Preheated Composite as an Alternative for Bonding Feldspathic and Hybrid Ceramics: A Microshear Bond Strength Study.

PURPOSE: To evaluate the bond strength between alternative or conventional luting agents and indirect restorative materials. MATERIALS AND METHODS: Blocks of a polymer-infiltrated ceramic network (PICN, Vita Enamic) and a feldspathic ceramic (FEL, Vita Mark II) were sliced and divided according to the luting agent: resin cement (PICN-RC, FEL-RC), flowable composite (PICN-FC, FEL-FC), or preheated composite (PICN-PH, FEL-PH). The ceramic surfaces were polished, etched with 5% hydrofluoric acid for 60 s, and then a silane layer was applied. Cylinders of the luting agents were built up on the ceramic surfaces. In half the samples, the microshear bond strength (µSBS) was tested after 24 h (baseline). The other half was tested after 5000 thermocycles (5°C-55°C) (aging). The failure modes were determined using a stereomicroscope, and the ceramic surfaces were analyzed using a scanning electron microscope. Data were statistically analyzed with two-way ANOVA. RESULTS: Thermocycling reduced the bond strength values of all experimental groups. Regarding FEL, the preheated composite obtained the highest results. Resin cement showed results similar to the flowable composite at baseline and after aging. The highest results of PICN were obtained from the preheated composite followed by resin cement and flowable composite. Significant differences among the three luting agents were observed before and after aging. The most frequent failures among the experimental groups were adhesive and cohesive in the ceramic. CONCLUSION: Bond strength results indicate that the preheated composite can be an alternative for adhesive cementation when applied on the tested feldspathic ceramic or PICN.

Effect of Surface-Etching Treatment, Glaze, and the Antagonist on Roughness of a Hybrid Ceramic after Two-Body Wear.

Stains and glaze are effective procedures for achieving an aesthetic smoothness on indirect restorations. Thus, the effect of surface-etching treatments previous to the stain layer and the glaze application on the occlusal and antagonist wear of a hybrid ceramic were evaluated against different antagonists. Disc-shaped samples were prepared from polymer-infiltrated ceramic network (PICN) blocks. The specimens were divided into eight groups, according to the surface-etching treatment and glaze application: P (polished specimens); PG (polishing plus glaze); E (hydrofluoric acid etching plus stain); EG (acid etching plus stain plus glaze); A (aluminum oxide sandblasting plus stain); AG (sandblasting plus stain plus glaze); S (self-etching primer plus stain); SG (self-etching primer plus stain plus glaze). Half of the samples were subjected to a wear simulation with a steatite antagonist, and the other half was tested using a PICN antagonist. The test parameters were: 15 N, 1.7 Hz, 6 mm of horizontal sliding, 5000 cycles. The discs and the antagonists' masses were measured before and after the wear tests. The average roughness and spacing defects were evaluated. The etching treatment affected the surface and antagonist mass loss when tested against steatite. AG showed the highest mass loss. This influence was not detected when using the PICN antagonist. The glaze application after staining ensures a smoother surface and avoids antagonist wear.

Silver-Coated Silica Nanoparticles Modified with MPS: Potential Antimicrobial Biomaterials Applied in Glaze and Soft Reliner.

Soft reliner and glaze are materials used over full or partial dental prosthesis to prevent excessive pressure on the supporting tissues. They are also indicated as supportive treatment for dental stomatitis, especially when modified by the addition of medications. The objective of the work was to evaluate the antimicrobial effect of silver-coated silica nanoparticles in a glaze and a soft reliner. The nanoparticles were synthesized, characterized, and tested by minimum inhibitory concentration (MIC) for C. albicans SC5314. Then, the nanoparticles were incorporated to a glaze and a soft reliner, which were called nanocomposites. Then, the nanocomposites were divided into six groups (n = 12): CG: glaze/reliner; CR: reliner; G1: glaze + 1% nanoparticles/reliner; G2: glaze + 2.5% nanoparticles/reliner; R1: reliner + 1%; R2: reliner + 2.5%. The nanocomposites were characterized by a goniometer and by a scanning electron microscope. The antibiofilm test was performed against C. albicans SC5314. According to the MIC results, the non-functionalized nanoparticles reduced fungal growth at 1000 µg/mL and the functionalized nanoparticles at 2000 µg/mL. The functionalized nanoparticle had a superior dispersion being selected for the antibiofilm test. There was a reduction of 64% in CFU/specimen count for the glaze, not statistically significant (p = 0.244). For the soft reliner, there was an increase in CFU/specimen with the presence of nanoparticles, still not statistically significant (p = 0.264). In conclusion, it is necessary to conduct new studies to increase the release of silver, thus improving nanoparticles' antifungal potential.

Effect of Light Emission Through an Optical Fiber Device on the Bond Strength of a Hollow Experimental Intraradicular Post.

PURPOSE: To evaluate the effect of irradiation with an optical-fiber device on the bond strength of hollow and partially opaque intraradicular posts. MATERIALS AND METHODS: An optical-fiber accessory tip was attached to a light-curing unit to emit light through the central hollow of an experimental fiberglass post. The samples were divided into 4 groups (n = 80) according to the protocol (Variolink N [light cured] or Multilink N [dual-curing luting material]) and the light-curing mode (performed conventionally or with the optical fiber): GF: light-curing luting material; GFF: light-curing luting material and optical fiber; GD: dual-curing luting material; GDF: dual-curing luting material and optical fiber. The samples were tested immediately or after aging. Push-out bond strength, failure mode, degree of conversion (DC, assessed at the peak of 1750 cm-1), and stress distribution by finite element analysis were performed. Quantitative data were analyzed using 3-way ANOVA (luting material x light curing x depth) and 2-way ANOVA (aging x luting material), followed by Tukey's test. RESULTS: Bond strength was significantly affected by the luting material protocol (p < 0.001), depth (p = 0.010), and light curing mode (p = 0.031). The GFF group revealed higher bond strength in the middle and apical portions. The most frequent failure modes were adhesive in the apical portion for the GFF and GDF groups. The DC was higher for GF and GFF groups. CONCLUSION: Using the optical-fiber device led to superior bond strength results when a dual-curing luting material was used.

Effect of silver-coated silica nanoparticles on the thermal conductivity of thermally activated acrylic resin / Efeito das nanopartículas de sílica revestidas por prata na condutividade térmica da resina acrílica ativada termicamente

Objective: Thermally activated acrylic resins (RAATs) are widely used in dentures as a base material due to their good dimensional stability and biocompatibility. However, their low thermal conductivity is a disadvantage, as it affects acceptance when using dental prostheses. Thus, the objective of this work was to measure the conduction heat in RAATs with and without incorporation of silica and silver nanoparticles (NP) and rigid reline (RR). Material and Methods: For this, samples were made and divided into 10 groups (n = 6). The first five groups were 2-mm-thick samples: G1 (RAAT control), G2 (RAAT + RR control), G3 (RAAT and NP + RR), G4 (RAAT + RR and NP), and G5 (RAAT and RR modified by NP). In the other five groups, 8-mm-thick samples were made: G6 (RAAT control), G7 (RAAT + RR control), G8 (RAAT and NP + RR), G9 (RAAT + RR and NP), and G10 (RAAT and RR modified by NP). The heat that cross the surface of the specimens was quantified using a wireless device. The data were submitted to two-factor ANOVA statistical analysis and Tukey ́s test with a 5% significance level. Results: After measuring the temperature variation as a function of time, it can be observed that there was a statistically significant difference for thermal conduction between the control groups and those modified with NP. Conclusion: Thus, it was possible to conclude that the NP improved the heat conduction in RAAT and in the RR because the nanoparticles have a higher thermal conductivity. (AU)

Objetivo: As resinas acrílicas termicamente ativadas (RAATs) são amplamente utilizada em próteses dentárias como material de base, pois possuem uma boa estabilidade dimensional e biocompatibilidade. Porém, como desvantagem, possuem baixa condutividade térmica, o que prejudica a aceitação do uso de próteses dentárias. Assim, o objetivo deste trabalho foi medir a condução de calor em RAAT com e sem incorporação de nanopartículas de sílica e prata (NP) e reembasador rígido (RR). Material e Métodos: Para isso, foram confeccionadas amostras que foram divididas em 10 grupos (n=6). Os primeiros cinco grupos eram amostras de 2 mm de espessura: G1 (RAAT controle), G2 (RAAT + RR controle), G3 (RAAT e NP + RR), G4 (RAAT + RR e NP) e G5 (RAAT e RR modificados por NP). E nos outros cinco grupos foram feitas amostras com espessura de 8 mm: G6 (RAAT controle), G7 (RAAT + RR controle), G8 (RAAT e NP + RR), G9 (RAAT + RR e NP) e G10 (RAAT e RR modificados por NP). O calor percorrido pela superfície dos corpos ­ de prova foi quantificado por meio de um dispositivo sem fio. Os dados foram submetidos à análise estatística ANOVA dois fatores e teste de Tukey com 5% de significância. Resultados: Após medir a variação da temperatura em função do tempo, pode-se observar que houve diferença estatisticamente significante para a condução térmica entre os grupos controle e os modificados com NP. Conclusão: Assim, foi possível concluir que a NP melhorou a condução de calor na RAAT e no RR, pois as nanopartículas apresentam maior condutividade térmica. (AU)

Effect of Different Surface Treatments on the Bond Strength of the Hybrid Ceramic Characterization Layer.

PURPOSE: Using the microshear bond strength (µSBS) test, this study investigated the bond strength between a hybrid ceramic and the extrinsic characterization layer after different ceramic surface treatments. MATERIALS AND METHODS: Hybrid ceramic blocks (Vita Enamic, Vita Zahnfabrik) were sectioned and randomly divided into 4 groups (N = 120) according to the surface treatment and aging (n = 15): P: polishing; E: acid etching with HF; A: aluminum oxide blasting; S: self-etching ceramic primer. The specimens were silanized, then cylinders of light-curing characterization material (Vita Enamic Stain, 1.6 mm diameter x 2 mm height) were fabricated, followed by glazing. The specimens were subsequently immersed in distilled water for 24 h and subjected to the µSBS test using a universal testing machine (load cell 0.5 mm/min, 50 kgf) or tested after thermocycling for 10,000 cycles in water (5°C-55°C). After treatment, the specimen surfaces were analyzed using SEM, with failure types defined as adhesive, predominantly adhesive, or cohesive. The data were analyzed by two-way ANOVA followed by Tukey's test (p < 0.05). RESULTS: The most frequent failure type was predominantly adhesive between ceramic and the characterization layer. There were statistically significant differences between the surface treatments (p < 0.05). Thermocycling did not lead to statistically signifcant different results (p > 0.05). For groups P and A, a sharp decrease in SBS was observed. CONCLUSION: The absence of surface treatment drastically reduced the microshear bond strength between the ceramic and the characterization layer. Conditioning with 5% hydrofluoric acid for 60 s is the most suitable treatment for adhesion of the characterization layer to hybrid ceramic.

Modified impression technique for extreme mouth-opening limitation caused by systemic scleroderma.

Systemic scleroderma is a relatively rare, autoimmune, chronic, and debilitating disease, and its etiology is unknown. The disease is characterized by vasomotor disturbances causing skin and mucosa hardening, hand stiffness, excess production of collagen fibers, and impairment of the internal organs associated with the immune system. Extreme mouth-opening limitation is one of the symptoms in the oral cavity, and compromises dental intervention. One of the fundamental steps when performing a dental procedure is dental arch impression. In the presented clinical case, limited mouth opening hindered the impression accuracy. The objective was to present an alternative impression technique for a patient affected by scleroderma, with limited mouth opening and the need for oral rehabilitation with a removable partial prosthesis in the maxillary arch. An individualized tray was developed with design characteristics that allowed access to the oral cavity and removal, after which it was possible to perform the oral impression, reproducing the areas of interest without causing injury to the oral tissues. The orientation plan was elaborated after obtaining the cast. The teeth were assembled, tested in the mouth, and sent to the laboratory for acrylization. The prosthesis was placed once ready. The alternative impression technique enabled oral rehabilitation of the patient despite the mouth-opening limitation, and provided an accurate impression and a good prosthetic result.

Full digital workflow in fixed adhesive dental prosthesis: Description of a clinical technique / Fluxo de trabalho digital completo em prótese fixa adesiva: descrição de uma técnica clínica

Digital dentistry has gained space in several dental specialties. It is possible to achieve excellent results with the digital workflow, which combines the efficiency of the restorative material with a greater marginal adaptation. This study aimed to report a clinical case through the digital workflow, with a faster and clinically acceptable prosthetic resolution. In this clinical case report, digital workflow allowed a faster and clinically acceptable prosthetic resolution. A 45-year-old female patient reported cementation failure of the prosthetic crown on tooth 14. As it was a vital tooth, the tooth received a total crown preparation. In the same clinical session, the patient's mouth was scanned then a capture software obtained a virtual model. After, the design software planned a digital "diagnostic wax-up", so a leucitic ceramic was chosen for the rehabilitation. The ceramic block was milled and receive stain and glaze, dispensing the prosthesis laboratory. Then, the adhesive cementation was performed with a dual-polymerized resin cement. The final crown had ideal adaptation, with no need for interproximal and occlusal adjustments, with an excellent marginal fit. Within the limitations of this study, this case report showed that the digital workflow allowed a favorable result in a shorter working time, which brought back function and aesthetics, without the need for interproximal and occlusal adjustments. (AU)

A odontologia digital vem ganhando espaço em diversas especialidades odontológicas. Com o fluxo de trabalho digital, é possível alcançar excelentes resultados na reabilitação protética, combinando a eficiência do material restaurador com a adaptação marginal proporcionada pela odontologia digital. O objetivo desse estudo foi relatar um caso clínico através do fluxo de trabalho digital, com uma resolução protética mais rápida e clinicamente aceitável. Paciente do sexo feminino, 45 anos, relatou falha de cimentação da coroa protética do dente 26. Por ser um dente vital, o dente recebeu um preparo de coroa total e os dentes foram escaneados e um software de captura obteve um modelo virtual. Posteriormente, o software de projeto planejou um "enceramento diagnóstico" digital, sendo escolhida uma cerâmica leucítica para a reabilitação. O bloco cerâmico foi fresado e recebeu acabamento, maquiagem e glaze pelo próprio dentista, dispensando um técnico laboratorial de prótese dentária. Em seguida, foi realizada cimentação adesiva definitiva. Este relato de caso mostra que, dentro das limitações desse estudo, o fluxo digital permite um resultado favorável em um menor tempo de trabalho, devolvendo a função e estética, sem necessidade de ajustes interproximais e oclusais (AU)

Avaliação do comportamento antimicrobiano de um glaze e reembasador modificados por nanopartículas de sílica com prata / Avaliação do comportamento antimicrobiano de um glaze e reembasador modificados por nanopartículas de sílica com prata

O objetivo do trabalho foi avaliar a ação antimicrobiana de um glaze e um reembasador macio com nanopartículas de sílica revestidas por prata. Para isso, foi realizada a síntese e caracterização de nanopartículas de sílica recobertas por prata, que foram avaliadas através do teste de concentração inibitória mínima (CIM) para C. albicans. Após isso, foram confeccionadas amostras e divididas em 6 grupos (n=12): CG: glaze e reembasador macio; CR: reembasador macio; G1: glaze com nanopartículas a 1% e reembasador macio; G2: glaze com nanopartículas a 2,5% e reembasador macio; R1: reembasador macio com nanopartículas a 1%; R2: reembasador macio com nanopartículas a 2,5%. Foram realizados testes de ângulo de contato e efeito anti-biofilme nas amostras. De acordo com o resultado da CIM, houve redução das contagens de fungos após adição de ambas as nanopartículas, não funcionalizada (a 1000 µg/mL) e funcionalizada (a 2000 µg/mL). Para o ângulo de contato, houve uma redução significativa da molhabilidade nos grupos G2 (p=0,001) e R2 (p=0,000). Para o ensaio de biofilme, houve uma redução de 64% na contagem de UFC/espécime para o grupo G1, porém, esta diferença não foi estatisticamente significante (p=0,244). Já para o reembasador, houve um aumento não significativo (p=0,264) de UFC/espécime com a agregação das nanopartículas. Pode-se concluir que houve redução do crescimento fúngico para o teste de CIM nos poços que receberam as nanopartículas. Houve alteração significativa da energia de superfície e molhabilidade nos grupos G2 e R2. Houve uma redução de 64% de UFC/espécime para o grupo G1 quando comparada ao CG, não sendo estatisticamente significativa. Assim, o desenvolvimento de um glaze, nas condições observadas, pode ter potencial antifúngico promissor.

The study aimed to evaluate the antimicrobial action of glaze and soft reline with silver-coated silica nanoparticles. So, silver-coated silica nanoparticles were synthesized and characterized. The test of minimum inhibitory concentration (MIC) for C. albicans evaluated the antimicrobial potential of the nanoparticle. After that, samples were made and divided into six groups (n = 12): CG: glaze and soft reline; CR: soft reline; G1: glaze with 1% nanoparticles and soft reline; G2: glaze with 2.5% nanoparticles and soft reline; R1: soft reline with 1% nanoparticles; R2: soft reline with 2.5% nanoparticles. The contact angle test evaluated the wettability of the samples' surface. The anti-biofilm test evaluated the fungal growth. According to the MIC result, there was a reduction in fungal counts after the addition of both nanoparticles, non-functionalized (at 1000 µg / mL) and functionalized (at 2000 µg / mL). In the contact angle test, the wettability significantly decreased for the group G2 (p = 0.001) and group R2 (p = 0.000). In the anti-biofilm test, there was a reduction of 64% of CFU/specimen count in group G1. As for the reline, there was a non-significant increase (p = 0.264) of CFU/specimen with the aggregation of the nanoparticles. Overall, there was a reduction in fungal growth for the MIC test in the microplates that received the nanoparticles. There was a reduction of 64% of CFU/specimen count in group G1 compared to the CG, which not statistically significant. Thus, the development of a glaze, under the conditions observed, may have promising antifungal potential.

Efficacy of S-PRG filler containing varnishes on enamel demineralization prevention.

This study evaluated the efficacy of S-PRG vanishes on preventing enamel demineralization. Bovine enamel specimens were obtained, polished and the baseline Knoop microhardness was evaluated. Specimens were stratified into six groups (n = 15), according to the varnish applied: S10-experimental varnish containing 10% of S-PRG fillers, S20-20% of S-PRG fillers, S30-30% of S-PRG fillers; S40-40% of S-PRG fillers; PC (positive control)-5% of NaF; NC (negative control)-no treatment was performed. Half of enamel surfaces were protected to work as a control and varnishes were applied over the unprotected area. A demineralizing pH-cycling was performed, and surface and cross-sectional microhardness were measured. The percentage of microhardness of the treated area was calculated comparing with the untreated area. Statistical analysis was performed by one-way ANOVA and Tukey's test (p = 5%). All experimental S-PRG varnishes protected against demineralization in relation to no treatment, but S40 was the most effective on the surface. For all depths, S30 and S40 were superior in enamel demineralization prevention than other S-PRG filler concentrations and 5% NaF. It was concluded that S-RPG filler containing varnishes were effective to prevent enamel demineralization. The higher concentrated products were more effective than 5% sodium fluoride on surface demineralization prevention.

Influence of surface treatments in flexural strength and superficial topography of a lithium disilicate ceramic / Influência dos tratamentos de superfície na resistência à flexão e na topografia superficial de uma cerâmica de dissilicato de lítio

Objective: The aim of the study was to evaluate the influence of different surface post-etching treatments in flexural strength, contact angle and surface roughness of a lithium disilicate ceramic. Material and Methods: 60 bars (16 x 2 x 4 mm) were divided in six groups (n=10): C, no treatment; HF, hydrofluoric acid for 20 s (HF) + washing (60 s), drying (30s); HFL, HF + washing (60 s), drying (30 s) and luting; HFNL, HF + washing (60 s) + neutralization with sodium bicarbonate (SB) for 40 s + washing (5s), drying (30 s) and luting; HFUL, HF + washing (60 s) + ultrasonic bath (UB) for 4 min, drying (30 s) and luting; HFNUL, HF + washing (60 s) + SB (40 s) + UB (4 min) and luting. The bars were submitted to three-points flexural strength test. 25 ceramic blocks (12 x 7 x 7 mm) were divided into five groups (n=5) to evaluate roughness and contact angle C - no treatment; HF - HF ; HFU - HF and UB for 5 min ; HFN - HF and SB; HFNU - HF, UB and SB. A scanning electron microscope (SEM) showed the surface of the samples. ANOVA one-way statistical analysis was done for comparison of results. Results: There was no statistical difference for flexural strength (p-value = 0.15) and for surface roughness (p-valor = 0.15). However, it was obtained statistically significant difference for contact angle (p-valor = 0.00). SEM images showed precipitates after the acid etching, which were removed by post-etching treatments. Conclusion: It can be concluded that the different post-etching surface treatments did not increase the flexural strength, surface roughness, but it influenced the ceramic wetting and SEM images (AU)

Objetivo: O objetivo do estudo foi avaliar a influência de diferentes tratamentos pós-condicionamento na resistência à flexão, ângulo de contato e rugosidade superficial de uma cerâmica de dissilicato de lítio. Material e Métodos: 60 barras (16 x 2 x 4 mm) foram divididas em seis grupos (n = 10): C, sem tratamento; HF, ácido fluorídrico durante 20 s (HF) + lavagem (60 s), secagem (30 s); HFL, lavagem com HF + (60 s), secagem (30 s) e cimentação; HFNL, HF + lavagem (60 s) + neutralização com bicarbonato de sódio (SB) por 40 s + lavagem (5s), secagem (30 s) e cimentação; HFUL, HF + lavagem (60 s) + banho ultrassônico (UB) por 4 min, secagem (30 s) e cimentação; HFNUL, HF + lavagem (60 s) + SB (40 s) + UB (4 min) e cimentação. As barras foram submetidas ao teste de resistência à flexão de três pontos. 25 blocos cerâmicos (12 x 7 x 7 mm) foram divididos em cinco grupos (n = 5) para avaliação da rugosidade superficial e ângulo de contato C - sem tratamento; HF - HF; HFU - HF e UB por 5 min; HFN - HF e SB; HFNU - HF, UB e SB. Um microscópio eletrônico de varredura (MEV) foi utilizado para análise da superfície das amostras. A análise estatística unidirecional ANOVA-um fator foi realizada para comparação dos resultados. Resultados: Não houve diferença estatística para a resistência à flexão (p-valor = 0,15) e para a rugosidade superficial (p-valor = 0,15). No entanto, obteve-se diferença estatisticamente significante para o ângulo de contato (p-valor = 0,00). Imagens de microscopia eletrônica de varredura mostraram a formação de precipitados após o ataque ácido, que foram removidos pelos tratamentos pós-condicionamento. Conclusão: Pode-se concluir que os diferentes tratamentos de superfície pós-condicionamento não aumentaram a resistência à flexão, rugosidade da superfície, mas influenciaram na molhabilidade da cerâmica e nas imagens em MEV.(AU)