J Korean Acad Conserv Dent.  2008 Jan;33(1):9-19. 10.5395/JKACD.2008.33.1.009.

The nanoleakage patterns of experimental hydrophobic adhesives after load cycling

• Sohn SJ
• Chang JH
• Kang SH
• Yoo HM
• Cho BH
• Son HH

• KMID: 1986745
• DOI: http://doi.org/10.5395/JKACD.2008.33.1.009

Abstract

The purpose of this study was: (1) to compare nanoleakage patterns of a conventional 3-step etch and rinse adhesive system and two experimental hydrophobic adhesive systems and (2) to investigate the change of the nanoleakage patterns after load cycling. Two kinds of hydrophobic experimental adhesives, ethanol containing adhesive (EA) and methanol containing adhesive (MA), were prepared. Thirty extracted human molars were embedded in resin blocks and occlusal thirds of the crowns were removed. The polished dentin surfaces were etched with a 35% phosphoric acid etching gel and rinsed with water. Scotchbond Multi-Purpose (MP), EA and MA were used for bonding procedure. Z-250 composite resin was built-up on the adhesive-treated surfaces. Five teeth of each dentin adhesive group were subjected to mechanical load cycling. The teeth were sectioned into 2 mm thick slabs and then stained with 50% ammoniacal silver nitrate. Ten specimens for each group were examined under scanning electron microscope in backscattering electron mode. All photographs were analyzed using image analysis software. Three regions of each specimen were used for evaluation of the silver uptake within the hybrid layer. The area of silver deposition was calculated and expressed in gray value. Data were statistically analyzed by two-way ANOVA and post-hoc testing of multiple comparisons was done with the Scheffe's test. Silver particles were observed in all the groups. However, silver particles were more sparsely distributed in the EA group and the MA group than in the MP group (p < .0001). There were no changes in nanoleakage patterns after load cycling.

Keyword

Gray value; hydrophobic adhesive; load cycling; nanoleakage

MeSH Terms

Adhesives
Chimera
Crowns
Dentin
Electrons
Ethanol
Humans
Methanol
Molar
Phosphoric Acids
Resin Cements
Silver
Silver Nitrate
Tooth
Water
Adhesives
Ethanol
Methanol
Phosphoric Acids
Resin Cements
Silver
Silver Nitrate
Water

Figure

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  Figure 1 Backscattering SEM images at low magnification (110 ×). (a) Specimens bonded with Scotchbond Multi-Purpose demonstrate relatively thick adhesive layer. (b) Specimens bonded with ethanol containing adhesive demonstrate thin adhesive layer. (c) Specimens bonded with methanol containing adhesive demonstrate thin adhesive layer. A, Adhesive; C, Composite; D, Dentin.

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  Figure 2 Backscattering SEM images (1000 ×) of specimens bonded with Scotchbond Multi-Purpose without load cycling. Silver particles were more densely deposited at the bottom of the hybrid layer even without load cycling.

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  Figure 3 Backscattering SEM images (1000 ×) of specimens bonded with Scotchbond Multi-Purpose after load cycling. Dense silver deposition was noted at the bottom of the hybrid layer and silver particles were also densely deposited around the resin tags. Note that there were little differences in nanoleakage patterns between Figure 2 and Figure 3.

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  Figure 4 Backscattering SEM images (1000 ×) of specimens bonded with ethanol containing adhesive without load cycling. Silver particles were evenly deposited within hybrid layer. Relatively low density of sliver particles were observed around the resin tags.

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  Figure 5 Backscattering SEM images (1000 ×) of specimens bonded with ethanol containing adhesive after load cycling. Note that there were no differences in nanoleakage patterns between Figure 4 and Figure 5.

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  Figure 6 Backscattering SEM images (1000 ×) of specimens bonded with methanol containing adhesive without load cycling. Loose silver deposition within the hybrid layer was observed. Sparse silver deposition was observed around the resin tags.

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  Figure 7 Backscattering SEM images (1000 ×) of specimens bonded with methanol containing adhesive after load cycling. There were no differences in nanoleakage patterns between Figure 6 and Figure 7.

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