Visualization of Marginal Integrity of Resin-Enamel Interface by Holographic Interferometry

Abstract

Operative Dentistry, 2007, 32-3, 266-272 Clinical RelevanceHolographic interferometry offers precise insight into both the frequency and location of cohesive fractures through its fringe information. If flowable composites are not used as a first layer, fringe distribution indicates cohesive fractures as a consequence of composite polymerization. SUMMARYThis study determined whether it was possible to detect deformations and fractures in dental hard tissues or in composite material from internal stresses using double-exposure holographic interferometry. On the proximal side of eight intact human permanent premolars, a direct Class II cavity was prepared and restored with a self-etching adhesive (Clearfil SE Bond) and Tetric Ceram, a resin composite. In five of the specimens, Tetric Flow was used as an elastic layer. The samples were illuminated using a helium-neon laser beam, and the holograms of samples were recorded using Agfa 10E75 photographic plates. Hologram reconstructions were captured with an 8-bit monochrome CCD camera and qualitatively analyzed. Deformations and fractures appeared as fringe patterns on all interferograms, where the distribution of fringes provided location information, while the density of fringes gave the amplitude information. Greater fringe densities were observed in samples treated without a flowable composite.

Evaluation of polymerization shrinkage of bulk-fill resin composites using microcomputed tomography

“…Polymerisation shrinkage causes several complications, such as a disjunction at the tooth-composite interface [3], enamel cracks [4] and secondary caries. When using conventional resin composites, an incremental layering technique is advised to control the shrinkage, but this technique is time-consuming.…”

Monomer conversion and shrinkage force kinetics of low-viscosity bulk-fill resin composites

“…However, polymerization shrinkage is highly correlated to polymerization stress, which is known as a contributing factor for restoration failure [9]. This polymerization-induced stress, being the result of confining the shrinking material by bonding to cavity walls, is considered responsible for a series of clinical complications including tooth-composite interfacial debonding [10], enamel cracking [11], cuspal deflection [12], post-operative sensitivity [13], and secondary caries [14]. Besides volumetric shrinkage and imposed cavity restrictions, the visco-elastic behavior of the material, usually described in terms of elastic modulus development and flow capacity, is an important determinant in the development of polymerization stress [15].…”

A micro-computed tomography evaluation of the change in volume of different bulk-fill composite materials caused by polymerization shrinkage

“…By creating tension between the tooth and the material, polymerization shrinkage weakens the integrity of the restoration (4). As a result of volumetric changes occurring during polymerization, there may be a separation in the tooth-composite interface, causing secondary caries and cracks in the enamel (8,9). For successful composite restorations, the composite-tooth merging is of great importance in protecting the marginal integrity.…”