Shear bond strengths of seven self-etching primers after thermo-cycling

Influence of the Application Time of Silane for the Bonding Performance between Feldspar or Lithium Disilicate Ceramics and Luting Resin Composites

A correct silanization time is essential for successful surface functionalization and sufficient bonding to dental ceramics. The shear bond strength (SBS) of lithium disilicate (LDS) and feldspar (FSC) ceramics and luting resin composite was investigated with respect to different silanization times, taking into account the physical properties of the individual surfaces. The SBS test was performed with a universal testing machine, and the fracture surfaces were evaluated by stereomicroscopy. The surface roughness of the prepared specimens was analyzed after etching. Changes in surface properties due to surface functionalization were evaluated by surface free energy (SFE) via contact angle measurement. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical binding. The roughness and SBS of the control group (no silane, etched) were higher for FSC than for LDS. Regarding the SFE, the dispersive fraction increased and the polar fraction decreased after silanization. FTIR confirmed the presence of silane on the surfaces. The SBS of LDS showed a significant increase from 5 to 15 s, depending on the silane and luting resin composite. For FSC, cohesive failure was observed for all samples. For LDS specimens, a silane application time of 15 to 60 s is recommended. Based on clinical conditions, no difference between the silanization times was observed for FSC specimens, indicating that etching alone produces sufficient bonding.

Siloranes-Suitability of a Novel Adhesive for Orthodontic Bracket Bonding

Recently, an epoxy-based resin-Filtek Silorane-has been proposed for restorative fillings. It was the aim of the investigation to evaluate the suitability of this novel resin for orthodontic bracket bonding on unground enamel. Shear bond strength was measured for two adhesives-Filtek Silorane, Transbond XT-in combination with steel, ceramic and polymer brackets. For Filtek Silorane etching was performed with the Silorane self-etching primer, as well as phosphoric acid. The Transbond XT samples were etched with phosphoric acid only and served as the control group. All samples were thermo-cycled (1000×, 5-55 °C). Shear testing was carried out with an Instron 3344. In addition, ARI scores were evaluated. The Shear bond strength showed a weak adhesion of Filtek Silorane to unprepared enamel, either with the self-etching primer or the conventional etching (0.87-4.28 MPa). The Shear bond strength of the control group was significantly higher (7.6-16.5 MPa). The ARI scores showed a clear failure at the enamel-adhesive interface for all Filtek Silorane samples. For the combination of Transbond XT and different brackets the failure was found at the adhesive-bracket interface. The novel epoxy-based resin Filtek Silorane is not appropriate for bracket bonding to unprepared enamel.

Effect of Adhesion Boosters on the Indirect Bonding with the Lingual Brackets: An In Vitro Study

Aims and Objectives:

To evaluate the influence of the two adhesion boosters (assure universal bonding resin and enhance adhesion booster) on the shear bond strengths of indirectly bonded lingual brackets.

Materials and Methods:

A total of 120 extracted human teeth were randomly divided into 3 groups (n = 40), each group contained equal number of anterior and posterior teeth (anterior = 20, posterior = 20), and their lingual surfaces were etched by using 37% phosphoric acid. The bracket was bonded indirectly without using adhesion booster in group 1 (control group). In group 2, the adhesion booster A (enhance adhesion booster) and adhesion booster B (assure universal bonding resin) in group 3 were applied, respectively, before the bonding. The universal testing machine was used to measure the maximum bond strength. Student’s t-test followed by the one-way analysis of variance was used to compare shear bond strength among the groups.

Results:

The shear bond strength was found to be highest in group 3, followed by group 2, and it was least in controls. There were highly significant differences statistically in shear bond strength among the groups 1, 2, and 3 ( P = .001).

Conclusion:

Shear bond strength was admissible in all the groups. The application of the assure universal bonding resin significantly increased the bond strength of lingual brackets in indirect bonding.

Enamel shear bond strength of different primers combined with an orthodontic adhesive paste

AIM

The aim of this study was a comparison of shear bond strength (SBS) on tooth enamel of different primers combined with the adhesive paste Transbond XT.

MATERIALS AND METHODS

Forty bovine teeth were used in order to create 40 test blocks. The blocks were divided into four groups of 10 blocks each: group A - sample primer (SP); group B - Opal Seal (OS); group C - Transbond Plus SEP (TSEP); group D - Transbond XT Primer (TXT). After surface preparation and application of the primer, respectively, two stainless steel brackets were fixed on each tooth by using Transbond XT. Accordingly, 80 brackets were debonded (n=20). Shear bond strength and adhesive remnant index (ARI) scores were evaluated. Statistical analyses were performed by using the Student's t-test and Mann-Whitney U test.

RESULTS

All tested groups revealed high shear bond strength in a similar size range. There were no significant differences between the groups concerning shear bond strength. The ARI scores of group C showed significantly lower ARI scores (0 and 1) than that of group D. Apart from that there was no statistical difference.

CONCLUSION

In combination with the adhesive paste Transbond XT, all tested primers were suitable for fixing orthodontic brackets. The primers could be changed according to the clinical situation.

Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison

Purpose. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. Materials and Methods. 12 vinylpolysiloxane, 2 polyether, and 3 hybrid vinylpolyether silicone-based impression materials were tested. For each material, 10 dumbbell-shaped specimens were fabricated (n = 10), according to the ISO 37:2005 specifications, and loaded in tension until failure. Mean values for tensile strength, yield strength, strain at break, and strain at yield point were calculated. Data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). Results. Vinylpolysiloxanes consistently showed higher tensile strength values than polyethers. Heavy-body materials showed higher tensile strength than the light bodies from the same manufacturer. Among the light bodies, the highest yield strength was achieved by the hybrid vinylpolyether silicone (2.70 MPa). Polyethers showed the lowest tensile (1.44 MPa) and yield (0.94 MPa) strengths, regardless of the viscosity. Conclusion. The choice of an impression material should be based on the specific physical behavior of the elastomer. The light-body vinylpolyether silicone showed high tensile strength, yield strength, and adequate strain at yield/brake; those features might help to reduce tearing phenomena in the thin interproximal and crevicular areas.

Effects of sandblasting before orthophosphoric acid etching on lingual enamel: in-vitro roughness assessment

INTRODUCTION

In this study, we evaluated changes in lingual enamel roughness due to sandblasting with 27-, 50-, and 90-μm aluminum oxide particles followed by 37% orthophosphoric acid etching.

METHODS

Twenty-four maxillary premolars were included in the study. The lingual enamel roughness of 20 teeth was evaluated using a laser confocal microscope before and after enamel conditioning. Group 1 (control) was etched with 37% orthophosphoric acid; groups 2, 3, and 4 were sandblasted with 27-, 50-, and 90-μm aluminum oxide particles, respectively, before acid etching. The lingual surfaces of the other 4 teeth were evaluated using scanning electron microscopy after they had received one of the conditioning methods under study. Paired t tests were used to compare the roughness parameters obtained before and after conditioning in each group, and 1-way analysis of variance was used to compare the surface roughness between groups. The significance level was set at 5% for all statistical analyses.

RESULTS

The 4 conditioning methods significantly increased the roughness of the lingual enamel. However, the roughness increases in the groups that were sandblasted with 27-, 50-, and 90-μm aluminum oxide particles before orthophosphoric acid etching were statistically greater than was the increase in the group conditioned only with orthophosphoric acid. Scanning electron microscopy showed different conditioning patterns among specimens that were conditioned only with orthophosphoric acid and those sandblasted with aluminum oxide before acid etching.

CONCLUSIONS

Lingual enamel conditioning with aluminum oxide sandblasting before acid etching results in greater roughness and produces a conditioning pattern different from that of acid etching alone.

Influence of different methods of cleaning custom bases on the shear bond strength of indirectly bonded brackets

OBJECTIVE

To determine the influence on shear bond strength and bond failure location of four cleaning methods for orthodontic bracket custom bases.

DESIGN

In vitro laboratory study.

MATERIAL AND METHODS

Eighty bovine teeth were divided at random into four groups. The bracket custom bases were cleaned with different methods: group 1 with methyl methacrylate monomer, group 2 with acetone, group 3 with 50 μm aluminium oxide particles and group 4 with detergent. The brackets were indirectly bonded onto the teeth with the Sondhi Rapid-Set self-curing adhesive. The maximum required shear bond strength to debond the brackets was recorded. The bond failure location was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance (ANOVA) analysis (P<0·05) was used to detect significant differences in the bond strength. Kaplan-Meier survival plots and log-rank test were done to compare the survival distribution between the groups. The Kruskal-Wallis test (P<0·05) was used to evaluate the differences in the ARI scores.

RESULTS

The mean bond strengths in groups 1, 2, 3 and 4 were 23·7±5·0, 25·3±5·1, 25·6±3·7 and 25·7±4·2 MPa, respectively. There were no significant statistically differences in either the bond strength or the ARI score between the groups.

CONCLUSION

The four custom base-cleaning methods presented the same efficiencies on indirect bond of the brackets; thus, practitioners can choose the method that works best for them.

Effect of adhesion boosters on indirect bracket bonding

OBJECTIVE

To determine the influence of two adhesion boosters on shear bond strength and on the bond failure location of indirectly bonded brackets.

MATERIALS AND METHODS

Sixty bovine incisors were randomly divided into three groups (n = 20), and their buccal faces were etched using 37% phosphoric acid. In group 1 (control), brackets were indirectly bonded using only Sondhi adhesive. In groups 2 and 3, the adhesion boosters Enhance Adhesion Booster and Assure Universal Bonding Resin, respectively, were applied before bonding with Sondhi. Maximum bond strength was measured with a universal testing machine, and the location of bond failure was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance followed by the Tukey test (P < .05) was used to compare the shear bond strength among groups, and the differences in ARI scores were evaluated using the Kruskal-Wallis test (P < .05). The Pearson correlation coefficient was calculated to determine whether there was any correlation between bond strength and ARI scores.

RESULTS

The mean shear bond strength in group 3 was significantly higher (P < .01) than in the other groups. Evaluation of the locations of bond failure revealed differences (P < .05) among the three groups. There was a moderate correlation between bond strength and ARI scores within group 3 (r  =  0.5860, P < .01).

CONCLUSION

In vitro shear bond strength was acceptable in all groups. The use of the Assure adhesion booster significantly increased both the shear bond strength of indirectly bonded brackets and the amount of adhesive that remained on the enamel after bracket debonding.