Effect of immediate dentin sealing, bonding technique, and restorative material on the bond strength of indirect restorations / Efeito do selamento imediato da dentina, técnica de união e material restaurador na resistência de união de restaurações indiretas

Objective: The objective of this study was to evaluate the effect of immediate dentin sealing, bonding technique, and restorative material on the dentin bond strength of an indirect composite (Solidex) and a resin nanoceramic CAD/CAM block (LAVA Ultimate). Material and Methods: A total of 120 periodontally extracted human molar teeth were abraded horizontally and divided into two groups according to dentin sealing procedures (delayed dentin sealing [DDS] and immediate dentin sealing [IDS]). Next, all teeth were attached to a simulated pulpal pressure mechanism. The specimens were removed from the mechanism after a week. Teeth were subdivided into three groups based on the bonding technique and the type of cement used (Acid-etching + Single Bond Universal + RelyX Ultimate, Single Bond Universal + RelyX Ultimate, RelyX Unicem). Each subgroup was further divided into 2 subgroups according to the type of restorative material used (Solidex [n = 10], Lava Ultimate CAD/ CAM restorative material [n = 10]). Sixty cylindrical samples prepared using both the restorative materials were bonded to the tooth surface according to their group's bonding procedures. All specimens were embedded in chemically cured acrylic resin for shear bond strength test. The shear bond strength (SBS) of the specimens was determined by a universal testing machine with a headspeed of 0.5 mm/min. Results: Three-way ANOVA, independent-sample t test and post hoc Tukey comparison tests (α=0.05) were performed on all data. There were significant differences between the groups. It was found that IDS process significantly increased bond strength in all groups. When dentin bond strengths of tested luting cements were compared, the highest bond strength values were recorded in groups in which the specimens were luted with RelyX Ultimate cement using etch-and-rinse technique. The lowest bond strength values were obtained from groups that used RelyX Unicem as the luting cement. Conclusion: IDS improves bond strength of indirect restorations. Moreover, bonding techniques may have critical effects on the dentin bond strength of indirect restorative materials. The cements' specific affinity levels to both restorative materials and dentin could be considered as the reason of the situation.(AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito do selamento imediato da dentina, da técnica adesiva e do material restaurador na resistência de união à dentina de um compósito indireto (Solidex) e um bloco CAD / CAM de resina nanocerâmica (LAVA Ultimate). Material e Métodos: Um total de 120 dentes molares humanos extraídos por razões periodontais foram desgastados horizontalmente e divididos em dois grupos de acordo com os procedimentos de selamento dentinário (vedação tardia da dentina [DDS] e vedação imediata da dentina [IDS]). Em seguida, todos os dentes foram conectados a um equipamento de pressão pulpar simulada. As amostras foram removidas do equipamento após uma semana. Os dentes foram subdivididos em três grupos, com base na técnica de união e no tipo de cimento utilizado (ataque ácido + Single Bond Universal + RelyX Ultimate, Single Bond Universal + RelyX Ultimate, RelyX Unicem). Cada subgrupo foi então dividido em 2 subgrupos de acordo com o tipo de material restaurador utilizado (Solidex [n = 10], material restaurador Lava Ultimate CAD / CAM [n = 10]). Sessenta amostras cilíndricas preparadas com os dois materiais restauradores foram coladas na superfície do dente de acordo com os procedimentos de adesão do grupo. Todas as amostras foram embebidas em resina acrílica quimicamente ativada para o teste de resistência ao cisalhamento. A resistência de união ao cisalhamento (SBS) das amostras foi determinada por uma máquina de teste universal com uma velocidade de 0,5 mm / min. Resultados: ANOVA de três fatores, teste t de amostra independente e testes de comparação post hoc de Tukey (α = 0,05) foram realizados em todos os dados. Houve diferenças significativas entre os grupos. Verificou-se que o processo IDS aumentou significativamente a força de união em todos os grupos. Quando as forças de união da dentina dos cimentos testados foram comparadas, os valores mais altos de força de união foram registrados nos grupos em que as amostras foram cimentadas com cimento RelyX Ultimate usando a técnica "condicione e lave". Os menores valores de resistência de união foram obtidos de grupos que usaram como cimento o RelyX Unicem. Conclusão: O IDS melhora a força de união das restaurações indiretas. Além disso, as técnicas de união podem ter efeitos críticos na resistência da união à dentina de materiais restauradores indiretos. Os níveis de afinidade específicos dos cimentos para materiais restauradores e dentina podem ser considerados o motivo da situação.(AU)

Shear Bonding Strength of Three Cements Luted on Pediatric Zirconia Crowns and Dentin of Primary Teeth / 대한소아치과학회지

The aim of this study was to evaluate the shear bond strength of three luting cements and to identify the effect of thermocycling.Zirconia discs were made similar to the inner surface of a preformed pediatric zirconia crown (NuSmile® ZR crown: ZRCr). The similarity between the zirconia discs and the inner surface of a ZRCr was confirmed by scanning electron microscope. Three luting cements were Ketac™ Cem Permanent Glass Ionomer Luting Cement (KGI), RelyX™ Luting Plus Cement (RLP), RelyX™ Unicem Self-Adhesive Universal Resin Cement (RUR). Three luting cements were bonded according to the manufacturer's instructions for 60 zirconia discs and 60 dentin of primary teeth. Total of 120 specimens were divided into two subgroups: One was not aged, and the other was tested with 5500 thermocycling. Shear bond strength was measured using a universal testing machine, and the fracture patterns were observed with SEM.On the zirconia discs and the dentin of primary teeth, shear bond strength of RUR was higher than that of KGI and RLP, and there were statistically significant differences by cement type. The shear bond strength differences for RUR were not statistically significant depending on thermocycling.

The effect of continuous application of MDP-containing primer and luting resin cement on bond strength to tribochemical silica-coated Y-TZP

OBJECTIVES: This study investigated the effect of continuous application of 10-methacryloyloxydecyldihydrogen phosphate (MDP)-containing primer and luting resin cement on bond strength to tribochemical silica-coated yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). MATERIALS AND METHODS: Forty bovine teeth and Y-TZP specimens were prepared. The dentin specimens were embedded in molds, with one side of the dentin exposed for cementation with the zirconia specimen. The Y-TZP specimen was prepared in the form of a cylinder with a diameter of 3 mm and a height of 10 mm. The bonding surface of the Y-TZP specimen was sandblasted with silica-coated aluminium oxide particles. The forty tribochemical silica-coated Y-TZP specimens were cemented to the bovine dentin (4 groups; n = 10) with either an MDP-free primer or an MDP-containing primer and either an MDP-free resin cement or an MDP-containing resin cement. After a shear bond strength (SBS) test, the data were analyzed using 1-way analysis of variance and the Tukey test (α = 0.05). RESULTS: The group with MDP-free primer and resin cement showed significantly lower SBS values than the MDP-containing groups (p < 0.05). Among the MDP-containing groups, the group with MDP-containing primer and resin cement showed significantly higher SBS values than the other groups (p < 0.05). CONCLUSIONS: The combination of MDP-containing primer and luting cement following tribochemical silica coating to Y-TZP was the best choice among the alternatives tested in this study.

Comparative study of the radiopacity of resin cements used in aesthetic dentistry

PURPOSE: The aim of this study was to compare the radiopacity of 6 modern resin cements with that of human enamel and dentine using the Digora digital radiography system, to verify whether they meet the requirements of ANSI/ADA specification no. 27/1993 and the ISO 4049/2000 standard and assess whether their radiopacity is influenced by the thickness of the cement employed. MATERIALS AND METHODS: Three 3-thickness samples (0.5, 1 and 1.5 mm) were fabricated for each material. The individual cement samples were radiographed on the CCD sensor next to the aluminium wedge and the tooth samples. Five radiographs were made of each sample and therefore five readings of radiographic density were taken for each thickness of the materials. The radiopacity was measured in pixels using Digora 2.6 software. The calibration curve obtained from the mean values of each step of the wedge made it possible to obtain the equivalent in mm of aluminium for each mm of the luting material. RESULTS: With the exception of Variolink Veneer Medium Value 0, all the cements studied were more radiopaque than enamel and dentin (P<.05) and complied with the ISO and ANSI/ADA requirements (P<.001). The radiopacity of all the cements examined depended on their thickness: the thicker the material, the greater its radiopacity. CONCLUSION: All materials except Variolink Veneer Medium Value 0 yielded radiopacity values that complied with the recommendations of the ISO and ANSI/ADA. Variolink Veneer Medium Value 0 showed less radiopacity than enamel and dentin.

Restauración postendodóntica en conductos radiculares amplios / Postendodontic restoration in wide root canals

Gracias al auge que tiene la implantología en la actualidad y al aumento del porcentaje de éxitos de la misma, los clínicos ahora, antes que intentar prolongar la vida del órgano dental afectado en la cavidad oral, prefieren realizar una extracción. Siguiendo los cánones de la odontología conservadora, ponemos a consideración una técnica que puede ayudar, como última opción, a mantener dientes tratados endodónticamente, antes de llevar a cabo su extracción. Esta técnica ya ha sido propuesta y debidamente investigada por algunos autores. Esta propuesta se aplica a dientes con conductos radiculares amplios, los cuales se han debilitado por restauraciones deficientes, desmineralización de la dentina, por filtraciones en la corona y poste radicular o simplemente conductos amplios en pacientes de corta edad. Tenemos la firme convicción que no podremos garantizar la permanencia de un órgano dental en la cavidad oral, pero sí podemos intentar alargarle su permanencia en el alvéolo. Por eso damos a conocer la técnica de rellenar previamente el conducto con ionómero de vidrio de alta densidad. Este material dental tiene un módulo de elasticidad similar a la dentina, lo que aumenta su integridad y mejora la técnica al colocar un poste con menor cantidad de cemento o al emplear un poste demasiado amplio.

With the boom in implantology in today’s dentistry and its undeniable success, many clinicians now prefer to perform an extraction rather than extend the life of the tooth. According to the standards of conservative dentistry, we propose a technique that could be useful as a final option before resorting to an extraction, for teeth on which a root canal has been performed in the past. This type of treatment has been described and properly researched by several authors. It can be applied in wide root canals that have been weakened by poor restorations or demin-eralization of the dentin caused by a filtration through the crown, or simply in young patients with wide canals. Whilst we cannot guarantee that a tooth be preserved indefinitely, we do believe we can make it last longer. For this reason, we describe the technique that involves first filling the root canal with high-density glass ionomer —a dental material that has a modulus of elasticity similar to that of dentin—, which increases its integrity. This makes for an improved technique when posts are inserted as less luting cement is used and eliminates the need to use a wider post.

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 blotdried. 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.

1-Year clinical study of indirect resin composite restorations luted with a self-adhesive resin cement: effect of enamel etching

In vitro studies have recommended enamel-etching before luting indirect restorations with self-adhesive resin cement. However, there is no scientific proof that this procedure has any clinical relevance. Thus, the aim of this study was to evaluate the effect of enamel-etching on the marginal quality of indirect composite resin restorations (inlay/onlay) using the self-adhesive cement RelyX Unicem clicker. Forty-two posterior teeth were selected from 25 patients that presented one or two teeth with large restorations in need of replacement. All teeth were prepared by the same operator and impressed with polyvinylsiloxane material. The composite resin restorations were built over plaster casts using the incremental technique with a LED device for light-curing the increments. The inlays/onlays were cemented according to one of the following protocols: 1. Etched group (ETR) - selective enamel phosphoric-acid etching + RelyX Unicem clicker; 2. Non-etched group (NER) - RelyX Unicem clicker alone. Each surface was light-cured for 60 s. Recalls occurred after 1 week (baseline), 6 and 12 months when the teeth were evaluated according to previously established scores (modified USPHS criteria). The clinical analysis showed little or no visible changes in the marginal quality after 1 year, even though a probe could detect all the restorations margins. Statistical analysis (Fisher’s exact test, p<0.05) detected no differences between the groups after 12 months. No restorations failed and no secondary caries were found. Enamel acid etching had no clinical relevance on the marginal quality of indirect composite resin restorations luted with RelyX Unicem clicker after 1 year of follow up.

Estudos in vitro têm recomendado condicionamento ácido do esmalte antes da cimentação de restaurações indiretas com cimento resinoso autoadesivo. Entretanto, não há nenhuma prova científica de que este procedimento tenha relevância clínica. Assim, o objetivo deste estudo foi avaliar o efeito do condicionamento ácido do esmalte na qualidade marginal de restaurações indiretas de resina composta (inlay/onlay) usando o cimento autoadesivo RelyX Unicem clicker. Quarenta e dois dentes posteriores foram selecionados de 25 pacientes com 1 ou 2 restaurações amplas com necessidade de substituição. Todos os dentes foram preparados pelo mesmo operador e impressos com material à base de polivilsiloxano. As restaurações de resina composta foram construídas sobre troquel de gesso usando a técnica de colocação em camadas e polimerizadas usando aparelho de luz emitida por diodo (LED). Osinlays/onlays foram cimentados de acordo com um dos protocolos: 1. Grupo condicionado (ETR)- condicionamento seletivo do esmalte com ácido fosfórico + cimentação com RelyX Unicem clicker; 2. Grupo não condicionado (NER)- cimentação com RelyX Unicem clicker somente. Cada superfície foi fotoativada por 60 s. Os retornos para acompanhamento foram feitos após 1 semana (baseline), 6 e 12 meses onde os dentes foram avaliados de acordo com critérios previamente estabelecidos (USPHS Modificado). A análise clínica mostrou pouca ou nenhuma alteração visível na qualidade marginal após 1 ano, porém uma sonda clínica pode detectar todas as margens restauradoras. A análise estatística (Teste exato de Fisher, p<0,05) não detectou diferença entre os grupos após 12 meses. Nenhuma restauração falhou e nenhuma cárie secundária foi encontrada. O condicionamento ácido do esmalte não teve relevância clínica na qualidade marginal de restaurações indiretas de resina composta cimentadas com RelyX Unicem clicker após 1 ano de acompanhamento.

An evaluation of retention and marginal seating of Ni-Cr alloy cast restorations using three different luting cements: An in vitro study.

Context: Clinical and laboratory studies regarding performance of recently introduced luting cements: Adhesive resin cement and resin-modified glass ionomer cement (GIC), are limited. Aims: To compare the retention and marginal seating of Ni-Cr alloy restorations using newer luting cements: Resin-modified GIC and adhesive resin cement with those of the oldest cement, zinc phosphate. Materials and Methods: Thirty maxillary premolars of similar sizes were prepared to receive cast metal copings. Copings were placed on the prepared teeth and the marginal opening was examined using a Nikon Measuroscope. The specimens were randomly assigned to three groups. Group I castings were luted with zinc phosphate, Group II castings luted with resin-modified GIC, and Group III castings luted with adhesive resin cement. After cementation marginal seating was measured. Tensile loads required to dislodge the crowns were obtained using MTS machine. Statistical Analysis Used: Tukey's test, Analysis of Variance (ANOVA). Results: For zinc phosphate cement, mean marginal seating was 31 microns. Mean retentive strength was 287 Newtons. For resin-modified GIC, mean marginal seating was 29.6 microns. Mean retentive strength was 610 Newtons. For adhesive resin cement, mean marginal seating was 49 microns. Mean retentive strength was 613 Newtons. Conclusions: Marginal seating of adhesive resin cement was significantly greater than that of zinc phosphate and resin-modified GIC. Retentive strength of adhesive resin cement and resin-modified GIC was significantly greater than that of zinc phosphate There was no significant difference of retentive strength between adhesive resin cement and resin-modified GIC.

Water interaction with dental luting cements by means of sorption and solubility / Interação da água com cimentos dentais de acordo com a sorção e solubilidade

Water contributes to the setting reaction of self-adhesive luting cements, however, it can also accelerate their degradation. Objectives: The aim of this study was to compare a self-adhesive resin luting cement to other resin-based and glass-ionomer luting materials with regards to water sorption (WS) and solubility (WSB). The tested null hypothesis was that there is no difference in respect to these properties among the materials. Material and methods: Eight specimens from each group (15 mm x 0.5 mm) were prepared from self-adhesive luting cements Biscem (BC) and RelyX Unicem (R), dual-cure cements Bifix (BF), Allcem (A) and Enforce (E), chemical-cure cements C&B (CB) and Cement Post (CP) and a glass-ionomer luting cement Meron C (M) as the control group. The dual-cure products were light-cured beneath an IPS Empress Esthetic ceramic disk (20 mm x 1.5 mm) and for the chemical reaction materials, a 15 min-interval was respected for removal from the mould. The WS and WSB were respectively calculated as (m2-m3/V) and (m1-m3/V). Mass values of m1, m2 and m3 were determined by cycles of desiccation, water-immersion and a new desiccation. For each property, the data was analyzed by one-criteria ANOVA and Tukey tests (p < 0.05). Results: The glass-ionomer cement presented the highest WS, followed by the self-adhesive luting cements. Other resin cements were less susceptible to WS. No materials differed from each other when the WSB was considered, except for the M, which presented the lowest WSB. Conclusions: Self-adhesive luting cements were more prone to WS since water is essential to their setting reaction. However, their WSB was similar to the other resin-based cements.

A água contribui para a reação de presa dos cimentos auto adesivos, entretanto pode acelerar a sua degradação. Objetivos: O objetivo deste estudo foi comparar cimentos auto adesivos a outros cimentos resinosos e material ionomérico em relação à sorção de água (WS) e solubilidade (WSB). A hipótese nula foi de que não há diferença em relação a essas propriedades entre os materiais. Material e métodos: Oito espécimes de cada grupo (15 mm x 0,5 mm) foram preparados dos cimentos auto adesivos Biscem (BC) e RelyX Unicem (R), cimentos duais Bifix (BF), Allcem (A) e Enforce (E), cimentos químicos C&B (CB) e Cement Post (CP) e um cimento ionomérico Meron C (M) como grupo controle. Os produtos duais foram fotoativados sob um disco cerâmico de IPS Empress Esthetic (20 mm x 1,5 mm) e para os materiais de reação química, um intervalo de 15 min foi respeitado para a remoção do molde. A WS e WSB foram respectivamente calculadas como (m2-m3/V) e (m1-m3/V). Valores de massa m1, m2 and m3 foram determinadas pelos ciclos de dessecação, imersão em água e nova dessecação. Para cada propriedade, os dados foram analisados pelos testes de ANOVA a um critério e Tukey (p < 0.05). Resultados: O cimento ionomérico apresentou a maior WS, seguido dos cimentos auto adesivos. Os demais cimentos resinosos foram menos suscetíveis a WS. Nenhum material diferiu do outro quanto a WSB foi considerada, exceto por M, que apresentou a menor WSB. Conclusões: Cimentos auto adesivos foram mais suscetíveis a WS, uma vez que a água é essencial para sua reação de presa. Entretanto, seu WSB foi similar aos demais cimentos resinosos.

Influence of ceramic primers on microshear bond strength between resin cements and zirconia-based ceramic

This study evaluated the effect of a coupling agent ceramic primer (CP) on the microshear bond strength (ìsbs) between luting cements and zirconia-based ceramic. Methods: Zirconia discs (Cercon) were made and finished with silicon carbide paper and submitted to air abrasion using 50 μm aluminum oxide particles (Al2O3) under 4 bar pressure. Zirconia disks were randomly assigned to four groups (n=10): (G1) ResiCem luting cement + Porcelain Primer, (G2) ResiCemluting cement only, (G3) Clearfil Esthetic Cement + Clearfil Ceramic Primer and (G4) Clearfil Esthetic Cement only. The luting cements were prepared according to manufacturers’ recommendations and inserted in an elastomeric mold positioned onto a zirconia disc. Each specimen was photoactivated by 20 s. The specimens were stored at 100% relative humidity and 37ºC for 24 h. The ìsbs test was performed using universal testing machine at a crosshead speed of 0.5 mm/min. An optical microscope was used to analyze the failure modes and illustrative images were captured with a scanning electron microscope. The ìsbs data were analyzed by two-way ANOVA (p<0.05). Results: No significant difference was found among the four groups G1 (17.4±6.8), G2 (17.1±5.5), G3 (15.6±5.5) and G4 (14.2±3.5), all of which showed 100% of adhesive failures. Conclusions: CP showed no increase in the ìsbs between zirconia-based ceramic and resin luting cements.

Efeito da técnica úmida simplificada de adesão com etanol na cimentação intraradicular de pinos de fibra / Push-out bond strength and SEM evaluation of new bonding approach into the root canal

Este estudo avaliou a resistência ao deslocamento vertical push-out de pinos de fibra de vidro cimentados à dentina intra-radicular utilizando uma resina fluida padrão como agente cimentante em combinação com um adesivo dentinário experimental e um adesivo disponível comercialmente. 20 pré-molares unirradiculares humanos foram previamente extraídos e tratados endodonticamente. Os espécimes foram divididos em quatro estratégias de união a dentina: Grupo 1 com adesivo experimental com etanol na proporção em volume 1:1 (resina/etanol) e Grupo 2 com adesivo experimental com etanol na proporção em volume 1:2(resina/etanol); adesivos experimentais aplicados de acordo com a técnica úmida de adesão simplificada com etanol, Grupo 3: One-Step Plus aplicado de acordo com a técnica úmida de adesão simplificada com etanol; Grupo 4: One-Step Plus aplicado seguindo as instruções do fabricante. Os espécimes foram seccionados em fatias de 1 mm de espessura e apos o teste push-out foi realizado. Espécimes representativos foram selecionados para exame ultra-estrutural. Não houve diferença estatística na resistência ao deslocamento push-out entre as estratégias testadas de adesão (p> 0,05). O padrão predominante de fratura foi entre os pinos de fibra e o agente cimentante. A partir deste estudo devemos considerar como promissora a técnica com etanol utilizada na cimentação de pinos no canal radicular devido aos possíveis benefícios das resinas altamente hidrófobas. Mais estudos são necessários para validar o uso da técnica úmida de adesão simplificada com etanol quando cimentados pinos de fibra.

This study evaluated the push-out bond strength of glass fiber posts adhesively bonded to intraradicular dentin using a standard unfilled resin as luting agent in combination with an experimental and a commercially available adhesive. Twenty extracted single-rooted human teeth were endodontically treated. Specimens were assigned to 4 dentin bonding strategies: Group 1 (co-monomers to ethanol on ratio 1:1) and Group 2 (co-monomers to ethanol on ratio 1:2): Experimental adhesives applied in accordance with the simplified ethanol-wet bonding technique; Group 3: One-Step Plus (OSP) applied in accordance with the simplified ethanol-wet bonding technique; Group 4: OSP applied following manufacturers instructions. Bonded specimens were sectioned in 1-mm-thick slices and the push-out test was performed. Representative specimens were selected for ultrastructural examination. No statistical differences in push-out bond strength were found among the tested bonding strategies (p>0.05). The major failure pattern was between the post and the luting cement. From this study the ethanol technique should be considered as a promising approach in the luting of fiber posts into the root canal due to the possible benefits of highly hydrophobic resins. Further studies are needed to validate the use of the ethanol-wet bonding technique when luting a fiber post.

A comparison of preliminary bond strength between oxide ceramics and three resin luting cements / 实用口腔医学杂志

Objective:To compare the shear bond strength between oxide ceramics and three resin cements. Methods: Blocks of zirconium dioxide and aluminium sesquioxide ceramics were treated with sandblasting and bonded with three luting cements respectively. After preserved in 37 ℃ water for 24 h, the shear bond strengths of these specimens were tested and the data were analyzed by SAS9.12 software package. Results: There were significant differences among alumina ceramics which manifested that shear bond strength of Superbond C&B was the highest (37.60±2.06) MPa. However, in zirconium dioxide groups, RelyX~(TM) Unicem showed the lowest bond strength(13.29±3.05) MPa,but there was no difference between Superbond C&B and Panavia~(TM) F. Conclusion: Both Superbond C&B and Panavia~(TM) F have reliable shear bond strength with oxide ceramics, while RelyX~(TM) Unicem is not so perfect.

Curing reaction of the light cured flowable composite resins through the endodontic translucent fiber post / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the efficacy and substitute possibility of a newly developed flowable composite resins as a luting cement for translucent fiber post. MATERIAL AND METHOD: Two kinds of 12 mm translucent fiber post (D.T. Light-Post (Bisco, USA) and FRC Postec (Ivoclar vivadent, Liechtenstein)) was inserted into the teflon mold (7 mm diameter, 9 mm long) and Filtek-Flow (3M ESPE, USA), a light activated flowable composite resin, was polymerized for 60 seconds through the post. Also, the post was cut from the tip to 9 mm, 6 mm, 3 mm, and Filtek-Flow was light cured according to each length. For comparison, 60 seconds light-cured and 24 hours self-cured two dual cured resin cement (Duo-cement (Bisco, USA) and 2 Panavia-F (Kuraray, Japan)) samples were prepared as control group. Also cavities (1 mm in width, 1 mm in depth, and 12 mm in length) were prepared using acrylic plate and aluminum bar, and flowable composite resin was filled and light cured by the diffused light from the fiber post's side wall. The degree of polymerization was measured according to the distance from curing light using Vickers' hardness test. RESULT: Within the limitation of this study, the following conclusions were drawn: 1. Vickers'hardness of light cured dual cured resin cement and flowable composite resin decreased from Panavia-F, Filtek-Flow, and Duo-cement accordingly (p<0.05). In the dual curing resin cement, light curing performed group showed higher surface hardness value than self cured only group (p<0.05). 2. Surface hardness ratio (light cured through fiber post /directly light cured) of D.T. Light-Post using Filtek-Flow showed about 70% in the 6 mm deep and about 50% in the 12 mm deep. FRC Postec showed only 40% of surface hardness ratio. 3. Surface hardness ratio by diffused light from the post's side wall showed about 50% at 6 mm and 9 mm deep, and about 40% at 12 mm deep in D.T. Light-Post. However, FRC Postec showed about 40% at 6 mm deep, and almost no polymerization in 9 mm and 12 mm deep.

Curing reaction of the light cured flowable composite resins through the endodontic translucent fiber post / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the efficacy and substitute possibility of a newly developed flowable composite resins as a luting cement for translucent fiber post. MATERIAL AND METHOD: Two kinds of 12 mm translucent fiber post (D.T. Light-Post (Bisco, USA) and FRC Postec (Ivoclar vivadent, Liechtenstein)) was inserted into the teflon mold (7 mm diameter, 9 mm long) and Filtek-Flow (3M ESPE, USA), a light activated flowable composite resin, was polymerized for 60 seconds through the post. Also, the post was cut from the tip to 9 mm, 6 mm, 3 mm, and Filtek-Flow was light cured according to each length. For comparison, 60 seconds light-cured and 24 hours self-cured two dual cured resin cement (Duo-cement (Bisco, USA) and 2 Panavia-F (Kuraray, Japan)) samples were prepared as control group. Also cavities (1 mm in width, 1 mm in depth, and 12 mm in length) were prepared using acrylic plate and aluminum bar, and flowable composite resin was filled and light cured by the diffused light from the fiber post's side wall. The degree of polymerization was measured according to the distance from curing light using Vickers' hardness test. RESULT: Within the limitation of this study, the following conclusions were drawn: 1. Vickers'hardness of light cured dual cured resin cement and flowable composite resin decreased from Panavia-F, Filtek-Flow, and Duo-cement accordingly (p<0.05). In the dual curing resin cement, light curing performed group showed higher surface hardness value than self cured only group (p<0.05). 2. Surface hardness ratio (light cured through fiber post /directly light cured) of D.T. Light-Post using Filtek-Flow showed about 70% in the 6 mm deep and about 50% in the 12 mm deep. FRC Postec showed only 40% of surface hardness ratio. 3. Surface hardness ratio by diffused light from the post's side wall showed about 50% at 6 mm and 9 mm deep, and about 40% at 12 mm deep in D.T. Light-Post. However, FRC Postec showed about 40% at 6 mm deep, and almost no polymerization in 9 mm and 12 mm deep.

In vitro study of the tensile bond strength of cement-eetained single implant prosthesis by the various provisional luting cements and the surface treatment of abutments / 대한치과보철학회지

The main disadvantage of cement-retained implant restorations is their difficulty in retriev-ability. Advocates of cemented implant restorations frequently state that retrievability of the restoration can be maintained if a provisional cement is used. The purpose of this study was to find the optimal properties of provisional luting cements and the surface treatment of abutments in single implant abutment system. 30 prefabricated implant abutments, height 8mm, diameter 6mm, 3-degree taper per side, with light chamfer margins were obtained. Three commercially available provisional luting agents which were all zinc oxide eugenol type ; Cavitec, TempBond and TempBond NE were eval-uated. No cement served as the control. TempBond along with vaseline, a kind of petrolatum(2:1 ratio) was also evaluated. Ten out of thirty abutments were randomly selected and abutment surfaces were sandblasted with 50 mu m aluminum oxide. Another ten abutments were sandblasted with 250 mu m aluminum oxide. A vertical groove, 1 mm deep and 5mm long was cut in each twenty abutments. Ten of them were sandblasted with 50 mu m aluminum oxide. The full coverage casting crowns were cemented to the abutments with the designat-ed provisional luting agent. Specimens were stored in distilled water at 37 degrees C for 24 hours. Each specimen was attached to a universal testing machine. A crosshead speed of 0.5mm/min was used to apply a tensile force to each specimen. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Tensile bond strength of provisional luting cements in no surface treatment decreased with the sequence of TempBond NE, TempBond, Cavitec, TempBond with vaseline, no cement. 2. Tensile bond strength more increased by surface treatment. Sandblasting with 250 mumaluminum oxide exhibited the highest tensile bond strength in the abutment cemented with TempBond NE and sandblasting with 50 mu m aluminum oxide exhibited the highest tensile bond strength in cemented with TempBond. 3. In the aspect of a groove formation, tensile bond strength significantly increased in TempBond with vaseline only and the others had no significant effect on tensile bond strength.

The Effect Of Temporary Cement And Desensitizer On The Bond Strength Of Luting Cements / 대한치과보철학회지

This study investigated the effect of temporary cement and desensitizer on the bond strength of luting cements. Total 96 dentin specimens were divided into two groups with and without temporary cementation. For temporary cement-treated group, specimens were cemented with Temp-bond(R) and all specimens were stored in distilled water at 37 celsius degrees for 7 days. Each group was further divided into 3 subgroups with Gluma(R), One-step(R) application and without desensitizer. After desensitizer application, Ni-Cr specimens were luted to dentin surface with Panavia-F(R) and Vitremer(R). Specimens were placed in distilled water at 37 celsius degrees for 24 hours and shear bond strength between metal and dentin was measured by a universal testing machine. The results were as follows: 1. In Panavia-F(R) cemented groups, the combination of One-step(R) without temporary cement showed the greatest strength. Among the desensitizer types, One-step(R) showed the highest bond strength, followed by No-desensitizer, Gluma(R). 2. In Vitremer(R) cemented groups, the combination of no temporary cement and without desensitizer showed the greatest bond strength. Among the desensitizer types, No-desensitizer group showed the highest bond strength. 3. The use of Gluma(R) significantly reduced the shear bond strength in Panavia-F(R) and Vitremer(R) groups. 4. All temporary cement-treated groups showed a significant lower shear bond strength than without temporary cement groups. 5. Desensitizer application significantly influenced the bond strength of the resin cement and resin modified glass ionomer cement.

THE EFFECT OF CYCLIC LOADING ON THE RETENTIVE STRENGTH OF FULL VENEER CROWNS / 대한치과보철학회지

Dislodgement of a crown or extension bridge and the loosening of a retainer of a bridge is a serious clinical problem in fixed restoration. Generally these problems are considered to be associated with deformation of the restoration. During biting, the restoration is subjected to complex forces and deforms considerably within the limit of its elasticity. Deformation of the restoration under the occlusal force induces excessive stress in the cement film, which then leads to the cement fracture. Such a fracture may eventually cause loss of the restoration. Because most of the past retention tests for full veneer crown were done without fatigue loading, they were not exactly simulating intraoral environment. And the purpose of this study was to evaluate the effect of cyclic cantilever loading on the retentive strength of full veneer crowns depending on different type of cements and taper of prepared abutment. Steel dies with 8degrees or 16degrees convergence angle were fabricated through milling and crowns with the same method. These dies and crowns were divided into 8 groups. Group 1: 16degrees taper die, cementation with zinc phosphate cement, without loading Group 2: 16'taper die, cementation with zinc phosphate cement, with loading Group 3: 8degrees taper die, cementation with zinc phosphate cement, without loading Group 4: 8degrees taper die, cementation with zinc phosphate cement, with loading Group 5: 16degrees taper die, cementation with Panavia 21, without loading Group 6: 16degrees taper die, cementation with Panavia 21, with loading Group 7: 8degrees taper die, cementation with Panavia 21, without loading Group 8: 8degrees taper die, cementation with Panavia 21, with loading After checking the fit of die and crown, the luting surface of dies and inner surface of crowns were air-abraded for 10 seconds. The crowns were cemented to the dies, with cements mixed ac cording to the manufacturer' s recommendations. A static load of 5 kg was then applied for 10 min utes with static loading device. Twenty-four hours later, group 1,3,5,7 were only thermocycled, group 2,4,6,8 were subjected to cyclic loading after thermocycling. Retentive tests were performed on the Instron machine. From, the finding of this study, the following conclusions were obtained. 1. Panavia 21 showed significantly higher retentive strength than zinc phosphate cement for all groups(p0.05). 3. Cyclic loading significantly decreased the retentive strength for all groups (p<0.05) . 4. For zinc phosphate cement, there was 35% reduction of the retentive strength after loading in the 16degrees taper die, 25% in the 8degrees taper die, and for Panavia 21, 21% in the 16degrees taper die, 18% in the 8degrees taper die.