Universidade Federal de Uberlândia - UFU, School of Dentistry, Department of Operative Dentistry and Dental Materials, Uberlândia, MG, Brazil.
University of Manitoba, Faculty of Health Science, College of Dentistry, Department of Restorative Dentistry, Winnipeg, Canada.
Braz Oral Res. 2021 Dec 6;35:e119. doi: 10.1590/1807-3107bor-2021.vol35.0119. eCollection 2021.
To evaluate the effect of selective or nonselective carious tissue removal and the use of a resin-modified glass ionomer (RMGIC) liner under bulk fill resin composite restoration on the stress at the pulp chamber, the elastic moduli of hard, firm, soft and intact dentin were calculated using nanoindentation. Post-gel shrinkage of the bulk fill resin composite and RMGIC were determined using the strain-gauge method. Six finite element models were created by using digital radiography with the combination of two study factors: a) carious tissue removal: selective removal or nonselective removal of carious tissue, and b) use of RMGIC liner: with or without 1.0 mm of RMGIC liner. The modified von Mises stresses (mvm) (MPa) were extracted on the nodes of the internal wall of the pulp ceiling chamber at 100 N occlusal loading. Data were analyzed descriptively and recorded quantitively. Both study factors influenced the stress distribution. The mvm stress during the restorative procedure was higher for nonselective carious tissue removal without RMGIC (25.9 MPa) and lower for selective carious tissue removal associated with RMGIC (13.5 MPa). The dentin elastic modulus increased from soft carious (3.6 ± 0.3 MPa) to firm carious (5.2 ± 1.0 MPa) to hard carious (10.9 ± 1.2 MPa) to intact dentin (22.7 ± 3.0 MPa). Molars with carious lesions showed high mvm stress at the pulp ceiling (89.6 MPa) and at fragilized coronal structure remaining. Selective carious tissue removal followed by restoration using a Vitrebond liner and Tetric N-Ceram Bulk fill reduced the stress at the pulp chamber ceiling.
为了评估在大量填充树脂复合材料修复中选择性或非选择性龋组织去除以及使用树脂改性玻璃离子（RMGIC）衬垫对牙髓腔应力的影响，使用纳米压痕法计算了硬、固、软和完整牙本质的弹性模量。使用应变计法测定了大量填充树脂复合材料和 RMGIC 的凝胶后收缩。通过数字射线照相术结合两个研究因素创建了六个有限元模型：a）龋组织去除：选择性去除或非选择性去除龋组织，b）使用 RMGIC 衬垫：使用或不使用 1.0 毫米的 RMGIC 衬垫。在 100 N 咬合载荷下，从牙髓顶腔内壁的节点提取修正后的 von Mises 应力（mvm）（MPa）。对数据进行描述性分析并进行定量记录。两个研究因素都影响了应力分布。在没有 RMGIC 的非选择性龋组织去除和非选择性龋组织去除而不使用 RMGIC 的情况下，修复过程中的 mvm 应力更高（25.9 MPa），而选择性龋组织去除并使用 RMGIC 时，mvm 应力更低（13.5 MPa）。牙本质弹性模量从软龋（3.6 ± 0.3 MPa）增加到硬龋（5.2 ± 1.0 MPa）再到硬龋（10.9 ± 1.2 MPa）到完整牙本质（22.7 ± 3.0 MPa）。有龋损的磨牙在牙髓顶（89.6 MPa）和剩余的脆弱冠部结构处显示出高 mvm 应力。选择性龋组织去除后，使用 Vitrebond 衬垫和 Tetric N-Ceram 大量填充修复可降低牙髓腔顶的应力。
