Avaliação do selamento de ápices radiculares retrobturados ou recobertos com diferentes materiais mediante infiltração marginal por corante e análise da interface em microscopia eletrônica de varredura

The purpose of this study was to evaluate the apical sealing ability and the marginal adaptation of five dental materials used in retrofillings or applied to the bevelled root surface. One hundred and forty extracted single rooted human teeth were used, divided into seven groups of twenty each. ln the first, second, third and fourth groups, the teeth were apicoectomized, submitted to cavity preparations and retrofilled with one of the following materiais: zinc free silver amalgam, a dentin bonding system plus composite resin, a glass ionomer cement ora compomer. In the fifth, sixth and seventh groups, the teeth were apicoectomized and capped on the bevelled root surface with one of the following materiais: a dentin bonding system plus composite resin, a glass ionomer cement or a compomer. Two specimens of each experimental group were evaluated for the marginal adaptation using scanning electron microscopy. The remaining 126 specimens were immersed in 2% methylene blue dye, stored for one week at 37ºC and the infiltration was evaluated with a stereomicroscope. The results showed that the glass ionomer cement presented the lowest values of marginal infiltration when used as retrofilling material, with a significant statistical difference when compared with the others tested materials. When used as apical capping, the glass ionomer cement and the compomer were equivalent and significantly better than the dentin bonding system plus composite resin. Using scanning electron microscopy, all the materials showed some slight adjustment problem. ln the retrofilling, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin, while the largest were observed with the glass ionomer cement and zinc free silver amalgam. ln the apical capping, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin and ...

Efeito de diversos protocolos de dessensibilização dentinária na obliteração de túbulos dentinários, resistência de união do sistema adesivo e formação de camada hibrida na dentina cervical

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de diversos protocolos de dessensibilização dentinária na obliteração de túbulos dentinários, resistência de união do sistema adesivo e formação de camada hibrida na dentina cervical

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials

Objective: The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus) combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany). Material and Methods: Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC) and immersed in a 50-wt% aqueous silver nitrate solution at 37 degrees C (24 h). After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM). The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS). The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (alpha=0.05). Results: Epiphany presented more regions containing gaps between dentin and sealer (p<0.05). There was correspondence between the presence of gaps and microleakage (p<0.05). Microleakage was similar among the root-filling materials (p>0.05). Conclusions: The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.

Effect of 2% chlorhexidine digluconate on bond strength of a glass-fibre post to root dentine

Aim: To assess the immediate influence of dentine bonding systems (DBS) associated with 2% chlorhexidine digluconate (CHX) on glass-fibre post-bond strength to root dentine, in terms of coronal, middle and apical thirds. Methodology: Sixty bovine roots were root filled and randomly assigned to 1 of 6 groups (n = 10): SBMP (3-step etch-and-rinse system, Scotchbond Multi-Purpose), SB (2-step etch-and-rinse system, Single Bond 2), SE (2-step self-etching system, Clearfil SE Bond) and SBMP-CHX, SB-CHX and SE-CHX, respectively, associated with CHX. For all groups, a glassfibre post was luted with a dual-cure resin cement, RelyX ARC. After 7-day storage, specimens were subjected to the push-out test. Failure modes were analysed under optical microscopy (40x). Bond strength values were statistically analysed by two-way ANOVA and Bonferroni tests (P < 0.05). Results: The effect of DBS was significant (P < 0.05), and SE reached higher bond strength in comparison with the other DBS tested. CHX association did not show improvement with any DBS (P > 0.05); rather, it negatively affected SE, which was detected for all thirds. There was no difference between thirds (P > 0.05), except for the SE-CHX, which presented lower values for the apical third (P < 0.05). Adhesive cement/dentine adhesive failure was predominant for all groups. CHX did not influence the failure mode for any DBS (P > 0.05). Conclusions: The performance of the dentine bonding systems was material dependent. CHX did not improve immediate bond strength; however, CHX negatively affected the bond strength of the self-etching system, especially in the third apical

Protocolos para a colocação e remoção de espigões

A utilização de espigões em dentes tratados endodonticamente é um dos temas mais estudados em Medicina Dentária. As opiniões são divergentes em relação aos procedimentos clínicos e materiais a serem utilizados para a colocação e remoção de espigões. O objetivo deste trabalho foi realizar uma revisão bibliográfica de forma a organizar conceitos e princípios clínicos para melhor esclarecer os fatores que determinam a necessidade de colocação, utilização e escolha do tipo de espigão, sua cimentação e técnicas para a remoção. Foram analisadas as características e propriedades dos cimentos de fosfato de zinco, ionômero de vidro, cimentos resinosos de polimerização química, polimerização dupla, foto-polimerizável e os sistemas adesivos etch and rinse, self etch e autoadesivos, bem como as técnicas para a remoção de espigões cimentados com diferentes cimentos e sistemas adesivos para depois acessar o remanescente de guta percha para o retratamento endodôntico. Foi feita uma pesquisa bibliográfica na base de dados electrónica PubMed, Google Scholar e RCAAP com as seguintes palavras chave: “Espigões”; “Retratamento Endodôntico”; “Ionómero de Vidro”; “Fosfato de Zinco”; “Cimentos Resinosos”; “Posts”; “Endodontic Retreatment”; “Glass Ionomer”; Zinc-phosphate”; “Resin Cements"; “Push Out Test”; “Posts AND Removal”. Concluiu-se que a cimentação de espigões pré-fabricados de fibra de vidro com cimentos resinosos de dupla polimerização associados aos sistemas adesivos self etch estão gradualmente substituindo os outros tipos de espigões e demais cimentos e possibilitam restaurar o dente de forma adequada e duradoura. E o uso de ultrassons apresenta maior eficácia e segurança na remoção dos espigões.

Bonding of restorative materials to dentin with various luting agents

The aim was to compare eight types of luting agents when used to bond six indirect, laboratory restorative materials to dentin. Cylinders of the six restorative materials (Esteticor Avenir [gold alloy], Tritan [titanium], NobelRondo [feldspathic porcelain], Finesse All-Ceramic [leucite-glass ceramic], Lava [zirconia], and Sinfony [resin composite]) were ground and air-abraded. Cylinders of feldspathic porcelain and glass ceramic were additionally etched with hydrofluoric acid and were silane-treated. The cylinders were luted to ground human dentin with eight luting agents (DeTrey Zinc [zinc phosphate cement], Fuji I [conventional glass ionomer cement], Fuji Plus [resin-modified glass ionomer cement], Variolink II [conventional etch-and-rinse resin cement], Panavia F2.0 and Multilink [self-etch resin cements], and RelyX Unicem Aplicap and Maxcem [self-adhesive resin cements]). After water storage at 37°C for one week, the shear bond strength of the specimens (n=8/group) was measured, and the fracture mode was stereomicroscopically examined. Bond strength data were analyzed with two-factorial analysis of variance (ANOVA) followed by Newman-Keuls' Multiple Range Test (?=0.05). Both the restorative material and the luting agent had a significant effect on bond strength, and significant interaction was noted between the two variables. Zinc phosphate cement and glass ionomer cements produced the lowest bond strengths, whereas the highest bond strengths were found with the two self-etch and one of the self-adhesive resin cements. Generally, the fracture mode varied markedly with the restorative material. The luting agents had a bigger influence on bond strength between restorative materials and dentin than was seen with the restorative material.

Deproteinized dentin: A favorable substrate to self-bonding resin cements?

The adhesive performance on deproteinized dentin of different self-adhesive resin cements was evaluated through microtensile bond strength (mu TBS) analysis and scanning electron microscopy (SEM). Occlusal dentin of human molars were distributed into different groups, according to the categories: adhesive cementation with two-step bonding systems-control Groups (Adper Single Bond 2 + RelyX ARC/3M ESPE; One Step Plus + Duolink/Bisco; Excite + Variolink I/Ivoclar Vivadent) and self-adhesive cementation-experimental groups (Rely X Unicem/3M ESPE; Biscem/Bisco; MultiLink Sprint/Ivoclar Vivadent). Each group was subdivided according to the dentin approach to: alpha, maintenance of collagen fibers and beta, deproteinization. The mean values were obtained, and submitted to ANOVA and Tukey test. Statistical differences were obtained to the RelyX Unicem groups (alpha = 13.59 MPa; beta = 30.19 MPa). All the BIS Group specimens failed before the mechanical tests. Dentinal deproteinization provided an improved bond performance for the self-adhesive cement Rely X Unicem, and had no negative effect on the other cementing systems studied. (C) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 98B: 387-394, 2011.

Shear bond strength of self-etch and total-etch bonding systems at different dentin depths

The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond) in regards to buccal and lingual surfaces and dentin depth. Forty extracted third molars had roots removed and crowns bisected in the mesiodistal direction. The buccal and lingual surfaces were fixed in a PVC/acrylic resin ring and were divided into buccal and lingual groups assigned to each selected adhesive. The same specimens prepared for the evaluation of superficial dentin shear resistance were used to evaluate the different depths of dentin. The specimens were identified and abraded at depths of 0.5, 1.0, 1.5 and 2.0 mm. Each depth was evaluated by ISO TR 11405 using an EMIC-2000 machine regulated at 0.5 mm/min with a 200 Kgf load cell. We performed statistical analyses on the results (ANOVA, Tukey and Scheffé tests). Data revealed statistical differences (p < 0.01) in the adhesive and depth variation as well as adhesive/depth interactions. The Adper Single Bond 2 demonstrated the highest mean values of shear bond strength. The Prompt L-Pop product, a self-etching adhesive, revealed higher mean values compared with Magic Bond DE and Self Etch Bond adhesives, a total and self-etching adhesive respectively. It may be concluded that the shear bond strength of dentin is dependent on material (adhesive system), substrate depth and adhesive/depth interaction.

Morphological analysis of glass, carbon and glass/carbon fiber posts and bonding to self or dual-cured resin luting agents

OBJECTIVE: The aim of this study was to evaluate the morphology of glass (GF), carbon (CF) and glass/carbon (G/CF) fiber posts and their bond strength to self or dual-cured resin luting agents. MATERIAL AND METHODS: Morphological analysis of each post type was conducted under scanning electron microscopy (SEM). Bond strength was evaluated by microtensile test after bisecting the posts and re-bonding the two halves with the luting agents. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Failure modes were evaluated under optical microscopy and SEM. RESULTS: GF presented wider fibers and higher amount of matrix than CF, and G/CF presented carbon fibers surrounded by glass fibers, and both involved by matrix. For CF and GF, the dual-cured material presented significantly higher (p<0.05) bond strength than the self-cured agent. For the dual agent, CF presented similar bond strength to GF (p>0.05), but higher than that of G/CF (p<0.05). For the self-cured agent, no significant differences (p>0.05) were detected, irrespective of the post type. For GF and G/CF, all failures were considered mixed, while a predominance of adhesive failures was detected for CF. CONCLUSION: The bonding between fiber posts and luting agents was affected by the type of fibers and polymerization mode of the cement. When no surface treatment of the post is performed, the bonding between glass fiber post and dual-cured agent seems to be more reliable.

Application of hydrophobic resin adhesives to acid-etched dentin with an alternative wet bonding technique

Hydrophilic dentin adhesives are prone to water sorption that adversely affects the durability of resin-dentin bonds. This study examined the feasibility of bonding to dentin with hydrophobic resins via the adaptation of electron microscopy tissue processing techniques. Hydrophobic primers were prepared by diluting 2,2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl] propane/triethyleneglycol dimethacrylate resins with known ethanol concentrations. They were applied to acid-etched moist dentin using an ethanol wet bonding technique that involved: (1) stepwise replacement of water with a series of increasing ethanol concentrations to prevent the demineralized collagen matrix from collapsing; (2) stepwise replacement of the ethanol with different concentrations of hydrophobic primers and subsequently with neat hydrophobic resin. Using the ethanol wet bonding technique, the experimental primer versions with 40, 50, and 75% resin exhibited tensile strengths which were not significantly different from commercially available hydrophilic three-step adhesives that were bonded with water wet bonding technique. The concept of ethanol wet bonding may be explained in terms of solubility parameter theory. This technique is sensitive to water contamination, as depicted by the lower tensile strength results from partial dehydration protocols. The technique has to be further improved by incorporating elements of dentin permeability reduction to avoid water from dentinal tubules contaminating water-free resin blends during bonding. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res 84A: 19-29, 2008.

Solubility study of phytochemical cross-linking agents on dentin stiffness

Objectives: The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin were investigated. Methods: Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5 mm x 1.7 mm x 7 mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240 min. Results: The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p < 0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4 h of treatment, while COE produced strongest enhancement when dissolved in ethanol:water. Conclusions: The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA-dentin matrix interaction. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of oxalate desensitizers and dentin moisture during total-etch bonding

Purpose: To evaluate the effect of oxalate during total-etch bonding, under different dentin moisture conditions, over time. The null hypothesis tested was that microtensile bond strength (mu TBS) was not affected by oxalate treatment and dentin moisture during two evaluation periods. Methods: Extracted human third molars had their mid-coronal dentin exposed flat and polished with 600-grit SiC paper. The surfaces were etched with 35% phosphoric acid for 15 seconds, washed and blot dried. After etching, a 3% potassium oxalate gel was applied for 120 seconds, except for the control group (no desensitizer). The surface was then washed and left moist (Wet bonding) or air-dried for 30 seconds (Dry bonding). The surfaces were bonded with: (I) two 2-step etch-and-rinse adhesives: Single Bond (SB); Prime & Bond NT (PBNT) and (2) one 3-step etch-and-rinse adhesive: Scotchbond Multi Purpose (SBMP). Composite buildups were constructed incrementally with Tetric Ceram resin composite. Each increment was cured for 40 seconds. After storage in water for 24 hours or 1 year at 37 C, the specimens were prepared for mu TBS testing with a cross-sectional area of approximately 1 mm(2). They were then tested in tension in an Instron machine at 0.5 mm/minute. Data were analyzed by ANOVA and Student-Newman-Keuls at alpha = 0.05. Results: Application of potassium oxalate had no significant effect on the bond strengths of SBMP and PBNT, regardless of the surface moisture condition (P > 0.05). Conversely, reduced bond strengths were observed after oxalate treatment for SB in both moisture conditions, that being significantly lower when using a dry-bonding procedure (P < 0.05). Lower bond strength was obtained for PBNT when a dry-bonding technique was used, regardless of the oxalate treatment (P < 0.05). After aging the specimens for 1 year, bond strengths decreased. Smaller reductions were observed for SBMP, regardless of moisture conditions. For the WB technique, smaller reductions after 1 year were observed without oxalate treatment for SB and after oxalate treatment for PBNT. (Am J Dent 2010;23:137-141).

Bonding of Composite Resin to Alumina and Zirconia Ceramics with Special Emphasis on Surface Conditioning and Use of Coupling Agents

Dental oxide ceramics have been inspired by their biocompability and mechanical properties which have made durable all-ceramic structures possible. Clinical longevity of the prosthetic structures is dependent on effective bonding with luting cements. As the initial shear bond strength values can be comparable with several materials and procedures, long-term durability is affected by ageing. Aims of the current study were: to measure the shear bond strength of resin composite-to-ceramics and to evaluate the longevity of the bond; to analyze factors affecting the bond, with special emphasis on: the form of silicatization of the ceramic surface; form of silanization; type of resin primer and the effect of the type of the resin composite luting cement; the effect of ageing in water was studied regarding its effect to the endurance of the bond. Ceramic substrates were alumina and yttrium stabilized zirconia. Ceramic conditioning methods included tribochemical silicatization and use of two silane couplings agents. A commercial silane primer was used as a control silane. Various combinations of conditioning methods, primers and resin cements were tested. Bond strengths were measured by shear bond strength method. The longevity of the bond was generally studied by thermocycling the materials in water. Additionally, in one of the studies thermal cycling was compared with long-term water storaging. Results were analysed statistically with ANOVA and Weibull analysis. Tribochemical treatment utilizing air pressure of 150 kPa resulted shear bond strengths of 11.2 MPa to 18.4 MPa and air pressure of 450 kPa 18.2 MPa to 30.5 MPa, respectively. Thermocycling of 8000 cycles or four years water storaging both decreased shear bond strength values to a range of 3.8 MPa to 7.2 MPa whereas initial situation varied from 16.8. Mpa to 23.0 MPa. The silane used in studies had no statistical significance. The use of primers without 10-MDP resulted spontaneous debonding during thermocycling or shear bond strengths below 5 MPa. As conclusion, the results showed superior long-term bonding with primers containing 10-MDP. Silicatization with silanizing showed improved initial shear bond strength values which considerably decreased with ageing in water. Thermal cycling and water storing for up to four years played the major role in reduction of bond strength, which could be due to thermal fatigue of the bonding interface and hydrolytic degradation of the silane coupled interface.

Changes in the stiffness of demineralized dentin following application of tooth whitening agents

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