Objectives

The effects of different surface treatments on cyclic fatigue strengths of computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia implants and its mechanisms were evaluated.

Material and methods

One-piece cylindrical screw-type zirconia (Y-TZP) implants with diameters of 4.1-mm were fabricated using CAD/CAM technique; they were divided into four groups according to the type of surface treatment: (i) sintering (control group, CTRL), (ii) sandblasting (SB), (iii) sandblasting and etching with an experimental hot etching solution (SB-ST), and (iv) sandblasting and etching with hydrofluoric acid (SB-HF). The surface morphology and roughness of the implants were evaluated. Tetragonal to monoclinic transformation was measured on the surface by micro Raman spectroscopy. Static and fatigue tests were carried out at room temperature following the ISO 14801:2014 Standard. The cyclic fatigue strength of each group was determined using the staircase method. Specimens that survived the fatigue test were statically loaded to measure the residual fracture strength.

Results

Among the four groups, SB-HF exhibited the highest surface roughness. Compared with the CTRL group, the surface monoclinic content was higher after all three types of surface treatments, amongst which, SB-HF had the highest content (39.14%), significantly more than the other three groups (P < 0.01). The cyclic fatigue strengths of CTRL, SB, SB-ST, and SB-HF implants were 530 N, 662.5 N, 705 N, and 555 N, respectively. The fracture strength after fatigue loading was higher than that before fatigue loading with no significant difference (P＞0.05).

Conclusions

SB and SB-ST remarkably enhanced the fatigue resistance of zirconia implants, while SB-HF did not. One-piece 4.1-mm diameter CAD/CAM zirconia implants have sufficient durability for application in dental implants.

中文翻译：

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不同表面处理对一件式CAD / CAM氧化锆植入物的循环疲劳强度的影响

目标

评估了不同表面处理对计算机辅助设计和计算机辅助制造（CAD / CAM）氧化锆植入物的循环疲劳强度的影响及其机理。

材料与方法

采用CAD / CAM技术制造了直径为4.1mm的一件式圆柱螺钉型氧化锆（Y-TZP）植入物。根据表面处理的类型将它们分为四组：（i）烧结（对照组，CTRL），（ii）喷砂（SB），（iii）喷砂和使用实验性热蚀刻溶液（SB-ST）进行蚀刻；以及（iv）喷砂和氢氟酸（SB-HF）蚀刻。评价了植入物的表面形态和粗糙度。通过显微拉曼光谱法在表面上测定了从四方到单斜相的转变。静态和疲劳测试是在室温下按照ISO 14801：2014标准进行的。使用阶梯法确定每组的循环疲劳强度。

结果

在四组中，SB-HF表现出最高的表面粗糙度。与CTRL组相比，三种表面处理后的表面单斜晶含量均较高，其中SB-HF的含量最高（39.14％），明显高于其他三组（P <0.01）。CTRL，SB，SB-ST和SB-HF植入物的循环疲劳强度分别为530 N，662.5 N，705 N和555N。疲劳载荷后的断裂强度高于疲劳载荷前的断裂强度，差异无统计学意义（P＞ 0.05）。

结论

SB和SB-ST显着增强了氧化锆植入物的抗疲劳性，而SB-HF则没有。直径为4.1毫米的一体式CAD / CAM氧化锆植入物具有足够的耐用性，可用于牙科植入物。