METHODS: Forty-eight implants (4.3 mm diameter) were divided into four groups (n = 12) to support 2-unit mandibular premolar cantilevers with two different materials (Zr-TiB vs. PFM-GA) and two connection types (IBJ vs. IC). Tested groups were as follows: (1) IBJ/Zr-TiB; (2) IBJ/PFM-GA; (3) IC/Zr-TiB; and (4) IC/PFM-GA. Specimens were thermomechanical aged (1,200,000 cycles, 98 N, 5-55°C) with occlusal axial load on the pontic. Catastrophic and non-catastrophic events were registered, and removal torque values measured before and after aging. Specimens surviving aging were subjected to loading until failure. Survival, total complication rates, torque loss (%), and bending moments were calculated.
RESULTS: From 48 specimens, 38 survived aging. Survival rates significantly varied from 16.7% (IC/PFM-GA) to 100% (IBJ/Zr-TiB; IBJ/PFM-GA; IC/Zr-TiB) (p < .01). Internal conical connection revealed significantly higher torque loss (IC/ZrTiB - 67%) compared to internal butt-joint (IBJ/Zr-TiB - 44%; IBJ/PFM-GA - 46%) (p < .01). Bending moments were higher in internal butt-joint connections than in internal conical (p < .05).
CONCLUSIONS: Two-unit posterior implant-supported cantilever FDPs replacing mandibular premolars composed of monolithic zirconia on titanium-base abutments demonstrated higher mechanical stability compared to porcelain-fused-to-metal on castable gold abutments in this in vitro study. The internal conical connection combined with porcelain-fused-to-metal on gold abutments revealed a high number of failures; therefore, their clinical use may be considered cautiously for this indication.
方法:将48个植入物(直径4.3mm)分为四组(n=12),以两种不同的材料(Zr-TiBvs.PFM-GA)和两种连接类型(IBJ与IC)。试验组如下:(1)IBJ/Zr-TiB;(2)IBJ/PFM-GA;(3)IC/Zr-TiB;和(4)IC/PFM-GA。样品进行了热机械老化(1,200,000次循环,98N,5-55°C),在桥体上施加咬合轴向载荷。记录了灾难性和非灾难性事件,以及老化前后测量的去除扭矩值。对老化存活的样品进行加载直至失效。生存,总并发症发生率,扭矩损失(%),并计算了弯矩。
结果:来自48个样本,38岁幸存下来。存活率从16.7%(IC/PFM-GA)到100%(IBJ/Zr-TiB;IBJ/PFM-GA;IC/Zr-TiB)显著变化(p<.01)。与内部对接接头(IBJ/Zr-TiB-44%;IBJ/PFM-GA-46%)相比,内部锥形连接显示出显著更高的扭矩损失(IC/ZrTiB-67%)(p<.01)。内部对接连接的弯矩高于内部圆锥形连接的弯矩(p<.05)。
结论:在这项体外研究中,两单元后种植体支撑悬臂FDP替代了钛基基基上由整体氧化锆组成的下颌前磨牙,与可铸造金基上的瓷熔接金属相比,具有更高的机械稳定性。内部圆锥形连接与金基台上的瓷熔金属结合显示出大量故障;因此,对于该适应症,可以谨慎考虑其临床使用。