水泥类型对单层氧化锆全瓷冠和双层氧化锆全瓷冠抗折强度和破坏模式的影响。

Department of Oral Rehabilitation Sciences, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon.

Department of Fixed Prosthodontics, Faculty of Dentistry, Sinai University, Kantara Campus, Sinai, Egypt, Phone: +20 1288670943, e-mail:

J Contemp Dent Pract. 2023 Aug 1;24(8):576-581. doi: 10.5005/jp-journals-10024-3546.

AIM

To compare the fracture resistance and the mode of failure between monolith second-generation zirconia and bilayered first-generation zirconia single crowns cemented by resin cement and glass ionomer cement (GIC).

MATERIALS AND METHODS

A total of 36 maxillary first premolar crowns (5 mm in length × 4 mm in cervical diameter, with a base of 6 mm) were computer-aided design-computer-aided manufacturing (CAD-CAM) milled. They were divided into the following two groups ( = 18) according to the fabrication techniques: Group M - monolith zirconia crown (1-mm axial thickness and 2-mm occlusal thickness) and group B - bilayer zirconia crown (0.5-mm axial thickness and 1-mm occlusal thickness). Each group was further subdivided into the following two subgroups ( = 9) according to the cement used: Subgroup G - cemented using GIC; subgroup R - cemented using resin cement. All crowns were cemented to their corresponding resin dies and stored in distilled water for 72 hours. Each specimen was mounted to the lower member of the universal testing machine with a load cell of 5 kN and a crosshead speed of 0.5 mm/minute. Failure modes were analyzed for fractured parts using scanning electron microscopy (SEM).

RESULTS

Subgroup MR recorded the highest fracture resistance mean value (3616 ± 347.2 N) while the BG subgroup recorded the statistically significant lowest fracture resistance mean value (1728.7 ± 115.3 N). One-way analysis of variance (ANOVA) followed by pairwise Tukey's tests revealed a statistically significant difference ( = 0.0001) between groups M and B. One-way ANOVA followed by pairwise Tukey's tests also showed a statistically significant difference ( = 0.0297) between the types of cement used (subgroups G and R).

CONCLUSION

Monolith zirconia crowns had better mean fracture resistance than bilayered zirconia crowns. Resin cement improved the fracture resistance compared to GIC. Monolith zirconia crowns showed bulk fracture while bilayered zirconia crowns showed chipping fracture.

CLINICAL SIGNIFICANCE

Monolith zirconia crowns present a good prosthetic alternative overcoming the veneer chipping drawback of bilayered zirconia crowns. In addition, resin cement could increase the fracture resistance of zirconia crowns.

目的

比较第二代整体氧化锆和第一代双层氧化锆单冠在树脂水门汀和玻璃离子水门汀（GIC）粘结下的抗折强度和失效模式。

材料与方法

共制作 36 个上颌第一前磨牙冠（长 5mm，颈径 4mm，基底 6mm），采用计算机辅助设计-计算机辅助制造（CAD-CAM）铣床制作。根据制作技术将其分为以下两组（n=18）：组 M-整体氧化锆冠（1mm 轴厚和 2mm 牙合面厚）和组 B-双层氧化锆冠（0.5mm 轴厚和 1mm 牙合面厚）。每组根据粘结剂进一步分为以下两个亚组（n=9）：亚组 G-使用 GIC 粘结；亚组 R-使用树脂水门汀粘结。所有牙冠均粘结到相应的树脂模型上，并在蒸馏水中储存 72 小时。每个标本均用 5kN 的负载单元和 0.5mm/min 的十字头速度安装在下位机上。使用扫描电子显微镜（SEM）分析断裂部分的失效模式。

结果

亚组 MR 记录的抗折强度平均值最高（3616±347.2N），而亚组 BG 记录的抗折强度平均值最低（1728.7±115.3N）。单因素方差分析（ANOVA）后进行两两 Tukey 检验显示组 M 和 B 之间存在统计学显著差异（P=0.0001）。单因素方差分析后两两 Tukey 检验还显示，粘结剂类型（亚组 G 和 R）之间存在统计学显著差异（P=0.0297）。