Rubo M H, el-Mowafy O
Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Int J Prosthodont. 1998 Jan-Feb;11(1):70-4.
The objective of this study was to determine radiopacity values of a group of resin-based cements and to compare them to those of enamel and dentin.
Three specimens 2.5 mm thick were prepared from each of 18 cements (nine chemical-cured and nine dual-cured). Three tooth sections 2.5 mm thick were cut from extracted molars. Specimens and tooth sections were divided into three matching groups. Following standard radiographic techniques, images of each group of specimens, along with an aluminum step wedge were obtained. Optical density readings for each material were determined with a transmission densitometer. Radiopacity values were subsequently calculated as equivalents of aluminum thickness.
Analysis of variance indicated significant differences in radiopacity values among the materials (P < 0.0001). Four dual-cured cements (Variolink, Geristore, Enforce, and Nexus) had radiopacity values significantly greater than that of enamel, while two (Choice and Adherence) had radiopacity values similar to enamel. For the remaining three dual-cured cements, Duolink had a radiopacity value significantly lower than that of enamel but higher than that of dentin, while both Lute-It and Resinomer had values similar to dentin. For the chemical-cured cements, five materials had radiopacity values significantly higher than enamel (Sealbond, Advance, Scotchbond, Cement-It, and Dyract-Cem), while two had values significantly lower than enamel but higher than dentin (Biomer and Panavia 21). The remaining two cements had radiopacity values significantly lower than dentin.
For a group of 18 resin-based cements, some had radiopacity values similar to or significantly lower than that of dentin.
本研究的目的是测定一组树脂基水门汀的射线不透性值，并将其与釉质和牙本质的射线不透性值进行比较。
从18种水门汀（9种化学固化型和9种双重固化型）中各制备3个厚度为2.5mm的试件。从拔除的磨牙上切取3个厚度为2.5mm的牙片。将试件和牙片分成3个匹配组。按照标准的放射照相技术，获取每组试件以及铝梯级楔形块的图像。用透射密度计测定每种材料的光密度读数。随后将射线不透性值计算为铝厚度的等效值。
方差分析表明，各材料间的射线不透性值存在显著差异（P<0.0001）。4种双重固化型水门汀（Variolink、Geristore、Enforce和Nexus）的射线不透性值显著高于釉质，而2种（Choice和Adherence）的射线不透性值与釉质相似。对于其余3种双重固化型水门汀，Duolink的射线不透性值显著低于釉质但高于牙本质，而Lute-It和Resinomer的射线不透性值均与牙本质相似。对于化学固化型水门汀，5种材料的射线不透性值显著高于釉质（Sealbond、Advance、Scotchbond、Cement-It和Dyract-Cem），而2种材料的射线不透性值显著低于釉质但高于牙本质（Biomer和Panavia 21）。其余2种水门汀的射线不透性值显著低于牙本质。
对于一组18种树脂基水门汀，有些水门汀的射线不透性值与牙本质相似或显著低于牙本质。
