Maintenance protocols for implant-supported dental prostheses: A scoping review.

STATEMENT OF THE PROBLEM: Biological complications of implant-supported prostheses remain a concern. Therefore, standardizing hygiene protocols to promote their maintenance is important. PURPOSE: The purpose of this scoping review was to identify available hygiene guidance for home care procedures, as well as periodicity and protocols for the professional maintenance of implant-supported prostheses. MATERIAL AND METHODS: This study was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the study protocol was made available at: https://osf.io/5jdeh/. The search was last performed in the PubMed database on March 15, 2022 and was undertaken by 2 independent researchers. Clinical studies and reviews that evaluated home care and maintenance protocols for dental implant-supported prostheses (fixed or removable), without language restriction or year of publication, were included. A descriptive analysis was performed considering study characteristics (study design, restorative assembly, maintenance strategies, eligibility criteria, number of included studies, quality/level of evidence, and main findings). RESULTS: The initial search yielded 3138 studies, of which 18 were included for descriptive analysis (6 critical reviews, 4 clinical trials, 3 systematic reviews, 2 guideline reports, 2 retrospective studies, and 1 transversal study). The main instrument recommended for home care was the use of a conventional toothbrush associated with triclosan-containing toothpaste in addition to interproximal aids (brushes or floss) for all types of restorations. The use of irrigation instruments was also frequently considered. For professional maintenance, almost all studies reported a positive effect of regular recalls every 3 months during the first year, followed by less regular recalls according to the motivation of the patient and home care efficacy. At each recall, the professional should evaluate the patient history, oral tissues, implant, abutments, and restorations, as well as perform professional cleaning of the prostheses with appropriate instruments so that the implants and abutments may be preserved. CONCLUSIONS: Establishing an adequate hygiene protocol is indispensable for implant-supported restorations. To do so, the professional must guide and support the patient's home care by taking into account the patient's motivation and efficacy during the hygiene procedures. Also, for professional maintenance, the periodicity of recalls should be constant and include an evaluation of the condition of the restoration and adjacent tissues, followed by professional cleaning of prostheses, implants, and abutments, in addition to new instructions to improve patient home care.

Spectrophotometric evaluation of restorative composite shades and their match with a classical shade guide.

OBJECTIVES: The aim of this study was to verify the match between 5 shades of composites from different manufacturers with a shade guide and among the systems using a portable spectrophotometer. MATERIALS AND METHODS: Shade measurements were performed on specimens of Z350 XT (3M ESPE), Charisma Diamond (Heraeus Kulzer GmbH), Esthet X-HD (Dentsply Caulk), and Empress Direct (Ivoclar-Vivadent) for shades A1, A2, A3, B1, and C3 using a Vita Easyshade spectrophotometer (Vita Zahnfabrik) against a white background. Corresponding shades of Vitapan Classical (Vita Zahnfabrik) guide were measured likewise and shade variation (ΔE) was calculated based on International Commission on Illumination L*a*b* parameters. The ΔE of the composites in each shade was compared by one-way analysis of variance and Tukey's post hoc test (α = 0.05). RESULTS: All composites presented ΔE > 3.7 compared with the shade guide. Variation in shades A3, B1, and C3 was significantly different for all composites. ΔE of Z350 XT was significantly lower for A1 than for the other shades, whereas ΔE of Z350 XT and Charisma Diamond were significantly lower for A2 than for the other shades. CONCLUSIONS: No composite shade matched with the shade guide. Equivalent shades of the restorative composite from different manufacturers may show clinically noticeable ΔE.

Como as características dos LEDs de segunda e terceira geração podem influenciar a dureza de compósitos restauradores: uma revisão da literatura / How the second and third LED generation features can influence the hardness of restorative composites: a review of the literature.

Objetivo: Várias fontes de luz têm sido utilizadas desde que os materiais fotoativados foram introduzidos na odontologia. Diodos emissores de luz (LEDs) se popularizaram como a principal opção para a polimerização dos materiais restauradores. O objetivo nessa revisão da literatura foi avaliar a influência das fontes de luz emitidas por diodo (LEDs) de segunda e terceira geração sobre a dureza de compósitos restauradores. Revisão de literatura: Nas bases de dados PubMed e Google Scholar foram pré-selecionados 239 artigos na língua inglesa entre os anos de 2010 e 2020, utilizando os termos: lightcuring, LED light sources, and dental LEDs. Dos 239 artigos inicialmente selecionados, 37 artigos foram avaliados devido aos critérios de inclusão/exclusão no estudo. Considerações finais: Vários estudos apontaram diferenças importantes na dureza dos compósitos restauradores testados, tanto na superfície de topo quanto na base. No entanto, essas diferenças estavam mais associadas a características como: estado de conservação do LED, irradiância, tempo de ativação, espectro de emissão dos aparelhos e sua compatibilidade ao fotoiniciador presente no compósito. Assim, podemos considerar que o monitoramento das condições do aparelho, e a escolha correta da fonte de luz de acordo com o compósito a ser utilizado são essenciais para maximizar a dureza dos compósitos restauradores, pois embora os aparelhos de terceira geração sejam preferencialmente indicados para compósitos com fotoiniciadores alternativos, os aparelhos que emitem luz azul apresentam vantagens quando o compósito é ativado apenas pela Canforoquinona.(AU)

Objective: Several light sources have been used since the light-curing materials were introduced in dentistry. Light-emitting diodes (LEDs) have become popular as the main option for the polymerization of restorative materials. This literature review aimed to evaluate the influence of second and third generation Light-emitting Diode (LEDs) sources on the hardness of restorative composites. Literature Review: In the PubMed and Google Scholar databases, 239 scientific papers in English were pre-selected between 2010 and 2020 using light-curing, LED light sources, and dental LEDs. After reading, 37 articles were selected to compose the review. Several studies have pointed out significant differences in the hardness of the tested restorative composites, both on the top and base surfaces. However, these differences were more associated with characteristics such as: LED conservation conditions, irradiance, curing time, the emission spectrum of the devices and their compatibility with the photoinitiator used in the composite. Final Considerations: Thus, it can be considered that monitoring the condition of the device and the correct choice of light sources according to the composite to be used is essential to maximize the hardness of the restorative composites, because although third-generation devices are preferably indicated for composites with alternative photoinitiators, devices that emit blue light have advantages when the composite is activated only by Camphorquinone.(AU)

Conceitos atuais sobre a performance clínica e principais falhas do tratamento restaurador com laminados cerâmicos: uma revisão da literatura / Current status on clinical performance and main failures of laminate veneers: a review of the literature

O objetivo do presente estudo foi revisar a literatura dos últimos cinco anos e identificar os índices de sobrevivência, principais causas de falha relatadas e verificar a confiabilidade dos laminados cerâmicos como tratamento estético e funcional em longo prazo. Métodos: foi realizada uma busca ativa na Biblioteca Nacional de Medicina dos Estados Unidos (pubmed.ncbi.nlm.nih.gov), através da base de dados Medline, dos últimos cinco anos (2015-2020) na língua inglesa, utilizando os descritores: Laminate Veneers, Porcelain Laminate Veneers e Ceramic Laminate Veneers, que resultou em 35 artigos. Após a leitura dos resumos, foram excluídos 9 estudos que utilizaram laminados cerâmicos não produzidos em cerâmicas feldspáticas, ou vidro ceramizados reforçados por cristais de leucita, ou dissilicato de lítio. Foram selecionados 26 artigos categorizados como: relatos de caso, estudos clínicos, estudos in vitro e revisões de literatura. Resultados: os estudos apontaram índices de sobrevivência de 100%, após 2 anos de cimentação, até valores superiores a 80%, após 14 anos. As três principais causas de falhas apontadas foram: desadaptação de marginal (37%), pigmentação das margens (30%) e fratura ou lascamento das restaurações (3%). Considerações finais: dentro das limitações do estudo, foi possível concluir que as principais causas de falha estão associadas às margens da restauração, no entanto, os laminados cerâmicos podem atingir índices elevados de sobrevivência mesmo 14 anos após a cimentação, mostrando um alto nível de confiabilidade. (AU)

The objective of the present study was to identify the survival rate and cause of failure of ceramic laminate veneers. Methods: An active search of the last five years (2015 ­ 2020) was carried out in the United States National Library of Medicine (pubmed.ncbi.nih.gov) the MEDLINE database, in English, using the descriptors: Laminate Veneers, Porcelain Laminate Veneers and Ceramic Laminate Veneers, which resulted in 35 papers. After reading the abstracts, 9 studies that evaluated ceramic laminates that were not produced using felspathic porcelain, leucite-reinforced glass-ceramicc, or lithium disilicate glass-ceramic were excluded. Twenty-six scientific papers were selected, categorized as: Case reports, clinical studies, in vitro studies and literature reviews. Result: The studies showed survival rates between 100% after two years of cementation up to values above 80% after 14 years. The three causes of failure identified were: marginal misfit (37%), pigmentation of the margins (30%), and fracture or chipping of the restorations (3%). Final Considerations: Within the limitations of this study, it was possible to conclude that the leading causes of failure are associated with the restoration's margins. However, ceramic laminates can achieve high survival rates even 14 years after cementation, showing a high-reliability level.(AU)

Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin.

The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Effects of a bleaching agent on properties of commercial glass-ionomer cements.

OBJECTIVES: This study evaluated the effects of a bleaching agent on the composition, mechanical properties, and surface topography of 6 conventional glass-ionomer cements (GICs) and one resin-modified GIC. MATERIALS AND METHODS: For 3 days, the specimens were subjected to three 20-minute applications of a 37% H2O2-based bleaching agent and evaluated for water uptake (WTK), weight loss (WL), compressive strength (CS), and Knoop hardness number (KHN). Changes in surface topography and chemical element distribution were also analyzed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. For statistical evaluation, the Kruskal-Wallis and Wilcoxon paired tests (α = 0.05) were used to evaluate WTK and WL. CS specimens were subjected to 2-way analysis of variance (ANOVA) and the Tukey post hoc test (α = 0.05), and KH was evaluated by one-way ANOVA, the Holm-Sidak post hoc test (α = 0.05), and the t-test for independent samples (α = 0.05). RESULTS: The bleaching agent increased the WTK of Maxxion R, but did not affect the WL of any GICs. It had various effects on the CS, KHN, surface topography, and the chemical element distribution of the GICs. CONCLUSIONS: The bleaching agent with 37% H2O2 affected the mechanical and surface properties of GICs. The extent of the changes seemed to be dependent on exposure time and cement composition.

Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin

Abstract The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Improving adhesion between luting cement and zirconia-based ceramic with an alternative surface treatment.

This study evaluated the influence of an alternative surface treatment on the microshear bond strength (µsbs) of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO), glass and silane were not applied to the zirconia surface; G1, air blasted with 100µm glass beads + glaze + silane; G2, a gel containing 15% (by weight) glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight) glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight) glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC®, according to the manufacturer's recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The µsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey's test (p < 0.05) were applied to the bond strength values (in MPa). CO (15.6 ± 4.1) showed the lowest µsbs value. There were no statistical differences between the G1 (24.9 ± 7.4), G2 (24.9 ± 2.3), G3 (35.0 ± 10.3) and G4 (35.3 ± 6.0) experimental groups. Those groups submitted to surface treatments with higher concentrations of glass showed a lower frequency of adhesive failures. In conclusion, the glass application improved the interaction between the ceramic and the luting cement.

Improving adhesion between luting cement and zirconia-based ceramic with an alternative surface treatment

This study evaluated the influence of an alternative surface treatment on the microshear bond strength (μsbs) of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO), glass and silane were not applied to the zirconia surface; G1, air blasted with 100μm glass beads + glaze + silane; G2, a gel containing 15% (by weight) glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight) glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight) glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC®, according to the manufacturer’s recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The μsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey’s test (p < 0.05) were applied to the bond strength values (in MPa). CO (15.6 ± 4.1) showed the lowest μsbs value. There were no statistical differences between the G1 (24.9 ± 7.4), G2 (24.9 ± 2.3), G3 (35.0 ± 10.3) and G4 (35.3 ± 6.0) experimental groups. Those groups submitted to surface treatments with higher concentrations of glass showed a lower frequency of adhesive failures. In conclusion, the glass application improved the interaction between the ceramic and the luting cement.

Factors affecting the placement or replacement of direct restorations in a dental school.

CONTEXT: The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future. PURPOSE: The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University - Brazil. MATERIALS AND METHODS: This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05). RESULTS: The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1(st)-time placements, while 39.55% were replacements. For 1(st)-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05). CONCLUSIONS: The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite.

Effect of mouthrinses on the surface roughness of nanofilled composite / Efeito de enxaguantes bucais sobre a rugosidade de superfície de um compósito nanoparticulado

Objective: The aim of this study was to evaluate the effect of mouthrinses on the surface roughness of nanofilled restorative composite. Material and Methods: Twenty Filtek Z350 resin composit discs (4 mm in diameter and 1 mm in height) were made and roughness (μm) was measured by using profilometer with diamond measuring needle tip of 0.5 μm and accuracy of 0.01 μm. The discs were stored in distilled water at 37 °C for 24 h and randomly divided into four groups (n=5): Control – distilled water; Group 1- Plax alcohol free mouthrinse ; Group 2 –Plax Whiteningmouthrinse; Group 3 –Listerine mouthrinseand individually stored in Eppendorf tubes with distilled water at 37 °C. The specimens were maintained in distilled water during 30 days and immersed in mouthrinses every 12 h for 1 min. Elapsed the 30 days, the specimens were cleaned and storedin distilled water, inside anincubatorat 37 °C during 24 h and the surface roughness test was repeated with the same parameters previously described. The data were submitted to Two-way ANOVA. Results: No significant differences among groups were detected for the variables mouthrinse (p = 0.9038) and time (p = 0.2056), R1: Control (0.12 ± 0.04); G1 (0.13 ± 0.05); G2 (0.11 ± 0.03); G3 (0.11 ± 0.02); and R2: Control (0.16 ± 0.04); G1 (0.15 ± 0.02); G2 (0.13 ± 0.01) and G3 (0.15 ± 0.02). Conclusions: In this study the mouthrinses solutions did not promote significant changes in the surface roughness of Filtek Z350 after 30 days.

Objetivo: O objetivo nesse estudo foi avaliar o efeito de enxaguantes bucais sobre a rugosidade superfície de um compósito restaurador nanoparticulado. Material e Métodos: Vinte discos (4 mm de diâmetro e 1 mm de altura) do compósito restaurador Filtek Z350 foram confeccionados e sua rugosidade (μm) foi mensurada utilizando um rugosímetro de contato com ponta de diamante de 0,5 μm e precisão de 0,01 μm. Os discos foram armazenados em água destilada a 37 °C por 24 h, aleatoriamente divididos em quarto grupos (n=5): Controle– água destilada; Grupo 1 –EnxaguantePlaxálcool free; Grupo 2 – Enxaguante PlaxWhitening; Grupo3 – Enxaguante Listerinee armazenados individualmente em Frascos Eppendorfs com água destilada a 37°C. Durante os 30 dias de armazenamento os corpos-de-prova foram imersos nos enxaguantes bucais a cada 12 h por 1 min. Após os 30 dias os corpos-de-prova foram limpos e armazenados em água destilada a 37 °C por 24 h e as medidas de rugosidade refeitas com os mesmos parâmetros descritos anteriormente. Os dados de rugosidade foram submetidos à Análise de Variância de dois fatores. Resultados: Não foram identificadas diferenças significativas entre os grupos para as variáveis enxaguante (p=0,9038) e tempo (p=0,2056), R1: Controle (0,12 ± 0,04); Grupo1 (0,13 ± 0,05); Grupo2 (0,11 ± 0,03); Grupo3 (0,11 ± 0,02); e R2: Controle (0,16 ± 0,04); Grupo1 (0,15 ± 0,02); Grupo2 (0,13 ± 0,01) e Grupo3 (0,15 ± 0,02). Conclusões: No presente estudo, os enxaguantes bucais não promoveram alterações significativas na rugosidade de superfície do compósito Filtek Z350 após 30 dias.

Impact of excess cement removal on vertical misfit and cement line quality in onlays / Impacto da remoção do excesso de cimento sobre desadaptação e qualidade da linha de cimento em onlays

Aim: To evaluate vertical misfit and cement line quality of onlays cemented with resin luting cements using two different methods for removal of excess cement. Materials & Methods: Lithium di-silicate restorations were fabricated and cemented at 24 human molars that received onlay type preparations. The specimens were randomly divided in two groups (n = 12): Group 1 (G1) where cement excess was removed at pre-gel stage and Group 2 (G2) with cement excess was removed after polymerization. Vertical misfits measurements at cement line were performed twice, before and after cementation. Epoxy resin replicas were obtained from the specimens and cement line quality was analyzed with a scanning electron microscope before and after the finishing and polishing procedures. The replicas were also classified according to their condition in unsatisfactory, acceptable or good. Vertical misfits values were submitted to Student test (p < 0.05) and the quality line data were analyzed with Mann-Whitney for independent samples (p < 0.05) and Wilcoxon test for paired specimens (p < 0.05). Results: Vertical misfit and cement line quality presented no difference values to G1 (26.60 ± 8.0) and G2 (24.10 ± 8.0). However, finishing and polishing procedures affect positively the cement line quality in both groups (p = 0.59). Conclusion: The cement excess removal methods had no influence on vertical misfit and cement line quality for restorations. Finishing and polishing procedures improved the cement line quality in both groups.

Objetivo: Avaliar adaptação marginal e a influência do polimento sobre a linha de cimentação de restaurações cerâmicas cimentadas com cimento resinoso utilizando duas formas dois métodos de remoção do excesso do cimento. Métodos: Foram fabricadas restaurações em cerâmica reforçada por dissilicato de Lítio e cimentadas à vinte e quatro molares humanos que receberam preparos protéticos tipo onlay. Os corpos de prova foram divididos aleatoriamente em dois grupos (n = 12): Grupo 1 (G1) em que o excesso de cimento foi removido no estágio pré-gel e Grupo 2 (G2) em que o excesso de cimento foi removido após a polimerização. A mensuração da desadaptação marginal foi realizadas em dois momentos, antes e depois da cimentação. Réplicas em resina epóxi de todos os corpos de prova foram confeccionadas para avaliação da qualidade da linha de cimentação utilizando um microscópio eletrônico de varredura antes de depois dos procedimentos de acabamento e polimento e classificado como insatisfatório, aceitável e boas condições. Os valores de desadaptação foram submetidos ao teste t de Student (p < 0,05) e os dados de qualidade da linha de cimentação foram analisados pelo teste de Mann-Whitney para amostras independentes (p < 0,05) e pelo teste de Wilcoxon para amostras pareadas (p < 0,05). Resultados: A desadaptação marginal e a qualidade da linha de cimentação não apresentaram diferença significativa G1 (26,60 ± 8,0) e G2 (24,10 ± 8,0). Entretanto, os procedimentos de acabamento e polimento influenciaram positivamente a qualidade da linha de cimentação em ambos grupos (p = 0,59). Conclusão: O método de remoção do excesso de cimento não influenciou a adaptação ou a qualidade da linha de cimentação das restaurações cerâmicas. Os procedimentos de acabamento e polimento melhoraram a qualidade da linha de cimento nos dois grupo

Effect of 'Try-in' paste removal method on bond strength to lithium disilicate ceramic.

OBJECTIVES: The aim of this study was to evaluate four methods of Try-in paste removal from a lithium disilicate ceramic surface before cementation and assess the influence on bond strength to a resin luting cement. METHODS: Slices of dentine (1.6mm thick) were sectioned from the crown of human third molars and truncated cone shape cavities were made with diamond burs. IPS e.max Press ceramic blocks were obtained for each cavity, etched with hydrofluoric acid and fixed with temporary paste, except for Group G1, which was cemented according to the manufacturer's instructions. Try-in paste was removed from the experimental groups using different techniques: G2, ultrasonic bath in distilled water (5 min); G3, air/water spray (1 min); G4, etched with phosphoric acid (2 min)+air/water spray (30 s) and G5, etched with phosphoric acid before and after hydrofluoric acid application+air/water spray (30s). The ceramic restorations were cemented with the same procedures as G1. Push-out bond strength testing (MPa) was performed in a universal testing machine with a crosshead speed of 0.5mm/min. RESULTS: One way ANOVA and Tukey's test (P<0.05) were applied: G4(19.21)a, G2(17.09)ab, G1(16.82)ab, G3(16.18)ab and G5(15.9)b. The results showed that all of the experimental groups showed remaining particles of Try-in paste. The bond strength in G4 was statistically higher than in G5. No significant difference was shown in the other groups. There was a predominance of adhesive failures between resin cements and ceramics in G5. CONCLUSION: The techniques used were not totally effective at removing the Try-in paste; however, the presence of remaining material did not influence the bond strength of restorations. The methods of temporary paste removal may affect the bond strength of ceramic restorations.

Avaliação do modo de ativação sobre a resistência à flexão e módulo de elasticidade de compósito restaurador com barras de diferentes formatos / Evaluation of activation modes on flexural strength and elastic modulusof a restorative composite testing bars with different shapes

Introdução e objetivo: O objetivo deste estudo foi avaliar a influência de dois modos de fotoativação sobre resistência à flexão e módulo de elasticidade de um compósito restaurador em dois formatos de barras. Materiais e método: Como controle (CO) foram confeccionadas dez barras seguindo a norma 4049/2000 da ISO (25 x 2 x 2 mm), fotoativadas em modo contínuo por 20s, e vinte barras experimentais com (comprimento x altura x largura) 7 x 1 x 2 mm foram confeccionadas e divididas em dois grupos G1 - fotoativação contínua por 20s e G2 - fotoativação por pulso tardio com ativação inicial de 2s e complementação de 18s após 5min. Após 24h da ativação, o teste foi realizado em uma máquina de ensaios com velocidade constante de 0,5 mm/min e monitorado pelo programa Blue Hill 2, que forneceu os valores de resistência à flexão (MPa) e módulo de elasticidade (GPa). Os valores foram sub-metidos à análise de variância de um fator e ao teste de Tukey (5%). Resultados: CO apresentou os maiores valores de resistência à flexão (158,6 ± 10,6) e módulo de elasticidade (12,20 ± 0,25), quando comparado a G1 (131,65 ± 21,2 e 9,28 ± 3,7) e G2 (131,1 ± 16,9 e 10,1 ± 4,4), que não apresentaram diferença significativa entre si. Conclusão: Foi possível concluir que a barra nas dimensões da ISO apresentou maiores valores de resistência à flexão e módulo de elasticidade que as barras experimentais e que os modos de ativação não influenciaram nas propriedades estudadas entre as barras experimentais.

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.

Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements

Clinicians tend to make reductions in glass ionomer power/liquid (P/L) ratios since some materials are difficult to mix and flow into small cavities, grooves or pits. In general, changing the P/L ratio decreases the physical and mechanical properties of conventional glass ionomer cements (GICs) and resin modified glass ionomer cements (RMGICs), but alterations seem to depend on their composition. OBJECTIVE: To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. MATERIAL AND METHODS: There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50 percent reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs. Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0x8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (α=0.05). RESULTS: There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). CONCLUSIONS: Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction.

Radiodensity evaluation of dental impression materials in comparison to tooth structures.

UNLABELLED: In the most recent decades, several developments have been made on impression materials' composition, but there are very few radiodensity studies in the literature. It is expected that an acceptable degree of radiodensity would enable the detection of small fragments left inside gingival sulcus or root canals. OBJECTIVE: The aim of this study was to determine the radiodensity of different impression materials, and to compare them to human and bovine enamel and dentin. MATERIAL AND METHODS: Twenty-five impression materials, from 5 classes, were studied: addition and condensation silicones, polyether, polysulfides and alginates. Five 1-mm-thick samples of each material and tooth structure were produced. Each sample was evaluated 3 times (N=15), being exposed to x-ray over a phosphor plate of Digora digital system, and radiodensity was obtained by the software Digora for Windows 2.5 Rev 0. An aluminum stepwedge served as a control. Data were subjected to Kruskal-Wallis and Dunn's method (α=0.05). RESULTS: Different materials and respective classes had a different behavior with respect to radiodensity. Polysulfides showed high values of radiodensity, comparable to human enamel (p>0.05), but not to bovine enamel (p<0.05). Human dentin was similar only to a heavy-body addition silicon material, but bovine dentin was similar to several materials. Generally, heavy-body materials showed higher radiodensity than light-body ones (p<0.05). CONCLUSION: Impression materials' radiodensity are influenced by composition, and almost all of them would present a difficult detection against enamel or dentin background in radiographic examinations.

Radiodensity evaluation of dental impression materials in comparison to tooth structures

In the most recent decades, several developments have been made on impression materials' composition, but there are very few radiodensity studies in the literature. It is expected that an acceptable degree of radiodensity would enable the detection of small fragments left inside gingival sulcus or root canals. OBJECTIVE: The aim of this study was to determine the radiodensity of different impression materials, and to compare them to human and bovine enamel and dentin. MATERIAL AND METHODS: Twenty-five impression materials, from 5 classes, were studied: addition and condensation silicones, polyether, polysulfides and alginates. Five 1-mm-thick samples of each material and tooth structure were produced. Each sample was evaluated 3 times (N=15), being exposed to x-ray over a phosphor plate of Digora digital system, and radiodensity was obtained by the software Digora for Windows 2.5 Rev 0. An aluminum stepwedge served as a control. Data were subjected to Kruskal-Wallis and Dunn's method (α=0.05). RESULTS: Different materials and respective classes had a different behavior with respect to radiodensity. Polysulfides showed high values of radiodensity, comparable to human enamel (p>0.05), but not to bovine enamel (p<0.05). Human dentin was similar only to a heavy-body addition silicon material, but bovine dentin was similar to several materials. Generally, heavy-body materials showed higher radiodensity than light-body ones (p<0.05). CONCLUSION: Impression materials' radiodensity are influenced by composition, and almost all of them would present a difficult detection against enamel or dentin background in radiographic examinations.

Bond strength of dental adhesive systems irradiated with ionizing radiation.

PURPOSE: The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. MATERIALS AND METHODS: One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). RESULTS: No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). CONCLUSION: The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.

Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements.

UNLABELLED: Clinicians tend to make reductions in glass ionomer power/liquid (P/L) ratios since some materials are difficult to mix and flow into small cavities, grooves or pits. In general, changing the P/L ratio decreases the physical and mechanical properties of conventional glass ionomer cements (GICs) and resin modified glass ionomer cements (RMGICs), but alterations seem to depend on their composition. OBJECTIVE: To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. MATERIAL AND METHODS: There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs. Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0 x 8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (α=0.05). RESULTS: There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). CONCLUSIONS: Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction.