Faculdade São Leopoldo Mandic, Rua José Rocha Junqueira 13, Bairro Swift, Campinas, CEP: 13045-755, São Paulo, Brazil.
Piracicaba Dental School, University of Campinas, 901 Limeira Avenue, Areião, 13414-903, Piracicaba, São Paulo, Brazil.
J Mech Behav Biomed Mater. 2023 Aug;144:105961. doi: 10.1016/j.jmbbm.2023.105961. Epub 2023 Jun 12.
To evaluate the influence of the type of preparation and mechanical cycling on the fracture load and failure mode of semi-direct posterior resin composite restorations.
In total, 70 healthy third molars were used; 10 belonging to the control group (C - unprepared teeth) and 60 teeth prepared and restored with nanoparticle resin composite, divided into 3 groups (n = 20): O - exclusively occlusal preparation (Table Top); OV - occlusal preparation with buccal extension (Veneerlay); OVP - Occlusal preparation with chamfer on the proximal and buccal-lingual/palatal surfaces (Overlay). The preparations were performed with diamond burs with a thickness of 1 mm. The restorations were made with nanoparticulate resin composite (Filtek Z350 XT) and subsequently received additional polymerization (thermoprocessing). Cementation was performed with the use of universal adhesive system (Single Bond Universal) on dental substrate and dual resin cement (RelyX ARC). Half of the teeth in each group (n = 10) were submitted to mechanical cycling, simulating 6 months of clinical service (5 × 10 fatigue cycles), under dynamic loading of 130 N, at a frequency of 2Hz. Fracture load tests were performed in a universal testing machine with a 200 kgf load cell. Failure mode was classified using scores. Generalized linear models and Fisher Exact tests were applied to the data (significance level of 5%).
There were no significant differences between the types of preparation (p = 0.9435), or relative to cycling (p = 0.3764). The Fisher Exact Test showed a significant association between the groups and the type of failure (p = 0.0006), with preparations O (with cycling) and OVP (with and without cycling) exhibiting most failures with restoration fractures without involvement of the dental remnant.
Semi-direct restorations showed resistance to fracture load similar to that of healthy teeth and were capable of withstanding functional masticatory loads. The type of preparation influenced the failure mode of teeth. The Table Top and Overlay types of preparations were those had fewer catastrophic failures, suggesting that since they are more conservative preparations, they made it possible for the tooth to receive a new restorative procedure in the future in cases of failures.
评估预备类型和机械循环对半直接后牙树脂复合材料修复体断裂载荷和失效模式的影响。
共使用 70 颗健康的第三磨牙，其中 10 颗属于对照组（C-未预备牙齿），60 颗牙齿用纳米树脂复合材料预备和修复，分为 3 组（n=20）：O-仅进行牙合面预备（顶台型）；OV-颊面扩展牙合面预备（贴面型）；OVP-近中及颊舌/腭面预备成斜面（覆盖型）。使用厚度为 1mm 的钻石磨头进行预备。用纳米颗粒树脂复合材料（Filtek Z350 XT）制作修复体，然后进行额外的聚合（热加工）。在牙本质基底上使用通用粘结系统（Single Bond Universal）和双树脂粘结剂（RelyX ARC）进行粘结。每组中的一半牙齿（n=10）进行机械循环，在动态加载 130N、频率 2Hz 的条件下，模拟 6 个月的临床服务（5×10 疲劳循环）。在万能试验机上进行断裂载荷试验，使用 200kgf 传感器。使用分数对失效模式进行分类。对数据进行广义线性模型和 Fisher 精确检验（显著性水平为 5%）。
预备类型之间（p=0.9435）或相对循环（p=0.3764）无显著差异。Fisher 精确检验显示，组间和失效类型之间存在显著关联（p=0.0006），带循环的 O 型和不带循环的 OVP 型预备的修复体最容易发生无牙体组织参与的修复体断裂失效。
半直接修复体具有与健康牙齿相似的断裂载荷抵抗力，能够承受功能咀嚼负荷。预备类型影响牙齿的失效模式。顶台型和覆盖型预备的失败类型较少，表明由于它们是更保守的预备方式，在未来发生失败的情况下，为牙齿提供新的修复程序成为可能。
