Professor and Consultant, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Associate Professor and Consultant, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
J Prosthet Dent. 2018 Feb;119(2):263-269. doi: 10.1016/j.prosdent.2017.03.013. Epub 2017 May 26.
The detrimental effect of extruded excess cement on peri-implant tissue has been well documented. Although several techniques have been proposed to reduce this effect by decreasing the amount of extruded cement, how the space size of the abutment screw access channel (SAC) affects the amount of extruded cement and marginal accuracy is unclear.
The purpose of this in vitro study was to evaluate the effect of the size of the unfilled space of the abutment SAC on the amount of extruded excess cement and the marginal accuracy of zirconia copings.
Twelve implant replicas and corresponding standard abutments were attached and embedded in acrylic resin blocks. Computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings with a uniform 30-μm cement space were fabricated by 1 dental technician using the standard method. The copings were temporarily cemented 3 times at different sizes of the left space of the SAC as follows: the nonspaced group (NS), in which the entire SAC was completely filled, the 1-mm-spaced group (1MMS), and the 2-mm-spaced group (2MMS). Abutments and crowns were ultrasonically cleaned, steam cleaned, and air-dried. The excess cement was collected and weighed. To measure the marginal accuracy, 20 measurements were made every 18 degrees along the coping margin at ×300 magnification and compared with the pre-cementation readings. One-way ANOVA was calculated to determine whether the amount of extruded excess cement differed among the 3 groups, and the Tukey test was applied for multiple comparisons (α=.05).
The mean weights (mg) of extruded excess cement were NS (33.53 ±1.5), 1MMS (22.97 ±5.4), and 2MMS (15.17 ±5.9). Multiple comparisons showed significant differences in the amount of extruded excess cement among the 3 test groups (P<.001). The mean marginal discrepancy (μm) of the pre-cemented group (29.5 ±8.2) was significantly different (P<.01) from that of the NS (72.3 ±13.7), the 1MMS (70.1 ±19), and the 2MMS group (70.1 ±18.8). No significant differences were found in marginal accuracy among the 3 test groups (P=.942).
Within the limitations of this in vitro study, leaving a 2-mm space in the SAC reduced the amount of extruded excess cement by 55% in comparison with the nonspaced abutments. However, no effect was found on the marginal accuracy of zirconia copings.
挤出过多的水泥对种植体周围组织的有害影响已得到充分证实。尽管已经提出了几种技术来减少挤出的水泥量，从而降低这种影响，但是，尚未明确基台螺丝通道（SAC）的未填充空间大小如何影响挤出的水泥量和边缘精度。
本体外研究的目的是评估基台 SAC 未填充空间的大小对挤出过多的水泥量和氧化锆修复体边缘精度的影响。
将 12 个种植体模型和相应的标准基台连接并嵌入丙烯酸树脂块中。由 1 名牙科技术人员使用标准方法通过计算机辅助设计和计算机辅助制造（CAD-CAM）制造具有均匀 30μm 水泥空间的氧化锆修复体。将修复体暂时在 SAC 的左侧空间的不同尺寸下临时粘接 3 次，具体如下：无间隙组（NS），整个 SAC 完全填充；1mm 间隙组（1MMS）；2mm 间隙组（2MMS）。用超声波清洗、蒸汽清洗和风干基台和冠。收集并称重多余的水泥。为了测量边缘精度，在修复体边缘每隔 18 度进行 20 次测量，放大倍数为×300，并与预粘接时的读数进行比较。采用单因素方差分析（ANOVA）来确定 3 组之间挤出的多余水泥量是否存在差异，并用 Tukey 检验进行多重比较（α=.05）。
NS 组（33.53±1.5）、1MMS 组（22.97±5.4）和 2MMS 组（15.17±5.9）的挤出多余水泥量的平均值（mg）分别为 NS、1MMS 和 2MMS。多重比较显示 3 组测试之间挤出的多余水泥量存在显著差异（P<.001）。预粘接组的平均边缘差异（μm）（29.5±8.2）与 NS（72.3±13.7）、1MMS（70.1±19）和 2MMS 组（70.1±18.8）相比差异有统计学意义（P<.01）。3 组测试之间的边缘精度无显著差异（P=.942）。
在本体外研究的限制范围内，与无间隙基台相比，在 SAC 中留出 2mm 的空间可将挤出的多余水泥量减少 55%。然而，对氧化锆修复体的边缘精度没有影响。
