Department of Operative and Esthetic Dentistry, Faculty of Dentistry, University of Szeged, Szeged, Hungary.
Department of Oral Surgery, Faculty of Dentistry University of Szeged, Szeged, Hungary.
J Prosthodont. 2019 Jan;28(1):e325-e331. doi: 10.1111/jopr.12777. Epub 2018 Mar 5.
Molar MOD (mesial-occlusal-distal) cavity preparation weakens relative cuspal stiffness by up to 63%, often resulting in cuspal fracture. This investigation inspects fracture resistance of MOD cavities restored using direct composite restoration.
120 extracted, intact mandibular molars were selected. MOD cavities with different depth/wall thickness were prepared in 9 groups (n = 12): A: 3 mm/3.5 mm, B: 3 mm/2.5 mm, C: 3 mm/1.5 mm, D: 5 mm/3.5 mm, E: 5 mm/2.5 mm, F: 5 mm/1.5 mm, G: 7 mm/3.5 mm, H: 7 mm/2.5 mm, I: 7 mm/1.5 mm. Specimens with 7 mm deep cavities received root canal treatment. The teeth were restored with dental composite. Maximal fracture strength test was conducted. Intact natural teeth were used as control. For statistical analysis Kruskal-Wallis ANOVA with post-hoc pairwise comparisons was used (α = 0.05).
Significant difference was indicated between the control and groups D, E, F, G, H, and I. No significant differences were found between the A, B, C groups and the control. Comparing the 5 and 7 mm cavity depth groups, there was no statistical difference between any of them.
Within the limitations of this investigation, the following conclusions can be drawn regarding molar teeth with a MOD cavity: 3 mm or shallower cavities can be restored to the physiological fracture strength with direct composite restorations; 5 mm or deeper cavities cannot be restored to the physiological fracture strength with direct composite restorations. Cusp thickness does not significantly influence fracture strength in molar MOD cavities with a direct composite restoration.
磨牙近中-牙合-远中（MOD）窝洞预备会使相对牙尖强度降低高达 63%，常导致牙尖折裂。本研究旨在检查使用直接复合树脂修复体修复 MOD 窝洞后的抗折裂能力。
选择 120 颗完整的下颌磨牙。在 9 组（每组 12 个）中制备不同深度/壁厚度的 MOD 窝洞：A：3mm/3.5mm，B：3mm/2.5mm，C：3mm/1.5mm，D：5mm/3.5mm，E：5mm/2.5mm，F：5mm/1.5mm，G：7mm/3.5mm，H：7mm/2.5mm，I：7mm/1.5mm。深度为 7mm 的窝洞进行根管治疗。用牙科复合树脂修复牙齿。进行最大断裂强度测试。将完整的天然牙齿用作对照。采用 Kruskal-Wallis ANOVA 进行统计分析，并进行事后两两比较（α=0.05）。
与对照组相比，D、E、F、G、H 和 I 组之间存在显著差异。A、B、C 组与对照组之间无显著差异。比较 5mm 和 7mm 窝洞深度组，它们之间没有统计学差异。
在本研究的限制范围内，可以得出以下结论：对于具有 MOD 窝洞的磨牙，3mm 或更浅的窝洞可以用直接复合树脂修复体恢复到生理断裂强度；5mm 或更深的窝洞不能用直接复合树脂修复体恢复到生理断裂强度。在使用直接复合树脂修复磨牙 MOD 窝洞时，牙尖厚度对牙尖抗折裂强度没有显著影响。
