Objective: To evaluate coating materials regarding color and roughness changes when applied over a composite resin.

This study investigated the effect of irradiation with an erbium‐doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty‐three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80 mJ/2 Hz) with pulse widths of 50 μs (ii), 100 μs (iii), 300 μs (iv), or 600 μs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (μSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica‐coated groups. Regarding μSBS, after aging, specimens from all experimental groups presented very low and similar μSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6 MPa), while coating partially sintered specimens with silica resulted a BFS (826.9 ± 60.9 MPa) similar to that of the untreated control group (794.9 ± 101.7 MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300 μs pulse width, specimens exhibited the lowest BFS value (514.1 ± 71.5 MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented.

Objectives To evaluate the effect of atmospheric pressure plasma (PLA), sandblasting (SAN), silanization (SIL) and hydrophobic bonding resin (HBR) on the micro‐shear bond strength (MSBS) of fresh nanofilled (NF) or microhybrid (MH) composites to water‐aged nanofilled composite. Materials and methods NF plates were fabricated and stored in distilled water for 4 months. The aged plates were assigned to the groups (n = 6): 1‐ untreated; 2‐ SAN + SIL + HBR; 3‐ HBR; 4‐ PLA + HBR; 5‐ SAN + HBR; 6‐ SAN + PLA + HBR; and 7‐ PLA. Two fresh composite cylinders were constructed on each plate with NF or MH composites and tested after 24 h or 1 year of water‐storage, using the MSBS testing. Data were analyzed by three‐way ANOVA and Tukey test (α = 0.05). Results NF yielded better outcomes than MH at 24 h, which was not observed at 1 year. HBR showed the highest MSBS results, while untreated and PLA groups yielded the lowest one. MSBS reduced for all groups after 1 year. Conclusions Only HBR can obtain good MSBS results, while PLA alone was not beneficial. After 1 year, a reduction in repair MSBS was observed and the type of composite did not influence the results. Clinical relevance The repair technique can be simplified with the use of only an adhesive and macromechanical retentions in the old composite, regardless the type of fresh composite.

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SUMMARY Objectives To evaluate the effect of argon plasma treatment (PLA) when combined with sandblasting (SAN), silanization (SIL), and hydrophobic bonding resin (HBR) on the shear bond strength (SBS) of a two-year water-aged resin composite bonded to a newly placed composite after 24 hours and one year of water-storage. Methods and Materials Thirty-six light-cured composite plates (20mm x 20mm x 4mm thick) were obtained and stored at 37°C in distilled water for 2 years. These aged plates were distributed into 6 groups (n=6) according to the surface treatment: no treatment (Negative Control); SAN+SIL+HBR (Positive Control); SAN+PLA+SIL+HBR; PLA+ SIL+HBR; PLA+SIL; PLA+HBR. Fresh resin composite cylinders were built up using silicone molds (hole: 1.5 mm high x 1.5 mm diameter) positioned over the aged plates. Half of the SBS samples were stored in distilled water for 24 hours and loaded until failure, while the other half were stored for 1 year before being tested. Data were submitted to two-way analysis of variance and post-hoc Tukey Test (preset alpha of 0.05). Results Positive Control, SAN+PLA+SIL+HBR and PLA+SIL+HBR groups presented higher SBS means at the 24 hour evaluation. After 1 year of water storage, all groups demonstrated significant SBS reduction, with the SAN+PLA+SIL+HBR group presenting the highest SBS. Conclusions Resin plasma treatment in combination with other surface treatments can improve the SBS of composite repairs after one year of water storage. The SBS of the composite repair was not stable over time regardless of the surface treatment.

Purpose: This study aims to evaluate the effect of erosive, abrasive, and erosive/ abrasive challenges on the glaze layer of ceramic materials. Methods: Ninety-five samples of monolithic zirconia (MZ) (LuxaCam Zircon HT-Plus) and lithium disilicate (LD) (IPS e.max CAD) were divided according to the response variables: Surface roughness and surface loss (n = 10), evaluated with optical profilometry; surface topography, with scanning electron microscopy SEM (n = 3); and biofilm deposition, with microbiological assay (n = 5). The evaluations were performed in three different time evaluations: (a) Sintered, (b) Glaze, and (c) Challenge (Erosion, Abrasion, and Erosion/Abrasion). Erosion consisted in immersing specimens in HCl solution, abrasion was performed with brushing machine, and erosion/abrasion consisted of a combination of the two previous protocols. Data were analyzed with parametric tests (P < 0.05). Results: MZ glaze layer presented significantly higher surface roughness (P = 0.00), surface loss (P = 0.03), and biofilm deposition (P = 0.00) than LD. Abrasion and erosion/abrasion showed similar outcomes, generating significantly higher surface roughness (P = 0.00), surface loss (P = 0.00), and biofilm deposition (P = 0.01) than erosion. Conclusions: Glaze layer properties were altered by the challenges, with abrasion and erosion/abrasion generating higher surface roughness, surface loss, and biofilm deposition than erosion. A significant correlation was found between the surface roughness and biofilm deposition. Clinical significance: The glaze layer is susceptible to challenges, especially to abrasion and erosion/abrasion, which generated greater surface roughness and surface loss than erosion. The greater surface roughness lead to a greater biofilm deposition on the glaze layer.

Agradeço à minha orientadora, Professora Dra. Adriana Bona Matos, por toda a força que estimulou em mim. Por me ensinar o que é uma pós-graduação e me dar todo o suporte e a liberdade para me desenvolver de forma plena neste meio. Por me incentivar sempre a ser determinada, focada e dedicada. Foi um período de extremo aprendizado, de crescimento pessoal e profissional, e ele só foi possível porque tive uma inspiração para me guiar. Ao meu amigo e irmão de coração, Matheus Kury Rodrigues, por dividir este e todos os outros momentos da minha vida com tanta entrega e cumplicidade. Muito antes de tudo começar, já sonhávamos este momento juntos e, agora que alcançamos, são nossos sonhos compartilhados que me estimulam a seguir em frente. Sou uma pessoa melhor, uma amiga melhor e uma profissional melhor por te ter do meu lado. Te amo com todo meu coração. À minha família paulistana: todos os meus queridos amigos que o mestrado me proporcionou conhecer. Essa mistura linda, que traz o Brasil para dentro do departamento da Dentística todos os dias, com diferentes realidades, culturas, histórias e sotaques. Obrigada pela companhia e amizade que tornaram todos os dias mais leves. Obrigada por todo o apoio, por toda a ajuda, por toda a troca, por toda a entrega. Foram dois anos lindos e especiais na minha vida graças ao convívio com vocês, meus amigos forasteiros.

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