Effect of Tooth Abutment Height on Retention of CAD/CAM Monolithic Zirconia Crowns Cemented With Two Types of Cement: An In Vitro Study.

Statement of the Problem: Retention is still a primary concern in conservatively managing short clinical crowns (SCC) and minimal restorative space. In modern dentistry, there is a growing expectation for the durability and retention of indirect restorations, along with a high esthetic demand, even in unfavorable underlying conditions. Purpose: This study aims to establish a reliable approach for the conservative treatment of SCCs using monolithic zirconia crowns (MZC). Materials and Methods: Sixty human molars were collected and mounted in resin blocks. The teeth were prepared with two different abutment heights (2 and 4 mm). MZCs with buccal and lingual projections were designed and milled after digital scanning. Half of the restorations were cemented with TheraCem (TC) calcium silicate-based self-adhesive resin cement, while the remaining half were cemented with glass ionomer (GI) cement. The specimens underwent thermocycling and cyclic loading. A traction test was then performed in the universal testing machine to evaluate the debonding forces. Data was analyzed using Pearson correlation and one-way ANOVA tests. Results: A strong positive correlation was shown in Pearson analysis between the assigned group and the pull-out force ( Conclusions: We demonstrated the significant influence of TC cement on the pull-out force measurement, outperforming the GI cement. The abutment height also showed a smaller contribution to the force measurement. Low-thickness monolithic zirconia restorations cemented with self-adhesive resin cement can be recommended as a reliable and effective treatment option for clinicians managing cases with SCCs and compromised retention.