One-year Clinical Evaluation of Zirconia-reinforced Lithium Silicate CAD/CAM Crowns

Objectives: Evaluate the clinical performance of chairside monolithic zirconia-reinforced lithium silicate (ZLS) CAD/CAM crowns.
Methods: One hundred ZLS CAD/CAM crowns (Celtra Duo, Dentsply/Sirona) were designed with CEREC Omnicam 4.3.1 and fabricated in an MCX milling unit (Dentsply/Sirona). All crowns were placed in one appointment by two experienced clinicians. Preparations followed standard guidelines for all-ceramic restorations with rounded shoulder margins, 1.5mm reduction over the central fissure, 2mm over cusps and 1.2mm axially. The crowns were divided into 2 groups of 50 restorations each. Group 1 crowns were oven-fired, glazed and cemented using self-etching, self-adhesive resin cement (Calibra Universal Cement/Dentsply Sirona). Group 2 crowns were hand polished with diamond impregnated spiral polishers (Meisinger) after milling and cemented using Prime & Bond Elect (Dentsply/Sirona) and dual cure resin cement (Calibra Ceram, Dentsply/Sirona).
Results: Tooth sensitivity was evaluated by report to cold stimulus. Mild sensitivity was reported up to 8-weeks for crowns cemented with self-etching, self-adhesive cement (Calibra Universal) and only up to 2-weeks for crowns cemented with Prime & Bond Elect and dual cure resin cement (Calibra Ceram). All crowns were evaluated by two independent examiners using modified USPHS rating at 6 months and 1 year. There was no difference in the gingival and plaque indexes between test and control teeth. The percent alpha scores were above 96% for color match at all recall intervals and above 98% for margin discoloration and absence of caries for both groups. Margins adaptation has become slightly detectable at 1-year compared to baseline with no reports of margin defects or crevice formation.
Conclusions: Chairside monolithic zirconia-reinforced lithium silicate (ZLS) CAD/CAM crowns performed well at 1 year. This study was supported by a grant from Dentsply/Sirona.