Fatigue of Tooth-colored Restoratives in Aqueous Environment

Abstract

The purpose of this study was to investigate the interaction between mechanical and chemical fatigue in resin composites and dental ceramics, and the effects thereof on fatigue resistance of tooth-colored restoratives. To this end, the fatigue fracture resistance of restoratives under dry and aqueous conditions were analyzed by a dynamic fatigue crack propagation test using beam-shaped specimens with a precrack. Fatigue crack propagation characteristics were expressed by the correlation between fatigue crack growth rate (da/dN) and stress intensity factor range (ΔK). In addition, fatigue crack growth threshold (ΔKth) was calculated. Following the fatigue test, a fractographic examination was performed using scanning electron microscopy. Fatigue crack initiation was retarded in resin composites under aqueous condition, but dental ceramics were susceptible to slow crack growth after crack initiation. SEM images of the fatigue facture surfaces reflected inorganic and organic filler particles of different sizes in composites and the bonding at crystal-glass interface in ceramics. It was concluded that water exerted different effects on the fatigue resistance of composites and ceramics.

Surface properties of dental polymers: measurements of contact angles, roughness and fluoride release

“…Aesthetic restorative materials of composite resins regularly used in dentistry are composed of polymers to which inorganic particles are usually associated [1][2][3][4][5] . These polymers, mainly BIS-GMA 6 , exhibit several particular characteristics such as the release of residual monomers, microporosity and cracking, etc [7][8][9] .…”

Temporary Stability of Compressive Strength of Flow and Universal Type LC PMCCS Materials

“…The structure of the composite can have an impact on the development of such cracks. As it has been demonstrated by Kawakami et al [26], propagation of cracks in composites containing pre-polymerized particles occurs at a lower range of WIN boundary values ∆Kth than in the case of materials containing large particles. The absorption inside LC PMCCs takes place mainly through the matrix and the socalled interphase.…”

Mechanical properties and DIC analyses of CAD/CAM materials

“…Similar findings have been reported by other authors when glass ceramics was compared with hybrid composite resin blocks (11). Furthermore, the wearing process that occurs during mastication is also important, and material fatigue will start as soon as the first cracks begin to show up on the occlusal surface (2). On composite resin materials a softening effect is induced by hydrolysis and will accelerate the in vivo wear of the composite resin block (21).…”

“…With a span (S0) of 12mm the three-pointing bend test was performed in a Universal testing machine (Test Resources, Shakopee, MN, USA) at a crosshead speed of 0.5mm/min until failure. The fracture toughness (Kic) of each material was calculated following equations (1) and (2): (Figs. 2,3).…”

“…Resin composite CAD/CAM blocks seem to have on advantage over ceramic CAD/CAM blocks in terms of resilience and less abrasion on the antagonist enamel, helping to preserve overall balance of the dentition, and can also be easily adjusted or repaired (13). In contrast, all ceramic restorations have a high clinical failure rate in posterior sites (14,15), and are frequently replaced because of bulk fracture (2,16). Crack propagation of ceramic materials during mechanical deformation normally occurs differently from plastic materials (17).…”