Tirone Federico, Salzano Stefano, Rolando Erik, Pirja Dan Andrei, Rodi Donata
Clinica Odontoiatrica Salzano Tirone, Cuneo, Italy.
Clinica Odontoiatrica Salzano Tirone, Cuneo, Italy.
J Dent. 2025 Sep;160:105851. doi: 10.1016/j.jdent.2025.105851. Epub 2025 May 24.
To evaluate the influence of different dimensional parameters on the incidence of framework fractures in a large sample of 151 implant-supported, screw-retained monolithic zirconia fixed complete dental prostheses (IFCDPs).
This retrospective observational study evaluated all patients rehabilitated with screw-retained zirconia IFCDPs at a private practice between October 2021 and May 2023. Inclusion criteria required a documented minimum follow-up period of 12 months after occlusal loading. Cantilever length (CL), distal cross-sectional connector area (CSCA), and screw access opening length (SAOL) were digitally measured on a computer-aided designed digital wax-up before framework milling. If the parameter ratios were below previously established cut-off values (CL/CSCA<0.51; CL/SAOL<1.48), the prostheses were produced; otherwise, the digital design was modified, and the ratios were recalculated. All prostheses were digitally produced using monolithic zirconia veneered on the gingival portion only. The primary outcome investigated was framework type II fractures (fractures of the distal cantilever).
A total of 151 prostheses delivered to 117 patients were analyzed. No type II fractures occurred. Two implants failed in two patients during the temporary phase, and two failed after delivery of the definitive prosthesis. Six prostheses failed (3.97 % prosthetic failure rate): one due to implant failure and five due to type I fractures (fractures occurring between, but not involving, the two most posterior SAOs). In one case, implant failure did not result in prosthetic failure.
In this study, no cantilever fractures were observed in patients restored with zirconia IFCDPs manufactured following specific parameters. Further studies are needed to confirm this positive outcome.
This study provides prosthetic dimensional parameters that may help prevent cantilever fractures in IFCDPs. In addition to CL, both CSCA and SAOL should be considered during framework digital design. In this study, no cantilever fractures were observed during the follow-up period when the cut-off values (CL/CSCA < 0.51; CL/SAOL < 1.48) were met.
在151例种植体支持的、螺丝固位的整体式氧化锆固定全口义齿（IFCDP）的大样本中，评估不同尺寸参数对支架骨折发生率的影响。
这项回顾性观察研究评估了2021年10月至2023年5月在一家私人诊所接受螺丝固位氧化锆IFCDP修复的所有患者。纳入标准要求在咬合加载后有记录的至少12个月随访期。在支架铣削前，在计算机辅助设计的数字蜡型上对悬臂长度（CL）、远端横截面连接体面积（CSCA）和螺丝通道开口长度（SAOL）进行数字化测量。如果参数比值低于先前确定的临界值（CL/CSCA<0.51；CL/SAOL<1.48），则制作义齿；否则，修改数字设计并重新计算比值。所有义齿均采用仅在牙龈部分 veneered 的整体式氧化锆数字化制作。研究的主要结局是支架II型骨折（远端悬臂骨折）。
共分析了交付给117例患者的151副义齿。未发生II型骨折。在临时阶段，两名患者的两颗种植体失败，在最终义齿交付后，又有两颗种植体失败。六副义齿失败（义齿失败率为3.97%）：一例因种植体失败，五例因I型骨折（发生在两个最后端SAO之间但不涉及它们的骨折）。在一例中，种植体失败未导致义齿失败。
在本研究中，按照特定参数制作的氧化锆IFCDP修复患者中未观察到悬臂骨折。需要进一步研究来证实这一积极结果。
本研究提供了可能有助于预防IFCDP悬臂骨折的修复尺寸参数。在支架数字设计过程中，除了CL之外，还应考虑CSCA和SAOL。在本研究中，当满足临界值（CL/CSCA<0.51；CL/SAOL<1.48）时，随访期间未观察到悬臂骨折。
