Purpose

Intraoral adjustments of monolithic zirconia (MZ) necessitate intraoral grinding and polishing procedures, causing surface topography changes. The effect of various polishing and glazing procedures on surface roughness, topographical and phase changes of CoCr compared to zirconia, and assessment of the wear of the opposing dentition has been evaluated in this study.

Materials and methods

One group of square Cobaltchromium (CoCr) and four groups of sintered and polished zirconia specimens (12 × 12 × 1mm) were fabricated (N = 5, n = 8) using Cobaltchromium or yttria-stabilized zirconia (ZrO2, Y2O3) blocks (ZENTROSTAR Zr Translucent; Wieland Dental + Technik). Each of the four zirconia groups was treated differently, one group was glazed (G), one was left unglazed (UG), two groups were polished, one using silicon carbide polishers (BG) and one with diamond-impregnated ceramic polisher kit (CG). All specimens were thereafter subjected to chewing simulation using enamel cusps (1’200’000 cycles, 49N force and 1.67 Hz loading frequency). Topographical changes were evaluated considering (a) weight (digital scale), (b) volume loss (digital microscope), (c) vertical height loss (digital microscope), (d) surface roughness (Ra, profilometer), and (e) mean roughness depth (Rz, profilometer). In addition the volume loss (digital microscope) of the used corresponding enamel cusps was measured. The surface roughness, topographical changes and antagonist wear of enamel cusps were measured. Statistical analysis was performed using the statical software R and the kruskal-wallis rank sum test and posthoc pairwise comparisons (a = 0.05).

Results

The mean surface roughness (μm) difference (ΔRa) was lowest for UG (−0.014 ± 0.007) and the highest for CG (−0.806 ± 0.172) (UG^a < CoCr^b < BG^c < G^a,d < CG^e). UG showed the lowest surface peak roughness (μm) difference (ΔRz) −0.316 ± 0.084 and CG the highest (−3.691 ± 0.369) (UG^a < CoCr^b < BG^c < G^a,d < CG^e). Material weight loss (ΔW) ranged between −0.005 ± 0.0001 and −0.000 ± 0.000 g (CoCr^a < UG^a,b < CG^b < BG^b < G^b) compared to baseline, while the volume loss (ΔV) was between −21 ± 52 × 10⁶ and 58 ± 36 × 10⁶ μm3 (CoCr^a < BG^a < UG^a < CG^a < G^a). The vertical height loss (ΔVH) was highest for UG (−12.067 ± 11.624) and lowest for G −0.033 ± 0.034 μm (G^a < CoCr^a,b < CG^c < BG^a,c,d < UG^a,b,d). As for the volume loss (ΔV) of the corresponding enamel cusps, no significant differences could be measured (BG^a < UG^a < G^a < CG^a < CoCr^a), therefore surface treatment did not affect the wear of the enamel antagonist.

Conclusion

CoCr and highly polished monolitic zirconia produced less surface roughness and similar antagonist wear compared to glazed or unglazed zirconia. CoCr and highly polished monolitic zirconia can be considered as a good choice regarding the mechanical wear behaviour of materials and their corresponding enamel antagonist.

中文翻译：

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抛光和上光程序后，整体氧化锆和CoCr对人体牙釉质的磨损分析和形貌特性。

目的

整体氧化锆（MZ）的口内调整需要进行口内研磨和抛光程序，从而引起表面形貌变化。与氧化锆相比，各种抛光和上釉程序对CoCr的表面粗糙度，形貌和相变的影响以及对牙列磨损的评估均已进行了评估。

材料和方法

使用钴铬或氧化钇稳定的氧化锆（ZrO2，Y2O3）块（ZENTROSTAR）制作了一组方形钴铬（CoCr）和四组烧结和抛光的氧化锆样品（12×12×1mm）（N = 5，n = 8）。 Zr半透明； Wieland Dental + Technik）。四个氧化锆组分别进行了不同的处理，一组上釉（G），一组未上釉（UG），两组进行了抛光，一组使用碳化硅抛光机（BG），另一组使用浸有金刚石的陶瓷抛光机套件（CG） ）。此后，所有样品均使用搪瓷牙尖进行咀嚼模拟（1'200'000个循环，49N的力和1.67 Hz的加载频率）。考虑以下因素评估地形变化：（a）重量（数字刻度），（b）体积损失（数字显微镜），（c）垂直高度损失（数字显微镜），（d）表面粗糙度（Ra，轮廓仪），（e）平均粗糙度（Rz，轮廓仪）。另外，测量所使用的相应牙釉质尖头的体积损失（数字显微镜）。测量了牙釉质尖头的表面粗糙度，形貌变化和拮抗剂磨损。使用静态软件R和kruskal-wallis秩和检验和事后成对比较（a = 0.05）进行统计分析。

结果

UG的平均表面粗糙度（μm）差异（ΔRa）最低（-0.014±0.007），而CG的最高（-0.806±0.172）（UG ^a  <CoCr ^b  <BG ^c  <G ^a，d  <CG ^e） 。UG表现出最低的表面峰粗糙度（μm）差（ΔRz）-0.316±0.084，而CG表现出最高的表面粗糙度（-Rm）（-3.691±0.369）（UG ^a  <CoCr ^b  <BG ^c  <G ^a，d  <CG ^e）。材料重量损失（ΔW）在-0.005±0.0001和-0.000±0.000 g之间（CoCr ^a  <UG ^a，b  <CG ^b  <BG ^b  <G ^b）与基线相比，而体积损失（ΔV）为-21之间±52×10 ⁶和58×10±36 ⁶ μm3（钴铬^一个 <BG^一个 <UG^一个 <CG^一个 的<g^一个）。UG的垂直高度损失（ΔVH）最高（-12.067±11.624），G -0.033±0.034μm最低（G ^a  <CoCr ^a，b  <CG ^c  <BG ^a，c，d  <UG ^{a，b d}）。至于相应牙釉质尖头的体积损失（ΔV），则无法测量到显着差异（BG ^a  <UG ^a  <G ^a  <CG ^a  <CoCr ^a），因此表面处理不会影响搪瓷拮抗剂的磨损。

结论

与上釉或未上釉的氧化锆相比，CoCr和高度抛光的单晶氧化锆产生的表面粗糙度较小，拮抗剂磨损类似。考虑到材料及其相应的搪瓷拮抗剂的机械磨损性能，CoCr和高度抛光的单晶氧化锆可以被视为一个不错的选择。