Evaluation of Clinical Wear and Surface Roughness of Partial Restorations Produced by Additive and Subtractive Manufacturing Methods: A Split-Mouth Randomized Controlled Clinical Trial

The aim of this study is to compare the surface roughness and wear values of crowns fabricated using currently utilized 3D printing and CAD-CAM technologies. In recent years, crown restorations produced with CAD-CAM systems have been safely used in dentistry. These types of restorative materials are expected not to undergo significant wear themselves and also not to cause wear on natural teeth. Therefore, the structural resistance and hardness of the material are clinically very important. Restorations produced using 3D printing are among the latest technological developments in dentistry. Additive manufacturing has been defined by the American Society for Testing and Materials (ASTM) as "the process of joining materials layer upon layer to make objects from 3D model data, as opposed to subtractive manufacturing methodologies." 3D printers have started to be used in various disciplines of dentistry such as dental education, oral surgery, dental implantology, orthodontics, pedodontics, prosthodontics, and restorative dentistry. In restorative clinics, they can especially be used in intracoronal restorations. However, studies in this area are quite limited. The objective of this study is to evaluate the wear values using a Geomagic 3X device and the surface roughness values using a profilometer device over a 12-month period on single crown restorations applied to permanent first molars fabricated by CAD-CAM and 3D printing techniques. A total of 26 single crown restorations will be performed on first molars. Participants will be selected among individuals aged 18-50 who apply to the Department of Restorative Dentistry, Faculty of Dentistry, Çukurova University. Eligible individuals must be systemically healthy, have no periodontal attachment loss, have an indication for crown restoration, and have a natural opposing tooth in contact with the restored tooth.

In today's dentistry, where aesthetics has gained increasing importance, the use of CAD-CAM in the fabrication of fixed prostheses has become widespread. Although restorations produced by traditional methods are of high quality, they are mechanically and aesthetically affected due to being shaped manually by the dentist (conventional method). Therefore, errors that may occur during fabrication can negatively affect the durability and marginal adaptation of composite restorations. In a study comparing production techniques, composite crowns produced by the direct technique and single crown restorations fabricated using CAD-CAM were examined under an electron microscope. The composite restorations manufactured with the indirect technique showed more porosity, while no porosity was observed in restorations produced with the CAD-CAM method. This result may be attributed to the fact that the prefabricated CAD-CAM blocks are homogeneous and subjected to quality control during production. As a result, internal structural defects are generally not observed in milled products. The absence of porosity is an important factor in the durability and fit of restorations. 3D Printers Restorations produced using 3D printers are among the latest technological advancements in dentistry. Additive manufacturing has been defined by the American Society for Testing and Materials (ASTM) as "the process of joining materials layer upon layer to create objects from 3D model data, as opposed to subtractive manufacturing methodologies." 3D printers have begun to be used in various dental disciplines such as dental education, oral surgery, dental implantology, orthodontics, pedodontics, prosthodontics, and restorative dentistry. In restorative clinics, they can especially be utilized for intracoronal restorations. However, studies in this area remain quite limited. Null hypothesis of this study is that there is no statistically significant difference in clinical wear and surface roughness between single crown indirect restorations fabricated using additive and subtractive manufacturing methods.