Nd:YAG laser at the above laser energy could attain the same effectiveness as hydrofluoric acid etching. But the shear bond strength of laser 0.6 W group was significantly lower than the etching group. It suggested that shear bond strength would obviously decrease when laser energy was 0.6 W or lower than this parameter, and had no use in treatment on porcelain surfaces comparing to acid etching. SEM showed that porcelain surfaces irradiated by Nd:YAG laser exhibited rough, umbilicate, lava crater-like structure. This structure helped to produce mechanical retention between resin composite and porcelain. CONCLUSION: The pulsed Nd:YAG laser could replace etching method to pretreat the fracture porcelain surfaces for bonding with composite resin at appropriate energy parameters.

Composite Resins↗
PubMed1994

A comparative study of the shear bond strengths of four different crystal growth solutions.

Previously, solutions based on polyacrylic acid have been found to initiate crystal growth on the enamel surface. Such crystals have been proposed as being suitable for the attachment of orthodontic brackets via a conventional composite interface, the advantages being improved clean-up characteristics and reduced damage to the enamel. In order to try and improve the reliability of the technique this base solution has been modified by the authors, by the addition of various ionic salts. The strength of the resultant bond was assessed for the base solution of 50 per cent polyacrylic acid and concentrated sulphuric, and for three more solutions modified by the addition of the sulphates of lithium, magnesium, and potassium, respectively. A standard acid/etch method of bracket attachment was also included for the purposes of comparison. The bond strength of each material was assessed by shear testing, performed on human extracted premolar teeth to a standard method. As might have been expected the acid/etch system proved to be the strongest method of bonding brackets. Amongst the crystal solutions, the addition of lithium sulphate provided the highest mean shear strength at 80 per cent of that for acid etch. Therefore, this latter solution provides the most potential for development in the future.

Acid Etching, Dental↗
PubMed2000

Shear bond strength of resin teeth to heat-cured and light-cured denture base resin.

The failure of the bond between acrylic resin teeth and denture base material remains a considerable problem. Previous research has indicated that the introduction of a bonding agent to the tooth-resin interface significantly increased the tensile bond strength. To further investigate this finding, and to complement the earlier study, a shear strength assessment was carried out. Both a commercial and an experimental bonding agent were evaluated for tooth retention when applied to heat-cured and visible light-cured (VLC) resin. A significant increase in shear bond strength was obtained when bonding agents were applied. The experimental cement gave the greatest increase in strength, although the VLC resin failed to achieve the same degree of tooth attachment as the heat-cured resin.

Acrylic Resins↗
PubMed1999

Amalgam shear bond strength to dentin using single-bottle primer/adhesive systems.

PURPOSE: To evaluate the in vitro shear bond strengths (SBS) of a spherical amalgam alloy (Tytin) to dentin using several single-bottle primer/adhesive systems both alone: Single Bond (SB), OptiBond Solo (Sol), Prime & Bond 2.1 (PB), One-Step (OS) and in combination with the manufacturer's supplemental amalgam bonding agent: Single Bond w/3M RelyX ARC (SBX) and Prime & Bond 2.1 w/Amalgam Bonding Accessory Kit (PBA). Two, three-component adhesive systems, Scotchbond Multi-Purpose (SBMP) and Scotchbond Multi-Purpose Plus w/light curing (S + V) and w/o light curing (S+) were used for comparison. MATERIALS AND METHODS: One hundred eight extracted human third molars were mounted lengthwise in phenolic rings with acrylic resin. The proximal surfaces were ground to expose a flat dentin surface, then polished to 600 grit silicon carbide paper. The teeth were randomly assigned to 9 groups (n = 12), and dentin surfaces in each group were treated with an adhesive system according to the manufacturer's instructions, except for S + V specimens, where the adhesive was light cured for 10 s before placing the amalgam. Specimens were then secured in a split Teflon mold, having a 3 mm diameter opening and amalgam was triturated and condensed onto the treated dentin surfaces. Twenty minutes after condensation, the split mold was separated. Specimens were placed in distilled water for 24 hrs, then thermocycled (300 cycles, between 5 degrees C and 55 degrees C, with 12 s dwell time). All specimens were stored in 37 degrees C distilled water for 7 days, prior to shear strength testing using a Zwick Universal Testing Machine at a cross-head speed of 0.5 mm/min. RESULTS: The highest to the lowest mean dentin shear bond strength values (MPa) for the adhesive systems tested were: S + V (10.3 +/- 2.3), SBX (10.2 +/- 3.5), PBA, (6.4 +/- 3.6), SOL (5.8 +/- 2.5), SBMP (5.7 +/- 1.8), S+ (4.8 +/- 2.3), PB (2.7 +/- 2.6), SB (2.7 +/- 1.1) and OS (2.5 +/- 1.8). One-way ANOVA and Duncan's Multiple Range Test indicated significant differences among groups. SBX and S + V produced significantly higher amalgam to dentin shear bond strengths than all other adhesive systems. Bond strengths of amalgam to dentin for the single-bottle adhesives, SOL and PBA were comparable to the three-component systems, SBMP and S+ and were significantly greater than OS, SB and PB (P < 0.05).

Analysis of Variance↗
PubMed1998

Effect of primer solvent, primer agitation, and dentin dryness on shear bond strength to dentin.

PURPOSE: To evaluate the shear bond strength of acetone- or water-based primers applied with or without agitation to either wet or dry dentin. MATERIALS AND METHODS: Forty-eight caries-free extracted human premolars were embedded in gypsum and flat dentin surfaces were prepared. The teeth were randomly divided in eight groups with six specimens each. After acid etching and rinsing, either a HEMA and acetone (Ac) or a HEMA and water (Wa) primer were applied to dry (D) or wet (W) dentin. The primer was placed with (Y) or without (N) agitation according to the following combinations: Group 1: D-Ac-Y; Group 2: D-Ac-N; Group 3: D-Wa-Y; Group 4: D-Wa-N; Group 5: W-Ac-Y; Group 6: W-Ac-N; Group 7: W-Wa-Y; Group 8: W-Wa-N. The primed surface was dried, covered with a bonding resin and light-cured, whereupon a composite cylinder was bonded to the dentin surface. The shear bond strength was determined after 30 days in water. RESULTS: The mean and standard deviations, expressed in MPa, were: Group 1: 13.1 +/- 3.42; Group 2: 15.9 +/- 4.84; Group 3: 19.8 +/- 6.64; Group 4: 18.6 +/- 5.18; Group 5: 16.5 +/- 5.25; Group 6: 25.5 +/- 4.79; Group 7: 21.9 +/- 4.94; Group 8: 17.4 +/- 4.50. The results were analyzed using ANOVA and Waller-Duncans K-ratio t-test. The acetone-based primer gave the highest bond strength to wet dentin without agitation. When the acetone-based primer was used on dry dentin a significant decrease in bond strength occurred (P < 0.05). No significant difference (P > 0.05) was found for the water-based primer on wet or dry dentin. Agitation improved the bond strength for the water-based primer, but decreased the bond strength for the acetone-based primer.

Acetone↗
PubMed1990

Shear bond strength and SEM evaluation of dentinal bonding systems.

Shear bond strength of seven dentin bonding systems (DBS) was evaluated. After shear bond testing, the specimens were analyzed under scanning electron microscope (SEM). Buccal dentin just below the dentin-enamel junction of erupted third molars of young subjects were used. A statistical difference was observed among the material bond values. SEM examination of both sides of the sheared bonds frequently showed an adhesive failure between dentin and bonding agents in the specimens where resin penetrated into the opened dentinal tubules. A complex cohesive fracture of both resin and dentin was observed for bonding agents that required the treatment of the smear layer, while a cohesive fracture in the smear layer thickness was noted when dentin was not altered by primer solutions. The study demonstrated that the DBS that require the removal of the smear layer showed a significantly higher shear bond strength and that the bond value reflects the mode of material fracture and the presence of smear layer.

Composite Resins↗
PubMed2001

Shear bond strength of six restorative materials.

The purpose of this study was to determine and compare the shear bond strength of a conventional glass-ionomer cement, a resin modified glass-ionomer, a composite resin and three compomer restorative materials. Dentin of the occlusal surfaces from sixty extracted human permanent molars were prepared for shear bond strength testing. The specimens were randomly divided into six groups of 10 each. Dentinal surfaces were treated according to the instructions of manufacturers for each material. Each restorative material was placed inside nylon cylinders 2 mm high with an internal diameter of 3 mm, which were placed perpendicular to dentin surfaces. Shear bond strengths were determined using an Universal Testing Machine at crosshead speed of 0.5 mm/min in a compression mode. Conventional glass-ionomer, Ketac-Molar aplicap showed the lowest mean shear bond strength 3.77+/-1.76 (X +/- SD MPa) and the composite resin, Heliomolar showed the highest mean shear bond strength 16.54+/-1.65 while the mean bond strength of Fuji II LC was 9.55+/-1.06. The shear bond strengths of compomer restorative materials were 12.83+/-1.42, 10.64+/-1.42 and 11.19+/-1.19 for Compoglass, Hytac and Dyract respectively. ANOVA revealed statistically significant differences in the mean shear bond strengths of all groups (P<0.001). No statistically significant difference was found between the three compomer materials (P>0.5). Ketac-Molar and composite resin showed statistically significant difference (P<0.0005). The mode of fracture varied between materials. It is concluded that the compomer restorative materials show higher shear bond strength than conventional glass-ionomer and resin modified glass-ionomer, but less than composite resin. The fracture mode is not related to the shear bond strengths values.

Acid Etching, Dental↗
PubMed2006

Shear bond strength of metal brackets on enamel.

OBJECTIVE: To compare the shear bond strength of different metal orthodontic brackets. MATERIALS AND METHODS: Five types of orthodontic metal brackets were selected (S1, Victory Series, 3M Unitek, Monrovia, Calif; S2, Mini Dyna-Lock, 3M Unitek; S3, Mini Sprint, Forestadent, Pforzheim, Germany; S4, Topic, Dentaurum, Inspringen, Germany; and S5, equilibrium 2, Dentaurum). Brackets were bonded on enamel surfaces of bovine incisors (Transbond XT, 3M Unitek) and were tested for shear bond strength with an Instron universal testing machine (Instron Corp, Canton, Mass). Data obtained in newtons and megapascals were analyzed with descriptive statistics and with analysis of variance and Tukey honestly significant difference (HSD) tests. The adhesive fracture site was classified with the adhesive remnant index (ARI). RESULTS: All the specimens tested had shear bond strength adequate to resist orthodontic forces. S5 showed significantly greater bond strength when compared with the other samples, except for S1. S1, S3, and S5 showed a significantly greater bonding force. The ARI index demonstrated a large variability. Retentive structure of S1, S3, and S5 had equal validity. The enlargement of the retentive surface enhances adhesion but affects the adaptability to surface irregularity of the enamel, increasing the risk of fracture at the interface with the bracket. CONCLUSIONS: The results of this study suggest that probably the retentive base extension can be lower than 7 mm2 proposed in previous studies as the minimal area.

Acid Etching, Dental↗
PubMed1996

Shear bond strength of a new polycarbonate bracket--an in vitro study with 14 adhesives.

Shear bond strength and failure location were used to evaluate the effectiveness of plastic bracket primers for bonding diacrylate adhesives on a new fibre-reinforced polycarbonate bracket. Maxillary incisor polycarbonate and mesh-based brackets as control were bonded to human incisors with 14 different adhesives (four filled diacrylate two-paste, six diacrylate one-step and four power-liquid acrylic adhesives), and after thermo-cycling for 2000 cycles between 5 degrees and 55 degrees C, tested in shear. A non-parametric test (Mann-Whitney U test) was used to compare the shear bond strength of the polycarbonate brackets with the mesh based brackets and a One-way test (according to Scheffe) to compare the shear bond strength of different adhesives. The following conclusions can be made: 1. Seven of the 14 adhesives used in this study with both types of brackets demonstrated adequate shear bond strength values for the clinical application. The exceptions were: Achieve Mix, No-Mix:30 Silkon, Lee Insta-Bond, Ortho-Loc and Bond-Eze, all with too low a shear bond strength for one or both types of brackets, and finally Quasar, which used with the plastic brackets sometimes caused enamel fractures, due to high bond strength. 2. The adhesives with their own plastic primer demonstrated higher blood strength values than those without plastic primer, and two-paste adhesives used with plastic primer displayed a higher bond strength than the other adhesives. 3. Generally, the shear bond strength values of the one-step adhesives were lower compared with the two-paste adhesives. 4. The liquid-powder adhesives demonstrated very different values for bond strength.

Composite Resins↗
PubMed1980

Shear bond strength in porcelain-metal restorations.

1. The push test method showed higher shear bond strength values than the pull test method. 2. A bond strength of 4,500 to 6,000 psi between the dental stone and metal rod was eliminated in a waxed-rod test. Although the strength values were lower in waxed-rod tests, they were believed to be true shear bond strength values. 3. Shear bond strengths of 12,000 psi in push tests and 9,700 psi in pull tests were observed in Ceramco porcelain fused to Ceramco gold.

Adhesiveness↗
PubMed1987

Optimum pore size for bone cement fixation.

The interface shear properties of porous coated Ti-6Al-4V alloy embedded in bone cement were examined as a function of pore size. Cylindric Ti-6Al-4V alloy push-out specimens were coated with two layers of spheric powders having particle size ranges of 297-420 microns, 420-500 microns, 595-707 microns, and 850-1400 microns. Sintering resulted in mean pore sizes of 165, 285, 345, and 550 microns, respectively, and porosities in the range of 40%-44%. There was a statistically significant difference between the mean pore sizes obtained from the four particle size ranges. There were no differences between the mean porosities. The porous-coated specimens were embedded in bone cement and mechanical push-out testing was performed. Non-coated specimens having a satin surface finish were also embedded in bone cement and tested. The noncoated metal specimens displayed an interface shear strength of 4.2 +/- 0.4 MPa, whereas the shear strengths for the porous-coated specimens were significantly higher and increased as pore size increased. The mean interface shear strengths determined were 17.0 +/- 2.1 MPa (165 microns pore size), 18.1 +/- 2.3 MPa (285 micron pore size), 23.6 +/- 1.7 MPa (345 microns pore size), and 25.4 +/- 3.4 MPa (550 microns pore size). Significant differences in shear strength for the porous-coated specimens were found between the two smaller particle sizes and the two larger particle sizes. As pore size increased from 285 microns to 345 microns, a statistically significant increase in shear strength from 18.1 MPa to 23.6 MPa was observed.

Alloys↗
PubMed2006

Shear bond strength of acetone-based one-bottle adhesive systems.

The aim of this study was to assess the shear bond strength of four acetone-based one-bottle adhesive systems to enamel and dentin, and compare to that of an ethanol-based system used as control. Fifty human molars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin using PVC cylinders. The buccal surfaces were ground to obtain flat dentin surfaces, while the lingual surfaces were ground to obtain flat enamel surfaces. All specimens were polished up to 600-grit sandpapers and randomly assigned to 5 groups (n=20; 10 dentin specimens and 10 enamel specimens), according to the adhesive system used: One-Step (Bisco); Gluma One Bond (Heraeus Kulzer); Solobond M (Voco); TenureQuik w/F (Den-Mat) and OptiBond Solo Plus (Kerr) (control). Each adhesive system was applied according to the manufacturers' instructions. The respective proprietary hybrid composite was applied in a gelatin capsule (d=4.3 mm) and light-cured for 40 s. The specimens were tested in shear strength with an Instron machine at a crosshead speed of 5 mm/min. Bond strengths means were analyzed statistically by one-way ANOVA and Duncan's post-hoc (p< or =0.05). Shear bond strength means (MPa) (+/-SD) to enamel and dentin were: Enamel: One-Step=11.3(+/-4.9); Gluma One Bond=16.3(+/-10.1); Solobond M=18.9(+/-4.5); TenureQuik w/F=18.7(+/-4.5) and OptiBond Solo Plus=16.4(+/-3.9); Dentin: One-Step=6.4(+/-2.8); Gluma One Bond=3.0(+/-3.4); Solobond M=10.6(+/-4.9); TenureQuik w/F=7.8(+/-3.9) and OptiBond Solo Plus=15.1(+/-8.9). In enamel, the adhesive systems had statistically similar bond strengths to each other (p>0.05). However, the ethanol-based system (OptiBond Solo Plus) showed significantly higher bond strength to dentin than the acetone-based systems (p< or =0.0001). In conclusion, the solvent type (acetone or ethanol) had no influence on enamel bond strength, but had great influence on dentin bonding, which should be taken into account when choosing the adhesive system.

Acetone↗
PubMed2001

Influence of cross-head speed on resin-dentin shear bond strength.

OBJECTIVE: To evaluate the influence of different cross-head speeds on shear bond strength test on the dentin surface. METHODS: One hundred and twenty extracted bovine incisors were embedded in polystyrene resin. The specimens were prepared by wet grinding with 320-, 400- and 600-grit Al2O3 paper exposing dentin. After the application of the adhesive system Single Bond (3M) to etched dentin, the composite resin Z-100 (3M) was applied and light cured. The specimens were randomly assigned to four groups (n=30). The shear bond strength tests were performed with an EMIC DL 500 universal testing machine at four different cross-head speeds: 0.50 (A); 0.75 (B); 1.00 (C); and 5.00 mm/min (D). RESULTS: The mean values of shear bond strength in MPa (SD) were: A, 11.78 (3.91); B, 11.82 (4.78); C, 16.32 (6.45); D, 15.46 (5.94). The data were analyzed with one-way ANOVA and Tukey's test (alpha=0.05). The results indicated that A=B<C=D. The fracture pattern was evaluated by visual analysis in a stereomicroscope (25x). The percentage of fractures that occurred at the adhesive interface were: A, 92.5%; B, 91.6%; C, 70.0%; D, 47.0%. The Student's t-test to percentages (alpha=0.05) indicated that there were no significant differences among A, B and C; A and B differed from D, and there was no significant difference between C and D. SIGNIFICANCE: Different cross-head speeds may influence the shear bond strength and the fracture pattern in dentin substrate. Shear bond strength using cross-head speeds of 0.50 and 0.75 mm/min should be preferred.

Acid Etching, Dental↗
PubMedDate not supplied

Shear bond strength of composite resin to fresh amalgam.

The shear bond strength between fresh amalgam and composite resin using three adhesive systems was assessed. Amalgambond (5.19 MPa), All-Bond (3.45 MPa), and Clearfil New-Bond (4.37 MPa) had comparable shear bond strengths higher than Enamel Bond (1.27 MPa) after 48 hours of water immersion. This bond was hydrolytically degraded during 100 days of immersion in water. The greatest deterioration was observed for Clearfil New-Bond (0.81 MPa). Amalgambond provided the best results, whereas All-Bond and Clearfil New-Bond had comparable bond strength to Enamel Bond at the end of the experiment.

Analysis of Variance↗
PubMedDate not supplied

Effect of placement agitation and placement time on the shear bond strength of 3 self-etching adhesives.

This study measured the shear bond strength (SBS) of 3 self-etching bonding agents to enamel and dentin with and without agitation at 3 different application times. The null hypotheses tested were that agitation and application time have no effect on bond strength. Occlusal surfaces of 180 recently extracted caries-free human molars were wet ground with 600 grit wet-dry silica carbide abrasive paper to obtain a flat enamel surface. The teeth were divided into 18 groups of 10 teeth. Three self-etching bonding agents, Clearfil SE BOND (Kuraray America), Xeno III (Dentsply) and AdheSE (Ivoclar-Vivadent) were applied using application times of 10, 20 or 30 seconds with or without agitation, thinned with a gentle stream of air and cured for 10 seconds, according to manufacturers' directions. Z100 (3M ESPE) composite, A2 shade, was placed over the cured adhesive and cured for 40 seconds. The samples were stored in distilled water at room temperature until testing. The samples were tested in shear to failure with a 1-mm/minute crosshead speed. After enamel shear bond strength testing, the teeth were again ground with 400 and 600-grit wet-dry SiC paper to obtain a flat dentin surface. The protocol used for preparing the enamel bond test samples was repeated, and the teeth were stored until testing in distilled water at room temperature. The samples were again tested in shear at a 1-mm/minute crosshead speed. Values were converted to MPa and data analyzed for intergroup differences using ANOVA and Tukey post-hoc tests. Agitation did not improve enamel SBS for any of the materials tested, but there was a significant difference in enamel SBS among materials: Clearfil SE Bond shear bond strength was greater than Xeno III, which was greater than AdheSE. At 10 seconds application time on dentin, agitation improved the Clearfil SE Bond SBS and, at 20 seconds application time on dentin, agitation significantly improved SBS to dentin for all systems tested. Agitation had no affect when the adhesive was applied to dentin for 30 seconds. Clearfil SE Bond SBS to dentin was significantly higher than the other self-etching adhesives tested except at 10 seconds without agitation.

Acrylic Resins↗