645 Clinical Evaluation of Lithium Disilicate Chair-side CAD/CAM Crowns at 4-years

Friday, March 23, 2012: 8 a.m. - 9:30 a.m.
Presentation Type: Oral Session
D. FASBINDER, Dept. of Cariol & Rest. Sci. & Endo, University of Michigan, Ann Arbor, MI, J. DENNISON, Cariology ,Restorative Sciences and Endodontics, University of Michigan, Ann Arbor, MI, D. HEYS, University of Michigan, Ann Arbor, MI, and G.F. NEIVA, Cariology, Restorative Sciences and Endodontics, University of Michigan, Ann Arbor, MI
Objective: This longitudinal trial studied the clinical performance of a lithium disilicate ceramic material (IPS e.MAX CAD; Ivoclar Vivadent) for chair-side CAD/CAM-generated crowns.

Methods: One clinician placed 100 CAD/CAM lithium disilicate crowns. The preparation had shoulder margins with a rounded internal line angle and a minimum of 1.5 mm occlusal and 1.2 mm axial reduction.  A CEREC 3 unit (Sirona Dental) 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 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 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 15% of the teeth at 1 week. All sensitivity resolved by 4 weeks. The crowns were evaluated by two examiners 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 at all recall intervals and remained at 100% for margin adaptation, caries, and crown fracture for both groups after four years. Percent alpha scores for margin discoloration at four years were 70% (ML) and 82% (EC) and remained at 100% for SP after one year.  No surface chipping has been identified on any of the crowns. Two crowns cemented with EC debonded at 13 and 20 months, respectively.

Conclusions: The lithium disilicate crowns have performed well at 4 years. This study was supported by a grant from Ivoclar Vivadent.

This abstract is based on research that was funded entirely or partially by an outside source: Grant by Ivoclar Vivadent

Keywords: Adhesion, CAD/CAM, Ceramics and Clinical trials