Comparative Study on Interface Fracture of 4th Generation 3-Steps Adhesive and 7th Generation Universal Adhesive

Abstract

The purpose of this paper is to compare the fracture behavior of interfaces obtained using fourth-generation and universal dental adhesives. The study relies on optic and SEM to evaluate the dentin–adhesive–restoration material interface of the samples and also on FEA simulation of fracture behavior. Specimen fabrication relied on 20 extracted teeth, in which class I cavities were created according to a protocol established based on the rules of minimally invasive therapy. For the direct adhesive technique, the adhesives used were: three-step All Bond, three-batch A and one-step Clearfil Universal Bond Quick-batch B. The restoration was performed with the same composite for both adhesives: Gradia direct posterior. The simulation used a 3D reconstructed molar on which geometric operations were performed to obtain an assembly that replicated a physical specimen. Material properties were applied to each component based on the information found in the literature. A simplified model for crack propagation was constructed, and using the fracture mechanics tool in Ansys 2019, the stress intensity factors that act at the crack tip of the adhesive interface were obtained. Mechanical simulation and microscopic investigation showed us how the interface of the dentine–adhesive–filling material performed in cases of both dental adhesives and for a certain loading condition. Important differences were identified among the adhesives, the fourth generation being superior to the fourth generation especially due to the separate steps in which the tooth surface was prepared for adhesion.

Internal Adaptation of Composite Fillings Made Using Universal Adhesives—A Micro-Computed Tomography Analysis

“…The quality of an internal tooth-filling interface can be assessed using destructive or non-destructive methods. Destructive methods use a tracer or dye and damage the sample by cutting it into sections to visualize the extent of staining along the tooth-filling interface using methods such as light microscopy, scanning electron microscopy (SEM), or optical microscopy [20,21]. Exemplary non-destructive methods are the replica technique in combination with SEM for external marginal adaptation [7,22] or X-ray micro-computed tomography (µCT) analysis [21,23].…”