Soares Paulo Vinicius, Santos-Filho Paulo Cesar Freitas, Martins Luis Roberto Marcondes, Soares Carlos Jose
Operative Dentistry and Dental Materials, Federal University of Uberlandia, Minas Gerais, Brazil.
J Prosthet Dent. 2008 Jan;99(1):30-7. doi: 10.1016/S0022-3913(08)60006-2.
Unresolved controversy exists concerning the preferred cavity design and restorative technique used to restore endodontically treated maxillary premolars to improve their resistance to fracture under occlusal load.
The purpose of this study was to evaluate the fracture resistance, stress distribution, and cusp deformation of endodontically treated human maxillary premolars restored with different materials. The study is divided into 2 parts. In Part I, fracture resistance and fracture mode were determined.
Seventy noncarious human maxillary premolars were selected and divided into 7 groups (n=10). The control group, ST, consisted of sound unprepared teeth. Teeth in the other 6 groups were endodontically treated and each received 1 of 2 cavity preparation designs: MODd, direct mesio-occlusal-distal preparation; MODi, indirect mesio-occlusal-distal preparation. Teeth were restored with 4 types of material: AM, MODd restored with amalgam; CR, MODd restored with composite resin; LPR, MODi restored with laboratory-processed composite resin; and LGC, MODi restored with leucite-reinforced glass ceramic. The fracture resistance (N) was assessed under compressive load in a universal testing machine. The data were analyzed by 1-way ANOVA and the Tukey HSD test (alpha =.05). Fracture modes were recorded based on the degree of tooth structure involvement and restoration damage.
Statistical analysis showed that the ST group presented the highest fracture resistance values. The restored groups showed significantly higher fracture resistance values compared to the nonrestored groups. The groups restored with adhesive techniques (LPR, CR, and LGC) presented significantly higher fracture resistance values than the group restored with the nonadhesive technique (AM) (P<.001). The catastrophic fractures were prevalent in MODd, MODi, AM, and LPR groups, and less severe fractures were found in ST and LGC groups. For the CR group, there was no prevalent fracture mode.
Teeth with the greatest amount of remaining tooth structure and those restored using adhesive technology showed higher fracture resistance values. There was great variation in the type of fracture among groups.
关于用于修复经根管治疗的上颌前磨牙以提高其在咬合负荷下抗折性的首选窝洞设计和修复技术，仍存在未解决的争议。
本研究的目的是评估用不同材料修复的经根管治疗的人上颌前磨牙的抗折性、应力分布和牙尖变形。该研究分为两部分。在第一部分中，确定抗折性和骨折模式。
选择70颗无龋的人上颌前磨牙，分为7组（n = 10）。对照组ST由未经预备的完好牙齿组成。其他6组牙齿均经过根管治疗，每组接受两种窝洞预备设计中的一种：MODd，直接近中-咬合-远中预备；MODi，间接近中-咬合-远中预备。用4种材料修复牙齿：AM，用银汞合金修复的MODd；CR，用复合树脂修复的MODd；LPR，用实验室加工的复合树脂修复的MODi；LGC，用白榴石增强玻璃陶瓷修复的MODi。在万能试验机上施加压缩载荷评估抗折性（N）。数据采用单因素方差分析和Tukey HSD检验进行分析（α = 0.05）。根据牙齿结构受累程度和修复体损坏情况记录骨折模式。
统计分析表明，ST组的抗折性值最高。修复组的抗折性值显著高于未修复组。采用粘结技术修复的组（LPR、CR和LGC）的抗折性值显著高于采用非粘结技术修复的组（AM）（P <.001）。MODd、MODi、AM和LPR组中灾难性骨折较为普遍，而ST和LGC组中骨折较轻。对于CR组，没有普遍的骨折模式。
剩余牙体组织量最大的牙齿以及采用粘结技术修复的牙齿显示出较高的抗折性值。各组之间骨折类型差异很大。
