31 August 2022

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Zirconia treatment for efficient cementation process

Massimo Gagliani

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Crown decementation are the most frequent failures in restorations using zirconia as an infrastructure. Increasing the roughness of the zirconia surface has been suggested to address this problem. 

The purpose of this systematic review and meta-analysis was to evaluate yttria-stabilized tetragonal zirconia polycrystal surface roughness produced with aluminum oxide airborne-particle abrasion and the erbium yttrium aluminum garnet (YAG), neodymium-doped YAG, or CO2 laser 

A huge number of papers has been analyzed according the standards of the systematic review and data were extracted from 17 studies.

Materials and methods
The first analysis of the subgroups was performed using the aluminum oxide airborne-particle abrasion and lasers.
The second analysis, methodologies were subgrouped into 4 modalities: 

- polished with silicon carbide abrasive papers in the presintered stage and airborne-particle abrasion with aluminum oxide after the sintering process 

- polished with silicon carbide abrasive papers in the presintered stage and airborne-particle abrasion with aluminum oxide after the sintering process

- polished with silicon carbide abrasive papers in the postsintered stage and airborne-particle abrasion with aluminum oxide after the sintering process

- no polish and airborne-particle abrasion with aluminum oxide after the sintering process. 

The roughness was higher in the experimental groups submitted to surface treatment and the group that used airborne-particle abrasion in the presintered stage presented an effect size of 2.71 as the value of greater surface roughness. 

Third analysis, the subgroups were examined according to the type of laser 

The effect size favored the Nd:YAG laser as the highest surface roughness value, 4.15, when compared with the Er:YAG laser, 0.60. 

Discussion
Techniques such as airborne-particle abrasion with aluminum oxide particles (Al2O3) were the most investigated surface treatment. In this systematic review,  94.7% of the airborne-particle abrasion was performed after the sintering process and only 5.3% before the sintering process. Airborne-particle abrasion with aluminum oxide before the sintering process was the most effective method because the presintered zirconia surface is softer. 

Conclusions
Airborne-particle abrasion with aluminum oxide on presintered zirconia is currently the most efficient methodology.
Irradiation with the Er:YAG, Nd:YAG, and CO2 la- sers was destructive due to the formation of a melted surface, large cracks, and a carbonized layer with silver pigments. 

Clinical Implications
Surface roughness is essential for the retention of dental restorations. These results provide a reference for the most researched and effective surface treatments.

For additional information: Evaluation of zirconia surface roughness after aluminum oxide airborne-particle abrasion and the erbium-YAG, neodymium-doped YAG, or CO2 lasers: A systematic review and meta-analysis