Private practice, Kenmore, Wash.
Professor, Department of Restorative Dentistry, University of Washington School of Dentistry, Seattle, Wash.
J Prosthet Dent. 2024 Jan;131(1):100.e1-100.e5. doi: 10.1016/j.prosdent.2023.09.018. Epub 2023 Oct 20.
The necessity of roughening the intaglio surface of zirconia crowns to achieve adequate retention is unclear.
The purpose of this clinical simulation study was to evaluate the retention of airborne-particle-abraded and nonabraded monolithic zirconia crowns using 3 different cement types.
Extracted human molars were used and prepared with a 10-degree taper. Impressions were made of the prepared teeth with a polyvinyl siloxane (PVS) material, and dies were made with Type 4 gypsum. Each die was scanned with a NobelProcera 1G Scanner, and the standard tessellation language (STL) files were transferred electronically to the Nobel Biocare production site, where a bar was added virtually on top of each crown and parameters were set for milling. Seventy-two Procera zirconia crowns were generated, of which half were airborne-particle abraded on the intaglio surface with 50-µm alumina particles at 400 to 500 kPa for 15 seconds. The other 36 received no intaglio treatment other than cleaning. Both groups of 36 crowns were divided into 3 subgroups of 12 specimens. The area of each preparation was calculated using a computer-aided design software program. The specimens were distributed to attain similar mean surface areas among the cementation groups. The crowns were cemented onto the specimen with a controlled force of 196 N. The 3 cements used were self-adhesive, modified resin RelyX Unicem Aplicap, resin-modified glass ionomer RelyX Luting, and a composite resin, Panavia F2.0 with ED Primer A & B. All specimens were thermocycled (5 °C to 55 °C) for 5000 cycles and then removed axially with a universal testing machine (Instron Model 5585H) at a crosshead speed of 0.5 mm/min. The removal force was recorded, and stress of dislodgement was calculated for each crown. A 2-way analysis of variance was used for statistical analyses. The type of failure was analyzed with the chi-squared test of association for independent samples (α=.05 for all tests).
The mean dislodging force for crowns with airborne-particle abraded intaglio was 5.4 MPa, which was statistically greater than the mean of 3.2 MPa for nonabraded specimens (P<.001). No significant differences related to the dislodging stresses were detected among the 3 cements (P=.109). The mode of failure was similar whether abraded or not, with 50% of specimens retaining cement in the crown after separation.
Alumina airborne-particle abrasion of the intaglio of zirconia to create surface roughness is beneficial in retaining the crowns, regardless of the cement type. The nonabraded crowns demonstrated significantly lower retentive stress with crown removal. The principal mode of failure was similar whether the zirconia intaglio was airborne-particle abraded or not. The most common mode of failure (>50% of specimens) was at least three-fourths of the cement remaining within the crown.
为了获得足够的固位力而对氧化锆冠的凹面进行粗化的必要性尚不清楚。
本临床模拟研究的目的是使用 3 种不同的粘固剂评估经气载粒子喷砂和未经喷砂的整体氧化锆冠的固位力。
使用人磨牙进行实验，制备 10 度锥度。用聚硅氧烷（PVS）材料对预备牙进行印模，用 4 型石膏制作印模。每个印模均用 NobelProcera 1G 扫描仪进行扫描，并将标准 tessellation language（STL）文件以电子方式传输到 Nobel Biocare 生产现场，在每个冠的顶部虚拟添加一个条，并设置铣削参数。生成了 72 个 Procera 氧化锆冠，其中一半的凹面用 50-µm 氧化铝颗粒在 400 至 500 kPa 下喷砂处理 15 秒。另一半则除了清洁外没有进行任何凹面处理。这两组 36 个冠被分为 3 组，每组 12 个样本。使用计算机辅助设计软件程序计算每个预备体的面积。分配样本以在粘固剂组之间获得相似的平均表面积。将冠以 196 N 的受控力粘接到样本上。使用的 3 种粘固剂分别是自粘的、改良的树脂 RelyX Unicem Aplicap、树脂改性的玻璃离子体 RelyX Luting，以及一种复合材料 Panavia F2.0 with ED Primer A & B。所有样本均在 5°C 至 55°C 之间进行 5000 次热循环，然后用万能试验机（Instron Model 5585H）以 0.5mm/min 的十字头速度轴向取出。记录去除力，并计算每个冠的脱位应力。使用双向方差分析进行统计分析。使用独立样本的卡方检验关联分析（所有检验的α值均为 0.05）分析失效类型。
经气载粒子喷砂处理的凹面氧化锆冠的平均脱位力为 5.4 MPa，明显大于未经喷砂处理的 3.2 MPa（P<.001）。在 3 种粘固剂之间未检测到与脱位应力相关的显著差异（P=.109）。无论是喷砂还是未喷砂，失效模式都相似，50%的样本在分离后仍保留在冠内的粘固剂。
无论粘固剂类型如何，用氧化铝气载粒子对氧化锆的凹面进行喷砂以增加表面粗糙度都有利于保持冠的固位。未喷砂的冠显示出明显较低的固位力，在去除冠时。主要失效模式相似，无论氧化锆凹面是否进行气载粒子喷砂。最常见的失效模式（>50%的样本）是至少有四分之三的粘固剂保留在冠内。
