Forberger Nicole, Göhring Till N
Clinic of Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University of Zurich, Zurich, Switzerland.
J Prosthet Dent. 2008 Oct;100(4):264-73. doi: 10.1016/S0022-3913(08)60205-X.
The influence of different crown foundations on marginal seal and fracture resistance of ceramic crowns placed on endodontically treated teeth has not been clearly established.
The purpose of this study was to evaluate the marginal continuity and fracture behavior of high-strength all-ceramic crowns with different substructures in endodontically treated premolars.
Forty-eight human mandibular premolars were assigned to 6 groups, including a no-treatment group (UNTREATED) and a group for which the access cavity was restored with composite resin (Tetric Ceram) (COMP). In the remaining 4 groups, teeth were prepared to receive all-ceramic crowns with 0.8-mm-wide shoulders and axial dentin heights of 2 mm. No posts were used in the ENDOCROWN group. Glass fiber posts (FRC Postec) were used in group FRC-POST. Group ZRO-POST received zirconia ceramic posts (CosmoPost), and group GOLD-POST received cast gold posts (CM). Experimental lithia disilicate ceramic crowns were made and adhesively cemented (Variolink). All teeth were subjected to thermal cycling and mechanical loading (TCML) in a masticatory simulator (1,200,000 loads, 49 N, 1.7 Hz, 3000 temperature cycles of 5 degrees C-50 degrees C-5 degrees C). Marginal continuity was evaluated with scanning electron microscopy at x200. All specimens were loaded to failure in a universal testing machine at 0.5 mm/min after TCML. Data were analyzed using 1-way ANOVA and post hoc t tests with Bonferroni correction (alpha=.05).
Initially, mean values (SD) between 72.4 (15.8)% (ENDOCROWN) and 94.8 (3)% (FRC-POST) for continuous margins were found. With TCML, marginal continuity decreased significantly only in FRC-POST, to 75.5 (8.4)%, and in ENDOCROWN, to 44.7 (14.5)%. Mechanical load testing measured mean loads to failure between 1092.4 (307.8) N (FRC-POST) and 1253.7 (226.5) N (ZRO-POST) without significant differences between groups. Deep root fractures were observed in half of the specimens, irrespective of their groups.
Marginal continuity of the crowns studied was better and more stress resistant when posts and cores were included in the restoration of endodontically treated teeth with complete ceramic crowns. The placement of a post-and-core foundation did not influence the pattern of failure.
不同的冠部修复体对根管治疗后牙齿上所戴陶瓷冠的边缘封闭性和抗折性的影响尚未明确。
本研究的目的是评估根管治疗后的前磨牙中，具有不同内部结构的高强度全瓷冠的边缘连续性和断裂行为。
48颗人下颌前磨牙被分为6组，包括未治疗组（UNTREATED）和用复合树脂（Tetric Ceram）修复髓腔的组（COMP）。在其余4组中，牙齿被预备以容纳肩台宽度为0.8mm、轴向牙本质高度为2mm的全瓷冠。ENDOCROWN组未使用桩。FRC-POST组使用玻璃纤维桩（FRC Postec）。ZRO-POST组使用氧化锆陶瓷桩（CosmoPost），GOLD-POST组使用铸造金桩（CM）。制作实验性二硅酸锂陶瓷冠并用粘结剂粘结（Variolink）。所有牙齿在咀嚼模拟器中进行热循环和机械加载（TCML）（1200000次加载，49N，1.7Hz，3000个5℃-50℃-5℃的温度循环）。用扫描电子显微镜在200倍下评估边缘连续性。在TCML后，所有标本在万能试验机中以0.5mm/min的速度加载至破坏。数据采用单因素方差分析和经Bonferroni校正的事后t检验进行分析（α=0.05）。
最初，连续边缘的平均值（标准差）在ENDOCROWN组为72.4（15.8）%至FRC-POST组的94.8（3）%之间。经过TCML后，仅FRC-POST组的边缘连续性显著下降至75.5（8.4）%，ENDOCROWN组降至44.7（14.5）%。机械载荷测试测得的破坏平均载荷在FRC-POST组为1092.4（307.8）N至ZRO-POST组的1253.7（226.5）N之间，各组间无显著差异。无论所属组别，半数标本观察到深部牙根骨折。
在用全瓷冠修复根管治疗后的牙齿时，若修复体中包含桩核，则所研究冠的边缘连续性更好且更抗应力。桩核修复体的放置不影响破坏模式。
