The Effect of the Application Sequence of Casein Phosphopeptide-Amorphous Calcium Phosphate Paste on the Shear Bond Strength of Etch-and-Rinse Resin Cements to Dentin

PURPOSE

To evaluate the effect of the application sequence of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI paste) on shear bond strength (SBS) of 2 etch-and-rinse resin cements to dentin.

MATERIALS AND METHODS

Sixty extracted human maxillary premolars were cut to expose the mid-coronal dentin surfaces. The teeth were randomly divided into 6 groups (n = 10), based on the resin cement used and CPP-ACP application. In groups 1-3, Excite DSC/Variolink II and in groups 2-4, One-Step Plus/Duolink was bonded to dentin. There were 3 groups for each cement as follows: with no treatment as a control; 3-minute application of CPP-ACP before acid etching (CPP-ACP/Etching); 3-minute application of CPP-ACP after acid etching (Etching/CPP-ACP). After storage in distilled water at 37°C for 24 hours, SBS test was performed. Data were analyzed with 2-way ANOVA and post-hoc Tukey test (α = 0.05).

RESULTS

CPP-ACP application on the dentin before and after acid etching significantly decreased the SBS of OS/Duolink (13.60 and 14.71 MPa, respectively vs. control; 21.21 MPa, p < 0.001); however, it did not influence the SBS of Excite DSC/Variolink II (25.14 MPa) before acid etching (27.37 MPa) or after acid etching (26.41 MPa, p > 0.388). The application sequence of CPP-ACP did not influence the SBS of etch-and-rinse resin cements evaluated.

CONCLUSION

CPP-ACP applications may lower the SBS in some etch-and-rinse resin cements, and timing of applications makes no difference.

Effect of desensitizing agents on the microtensile bond strength of two-step etch-and-rinse adhesives to dentin

Desensitizers can be used to control postoperative sensitivity in adhesive restorations. The aim of this study was to evaluate the effect of desensitizing agents on the bond strength of two-step etch-and-rinse adhesive systems to dentin. Forty-two human molars were sectioned to obtain 3-mm-thick dentin discs. The discs were divided into three groups (n = 14 in each) - no-treatment control group (CT), and oxalic acid [BisBlock (BB)] and calcium phosphate [Desensibilize Nano-P (NP)] desensitizers - before the application of two adhesive systems [Adper Single Bond Plus (SB) and One-Step Plus (OSP)]. A nanoparticle composite resin was used to create a 3-mm-thick build-up. The specimens were stored in distilled water for 24 h before a microtensile bond-strength test was performed. The failure modes were determined using a stereomicroscope at 100 × magnification. Specimens were sectioned perpendicular to the interface for scanning electron microscopy analyses. The CT-SB group exhibited the highest bond strength, differing significantly from BB-SB and BB-OSP groups. Mixed failures were prevalent for all groups. Scanning electron microscopy revealed a continuous hybrid layer and resin tags in all groups. Dentin bond strength of etch-and-rinse adhesive systems was reduced by an oxalic acid desensitizer but was not affected by a calcium phosphate-containing desensitizer.

An in vitro evaluation of the effects of desensitizing agents on microleakage of Class V cavities

Background

The aim of this study was to evaluate the effect of a desensitizing agent on microleakage of Class V cavities.

Material and Methods

72 premolar teeth were used. There were 6 groups. Class V restorations were prepared with two different restorative materials (Equia fil, GC, America and Grandio, VOCO, Germany) and two adhesive systems (Clearfil SE Bond, Kuraray, Japan and S3 Bond Plus, Kuraray, Japan) with and without desensitizing agent (Gluma Desensitizer, Heraeus Kulzer, Germany). Restorations were polished with aluminum oxide abrasive discs. Then a range of 5 - 55C thermocycling was performed 10.000 times. The microleakage of restorations was examined with dye penetration method (Basic fuchsine). Bonferroni corrections and Kruskal-Wallis test were used to determine the significance of differences in occlusal and gingival dye penetration scores between groups.

Results

There was no stastistical significance between the occlusal and gingival microleakage scores within the groups were shown.

Conclusions

It can be concluded that use of desensitizing agent under both high viscosity glass ionomer restorative materials and resin composites doesn’t affect the microleakage.

Key words:High viscosity glass ionomer cement, composite resin, desensitizing agent, microleakage.

Effect of surface pretreatment with two desensitizer techniques on the microleakage of resin composite restorations

This study evaluated the effect of two desensitizing procedures on the marginal microleakage of composite restorations bonded by a two-step etch-and-rinse adhesive. Class V cavities were prepared on the buccal surfaces of 42 extracted premolars at the cementoenamel junction and randomly divided into three groups of 14 each. In group 1 (control), an adhesive (Excite) was applied according to manufacturer's instructions. In group 2, after the application of oxalate desensitizer (BisBlock) to the cavities, the specimens were etched, and Excite was applied and light cured. In group 3, the cavities were treated with CO(2) laser irradiation (1 W power output in a continuous wave mode, 10 s), and then, the specimens were etched and bonded by Excite. All the cavities were restored with a resin composite. After water storage and thermocycling, the specimens were placed in 1 % basic fuchsin blue dye solution. The dye penetration was evaluated using a stereomicroscope. The data were analyzed by using Kruskal-Wallis and Mann-Whitney statistical tests (α = 0.05). There was a significant difference among three groups at the gingival and occlusal margins (P < 0.05). The specimens treated with BisBlock exhibited higher microleakage at both margins than those of the control and laser-treated groups (P < 0.001). There was no significant difference between the control group and group treated with CO(2) laser at both margins (P > 0.05). CO(2) laser did not show a detrimental effect on the marginal sealing ability of the adhesive system used in resin composite restorations. However, oxalate desensitizer adversely influenced the sealing ability of the restorations.

Effect of oxalate desensitizer on the bonding durability of adhesive resin cements to dentin

PURPOSE

This study investigated whether the tubular occluding effect of oxalate desensitizer (OX) during adhesive cementation improved bonding of a self-etch and two etch-and-rinse resin cements to dentin after 6 months.

METHODS

A flat dentin surface was prepared on 120 extracted premolars, which were randomly divided into six groups of 20 teeth each according to the adhesive resin cement system used: ED primer II/Panavia F2.0, Excite DSC (Ex DSC)/Variolink II, and One-Step Plus (OS Plus)/Duolink, with or without OX (BisBlock) application. After cementation of an indirect composite rod, two subgroups (n=10) were tested after 24 h and 6 months of water storage plus thermocycling, and shear bond strengths were recorded in MPa.

RESULTS

Statistical tests showed that although oxalate had a borderline significant negative effect on initial bonding of ED primer II/Panavia F2.0, it significantly improved bonding durability (p<0.05). OX severely compromised the initial bond strength of Ex DSC/Variolink II (p<0.001) but had no effect on the reduction in bonding after aging. OX was compatible with OS Plus/Duolink and did not affect the loss of bonding strength after 6 months (p>0.05).

CONCLUSION

Combining an oxalate desensitizer with three types of resin cements had different effects on bond strength to dentin after aging, depending on the interaction of oxalate with the adhesive system associated to the resin cement.