Bottino Marco Antonio, Baldissara Paolo, Valandro Luiz Felipe, Galhano Graziela Avila, Scotti Roberto
Department of Dental Materials and Prosthodontics, São José dos Campos Dental School, São Paulo State University (UNESP), Brazil.
J Adhes Dent. 2007 Jun;9(3):327-31.
To evaluate the effect of cyclical mechanical loading on the bond strength of a fiber and a zirconia post bonded to root dentin.
Forty single-rooted human teeth (maxillary incisors and canines) were sectioned, and the root canals were prepared at 12 mm. Twenty randomly seleced specimens received a quartz fiber post (FRC) (D.T. Light-Post) and 20 others received a zirconia post (ZR) (Cosmopost). The posts were resin luted (All Bond 2 + resin cement Duo-link) and each specimen was embedded in epoxy resin inside a PVC cylinder. Ten specimens with FRC post and 10 specimens with ZR post were submitted to fatigue testing (2,000,000 cycles; load: 50 N; angle of 45 degrees; frequency: 8 Hz), while the other 20 specimens were not fatigued. Thus, 4 groups were formed: G1: FRC+O cycles; G2: FRC+2,000,000 cycles; G3: ZR+O cycles; G4: ZR+2,000,000 cycles. Later, the specimens were cut perpendicular to their long axis to form 2-mm-thick disk-shaped samples (4 sections/specimen), which were submitted to the push-out test (1 mm/min). The mean bond strength values (MPa) were calculated for each tooth (n = 10) and data were submitted to statistical analysis (alpha = 0.05).
Two-way ANOVA revealed that the bond strength was significantly affected by mechanical cycling (p = 0.0014) and root post (p = 0.0325). The interaction was also statistically significant (p = 0.0010). Tukey's test showed that the mechanical cycling did not affect the bonding of FRC to root dentin, while fatigue impaired the bonding of zirconium to root dentin.
(1) The bond strength of the FRC postto root dentin was not reduced after fatigue testing, whereas the bonding of the zirconia post was significantly affected by the fatigue. (2) Cyclical mechanical loading appears to damage the bond strength of the rigid post only.
评估周期性机械加载对纤维桩和氧化锆桩与牙根牙本质粘结强度的影响。
选取40颗单根人牙（上颌切牙和尖牙）进行切片，并将根管预备至12 mm。随机选取20个标本植入石英纤维桩（FRC）（D.T. Light-Post），另外20个标本植入氧化锆桩（ZR）（Cosmopost）。用树脂粘结桩（全粘结剂2 + 双固化树脂粘结剂），每个标本嵌入聚氯乙烯圆柱体内的环氧树脂中。10个植入FRC桩的标本和10个植入ZR桩的标本进行疲劳测试（2,000,000次循环；载荷：50 N；角度：45度；频率：8 Hz），另外20个标本不进行疲劳测试。由此形成4组：G1：FRC + 0次循环；G2：FRC + 2,000,000次循环；G3：ZR + 0次循环；G4：ZR + 2,000,000次循环。之后，将标本垂直于其长轴切割，形成2 mm厚的盘状样本（每个标本4个切片），并进行推出试验（1 mm/min）。计算每颗牙齿（n = 10）的平均粘结强度值（MPa），数据进行统计分析（α = 0.05）。
双向方差分析显示，粘结强度受机械循环（p = 0.0014）和桩类型（p = 0.0325）的显著影响。两者的交互作用也具有统计学意义（p = 0.0010）。Tukey检验表明，机械循环不影响FRC与牙根牙本质的粘结，而疲劳会削弱氧化锆与牙根牙本质的粘结。
（1）疲劳测试后FRC桩与牙根牙本质的粘结强度未降低，而氧化锆桩的粘结受疲劳显著影响。（2）周期性机械加载似乎仅损害刚性桩的粘结强度。
