In Vitro Tensile Strength of Luting Cements on Metallic Substrate

The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm2. Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm2), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm2 and the zinc phosphate cement with 1.155 MPa/mm2. Glass ionomer cement (0.884 MPa/mm2) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied.

O objetivo deste estudo foi determinar a resistência à tração de coroas cimentadas em substrato metálico com quatro diferentes tipos de agentes cimentantes. Vinte molares humanos maxilares com diâmetros semelhantes foram selecionados e preparados para receberem núcleos metálicos fundidos (Cu-Al). Após cimentação e preparo, os núcleos foram mensurados e a área da porção coronária foi calculada. Os dentes foram divididos em quatro grupos baseados no agente cimentante utilizado para cimentar as coroas: cimento de fosfato de zinco; cimento de vidro ionômero; cimento resinoso Rely X; e cimento resinoso Panavia F. Os dentes com as coroas cimentadas foram submetidos a termociclagem e logo à prova de resistência à tração usando a máquina de ensaios universal com uma célula de carga de 200 kgf e uma velocidade de 0,5 mm/min. A carga necessária para deslocar as coroas foi registrada e convertida a MPa/mm2. Os dados foram submetidos ao análise de Kruskal-Wallis com um nível de significância de 1%. Panavia F mostrou uma retenção significativamente maior nos núcleos fundidos (3,067 MPa/mm2), quando comparados com os outros cimentos. Rely X mostrou um valor médio de retenção de 1,877 MPa/mm2 e o cimento de fosfato de zinco com 1,155 MPa/mm2. O cimento de vidro ionômero (0,884 MPa/mm2) exibiu o menor valor de resistência à tração. As coroas cimentadas com Panavia F nos pinos e núcleos metálicos fundidos apresentaram maior resistência à tração. O cimento de ionômero de vidro mostrou o menor valor de resistência à tração entre todos os cimentos estudados.

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.

Influencia de los materiales de cementación en la distribución de los esfuerzos en un incisivo central superior rehabilitado con poste: análisis de elementos finitos / Influence of cementation materials in the stress distribution of an upper central incisor restored with posts: a finite element analysis

Introducción: para mejorar la predicibilidad de las restauraciones dentales, cada día se presentan nuevos materiales de cementación con diferentes propiedades mecánicas y físicas. El propósito de este estudio fue evaluar y analizar la influencia de los materiales de cementación en la distribución de los esfuerzos en un incisivo central maxilar rehabilitado con un elemento de retención intrarradicularcolado y prefabricado usando el método de elementos finitos (MEF). Métodos: se modeló un incisivo central superior restaurado con tres elementos de retención intrarradicular (poste colado en metal base, poste prefabricado de titanio y de fibra de vidrio), cementados cada uno con un ionómero de vidrio resinomodificado, cemento resinoso y cemento autoadhesivo. Las variables incluidas en el modelado fueron elmódulo de elasticidad, la razón de Poisson para todos los componentes del modelo. Para cada modelo fueron calculados los esfuerzos von Mises, los esfuerzos máximos y mínimos principales y los esfuerzos máximos cortantes. Resultados: el análisis de elementos finitos indicó que el cemento influye en la distribución de los esfuerzos cuando el poste es más flexible como el caso del poste prefabricado de fibra de vidrio, ya que el poste y cemento reciben los esfuerzos en conjunto. Conclusiones: a medida que el módulo de elasticidad de los cementos es más alto, se aumenta el esfuerzo recibido en ellos, pero su influencia en el sistema, depende de otras variables como el tipo de poste usado.

Introduction: in order to improve predictability of dental restorations, new cement materials with different mechanical and physical properties are frequently developed. The purpose of this study was to evaluate and analyze the influence of cement materials in thedistribution of stresses in an upper central incisor restored with a cast intrarradicular retention element and two prefabricated elements using the finite element method (FEM). Methods: a modeled upper central incisor restored with three dowels (based metal cast post, titanium prefabricated post and fiber glass) and each one cemented with resin-modified glass ionomer luting cement, self-adhesive resin luting cement and dual cured adhesive resin. The variables included were modulus of elasticity and Poisson’s ratio for all the components of the model. Von Misses stresses, main maximum and main minimum as well as maximum shear stress were calculated for each model. Results: the finite element analysis indicated that the cement influences stress distribution when the post is more flexible as in the case of prefabricated fiberglass because both post and cement receive the stress altogether. Conclusions: as the modulus of elasticity of luting cement is higher, the stress received among them increases, but its influence in the system depends on other variables such as the type of post that was used.

Effect of temporary cements on the shear bond strength of luting cements

OBJECTIVE: The purpose of this study was to evaluate, by shear bond strength (SBS) testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods: Forty human teeth divided in two halves were assigned to 8 groups (n=10): I and V (no temporary cementation); II and VI: Ca(OH)2-based cement; III and VII: zinc oxide (ZO)-based cement; IV and VIII: ZO-eugenol (ZOE)-based cement. Final cementation was done with RelyX ARC cement (groups I to IV) and RelyX Unicem cement (groups V to VIII). Data were analyzed statistically by ANOVA and Tukey's test at 5 percent significance level. RESULTS: Means were (MPa): I - 3.80 (±1.481); II - 5.24 (±2.297); III - 6.98 (±1.885); IV - 6.54 (±1.459); V - 5.22 (±2.465); VI - 4.48 (±1.705); VII - 6.29 (±2.280); VIII - 2.47 (±2.076). Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII) showed statistically significant difference (p<0.001) only between Groups IV and VIII, in which ZOE-based cements were used. The use of either Ca(OH)2-based (Groups II and VI) or ZO-based (Groups III and VII) cements showed no statistically significant difference (p>0.05) for the different luting cements (RelyX TM ARC and RelyX TM Unicem). The groups that had no temporary cementation (Groups I and V) did not differ significantly from each other either (p>0.05). CONCLUSION: When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation.

Compatibility of self-etching dentin adhesives with resin luting cements / 대한치과보존학회지

This study was performed to investigate the compatibility between 4 dentin adhesives and 4 resin luting cements. Dentin adhesives used in this study were All-Bond 2 (Bisco Inc., Schaumbrug, IL, USA), Clearfil SE-Bond (Kuraray Medical Inc, Osaka, Japan), Prompt L-Pop (3M Dental Products, St. Paul, MN, USA), One-Up Bond F (Tokuyama corp., Tokyo, Japan). Resin luting cements used in this study were Choice (Bisco Inc., Schaumbrug, IL, USA), Panavia F (Kuraray Medical Inc, Osaka, Japan), RelyX ARC (3M Dental Products, St. Paul, MN, USA), Bistite II DC (Tokuyama corp., Tokyo, Japan). Combination of each dentin adhesive and corresponding resin cement was made to 16 experimental groups. Flat dentin surfaces was created on mid-coronal dentin of extracted mandibular third molars, then dentin surface was polished with 320-grit silicon carbide abrasive papers. Indirect resin composite block (Tescera, Bisco) was fabricated. Its surface for bonding to tooth was polished with silicon carbide abrasive papers. Each dentin adhesive was treated on tooth surface and resin composite overlay were luted with each resin cement. Each bonded specimen was poured in epoxy resin and sectioned occluso-gingivally into 1.0 mm thick slab, then further sectioned into 1.0 x 1.0 mm2 composite-dentin beams. Microtensile bond strength was tested at a crosshead speed of 1.0 mm/min. The data were analysed by one-way ANOVA and Duncan's multiple comparison tests. The results of this study were as follows; 2-step self-etching dentin adhesive which has additional bonding resin is more compatible than 1-step self-etching dentin adhesive.