Gomes Rafael Soares, Souza Caroline Mathias Carvalho de, Bergamo Edmara Tatiely Pedroso, Bordin Dimorvan, Del Bel Cury Altair Antoninha
Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba, Departamento de Prótese e Periodontia, Piracicaba, SP, Brasil.
Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba, Departamento de Odontologia Restauradora, Piracicaba, SP, Brasil.
J Appl Oral Sci. 2017 May-Jun;25(3):282-289. doi: 10.1590/1678-7757-2016-0233.
In this study, marginal and internal misfit and fracture load with and without thermal-mechanical aging (TMA) of monolithic ZLS and lithium disilicate (LDS) crowns were evaluated.
Crowns were milled using a computer-aided design/computer-aided manufacturing system. Marginal gaps (MGs), absolute marginal discrepancy (AMD), axial gaps, and occlusal gaps were measured by X-ray microtomography (n=8). For fracture load testing, crowns were cemented in a universal abutment, and divided into four groups: ZLS without TMA, ZLS with TMA, LDS without TMA, and LDS with TMA (n=10). TMA groups were subjected to 10,000 thermal cycles (5-55°C) and 1,000,000 mechanical cycles (200 N, 3.8 Hz). All groups were subjected to compressive strength testing in a universal testing machine at a crosshead speed of 1 mm/min until failure. Student's t-test was used to examine misfit, two-way analysis of variance was used to analyze fracture load, and Pearson's correlation coefficients for misfit and fracture load were calculated (α=0.05). The materials were analyzed according to Weibull distribution, with 95% confidence intervals.
Average MG (p<0.001) and AMD (p=0.003) values were greater in ZLS than in LDS crowns. TMA did not affect the fracture load of either material. However, fracture loads of ZLS crowns were lower than those of LDS crowns (p<0.001). Fracture load was moderately correlated with MG (r=-0.553) and AMD (r=-0.497). ZLS with TMA was least reliable, according to Weibull probability.
Within the limitations of this study, ZLS crowns had lower fracture load values and greater marginal misfit than did LDS crowns, although these values were within acceptable limits.
在本研究中，评估了整体式零收缩锂硅（ZLS）和二硅酸锂（LDS）全冠在有和没有热机械老化（TMA）情况下的边缘和内部适合性以及断裂载荷。
使用计算机辅助设计/计算机辅助制造系统铣削全冠。通过X射线显微断层扫描测量边缘间隙（MGs）、绝对边缘差异（AMD）、轴向间隙和咬合间隙（n = 8）。对于断裂载荷测试，将全冠粘结在通用基台上，并分为四组：未进行TMA的ZLS、进行TMA的ZLS、未进行TMA的LDS和进行TMA的LDS（n = 10）。TMA组经历10000次热循环（5 - 55°C）和1000000次机械循环（200 N，3.8 Hz）。所有组在万能试验机中以1 mm/min的十字头速度进行抗压强度测试，直至破坏。采用学生t检验来检查适合性，双向方差分析用于分析断裂载荷，并计算适合性与断裂载荷的皮尔逊相关系数（α = 0.05）。根据威布尔分布对材料进行分析，并给出95%置信区间。
ZLS全冠的平均MG值（p < 0.001）和AMD值（p = 0.003）大于LDS全冠。TMA对两种材料的断裂载荷均无影响。然而，ZLS全冠的断裂载荷低于LDS全冠（p < 0.001）。断裂载荷与MG（r = -0.553）和AMD（r = -0.497）呈中度相关。根据威布尔概率，进行TMA的ZLS可靠性最低。
在本研究的局限性范围内，ZLS全冠的断裂载荷值低于LDS全冠，边缘适合性也更差，尽管这些值在可接受范围内。
