# Marginal Misfit Assessment in Common Restorative Materials for Cement‐Retained Fixed Implant Prostheses: An In Vitro Comparative Study

## TL;DR

This study compared how well different dental crown materials fit on implants with two types of connections, finding that veneered zirconia had the best fit.

## Contribution

The study introduces a direct comparison of marginal misfit in three restorative materials for cement-retained implant crowns under thermal cycling.

## Key findings

- Veneered zirconia restorations showed the lowest vertical marginal misfit.
- Internal and external connection types did not significantly affect misfit.
- All misfit values were below 50 µm, meeting clinical acceptance criteria.

## Abstract

To assess the vertical discrepancy at the abutment–crown interface (ACI) for cement‐retained crowns fabricated from three commonly used restorative materials across implants featuring external and internal connections.

A total of 30 implants with external (EC) and internal (IC) connections were included in this study. Each implant received a prefabricated titanium abutment, which was randomly attached using the torque recommended by the respective manufacturers. Three types of restorative materials—metal‐ceramic (MC), monolithic zirconia (MZ), and veneered zirconia (VZ)—were used to fabricate the crowns for each connection type and cemented to their respective abutments. Following 6000 cycles of thermal cycling between 5°C and 55°C, the vertical marginal misfit was evaluated using scanning electron microscopy. Data were statistically analyzed using repeated‐measures ANOVA, followed by Bonferroni post‐hoc test and paired t‐test.

The lowest marginal misfit was recorded for VZ restorations. Although the IC group showed lower mean misfit values compared to the EC group, this difference was not statistically significant (p = 0.980). Significant differences were found in the IC group between MZ and VZ (p = 0.016) and between MC and VZ (p = 0.035). Mean misfit values (µm) for each material were as follows: VZ = 18.7 (SD = 4.5), MZ = 42.2 (SD = 8.1), and MC = 39.9 (SD = 7.4).

Cement‐retained veneered zirconia restorations demonstrated less vertical ACI misfit compared to metal‐ceramic and monolithic zirconia restorations. The connection configuration did not influence the marginal misfit. All measured misfit values were below 50 µm.