Do preheated composite resin or adhesive resin layer strengthen the feldspar ceramic?

STATEMENT OF PROBLEM: Preheated composite resin and adhesive coating have been recommended as luting agents for ceramic veneers; however, information about the mechanical behavior of feldspathic porcelain veneers after using these methods is still limited. PURPOSE: The purpose of this in vitro study was to evaluate the influence of the use of preheated composite resin or an adhesive resin layer on the strengthening of a feldspathic porcelain. MATERIAL AND METHODS: Feldspathic porcelain disks were fabricated (N=210), etched (10% hydrofluoric acid for 90 seconds), and bonded according to resin-based luting agents (30 per group) for the biaxial flexural strength tests: photopolymerized resin cement, flowable composite resin, preheated composite resin, with or without previous adhesive coating. Characteristic strength and Weibull modulus were calculated. The viscosity of the luting agents was measured by using isothermal analyses. Finite element analysis simulated the flexural test. Fractographic and bonded interfaces were observed. RESULTS: The use of preheated composite resin led to the lowest stress levels in the feldspathic porcelain veneers. However, it did not increase the ceramic strengthening compared with other luting agents, as higher values were observed with flowable composite resin (P<.05). The use of an adhesive resin layer had no significant effect on ceramic strengthening when associated with preheated composite resin or resin cement (P>.05). Preheated composite resin presented the highest viscosity and led to incomplete filling of the porcelain surface irregularities. Failures originated on the ceramic surface subjected to tensile stress and were typically associated with pores at the ceramic-luting agent interface. CONCLUSIONS: The use of preheated composite resin or an adhesive resin layer did not have a positive effect on strengthening feldspathic porcelain.

Influência de diferentes silanos na resistência de união entre cerâmica de dissilicato de lítio e cimento resinoso / Influence of different silanes on the bond strength between lithium disilicate and resin cement

Objetivo: O objetivo do estudo foi avaliar o uso de diferentes marcas de silano na resistência de união entre a cerâmica de dissilicato de lítio e o cimento resinoso. A hipótese nula avaliada foi que as diferentes marcas de silanos apresentariam similar resistência de união. Métodos: Foram confeccionados 80 discos de dissilicato de lítio (IPS E.max CAD) com (12 mm x 1 mm). Após a cristalização, foram incluídos em tubos de PVC com resina acrílica e polidos com lixas de carbeto de silício, sob irrigação com água. Após aplicação de ácido hidrofluorídrico 10%, foram lavados e secos e divididos aleatoriamente em 4 grupos para aplicação do silano (n=20). S-Y: Yller; S-M: Monobond N; S-U: Ultradent; S-DS: Dentsply Sirona. Uma matriz de silicone com 4 orifícios foi confecionada e preenchida posteriormente com o cimento resinoso (Multilink N) para realização do teste de microcilhamento (EMIC) e os dados foram avaliados pelo teste one-way ANOVA. Resultados: Análise de variância mostrou que não houveram diferenças estatísticas nos valores médios entre os grupos de tratamento (p=0,404). A média e desvio padrão (DP) da resistência de união (MPa) nos grupos foram: S-Y: 26,9 (6,3); S-M: 28,3 (5,8); S-U: 29,0 (8,0); S-DS: 31,8 (11,0). Conclusões: As diferentes marcas de silano avaliadas apresentaram resistência de união similar entre si. Porém, a aplicação de silano é fundamental para obter melhorias na resistência de união(AU)

Objective: To evaluate the use of different brands of silane in the bond strength between lithium disilicate and resin cement. The null hypothesis evaluated was that the different brands of silanes would present similar bond strength. Methods: 80 lithium disilicate discs (IPS E.max CAD) were made with 12 mm in diameter x 1 mm in thickness. After crystallization, they were included in PVC tubes with acrylic resin and polished with silicon carbide sandpaper, under irrigation with water, creating a smooth and flat surface and randomly divided into 4 groups (n = 20). G1: Yller; G2: Monobond N; G3: Ultradent; G4: Dentsply Sirona. The samples were stored for 24h in distilled water for subsequent microcutting testing. One-way analysis of variance was used to obtain the results. Results: Analysis of variance showed that there were no statistical differences in the mean values between the treatment groups (p = 0.404). The mean and standard deviation (SD) of the bond strength (MPa) in the groups were: G1: 26.9 (6.3); G2: 28.3 (5.8); G3: 29.0 (8.0); G4: 31.8 (11.0). Conclusions: The different brands of silane evaluated showed similar bond strength. However, application of silane is essential to obtain improvements in bond strength(AU)

Novas perspectivas para reabilitação de dentes tratados endodonticamente / Novel perspectives for the rehabilitation of endodontically treated teeth

Vários fatores podem influenciar o desempenho clínico de dentes com tratamento endodôntico (DTE). Além disso diversas são as opções restauradoras indicadas em respeito a este cenário, em especial com o notório avanço de novas técnicas e tecnologias para uso clínico. Dentre estas corriqueiramente envolvem-se o uso de restaurações diretas (confeccionadas com resina composta), pinos metálicos ou de fibra de vidro, pinos pré-fabricados ou fresados, assim como restaurações indiretas compostas de coroas cerâmicas, inlays, onlays ou endocrowns; sempre com o foco na reabilitação funcional e estética do caso em tela. Neste trabalho, através de uma revisão narrativa, foram expostos conceitos relativos às modalidades restauradores que se advêm do uso de novas tecnologias na reabilitação de dentes tratados endodonticamente(AU)

Several factors may influence the clinical performance of endodontically treated teeth (ETT). In addition, there are several restorative options indicated regarding this scenario, especially with the notable advance of new techniques and technologies for clinical use. These routinely involve the use of direct restorations (made of composite resin), metal or fiberglass posts, prefabricated or milled posts, as also indirect restorations composed of ceramic crowns, inlays, onlays or endocrown; always focusing on functional and aesthetic rehabilitation of the case in hand. In this study, through a narrative review, concepts related to the restorative modalities that were introduced with the use of new technologies in the rehabilitation of endodontically treated teeth were discussed(AU)

Desenvolvimento de instrumental para a padronização do volume e da forma dos incrementos de resina composta direta e relato de caso clínico / Development of instruments for the standardization of volume and shape of direct composite resin increments and clinical case report

Objetivo: O presente trabalho teve por objetivo desenvolver um protótipo de instrumental clínico que possibilita a padronização do volume e forma da massa de resina composta para o uso em procedimentos restauradores direto, além de relato de caso demonstrando a aplicabilidade do protótipo. Para isso, foi selecionada uma empresa produtora de instrumentos odontológicos e ativa no mercado nacional com registro na ANVISA. Tendo como base um calcador de Holemback número 6, esse, foi reconfigurado geometricamente afim de atingir os requisitos necessários para o desenho pretendido. Após a etapa de desenvolvimento, esse novo instrumento foi utilizado para o relato de um caso clínico de restauração direta de resina composta envolvendo esmalte e dentina das superfícies ocluso-distal do dente 15 e oclusal do dente 16. Os tecidos dentais foram hibridizados pela técnica adesiva associada de condicionamento seletivo do esmalte com ácido fosfórico e aplicação de sistema adesivo auto-condicionate (Clearfil SE Bond, Kuraray, Japão) em esmalte e dentina. A restauração foi realizada com a resina composta Z350 XT (3M ESPE, USA) nas cores A1 e A2B. Conclusão: A utilização do protótipo de instrumental auxilia na execução de restaurações direta de resina composta com o favorecimento ao controle das tensões geradas pela contração de polimerização e poderá ter papel importante no treinamento restaurador dos profissionais(AU)

Objective: The objective of this work was to develop a prototype of clinical instruments that allows the standardization of the volume and shape of the composite resin mass for use in direct restorative procedures, besides a case report demonstrating the applicability of the prototype. For this, a company was selected to produce dental instruments and active in the national market with ANVISA registration. Based on a Holemback number 6 presser foot, it was geometrically reconfigured to meet the requirements for the intended design. After the development stage, this new instrument was used to report a clinical case of direct restoration of composite resin involving enamel and dentin of the occlusal-distal surfaces of the tooth 15 and occlusal of the tooth 16. The dental tissues were hybridized by the adhesive technique associated with the selective conditioning of the enamel with phosphoric acid and the application of auto-conditioning adhesive system (Clearfil SE Bond, Kuraray, Japan) in enamel and dentin. The restoration was performed with the composite resin Z350 XT (3M ESPE, USA) in colors A1 and A2B. Conclusion: The use of the prototype of auxiliary instruments in the execution of direct restorations of composite resin with the favoring to control the tensions generated by the polymerization contraction and may play an important role in the restorative training of professional(AU)

Patients' perception about the outcomes of prosthetic treatment in Southern Brazil - a cross sectional study

Aim: this study assessed the patients' perception of the outcomes of prosthetic treatment in a University of Southern Brazil. Methods: patients seeking for prosthetic treatment were invited to answer a questionnaire with 41 items about the potential risks, benefits, and consequences of no treatment. Answers were obtained according to a five-item Likert-scale varying from 1 (completely disagree) to 5 (completely agree). Sociodemographic data was included in the comparison. Mann-Whitney or Kruskal-Wallis (95%) compared data depending on the variable. Results: two-hundred twenty-five patients answered the questionnaire. Median age of participants was 45-54 years. The potential benefits were similar among participants irrespective of the variable adopted. The perception of risks was significant influenced by variables gender, age, education level, type of edentulous space, prior treatment with prosthodontics, type of prosthodontics, and prosthodontics usage in years. Consequences of no treatment were affected by age, prior treatment with prosthodontics, and prosthodontics usage in years. Conclusions: the study showed the fundamental importance of correct elucidation about the potential risks (negative perception) in the initial appointment for the studied population. Elucidation about the consequences of no treatment are relevant because some differences were seen into the variables. Prosthodontics patients from the city of Passo Fundo seem well informed about the benefits of the prosthetic treatment, besides the significant influence of some sociodemographic and prosthetic conditions

Collagen vs expanded polytetrafluorethylene membranes during guided-bone regeneration simultaneous with implant placement: a systematic review / Membranas de colágeno vs politetrafluoretileno expandido para regeneração óssea guiada simultânea à colocação de implante: uma revisão sistemática

Purpose: This systematic review evaluated the influence of the membrane type (resorbable collagen or non-resorbable expanded polytetrafluorethylene; e-PTFE) on the guidedbone regeneration associated to implant placement. Methods: Any type of clinical study or literature review was searched at MEDLINE/PubMed and Cochrane databases. Two independent reviewers screened titles/abstracts of articles and the full-text of potentially eligible studies. When data was available, pairwise meta-analysis was performed using random statistical model. Results: Nine studies met the inclusion criteria, considering 685 implants in 360 patients. Vertical bone regeneration did not differ with the use of the two membranes in 8 of the 9 studies included. Meta-analysis did not show either greater vertical bone gain or vertical bone loss after regeneration with any of the membranes. The results have shown a tendency of higher bone gain in horizontal guided-bone regeneration with nonresorbable e-PTFE membranes (reported by 2 of 3 studies). All studies clearly showed that both membranes were effective in increase bone volume. There was no clear tendency of any of the two membranes in cause more complications. Conclusion: resorbable collagen and nonresorbable e-PTFE membranes are similarly effective in vertical guided-bone regeneration; however, horizontal guided-bone regeneration seems to benefit with the use of non-resorbable ones. Both membranes showed to be effective in guided-bone regeneration and similar in regards to complications(AU)

Objetivo: Esta revisão sistemática avaliou a influência do tipo de membrana (colágeno reabsorvível ou politetrafluoretileno expandido não reabsorvível; e-PTFE) na regeneração óssea guia associada à colocação do implante. Métodos: Qualquer tipo de estudo clínico ou revisão de literatura foi pesquisada nas bases de dados MEDLINE / PubMed e Cochrane. Dois revisores independentes examinaram títulos / resumos de artigos e o texto completo de estudos potencialmente elegíveis. Quando os dados estavam disponíveis, a meta-análise pareada foi realizada usando modelo estatístico aleatório. Resultados: Nove estudos preencheram os critérios de inclusão, considerando 685 implantes em 360 pacientes. A regeneração óssea vertical não diferiu com o uso das duas membranas em 8 dos 9 estudos incluídos. Meta-análise não mostrou maior ganho ósseo vertical ou perda óssea vertical após a regeneração com qualquer uma das membranas. Os resultados mostraram uma tendência de maior ganho ósseo na regeneração óssea guiada horizontal com membranas de e-PTFE não reabsorvíveis (relatadas por 2 de 3 estudos). Todos os estudos mostraram claramente que ambas as membranas foram eficazes no aumento do volume ósseo. Não houve uma tendência clara de qualquer uma das duas membranas em causar mais complicações. Conclusão: o colágeno reabsorvível e as membranas não-reabsorvíveis de PTFE-e são igualmente eficazes na regeneração óssea guiada vertical; no entanto, a regeneração óssea guiada horizontal parece se beneficiar com o uso das membranas não reabsorvíveis. Ambas as membranas mostraram-se eficazes na regeneração óssea guiada e similares em relação às complicações(AU)

Comparação estética entre sistemas cerâmicos sobre substrato escurecido / Esthetic comparison between ceramic systems on darkened substrate

Objetivo: O objetivo deste trabalho foi avaliar visualmente a possível influência de um substrato escurecido no resultado estético de coroas com infraestruturas de dissilicato de lítio ou zircônia. Metodologia: O delineamento foi observacional, transversal e descritivo. Para o experimento, foi selecionado um paciente com necessidade de coroas totais no 11 e 21, onde um dos dois elementos deveria ser escurecido. Uma coroa de dissilicato de lítio foi confeccionada sobre o substrato sem alteração de cor. Para o elemento escurecido foram confeccionadas uma coroa de dissilicato de lítio e uma de zircônia, criando-se duas situações clínicas. Sem conhecimento de qual material foi usado, os avaliadores responderam a um questionário que comparava o resultado estético das coroas de dissilicato de lítio ou zircônia com a coroa de dissilicato de lítio sobre o substrato normal, assim como as duas situações clínicas entre si. No total, 20 cirurgiões-dentistas participaram como avaliadores. Os avaliadores julgaram as restaurações como excelentes, aceitáveis ou inaceitáveis e, após, foi realizada uma análise descritiva das avaliações. Resultados: Os resultados demonstraram que houve diferença estética entre as restaurações de dissilicato de lítio e de zircônia, sendo que o dissilicato de lítio não conseguiu bloquear a cor do substrato, mesmo sendo utilizada uma pastilha opaca (MO). Conclusão: Concluiu-se que em casos de substrato escurecido está indicada a utilização de uma infraestrutura com opacidade suficiente, como a zircônia, podendo ocorrer diferenças visualmente perceptíveis e inaceitáveis caso seja utilizado um material translúcido como o dissilicato de lítio(AU)

Purpose: The objective of this work was to evaluate visually the possible influence of a darkened substrate on the aesthetic result of crowns with infiltrations of lithium disilicate or zirconia. Methodology: The design was observational, transversal and descriptive. For the experiment, a patient with total crowns at 11 and 21 was selected, where one of the two elements should be darkened. A crown of lithium disilicate was made on the substrate without color change. For the darkened element, a crown of lithium disilicate and one of zirconia were created, creating two clinical situations. Without knowing which material was used, the evaluators answered a questionnaire that compared the aesthetic result of the lithium disilicate or zirconia crowns with the lithium disilicate crown on the normal substrate, as well as the two clinical situations. A total of 20 dental surgeons participated as evaluators. The evaluators judged the restorations to be excellent, acceptable or unacceptable, and afterwards a descriptive analysis of the evaluations was performed. Results: The results showed that there was aesthetic difference between the restorations of lithium disilicate and zirconia, and the lithium disilicate could not block the color of the substrate, even though an opaque ingot (MO) was used. Conclusion: It was concluded that in cases of darkened substrate, an infrastructure with sufficient opacity, such as zirconia, with visually perceptible and unacceptable differences, if a translucent material such as lithium disilicate is used(AU)

Lithium disilicate glass-ceramic vs translucent zirconia polycrystals bonded to distinct substrates: Fatigue failure load, number of cycles for failure, survival rates, and stress distribution.

The present study evaluated the fatigue behavior of monolithic translucent zirconia polycrystals (TZ) and lithium disilicate glass-ceramic (LD) bonded to different substrates. Disc-shaped specimens of ceramic materials TZ and LD were bonded to three substrates with different elastic modulus (E) (fiber-reinforced composite (FRC) - softest material, E = 14.9 GPa; titanium alloy (Ti) - intermediary properties, E = 115 GPa; and zirconia (Yz) - stiffest material, E = 210 GPa). The surfaces were treated and bonded with resin cement (disc-disc set-up). Fatigue testing followed a step-stress approach (initial maximum load = 200 N for 5000 cycles, incremental step load = 200 N for 10,000 cycles/step). The fatigue failure load and number of cycles until failure were recorded and statistically analyzed. Fractographic and finite element (FEA) analyzes were conducted as well. TZ ceramic depicted higher fatigue failure load, number of cycles until failure, and survival probabilities than LD, irrespective of the substrate. Moreover, TZ and LD presented better fatigue behaviors when bonded to substrates Ti and Yz in comparison to FRC. FEA revealed lower tensile stresses at restorative material when bonded to stiffer substrates. Fractography showed that the fracture origin started at bottom surface of restorative material (except for TZ bonded to Yz, in which crack initiated at load contact point). Translucent zirconia polycrystals present superior mechanical behavior than lithium disilicate glass-ceramic. The substrate type influences the mechanical performance of monolithic dental ceramics (stiffer substrates lead to better fatigue behavior).

The Influence of Post System Design and Material on the Biomechanical Behavior of Teeth with Little Remaining Coronal Structure.

PURPOSE: To evaluate the influence of different post systems on the biomechanical behavior of teeth with a severe loss of remaining coronal structure. MATERIALS AND METHODS: Fifty standardized bovine teeth (n = 10 per group) were restored with: cast post-and-core (CPC), prefabricated metallic post (PFM), parallel glass-fiber post (P-FP), conical glass-fiber post (C-FP), or composite core (no post, CC). The survival rate during thermomechanical challenging (TC), the fracture strength (FS), and failure patterns (FP) were evaluated. Finite element models evaluated the stress distribution after the application of 100 N. RESULTS: All specimens survived TC. Similar FS was observed among post-containing groups. Groups P-FP and CC presented 100% repairable fractures. The von Mises analysis showed the maximum stresses into the root canal in groups restored with metallic posts. Glass-fiber posts and CC presented the maximum stresses at the load contact point. Glass-fiber groups showed lower stresses in the analysis of maximal contact pressure; CPC led to the highest values of contact pressure. The modified von Mises (mvM) stress in dentin did not show differences among groups. Moreover, mvM values did not reach the dentin fracture limit for any group. CONCLUSIONS: The type of intracanal post had a relevant influence on the biomechanical behavior of teeth with little remaining coronal structure.

Biomechanical behavior of teeth without remaining coronal structure restored with different post designs and materials.

The aim of this study was to access the biomechanical behavior of teeth without remaining coronal structure when restored with posts of different materials and configurations. Fifty bovine teeth (n=10 per group) with standard dimensions were restored as follows: cast post and core (CPC), prefabricated metallic post (PFM), parallel glass-fiber post (P-FP), conical glass-fiber post (C-FP) or composite core (no post, CC). The survival rate during thermomechanical challenging (TC), the fracture strength (FS), and failure pattern (FP) were evaluated. Finite element models were realized to evaluate the stress distribution with a 100N load. All post-containing teeth survived TC, while CC had 30% of failures. CPC and C-FP had the higher fracture strength, but a high number of irreparable fractures (60%), such as PFM (70%). Von Mises analysis has shown the maximum stresses into the canal in groups restored with metallic posts, while glass-fiber posts and CC presented the maximum stresses at load contact point in the crown. CPC led to higher modified von Mises (mvM) stress in the cervical third of dentin. However, mvM values did not reach the dentin fracture limit for any group. Analysis of maximal contact pressure has shown better stress distribution along with the dentin interface in post-containing groups, especially for CPC.