A 3‐Year Split‐Mouth Randomized Non‐Inferiority Controlled Trial Comparing Cement‐Retained Monolithic <scp>CAD</scp> ‐ <scp>CAM</scp> Zirconia and Lithium Disilicate Crowns for Single Posterior Implant Restorations

ABSTRACT Objectives To evaluate whether monolithic CAD‐CAM lithium disilicate (LS 2 ) crowns are non‐inferior to monolithic CAD‐CAM zirconia (ZrO 2 ) crowns with respect to clinical and radiographic outcomes in single posterior implant restorations. Materials and Methods Patients with bilateral single‐tooth implants at homologous posterior sites were enrolled. Each implant was randomly assigned to receive either a monolithic CAD‐CAM ZrO 2 crown (Control) or a LS 2 crown (Test), both cemented onto customized titanium abutments. Marginal bone level change (ΔMBL) was the primary outcome. Non‐inferiority of LS 2 relative to ZrO 2 was evaluated using a prespecified margin of −0.5 mm for the paired difference in ΔMBL (LS 2 −ZrO 2 ). Implant and prosthesis survival, biological and technical complications, periodontal parameters, and FIPS were assessed as secondary outcomes. Results A total of 40 patients completed the 3‐year follow‐up. The survival rates were 97.5% for ZrO 2 and 100% for LS 2 , with one implant loss in the ZrO 2 group. Biological complication rates were 5% for ZrO 2 and 15% for LS 2 ( p = 0.219), while technical complication rates were 2.5% and 5% ( p = 1.000), respectively. No crown fractures, chipping, or debonding were found in either group. The ΔMBL was −0.62 ± 1.22 mm for ZrO 2 and −0.36 ± 1.07 mm for LS 2 . The paired mean difference in ΔMBL (LS 2 −ZrO 2 ) was 0.26 mm (95% CI: −0.17 to 0.70 mm). The lower confidence limit remained above the prespecified non‐inferiority margin of −0.5 mm, demonstrating non‐inferiority of LS 2 with respect to ΔMBL. No statistically significant differences were observed in mSBI, mPLI, or FIPS between the two groups ( p = 0.106, 0.201, 0.825). Conclusions Monolithic CAD‐CAM LS 2 crowns exhibit non‐inferior clinical and radiographic outcomes to ZrO 2 crowns over a 3‐year follow‐up period. Customized titanium abutments with cemented monolithic all‐ceramic crowns represent a reliable treatment option for single posterior implant‐supported restorations in the medium term. Trial Registration Chinese Clinical Trial Registry ( chictr.org.cn ): ChiCTR2200062023