# Resin matrix ceramic crowns cemented on titanium bases: effect of surface treatments and stress distribution

## TL;DR

This study examines how different surface treatments affect the bonding and stress distribution of ceramic crowns on titanium bases used in dental implants.

## Contribution

The study introduces a comparison of resin nanoceramic and polymer-infiltrated ceramic network materials under various surface treatments for dental crowns.

## Key findings

- Surface treatments did not significantly affect the retention of crowns to titanium bases.
- Resin nanoceramic showed higher retention force and better stress distribution compared to polymer-infiltrated ceramic network.
- Most failures were cohesive within the material rather than at the interface.

## Abstract

Using Titanium bases (TBs) has shown excellent results in implant-supported rehabilitation. However, failures due to decementation can occur, and bonding success depends on the TB surface treatment. This study evaluated the effect of different TB surface treatments on the retention and failure mode of resin matrix ceramic (RMC) crowns after thermocycling and the stress distribution of RMC cemented on the TBs. 120 TBs were divided into eight groups (n = 15) according to the material (resin nanoceramic (RNC) and polymer-infiltrated ceramic network (PICN)) and the surface treatment of the TBs: no treatment (NT); Airborne-particle abrasion with 50μm aluminum oxide (Al2O3) (AL); Airborne-particle abrasion with 30μm silica-modified Al2O3 particles (SIAL30) and Airborne-particle abrasion with 110μm silica-modified Al2O3 particles (SIAL110). After thermocycling, retention, and failure modes were analyzed. Retention data underwent two-way ANOVA and Tukey Post Hoc test (α=0.05). Finite element analysis (FEA) assessed stress distribution according to maximum principal stress (σmax) on the crown and maximum shear stress (τmax) on the cement layer. No significant difference was observed among the surface treatments or their interaction with the material (p > 0.05). However, RNC presented higher retention force values for all surface treatments (p<0.001). FEA showed a higher σmax for PICN (317.31 MPa) than RNC (277.69 MPa), while τmax was higher for RNC (246.54MPa) compared to PICN (213.55MPa). Most failures were cohesive in the material. In conclusion, surface treatments did not influence the retention of crowns to TBs, with the RNC having higher retention and better stress distribution for the crown.