Longevidade clínica das restaurações de resina composta sonificadas e não sonificadas em dentes permanentes posteriores: revisão sistemática e meta-análise / Clinical longevity of sonicated and non-sonicated composite resin restorations on posterior permanent teeth: a systematic review and meta-analysis

Resinas compostas são materiais dentários amplamente utilizados em restaurações diretas na Odontologia. A aplicação da energia sônica na sua técnica restauradora tem sido uma opção para diminuir as consequências das suas tensões de polimerização. O objetivo desse estudo foi avaliar a longevidade clínica de restaurações Classe I e II em resina composta com e sem o uso da energia sônica, através de uma revisão sistemática da literatura e meta-análise. Uma busca sistemática foi realizada nas seguintes bases de dados: PubMed, Biblioteca Cochrane, Web of Science, Scopus, LILACS, BBO e a Literatura Cinzenta sem restrições de idioma ou ano de publicação. Após a remoção das duplicatas foram identificados 5485 estudos. Dezesseis cumpriram os critérios de inclusão após a triagem de resumos. Não foram incluídos artigos após a busca manual da lista de referência dos estudos incluídos. A qualificação do risco de viés foi realizada pelo RoB da Colaboração Cochrane para os estudos randomizados e ROBINS-I para os ensaios clínicos controlados não randomizados. A meta-análise foi realizada utilizando o software RevMan, sendo analisado o número de restaurações com scores UDHS alfa. A heterogeneidade foi avaliada pelo índice I2, com significância definida em p <0,05. Quatro estudos clínicos foram incluídos na análise qualitativa, sendo dois RCTs e dois ensaios clínicos controlados e apresentaram respectivamente moderado e baixo risco de viés. Não foi observada diferença estatística na longevidade das restaurações com o uso da energia da sônica em dentes permanentes (p>0,05), nos critérios avaliados: forma anatômica (IC=1.05[0.95,1.15]; I²=0%; p=0.37); estabilidade de cor (IC=1.02[0.93,1.13, I²=0%, p=0.65); adaptação marginal (IC=1.05[0.95,1.16]; I²=0%; p=0.38); sensibilidade pós-operatória (IC=1.01[0.93,1.10]; I²=0%; p=0.80); cáries secundárias (IC=1.01[0.93,1.10]; I²=0%; p=0.80); descoloração marginal (IC=1.05[0.95,1.16]; I²=0%; p=0.38), rugosidade superficial (IC=1.09[0.97,1.23]; I²=19%; p=0.14) e retenção (IC=1.00[1.91,1.10] I²=0% p=1.00). Com base nos resultados obtidos, não houve diferença na longevidade de restaurações diretas de resina composta com e sem o uso da energia sônica, independente da técnica e do dente restaurado. Significado clínico: A odontologia busca avanços tecnológicos para otimizar a prática clínica dos profissionais e evoluir quanto aos materiais dentários. A indicação de uma técnica restauradora com o uso de novas tecnologias levanta questões sobre a longevidade das restaurações realizadas em comparação a técnicas já sedimentadas na literatura. Estudos in vitro não são capazes de responder esse questionamento, mas a compilação de ensaios clínicos traz uma previsibilidade quanto aos resultados esperados. Através dos resultados obtidos, concluiu-se que não há diferenças estatísticas significativas na longevidade das restaurações em resina composta com e sem o uso da energia sônica. Dessa forma, o estudo esclareceu essa dúvida. (AU)

Composite resins are dental materials widely used in direct restorations in dentistry. The application of sonic energy in its restorative technique has been an option to reduce the consequences of its polymerization stresses in reducing the consequences of its polymerization shrinkage stresses. The objective of this study was to evaluate the clinical longevity of Class I and II restorations in composite resin with and without the use of sonic energy, through a systematic review of the literature and meta-analysis. Searches were conducted on PubMed, Cochrane Library, Web of Science, Scopus, LILACS, BBO and Gray Literature without language restrictions or year of publication. After removing duplicates, 5485 studies were identified. Sixteen met the inclusion criteria after screening abstracts. Articles were not included after manual search of the reference list of the included studies. The qualification of the risk of bias was carried out by the Cochrane Collaboration for randomized studies and ROBINS-I for controlled clinical trials. The meta-analysis was performed using RevMan software, analyzing the number of restorations with alpha UDHS scores. Heterogeneity was assessed using the I² index, with significance set at p<0.05. Four clinical studies were included in the qualitative analysis, two RCTs and two controlled clinical trials, showed, respectively, moderate and low risk of bias. No statistical difference was observed in the longevity of restorations with the use of sonic energy in permanent teeth (p> 0.05), in the evaluated criteria: anatomical shape (CI = 1.05 [0.95,1.15]; I²= 0%; p = 0.37); color stability (CI = 1.02 [0.93,1.13, I² = 0%, p = 0.65); marginal adaptation (CI = 1.05 [0.95,1.16]; I² = 0%; p = 0.38); postoperative sensitivity (CI = 1.01 [0.93,1.10]; I²= 0%; p = 0.80); secondary caries (CI = 1.01 [0.93,1.10]; I² = 0%; p = 0.80); marginal discoloration (CI =1.05 [0.95,1.16]; I² = 0%; p = 0.38), surface texture (CI = 1.09) [0.97,1.23]; I² = 19%; p = 0.14) and retention (CI=1.00[1.91,1.10]; I²=0% p=1.00). Based on the results obtained, there was no difference in the longevity of direct composite resin restorations with and without the use of sonic energy, regardless of the technique and the restored tooth. Clinical significance: Dentistry seeks technological advances to optimize the clinical practice of professionals and evolve in terms of dental materials. The indication of a restorative technique with the use of new technologies raises questions about the longevity of the restorations performed in comparison to techniques already established in literature. In vitro studies are not able to answer this question, but the compilation of clinical trials provides predictability of the expected results. Therefore, this study clarified that doubt.

Multiobjective Optimization of Fabrication Parameters of Jute Fiber/Polyester Composites with Egg Shell Powder and Nanoclay Filler.

In the present study, a model is presented to optimize the fabrication parameters of natural fiber reinforced polyester matrix composites with dual fillers. In particular, jute fiber mat was chosen as reinforcement and eggshell powder (ESP) and montmorillonite nanoclay (NC) were selected as fillers. The weight per square meter (GSM) of the fiber, the weight percentage of ESP and NC have been chosen as independent variables and the influence of these variables on tensile, flexural and impact strength of the composite has been inspected. The permutations of the different combinations of factors are intended to accomplish higher interfacial strength with the lowest possible number of tested specimens. The experiments were designed by the Taguchi strategy and a novel multi-objective optimization technique named COPRAS (COmplex PRoportional ASsessment of alternatives) was used to determine the optimal parameter combinations. Affirmation tests were performed with the optimal parameter settings and the mechanical properties were evaluated and compared. Experimental results show that fiber GSM and eggshell powder content are significant variables that improve mechanical strength, while the nanoclay appears less important.

Influência do uso do silano na resistência de união e no padrão de fratura nos reparos da resina indireta Ceramage com a resina direta Filtek Z350 / Influence of silane on bond strength and fracture pattern for indirect resin Ceramage repair with direct resin Filtek Z350

Pouca informação encontra-se disponível sobre a influência dos diferentes tratamentos de superfície das restaurações de resina indireta na resistência de união com as resinas diretas usadas para reparo. O objetivo deste estudo foi avaliar a influência de diferentes técnicas com uso do silano no reparo da resina indireta Ceramage na resistência ao cisalhamento e no padrão de fratura com a resina composta direta Filtek Z350. Blocos de resina composta indireta Ceramage (SHOFU) foram confeccionados e envelhecidos por 3 semanas em água destilada à 37°C. Posteriormente, foram jateados com óxido de alumínio e distribuídos aleatoriamente em 4 grupos de 10. No grupo 1, a superfície da resina Ceramage recebeu o adesivo convencional Adper Single Bond 2 (3M ESPE). No grupo 2 foi aplicado adesivo universal Adper Single Bond Universal (3M ESPE). Nos grupos 3 e 4, foi feita a aplicação do silano Silano Mais (Dentsply Sirona) e dos adesivos convencional e universal respectivamente. Foram confeccionados cilindros de resina composta direta Filtek Z350 (3M ESPE) na superfície da resina indireta Ceramage em todos os espécimes. Em seguida foi feito o teste de cisalhamento na máquina de teste universal (EMIC) após o armazenamento dos espécimes em água destilada à 37°C por 24 horas. O estereomicroscópio foi utilizado para analisar as falhas. A análise estatística foi feita pelo teste estatístico de Kruskal-Wallis. Não houve uma diferença estatisticamente significativa (p>0,05) na resistência de união e no padrão de fratura entre as diferentes técnicas de aplicação do silano no tratamento de superfície. Concluiu-se que o uso do silano pode não ser imprescindível para aumentar a resistência de união do reparo da resina indireta Ceramage com a resina direta Filtek Z350. No entanto, clinicamente é provável que se tenha uma maior chance de sucesso no reparo com a aplicação do silano. (AU)

Just few information is available about the influence of different surface treatments of indirect resin restorations on bond strength to direct resins used for repair. The objective of this study was to evaluate the influence of different techniques with the use of silane on the shear bond strength and fracture pattern of indirect resin Ceramage to Filtek Z350 direct composite resin. Ceramage indirect composite blocks (SHOFU) were made and aged in distilled water at 37 ° C for 3 weeks. Subsequently, they were sandblasted with aluminum oxide and randomly divided into 4 groups of 10. In group 1, the surface of the Ceramage resin received the conventional adhesive Adper Single Bond 2 (3M ESPE). In group 2, Adper Universal Bond universal adhesive (3M ESPE) was applied. In groups 3 and 4, the Silano Mais silane (Dentsply Sirona) and the conventional and universal adhesives were applied respectively. Composite resins cylinder of Filtek Z350 (3M ESPE) were made on the surface of the indirect resin Ceramage in all specimens. The shear test was then performed on the universal test machine (EMIC) after their storage in destilled water at 37°C for 24 hours. The stereomicroscope was used to analyze the fractures. Statistical analysis was done by Kruskal-Wallis test. There were no statistically significant differences (p>0,05) in bond strength values and in fracture pattern between the different techniques of application of silane in surface treatment. It was concluded that the silane coupling agent would not be necessary for repairing indirect resin Ceramage with composte resin Filtek Z350. However, clinically it is likely to have a better chance of successful repair with silane application. (AU)

Formação de fendas em restaurações de resina composta: polimento imediato versus tardio / Gap formation in composite resin restorations: immediate versus late polishing

O objetivo deste estudo foi avaliar a influência do momento da etapa de polimento, imediato ou após sete dias, na formação de fendas em restaurações de resina composta. Cavidades cilíndricas foram preparadas nas superfícies vestibulares de incisivos bovinos. Cada cavidade foi hibridizada com um dos dois sistemas adesivos: convencional (Adper Single Bond 2) ou autocondicionante (Single Bond Universal), e restaurada usando uma das três resinas compostas: nanoparticulada (Z350), micro-híbrida (P60) e bulk-fill (ONE). As cavidades restauradas foram divididas em dois subgrupos de acordo com o tempo de polimento, imediato ou postergado por 7 dias após a restauração. Por meio da combinação dos sistemas adesivos, resinas compostas e tempos de polimento, foram criados 12 grupos (n = 5). As porcentagens de fendas marginais (%FM) foram avaliadas quantitativamente com o microscópio confocal de varredura a laser. O módulo de elasticidade das resinas compostas foi obtido por meio do teste de flexão em três pontos. Os dados foram analisados por análise de variância e pelo teste de Tukey's HDS (α = 0,05). Em relação ao sistema adesivo, a %FM foi estatisticamente maior para as cavidades restauradas com Single Bond Universal (p<0,05). Com relação às resinas compostas, o resultado foi o seguinte: P60 > ONE > Z350 (p<0,05). O tempo de polimento imediato apresentou %FM estatisticamente menor que o tardio (p<0,05). P60 apresentou o maior módulo de elasticidade (p<0,05). Foi possível concluir que o polimento imediato gera menor formação de fendas em restaurações de resina composta. (AU)

The aim of this study was to analyze the influence of the polishing time, immediately or after seven days, in gap formation in composite resin restorations. Cylindrical cavities were prepared on buccal surfaces of bovine incisors. Each cavity was hybridized with one of the two adhesive systems: etch-and-rinse (Adper Single Bond 2) and self-etching (Single Bond Universal), and restored using one of the three composite resins: nanofilled (Z350), minifilled hybrid (P60) and bulk-fill (ONE). The cavities restored were divided in two subgroups according to polishing time, immediately or delayed by 7 days after specimen restoration. Through the combination of the adhesive systems, composite resins and polishing times, 12 groups were created (n=5). Percentages of marginal gaps (%MG) were quantitatively assessed with confocal laser scanning microscope. The flexural modulus of the composite resins was obtained from bar-shaped specimens submitted to three-point bending test. The data were analyzed by three-way ANOVA and Tukey's HSD test (α=0.05). Regarding adhesive system, %MG was statistically higher for cavities restored with Single Bond Universal (p<0.05). With respect to composite resins, the result was as follow: P60 > One > Z350 (p<0.05). Immediate polishing time presented statistically lower %MG than delayed one (p<0.05). P60 presented the highest flexural modulus (p<0.05). It was possible to conclude that immediate polishing generates less gap formation in composite resin restorations. (AU)

Optimizing quality and safety of dental materials.

This paper discusses aspects of quality and safety improvement of the most commonly used dental restorative materials, the resin-based composites. From a patient's perspective, long-lasting resin-based restorations without complications are important. Recurrent caries and fracture are the most common causes for restoration failures. Proper handling and curing of the composites improve the mechanical properties of the restorations and increase safety by reducing exposure to residual methacrylate monomers. A number of compounds have been introduced in restorative materials to reduce the risk of recurrent caries, even though a real breakthrough has not yet been achieved. It is concluded that simple measures may improve the quality and safety of resin-based composite restorations.

Original and Repair Bulk Fracture Resistance of Particle Filler and Short Fiber-Reinforced Composites.

OBJECTIVE: This study aimed to evaluate the original (OR) and repair (RR) fracture resistance of a semi-interpenetrating polymer network (semi-IPN)-based short fiber-reinforced composite compared to dimethacrylate-based composite materials by means of the V-notch test. METHODS AND MATERIALS: Circular specimens (5×2 mm) with a centrally machined 90° V-shaped notch were prepared. Four bulk fill (Filtek Bulk Fill, Venus Bulk Fill, TetricEvo Ceram Bulk Fill, SDR), three microfilled hybrid (GC-Anterior, GC-Posterior, Z250), one nanofilled (SupremeXTE), and two short fiber-reinforced (Alert, everX Posterior) composites were selected. EverX Posterior was the semi-IPN material. Specimens (n=12/group) were either dry or water stored for 7 and 30 days, respectively, at 37°C and then loaded in two-point load until fracture. One-half of each tested specimen was used for the repair procedure. Repairing surfaces were diamond-bur ground, etched, and treated with silane containing universal adhesive (Scotchbond Universal) before repair. RESULTS: Three-way analysis of variance revealed a significant statistical difference between the groups ( p<0.05). The fracture resistance of dry-stored groups was greater than that of water-stored groups. The highest OR was observed for dry-stored Alert (23.4 N/mm), which significantly deteriorated in water (17.4 N/mm) ( p<0.05). The highest RR was observed for everX Posterior (20.0 N/mm), which did not deteriorate in water significantly (19.0 N/mm) ( p>0.05). The everX Posterior preserved the specimens' integrity at the final fracture load (ductile fracture), whereas all other materials fractured into two halves at the interface (adhesive failure). CONCLUSIONS: The only material that provided enhanced repair strength that was close to the original cohesive strength of the material was everX Posterior. The endurance of repaired restorations can be improved by using semi-IPN-based filling material.

Dynamic and Static Flexural Appraisal of Resin-based Composites: Comparison of the ISO and Mini-flexural Tests.

The objective of this study was to determine the influence of specimen dimension and conditioning medium on the dynamic and static flexural properties of resin-based composites (RBCs). One conventional (Filtek Z350) and two bulk-fill RBCs (Filtek Bulk-fill and Beautifil-Bulk Restorative) were evaluated. Bar-shaped specimens with dimensions 25 × 2 × 2 mm (ISO flexural [IFT]) or 12 × 2 × 2 mm (mini-flexural [MFT]) were fabricated using customized stainless-steel molds, finished, measured, randomly divided into two groups, and conditioned in air or artificial saliva (SAGF) for seven days at 37°C. The specimens (n=10) were then subjected to dynamic and static three-point flexural testing. Data for storage modulus, loss modulus, loss tangent, flexural strength, and modulus were computed and subjected to t-test, analysis of variance/Tukey test, and Pearson correlation at a significance level of α = 0.05. For both IFT and MFT, significant differences in dynamic and static flexural properties were more prevalent between materials after storage in saliva. For both conditioning mediums, the strongest correlation between IFT and MFT was observed for flexural strength. While significant positive correlations were observed for all flexural properties with saliva, no significant correlations were detected for loss tangent and flexural modulus with air. For both IFT and MFT, storage in saliva appeared to be more discriminative than storage in air. As moderate to strong positive relationships exist between IFT and MFT for dynamic and static flexural properties, the mini-flexural test holds promise as a replacement for the ISO 4049 in view of its clinical relevance and greater efficiency.

OCT for early quality evaluation of tooth-composite bond in clinical trials.

OBJECTIVES: To evaluate early quality of composite restorations with a universal adhesive in different application modes clinically and with optical coherence tomography (OCT). METHODS: 22 patients with four non-carious cervical lesions each received composite restorations (Filtek Supreme™ XTE, 3 M). The universal adhesive Scotchbond Universal™(SBU, 3 M) was applied with three etching protocols: self-etch (SE), selective-enamel-etch (SEE) and etch-and-rinse (ER). The etch-and-rinse adhesive OptiBond™ FL (OFL, Kerr) served as a control. Restorations were imaged by OCT (Thorlabs) directly after application (t0). After 14 days (t1) and 6 month (t2) OCT imaging (interfacial adhesive defects) was repeated combined with clinical assessment (FDI criteria). Groups were compared by Friedman-/Wilcoxon- and McNemar-Test. RESULTS: No differences were seen clinically between groups (pi ≥ 0.500). OCT assessment revealed more adhesive defects at the enamel interface with SBU/SE at t0-t2 compared to all groups (pi ≤ 0.016). OFL showed more defects than SBU/ER (t1: p = 0.01; t2: p = 0.083). At dentin/cementum interface OFL exhibited more adhesive defects than SBU with all conditioning modes (t0, t1, pi ≤ 0.003) and at t2 to SBU/SE and SBU/ER (p < 0.001). Since t1 defects with SBU were detected more frequently in the SE and SEE modes compared to ER (pi ≤ 0.037). In contrast to SBU defects increased with OFL up to t2 (pi ≤ 0.007). CONCLUSIONS: In contrast to clinical evaluation, OCT revealed subtle adhesive defects directly after application that might interfere with clinical success. It was demonstrated that ER does not decrease initial adhesion of SBU to dentin.

Effects of core-to-dentin thickness ratio on the biaxial flexural strength, reliability, and fracture mode of bilayered materials of zirconia core (Y-TZP) and veneer indirect composite resins.

STATEMENT OF PROBLEM: Indirect composite resins (ICR) are promising alternatives as veneering materials for zirconia frameworks. The effects of core-to-dentin thickness ratio (C/Dtr) on the mechanical property of bilayered veneer ICR/yttria-tetragonal zirconia polycrystalline (Y-TZP) core disks have not been previously studied. PURPOSE: The purpose of this in vitro study was to assess the effects of C/Dtr on the biaxial flexural strength, reliability, and fracture mode of bilayered veneer ICR/ Y-TZP core disks. MATERIAL AND METHODS: A total of 180 bilayered 0.6-mm-thick composite resin disks in core material and C/Dtr of 2:1, 1:1, and 1:2 were tested with either core material placed up or placed down for piston-on-3-ball biaxial flexural strength. The mean biaxial flexural strength, Weibull modulus, and fracture mode were measured to evaluate the variation trend of the biaxial flexural strength, reliability, and fracture mode of the bilayered disks with various C/Dtr. One-way analysis of variance (ANOVA) and chi-square tests were used to evaluate the variation tendency of fracture mode with the C/Dtr or material placed down during testing (α=.05). Light microscopy was used to identify the fracture mode. RESULTS: The mean biaxial flexural strength and reliability improved with the increase in C/Dtr when specimens were tested with the core material either up and down, and depended on the materials that were placed down during testing. The rates of delamination, Hertzian cone cracks, subcritical radial cracks, and number of fracture fragments partially depended on the C/Dtr and the materials that were placed down during testing. CONCLUSION: The biaxial flexural strength, reliability, and fracture mode in bilayered structures of Y-TZP core and veneer ICR depend on both the C/Dtr and the material that was placed down during testing.

Clinical performance of aesthetic restorative materials in primary teeth according to the FDI criteria.

AIM: The purpose of this study is to evaluate the clinical performance of three different restorative materials in primary teeth according to the FDI criteria. MATERIALS AND METHODS: Resin-modified glass ionomer cement, compomer and composite resin restorations (n=93) were made in 31 patients. The restorations were clinically evaluated at baseline, 6th, 12th and 18th month with the FDI criteria. RESULTS: The cumulative survival rate after 18 months was found to be 90.3% for resin modified glass ionomer cement restorations, 100% for compomer restorations and 80.6% for composite resin restorations. Statistically significant increase in surface roughness, colour mismatch, anatomic form loss and marginal deterioration were detected in resin- modified glass ionomer group (p<0.05). The most frequent reason for restoration failure in composite resin group was restoration fractures. CONCLUSIONS: The resin-modified glass ionomer restorations necessitates close follow-up because of the risk of increase in surface roughness, changes in colour and loss in anatomic form and marginal adaptation. The clinical performance of compomer restorations is superior to resin-modified glass ionomer and composite resin restorations in primary teeth.

Fechamento de diastema com resina composta direta: relato de caso clínico / Diastema closure with direct composite restorations: a case report

Com a evolução dos materiais restauradores adesivos diretos e das técnicas restauradoras minimamente invasivas, é possível realizar o fechamento de diastemas inter incisivos superiores de maneira efetiva e estética em uma única sessão. O presente trabalho consiste em um relato de caso clínico que aborda o clareamento dental e o fechamento de diastema entre os dentes 11 e 21 de um paciente jovem. Previamente ao procedimento restaurador foi realizado clareamento de consultório em todos os dentes com peróxido de hidrogênio 35%. Então, o planejamento restaurador foi auxiliado por modelos de estudo associado ao enceramento diagnóstico.A técnica restauradora de eleição foi a resina composta direta com o auxílio de uma matriz/guia de silicona para a confecção das faces palatinas das restaurações. Após o acabamento e polimento, obteve-se a reanatomização dos incisivos centrais com a eliminação do diastema. O tratamento realizado baseado no clareamento dental seguido por restaurações diretas de resina composta foi eficaz na solução estética do sorriso, atingindo a expectativa do paciente e dentro dos princípios de máxima preservação dos tecidos dentais.

After the evolution of restorative adhesive materials and minimal invasive restorations, it ispossible to close a maxilar interincisal diastema in an effective and aesthetical way, performingit in only one session. This clinical case report approaches a teeth bleaching and diastema closurewith composites between teeth 11 and 21, of a young male patient. The elective restorative technique was direct composite restoration with a silicon putty matrix to make the shape of thelingual surfaces of the restorations. Before the restoration procedure, it was performed “in office”bleaching technique, in addition to the case planning with the assistance of a wax-up. The tooth whitening therapy followed by direct composite restorations was effective, contributing to clinical success, esthetic and patient´s satisfaction.

Relation between conversion degree and cytotoxicity of a flowable bulk-fill and three conventional flowable resin-composites.

OBJECTIVE: The aim of this study is to evaluate if the cytotoxic effects of the Surefil SDR flow, bulk fill flowable composite resin and three conventional flowable materials (Venus Diamond Flow, Filtex Supreme XTE Flowable and Enamel plus HRi Flow) correlated with the conversion degree (DC); hardness and depth of cure are also assessed. MATERIALS AND METHODS: Disks of each materials--cured using LED lamp--are utilized to evaluate DC (by FT-IR technique), amount of leached monomers (by HPLC technique), hardness (by Vickers hardness tester) and cytotoxicity (by MTT test). RESULTS: All tested materials show light cytotoxic effects, independently from DC values. Both the latter parameter and the hardness, in fact, change in function of thickness and type of material. HPLC results show that the monomers amount leached from each specimen is influenced by thickness but it is always very low which justifies the absence of any cytotoxic effect. CONCLUSIONS: Our findings suggest that there are not statistically significant differences in cytotoxicity in all experimental conditions, notwithstanding the differences in hardness and in degree of conversion.

Comportamiento del color de discos y restauraciones en resina compuesta sometidos a altas temperatura con fines forenses / Performance of color of discs and restorations in composite resin subject to high temperatures to forensic purposes

El objetivo de este estudio fue determinar el comportamiento del color de discos y restauraciones en resina compuesta sometidos a altas temperaturas con fines forenses. Para ello se realizó un estudio descriptivo de naturaleza pseudoexperimental in vitro que describió los cambios colorimétricos que ocurrieron en 75 discos y 75 dientes restaurados en resina compuesta (Z100 3M-ESPE®), confeccionados en cinco colores (A1, A2, A3, A3.5 y B2), al ser sometidos a la acción de altas temperaturas, con el propósito de establecer parámetros cualitativos a partir del cambio de color de utilidad forense. Los resultados obtenidos permitieron explicar los cambios de color por espectrometría, de tal forma que una resina compuesta, a 200 oC, pierde brillo y matiz; a 400 oC, pierde brillo, matiz y saturación; y a 600 oC, 800 oC y 1.000 oC gana brillo y pierde matiz y saturación. Así, no existieron diferencias significativas en las coordenadas de color L* a* b* al comparar los discos con los dientes restaurados. En conclusión, la interpretación visual del cambio de color y las coordenadas de color L* a* b* a través del uso de un espectrofotómetro puede constituirse en un método comparativo de bajo costo y de aplicación forense al momento de identificar el tipo y el color de un material restaurador en un cadáver o en restos humanos quemados, carbonizados o incinerados, para obtener marcadores positivos durante el cotejo ante mórtem-post mórtem, y estimar la temperatura máxima alcanzada durante la exposición (AU)

The objective for this study was to determine the color behavior of discs and composite resin restorations subjected to high temperature for forensic purposes. For this, a descriptive study of pseudo-experimental nature was made, to describing in vitro colorimetric changes that occur on the surface of 75 disks and 75 class I composite resin restorations (Z100 3M-ESPE®) made in five colors (A1, A2 , A3, A3.5 and B2), when subjected to the action of high temperatures (200 oC, 400 oC, 600 oC, 800 oC y 1,000 oC); in order to set parameters from the color change that can be applied to the forensic dental identification methods in the case of bodies or human remains burnt, charred or incinerated. The color changes can be explained by spectrometry. A composite resin subjected to 200 oC loses brightness and hue; to 400 oC wins brightness, hue and saturation; to 600 oC, 800 oC and 1,000 oC lost brightness, hue and saturation. No significant differences in the color coordinates L * a * b * to compare discs with the restored teeth, so the test bodies were suitable to test with the commercial composite resin system ESPE® 3M-Z100. In conclusion, the visual interpretation of color change and the L * a * b * color coordinates through the use of a spectrometer becomes a comparative forensic method application inexpensive when identifying the type and color a restorative material in a human remains burnt, charred or incinerated, to obtain positive markers for the antemortem-postmortem comparison and estimate the maximum temperature reached (AU)

A new methodology for fluorescence analysis of composite resins used in anterior direct restorations.

The aim of this study was to use a new methodology to evaluate the fluorescence of composite resins for direct restorations. Microhybrid (group 1, Amelogen; group 2, Opallis; group 3, Filtek Z250) and nanohybrid (group 4, Filtek Z350 XT; group 5, Brilliant NG; group 6, Evolu-X) composite resins were analyzed in this study. A prefabricated matrix was used to prepare 60 specimens of 7.0 × 3.0 mm (n = 10 per group); the composite resin discs were prepared in 2 increments (1.5 mm each) and photocured for 20 seconds. To establish a control group of natural teeth, 10 maxillary central incisor crowns were horizontally sectioned to create 10 discs of dentin and enamel tissues with the same dimensions as the composite resin specimens. The specimens were placed in a box with ultraviolet light, and photographs were taken. Aperture 3.0 software was used to quantify the central portion of the image of each specimen in shades of red (R), green (G), and blue (B) of the RGB color space. The brighter the B shade in the evaluated area of the image, the greater the fluorescence shown by the specimen. One-way analysis of variance revealed significant differences between the groups. The fluorescence achieved in group 1 was statistically similar to that of the control group and significantly different from those of the other groups (Bonferroni test). Groups 3 and 4 had the lowest fluorescence values, which were significantly different from those of the other groups. According to the results of this study, neither the size nor the amount of inorganic particles in the evaluated composite resin materials predicts if the material will exhibit good fluorescence.

Depth of cure of bulk-fill flowable composite resins.

In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

Dental students' ability to assess their performance in a preclinical restorative course: comparison of students' and faculty members' assessments.

Dental education consists of both theoretical and practical learning for students to develop competence in treating patients clinically. When dental students encounter practical courses in their first year as a new educational experience, they must also learn to evaluate themselves. Self-evaluation is an essential skill to learn for dental professionals to keep increasing their competence over the course of their careers. The aim of this study was to compare the assessment scores of second- and third-year dental students and the faculty in two consecutive preclinical practical exams in restorative dentistry courses in a dental school in Turkey. Faculty- and student-assigned scores were calculated from two consecutive preclinical examinations on tooth restorations performed on both artificial casts and phantom patients. The students were formally instructed on grading procedures for tooth preparations, base and restoration placement, and polishing criteria. After each step, each item was assessed by faculty members, the student, and another student. The results indicated that the initial differences between second-year students' assessments of their own preclinical practical ability and that of the faculty decreased among the third-year students. Self-evaluation scores did not indicate whether the third-year students tended to over- or underestimate the quality of their own work. However, the second-year students not only overestimated themselves but thought they were above average. The results point to the need to develop students' self-insight with more exercises and practical training.

Evaluation of the bond strengths of 3 endodontic cements via push-out test.

In this study, the push-out method was used to evaluate the bond strengths of 3 types of endodontic cements according to their composite base: methacrylate, epoxy resin, and an experimental copaiba oil resin. The study hypothesis was that the methacrylate-based and experimental cements would have bond strengths equal to or greater than that of the epoxy resin-based cement. Thirty bovine tooth roots, 18 mm long, were divided into 3 groups (n = 10) based on the chosen cement treatment. After treatment, the specimens were sectioned and submitted to a push-out test. Results showed that there was no statistically significant difference (P < 0.05) between the cements used or between the middle and apical thirds of the roots. It could be concluded that the tested cements had satisfactory and similar bond strengths to dentin.

Low-shrinkage composites: an in vitro evaluation of sealing ability after occlusal loading.

The objective of this in vitro study was to compare the microleakage of a flowable low-shrinkage-stress resin composite--in a Class II fatigue-loading design when used as a 4 mm dentin replacement--to a conventionally layered silorane-based resin composite. Eighty standardized 4 mm deep cavities, divided into 4 subgroups, were restored with the 2 tested materials. Half of the restorations were submitted to mechanical loading, and all of the restorations were prepared for microleakage evaluation. The evaluation of the marginal adaptation to dentin was performed with scanning electron microscopy. The results showed that both silorane-based composite groups had higher rates of microleakage in comparison to the low-shrinkage-stress resin composite groups.

Fracture of fiber-reinforced composites analyzed via acoustic emission.

This study investigated the fracture resistance of composite resins using a three-point bending test and acoustic emission (AE) analysis. Three groups of specimens (n=15) were prepared: non-reinforced BelleGlass HP composite (NRC), unidirectional (UFRC) and multidirectional (MFRC) fiber-reinforced groups which respectively incorporated unidirectional Stick and multidirectional StickNet fibers. Specimens were loaded to failure in a universal testing machine while an AE system was used to detect audible signals. Initial fracture strengths and AE amplitudes were significantly lower than those at final fracture in all groups (p<0.05). Initial fracture strength of UFRC (170.0 MPa) was significantly higher than MFRC (124.6 MPa) and NRC (87.9 MPa). Final fracture strength of UFRC (198.1 MPa) was also significantly higher than MFRC (151.0 MPa) and NRC (109.2 MPa). Initial and final fracture strengths were significantly correlated (r=0.971). It was concluded that fiber reinforcement improved the fracture resistance of composite resin materials and the monitoring of acoustic signals revealed significant information regarding the fracture process.