Comparative evaluation of the fracture resistance of pediatric zirconium crowns manufactured by CAD/CAM with prefabricated zirconium crowns: in vitro study

A full coronal restoration is often recommended in the treatment of primary teeth that have undergone pulpal treatment, have been traumatized, or have extensive carious lesions. Today, with the development of aesthetic dentistry, the increase in cosmetic expectations in children has brought the use of prefabricated zirconium crowns with aesthetic properties similar to natural tooth structure in primary teeth. Although prefabricated zirconium crowns are aesthetic, robust and functional crowns; It has disadvantages such as not being compatible, requiring more preparation and not having personalized crowns. In recent years, crowns produced with the CAD/CAM system in dentistry have started to become popular. With these systems, aesthetically and functionally satisfactory personalized crowns with low fracture rates and long clinical lifetimes can be produced in a single appointment. In this study, it was aimed to evaluate the fracture resistances of pediatric zirconium crowns produced with CAD/CAM cemented with a thermal cycle chewing simulator and two different luting cements aged with saliva, in comparison with prefabricated zirconium crowns. According to the type of crown, 120 epoxy resin samples used in the study; It is divided into two groups: zirconium crowns produced with CAD/CAM (Liaoning Upcera Co. Ltd. China) and prefabricated zirconium crowns (NuSmile, Houston, Texas, USA) (n=60). The samples were further divided into two subgroups using resin modified glass ionomer cement (GC FujiCEM Evolve, Tokyo, Japan) and bioactive glass cement (Activa Bioactive Cement, Watertown, MA. America) and cemented according to the manufacturer's instructions (n=30). Afterwards, the fracture resistance data obtained from the Universal test device of the samples, which were subjected to two different aging procedures, namely the chewing simulator with thermal cycle and saliva, were evaluated statistically. The highest mean fracture resistance values among all groups were obtained from the group in which the zirconium crowns produced with CAD/CAM were cemented with resin modified glass ionomer cement and aged with saliva. The lowest average fracture resistance values were obtained from the group in which the zirconium crowns produced with CAD/CAM were cemented with bioactive glass cement and aged with a thermal cycle chewing simulator. Although there was a statistically significant difference between the fracture resistance values according to the crown type, it was observed that the fracture resistance values of the zirconium crowns produced with CAD/CAM were higher than the prefabricated zirconium crowns (p=0.000). As a result, it is seen that zirconium crowns produced with CAD/CAM and prefabricated zirconium crowns are a promising alternative, especially in the restoration of primary teeth with polyhedral caries lesions, due to their existing advantages and sufficient fracture resistance values. In addition to parameters such as fracture resistance, pediatric dentists in clinical practice; Crown selection should be made by taking into account factors such as aesthetic expectation, oral hygiene, patient cooperation, individuality of the crown and cost.