Balaj Mădălina, Iacob Simona, Bud Marius, Delean Ada, Dudescu Mircea Cristian, Buduru Smaranda
Prosthetic Dentistry and Dental Materials Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania.
Conservative Odontology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania.
Med Pharm Rep. 2025 Apr;98(2):223-229. doi: 10.15386/mpr-2773. Epub 2025 Apr 29.
In recent years, dental trauma has been on the rise. The most common, regarding permanent dentition, are uncomplicated fractures (involving enamel or enamel and dentin) of the maxillary central incisors, followed by maxillary lateral incisors and mandibular central incisors. In anterior teeth, high impact stresses are frequently produced and because of this it is necessary that the restoration has a high fracture resistance. The aim of this study is to evaluate the influence of marginal cavity preparations (45° bevel and chamfer bevel) on the fracture resistance of teeth treated with direct composite resins.
For this study, 24 extracted mandibular incisors were used. All soft tissue debris and tartar were removed. During the study, the teeth were kept in saline to prevent dehydration. The teeth were divided into three groups of 8 teeth each. Group number 1 was used as a control and named C, in group number 2, named CH, incisors were prepared with a chamfer type of bevel, and in group number 3, named B45, incisors were prepared with a 45° bevel. After preparing all mandibular incisors, they were directly restored with nano-ceramic composite (Ceram.x® Duo, Dentsply Sirona). Subsequently, all three groups were fractured to determine the maximum compressive load using the Instron 3366 universal testing machine. To ensure a standardized fracturing process, all incisors were embedded in self-polymerizing acrylic resin up to the neck to replicate the conditions in the oral cavity.
The Student's T-test was employed for statistical analysis, revealing a statistically insignificant difference between the CH and B45 groups. Nonetheless, it was noted that the average values of maximum compressive loads in the chamfer bevel group were higher compared to those in the 45° bevel group, indicating its superior resistance to fracture. Additionally, the results of the fracture resistance test demonstrated that intact mandibular incisors are three times more resistant to fracture than mandibular incisors prepared and restored with dental bevels.
Intact teeth present a superior fracture resistance compared to teeth that have been subjected to trauma or carious processes, requiring coronal restoration; dental restorations made with a chamfer bevel marginal preparation withstand higher forces with improved fracture resistance compared to those made with a 45° bevel marginal preparation.
近年来，牙外伤呈上升趋势。就恒牙列而言，最常见的是上颌中切牙的单纯性骨折（累及釉质或釉质和牙本质），其次是上颌侧切牙和下颌中切牙。在前牙中，经常会产生高冲击应力，因此修复体必须具有高抗折性。本研究的目的是评估边缘洞形预备（45°斜面和倒角斜面）对直接复合树脂治疗牙齿抗折性的影响。
本研究使用了24颗拔除的下颌切牙。去除所有软组织碎屑和牙石。在研究过程中，将牙齿保存在盐水中以防止脱水。将牙齿分为三组，每组8颗。第1组用作对照组，命名为C；第2组命名为CH，切牙制备成倒角型斜面；第3组命名为B45，切牙制备成45°斜面。制备完所有下颌切牙后，用纳米陶瓷复合材料（Ceram.x® Duo，登士柏西诺德）直接修复。随后，使用Instron 3366万能试验机对所有三组进行折断试验，以确定最大压缩载荷。为确保折断过程标准化，将所有切牙嵌入自凝丙烯酸树脂至颈部，以模拟口腔环境。
采用学生t检验进行统计分析，结果显示CH组和B45组之间无统计学显著差异。然而，值得注意的是，倒角斜面组的最大压缩载荷平均值高于45°斜面组，表明其抗折性更强。此外，抗折性测试结果表明，完整的下颌切牙的抗折性是经过牙斜面制备和修复的下颌切牙的三倍。
与遭受外伤或龋病过程并需要冠修复的牙齿相比，完整牙齿具有更强的抗折性；与采用45°斜面边缘预备制作的牙科修复体相比，采用倒角斜面边缘预备制作的牙科修复体能够承受更高的力，抗折性更好。
