Adhesive cementation of zirconia posts to root dentin: evaluation of the mechanical cycling effect

Abstract

This study evaluated the effect of mechanical cycling on the bond strength of zirconia posts to root dentin. Thirty single-rooted human teeth were transversally sectioned to a length of 16 mm. The canal preparation was performed with zirconia post system drills (CosmoPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 -control, no mechanical cycling; G2 -20,000 mechanical cycles; G3 -2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45° angle to the long axis of the specimens and at a frequency of 8 Hz directly on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of the teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal testing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results of the control group (7.7 ± 1.3 MPa) were statistically higher than those of G2 (3.9 ± 2.2 MPa) and G3 (3.3 ± 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strength of zirconia posts to root dentin.

Effect of Mechanical Cycling on the Push-out Bond Strength of Fiber Posts Adhesively Bonded to Human Root Dentin

“…In opposition to the current study, Galhano and others, 41 employing a similar methodology, demonstrated that the push-out bond strength between a zirconia oxide post and the root dentin was significantly reduced after the dynamic fatigue test (2x10 6 cycles). This reduction is probably related to the potential of stress concentration in the root dentin when rigid zirconia oxide posts are used, 19 which may have affected adhesion between the post and dentin.…”

Zirconia ceramic post systems: a literature review and a case report

“…On the influence of bond strength evaluation method, Table 3 shows that the bond strength of zirconia posts to natural teeth ranged between 123 N and 436 N with tensile testing 70,71,73,81) . With push-out tests, lower values in the range of 1.4−7.7 MPa were obtained instead 63,66,72) . With regard to the reduction in bond strength values when push-out testing was used, it was caused by internal stresses at the dentin-post interface 72) .…”

“…2. Retentive strength of zirconia posts The retentive strength of zirconia posts was examined using natural teeth in 11 studies 63,65,66,[70][71][72][73]77,[80][81][82] (Table 3) and in artificial post spaces using different luting agents in five studies 68,[74][75][76]79) (Table 4). The bond strength of zirconia posts to different core materials was also examined in six studies 64,67,69,78,81,83) (Table 5), thus making it a total of 21 studies .…”

Influência do método de inserção do cimento resinoso na resistência adesiva de pinos de fibra de vidro.

“…onde h = altura da área seccionada, R1 e R2 são obtidos através da medição dos diâmetros menor e maior da base, respectivamente, que correspondem, por sua vez, ao diâmetro interno entre as paredes radiculares do conduto (14,15). Estes valores foram obtidos utilizando paquímetro digital.…”