The purpose was to evaluate the degree of conversion (DC), internal adaptation (IA) and closed porosity (CP) of short-fiber reinforced resin composites (SFRC) associated with layered or bulk restorative procedures in deep MOD cavities. Eighty third molars with standardized MOD cavities (5-mm-depth, 2.5-mm-width) were randomly divided into four groups and restored as follows: 1) bulk SFRC; 2) layered SFRC; 3) flowable bulk-fill resin-based composites (RBC); 4) layered conventional RBC. After one-month wet storage the samples were subjected to micro-computed tomography measurements and scanning electron microscopy to assess the IA and CP. Micro-Raman spectroscopy was used to determine the DC in different depths. Data were subjected to ANOVA and Tukey’s post-hoc test, multivariate analysis and partial eta-squared statistics (p < 0.05). Pearson correlation coefficient was determined to assess the relationship among the parameters of interest. Gap/total interface volume ratio ranged between 0.22–0.47%. RBCs applied in bulk revealed significantly lower gap volume (p < 0.001) and CP (p < 0.05). Each group showed complete detachment on the pulpal and partial on the lateral walls, except for group3. While the highest DC% was achieved by the conventional RBC (87.2%), followed by the flowable bulk-fill (81.2%), SFRC provided the best bottom to top DC ratio (bulk: 96.4%, layered: 98.7%). The effect of factors studied (RBC type, filling technique) on IA and DC was significant (p < 0.001). Bulk placement of RBCs exhibited lower interfacial gap volume and achieved satisfactory DC without significant correlation between these parameters. Incremental insertion of SFRC had no advantage over bulk placement in terms of IA and DC.

中文翻译：

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深MOD腔体中散装或分层技术应用的短纤维增强树脂复合材料的内部适应性与转化程度之间的关系

目的是评估与深 MOD 腔中分层或整体修复程序相关的短纤维增强树脂复合材料 (SFRC) 的转化程度 (DC)、内部适应 (IA) 和闭孔率 (CP)。将 80 颗具有标准化 MOD 空腔（深度 5 mm，宽度 2.5 mm）的第三磨牙随机分为四组，并按如下方式修复：1）块状 SFRC； 2）层状钢纤维混凝土； 3）可流动的散装填充树脂基复合材料（RBC）； 4) 分层常规红细胞。湿储存一个月后，对样品进行微型计算机断层扫描测量和扫描电子显微镜以评估 IA 和 CP。显微拉曼光谱用于测定不同深度的DC。数据经过方差分析和 Tukey 事后检验、多变量分析和部分 eta 平方统计（p < 0.05）。确定皮尔逊相关系数以评估感兴趣的参数之间的关系。间隙/总界面体积比范围在 0.22-0.47% 之间。大量应用红细胞显示间隙体积 (p < 0.001) 和 CP (p < 0.05) 显着降低。除第3组外，各组均显示牙髓完全脱离，侧壁部分脱离。虽然传统 RBC 实现了最高的 DC%（87.2%），其次是可流动散装填充（81.2%），但 SFRC 提供了最佳的底部与顶部 DC 比率（散装：96.4%，分层：98.7%）。研究因素（红细胞类型、充盈技术）对 IA 和 DC 的影响显着 (p < 0.001)。红细胞的大量放置表现出较低的界面间隙体积并实现了令人满意的 DC，而这些参数之间没有显着相关性。就 IA 和 DC 而言，增量插入 SFRC 与批量放置相比没有优势。