Clinical Evaluation of CAD/CAM All-Ceramic Crowns: A Randomized Controlled Study Comparing Lithium Disilicate and...

To compare the marginal and internal adaptation and to evaluate the clinical performance and patient satisfaction of CAD/CAM-fabricated all-ceramic crowns produced from lithium disilicate (LDS) and lithium disilicate-reinforced lithium aluminosilicate (LAS) over a 24-month follow-up period.

This randomized controlled, single-blinded clinical trial included 59 posterior single crowns placed in 37 patients. Twenty-nine crowns were fabricated from LDS (IPS e.max CAD; Ivoclar Vivadent), and 30 crowns were fabricated from LAS (n!ce Blocks; Institut Straumann AG). Marginal and internal adaptation were assessed before cementation using an in vivo silicone replica technique. Clinical performance was evaluated at baseline and after 6, 12, and 24 months using the modified United States Public Health Service (USPHS) criteria together with the Gingival Index (GI), Plaque Index (PI), and patient satisfaction assessed using a visual analogue scale (VAS). Statistical analyses were performed at a significance level of p < 0.05.

No statistically significant differences were observed between the LDS and LAS groups regarding marginal, rounded shoulder, or occlusal gap measurements (p > 0.05). A statistically significant difference was observed at the axial measurement site (p = 0.014), with the LDS group exhibiting significantly greater axial internal gap values than the LAS group. During the 24-month follow-up period, six restorations failed because of fracture or debonding, including three LDS and three LAS crowns, resulting in survival rates of 89.7% for LDS, 90.0% for LAS, and 89.8% overall. Gingival and plaque index scores remained low and stable throughout the observation period, and patient satisfaction remained high in both groups, with no statistically significant differences between materials (p > 0.05). All clinically surviving restorations received Alpha or Bravo scores according to the modified USPHS criteria.

Within the limitations of this study, CAD/CAM-fabricated LDS and LAS crowns demonstrated comparable marginal adaptation, favorable clinical performance, and high patient satisfaction after 24 months of clinical service. The fully crystallized LAS ceramic appears to be a clinically acceptable and time-efficient alternative for posterior single-crown restorations. Nevertheless, long-term randomized clinical studies with larger sample sizes are required to confirm these findings.