Visão contemporânea sobre pinos anatômicos

As an alternative to improve the adaptation of prefabricated posts in flared canals and weakened roots, the option is for relining prefabricated pin, known as a technique of anatomical post. This technique, which can be made with composite resin increases the adjustment post to the walls of the canal and reduces the cementing line, causing the retaining post is less dependent on the mechanical properties of the cementing agent. This article aims to provide an overview of anatomical posts, specifically in the last two decades, based on studies extracted from Scielo, Scopus and Pubmed, referring to the following terms of MeSH Data Base: custom made fiber post, indirect fiber glass posts, root canal therapy and post and core tecnique. According to the literature review in this article, it can be concluded that this technique has been used by several authors and has been shown effective and promising, it creates an individualized retainer with better adaptation and decreased mechanical imbrication cementing line .

A new calcium silicate-based material (Biodentine) for filling radicular perforation in an endodontic-periodontal lesion: a case report

This case report presents an apical radicular perforation management using new calcium silicate-based cement (Biodentine) in a combined endodontic-periodontal lesion. The presence of apical radicular perforation may interfere in the endodontic treatment prognosis. Radicular perforation filling with bioactive cement through endodontic surgery is a possible treatment. This study presents an apical radicular perforation with periodontal involvement, due to alveolar bone loss on the buccal radicular surface from an incorrect intracanal preparation for the fiber post placing. The chosen alternative was a periapical surgery, the perforation was filled with a silicate and calcium chloride bioactive cement (Biodentine; Septodont, Saint-Maur-des-Fosses Cedex, France), and the radicular surface was etched with citric acid, because the access from root canal was impossible. The follow-up was for 8 months, through clinical and radiographic analysis. At the end of the follow-up, radiographic analyses showed the bone healing, and no clinical changes in periodontal probing depth, gingival recession, and the height of the interproximal mesial and distal papillae were observed. The root perforation treatment has a difficult management, especially when the dental root has a simultaneous periodontal commitment. The Biodentine proves to be a promising material for use in these situations.

Fracture resistance of simulated immature teeth after different intra-radicular treatments

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Influence of storage times on bond strength of resin cements to root canal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sistemas de retenção intrarradicular: considerações teóricas e comportamento biomecânico

The aim of this study was to review the current scientific literature to discuss the biomechanical behavior and characteristics inherent to both cast post and core and the prefabricated posts used in the practice of restoring endodontically treated teeth. To identify studies of this review, it was performed a detailed and advanced search strategy to the databases PubMed and Medline. It was used as descriptors: endodontically treated teeth, post, core, fiber post and metal post. Inclusion criteria were: clinical trials, randomized controlled trials, in vitro studies, literature reviews and systematic reviews with or without meta-analysis of the last 10 years that addressed the theme. Exclusion criteria were: articles without abstracts, animal studies, articles whose language was not English and articles from journals that do not belong to the Dentistry field. Of a total of 35 articles, after an analysis according to inclusion and exclusion criteria, 23 articles were selected. Most of the current scientific literature indicates that the prefabricated fiber reinforced and ceramic posts should be appointed for endodontically treated teeth that have a minimum height of 2mm ferrule. As for the cast metal cores, along with pre-fabricated metal represent a good prosthetic option, when weakened teeth have to be restored for any reason. Despite the large number of studies, there is still a lack of longterm prospective studies that evaluate the effectiveness of these posts in the treatment of endodontically treated teeth.

Efeito na adesão de pinos de fibra de vidro na dentina radicular após irrigação com diferentes formulações de ácido peracético e cimentação com RelyX U200

Pós-graduação em Odontologia - FOAR

Atividade proteolítica e resistência da união cimento resinoso-dentina radicular produzida na presença de agentes promotores de ligações cruzadas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Push-out bond strength and SEM evaluation of a new bonding approach into the root canal

Objective: This study evaluated the performance of different adhesive systems in fiber post placement aiming to clarify the influence of different hydrophobic experimental blend adhesives, and of one commercially available adhesive on the frictional retention during a luting procedure. Material and Methods: One luting agent (70 Wt% BisGMA, 28.5% TEGDMA; 1.5% p-tolyldiethanolamine) to cement fiber posts into root canals was applied with 4 different adhesive combinations: Group 1: The etched roots were rinsed with water for 30 s to remove the phosphoric acid, then rinsed with 99.6% ethanol for 30 s, and blot-dried. A trial adhesive (base to catalyst on a 1: 1 ratio) was used with an experimental luting agent (35% Bis-GMA, 14.37% TEGDMA, 0.5% EDMAB, 0.13% CQ); Group 2: A trial adhesive (base to catalyst on a 1: 2 ratio) was luted as in Group 1; Group 3: One-Step Plus (OSP, Bisco Inc.) following the ethanol bonding technique in combination with the luting agent as in Group 1; Group 4: OSP strictly following the manufacturer's instructions using the luting agent as in Group 1. The groups were challenged with push-out tests. Posted root slices were loaded until post segment extrusion in the apical-coronal direction. Failure modes were analyzed under scanning electron microscopy. Results: Push-out strength was not significantly influenced by the luting agent (p>0.05). No statistically significant differences among the tested groups were found as Group 1 (Exp 1 - ethanol-wet bonding technique)=Group 2 (Exp 2 - ethanol-wet bonding technique)= Group 3 (OSP - ethanol-wet bonding technique)= Group 4 (control, OSP - water-wet bonding technique) (p>0.05). The dominating failure modes in all the groups were cohesive/adhesive failures, which were predominantly observed on the post/luting agent interface. Conclusions: The results of this study support the hypothesis that the proposal to replace water with ethanol to bond fiber posts to the root canal using highly hydrophobic resin is plausible, but this seems to be more the proof of a concept than a clinically applicable procedure.

Are endodontically treated incisors reliable abutments for zirconia-based fixed partial dentures in the esthetic zone?

This ex vivo pilot study tested the influence of defect extension and quartz-fiber post placement (QFP) on the ex vivo survival rate and fracture resistance of root-treated upper central incisors served as abutments for zirconia 2-unit cantilever fixed partial dentures (2U-FPDs) exposed to 10 years of simulated clinical function.

Restauración de incisivo inferior fracturado mediante procedimientos de invasión mínima : reporte de un caso clínico

La odontología está inmersa en un nuevo paradigma: no se puede pensar en ninguna técnica restauradora sin que participen fenómenos de adhesión. El desarrollo de pernos de fibra de vidrio, sumado a los procedimientos de restauraciones adhesivas puede utilizarse como uno de los tantos recursos de la odontología de invasión mínima. Los pernos de fibra de vidrio ofrecen varias ventajas: comportamiento anisótropo, módulo de elasticidad bajo, buena resistencia mecánica, el lecho que aloja al perno de fibra requiere de una mínima preparación y se cementan con cementos adhesivos con carga, permitiendo de esta manera obtener una superficie homogénea que se interpone entre el perno de fibra y los tejidos dentales, conectándolo a los tejidos del conducto y sustituyendo mecánicamente la dentina. El caso clínico que se reporta se presentó para su resolución en la Clínica Integrada III F. O. UNCuyo durante el año lectivo 2009. El paciente presentaba una fractura amelodentinaria desde hacía cuatro años, con compromiso de la vitalidad y un proceso periapical. Durante los procedimientos endodónticos se realizó una perforación de la pared del conducto que se selló mediante la colocación de hidróxido de calcio y la obturación del mismo con conos de gutapercha. Se efectuó el seguimiento clínico y radiográfico del caso en donde se constató la reparación del proceso apical y luego se procedió a la restauración del elemento dentario con resinas compuestas con la ayuda de un poste de fibra de vidrio cementado con cemento resinoso. Dadas las características del tratamiento endodóntico realizado, se decidió dejar más porción del cono de gutapercha a pesar de lo aconsejado por numerosos autores, ya que de esta manera se aseguró el sellado de la perforación radicular para evitar de esta manera la nanofiltración hacia el interior del elemento dentario.

Theoretical and experimental researches of post-micro-buckling for fiber-reinforced composites

Post-microbuckling is a fundamental feature of compressive failure process for the unidirectional-fiber-reinforced composites and laminated composites. The post-microbuckling behavior of composites under compression in the light of the Kevlar49-reinforced 648/BF3.400 (brittle epoxy) and EP (flexible epoxy) is studied, theoretically and experimentally. Analytical results of compressive strength are in good agreement with experimental results, qualitatively and quantitatively. By the experimental research, the post-microbuckling feature of the advancing kink band model is clearly displayed.

Effect of post length on the fatigue resistance of bovine teeth restored with bonded fiber posts: A pilot study

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio.

Confocal laser scanning microscopy investigation of bond interfaces involved in fiber glass post cementation

Objective: This confocal microscopy study evaluated the cement/dentin and cement/post interfaces along theroot canalwallswhenfiberglasspostswerebonded to dentin using different types of cements. Material & Methods: Thirty endodontically treated premolars were divided into 3 groups according to the adhesive materials used in the bonding procedure: Prime & Bond 2.1/Self Cure + Enforce, RelyX Unicem and RelyX Luting. Rhodamine B dye was incorporated in the luting materials for the cementation of the fiber glass posts (Exacto, Angelus) to dentin. Three transversal slices (apical, middle and coronal) were examined under confocal laser scanning microscopy. Statistical analysis was performed using the Kappa, Kruskal-Wallis and Dunnet tests, in a significance level of 5%. Results: The Prime & Bond 2.1/Self Cure + Enforce presented a uniform formation of tags in the dentin but gaps in the cement/dentin interface. The RelyX Unicem and RelyX Luting presented an adhesive interface with a fewer amount of gaps, but showed shorter tag formation than the Enforce system. All cements presented the same pattern of bubbles inside the cements. The RelyX Luting presented a greater amount of cracks inside the cement in comparison with the other cements in the coronal third, while no difference was observed between RelyX Unicem and Enforce. The RelyX Luting showed the lowest quantity of cement penetration into the post. Conclusion: In general, the quality of bonding interfaces of fiber posts luted to root canals was affected by both location and type of cement.

Use of Fiber Reinforced Polymer Composite Cable for Post-tensioning Application

Corrosion of steel tendons is a major problem for post-tensioned concrete, especially because corrosion of the steel strands is often hard to detect inside grouted ducts. Non-metallic tendons can serve as an alternative material to steel for post-tensioning applications. Carbon fiber reinforced polymer (CFRP), given its higher strength and elastic modulus, as well as excellent durability and fatigue strength, is the most practical option for post-tensioning applications. The primary objective of this research project was to assess the feasibility of the use of innovative carbon fiber reinforced polymer (CFRP) tendons and to develop guidelines for CFRP in post-tensioned bridge applications, including segmental bridges and pier caps. An experimental investigation and a numerical simulation were conducted to compare the performance of a scaled segmental bridge model, post-tensioned with two types of carbon fiber strands and steel strands. The model was tested at different prestress levels and at different loading configurations. While the study confirms feasibility of both types of carbon fiber strands for segmental bridge applications, and their similar serviceability behavior, strands with higher elastic modulus could improve structural performance and minimize displacements beyond service loads. As the second component of the project, a side-by-side comparison of two types of carbon fiber strands against steel strands was conducted in a scaled pier cap model. Two different strand arrangements were used for post-tensioning, with eight and six strands, respectively representing an over-design and a slight under-design relative to the factored demand. The model was tested under service and factored loads. The investigation confirmed the feasibility of using carbon fiber strands in unbonded post-tensioning of pier caps. Considering both serviceability and overload conditions, the general performance of the pier cap model was deemed acceptable using either type of carbon fiber strands and quite comparable to that of steel strands. In another component of this research, creep stress tests were conducted with carbon fiber composite cable (CFCC). The anchorages for all the specimens were prepared using a commercially available expansive grout. Specimens withstood 95% of the guaranteed capacity provided by the manufacturer for a period of five months, without any sign of rupture.