Roughness and SEM Analysis of Manual and Ultrasonic Instrumentation over Different Crown Materials for Dental Implants Restorations

The use of new prosthetic materials makes it necessary to establish adequate hygienic protocols. It was decided to make prosthetic crowns from four different materials: composite, lithium disilicate, metal ceramic, and zirconium, and to evaluate the effects on the surfaces of four different instruments through SEM and roughness analysis: manual steel curette, manual titanium curette, ultrasonic steel insert, and ultrasonic peek insert. Forty crowns were made, ten of each type of material. For each material, five crowns were manually instrumented with steel inserts (curette 11-12, PDT, Missoula, USA) and titanium (Wingrove 3-4, PDT, Missoula, USA) on the lingual and buccal surfaces, respectively, and the other five crowns were instrumented with an ultrasonic peek insert (ICS-IC1, Mectron, Carasco, Italy) on the buccal surface and steel (PS, EMS, Nyon, Switzerland) on the lingual surface. At this point, surface roughness analysis was carried out. The data were analyzed with a Kolmogorov–Smirnov test. Therefore, it was decided to conduct two analyses with a Kruskal–Wallis test and Bonferroni post hoc test. Then, the instrumented crowns were analyzed by SEM. The analysis of the data shows that the highest average roughness was within the composite group, while the best material appeared to be disilicate. Significant differences existed between the groups, between the materials, and between the different instruments (p-value < 0.05). In the qualitative analysis carried out by SEM, the classic steel insert eliminated the residues of golden finishing. The peek insert created alterations on all tested surfaces. The steel curette did not create particular problems, with the exception of zirconium, where it was possible to observe some scratch lines. Instrumentation with the titanium curette created deeper incisions than the steel curette in the composite and disilicate. The best results came from the ultrasonic steel insert, while the best material appeared to be disilicate.