el-Mowafy O M, Fenton A H, Forrester N, Milenkovic M
Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Ont., Canada.
J Prosthet Dent. 1996 Nov;76(5):524-9. doi: 10.1016/s0022-3913(96)90012-8.
This study investigated the effect of varying crown preparation taper and height on the retention of metal ceramic crowns cemented with resin cements. In part 1, 32 extracted molars were divided into four groups. All groups received complete-veneer crown preparations, two with a 12-degree wall angle and two with a 35-degree wall angle. Crowns were cemented with zinc phosphate and dentin-bonded resin cements. After 24 hour water storage at 37 degrees C, the crowns were separated in tension. Crowns cemented with zinc phosphate were cleaned and recemented with another dentin-bonded resin cement and after similar storage, the crowns were separated. Mean separation forces of resin-cemented crowns were higher than those of crowns cemented with zinc phosphate cement. Mean separation force of 35-degree crowns cemented with one dentin-bonded resin cement was found to be significantly higher than for the 12-degree crowns cemented with zinc phosphate cement. In part II, 32 extracted molars were divided into two groups of complete-veneer crown preparations (group I preparations were 3 mm high and group II were 5 mm high). Crowns for all teeth were cast and cemented with zinc phosphate. After 48 hours' water storage at 37 degrees C, the crowns were separated in tension. Crowns and teeth were then cleaned and each group was subdivided into 2 equal subgroups. In one subgroup of teeth with 3 mm and in one with 5 mm high preparations, the crowns were recemented with one of the two resin cement systems and the other two subgroups were recemented with the other resin cement. After 48-hour water storage, the crowns were separated. Mean separation forces of the resin-cemented crowns were greater than those of crowns cemented with zinc phosphate. Also, mean separation force of 3 mm crowns cemented with one resin cement was significantly greater than the 5 mm crowns cemented with zinc phosphate. Cohesive dentin fracture on separation was observed with some resin-cemented crowns but never with crowns cemented with zinc phosphate.
本研究调查了不同的牙冠预备锥度和高度对用树脂水门汀粘结的金属烤瓷冠固位力的影响。在第一部分，32颗拔除的磨牙被分为四组。所有组均进行全冠预备，两组的壁角为12度，两组的壁角为35度。用磷酸锌水门汀和牙本质粘结树脂水门汀粘结牙冠。在37℃下储存24小时后，对牙冠进行拉伸分离。用磷酸锌粘结的牙冠进行清洁，并用另一种牙本质粘结树脂水门汀重新粘结，在类似储存后，对牙冠进行分离。树脂粘结牙冠的平均分离力高于用磷酸锌水门汀粘结的牙冠。发现用一种牙本质粘结树脂水门汀粘结的35度牙冠的平均分离力显著高于用磷酸锌水门汀粘结的12度牙冠。在第二部分，32颗拔除的磨牙被分为两组进行全冠预备（第一组预备高度为3mm，第二组为5mm）。所有牙齿的牙冠均铸造并用磷酸锌粘结。在37℃下储存48小时后，对牙冠进行拉伸分离。然后清洁牙冠和牙齿，每组再分为两个相等的亚组。在一个3mm高预备的牙齿亚组和一个5mm高预备的牙齿亚组中，用两种树脂水门汀系统中的一种重新粘结牙冠，另外两个亚组用另一种树脂水门汀重新粘结。在储存48小时后，对牙冠进行分离。树脂粘结牙冠的平均分离力大于用磷酸锌粘结的牙冠。此外，用一种树脂水门汀粘结的3mm牙冠的平均分离力显著大于用磷酸锌粘结的5mm牙冠。在一些树脂粘结牙冠分离时观察到牙本质粘结性骨折，但在用磷酸锌粘结的牙冠中从未观察到。
