Effect of deproteinization and tubular occlusion on microtensile bond strength and marginal microleakage of resin composite restorations

Dentin adhesion procedure presents limitations, especially regarding to lifetime stability of formed hybrid layer. Alternative procedures have been studied in order to improve adhesion to dentin. OBJECTIVE: The aim of this study was to evaluate in vitro the influence of deproteinization or dentin tubular occlusion, as well as the combination of both techniques, on microtensile bond strength (µTBS) and marginal microleakage of composite resin restorations. MATERIAL AND METHODS: Extracted erupted human third molars were randomly divided into 4 groups. Dentin surfaces were treated with one of the following procedures: (A) 35% phosphoric acid gel (PA) + adhesive system (AS); (B) PA + 10% NaOCl + AS; (C) PA + oxalate + AS and (D) PA + oxalate + 10% NaOCl + AS. Bond strength data were analyzed statistically by two-way ANOVA and Tukey's test. The microleakage scores were analyzed using Kruskal-Wallis and Mann-Whitney non-parametric tests. Significance level was set at 0.05 for all analyses. RESULTS: µTBS data presented statistically lower values for groups D and B, ranking data as A>C>B>D. The use of oxalic acid resulted in microleakage reduction along the tooth/restoration interface, being significant when used alone. On the other hand, the use of 10% NaOCl alone or in combination with oxalic acid, resulted in increased microleakage. CONCLUSIONS: Dentin deproteinization with 10% NaOCl or in combination with oxalate significantly compromised both the adhesive bond strength and the microleakage at interface. Tubular occlusion prior to adhesive system application seems to be a useful technique to reduce marginal microleakage

Clinical strategies for esthetic excellence in anterior tooth restorations: understanding color and composite resin selection

Direct composite resin restorations have become a viable alternative for patients that require anterior restorative procedures to be integrated to the other teeth that compose the smile, especially for presenting satisfactory esthetic results and minimum wear of the dental structure. Technological evolution along with a better understanding of the behavior of dental tissues to light incidence has allowed the development of new composite resins with better mechanical and optical properties, making possible a more artistic approach for anterior restorations. The combination of the increasing demand of patients for esthetics and the capacity to preserve the dental structure resulted in the development of different incremental techniques for restoring fractured anterior teeth in a natural way. In order to achieve esthetic excellence, dentists should understand and apply artistic and scientific principles when choosing color of restorative materials, as well as during the insertion of the composite resin. The discussion of these strategies will be divided into two papers. In this paper, the criteria for color and material selection to obtain a natural reproduction of the lost dental structures and an imperceptible restoration will be addressed

Estudo in vitro da resistência à fratura de raízes debilitadas. Efeito de diferentes tratamentos restauradores

A preservação e a restauração de dentes despolpados severamente debilitados é um procedimento complexo e relativamente imprevisível. Este estudo avaliou a resistência à fratura de raízes bovinas experimentalmente debilitadas, reconstruídas internamente com diferentes materiais restauradores em combinação com pinos pré-fabricados de fibra de vidro comparados com raízes íntegras restauradas com núcleo metálico fundido ou pino de fibra de vidro. Foram selecionadas raízes de 120 (n=15) incisivos bovinos inferiores de dimensões semelhantes, dos quais, 90 foram internamente preparados para simular uma raiz debilitada. Todas as raízes foram preenchidas com diferentes materiais restauradores e os espécimes foram submetidos ao teste de resistência ao fracasso/ fratura com a aplicação de uma carga compressiva tangencial a um ângulo de 135º em relação ao longo eixo axial das raízes. Resultados indicaram diferenças estatisticamente significante entre os grupos. As raízes debilitadas restauradas com núcleo metálico fundido (grupo NMF-RD) demonstraram os mais baixos valores de resistência à fratura (107.7436 N), sendo estatisticamente diferentes dos demais grupos. As raízes íntegras restauradas com núcleo metálico fundido (NMF-RI) mostraram os maiores valores de resistência (362.3308 N), mas com diferenças estatisticamente significantes somente quando comparadas às raízes debilitadas restauradas com cimento resinoso dual (Variolink II, Ivoclar Vivadent - grupo Vario-RD), cimento resinoso autopolimerizável (Multilink, Ivoclar Vivadent - grupo Multi-RD) e cimento de ionômero de vidro modificado por resina (Vitremer, 3M ESPE - grupo Vitre-RD) associado com pino de fibra de vidro...The preservation and restoration of severely weakened pulpless teeth is a difficult and relatively unpredictable procedure. This study evaluated the resistance to fracture of experimentally weakened bovine roots internally reconstructed with different filling materials in combination with prefabricated fiberglass posts compared with restored roots that were relatively intact. The roots of 120 mandibular bovine incisors with similar bulks were selected. Of these, 90 were internally prepared to standardized dimensions, thereby simulating weakness. All roots were filled with different restorative materials. The specimens were submitted to the fracture resistance testing with the application of a tangential compressive loading at an angle of 135º in relation to the long axes of the roots. Results indicated statistically significant differences among the groups. The weakened roots restored with the cast post-core (group NMF-RD) demonstrated the lowest fracture resistance values (107.7436 N), which were significantly different from the averages of the remaining groups. The healthy roots restored with the cast post-core (group NMF-RI) showed the highest values (362.3308 N), but statistically significant differences were observed only when compared with weakened roots restored by the dual-cured resin cements (Variolink II, Ivoclar Vivadent - group Vario-RD), chemically cured resin cements (Multilink, Ivoclar Vivadent - group Multi-RD) and resin-modified glass-ionomer cement (Vitremer, 3M ESPE - group Vitre-RD) associated with fiberglass posts. There was not statistically significant differences among the groups of the weakened roots restored with self-adhesive universal resin cement (RelyX Unicem, 3M ESPE - group Unicem-RD), composite resin (Tetric 15 Ceram, Ivoclar Vivadent - group Tetric-RD), group Vitre-RD and group Vario-RD... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Avaliação da influência da solução de irrigação na resistência adesiva de um cimento resinoso

INTRODUÇÃO: A contaminação do substrato dentinário pode interferir na qualidade de união entre materiais adesivos e o dente. OBJETIVO: Investigar a influência de diferentes soluções de irrigação na resistência de união de um cimento resinoso. MATERIAL E MÉTODO: Foram selecionadas 40 coroas dentais bovinas, divididas em quatro grupos: G0 = soro; G1 = clorexidina; G2 = EDTA; G3 = clorexidina 0,12%, após condicionamento ácido. Em seguida, foram confeccionados cilindros de cimento resinoso utilizando-se uma matriz de Tygon com diâmetro interno de 1 mm e 2 mm de altura. A fotoativação foi realizada por aparelho de luz LED com 900 mW/cm² por 40 segundos. Foram confeccionados quatro cilindros de cimento resinoso para cada coroa bovina, totalizando 40 corpos de prova de cimento resinoso para cada grupo avaliado. O teste de resistência adesiva por microcisalhamento foi realizado após 24 horas. Decorrido esse período, os cilindros de cimento resinoso foram testados em uma máquina universal de ensaios (EMIC). Os dados obtidos foram submetidos à análise estatística pelos testes ANOVA e Tukey (p = 0,001). RESULTADO: Não houve diferenças estatisticamente significativas entre os grupos estudados, com exceção para o G3, que apresentou de forma significativa os menores valores de resistência adesiva. CONCLUSÃO: As diferentes soluções irrigadoras utilizadas previamente ao condicionamento ácido na dentina não interferem na resistência de união por microcisalhamento

Effect of finishing and polishing techniques on the surface roughness of a nanoparticle composite resin

Aim: To evaluate the surface roughness of the resin Filtek Z350 (3M ESPE) after different finishing and polishing techniques. Methods: Sixty specimens of 7x2 mm were made and distributed in 6 groups (n=10), according to the technique employed: G1 (control) – polyester strip – no finishing or polishing; G2- multi-blade burs; G3- diamond burs 3195F and 3195FF; G4- Diamond Pro Discs (FGM); G5- Sof-Lex Discs (3M ESPE); G6- Robinson bristle brushes with pumice paste for 20 s and felt disc with 2-4 μm diamond paste for 30 s. The specimens were stored in artificial saliva at 37°C for 7 days. After the finishing and polishing techniques, surface roughness (Ra, μm) was measured using Surf-Corder profilometer SE 1700. Data were subjected to one-way ANOVA and Tukey’s test at 5% significance level. Results: G3 presented the highest surface roughness mean value (0.61). G5 presented the lowest surface roughness mean value (0.15), but it was not significantly different from G1, G4 and G6. Conclusions: According to the obtained results, Z350 composite resin presented the lowest surface roughness when finishing and polishing systems were used (Sof-lex and Diamond Pro discs and Robinson bristle brush with pumice plus Diamond® felt disc with Diamond Excel® paste). The use of diamond burs (G3) resulted in the highest composite surface roughness. There was no significantly different between G1, G4, G5 and G6

Effect of finishing and polishing techniques on the surface roughness of a nanoparticle composite resin

evaluate the surface roughness of the resin Filtek Z350 (3M ESPE) after different finishing and polishing techniques. Methods: Sixty specimens of 7x2 mm were made and distributed in 6 groups (n=10), according to the technique employed: G1 (control) polyester strip no finishing or polishing; G2- multi-blade burs; G3- diamond burs 3195F and 3195FF; G4- Diamond Pro Discs (FGM); G5- Sof-Lex Discs (3M ESPE); G6- Robinson bristle brushes with pumice paste for 20 s and felt disc with 2-4 μm diamond paste for 30 s. The specimens were stored in artificial saliva at 37°C for 7 days. After the finishing and polishing techniques, surface roughness (Ra, μm) was measured using Surf-Corder profilometer SE 1700. Data were subjected to one-way ANOVA and Tukeys test at 5% significance level. Results: G3 presented the highest surface roughness mean value (0.61). G5 presented the lowest surface roughness mean value (0.15), but it was not significantly different from G1, G4 and G6. Conclusions: According to the obtained results, Z350 composite resin presented the lowest surface roughness when finishing and polishing systems were used (Sof-lex and Diamond Pro discs and Robinson bristle brush with pumice plus Diamond® felt disc with Diamond Excel® paste). The use of diamond burs (G3) resulted in the highest composite surface roughness. There was no significantly different between G1, G4, G5 and G6