Evaluation of zirconia and zirconia‐reinforced glass ceramic systems fabricated for minimal invasive preparations using a novel standardization method

Abstract

Objective: Currently, minimal invasive approaches combining less invasive finish line preparations and reduced ceramic thickness are required. The aim of this study was to evaluate the fracture resistance of two ceramic systems fabricated with two preparation designs using CAD/CAM standardization technology. Materials and methods: Forty intact human maxillary premolars were divided into two main groups according to the preparation technique. Group H (Horizontal): teeth with shoulder finish line and group V (Vertical): teeth with feather edge. Each main group was subdivided randomly into two subgroups according to the material used. Group CD (Celtra Duo) zirconia-reinforced glass ceramics and group K (KATANA) monolithic zirconia. CAD/CAM was used for standardization of natural teeth preparation. After cementation using self-adhesive resin cement, all specimens were subjected to 5000 thermal cycles and then were loaded until fracture. Failure types were evaluated using Stereomicroscopy and Scanning Electron Microscopy (SEM). Results: Nonsignificant; the higher mean value was recorded with VCD group (482.5 ± 103.8 N) and VK group (1347.6 ± 177.4 N) vs HCD group (471 ± 107.6 N) and HK group (1255.6 ± 121.3 N). SEM findings showed that fractures occurred mainly at the occlusal side of the crowns. Conclusions: Vertical preparation showed a promising alternative to horizontal preparation. Moreover, both Celtra Duo and KATANA crowns can be used in premolar area with 0.5 mm margin thickness. Clinical significance: Zirconia-reinforced glass ceramic and monolithic zirconia crowns may not necessitate the preparation of invasive finish lines as the type of finish line did not impair the strength after aging conditions

Influence of Hydrofluoric and Nitric Acid Pre-Treatment and Type of Adhesive Cement on Retention of Zirconia Crowns

“…Human teeth were utilized in the current study because of their bonding features, thermal characteristics, modulus of elasticity and strength that are closer to the clinical circumstances [44]. To prepare the teeth, the CAD-CAM technology has been used since it provides standard preparation of all teeth for in vitro tests and provides a reproducible tool that can be used in experiments to facilitate comparisons and minimize bias arising from differences in the processing of samples [45].…”

“…Each tooth was centrally mounted in acrylic resin block. To standardize the teeth preparation, the CAD-CAM technology was utilized [45]. A single tooth was prepared with aid of dental surveyor (Dentalfarm A3006 B manual surveyor, Turin, Italy).…”

Comparison of Mechanical Properties of Chairside CAD/CAM Restorations Fabricated Using a Standardization Method

“…A representative specimen was selected, and the fracture surface was observed at 25× magnification with an optical microscope (S39B, MICroscopes INC., St. Louis, MO, USA). Fracture patterns were analyzed by photographing the fracture surface with a camera connected to the microscope (Nikon C-DSD230, Nikon, Tokyo, Japan) [ 18 , 31 , 32 , 33 ].…”

“…Using a field emission scanning electron microscope (FE-SEM) (Sigma 300, ZEISS, Oberkochen, Germany), cracks were photographed and observed at a magnification that satisfactorily revealed their shapes from the lowest 21× magnification to the highest 336× magnification. By analyzing the images, detailed fracture patterns were observed and the causes of the fractures were identified [ 18 , 31 , 32 , 33 ].…”

“…CAD/CAM materials can also be used for implant restorations. As implant treatment is actively performed, studies on CAD/CAM restorations in implant abutments are also actively progressing [ 18 , 19 , 20 ]. However, research comparing it with natural teeth is insufficient.…”