With the development of ceramic materials for oral rehabilitation, it became possible to achieve satisfactory esthetic results not contemplated by metallic materials, particularly in the anterior region, because these ceramics allow a more remarkable similarity to the natural tooth [1], [2], [3]. However, ceramics, being a fragile material with low mechanical strength, makes it susceptible to cracks and fractures during its use [4], [5]. Consequently, it can lead to early replacement of the restored element due to the impairment of its clinical performance, which is one of the major concerns.

The correct selection of restorative materials is paramount to minimizing the wear of antagonistic dental structures. Materials for oral rehabilitation should be resistant to mechanical deformation, including attrition, as excessive wear of restorative material on occlusal surfaces may lead to a lack of contact concerning the antagonist and disturbances in the effectiveness of the masticatory system [6]. Thus, two aspects of interest should be considered for ceramic systems: resistance to abrasive wear of the material and predisposition of the material to generate wear on the antagonist surfaces of occlusion, whether in the natural or artificial dentition [7], [8]. One of the clinical concerns regarding ceramic materials is the wear that the ceramic material will cause on the antagonist structure. The wear behavior of ceramics is different from metal or composite resin. Ceramics and enamel are worn through a microfracture mechanism, whereas composite resins are worn by fatigue and abrasion [9], [10], [11].

Ideally, the wear resistance of restorative material and enamel should be similar, and the degree of vertical enamel wear occurring under normal conditions was estimated at 29 µm/yr for molar and 15 µm/yr for premolar [12]. This physiological wear of the oral cavity is accepted as a natural phenomenon. However, tooth wear can be accelerated by the materials used to restore an antagonist's tooth.

Dental wear can be defined as a consequence of a series of interrelated processes in which the material's surface is gradually corroded and removed [12], [13]. As reported by previous studies, wear occurs due to four main mechanisms: adhesive wear, abrasive wear, corrosive wear, and fatigue wear [12], [13]. In addition, other smaller types of wear are responsible for approximately 5% of the total wear observed. The degree of wear varies according to external factors such as masticatory force, types of food ingested, pattern of food intake, and location of the tooth and internal factors such as enamel thickness and hardness [13].

The complexity of the wear process and its difficult measurement in the oral environment makes it very difficult to conduct in vivo studies on tooth wear. However, to overcome the difficulties in in vivo methods, wear simulators and methods were developed to study the wear behavior of dental restorative materials in vitro [14], [15].

For the evaluation of tooth wear, several indirect techniques were developed and applied in previous studies as follows: gypsum replicas [16], scanning electron microscopy image analysis [17], computer graphics [18], three-dimensional (3D) scanners [19], and profilometry [20], [21]. However, according to previous studies with the methodologies already used, it has been stated that the replicas present disadvantages of inaccuracy and repositioning problems because the reproduction of the surfaces of teeth with prints before scanning adds a source of error [22]. Profileometer analysis can also produce over-contoured images when designing one's profile. Three-dimensional evaluation analyses are accurate, but the measurement accuracy of conical beam scanners approaches a few hundred microns; therefore, they have limited ability to determine tooth wear on occlusal surfaces. Moreover, due to the need to spray teeth with white powder, intraoral scanners can decrease measurement accuracy [23].

Therefore, considering the demand for oral rehabilitation using ceramic systems and taking into account the difficulties encountered in previous studies, a new methodology is proposed in the present study, using computerized microtomography and high-resolution and appropriate parameters in order to have more accurate results and compatible with clinical reality for the evaluation of dental wear. In this way, this in vitro study aimed to analyze the effect of different ceramic systems in the antagonist's tooth after cyclic loading by computerized microtomography. The null hypothesis is that antagonist's teeth do not affect different ceramic systems after cyclic loading.