Determining the widths of the maxillary anterior teeth for esthetics: comparison of the Mondelli and Albers formulas, esthetic proportion, and golden ratio.

The purpose of this study was to compare various formulas for idealized proportions of the maxillary incisors to the actual dimensions of natural teeth. The Mondelli formula 1 (MF1), Mondelli formula 2 (MF2), Albers formula (AF), esthetic proportion (EP) for width and height of anterior teeth, and golden ratio (GR) were calculated for a total of 50 dental students (30 women and 20 men) who participated in the study. The following measurements were obtained directly in the participant's mouth with a digital caliper: the mesiodistal and incisogingival dimensions of the maxillary central incisors, lateral incisors, and canines; the intercanine distance; and the smile width. The participants were photographed, and the smile width was also measured on the photographs. The MF1 and MF2 were each calculated twice, using both direct measurements and photographic measurements. The projected central incisor widths calculated using the MF1, MF2, and AF were compared among themselves and against the actual measurements using analysis of variance and Fisher test for multiple comparisons (α = 0.05). The EP and GR were analyzed using descriptive statistics. There was a statistically significant difference between all of the widths projected by the formulas and the actual widths of the central incisors (P < 0.05). Whether calculated from a direct or a photographic measurement, the incisor widths projected by the MF1 and MF2 were statistically similar to each other (P > 0.05). The EP values were similar to those reported in the literature. Only 2% of the participants had an incisor width ratio (central incisor/lateral incisor) that matched the GR of 1.618, while 86% fell within the range of 1.2 to 1.4. Overall, the proportions calculated with the MF1, MF2, AF, EP, and GR did not exactly match the actual dimensions of natural teeth. The formulas and the proportions available in the literature can assist in esthetic planning, but the individual characteristics of each patient and expertise of the dentist should guide treatment for each case.

The effects of TiO2 nanotubes on bond strength and radiopacity of a self-adhesive resin cement in self-curing mode / Os efeitos de nanotubos de TiO2 na resistência de união e radiopacidade de um cimento resinoso auto-adesivo no modo auto-polimerizável

Objective: The aim of this in vitro study w as t o analyze the influence of the titanium dioxide nanotubes i n a self-cure mode polymerization of a dual resin luting agent through push out bond strength and radiopacity tests. Material and Methods: After mixed with a commercial du al self-adhesive resin cement, three concentrations o f tit anium dioxide nanotubes (0.3, 0.6, and 0.9% by weight) we re analyzed in self-curing mode. T he bond strength to bovine root dentin and fi berglass posts was assessed with the push out bond str ength t est and was evaluated in three thirds (cervical, middle and apical) (n=10), followed by failure mode analysis (SEM), and the ISO standard 9917-2 was followed for radiopacity test (n=10). Data were statistically analyzed by one-way ANOVA test, followed by Tukey's test (α=0.05). Results: Reinforced self-adhesive resin cement with 0.6% titanium dioxide nanotubes showed significant difference compared to the control gr oup for push out test (p=0.00158). The modified groups did not s how significant difference among thirds (p=0.782). Radiopacity sh owed higher value for group w ith 0.9% titanium dioxide nanotubes in comparison w ith control group (p<0.001). Conclusion: The addition of titanium dioxide nanotubes to a self-adhesive resin cement increased the bond strength to dentin and radiopacity values in the self-cure polymerization mode (AU)

Objetivo: O objetivo deste estudo in vitro foi analisar a influência de nanotubos de dióxido de titânio na polimerização química de um agente cimentante resinoso dual através de testes de resistência à união e radiopacidade. Material e Métodos: Após misturado com um cimento resinoso auto-adesivo comercial, três concentrações de nanotubos de dióxido de titânio (0,3, 0,6 e 0,9% em peso) foram analisadas. A resistência da união para a dentina da raiz bovina e os pinos de fibra de vidro foi avaliada pelo teste de push-out e avaliada em três terços (cervical, médio e apical) (n = 10), seguido pelo análise de modo de falha (MEV) e a norma ISO 9917-2 foi seguido para teste de radiopacidade (n = 10). Os dados foram analisados estatisticamente pelo teste ANOVA um fator seguido do teste de Tukey (α = 0,05). Resultados: O cimento resinoso auto-adesivo reforçado com nanotubos de dióxido de titânio a 0,6% mostrou diferença significativa em comparação com o grupo controle para teste de push-out (p=0,00158). Os grupos modificados não mostraram diferença significativa entre os terços (p=0,782). A radiopacidade mostrou maior valor para o grupo com nanotubos de dióxido de titânio 0,9% em comparação com o grupo controle (p<0,001). Conclusão: A adição de nanotubos de dióxido de titânio a um cimento resinoso auto-adesivo aumentou a os valores de resistência de união à dentina e radiopacidade no modo de polimerização química do agente cimentante (AU)

Late discolouration of root-treated teeth and subsequent restorative retreatment: three case reports.

Root-filled teeth that receive ceramic veneers may experience subsequent coronal discolouration, which will likely negatively affect the quality of life of patients and their relationship with the clinician. This manuscript describes three cases of this undesirable aesthetic consequence in anterior teeth of young patients and the subsequent restorative reintervention, with satisfactory results. In all three reports, the root canal filling was performed using cements containing bismuth oxide that likely disassociated into reduced metallic crystals when in contact with LED light. The discolouration observed after veneer cementation was most likely caused by the accumulation of these bismuth metallic crystals. These cases highlight the importance of preventing this undesirable complication, which may also result in the potential subsequent further sacrifice of sound coronal dental structure, and the role of recall in aesthetically demanding clinical cases.

Correlation between mechanical properties and stabilization time of chemical bonds in glass-ionomer cements.

The objective was to evaluate the compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), and Knoop microhardness (KH) of different conventional restorative glass-ionomer cements (GICs) and to correlate these mechanical properties (MP) with the stabilization time (ST) of their chemical bonds. Eighteen GICs were tested: Bioglass [B], Chemfil Rock [CR], Equia Forte [EF], Gold Label 2 [GL2], Gold Label 9 [GL9], Glass Ionomer Cement II [GI], Ionglass [IG], Ion Z[ IZ], Ionomaster [IM], Ionofil Plus [IP], Ionostar Plus [IS], Ketac Molar Easymix [KM], Magic Glass [MG], Maxxion R [Ma], Riva Self Cure [R], Vidrion R [V], Vitro Fil [VF] and Vitro Molar [VM]. The mechanical strength tests were performed in a universal testing machine. KH readings were done with a diamond indenter. STs were examined by Fourier Transform Infrared spectroscopy (FTIR). Data were analyzed with ANOVA and Tukey test (p<0.05). The Spearman rank test was used to evaluate the dependence between the MPs and ST results. The highest MP values were EF, GL2, GL9, GI and KM and the lowest for MG, MA, B, VF and IM. The longest ST was for GL2 and the shortest was for B. ST correlated positively with MP. GICs with longer chemical bonds ST are generally stronger and the ST value obtained from FTIR was useful in predicting the strength of GICs tested.

Ceramic veneers on teeth with non-carious cervical lesions: case report and finite element analysis / Facetas cerâmicas em dentes com lesões cervicais não cariosas: relato de caso e análise de elementos finitos

On ceramic veneers rehabilitation, teeth with non-carious cervical lesions (NCCLs), especially premolars, are often involved. Preparation to remove deep NCCLs may lead to excessive wear and a less conservative approach, which goes against the current principles of minimal wear and maximum preservation. However, no evidence exists indicating which technique could avoid excessive wear during the dental preparation for veneers associated with NCCL. Thus, this study aimed to present an aesthetic treatment with ceramic veneers and follow-up of 24 months of a patient with various levels of NCCL severity; and to evaluate various wear protocols for dental veneers associated with NCCL via Finite Element Analysis (FEA) to guide and justify the clinical decision of the clinical case described. A 37-year-old male patient presented for treatment with wear on the anterior teeth and with NCCLs of various severity degrees on the posterior teeth. The treatment chosen was rehabilitation with ceramic veneers on teeth 15 to 25. The best restorative approach for the NCCL teeth was evaluated via an FEA, simulating various protocols and lesion depths while also calculating the percentage of tooth structure loss. Restoring the premolar's deeper NCCL with a composite resin core, before a ceramic veneer impression, presented better mechanical behavior in FEA and less tooth wear. For the 1.0 mm NCCL, beveling the lesion promoted good stress distribution, less invasive wear and an easier clinical procedure, as it did not involve a previous restorative procedure. It could be concluded that the restorative decision for premolars with NCCLs that will receive veneers should consider the set biomechanical behavior and especially the tooth structure wear necessary. For the case report presented, after two years of follow-up, no changes from the immediate result were observed, indicating that the cause of the lesions was eliminated, and that the treatment was effective, at least in the short-term. For FEA analysis, restoring the deeper NCCL prior to ceramic veneer impression, presented better mechanical behavior and less tooth wear. For the 1.0 mm NCCL, beveling the margin of the lesion generated the same good results

Na reabilitação com facetas cerâmicas, dentes com lesões cervicais não cariosas (LCNC), especialmente pré-molares, estão frequentemente envolvidos. O preparo para remover a LCNC pode levar a um desgaste excessivo e a uma abordagem menos conservadora, o que vai contra os princípios atuais de mínimo desgaste e máxima preservação. Entretanto, não existem evidências indicando qual técnica pode evitar o desgaste excessivo durante o preparo para facetas associado com LCNC. Portanto, esse artigo tem dois objetivos principais: 1) apresentar um tratamento estético com facetas cerâmicas e acompanhamento de 24 meses de um paciente com vários níveis de severidade de LCNC e 2) avaliar vários protocolos de preparo para facetas cerâmicas associadas com LCNC por meio do Método de Elementos Finitos (MEF) para guiar e justificar a decisão clínica do caso clínico descrito. Um paciente de 37 anos, gênero masculino, compareceu para tratamento com desgaste nos dentes anteriores e com LCNC com vários graus de severidade nos dentes posteriores. Optou-se pela reabilitação com facetas cerâmicas nos dentes 15 a 25. A melhor abordagem restauradora para os dentes com LCNC foi avaliada por MEF, simulando vários protocolos e profundidades de lesão, além disso foi calculada a porcentagem de estrutura dental perdida. Restaurar a LCNC profunda de um pré-molar com um núcleo de resina composta, antes da moldagem para faceta cerâmica, apresentou melhor comportamento mecânico em MEF e menos desgaste dental. Para a LCNC de 1 mm, biselar a lesão promoveu boa distribuição de tensões, um desgaste menos invasivo e um procedimento clínico mais fácil, já que não envolveu um procedimento restaurador prévio. Pode-se concluir que a decisão restauradora para pré-molares com LCNC que irão receber facetas deve considerar o comportamento biomecânico do conjunto e, principalmente, o desgaste de estrutura dental necessário. Para o caso apresentado, após 2 anos de acompanhamento, nenhuma mudança foi observada, indicando que a causa das lesões foi eliminada, e que o tratamento foi efetivo, ao menos no curto prazo. Para MEF, restaurar a LCNC antes da moldagem para facetas, apresentou melhor comportamento mecânico e menor desgaste dentário. Para a LCNC de 1,0 mm, fazer o bisel na margem da lesão levou aos mesmos bons resultados.

Yttria-stabilized tetragonal zirconia polycrystal/resin luting agent bond strength: Influence of Titanium dioxide nanotubes addition in both materials.

PURPOSE: To evaluate the shear bond strength (SBS) between Y-TZP and a resin luting agent, after 1 of 2 enhancing strategies with TiO2--nts was applied, either to the resin luting agent or the Y-TZP mass, in different concentrations. METHODS: In the Strategy TiO2-nts on ceramic, the resin luting agent Panavia F2.0™ (Kuraray) and an experimental Y-TZP with added concentrations of TiO2--nts (0%, 1%, 2%, and 5% vol/vol) and a commercial Y-TZP, comprised 5 different groups (n = 10). In the Strategy TiO2-nts on cement, the resin luting agent RelyX U200™ (3 M ESPE) was added with different concentrations of TiO2--nts (0%, 0.3%, 0.6%, 0.9% wt/wt) luted to a commercial Y-TZP, comprising 4 different groups (n = 10). The Y-TZP discs were included in acrylic bases, and a cylinder (3 × 3 mm) of the correspondent luting agent for each respective group was applied over them. After 24 h, specimens were subjected to SBS assessments in a universal testing machine. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy analyses were also performed on Y-TZP surfaces. Data were analyzed via analysis of variance and Tukey tests (α = 0.05). RESULTS: TiO2-nts on ceramic influenced the bond strength significantly, but not linearly; TiO2-nts on cement did not influence bond strength when analyzed separately, nor in comparison with the first. CONCLUSION: Y-TZP enhancements with TiO2-nts led to a higher SBS with Panavia F2.0, a 5% TiO2--nt concentration presented the highest bond strength. Modified Rely X U200 did not improve SBS.

Correlation between mechanical properties and stabilization time of chemical bonds in glass-ionomer cements

Abstract The objective was to evaluate the compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), and Knoop microhardness (KH) of different conventional restorative glass-ionomer cements (GICs) and to correlate these mechanical properties (MP) with the stabilization time (ST) of their chemical bonds. Eighteen GICs were tested: Bioglass [B], Chemfil Rock [CR], Equia Forte [EF], Gold Label 2 [GL2], Gold Label 9 [GL9], Glass Ionomer Cement II [GI], Ionglass [IG], Ion Z[ IZ], Ionomaster [IM], Ionofil Plus [IP], Ionostar Plus [IS], Ketac Molar Easymix [KM], Magic Glass [MG], Maxxion R [Ma], Riva Self Cure [R], Vidrion R [V], Vitro Fil [VF] and Vitro Molar [VM]. The mechanical strength tests were performed in a universal testing machine. KH readings were done with a diamond indenter. STs were examined by Fourier Transform Infrared spectroscopy (FTIR). Data were analyzed with ANOVA and Tukey test (p<0.05). The Spearman rank test was used to evaluate the dependence between the MPs and ST results. The highest MP values were EF, GL2, GL9, GI and KM and the lowest for MG, MA, B, VF and IM. The longest ST was for GL2 and the shortest was for B. ST correlated positively with MP. GICs with longer chemical bonds ST are generally stronger and the ST value obtained from FTIR was useful in predicting the strength of GICs tested.

Influência do Uso da irrigação Durante o Acabamento e Polimento de Resinas Compostas: Rugosidade Superficial, Estabilidade de Cor e Morfologia de Superfície / Influence of Wet Finishing and Polishing on Composite Resins: Surface Roughness, Color Stability and Surface Morphology

Objetivo: Avaliar rugosidade superficial (RS), estabilidade de cor (EC) e morfologia de superfície (MS) de um compósito nanoparticulado após diferentes protocolos de acabamento/ polimento com ou sem irrigação. Material e métodos: Cem espécimes foram confeccionados e divididos em 10 grupos (n=10) conforme protocolo de acabamento/polimento: Tira de poliéster; discos abrasivos (DA); DA+espirais (DAE); DA+multi- -laminada+espirais (DAME); espirais (E); e nenhum polimento. Protocolos com DA, DAE, DAME, e E foram realizados a seco e com irrigação. Após acabamento/polimento, os espécimes foram armazenados em água destilada à 37°C. Durante 14 dias, cinco espécimes de cada grupo foram imersos em café por 5min/dia. A EC foi analisada com Espectrofotômetro (CIEL*a*b*) 0, 7 e 14 dias após armazenamento em água ou imersão em café. A RS foi analisada com Rugosímetro (parâmetro Ra) e MS foi analisada com Microscopia Eletrônica de Varredura (MEV). ANOVA, Tukey e Teste T foram realizados para comparações entre os grupos (α=0,05). Resultados: A irrigação promoveu maior EC nos protocolos DAE e E. Os diferentes protocolos promoveram variação de cor semelhante após 14 dias de armazenamento em água. O protocolo E a seco promoveu os maiores valores RS, sendo inferior ao grupo DAME, que promoveu menor rugosidade e foi semelhante aos demais protocolos. Para DAME e E a irrigação foi significativa para diminuir a rugosidade. Na análise por MEV, E com irrigação apresentaram maior lisura superficial. Conclusão: A irrigação durante acabamento/polimento influencia na EC, RS e MS de compósitos. Os protocolos de acabamento/ polimento DAME e E com irrigação foram mais efetivos.

Aim: to evaluate the surface roughness (SR), color stability (CE) and surface morphology (SM) of a nanofilled composite resin exposed to different finishing/ polishing protocols with or without irrigation. Material and methods: One hundred specimens were prepared and divided into 10 groups (n = 10) according to the finishing/polishing protocol: positive control; abrasive discs (AD); AD + spirals (ADS); AD + multi-laminated + spirals (ADMS); spirals (S); and none. Protocols with AD; ADS; ADMS and S were performed to dry or with irrigation. After finishing/ polishing, the samples were stored in distilled water at 37 ° C. For 14 days, five samples of each group were immersed in coffee for 5min/day. The other samples have been stored in water. The CE of the samples was analyzed with Spectrophotometer (CIEL * a * b *) 0, 7 and 14 days after storage in water or coffee. The SR was analyzed with the Rugosimeter and the SM was analyzed with Scanning Electron Microscopy (SEM). ANOVA, Tukey and T-test were performed for comparisons between the groups (α=0,05). Results: Irrigation offered higher EC in the ADS and S groups. The benefits of color variation are after 14 days. The use of dry spirals promoted the highest SR values, being lower in the ADMS group, which promoted less roughness and was similar to the other protocols. For ADMS and S the irrigation was significant to decrease the roughness. Analysis by MEV, spirals with irrigation greater superficial smoothness. Conclusion: Irrigation during finishing/polishing influences the CS, SR and SM of composites. The finishing/polishing protocols with ADMS and S with irrigation were more effective.

Comparação de Diferentes Técnicas de Moldagem com Silicone de Adição - Estudo in vitro / Comparison of Different Impression Techniques With Addition Silicone - in vitro Study

Objetivo: Comparar diferentes técnicas de moldagem com silicone de adição, quanto à precisão e fidelidade da cópia através de medidas manuais e sobreposição em CAD/CAM. Material e método: Foram realizadas 4 moldagens com silicone de adição de um mesmo modelo nas seguintes técnicas: T1 ­ dois passos com recorte; T2 ­ dois passos com alívio de filme PVC; T3 ­ dois passos sem alívio e T4 - simultânea. A fidelidade das 4 técnicas de moldagem foi avaliada por meio de mensurações de 5 dimensões nos modelos de gesso vazados em cada um dos moldes obtidos. Outra forma de análise foi a sobreposição de imagens no CAD/CAM, com a finalidade de verificar se há semelhanças ou diferenças dimensionais entre o modelo piloto e as amostras. As medidas obtidas foram submetidas ao teste ANOVA com comparações múltiplas pelo teste de Tukey (α=0,05). Resultados: De acordo com as mensurações, a técnica que apresentou maior discordância do modelo piloto foi a T4, não havendo diferença entre as outras técnicas. Na avaliação em CAD/CAM, as técnicas T4 e T3 apresentaram maiores diferenças em relação ao modelo original de acordo com as imagens sobrepostas. Conclusões: Todas as técnicas estudadas apresentaram alterações dimensionais, em especial a técnica simultânea e a sem alívio, tanto nas medidas obtidas quanto na análise em CAD/CAM.

Objetives: To compare different impression techniques with addition silicone, by means of copy accuracy through manual measurements and overlaping in CAD/CAM. Material and methods: Four impressions of a same pilot model were carried out with silicone addition in different techniques: T1 ­ two steps with cut-back; T2 ­ two steps with PVC film relief; T3 ­ two steps without relief; and T4 ­ one step. The accuracy of the 4 different impression techniques was assessed by measuring 5 dimensions on stone casts poured from the impressions of the pilot model. Another analysis was carried out in CAD/CAM using the overlaping of the casts and the pilot model, in order to verify dimensional similarities and differences between them. The values obtained were submitted to ANOVA and Tukey test, for multiple comparisons (α=0.05). Results: According to the measures done, the technique that generated the greatest difference from the pilot model was T4, with no difference among the other techniques. In CAD/CAM analysis, techniques T4 and T3 presented more differences from the original model. Conclusions: All studied techniques presented dimensional changes, mainly the 1 step and the 2 step without relief, in both methods, measures and CAD/CAM analysis.

Pre-sintered Y-TZP sandblasting: effect on surface roughness, phase transformation, and Y-TZP/veneer bond strength.

OBJECTIVES.: Sandblasting is a common method to try to improve the Y-TZP/veneer bond strength of dental prostheses, however, it may put stress on zirconia surfaces and could accelerate the t→m phase transformation. Y-TZP sandblasting before sintering could be an alternative to improve surface roughness and bonding strength of veneering ceramic. The aim of this study was to analyze the effect of Y-TZP pre-sintering sandblasting on surface roughness, phase transformation, and the Y-TZP/veneer shear bond strength. MATERIAL AND METHODS.: The Y-TZP specimen surface underwent sandblasting with aluminum oxide (50 µm) pre-sintering (Z-PRE) and post-sintering (Z-POS). Z-CTR was not subjected to surface treatment. After ceramic veneer application, the specimens were subjected to shear bond testing. Surface roughness was analyzed by confocal microscopy. Y-TZP monoclinic and tetragonal phases were evaluated by micro-Raman spectroscopy. Shear bond strength and surface roughness data were analyzed by One-way ANOVA and Tukey tests (α=0.05). Differences in the wave numbers and the broadening bands of the Raman spectra were compared among groups. RESULTS.: Z-POS (9.73±5.36 MPa) and Z-PRE (7.94±2.52 MPa) showed the highest bond strength, significantly higher than that of Z-CTR (5.54±2.14 MPa). The Ra of Z-PRE (1.59±0.23 µm) was much greater and significantly different from that of Z-CTR (0.29±0.05 µm) and Z-POS (0.77±0.13 µm). All groups showed bands typical of the tetragonal (T) and monoclinic (M) phases. Y-TZP sandblasting before sintering resulted in rougher surfaces but did not increase the shear bond strength compared to post-sintering and increased surface defects. CONCLUSIONS.: Surface treatment with Al3O2, regardless of the moment and application, improves the results of Y-TZP/veneer bonding and is not a specific cause of t→m transformation.

Pre-sintered Y-TZP sandblasting: effect on surface roughness, phase transformation, and Y-TZP/veneer bond strength

Abstract Sandblasting is a common method to try to improve the Y-TZP/veneer bond strength of dental prostheses, however, it may put stress on zirconia surfaces and could accelerate the t→m phase transformation. Y-TZP sandblasting before sintering could be an alternative to improve surface roughness and bonding strength of veneering ceramic. Objectives. The aim of this study was to analyze the effect of Y-TZP pre-sintering sandblasting on surface roughness, phase transformation, and the Y-TZP/veneer shear bond strength. Material and Methods. The Y-TZP specimen surface underwent sandblasting with aluminum oxide (50 μm) pre-sintering (Z-PRE) and post-sintering (Z-POS). Z-CTR was not subjected to surface treatment. After ceramic veneer application, the specimens were subjected to shear bond testing. Surface roughness was analyzed by confocal microscopy. Y-TZP monoclinic and tetragonal phases were evaluated by micro-Raman spectroscopy. Shear bond strength and surface roughness data were analyzed by One-way ANOVA and Tukey tests (α=0.05). Differences in the wave numbers and the broadening bands of the Raman spectra were compared among groups. Results. Z-POS (9.73±5.36 MPa) and Z-PRE (7.94±2.52 MPa) showed the highest bond strength, significantly higher than that of Z-CTR (5.54±2.14 MPa). The Ra of Z-PRE (1.59±0.23 µm) was much greater and significantly different from that of Z-CTR (0.29±0.05 µm) and Z-POS (0.77±0.13 µm). All groups showed bands typical of the tetragonal (T) and monoclinic (M) phases. Y-TZP sandblasting before sintering resulted in rougher surfaces but did not increase the shear bond strength compared to post-sintering and increased surface defects. Conclusions. Surface treatment with Al3O2, regardless of the moment and application, improves the results of Y-TZP/veneer bonding and is not a specific cause of t→m transformation.

Forças de contração de polimerização em resinas compostas constituídas com novas matrizes orgânicas e fotoativadas por diferentes técnicas / Polymerization shrinkage stress of composite resins containing new organic matrices and photocured by different techniques

Objetivo: Verificar a força de contração de polimerização de três diferentes resinas compostas em função de dois métodos de fotopolimerização (convencional e pulso tardio). Foram selecionados para o estudo três materiais, com diferentes matrizes orgânicas: Bis-GMA ­ Filtek Z250 XT (3M-ESPE, Saint Paul, Minnesotta, EUA); Silorano ­ Filtek P90 (3M-ESPE, Saint Paul, Minnesotta, EUA) e TCD-Uretano - Charisma Diamond (Heraeus Kulzer, São Paulo, São Paulo, Brasil). Material e Método: Os corpos de prova foram confeccionados a partir de uma matriz retangular de aço inoxidável (6mm x 1mm x 2mm), posicionados em uma máquina de ensaios universal (Instron, Modelo 5965) para registro da força de contração de polimerização (Newtons). A fotoativação foi executada em cada grupo com fonte de luz do tipo LED (600mW/cm2) sob dois protocolos de fotoativação: contínuo - 40s (600mW/cm2) e pulso tardio - 5s (600mW/cm2) + 1 min sem luz + 35s (600mW/ cm2). Considerou-se como força de contração o valor registrado pela máquina de ensaios 2 minutos após o início da aplicação da luz no espécime. Os valores obtidos foram submetidos à análise de variância (ANOVA), seguido pelo teste de Tukey (p=0,05). Resultados: Não houve diferença estatística significativa entre as duas técnicas de polimerização testadas nas resinas compostas à base de silorano e TCD-Uretano, porém, houve diferença para a resina à base de Bis-GMA. Conclusão: A técnica de pulso influenciou positivamente na redução da força de contração em matriz polimérica à base de Bis-GMA, entretanto, não promoveu benefícios para as resinas à base de silorano e TCD-Uretano. PALAVRAS-CHAVE: Contração; Fotopolimerização

Purpose: To evaluate the polymerization shrinkage stress of three different composite resins cured with two methods photopolymerization (conventional and pulse delay). Three materials were selected for the study, with different organic matrices: Bis- GMA - Filtek Z250 XT (3M-ESPE, Saint Paul, Minenesotta, USA); Silorano - Filtek P90 (3M-ESPE, Saint Paul, Minenesotta, USA) e TCD-Uretane - Charisma Diamond (Heraeus Kulzer, São Paulo, São Paulo, Brazil). Materials and Method: The samples were made from a stainless steel matrix with rectangular internal geometry (6mm x 1mm x 2mm), which was mounted in an universal testing machine (Instron, Model 5965) in order to register the polymerization shrinkage stress (Newtons). The photoactivation was performed in each group with a LED (600mW/cm) light source, under two photoactivation protocols: continuous - 40s (600mW/cm) and pulse delay - 5s (600mW/cm) + 1 min with no light + 35s (600mW/cm). It was considered as shrinkage stress the value registered by the testing machine two minutes after the start of the specimen's cure. The values obtained were subjected to Analysis of Variance (ANOVA), followed by the Tukey test (p=0.05). Results: There was no significant statistical difference between the two polymerization techniques tested in the composite resins based on silorane and TCD-Urethane, but there was difference in the resin based on Bis-GMA. Conclusion: The pulse delay technique positively influenced in reducing the shrinkage stress in the polymeric matrix made of Bis- GMA, but did not provide benefits to resins made of silorane and TCD-Urethane.

Does Post-etching Cleaning Influence Bond Strength of Lithium Disilicate Laminate Veneers?

This paper aims to present a clinical case of laminate veneers in lithium disilicate (LD) reinforced ceramic, complemented with scanning electron microscopy and energy dispersive x-ray spectroscopy analysis of this ceramic's surfaces submitted to some of the different post-etching cleaning protocols proposed by literature. Many dentists are applying all-ceramic restorations, especially veneers, with the most applied material being LD, due to its good mechanical properties, esthetics, and ability to adhere to tooth substrate. The cementation process is critical to clinical success of indirect restorations. Combination of hydrofluoric acid and silane application on the inner surface of ceramic has been the most recommended method to increase bond strength between ceramic and tooth substrate. As a result of surface corrosion, residual subproducts are formed and precipitate on the ceramic surface, affecting the bonding process to the resin cement. Elimination of residue is recommended in the literature and can be done via 3 common techniques: thorough washing with air/water spray for 30 seconds, 37% phosphoric acid for 60 seconds, or ultrasonic bath for 4 to 10 minutes. Little information on LD ceramics post-etching cleaning methods is available in the literature. For this ceramic, the thorough washing with air/water spray for 30 seconds appeared to remove most of the residue without damaging the material. Being also the most practical and easiest of the reviewed procedures, it was, therefore, the protocol of choice for the clinical cases presented in this paper with success after 18 months.

Silver nanoparticles in resin luting cements: Antibacterial and physiochemical properties.

BACKGROUND: Silver has a long history of use in medicine as an antimicrobial and anti-inflammatory agent. Silver nanoparticles (NAg) offer the possibility to control the formation oral biofilms through the use of nanoparticles with biocidal, anti-adhesive, and delivery abilities. This study aims to evaluate the antibacterial effect of resin luting cements with and without NAg, and their influence on color, sorption and solubility. MATERIAL AND METHODS: NAg were incorporated to two dual-cured resin cements (RelyX ARC (RA) color A1 and RelyX U200 (RU) color A2) in two concentrations (0.05% and 0.07%, in weight), obtaining six experimental groups. Disc specimens (1x6mm) were obtained to verify the antibacterial effect against Streptococcus mutans in BHI broth after immersion for 1min, 5min, 1h, 6h, and 24h (n=3), through optical density readings. Specimens were evaluated for color changes after addition of NAg with a spectrophotometer (n=10). Sorption and solubility tests were also performed, considering storage in water or 75% ethanol for 28 days (n=5), according to ISO 4049:2010. Data were subjected to statistical analysis with ANOVA and Tukey (p=0.05). RESULTS: The optical density of the culture broths indicated bacterial growth, with and without NAg. NAg produced significant color change on the resin cements, especially in RA. Solubility values were very low for all groups, while sorption values raised with NAg. The cements with NAg did not show antibacterial activity against S. mutans. They also showed perceptible color change and higher sorption than the materials without NAg. CONCLUSIONS: The resin luting cements with NAg addition did not show antibacterial activity against SS. mutans. They also showed perceptible color change and higher sorption than the materials without NAg. Key words:Silver, resin cements, products with antimicrobial action, solubility, color perception tests.

Influência do adesivo no resultado cromático imediato e após envelhecimento acelerado das "lentes de contato'': in vitro / Influence of the adhesive on the imediate chromatic result and after accelerated aging of non-prep veneers: an in vitro study

O objetivo deste estudo foi avaliar a influência do sistema adesivo no resultado cromático de "lentes de contato" de alta translucidez imediatamente após a cimentação e após envelhecimento artificial acelerado (EAA). Quarenta dentes bovinos e 40 discos de cerâmica (IPS eMax) cor HT-BL1 com 0,5 mm de espessura foram distribuídos em quatro grupos: GI- Scotchbond Multi-Purpose; GII - Single Bond 2; GIII - Single Bond Universal (usado no dente como adesivo apenas); e GIV - Single Bond Universal (usado no dente e na peça como silano). Os dentes e a cerâmica foram tratados previamente à cimentação, respeitando-se os grupos experimentais, e o cimento Variolink Veneer valor 0 foi utilizado para cimentação. Todos os espécimes foram submetidos a 400 h de EAA. Foi realizada a mensuração da cor com espectrofotômetro Easyshade em três momentos: 1) substrato dentário; 2) disco cimentado; e 3) após EAA. Os valores de L*, a*, b*, ΔE1* e ΔE2* foram submetidos a análise estatística em SPSS 17.0 para Windows com uma significância de 5% (p<0,05). Os adesivos testados neste estudo não influenciaram nas cores das "lentes de contato" cimentadas em dentes bovinos com cimento translúcido, imediatamente ou após EAA, porém todos os grupos apresentaram mudança de cor perceptível após o envelhecimento(AU)

The purpose of this study was to evaluate the influence of the adhesive system on the shade of highly translucent ceramic "contact lens" veneers immediately after cementation and after acce-lerated artificial aging (AAA). Forty bovine teeth and 40 ceramic discs (IPS eMax, HT,BL1, 0.5mm thickness) were divided in four experimental groups: GI- Scotchbond Multi-purpose; GII - Single Bond 2; GIII - Single Bond Universal (applied on teeth as adhesive only) and GIV - Single Bond Universal (applied in teeth as adhesive and also on ceramic as a coupling agent). Teeth and ceramic disks were treated prior to cementation with the respective manufacturers' instructions for each experimental group, and the cement used was Variolink Veneer (Value 0). All the specimens were then subjected to 400 hours of AAA. Shade was measured with a spectrophotometer (Easyshade, Vita, Yorba Linda, CA, USA) in three moments: 1) before cementa-tion on the dental substrate, 2) on the cemented disc immediatly after cementation, and 3) after AAA. L*, a*, b*, ΔE1*, and ΔE2* values were submitted to statistical analysis (SPSS 17.0 for Windows) with a significance level of 5% (p<0.05). The tested adhesives in this study did not influence the shade of the non-prep ceramic veneers cemented in bovine teeth with a translucent resin cement, immediately or after AAA, although all groups presented perceptible color change after aging(AU)

Cytotoxicity of glass ionomer cements containing silver nanoparticles.

BACKGROUND: Some studies have investigated the possibility of incorporating silver nanoparticles (NAg) into dental materials to improve their antibacterial properties. However, the potential toxic effect of this material on pulp cells should be investigated in order to avoid additional damage to the pulp tissue. This study evaluated the cytotoxicity of conventional and resin-modified glass ionomer cements (GIC) with and without addition of NAg. MATERIAL AND METHODS: NAg were added to the materials at two different concentrations by weight: 0.1% and 0.2%. Specimens with standardized dimensions were prepared, immersed in 400 µL of culture medium and incubated at 37°C and 5% CO2 for 48 h to prepare GIC liquid extracts, which were then incubated in contact with cells for 48 h. Culture medium and 0.78% NAg solution were used as negative and positive controls, respectively. Cell viability was determined by MTT and Trypan Blue assays. ANOVA and the Tukey test (α=0.05) were used for statistical analyses. RESULTS: Both tests revealed a significant decrease in cell viability in all groups of resin modified cements (p<0.001). There were no statistically significant differences between groups with and without NAg (p>0.05). The differences in cell viability between any group of conventional GIC and the negative control were not statistically significant (p>0.05). CONCLUSIONS: NAg did not affect the cytotoxicity of the GIC under evaluation. KEY WORDS: Glass ionomer cements, totoxicity, cell culture techniques, nanotechnology, metal nanoparticles.

Shade evaluation of ceramic laminates according to different try-in materials.

The porcelain laminate replaces the visible portion of enamel with a ceramic, which is attached to the dental surface. To enhance cosmetic results, a preliminary color matching procedure is performed prior to cementing the veneers. This procedure can be performed using water, water-soluble gel, or try-in paste. The different shades of cement and try-in pastes are intended to obtain better color and esthetics of the final restoration. This study sought to evaluate the shade of ceramic veneers produced by different try-in materials. Forty bovine teeth and 40 ceramic discs (0.6 mm thick) were prepared. The samples were divided into 4 groups (n = 10). For Group 1 samples, no material was used between the tooth and the ceramic, Group 2 interposed samples with water, Group 3 used a water-soluble gel, and Group 4 used try-in paste (value 0). The color was measured with a spectrophotometer, obtaining L*, a*, and b* values to calculate the color difference (ΔE*). The data were subjected to normality tests and 1-way ANOVA. No significant statistical differences were found among the groups, indicating that the different try-in materials had similar effects on the color of the ceramic laminates.

Facetas cerâmicas: como remover os excessos do cimento resinoso? / Ceramic veneers: removing the excesses of the resin cement?

Recomendamos para a cimentação de restaurações cerâmicas parciais do tipo facetas, os cimentos resinosos fotoativados escoam nas margens pós-assentamento das peças cerâmicas nos substratos dentários. O escoamento resulta na formação de excessos marginais de cimento, que devem ser removidos adequadamente, pois comprometem o resultado estético, a saúde periodontal e a longevidade do processo reabilitador. O objetivo deste artigo é apresentar um caso clínico detalhando a etapa de cimentação, com foco na remoção de excessos do cimento resinoso, e apresentar ilustrações de micrografias em Microscopia Eletrônica de Varredura (MEV) sobre duas diferentes técnicas de remoção de excessos do cimento resinoso. Conclui que a técnica de pincel para remoção de excesso de cimento resinoso é a melhor opção para a rotina clínica, tendo em vista seus bons resultados e simplicidade técnica

Recommended for cementation of Partial Ceramics Restorations Veneer-type, photoactivated resin cements seep into the margins of post-settlement of the dental ceramic substrates. The flow results in the formation of a marginal cement excesses that must be properly removed as it may compromise the aesthetic result, periodontal health and longevity of the rehabilitation process. The purpose of this paper is to present a case detailing the cementing step, focused on removal of the excess resin cement and display Scanning Electron Microscopy (SEM) micrographs on two different techniques for excess removal of the resin cement. It was concluded that the brush technique is the best option for excess removal of the resin cement for the clinical routine, motivated by the good results and technical simplicity

Influence of activation mode of resin cement on the shade of porcelain veneers.

PURPOSE: The aim of this study was to evaluate the influence of resin luting cement's activation mode in the final shade of porcelain veneers after accelerated artificial aging (AAA). MATERIALS AND METHODS: Porcelain veneers (IPS Empress Esthetic) were produced using a standardized shade (ET1) and thickness (0.6 mm). Twenty bovine teeth were collected, prepared, and divided into two groups: group I (n = 10)-light-cured group, only base paste was applied to the veneers; group II (n = 10)-dual-cured group, in which the same base paste used in group I and a transparent catalyst were proportionally mixed for 20 seconds and then applied to the veneers. The specimens were light-cured for 60 seconds each and were next subjected to AAA. They were submitted to color readings with a spectrophotometer in three instances: in the tooth surface (only the substrate), after the cementation and polymerization of the veneers, and after the AAA. The values of L*, a*, and b* were obtained and the total color change was calculated (∆E*). Values obtained were subjected to statistical analysis, with a significance of 0.05. RESULTS: There were no significant differences between dual- and light-cured modes considering ∆E*, L*, a*, and b* values obtained after aging (p > 0.05). Within the dual-cured mode there were no significant differences in ∆E*, L*, a*, and b* values (p > 0.05). CONCLUSION: No relevant differences were found between the two activation modes in color change. When submitted to aging, dual- and light-cured modes of the resin cement showed visually perceptible (∆E* > 1.0) color changes; however, within the threshold of clinical acceptance (∆E* > 3.3).

Effect of light source and solvent on the sorption and solubility of two dual-cured cements photocured through ceramic.

The purpose of this study was to verify the polymerization efficiency of two curing units through a ceramic barrier. Forty specimens apiece of two resin luting cements (AllCem and RelyX U100) were made in a stainless steel mold. The experimental group was photocured through a ceramic barrier, while the control group was photocured without a barrier. The specimens were stored in deionized water or 75% ethanol for 28 days and submitted to tests of sorption and solubility (ISO 4049:2000). Values obtained were subjected to ANOVA and Tukey multiple comparison tests (P < 0.05). RelyX U100 suffered more sorption and solubility than AllCem. The light sources did not influence sorption and solubility values, except for the specimens of RelyX U100 that were photocured with an LED unit through ceramic and stored in ethanol; these specimens demonstrated higher values than those photocured using a halogen lamp.