Soares Carlos Jose, Martins Luis Roberto Marcondes, Fonseca Rodrigo Borges, Correr-Sobrinho Lourenco, Fernandes Neto Alfredo Julio
School of Dentistry, Federal University of Uberlandia, Minas Gerais, Brazil.
J Prosthet Dent. 2006 Jun;95(6):421-9. doi: 10.1016/j.prosdent.2006.03.022.
Controversy exists concerning the preferred cavity design for posterior ceramic restorations to improve their resistance to fracture under occlusal load.
The aim of this study was to assess the resistance to fracture of leucite-reinforced ceramic restorations placed on molars with different cavity preparation designs.
Ninety noncarious molars were selected, stored in 0.2% thymol solution, and divided into 9 groups (n = 10): IT, intact teeth; CsI, conservative inlay; ExI, extensive inlay; CsO/mb, conservative onlay with mesio-buccal cusp coverage; ExO/mb, entensive onlay with mesio-buccal cusp coverage; CsO/b, conservative onlay with buccal cusp coverage; ExO/b, entensive onlay with buccal cusp coverage; CsO/t, conservative onlay with total cusp coverage; ExO/t, extensive onlay with total cusp coverage. Teeth were restored with a Leucite-reinforced ceramic (Cergogold). The fracture resistance (N) was assessed under compressive load in a universal testing machine. The data were analyzed with 1-way and 2-way analyses of variance, followed by the Tukey HSD test (alpha = .05). Fracture modes were recorded, based on the degree of tooth structure and restoration damage.
One-way analysis showed that intact teeth had the highest fracture resistance values. Two-way analyses showed no significant differences for the isthmus extention factor, but showed a significant difference for the preparation design type of fracture (P = .03), and also for the interaction between both factors (P = .013). The fracture mode observed in all groups tended to involve only restorations.
Within the limitations of this study, it was observed that cuspal coverage does not increase fracture resistance of the posterior tooth-restoration complex restored with leucite-reinforced ceramics.
关于后牙陶瓷修复体的理想洞型设计，以提高其在咬合负荷下的抗折性，目前存在争议。
本研究的目的是评估采用不同洞型预备设计的磨牙上放置的白榴石增强陶瓷修复体的抗折性。
选取90颗无龋磨牙，保存在0.2%麝香草酚溶液中，并分为9组（n = 10）：IT，完整牙齿；CsI，保守嵌体；ExI，广泛嵌体；CsO/mb，覆盖近中颊尖的保守高嵌体；ExO/mb，覆盖近中颊尖的广泛高嵌体；CsO/b，覆盖颊尖的保守高嵌体；ExO/b，覆盖颊尖的广泛高嵌体；CsO/t，覆盖所有牙尖的保守高嵌体；ExO/t，覆盖所有牙尖的广泛高嵌体。用白榴石增强陶瓷（Cergogold）修复牙齿。在万能试验机上施加压缩负荷评估抗折性（N）。数据采用单向和双向方差分析，随后进行Tukey HSD检验（α = 0.05）。根据牙齿结构和修复体损伤程度记录折裂模式。
单向分析显示完整牙齿的抗折性值最高。双向分析显示峡部扩展因素无显著差异，但在折裂的预备设计类型上有显著差异（P = 0.03），并且在两个因素之间的相互作用上也有显著差异（P = 0.013）。所有组中观察到的折裂模式往往仅涉及修复体。
在本研究的局限性内，观察到覆盖牙尖并不能增加用白榴石增强陶瓷修复的后牙修复复合体的抗折性。
