Ten-year Clinical Evaluation of Lithium Disilicate Chairside CAD/CAM Crowns

Objectives: This longitudinal clinical trial studied the clinical performance of chairside CAD/CAM-generated lithium disilicate crowns (IPS e.MAX CAD; Ivoclar/Vivadent) for up to 10 years.
Methods: One clinician placed 100 CAD/CAM lithium disilicate crowns, each in one appointment. The preparation had shoulder margins with a rounded internal line angle, a minimum of 1.5 mm occlusal and 1.2 mm axial reduction. CEREC 3 (Dentsply Sirona) was used to fabricate the monolithic crowns. After milling, the crowns were fired under vacuum to complete the crystallization process; crowns were etched with 4.9% HF acid and silanated. The first 62 crowns (group 1 = 10 years) were cemented with either a self etching bonding agent and resin cement (ML=MultiLink-Automix; Ivoclar/Vivadent) or a self-adhesive resin cement (EC=Experimental Cement; Ivoclar/Vivadent). The remaining 38 crowns (group 2 = 7 years) were introduced later in the study and were cemented with a self-adhesive, light-cured resin cement (SP=SpeedCem; Ivoclar/Vivadent).
Results: Tooth sensitivity was evaluated by report to cold stimulus. Mild sensitivity was reported on 12% of the teeth at 2 weeks. All sensitivity resolved by 4 weeks. Two examiners evaluated the crowns using a modified USPHS rating. There was no difference in the gingival and plaque indexes between test and control teeth. The percent alpha scores were above 95% for color match and margin adaptation at all recall intervals. Five crowns debonded; 3 cemented with EC (13, 20, 36 months) and 2 with ML (36, 110 months). Two crowns presented with cusp fractures exposing dentin (75, 80 months). One crown had a root canal that failed at 86 months requiring extraction. One core/crown fractured from the tooth at 99 months.
Conclusions: The lithium disilicate crowns have performed very well for up to 10 years. This study was supported by a grant from Ivoclar Vivadent.