PubMed · 9002904
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M B Miller. 1995. Solving posterior composite sensitivity.. https://pubmed.ncbi.nlm.nih.gov/9002904/
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The purpose of this study was to evaluate the feasibility of aspartic acid derivative, N-acryloyl aspartic acid (N-AAsp) when used as a self-etching primer prior to the application of a commercial bonding agent containing 10-methacryloxydecyl dihydrogen phosphate. N-AAsp was synthesized by the reaction of DL-aspartic acid and acryloyl chloride. N-AAsp can be dissolved in water up to 25 wt % and can adequately remove the smear layer. When 20 wt % N-AAsp was applied as a self-etching primer, the tensile bonding strength of resin composite to dentin doubled to 16.0 MPa compared with that of the nonetching group or the 40 wt % H(3)PO(4) etching/water rinse group. Scanning electron microscopic observations revealed that the formation of the hybrid layer at the interface between the resin composite and dentin and the thickness of the hybrid layer increased with N-AAsp concentration. The hybrid layer in the specimens treated with 20 wt % N-AAsp aqueous solution presented a uniform structure, whereas those treated with 5 wt % N-AAsp solution showed a porous structure. We conclude that 20 wt % N-AAsp aqueous solution has good potential value as a self-etching primer.
Atomic force microscopy (AFM) has been used to determine microstructural changes, etching rates of peritubular dentin, and intertubular dentin recession during demineralization in dilute acidic solutions. These studies have not included many forms of altered dentin, including noncarious sclerotic root dentin associated with Cl V (abfraction) lesions. We sought to determine microstructural changes and recession rates during demineralization in citric acid (pH 2.5, 0.018M) for the transparent/sclerotic zone. Highly polished dentin disks were prepared from teeth with noncarious C1 V lesions (n = 3) and compared with normal root dentin (n = 3). Samples were etched at 5-s intervals for 1 min and at longer intervals up to 30 min. The depth changes in various portions of the dentin with respect to the reference layer were measured and changes in microstructure observed in solution in the wet cell of the AFM. In sclerotic dentin, most tubule lumens were occluded with crystalline deposits that etched more slowly than the other dentin components, but etching rates could not be determined due to their irregular geometry. The intertubular dentin recession quickly reached a plateau after a depth change of <1 microm for all dentin types, in agreement with prior work. Mixed linear regression models indicated an important difference between the etching of sclerotic intertubular dentin and that of non-sclerotic root dentin that became apparent after 600 s (p = 0.037). The sclerotic intertubular dentin underwent less depth change at the plateau (558 nm) compared to normal root dentin (744 nm). In addition, normal root dentin underwent significantly greater recession than coronal dentin (p = 0.002). The results of this study indicate that intertubular sclerotic dentin from Cl V lesions etches differently than normal root dentin, and this may help explain the difficulties in restoring such lesions with current bonding procedures.
The aim of the study was to compare the shear bond strength of a fluoride-releasing composite resin adhesive (Light Bond, Reliance) and a light-cured resin-reinforced glass ionomer cement (Fuji Ortho LC, GC America) bonded to extracted teeth under different enamel surface conditions. Forty human premolars were divided at random into 4 groups of 10 specimens. Stainless steel brackets were attached to the enamel surface by 1 of the 4 protocols: 1. Fuji Ortho LC, moist non-etched enamel; 2. Fuji Ortho LC, moist etched (37% H3PO4); 3. Light Bond, dry etched (37% H3PO4); 4. Light Bond, dry etched (Etch & Prime 3.0, Degussa). The teeth were stored in deionized water at 37 degrees C for 48 hours. Shear bond strengths was determined at a crosshead speed of 1 mm/min. The residual adhesive on the enamel surface was evaluated with the modified Adhesive Remnant Index (ARI). Analysis of variance (ANOVA) and Duncan's test were used to compare the 4 groups. Significance was predetermined at p = 0.05. Significant inter-group differences were found (p < 0.0001). The mean SBS (and SD), in MPa were: Group 1: 15.9 (4.7); Group 2: 20.3 (2.5); Group 3: 16.7 (2.6); Group 4: 11.7 (2.5). Glass ionomer cement without etching and composite with Etch & Prime showed adhesive failures at the enamel and good enamel integrity after debonding. The other specimens showed mixed or adhesive fractures at the bracket failure sites. Glass ionomer used on wet tooth surfaces without etching shows a clinically acceptable bond strength with clean separation from the enamel after debonding.