Abuabboud Osama, Marinescu Adrian-George, Paven Mihai, Kovacs Izabella-Maria, Nica Luminita Maria, Faur Andrei-Bogdan, Stoia Dan Ioan, Jivănescu Anca
Department of Restorative Dentistry and Endodontics, TADERP Research Center, Faculty of Dentistry, "Victor Babeș" University of Medicine and Pharmacy, 300041 Timișoara, Romania.
Department of Prosthodontics, TADERP Research Center, University of Medicine and Pharmacy "Victor Babeș", B-dul Revoluției 1989, No. 9, 300580 Timișoara, Romania.
Dent J (Basel). 2025 Jun 12;13(6):263. doi: 10.3390/dj13060263.
Endodontically treated molars are structurally weakened due to internal tissue loss, increasing their risk of fracture. Endocrowns, developed as a conservative alternative to post-core systems, have gained popularity with the rise of digital dentistry, CAD/CAM workflows, and 3D-printed restorations. In this context, the aim of the present pilot study was to investigate the influence of cement layer thickness, intracoronal depth, and dentine wall thickness on the fracture resistance of molars restored with 3D-printed endocrowns. Twelve extracted human molars were endodontically treated and restored with endocrowns fabricated from a 3D-printed resin material, SprintRay Crown (SprintRay Inc. Los Angeles, CA, USA), via masked stereolithography (MSLA) on a Prusa SL1 printer. Cementation was performed using RelyX Universal Resin Cement (3M, Maplewood, MN USA). Cone beam computed tomography (CBCT) was used to measure the dentine thickness and intracoronal depth before cementation and cement thickness after cementation. The fracture resistance was evaluated using a universal testing machine. For each variable (Td, Dp, Tc), the 12 specimens were divided into two groups ( = 6). Statistical analysis included Pearson correlation, a one-way ANOVA, and the non-parametric Mann-Whitney U test. Within the limitations of this pilot in vitro study, cement thickness demonstrated a strong positive correlation with fracture resistance (r = 0.577) and was the only variable showing statistical significance in the ANOVA (F = 7.847, = 0.019). In contrast, intracoronal depth and dentine wall thickness exhibited weaker and nonsignificant correlations. No significant mechanical advantage was observed from increasing the pulp chamber depth or peripheral dentine wall thickness. This result was further supported by nonparametric Mann-Whitney U testing ( = 0.015). : Cement layer thickness is a key biomechanical factor influencing the fracture resistance of endocrown restorations. Preparation depth and dentine wall geometry appear to have a less direct impact.
由于内部组织缺失，经牙髓治疗的磨牙结构会变弱，增加了骨折风险。作为桩核系统的一种保守替代方案而开发的全冠修复体，随着数字牙科、CAD/CAM工作流程和3D打印修复体的兴起而受到欢迎。在此背景下，本初步研究的目的是调查粘结剂层厚度、冠内深度和牙本质壁厚度对3D打印全冠修复磨牙抗折性的影响。选取12颗拔除的人磨牙进行牙髓治疗，然后用3D打印树脂材料SprintRay Crown（美国加利福尼亚州洛杉矶市SprintRay公司）在Prusa SL1打印机上通过掩膜立体光刻（MSLA）制作的全冠修复体进行修复。使用RelyX通用树脂粘结剂（美国明尼苏达州枫树wood市3M公司）进行粘结。在粘结前使用锥形束计算机断层扫描（CBCT）测量牙本质厚度和冠内深度，粘结后测量粘结剂厚度。使用万能试验机评估抗折性。对于每个变量（Td、Dp、Tc），将12个标本分为两组（每组 = 6）。统计分析包括Pearson相关性分析、单因素方差分析和非参数Mann-Whitney U检验。在本体外初步研究的局限性内，粘结剂厚度与抗折性呈强正相关（r = 0.577），并且是方差分析中唯一显示统计学意义的变量（F = 7.847，P = 0.019）。相比之下，冠内深度和牙本质壁厚度表现出较弱且无统计学意义的相关性。增加髓腔深度或周边牙本质壁厚度未观察到明显的机械优势。非参数Mann-Whitney U检验进一步支持了这一结果（P = 0.015）。结论：粘结剂层厚度是影响全冠修复体抗折性的关键生物力学因素。预备深度和牙本质壁几何形状似乎影响较小。
