Johan Blomlöf

Effect of a chemo-mechanical caries removal system (Carisolv) on dentin topography of non-carious dentin.

The purpose of the present study was to examine the morphology of healthy dentin surfaces after treatment with Carisolv followed by conditioning with phosphoric acid and EDTA, since surface morphology may be of interest for dentin bonding. Another purpose was to evaluate the effect of treatment with Carisolv on healthy non-carious dentin surfaces with exposed collagen fibers. Scanning electron microscopy was utilized to carry out a detailed morphological examination of the dentin surfaces with regard to presence or absence of both smear layer and collagen fibers. Twelve premolars extracted for orthodontic reasons from young adults were used. The two etchants appeared to have produced two distinctly different surfaces. Etching with phosphoric acid following Carisolv treatment resulted in a porous dentin surface, while EDTA etching without prior Carisolv treatment appeared to have uncovered an intact collagen network. In contrast, the surfaces treated with Carisolv prior to EDTA etching displayed smooth intertubular surfaces with only occasional fibers. Apparently, the ability of EDTA to expose collagen in the dentin surface is counteracted or inhibited by the Carisolv treatment. Furthermore, it cannot be excluded that the Carisolv treatment in itself may have dissolved collagen fibers. Since most bonding systems claim bonding to the collagenous component of dentin, the question arises which of the etched surfaces is preferable and to what degree the collagenous component contributes to bonding strength. Further studies are thus needed to evaluate the micromechanical retention of a restoration to the different surfaces described in the present study.

Shear strength after ethylenediaminetetraacetic acid conditioning of dentin

On the basis of previous studies, it was hypothesized that a chelating agent such as ethylenediaminetetraacetic acid (EDTA) in a saturated aqueous solution (24%)can function as a dentin conditioning agent with exposure times comparable to that of phosphoric acid without compromising shear bond strength. Thirty caries-free human third molars, divided equally between two groups, were used. In group one, four experimental surfaces were prepared on each tooth, and cylindrical copper matrixes with a diameter of 5 mm were attached to the prepared surfaces. The experimental surfaces were then treated with a 24% EDTA gel for 30, 60, 120, or 240 sec, respectively. Dentin was bonded with All Bond 2, after which a flowable composite was added and light-cured. In group two, which served as control, two surfaces were prepared on each tooth. One surface was left unetched, whereas the other side was treated with 24% EDTA-gel for 30 sec. A shear bond strength test was performed at a crosshead speed of 1 mm/min until the composite debonded. There was no statistically significant difference (P < 0.89) between results of the shear bond strength test for the different EDTA conditioning times. The control group showed a significant difference in shear bond strength between untreated surfaces and surfaces conditioned for 30 sec with EDTA. Thus, the results indicate that the duration of EDTA gel conditioning of dentin surfaces need not exceed that of phosphoric acid in clinical practice to obtain an acceptable level of bond strength.