Ozturk A Nilgun, Belli Sema, Eskitascioglu Gurcan
Department of Prosthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey.
J Prosthet Dent. 2004 Mar;91(3):253-7. doi: 10.1016/j.prosdent.2004.01.003.
The degree to which pulpal pressure may affect bond strength of complete cast crowns is unknown.
The aim of this in vitro study was to evaluate the effect of simulated pulpal pressure on the tensile bond strength of complete cast crowns luted with 2 different cements.
Forty-eight human mandibular canine teeth were cleaned and stored in saline solution. The crowns were prepared by 1 investigator, and standardization of the preparation was accomplished by fixing a dental handpiece in a parallelometer. Uniform grooves, 0.5 mm in depth, were prepared with burs with depth guides. The complete crowns were prepared with a 0.5-mm shoulder margin. Teeth were randomly divided into 2 groups of 24 teeth each (Group I and Group II). In Group I, bonding and tensile test procedures of the teeth were carried out under simulated pulpal pressure (15 cm of saline solution). In Group II, simulated pulpal pressure was not used. The roots were removed 1 mm below the cementoenamel junction to create direct communication with the pulp chamber. The remaining pulpal tissues were carefully removed, and crowns were embedded in acrylic resin. The acrylic resin was then penetrated by a stainless steel tube that connected the pulp chamber and the barrel of a disposable plastic 5-ml syringe. The pulp chambers were filled with physiological saline solution under elevated pressure to locate the area of greatest permeability on the dentinal surface. Crowns were cast (Co-Cr alloy) with a 20-mm bar to allow testing of the bond strength. Each of the 2 groups were further divided into 2 luting cement groups of 12 each (Group I, A and B, and Group II, A and B). Group IA/IIA and Group IB/IIB specimens were luted with a polycarboxylate luting cement (Poly-F Plus) and an adhesive luting cement (Superbond C&B), respectively. After storage in distilled water for 24 hours, all specimens were subjected to a tensile bond test in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The maximum load at fracture (Newton) was recorded. The results were then evaluated with 2-way analysis of variance and Tukey's honestly significant difference tests (alpha=.05).
Simulated pulpal pressure increased the bond strength of cast complete crowns cemented with an adhesive luting agent (P=.01). No significant difference was found in the bond strength of complete cast crowns cemented with polycarboxylate cement with or without pulpal pressure. Superbond C&B adhesive luting agent showed significantly higher bond strength values for Group I (388.9+/-32.7) and Group II (300.9+/-66.8), when compared with polycarboxylate cement for Group I (221.3+/-17.3) and Group II (186.8+/-38.5) (P=.001).
Simulated pulpal pressure had a positive effect on the retention of complete cast crowns when cemented with Superbond C&B adhesive luting agent. Superbond C&B significantly increased the retention of crowns in either the presence or absence of pulpal pressure.
牙髓压力对全冠铸造冠粘结强度的影响程度尚不清楚。
本体外研究的目的是评估模拟牙髓压力对用两种不同粘结剂粘结的全冠铸造冠拉伸粘结强度的影响。
48颗人下颌尖牙经清洁后保存在盐溶液中。由1名研究人员制备牙冠，并通过将牙科手机固定在平行仪中来完成制备的标准化。使用带深度导向的车针制备深度为0.5mm的均匀凹槽。全冠制备有0.5mm的肩台边缘。牙齿随机分为2组，每组24颗牙（I组和II组）。在I组中，在模拟牙髓压力（15cm盐溶液）下进行牙齿的粘结和拉伸测试程序。在II组中，未使用模拟牙髓压力。在牙骨质釉质界下方1mm处去除牙根，以与牙髓腔建立直接连通。小心去除剩余的牙髓组织，然后将牙冠嵌入丙烯酸树脂中。然后用一根不锈钢管穿透丙烯酸树脂，该不锈钢管连接牙髓腔和一次性塑料5ml注射器的针筒。在高压下向牙髓腔中注入生理盐水，以确定牙本质表面渗透性最大的区域。用20mm的杆铸造冠（钴铬合金），以便测试粘结强度。2组中的每组再进一步分为2个粘结剂组，每组12个（I组，A和B，以及II组，A和B）。IA/IIA组和IB/IIB组标本分别用聚羧酸粘结剂（Poly-F Plus）和粘结性粘结剂（Superbond C&B）粘结。在蒸馏水中储存24小时后，所有标本在万能试验机上以0.5mm/min的十字头速度进行拉伸粘结测试，直至破坏。记录断裂时的最大载荷（牛顿）。然后用双向方差分析和Tukey真实显著性差异检验（α=0.05）对结果进行评估。
模拟牙髓压力增加了用粘结性粘结剂粘结的铸造全冠的粘结强度（P=0.01）。在有或没有牙髓压力的情况下，用聚羧酸粘结剂粘结的全冠铸造冠的粘结强度没有显著差异。与I组（221.3±17.3）和II组（186.8±38.5）的聚羧酸粘结剂相比，Superbond C&B粘结性粘结剂在I组（388.9±32.7）和II组（300.9±66.8）中显示出显著更高的粘结强度值（P=0.001）。
当用Superbond C&B粘结性粘结剂粘结时，模拟牙髓压力对全冠铸造冠的固位有积极影响。无论有无牙髓压力，Superbond C&B都显著提高了冠的固位力。
