Wu Younong, Cathro Peter, Marino Victor
Dental Research Institute, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
J Biomed Res. 2010 Nov;24(6):474-8. doi: 10.1016/S1674-8301(10)60063-2.
We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture. Eighteen upper premolars were divided equally into 3 groups. Group 1 consisted of intact controls; group 2 had access cavities and root canal preparations; group 3 as in group 2 but obturated with gutta-percha and AH26, and the access cavity restored with glass ionomer and composite. Specimens were submitted to compressive strength testing using the Hounsfield Universal H50KM testing machine with a load cell of 2000 Newtons and a crosshead speed set at 1.0 mm/min until fracture. The results from the compressive strength tests showed that intact controls (1105.83±90.93 MPa) and restored premolars (936.67±44.67 MPa) were significantly different from premolars with unrestored access cavities 568.33±105.49 MPa. There was no significant difference between intact controls and restored premolars. The predominant fracture pattern for intact teeth was an oblique fracture. For premolars that had endodontic access cavities, restored or unrestored, the most common fracture pattern was a vertical fracture. The restoration of occlusal access cavities with glass ionomer and composite provided fracture resistance close to that of intact controls, but when restored teeth fractured, they were predominantly non-restorable.
我们研究了对上颌前磨牙进行根管充填和修复牙髓合面进入洞是否能提供可接受的抗折性和折裂模式。18颗上颌前磨牙被平均分为3组。第1组为完整对照；第2组有进入洞和根管预备；第3组与第2组相同，但用牙胶和AH26进行根管充填，并用玻璃离子体和复合树脂修复进入洞。使用荷载传感器为2000牛顿、十字头速度设定为1.0毫米/分钟的Hounsfield通用H50KM试验机对标本进行抗压强度测试，直至其折断。抗压强度测试结果表明，完整对照（1105.83±90.93兆帕）和修复后的前磨牙（936.67±44.67兆帕）与未修复进入洞的前磨牙（568.33±105.49兆帕）有显著差异。完整对照和修复后的前磨牙之间没有显著差异。完整牙齿的主要折裂模式为斜行折裂。对于有牙髓进入洞的前磨牙，无论是否修复，最常见的折裂模式为垂直折裂。用玻璃离子体和复合树脂修复合面进入洞可提供接近完整对照的抗折性，但修复后的牙齿折断时，大多无法修复。
