Fractography of Metals and Plastics

Reliability and failure modes of internal conical dental implant connections

“…Macro images of failed samples were taken with a digital camera (Nikon D‐70s; Nikon, Tokyo, Japan) and utilized for failure mode classification and comparisons between groups. To identify fractographic markings and characterize failure origin and direction of crack propagation, the most representative failed samples of each group were inspected first under a polarized‐light microscope (MZ‐APO stereomicroscope; Carl Zeiss MicroImaging, Thornwood, NY, USA) and then by scanning electron microscopy (SEM) (Model S‐3500N; Hitachi, Osaka, Japan) (Parrington ; Manda et al. ).…”

Abutment Design for Implant‐Supported Indirect Composite Molar Crowns: Reliability and Fractography

“…As observed in the fractographic analysis, the marks left on the Ti surface during the fracture showed indi-cators such as beach marks, which evidence failure origin and leave traces of the successive positions of the advancing crack front. 17 Since this failure mode was not observed in crowns of group LB, it is likely that such a high load level, while leading to a cohesive failure in the latter group, resulted in cone fracture in SB-4 due to the smaller base area for stress distribution. SB-2 crowns failed at lower load levels, the reason being that their characteristic strength, as observed in the probability Weibull contour plot, was significantly lower than groups LB and SB-4.…”

“…The crown and abutment are one cementless and screwless unit, where the tapered (3 • ) interference fit abutment connects to the implant well. 16,17 Recent load-tofailure testing of molar crowns made from three indirect composites used for IACs TM has shown failures occurring at loads higher than those observed in normal occlusal function and not significantly different from metal ceramic crowns tested as controls and known as a gold standard. 18 A potential advantage in the use of composite for implant-supported restorations is that should proximal contacts be improved or the restoration's anatomy require slight alterations to favor esthetics, the adding of composite can be accomplished intraorally, in contrast to a porcelain-veneered restoration that would demand additional work by the technician and another visit by the patient.…”

An investigation of the constituent elements and modes of fracture of in vivo fractured metallic posts

“…5 Of the 60 fracture surfaces examined 40 (67%) showed evidence of ductile fracture (Fig. 7), 31 (52%) demonstrated brittle fracture (Fig.…”