Avaliação da resistencia a fratura de raizes debilitadas reconstruidas morfologicamente com materiais adesivos

Tese (Livre-docencia) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Várias exodontias de raízes são indicadas em função de cárie, preparo intra-radicular incorreto, remoção de pinos e núcleos. A preservação dessas raizes pelo preenchimento do conduto radicular com materiais adesivos tem sido relatada na literatura. O objetivo desta pesquisa foi avaliar a resistência à fratura de raízes debilitadas preenchidas com materiais adesivos, empregando-se dentes uni-radiculares com núcleos fundidos cimentados, nas seguintes condições: controle positivo (preparo convencional), controle negativo (raízes debilitadas), raízes preenchidas com ionômeros, raízes preenchidas com ionômero fotoativado, raízes preenchidas com sistemas adesivo/compósito. Os materiais testados foram: ionômero tipo II modificado (Chelon-Silver), ionômero tipo III (Ketac-Bond), ionômero fotoativado (Vitremer), compósitos (Herculite XRV e Z 100). Após remoção da coroa clínica dos dentes, eram preparadas as raízes para receberem os devidos tratamentos. Confeccionados os padrões em resina acrílica, os mesmos eram incluídos e fundidos. Obtidos os núcleos em liga de Cu-Al, eram adaptados e cimentados no interior do conduto. Os corpos de prova eram então submetidos a carregamento em máquina de ensaio universal até ruptura da raiz. Os resultados foram expressos em kgf, tabulados e analisados estatisticamente. Concluiu-se que: entre os materiais testados o compósito Z 100 teve melhor desempenho que todos os demais e inclusive quanto ao controle positivo; o ionômero Vitremer, o compósito XRV e o Chelon-Silver apresentaram resultados semelhantes entre si e ao controle positivo; o ionômero Ketac-Bond teve comportamento desfavorável em relação a todos os outros e semelhante ao controle negativoAbstract: Several dental roots extractions have been indicated due to carie, incorrected intra-root preparations, remotions of pin and post. The aim of this research was to evaluate the resistence fracture of debilitated root filled with adhesive materials. Unirradicular with cast and cemented post were utilized in the following conditions: positive control (conventional preparation), negative control (debilitated root), roots filled with glass ionomer (Chelon-Silver and Ketac Bond), root filled with light cured glass ionomer (Vitremer), root filled with composite/adhesive system (Herculite XRV and Z 100). After remotion of clinical crown teeth, the roots were prepared and acrilic resin mold were obtained and after, included and cast. The metallic post in Cu-Al were adapted and cemented in the root. The samples were submited to compressive strenght in an universal testing machine until rupture. The results were expressed in Kgf and analized statistically. It was concluded that: among the tested materials, the composite Z 100 presented the best performance if compared with whole materials including positive control; the Vitremer ionomer, the composite XRV, Chelon-Silver and positive control presented similar results; the Ketac-Bond ionomer had unfavorable performance in relation of all sample and similar to negative controlLivre DocênciaDentísticaLivre-Docente em Clinica Odontologic

Effect of relining on fiber post retention to root canal

One of the clinically relevant problems dentists face when restoring endodontically treated teeth is the mismatch between fiber post and post space diameters, which results in an excessively thick resin cement layer. Fiber post relining appears as a solution for this problem. OBJECTIVES: The aim of this study was to evaluate the effect of fiber post relining with composite resin on push-out bond strength. MATERIAL AND METHODS: Twenty bovine incisors were selected to assess post retention. The crowns were removed below the cementoenamel junction and the root canals were treated endodontically and flared with diamond burs. The roots were allocated into two groups (n=10): G1: fiber posts without relining and G2: fiber posts relined with composite resin. The posts were cemented with a dual-cured resin cement and the specimens were sectioned transversally. Three 1.5-mm thick slabs were obtained per root and identified as cervical, medium and apical thirds. The push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. The failure mode of fractured specimens was analyzed under scanning electron microscopy. Data were analyzed by split-plot ANOVA and post-hoc Tukey's test at a pre-set alpha of 0.05. RESULTS: Relined fiber posts presented higher retention values than non-relined post in all thirds. No statistically significant differences (p>;0.05) were found among thirds for relined posts. All failures occurred at the interface between resin cement and root dentin. CONCLUSIONS: Relining with composite resin seems to be an effective method to improve the retention of fiber posts to flared root canals

Optimization of the etch-and-rinse technique : New perspectives to improve resin–dentin bonding and hybrid layer integrity by reducing residual water using dimethyl sulfoxide pretreatments

Objective. To determine whether bonding effectiveness and hybrid layer integrity on acid-etched dehydrated dentin would be comparable to the conventional wet-bonding technique through new dentin biomodification approaches using dimethyl sulfoxide (DMSO). Methods. Etched dentin surfaces from extracted sound molars were randomly bonded in wet or dry conditions (30 s air drying) with DMSO/ethanol or DMSO/H2O as pretreatments using a simplified (Scotchbond Universal Adhesive, 3M ESPE: SU) and a multi-step (Adper Scotchbond Multi-Purpose, 3M ESPE: SBMP) etch-and-rinse adhesives. Untreated dentin surfaces served as control. Bonded teeth (n=8) were stored in distilled water for 24 h and sectioned into resin-dentin beams (0.8 mm(2)) for microtensile bond strength test and quantitative interfacial nanoleakage analysis (n = 8) under SEM. Additional teeth (n = 2) were prepared for micropermeability assessment by CFLSM under simulated pulp ar pressure (20 cm H2O) using 5 mM fluorescein as a tracer. Microtensile data was analyzed by 3-way ANOVA followed by Tukey Test and nanoleakage by Kruskal-Wallis and Dunn-Bonferroni multiple comparison test (alpha = 0.05). Results. While dry-bonding of SBMP produced significantly lower bond strengths than wet-bonding (p Conclusion. DMSO pretreatments may be used as a new suitable strategy to improve bonding of water-based adhesives to demineralized air-dried dentin beyond conventional wetbonding. Less porous resin-dentin interfaces with higher bond strengths on air-dried etched dentin were achieved; nonetheless, overall efficiency varied according to DMSO's co-solvent and adhesive type. Clinical significance. DMSO pretreatments permit etched dentin to be air-dried before hybridization facilitating residual water removal and thus improving bonding effectiveness. This challenges the current paradigm of wet-bonding requirement for the etch-and-rinse approach creating new possibilities to enhance the clinical longevity of resin-dentin interfaces. (C) 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.Peer reviewe

Effect Of The Adhesive Application Mode And Fiber Post Translucency On The Push-out Bond Strength To Dentin.

This study evaluated the effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin. Bovine roots were endodontically treated, and 10 roots were used for each adhesive application mode: PB (Prime&Bond 2.1), PB + SC (Self-cure activator), PB + SBM (Scotchbond Multi-purpose adhesive system), BB (Brush&Bond), BB + CAT (chemical catalyst), and BB + SBM. The translucent Light-Post and Aestheti-Post were cemented. The roots/cemented posts were transversally sectioned to originate three thirds (cervical, middle, and apical). The push-out test was performed, and the failure mode of fractured specimens was analyzed. There was no difference between the fiber posts. For PB and BB, the use of hydrophobic adhesive resin SBM increased post bond strength. The use of SC and CAT catalyst did not affect the push-out bond strength values. The apical third presented the lowest bond strengths.331078-8

Effect Of Dimethyl Sulfoxide Wet-bonding Technique On Hybrid Layer Quality And Dentin Bond Strength.

This study examined the effect of a dimethyl sulfoxide (DMSO) wet bonding technique on the resin infiltration depths at the bonded interface and dentin bond strength of different adhesive systems. Flat dentin surfaces of 48 human third molars were treated with 50% DMSO (experimental groups) or with distilled water (controls) before bonding using an etch-and-rinse (SBMP: Scotchbond Multi-Purpose, 3M ESPE) or a self-etch (Clearfil: Clearfil SE Bond, Kuraray) adhesive system. The restored crown segments (n=12/group) were stored in distilled water (24h) and sectioned for interfacial analysis of exposed collagen using Masson's Trichrome staining and for microtensile bond strength testing. The extent of exposed collagen was measured using light microscopy and a histometric analysis software. Failure modes were examined by SEM. Data was analyzed by two-way ANOVA followed by Tukey Test (α=0.05). The interaction of bonding protocol and adhesive system had significant effects on the extension of exposed collagen matrix (p0.05). DMSO-wet bonding was effective to improve the quality of resin-dentin bonds of the tested etch-and-rinse adhesives by reducing the extent of exposed collagen matrix at the base of the resin-dentin biopolymer. The improved penetration of adhesive monomers is reflected as an increase in the immediate bond strength when the DMSO-wet bonding technique is used with a water-based etch-and-rinse adhesive.31676-68

Influence of root depth and the posttype on Knoop hardness of a dualcured resin cement

Fiber posts are usually luted to the root canal with dual-cured resin cements. However, some of these cements require light-activation in order to reach optimal degree of cure. The aim of this study was to evaluate the effect of the fiber post type on microhardness of a dualcured resin cement used for luting these posts. After endodontic treatment, four fiber post types were luted to the root canal of bovine incisors with RelyX ARC. The samples were sectioned in order to obtain four slices, representing different depths (0.0; 2.5; 5.0; 7.5 and 10.0mm). Knoop microhardness testing was performed in each slice. The data were submitted to split-plot ANOVA and Tukey post-hoc tests. An additional sample per fiber post type was used to analyze bonding interface by SEM. At the depths of 0 and 2.5 mm, the resin cement presented the highest hardness values. The lowest values were observed at the 10 mm depth, and the resin cement presented intermediary hardness means at the depths of 5 mm and 7.5 mm. By means of scanning electronic microscopy, it was possible to see the more homogeneous hybrid layer in the cervical region of the root

Microtensile Bond Strength Of Methacrylate And Silorane Resins To Enamel And Dentin.

The aim of this study was to evaluate the microtensile bond strength (µTBS) of two substrates (enamel and dentin) considering two study factors: type of composite resin [methacrylate-based (Filtek Supreme) or silorane-based (Filtek LS)] and aging time (24 h or 3 months). Twenty human molars were selected and divided into 2 groups (n=10) considering two dental substrates, enamel or dentin. The enamel and dentin of each tooth was divided into two halves separated by a glass plate. Each tooth was restored using both tested composite resins following the manufacturer's instructions. The samples were sectioned, producing 4 sticks for each composite resin. Half of them were tested after 24 h and half after 3 months. µTBS testing was carried out at 0.05 mm/s. Data were analyzed by three-way ANOVA and Tukey's HSD tests at α=0.05. Significant differences between composite resins and substrates were found (p<0.05), but no statistically significant difference was found for aging time and interactions among study factors. The methacrylate-based resin showed higher µTBS than the silorane-based resin. The µTBS for enamel was significantly higher than for dentin, irrespective of the composite resin and storage time. Three months of storage was not sufficient time to cause degradation of the bonding interaction of either of the composite resins to enamel and dentin.25327-3