Department of Operative Dentistry, School of Dental Medicine, Tsurumi University, Tsurumi, Tsurumi-ku, Yokohama, Japan.
Biomed Mater Eng. 2022;33(4):259-268. doi: 10.3233/BME-211307.
Polymerization stress is a major problem in dental resin composite restorations. Two indentation fracture methods can be applied to evaluate the stress, however, they often calculate different values.
To compare polymerization stresses of dental composites determined by the two methods.
Glass disks with a central hole were used. Two indentation fracture methods (Methods 1 and 2) were employed to determine the polymerization stresses of low-shrinkage and bulk-fill composites. Method 1: Cracks were made in the glass surface at 300 μm from the hole. The hole was filled with the composite. Polymerization stresses at 30 min after filling were calculated from the lengths of crack extension. Method 2: The hole was filled with the composite. Cracks were introduced in the glass at 1,000 μm from the hole at 30 min after the polymerization and the stresses were calculated from the crack lengths. Stresses at composite-glass bonded interface were calculated from the stress values obtained by the two methods.
The bulk-fill composite generated the smallest interfacial stress, and Method 1 revealed lower values than Method 2.
The composites yielded relatively small stresses. Method 1 calculated smaller stress values, possibly affected by the lower threshold stress intensity factor.
聚合应力是牙科树脂复合材料修复体的一个主要问题。有两种压痕断裂方法可用于评估这种应力，但它们通常会计算出不同的值。
比较两种方法测定牙科复合材料聚合应力的差异。
使用带有中心孔的玻璃圆盘。采用两种压痕断裂方法（方法 1 和方法 2）来测定低收缩和大体积充填复合材料的聚合应力。方法 1：在距孔 300 μm 的玻璃表面制造裂缝。用复合材料填充孔。从裂缝扩展的长度计算填充后 30 分钟的聚合应力。方法 2：用复合材料填充孔。在聚合后 30 分钟，在距孔 1000 μm 的玻璃上引入裂缝，并从裂缝长度计算应力。从两种方法获得的应力值计算复合材料-玻璃结合界面的应力。
大体积充填复合材料产生的界面应力最小，方法 1 显示的值低于方法 2。
复合材料产生的应力相对较小。方法 1 计算出的应力值较小，可能受较低的门槛值影响。
