Avaliação da interface de cimentação de laminados cerâmicos por meio da perfilometria e tomografia de coerência óptica

Abstract

Objective: Evaluate the interface of porcelain veneers bonded with different resin cements using profilometry and optical coherence tomography after thermal and erosive cycling. Materials and Methods: An in vitro laboratory experiment was conducted. Restorations were performed on IPS e.Max (Ivoclar-Vivadent) and bonded to 20 blocks of bovine enamel divided into two groups according to the bonding material: CR – Variolink Esthetic lC resin cement (Ivoclar Vivadent); RRA – Filtek Z 350 XT restoring resin (3M Espe) with controlled heating. The samples were submitted to thermal cycling (1000 cycles) with water at 5 and 55°C and erosive cycling with a gastric solution (pH 2.3) for 5 min three times per day for five days. Roughness and height difference between surfaces were measured using a 3D optical profilometer , CCI MP, England). The analysis of the enamel-ceramic interface and cement line was performed using the Callisto optical coherence tomography system (Thorlabs Inc, New Jersey, USA). Analyses were performed immediately after bonding (T0), thermal cycling (T1) and erosive cycling (T2). Results: Surface roughness tended to increase after thermal and erosive cycling, with significant roughness in the region of the enamel, resin and ceramic (p < 0.05). Significant differences were found between CR and RRA regarding the frequency of changes in the region of the cement line (p < 0.001). Adequate cement thickness was found in all CR specimens (n = 90; 100.0%) and inadequate cement thickness was found in all RRA specimens (n = 90; 100.0%). In the interface region, a significant difference in width was found between CR and RRA at both T0 (p = 0.002) and T2 (p = 0.022) and a significant difference in height was found between groups at T2 (p = 0.006). In the intragroup analysis, a significant increase in the size of the defects at the interface was found between T0 and T2. Significant differences were also found between CR and RRA regarding the frequency of changes in the interface region (p < 0.001). In CR, the majority of specimens had no alterations in the interface region at T0 (n = 31; 34.4%), whereas half of the samples had alterations at T2 (n = 45; 50.0%). In RRA, the majority of samples had some type of alteration at T0 (n = 49; 54.4%), mainly exposed cement. Conclusion: Defects at the interface were accentuated after the erosive challenge in both groups. The heated resin proved not to be adequate for bonding porcelain veneers. Optical coherence tomography is an excellent method for evaluating the interface of porcelain veneers.