## 1 Introduction  
Three-dimensional printing is also called additive manufacturing or rapid prototyping, and it has contributed to the popularization of digital dentistry while overcoming the limitations of subtractive machining methods based on milling or grinding [1, 2]. The current methods of prosthesis production using 3D printing can overcome the limitations of subtractive manufacturing, such as reducing cutting forces due to the wear of milling tools, limitations associated with tool sizes, difficulty in manufacturing complex shapes, and material wastage. There are now wide ranges of equipment and raw materials with various prices and performances available in the market [3]. 3D printers based on stereolithography (SLA) or digital light processing (DLP) are currently the most widely used in digital dentistry. These two methods are classified based on the light source and curing method, and they have the advantages of high-precision printing and excellent surface texture [2; 4; 5]. The use of various photopolymeric resins makes it possible to manufacture diverse types of objects, from individual trays and dental models to final prostheses such as radiographic stents, provisional crowns, record bases, and dentures [1; 6; 7; 8; 9]. The development and use of 3D printers facilitate the fabrication of custom prostheses with complex configurations. However, the processing principles of 3D printers mean that certain specific factors that are not present in conventional manufacturing methods need to be considered. The accuracy and mechanical properties of 3D printing can be affected by variables such as machine settings, output position or build angle, number of layers, and configuration of the support structure. However, the high diversity of 3D printers and materials and the heterogeneity of their combinations mean that the 3D printing process and the associated postcuring process still need to be optimized and standardized [10; 11; 12; 13; 14]. Postcuring is an essential step when using a photopolymer resin with an SLA or DLP printer, as it can cause improvements in mechanical or biological properties through crosslinking of unreacted monomers after processing of 3D printing materials [15; 16]. Objects that have been printed by these printers are cleaned of unpolymerized residual monomers, and additional polymerization is performed using ultraviolet light (UV) produced by light-emitting diodes (LEDs) in postcuring equipment. The degree of polymerization greatly affects not only the biocompatibility and color stability of the fabricated object but also its mechanical properties and dimensional stability [14; 17; 18; 19]. It is known that the lower the polymerization rate in the 3D printing process, the greater the dimensional change occurs in the postcuring step, and the shrinkage of the area directly exposed to UV light occurs a lot, which can lead to bending due to non-uniform shrinkage [20]. Minimizing errors in the production process, and especially in the 3D printing process and postcuring, can result in a more predictable prosthesis manufacturing workflow. Several studies have investigated the precision, dimensional stability, and mechanical properties using several 3D printers [11; 12; 21; 22; 23; 24; 25; 26; 27]. Many companies provide guidelines for the use of materials and equipment required for the 3D printing process. However, in the process of manufacturing a series of prostheses using various products as an open system, it is often difficult to follow the guidelines of the company as it is. In addition, there are no unified guidelines among companies. Users are making the process based on empirical evidence. During the postcuring process, a dimensional change is expected because additional curing of the residual uncured resin occurs, but studies on this are lacking.