Loma Linda University School of Dentistry, Loma Linda, CA, USA.
Oper Dent. 2010 May-Jun;35(3):314-23. doi: 10.2341/09-180-L.
This study determined if a standardized condensation force and dwell time per condensation pressure point could reliably bond new amalgam to older amalgam without applying extrinsic Hg. A stabilization jig was created to hold 15 friction-fit 1-inch diameter (25 mm) cylindrical resin specimen blocks face up with cavities drilled to contain the condensed primary amalgam (Valiant PhD-XT). Freshly mixed secondary amalgam (Valiant PhD-XT) was condensed against the primary amalgam surfaces through the 3.5-mm-diameter central holes of specially fabricated split-ring molds. The 15 disks fit snugly within the holes of the stabilization jig tray. Condensation was with a consistent, calibrated force of 22.5 MPa (4 lbs/0.79 mm2) applied with a spring-loaded amalgam carrier custom adapted with a 1-mm-diameter stainless steel condenser tip. Secondary amalgam additions were built up in three 1-mm thick increments with a pattern of eight 22.5 MPa two-second condenser strokes per incremental layer. Shear-bond testing with a 1-mm/minute crosshead speed occurred 24-hours post-condensation. One-way analysis of variance statistical analysis was conducted to analyze the results. The mean shear-bond forces (MPa, N = 15) found were: Control 28.1 +/- 5, 15 minutes 31 +/-5, one hour 10.7 +/-4 (N = 30), one day 25.5 +/- 4, one week 25.2 +/- 4, two months 25.1 +/- 5 and seven years 24.7 +/- 4. Under the condensation pressures used in the current study, the addition of new amalgam to smooth previously set amalgam surfaces, not including the one-hour group, up to seven years old, resulted in shear-bond forces not statistically different (p = 0.05) from the intact control. Virtually all (94%) of the bonds tested, except for the one-hour sample, resulted in cohesive rather than adhesive failures except those of the one-hour sample. Forty percent bond strengths of the controls were achieved when only 5.6 MPa (1 lb/0.79 mm2) and 14 MPa (2.5 lb/0.79 mm2) condensation pressures were used.
本研究旨在确定标准化的冷凝力和每个冷凝压力点的停留时间是否可以在不施加外源性汞的情况下可靠地将新的银汞合金粘结到旧的银汞合金上。创建了一个稳定夹具，将 15 个摩擦配合的 1 英寸直径（25 毫米）圆柱形树脂标本块面朝上放置，标本块上钻有孔以容纳冷凝的初级银汞合金（Valiant PhD-XT）。新鲜混合的次级银汞合金（Valiant PhD-XT）通过特制的分体环模具的 3.5 毫米直径中心孔压在初级银汞合金表面上。15 个圆盘紧密贴合在稳定夹具托盘的孔内。冷凝过程中施加了一致的、经过校准的 22.5 MPa（4 磅/0.79 毫米 2 ）的力，使用带有 1 毫米直径不锈钢冷凝尖端的弹簧加载银汞合金载体进行。次级银汞合金的添加量增加了三层，每层厚度为 1 毫米，每层采用 8 次 22.5 MPa 两秒冷凝行程的模式。24 小时冷凝后，以 1 毫米/分钟的十字头速度进行剪切粘结测试。进行了单向方差统计分析来分析结果。找到的平均剪切粘结力（MPa，N=15）如下：对照组 28.1±5，15 分钟 31±5，1 小时 10.7±4（N=30），1 天 25.5±4，1 周 25.2±4，2 个月 25.1±5，7 年 24.7±4。在当前研究中使用的冷凝压力下，将新的银汞合金添加到之前凝固的银汞合金表面上，不包括 1 小时组，直到 7 年，其剪切粘结力与完整对照组没有统计学差异（p=0.05）。除了 1 小时组外，除了 1 小时组外，几乎所有（94%）测试的粘结都导致了内聚性而不是粘质性失效。当仅使用 5.6 MPa（1 磅/0.79 毫米 2 ）和 14 MPa（2.5 磅/0.79 毫米 2 ）的冷凝压力时，对照组的 40%的粘结强度得以实现。
