Dentinhaftung eines Retro-Zweikomponenten-Universaladhäsivs unter simulierten klinischen Bedingungen
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Abstract
Abstract
Aim of this study
The aim of this study was to investigate the dentin bonding performance of G2-Bond Universal under simulated clinical conditions. In this context, the extent to which the development of a two-component universal adhesive represents a potential step backwards compared with established adhesive systems was analysed. The influence of the adhesive strategy (etch-and-rinse versus self-etch), the use of different composite materials, including Gaenial Universal Injectable and everX Flow, as well as ageing effects following water storage, were evaluated using micro- and macro-specimens. The adhesive system Syntac® Classic was used as the control group.
Materials and methods
For the investigation, 60 extracted third molars with a standardised Class I cavity measuring 4 × 4 × 4 mm were prepared. The teeth were divided into two main groups of 30 teeth each and subsequently randomly allocated to six subgroups of five teeth each. Adhesive pretreatment of the cavities was then carried out strictly according to the manufacturers’ instructions. In eight groups, the adhesive G2-Bond Universal was applied using both the etch-and-rinse and the self-etch technique. In four additional groups, Syntac® Classic was used, serving as the control adhesive. The cavities were restored using the composite materials Gaenial Universal Injectable, everX Flow and Omniceram Bulk-Fill. The first main group was sectioned into specimens with a cross-sectional area of 1 × 1 mm immediately after restoration and subsequently stored in water. The second main group was initially stored intact in water and only thereafter sectioned into specimens of identical dimensions. Accordingly, the first main group was stored in water as micro-specimens for one month,
whereas the second main group was stored in water as macro-specimens for six months. Subsequently, a microtensile bond strength test was performed to determine the bond strength between dentin and composite [MPa]. Finally, representative fracture surfaces of the dentin were examined using scanning electron microscopy.
Results
The two main groups differed markedly in terms of their achieved bond strengths. Overall, the first main group exhibited substantially lower bond strengths than the second main group, indicating a pronounced ageing effect during storage as micro-specimens. Accordingly, the impact of water storage was considerably more pronounced in the first main group than in the second. The greatest ageing effect, expressed as the percentage reduction in bond strength, occurred in both main groups with the Etch & Rinse technique (exemplified by B / B.2 = 78.2 %). In contrast, the reduction in bond strength in the Self-Etch groups was considerably less pronounced (exemplified by A / A.2 = 46.1 %) (cf. Table 11). Irrespective of the main group, the Self-Etch technique consistently yielded higher bond strengths than the control group. Conversely, the Etch & Rinse technique resulted in lower bond strengths than the control adhesive in both main groups. The results of both main groups are presented below, starting with the second main group. In this group, G2-Bond Universal
achieved the highest bond strengths in the Self-Etch mode (A.2 = 20.01 MPa; C.2 = 17.15 MPa), substantially exceeding the bond strengths of the control group with Syntac® Classic (E.2 = 12.27 MPa). In contrast, application of the Etch & Rinse technique led to markedly reduced bond strengths (B.2 = 11.81 MPa; D.2 = 7.53 MPa), which were below those of the control group. A similar pattern was observed in the first main group. The bond strengths achieved with the Self-Etch technique (A = 10.7 MPa; C = 8.53 MPa) exceeded those of the control group (E = 4.44 MPa), whereas the Etch & Rinse technique resulted in substantially lower bond strengths (B = 2.58 MPa; D = 3.23 MPa), also below the control values. Regarding the composite materials used, higher bond strengths were achieved with Gaenial Universal Injectable than with everX Flow in both main groups. Overall, the quality of the bond strengths was primarily determined by the type of adhesive technique rather than the composite material employed. The control group F / F.2 was excluded from statistical analysis, as no stable bond could be established between Syntac® Classic and Gaenial Universal Injectable.
Conclusion
G2-Bond Universal demonstrates stable and, in some cases, superior bond strength to dentin in the Self-Etch mode compared with Syntac® Classic and other adhesive systems. The application of phosphoric acid substantially reduces dentin bond strength and is therefore only advisable in the context of controlled enamel etching, i.e., as a Selective Etch on enamel. The choice of composite material exerts a considerably smaller influence on bond strength than the adhesive strategy. HEMA-free formulation and the incorporation of an additional hydrophobic layer contribute to long-term stability. Overall, the two-bottle variant of this universal adhesive represents a clear advancement rather than a regression.
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This item has been published with the following license: In Copyright