## 1 Introduction
Binder jetting uses the extrusion of a bonding agent through a print head to a powder bed surface. Exposed particles connect through chemical reaction or solvent welding [31]. Selective Laser Sintering and Melting work with a laser to sinter or melt and then fuse powdered materials such as polymers, metal, ceramic or glass, which are applied layer-by-layer via rollers [30, 33]. The powder bed is preheated to lower the necessary energy input, and further hinders large thermal differences that can lead to part distortion [31]. Polymers in 3D-printing are composed of monomers, reactive diluents, cross linkers, initiators as well as pigments and fillers [30]. These components affect mechanical properties. [PERSON] et al. evaluated post-curing depth and homogenous cross-linking depending on varying pigmentation and different UV spectra [34]. Regarding the influence of pigmentation, it was concluded that black pigmentation negatively affected post-curing depth and homogenous cross-linking [34]. A larger wavelength (315-405 nm) resulted in deeper penetration and higher hardness [34]. Another study found that a divergence of the additives' and the resin's reflective index leads to scattering of the laser light resulting in reduced polymerization and inaccuracies [17]. Accuracy is an important factor to assess the usability of printed objects. Various studies investigated the effects of process parameters on three-dimensional accuracy. Parameters as building orientation, post-processing, platform position, layer thickness, laser power and post-curing time were mainly applied to embody the influence on accuracy [35, 22, 36]. [PERSON] et al. demonstrated that the layer thickness has major effect on accuracy compared to other parameters as laser power, over-cure and scanning distance [22]. Objects built with a low layer thickness and low laser power were the most accurate [22]. Regarding positioning of the 3D objects on the building platform, [PERSON] et al. evaluated that the objects arranged on the border of the building platform with a 45\({}^{\circ}\) angle resulted in minor deviations [37]. Other important factors influencing overall printing accuracy are polymerization shrinkage, separation stress, and optical image errors [35]. [PERSON] et al. compared the traction stress distribution of tilting and pulling-up separation at different separation speeds [36]. For both separation approaches, the stress increased with separation speed [36]. Moreover, the stress at the external position of the exposure area was greater than at the internal position [36]. Accuracy consists of trueness and precision [38; 39]. Trueness is defined as the closeness of agreement between measured test and true reference value [38; 39]. To evaluate trueness, deviations between the reference object and its produced replica are calculated [38; 39; 40]. Precision is determined as the closeness of agreement between the replicas, generated with the same device and method, to each other [38; 39]. Precision includes repeatability and reproducibility [38; 39]. The comparison of reference and test object can be executed by 3D surface comparisons or distance measurements [28]. To evaluate the accuracy of printed occlusal devices by superimposition, it is necessary to obtain digital datasets of the fabricated test objects. For digitalization, an industrial structured light scanner is used. High resolution scanners such as ATOS III Triple Scan have a reported trueness of 3 \(\upmu\)m and precision of 2 \(\upmu\)m [41]. The obtained standard tessellation language (stl) files of the test objects are superimposed with their reference object. As reference object, the virtual design data set of the printed occlusal devices is used. Reference and test objects are aligned via best-fit algorithm and point-to-surface measurements can be performed. Since the registration is performed in a three-dimensional coordinate system, the direction of deviation is demonstrated by negative and positive signs.