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Resin tags in one bottle systems

 
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john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Mon Sep 15, 2008 11:53 am    Post subject: Resin tags in one bottle systems Reply with quote

J Adhes Dent. 2008 Feb;10(2):97-103.Links
Resin tags do not contribute to dentin adhesion in self-etching adhesives.Lohbauer U, Nikolaenko SA, Petschelt A, Frankenberger R.
Dental Clinic 1--Operative Dentistry and Periodontology, University of Erlangen-Nuremberg, Erlangen, Germany. lohbauer@dent.uni-erlangen.de

PURPOSE: Self-etching adhesives partly remove or dissolve the dentin smear layer, causing incomplete resin tag formation or low resin tag density. The quantitative contribution of properly formed resin tags to dentin adhesion was evaluated. MATERIALS AND METHODS: We assessed how the presence or absence of resin tags affects tubules of human deep-coronal dentin. G-Bond was used to bond Gradia resin composite. To ensure deep tubule penetration, we used a vacuum exsiccator. For eliminating tag formation, dentin tubules were presealed with adhesive and reverse bonded after finishing. Microtensile bond strength (muTBS) was measured on flat specimens and on Class I cavity floors. Thermocyclic loading was used to estimate the influence of resin tags on long-term behavior. Confocal laser scanning microscopy was used to evaluate adhesive interface dimensions. RESULTS: Hybrid layer thickness, tag length, and tag diameter increased under vacuum treatment. Presealing dentin tubules led to a residual tag area of 3.1% with a tag length of 10.8 microm. Under vacuum, 24.7% of the total dentin surface was covered with tags of 87.8 microm. Low C-factor preparations produced superior muTBS (71.8 to 92.7 MPa) compared with high C-factor Class I cavities (47.0 to 67.6 MPa). Thermocyclic fatigue differed from low to high C-factor situations. In Class I cavities, muTBS significantly decreased after thermocycling. On flat specimens, vacuum infiltration led to reduced muTBS after thermocyclic loading. CONCLUSION: Initially, resin tag formation did not influence the muTBS in either type of C-factor preparation. After thermocyclic loading, muTBS decreased with or without resin tags. Adhesive fracture patterns occurred at the hybrid layer/dentin interface.


ed. note:
They say "adhesives" even though they examined only one adhesive. I think it's inappropriate to extrapolate onto other systems without having examined them. John Gwinnett and I looked into this also. It's not just having tags. If the tags do not adapt to the walls of the tubules, they won't add to adhesion.

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john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Mon Sep 15, 2008 7:38 pm    Post subject: Reply with quote

Am J Dent. 1993 Feb;6(1):7-9.Links
Quantitative contribution of resin infiltration/hybridization to dentin bonding.Gwinnett AJ.
Department of Oral Biology & Pathology, SUNY at Stony Brook, Stony Brook, NY 11794.

This study determined, quantitatively, the role of resin infiltration in dentin bonding. Four groups contained 10 molar teeth. Thirty were sectioned in the mid-coronal region and the dentin ground flat with 600 grit silicon carbide paper. Group 1: smear layer intact; Group 2: smear layer removed with a Prophy Jet; Group 3: conditioned with 10% H3PO4 for 20 seconds; Group 4: comprised dentin exposed by a transverse, mid-coronal fracture. Dentin surfaces were treated with All-Bond 2, its companion bonding agent, followed by P50 resin composite, polymerized in 1 mm increments. After storage in water at 37 degrees C for 24 hours, the assemblies were tested to failure in a shear mode at a crosshead speed of 5 mm/minute. Surface and interfacial morphology was characterized using SEM. Values in MPa were: Group 1: 10.24 +/- 2.98; Group 2: 20.37 +/- 4.62; Group 3: 32.68 +/- 7.12; and Group 4: 26.77 +/- 4.85. ANOVA and student t-test showed the means statistically different (P < 0.05). Since resin penetration was only found appreciably in dentin tubules in Group 4 and tubular and intertubular penetration in Group 3, it was concluded that resin infiltration can contribute approximately one third of the shear bond strength of this total etch system.
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