Does the moment of fiber post cutting influence on the retention to root dentin?

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Does the Moment of Fiber Post Cutting Influence on the Retention to Root Dentin?

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Apesar das diversas vantagens associadas aos pinos de fibra de vidro pré-fabricados, o corte da sua porção coronária deve ser realizado para permitir seu uso em algumas situações clínicas. Entretanto, o corte do pino cimentado pode gerar tensões na interface adesiva e afetar a resistência de união. O objetivo deste estudo foi avaliar o efeito do momento do corte do pino na resistência de união ao canal radicular. Sessenta raízes de incisivos bovinos foram incluídas em cilindros de resina com simulação do ligamento periodontal. Pinos de fibra de vidro foram cimentados utilizando um cimento resinoso convencional RelyX ARC (3M ESPE) ou autoadesivo RelyX Unicem (3M ESPE). Os pinos foram cortados previamente à cimentação, imediatamente após a cimentação, ou após a reconstrução do núcleo de preenchimento (n=10). Após o armazenamento por 24 h, as amostras foram seccionadas e submetidas ao ensaio de cisalhamento por extrusão utilizando máquina de ensaio mecânico (EMIC DL 2000). Os dados foram analisados por ANOVA dois fatores (cimento resinoso x momento do corte do pino) e teste de Tukey (=0,05). O momento do corte do pino de fibra de vidro não afetou a resistência de união quando o RelyX Unicem foi utilizado. No entanto, o corte do pino imediatamente após a cimentação reduziu os valores de resistência de união quando o RelyX ARC foi utilizado. Em conclusão, o momento do corte do pino pode afetar a resistência de união ao canal radicular quando o cimento resinoso convencional for utilizado.

Does bonding to dentin reduce microleakage of composite restorations?

This study evaluated the effect of adhesive application only to enamel on the marginal microleakage of composite resin restorations performed with different adhesive systems. Standardized cylinder-shaped cavities were prepared on the buccal surface of eighty bovine incisors. Two etch-and-rinse (Adper Scotchbond Multi-purpose [3M ESPE, St. Paul, MN USA] and Adper Single Bond 2 [3M ESPE]) and two self-etching (Clearfil SE Bond [Kuraray, Osaka, Japan] and Adper Prompt [3M ESPE]) adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light-activation, the cavities were restored with composite resin. The samples were coated with two layers of nail polish, except an area of 1-mm wide around of the restoration, and immersed in a methylene blue solution. Afterwards, the specimens were ground in order to obtain powder which was immersed in absolute alcohol. The solutions were centrifuged and the supernatant was analyzed using an absorbance spectrophotometer. Linear regression was used to estimate the dye concentration. Data were analyzed using ANOVA and Tukey's tests (alpha = 0.05). The etch-and-rinse adhesives showed lower microleakage means compared to those of the self-etching adhesives. Adper Prompt presented higher microleakage means. There was no difference between the modes of application of the adhesive on the cavity for all adhesive systems, except for Clearfil SE Bond. This showed lower microleakage when applied to the whole cavity. Bonding to dentin may not reduce microleakage of composite restorations.

Uso de coroa em cerâmica pura associada a pino de fibra de vidro na reabilitação estética do sorriso: relato de caso / All ceramic crown associated to fiberglass post: a clinical case report

Restauração de dentes tratados endodonticamente constituidesafio permanente na odontologia, uma vez que aspectos biomecânicos,estéticos e complexidade de execução técnica podemresultar em insucesso com consequente perda do elemento dentário.Geralmente dentes tratados endodonticamente se encontramenfraquecidos devido à perda de estrutura dentária o queresulta em redução de resistência mecânica da dentina. Estesfatores resultando em maiores riscos de falhas biomecânicasquando comparados aos dentes com vitalidade pulpar. Este trabalhotem por objetivo apresentar procedimentos clínicos reabilitadorespara devolução de harmonia estética com ênfase emprocedimentos realizados em incisivo central superior com extensaperda de estrutura coronária e restauração em resina compostainsatisfatória. Foi empregada a associação de pino de fibrade vidro (Exacto, Ângelus) e resina composta para reconstruçãointerna seguido de coroa em cerâmica pura (In Ceram Alumina,Vita). São destacados os passos clínicos e breve revisão de aspectosbiomecânicos e estéticos desta alternativa reabilitadora.

Restoration of endodontically treated teeth is a challenge inoperative dentistry, since the biomechanical, aesthetic and complexityof the technique can result in failure with subsequenttooth loss. Generally endodontically treated teeth are weakeneddue to loss of tooth structure and reduce the mechanicalstrength of dentin. These factors result in a higher risk of biomechanicalfailure when compared to teeth with pulp vitality.This paper aims to present clinical rehabilitation procedures torecover the smile harmony with an emphasis on aesthetic proceduresperformed in the maxillary central incisor with extensiveloss of coronal tooth tissue and unsatisfactory compositeresin restoration. It was employed the combination of fiberglasspost (Exacto, Angelus) and coronal reconstruction with compositeresin followed by all ceramic alumina crown (In CeramAlumina, Vita). Highlights the clinical steps and brief review ofbiomechanical and aesthetic rehabilitation of this alternative aredescribed.

Cirurgia plástica periodontal para correção de sorriso gengival associada à restaurações em resina composta: relato de caso clínico / Periodontal plastic surgery associated with composite resin restorations: case report

O objetivo deste relato de caso clínico é descrever uma cirurgia periodontal para correção de sorriso gengival e ajuste cosmético associado à restaurações estéticas diretas em resina composta. Paciente do gênero feminino insatisfeita com seu sorriso apresentou ao exame clínico irregularidades no contorno gengival, coroas clínicas curtas nos dentes anteriores, presença de restaurações classe III esteticamente insatisfatórias e giroversão no canino. Foi realizada cirurgia de gengivectomia de bisel interno, proporcionando equilíbrio estético entre as estruturas faciais e dento gengivais. Após três meses da cirurgia a terapia cosmética foi realizada para corrigir a giroversão do canino, possibilitando o melhor alinhamento dental, e substituição das restaurações estéticas anteriores em resina composta. A interação entre a Periodontia e a Dentística mostrou-se essencial para viabilizar a previsível reabilitação estética e funcional, possibilitando atender as expectativas da paciente e proporcionar longevidade.

The aim of this case report is to describe a surgical procedure of increasing clinical crowns of anterior teeth and to adequate the smile line associated with direct cosmetic restorations. A female patient presented dissatisfaction with smile, regarding of gum line irregularity, short clinical crowns, unsatisfactory class III restorations and position alterations of canine. A modified Widman surgery with partial-thickness mucoperiosteal flap was done aiming to increase the clinical crowns of anterior teeth and to modify the smile line, providing a better balance between the facial structures and dental-gingival relation. After three months of surgery, cosmetic adjustment was made to correct the position of maxillary canine, improve the alignment and a replacement of the anterior restorations were performed. The interaction between Periodontology and Restorative Dentistry showed is essential for obtaining the favorable aesthetic rehabilitation and maintaining the functionality and periodontal health, which contributes for better longevity.

Influence of different post design and composition on stress distribution in maxillary central incisor: Finite element analysis.

BACKGROUND: Post design and material has very important effects on dentinal stress distribution since the post placement can create stresses that lead to root fracture. MATERIALS AND METHODS: In this study we use finite element analysis (FEA) to evaluate stress distribution on endodontically treated maxillary central incisors that have been restored with different prefabricated posts. Six models were generated from the image of anatomical plate: Four metallic posts (ParaPost XH, ParaPost XT, ParaPost XP, and Flexi-Flange) and one fiberglass post (ParaPost Fiber Lux). The sixth model was a control-a sound maxillary central incisor. We used CAD software and exported the models to ANSYS 9.0. All the materials and structures were considered elastic, isotropic, homogeneous, and linear except the fiberglass post which was considered orthotropic. The values for the mechanical properties were obtained by a review of the literature and the model was meshed with 8-node tetrahedral elements. A load of 2N was applied to the lingual surface at an angle of 135 degrees. RESULTS: The stress results were recorded by shear stress and von Mises criteria; it was observed that there was no difference for stress distribution among the titanium posts in the radicular portions and into posts. There was higher stress concentration on the coronary portion with the titanium posts than with the glass fiber post. It seems that the metallic posts' external configuration does not influence the stress distribution. CONCLUSION: Fiber posts show more homogeneous stress distribution than metallic posts. The post material seems to be more relevant for the stress distribution in endodontically treated teeth than the posts' external configuration.

Finite element analysis and bond strength of a glass post to intraradicular dentin: comparison between microtensile and push-out tests.

OBJECTIVE: This study tested the hypothesis that the stress distribution and bond strength of glass posts to intraradicular dentin is influenced by the mechanical testing methodology. METHODS: Thirty single rooted endodontically treated teeth were prepared for luting of tapered fiber-glass posts (Reforpost, Angelus, Londrina, PR, Brazil) with a conventional adhesive system and resin luting cement (Adper Scotchbond Multi-purpose, Rely X ARC, 3M ESPE, St. Paul, MN, USA). The teeth were randomly divided (n=10 per group) into micro-push-out (Mpo), hourglass- (Mh) and rectangular stick-shaped (Ms) microtensile testing groups before sectioning each root into five 1-mm-thick specimens. During specimen preparation for microTBS testing 46/50 stick and 4/50 hourglass specimens prematurely failed; therefore, the Ms group could not be included in the mechanical testing. The remaining specimens were tested at 0.5 mm/min until bond failure. Stress distribution within each specimen type for the three mechanical test methods was analyzed by finite element analysis (FEA). Qualitative analyses were carried out through Von Mises, XY and Sy criterion. RESULTS: Mpo and Mh had a mean microTBS of 11.89+/-6.55 and 14.98+/-12.72 MPa, respectively, which was not significantly different (p=0.1311). The push-out test demonstrated a more homogenous stress distribution by FEA and less variability in mechanical testing. SIGNIFICANCE: Therefore, the recommended testing method for determining the bond strength of glass posts to intraradicular dentin is by Mpo.