Browsing by Author "Fernandes, Valter"
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- Contaminação de resinas compostas no ambiente clínico - um estudo in vitroPublication . Torres, Orlanda; Cunha, Ivana; Fidalgo-Pereira, Rita; Fernandes, Valter; Henriques, Bruno; Souza, Júlio C. M.Objetivos: O objetivo do presente estudo foi a avaliação da contaminação de resinas compostas utilizando luvas de latex e luvas de nitrilo, instrumental e contaminantes do ambiente clínico. Materiais e métodos: Seis resinas compostas nano híbridas foram divididas em grupos: (A) grupo controlo, sem manuseio ou contaminação, (B) Luvas de nitrilo sem pó, (C) luvas de latex com pó, (D) luvas de nitrilo sem pó com saliva, (E) luvas de latex com pó com saliva, (F) luvas de nitrilo sem pó contaminadas com sangue humano, (G) luvas de latex com pó contaminadas com sangue humano. As resinas compostas pertencentes aos diferentes grupos foram fotopolimerizadas durante 40 s com fotopolimerizador de 400 mW/cm2 e analisadas através microscopia ótica entre 30x e 500x de ampliação. As amostras foram também analisadas através de microscopia eletrónica de varrimento em diferentes ampliações que variaram entre 50x e 8000x. Resultados: O grupo referente ao manuseio de resinas compostas com luvas de nitrilo sem pó ou espátulas clínicas evitou a presença de contaminantes, todavia foi observado um aspeto morfológico heterogéneo das resinas compostas devido à formação de aglomerados que ficaram aprisionados. Por intermédio da microscopia eletrónica de varrimento foi possível detetar, nas luvas com pó, amido de milho. Adicionalmente foram detetados micro espaços, após manuseio com luvas de latex com pó. Os provetes manuseados com luvas de latex e de nitrilo contaminados com saliva, demonstraram a presença glicoproteínas e compostos á base de cálcio como cloretos, fosfatos e carbonatos na camada de condicionamento. Após manuseamento com sangue, hemoderivados foram transferidos das luvas contaminadas para as resinas compostas após manuseio. Conclusões: No ambiente clínico as resinas compostas são suscetíveis à contaminação com detritos provenientes de luvas com pó. Contaminantes como saliva e sangue presentes durante o manuseio, são absorvidos e aprisionados nas resinas compostas durante o manuseio clínico, provocando defeitos nas resinas compostas, tais como micro e macro bolhas ou aglomerados de contaminantes.
- Fitting of different intraradicular composite posts to oval tooth root canals: a preliminary assessmentPublication . Fernandes, Valter; Fidalgo-Pereira, Rita; Edwards, Jane; Silva, Filipe; Özcan, Mutlu; Carvalho, Óscar; Souza, Júlio C. M.The purpose of the present study was to perform a preliminary analysis of the fitting of different fiber-reinforced composite (GFRC) posts to tooth root canals and determine the resin cement layer thickness. The following GFRC posts were assessed: bundle posts (Rebilda GTTM, VOCO, Germany), sleeve system (SAPTM, Angelus Ind, Brazil), and accessory posts (ReforpinTM, Angelus, Brazil). Twenty-four freshly extracted mandibular single-rooted pre-molars were endodontically treated and divided into six groups, according to the type of GFRC post and resin cement (self-adhesive or conventional dual-cured). Then, specimens were cross-sectioned and inspected by optical microscopy regarding the cement layer thickness and presence of defects such as pores, voids, or fissures were assessed. Bundle and accessory posts revealed a regular distribution of resin cement with a lower number of voids than found with sleeve systems. The sleeve system posts showed poor fitting at the apical portion of the root canals. The type of resin cement did not affect the thickness of the interface, although both bundle and accessory posts allow a better distribution of resin cement and fibers. The present preliminary study reveals interesting insights on the fitting of bundle and accessory posts to root dentin and resin cement layer thickness in oval-shape root canals. The sleeve system posts showed adequate fitting only at the coronal portion of the canals.
- Laser-texturing and traditional surface modification to improve the adhesion of glass fiber-reinforced composite posts to resin cementsPublication . Fernandes, Valter; Carvalho, Oscar; Silva, Filipe; Henriques, Bruno; Özcan, Mutlu; Souza, Júlio C. M.Objectives The aim of this study was to perform experimental evaluation of the synergistic effects of laser-texturing and different traditional surface modification approaches to improve the push-out bond strength of glass fiber-reinforced composite (GFRC) posts to resin-matrix cements used in endodontically treated teeth rehabilitation. Methods One hundred and ten freshly extracted mandibular single-rooted premolars were endodontically treated and groups of specimens were divided according to the GFRC cementation after different surface treatment, as follow (n = 10): silane-based conditioning (SIL); 9.7 % HF acid-etching (HF); 35 % H2O2 etching (H2O2); grit-blasting (GB); HF plus H2O2 etching (HFH2O2); 6 W Nd:YAG laser-texturing (L6W); 4.5 W Nd:YAG laser-texturing (L4.5W); 3 W Nd:YAG laser-texturing (L3W); 3 W Nd:YAG plus 35 % H2O2 (L3WH2O2); 3 W Nd:YAG plus SIL (L3WSIL); and no-treatment (C). GFRC posts were cemented into the tooth root canals using a dual-cured resin cement. Then, specimens were cross-sectioned and mechanically assessed by push-out bond strength tests. Specimens were inspected by optical microscopy and scanning electron microscopy at magnification from × 30 up to × 2000. Data were analyzed using one-way analysis of variance and Tukey post hoc test (p = 0.05). Results Surface analyses of the GFRC posts showed a rough and retentive morphological aspect with a removal of the outer epoxy matrix layer and exposure of glass fibers after laser-texturing, grit-blasting or etching under 35 % H2O2. The highest bond strength values at 21.8 MPa was recorded for GFRC posts after laser-texturing on 3W plus silane-based conditioning followed by the group etched with 35 % H2O2 (20.5 MPa). The failure mode was characterized as cohesive and mixed pathways. The lowest bond strength values around 5 and 9 MPa were recorded for untreated GFRC surfaces or specimens etched with HF that was noticeable by adhesive failure pathways. Conclusions The combination of acidic etching and silane conditioning with laser-texturing at medium intensity promoted an adequate surface modification of GFRC posts and increased adhesion to a resin-matrix cement. Such combination of physicochemical approaches can enhance the long-term mechanical behavior of the restorative interface at endodontically treated teeth. Clinical relevance Combining traditional and novel physicochemical approaches can provide promising adhesion pathways for glass fiber-reinforced composite posts to resin-matrix cements. A high mechanical interlocking of the resin-matrix cements and stable retention of the teeth root intracanal posts can decrease the risks of clinical failures by fracture and detachment of the adhesive interface.
- Onlays de resina composta CAD/CAM, avaliação da interface adesiva - Um estudo in vitroPublication . Fidalgo-Pereira, Rita; Magalhães, Tiago; Torres, Orlanda; Carvalho, Óscar; Fernandes, Valter; Souza, Júlio C. M.
- Onlays de resina composta CAD/CAM, avaliação da interface adesiva - Um estudo in vitroPublication . Fidalgo-Pereira, Rita; Magalhães, Tiago; Torres, Orlanda; Carvalho, Óscar; Fernandes, Valter; Souza, Júlio C. M.
- Surface modification of glass fiber-reinforced composite posts by hydrogen peroxide: a scoping reviewPublication . Fernandes, Valter; Tuttle, Camilia; Carvalho, Óscar; Henriques, Bruno; Oliveira, Antonio Pedro Novaes de; Özcan, Mutlu; Souza, Júlio C. M.On the rehabilitation of endodontic treated teeth using intraradicular retention, adhesive failures often occur between the intraradicular post and the resin-matrix cement. The main aim of this study was to conduct a scoping review on the surface modification of glass fiber-reinforced composite posts by hydrogen peroxide solutions. An electronic search was performed in the PubMed database, using combinations of keywords pursuing articles published between 2010 and 2024 in English language. Of the 13 selected studies, 12 investigated the bond strength between the glass fiber-reinforced composite (GFRC) post and the resin-matrix cement after the surface treatment of the post, 5 articles analyzed failures using a stereomicroscope, and 7 studies analyzed the surface topography by scanning electron microscopy (SEM). Etching procedures with hydrogen peroxide (H2O2) altered the surface of the GFRC post by selectively dissolving the matrix without damaging the fibers, resulting in a larger surface area of exposed fibers available to react with the adhesive system or silane. Studies revealed high bond strength values between the etched GFRC posts to the resin-matrix materials. Surface treatment of GFRC posts with hydrogen peroxide seems promising considering the feasibility on the surface modification resulting in the improvement of bond strength of intraradicular posts to resin-matrix cements.
- Transmitância ótica de resinas compostas na cimentação de restaurações indiretas - um estudo in vitroPublication . Fidalgo-Pereira, Rita; Fernandes, Valter; Carvalho, Óscar; Torres, Orlanda; Catarino, Susana O.; Souza, Julio C. M.