Objective

The purpose of this systematic review was to summarize scientific evidence that evaluates in vitro fracture and fatigue strength of occlusal veneers in different thicknesses, CAD/CAM materials, and under different aging methodologies.

Materials and methods

An electronic search of 3 English databases (The National Library of Medicine (MEDLINE/PubMed), ScienceDirect, and EBSCOhost) was conducted. Laboratory studies published between September 2009 and October 2019 that evaluated fracture or fatigue strength of CAD/CAM occlusal veneers and used human teeth were selected. The included studies were individually evaluated for the risk of bias following a predetermined criterion. The outcomes assessed included the types of the restorative material, the thickness of the veneers, and aging methods.

Results

A total of 12 studies fulfilled the inclusion criteria. Most of the included studies (86%) evaluated the fracture strength of occlusal veneers. Two studies evaluated fatigue resistance. There was a significant relationship between the choice of materials and fracture strength. Polymeric materials performed better in fatigue testing in comparison to ceramics. Lithium silicate-based glass ceramics showed more favorable outcomes in a thickness of 0.7–1.0 mm. Fracture resistance values in all the included studies exceeded maximum bite forces in the posterior region.

Conclusions

The outcomes of this systematic review suggest that occlusal veneers can withstand bite forces in the posterior region, whereas the measurement of thickness should be standardized in order to have a fair comparison. Further research needs to be conducted to evaluate the longevity of this type of restorations clinically.

中文翻译：

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CAD/CAM 咬合贴面的抗断裂性：实验室研究的系统评价。

客观的

本系统评价的目的是总结评估不同厚度、CAD/CAM 材料和不同老化方法下咬合贴面体外断裂和疲劳强度的科学证据。

材料和方法

对 3 个英文数据库（国家医学图书馆 (MEDLINE/PubMed)、ScienceDirect 和 EBSCOhost）进行了电子搜索。选择了 2009 年 9 月至 2019 年 10 月发表的评估 CAD/CAM 咬合面和使用过的人类牙齿的断裂或疲劳强度的实验室研究。纳入的研究按照预先确定的标准单独评估偏倚风险。评估的结果包括修复材料的类型、贴面的厚度和老化方法。

结果

共有 12 项研究符合纳入标准。大多数纳入的研究（86%）评估了咬合贴面的断裂强度。两项研究评估了抗疲劳性。材料的选择与断裂强度之间存在显着关系。与陶瓷相比，聚合物材料在疲劳测试中的表现更好。硅酸锂基玻璃陶瓷在 0.7-1.0 mm 的厚度下表现出更有利的结果。在所有纳入的研究中，断裂阻力值都超过了后部区域的最大咬合力。

结论

该系统评价的结果表明，咬合贴面可以承受后牙区的咬合力，而厚度的测量应标准化，以便进行公平比较。需要进行进一步的研究以在临床上评估此类修复体的寿命。