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OBJECTIVES: to evaluate the quality and stability of adhesive interfaces established by self-etching adhesives on caries-affected primary dentin (CAD) treated with glutaraldehyde (GA) or silver diamine fluoride (SDF). METHODS: 42 primary molars were exposed to a microbiological caries-inducing protocol and divided into 6 groups according to the adhesive system (Clearfil SE - CL or FL Bond II - FL) and pretreatment (water, GA or SDF) applied on CAD. One tooth from each group was analyzed for surface modification using infrared spectroscopy. Crowns were restored with resin composite (n = 36) and cut into beams and slices. The beams were subjected to microtensile testing, Raman spectroscopy and SEM after 24 h and 6 months of storage. The slices were analyzed using Micro-Raman spectroscopy to determine the diffusion zone thickness (DZ) in each period. Data were analyzed by ANOVA and Tukey or Kruskal-Wallis and Dunn tests (α = 0.05%). RESULTS: SDF reduced the immediate bond strength for both adhesives. The control groups showed a decrease in BS after 6 months in artificial saliva. GA increased immediate DZ for FL, while SDF had the opposite effect on CL. GA decreased the DZ for FL at 6 months. There was a predominance of adhesive failures with areas of cohesive dentin fractures within control groups. SIGNIFICANCE: Modifications caused by dentin surface treatments may directly affect the performance of adhesive systems and the quality and stability of adhesive restorations.

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OBJECTIVE: This systematic review aimed to analyze if using polywave light-emitting diodes (LED) to photoactivate resin-based materials (resin composites, adhesive systems, and resin cements) containing alternative photoinitiators provide better physicochemical properties than monowave ones. MATERIAL AND METHODS: Inclusion criteria were in vitro studies that evaluated the degree of conversion, microhardness and flexural strength in resin-based materials containing alternative photoinitiators and light-activated with mono and polywave LEDs. Exclusion criteria were studies that evaluated the physicochemical properties of composites through any material interposed between the LED and the resin composite and studies that exclusively compared different modes and/or light activation times. Selection of studies, data extraction, and risk-of-bias analysis was performed. Data from selected studies were qualitatively analyzed. A systematic search was performed in June 2021 using PubMed/Medline, Embase, Scopus, and ISI Web of Science databases and grey literature without language restriction. RESULTS: A total of 18 studies were included in the qualitative analysis. Nine studies used diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as an alternative photoinitiator for resin composite. Polywave LED improved the degree of conversion of resin composite compared to monowave in 9 of the included studies. Polywave LED improved the microhardness of resin composite compared to monowave in 7 of the included studies. Polywave LED improved the degree of conversion for 11 studies and microhardness of resin composite compared to monowave for 7 included studies. No differences in the flexural strength medium between poly and monowave LEDs were observed. The evidence was graded as low quality due to the high risk of bias for 11 studies. CONCLUSION: The existing studies, with their limitations, revealed that the polywave light-emitting diode maximizes activation, resulting in a higher degree of double-bond conversion and microhardness of resin composites containing alternative photoinitiators. However, the flexural strength of these materials is not influenced by the type of light activation device.

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BACKGROUND: Idiopathic neuropathy is a peripheral nervous system disorder of unknown etiology. Patients with this disorder often suffer from bruxism problems. Bruxism is defined as an oral parafunction characterized by occlusal contacts resulting from non-physiological, repetitive, and involuntary masticatory motor activities. These events can trigger accentuated wear of the tooth structure leading to sensitivity. Tooth sensitivity is the pain arising from the exposed dentin in response to chemical, thermal, tactile, or osmotic stimuli that cannot be explained as the result of any other dental defect or disease. Sensitivity treatment using adhesive systems has a long-term or permanent effect. Therefore, this article is aimed at describing the management of dental sensitivity, through dentin sealing and resin coating techniques, during the dental restoration process of a child with idiopathic neuropathy and dental attrition in the anterior sector. All of this, with the consideration of using the minimal intervention philosophy. CASE PRESENTATION: A 6-year-old male patient diagnosed with idiopathic neuropathy and suffering from multiple dental attritions with dental sensitivity in the upper anterior teeth. With the clinical-radiographic evaluation, the family history, and the interconsultations with the neuropaediatrics service, the definitive diagnosis of dental sensitivity due to stage-3 moderate attrition was obtained, for which rehabilitation of the upper anterior sector was planned through the use of immediate dentin sealing (IDS) and resin coating (RC). CONCLUSION: The use of IDS and RC techniques shows acceptable sensitivity, which is why these techniques are recommended in cases of moderate attrition in early mixed dentition. The immediate rehabilitation along with the stamping technique improved the aesthetic and functional aspects. Therefore, it is advisable to use them immediately after dentin sealing.

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Resumo OBJETIVO: Avaliar a resistência ao cisalhamento e o Índice de Remanescente Adesivo (IRA) de bráquetes metálicos colados com três diferentes fotopolimerizadores LED de alta potência, quando comparados ao LED convencional. MATERIAIS E MÉTODOS: 80 incisivos bovinos foram divididos aleatoriamente em 4 grupos (n=20), nos quais foram realizadas colagens dos bráquetes utilizando-se os seguintes LEDs de alta potência por 3s: Grupo 1 ­ LEDX ­ T 2400, Orthometric; Grupo 2 ­ Flashmax P4 PRO Ortho, Rock Moutain Orthodontics; Grupo 3 ­ VALO CORDLESS, Ultradent e Grupo 4 ­ LED convencional por 40s (controle) POLY-WIRELESS, Kavo. O teste de resistência ao cisalhamento foi realizado utilizando-se uma máquina de ensaio universal (AME-2kN, Oswaldo Filizola, São Paulo, Brasil) com velocidade de 0,5mm/min e célula de carga de 50N. A determinação da diferença estatística entre os grupos em relação ao cisalhamento foi realizada usando-se a análise de variância (ANOVA). Para avaliação do IRA, foi aplicado o teste Kruskal-Wallis. RESULTADOS: O grupo 2 apresentou resistência ao cisalhamento significativamente superior aos demais LEDs de alta potência e foi similar ao LED convencional. Em relação ao IRA, houve diferença estatisticamente significante entre os grupos e o único que não diferiu do grupo controle foi o 2, enquanto os demais LEDs de alta potência (Grupos 1 e 3) apresentaram mais falhas adesivas entre a resina e o esmalte. CONCLUSÃO: Houve diferença entre os três tipos de fotopolimerizadores LED de terceira geração, sendo que maior resistência ao cisalhamento e menos falhas adesivas foram observadas no LED que apresentou maior potência (AU)

Abstract OBJECTIVE: To evaluate shear strength and Adhesive Remnant Index (ARI) of metallic brackets bonded to three types of high-power LED light curing, when compared to conventional LED. MATERIALS AND METHODS: 80 bovine incisors were divided into 4 groups (n = 20), in which brackets were bonded using the following high-power LEDs for 3s: Group 1 ­ LEDX ­ T 2400, Orthometric; Group 2 ­ Flashmax P4 PRO Ortho, Rock Mountain Orthodontics; Group 3 ­ VALO CORDLESS, Ultradent; and Group 4 ­ conventional LED for 40s (control) POLY-WIRELESS, Kavo. The shear strength test was performed using a universal test machine (AME-2kN, Oswaldo Filizola, São Paulo, Brasil) with 0.5 mm/min speed and 50N load cell. The determination of statistical difference between the groups in relation to shear strength was performed using analysis of variance (ANOVA). The Kruskal-Wallis test was used to assess the IRA. RESULTS: Group 2 showed shear strength significantly higher than other high-power LEDs and was similar to conventional LED. Regarding ARI, there was a statistically significant difference between the groups and the only one that did not differ from the control group was 2, while the other high-power LEDs (Groups 1 and 3) had more adhesive failures between the resin and the enamel. CONCLUSION: There was a difference between the three types of third generation LED light curing agents, with greater shear strength and less adhesive failures observed in the LED that presented higher power. (AU)

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Aim: This review investigated the effect of applying an adhesive after surface treatment of glass-ceramics on the bonding, mechanical or clinical behavior. Methods: Studies comparing the adhesive, mechanical or clinical behavior of glass-ceramics, with or without adhesive application after surface treatment, were included. Searches were performed in PubMed, Scopus, and Web of Sciences databases (January 2022), resulting in 15 included studies. Results: Regarding the evaluated outcomes, 13 studies assessed bond strength, 2 studies assessed biaxial flexural strength and 1 study assessed fatigue failure load, while no study evaluating clinical outcomes was included. It was possible to observe that the adhesive application after ceramic surface treatment was unfavorable or did not influence the evaluated outcomes. Conclusion: Most of the evidence available in the literature shows that the adhesive application after surface treatment does not improve the adhesive and mechanical behavior of glass-ceramics

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Abstract Objectives This is a double-blind, split-mouth, randomized clinical study that aims to evaluate the influence of bulk-fill composite packaging presented in syringes (BSy) and capsules (BCa), and the effect of selective enamel etching (SEE) on the clinical performance of class I and II bulk-fill resin composite restorations after 24 months. Methodology A total of 295 class I or class II restorations were performed on 70 patients. One universal adhesive was applied in all restorations. SEE was used in 148 restorations and self-etching mode (SET) in 147 restorations. After the adhesive application, cavities were restored with Filtek Bulk-fill Posterior Restorative in syringes (BSy), Filtek One Bulk-fill in capsules (BCa), or Filtek Supreme Ultra in syringes with the incremental technique (In). All restorations were evaluated using the FDI criteria after one week and after six, 12, and 24 months. Kaplan-Meier survival analysis and Pearson's Chi-square test were used (α=0.05) for statistical analysis. Results After 24 months, 62 patients were evaluated and four restorations were lost due to fracture (one for SEEBSy, two for SEEIn, and one for SETIn). No significant differences in the fracture and retention rate were found between groups (p>0.05). SEE showed significantly fewer marginal adaptation defects than SET (p<0.05). BCa and BSy groups showed fewer marginal discrepancies compared to In (p<0.05). Restorations performed with BCa showed less color mismatch than BSy or In (p<0.05). Conclusion Although all restorations exhibited satisfactory clinical performance after 24 months of clinical service, the clinical behavior of class I and II restorations' improved when performed with a bulk-fill composite in capsules, mainly when associated with a universal adhesive applied with SEE.

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Introducción: se realizó una revisión bibliográfica con el objetivo de conocer, analizar y comparar los diferentes tipos de adhesivos de octava generación que se encuentran en el mercado y la diferencia que existe entre cada uno. Los adhesivos universales han demostrado mejoras en su resistencia, sobre todo en las técnicas de aplicación y en las propiedades de estos materiales, al mejorar la fuerza adhesiva para que el odontólogo pueda brindar tratamientos restaurativos exitosos. Objetivo: conocer, analizar y comparar los diferentes tipos de adhe- sivos de la octava generación empleados en odontología. Material y métodos: se realizó una búsqueda en las bases de datos electrónicas PubMed, BVS, Redalyc y ScienceDirect. Se utilizaron 32 artículos que cumplieron con los criterios predeterminados y la especificidad reque- rida para la pregunta de investigación. Conclusiones: se demostró que la tecnología cada día avanza, sobre todo en el área de los adhesivos, ya que éstos son de mucha utilidad en el día a día del odontólogo; es importante conocer cada uno de éstos, puesto que es un poco complejo seleccionar el correcto, mas no el uso. En la actualidad, existen diversas opciones por las que el odontólogo puede optar, es por ello que el pro- fesional debe estar capacitado sobre cada una de las diferentes marcas existentes y, de acuerdo al tratamiento, debe elegir cuál es mejor utilizar en una rehabilitación. Es importante para el odontólogo conocer estos materiales, ya que esto lo beneficiará al momento de llevar un plan de tratamiento restaurador (AU)

Introduction: a bibliographic review was carried out to learn about, analyze, and compare the different types of eighth-generation adhesives on the market and the difference between each one. Universal adhesives have demonstrated improvements in their resistance, especially in the application techniques and properties of these materials, improving the adhesive strength so that the dentist can provide successful restorative treatments. Objective: to know, analyze and compare the different types of eighth-generation adhesives used in dentistry. Material and methods: a search was made of the following electronic databases: PubMed, BVS, Redalyc, ScienceDirect. Finally, 32 articles that met the predetermined criteria and the specificity required for the research question were used. Conclusions: it was demonstrated that technology is advancing every day, especially in the area of adhesives since these are very useful in the daily life of the dentist. It is important to know each one of these since it is a little complex at the moment of selecting the correct one, but not the use. Currently, there are several options that the dentist can choose, which is why the professional must be trained on each of the various existing brands and according to the treatment which is the best to use at the time of rehabilitation. The dentist needs to know these materials since they will benefit him/her when carrying out a restorative treatment plan (AU)

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To evaluate the effect of ellagic acid on the inhibition of matrix metalloproteinase by analyzing the quality of the adhesive interface with bond strength measures in periods of 24 hours and six months of storage. Method: 40 healthy human third molars were prepared with class I cavities (5x4x3mm). The teeth were divided into four experimental groups: Group 1- without application of ellagic acid and storage time of 24 hours; Group 2- with ellagic acid/24 hours; G3- without ellagic acid/six months; Group 4- with ellagic acid/six months. Then, the cavities were restored with Single Bond Universal adhesive and Z350 composite resin, with and without the previous application of ellagic acid. Subsequently, hourglass-shaped specimens were obtained and subjected to the bond strength (BS) test (n = 10) in a universal testing machine. The bond test was performed after 24 hours and six months of storage. For the standard evaluation (n = 3) the samples were infiltrated with silver nitrate and placed in a developing solution for analysis in a Scanning Electron Microscope (SEM). The data obtained were analyzed with the Kruskal-Wallis non-parametric test, showing a statistically significant difference. Results: The highest bond strength values were found for the 24-hour groups followed by the groups with six months of storage. For nano-infiltration, groups G1 and G2 showed lower infiltration than groups G3 and G4. Conclusion: The previous application of ellagic acid did not affect the BS of the adhesive interface of the adhesive system analyzed, regardless of storage time.

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In this study, an acrylamide-based adhesive was combined with a thiourethane-based composite to improve bond stability and reduce polymerization stress, respectively, of simulated composite restorations. The stability testing was conducted under physiologic conditions, combining mechanical and bacterial challenges. Urethane dimethacrylate was combined with a newly synthesized triacrylamide (TMAAEA) or HEMA (2-hydroxyethyl-methacrylate; control) to produce a 2-step total-etch adhesive system. Methacrylate-based composites (70 wt% silanized filler) were formulated, containing thiourethane oligomers at 0 (control) or 20 wt%. Standardized preparations in human third molars were restored; then, epoxy replicas were obtained from the occlusal surfaces before and after 7-d storage in water or with Streptococcus mutans biofilm, which was tested after storage in an incubator (static) or the bioreactor (mechanical challenge). Images were obtained from the replicas (scanning electron microscopy) and cross sections of the samples (confocal laser scanning microscopy) and then analyzed to obtain measurements of gap, bacterial infiltration, and demineralization. Microtensile bond strength of specimens stored in water or biofilm was assessed in 1-mm2 stick specimens. Data were analyzed with analysis of variance and Tukey's test (α = 0.05). HEMA-based materials had greater initial gap measurements, indicating more efficient bonding for the acrylamide materials. When tested in water, the triacrylamide-based adhesive had smaller gaps in the incubator or bioreactor. In the presence of biofilm, there was less difference among materials, but the acrylamide/thiourethane combination led to statistically lower gap formation in the bioreactor. HEMA and TMAAEA-based adhesives produced statistically similar microtensile bond strengths after being stored in water for 7 d, but after the same period with biofilm-challenged specimens, the TMAAEA-based adhesives were the only ones to retain the initial bond strength values. The use of a stable multiacrylamide-based adhesive led to the preservation of the resin-dentin bonded interface after a physiologically relevant challenge. Future studies will include a multispecies biofilm model.

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Introduction: Endodontically treated teeth are usually affected by extensive structure loss requiring the use of intraradicular posts to provide retention and restoration. Objective: An in vitro assessment was performed on the bonding of glass fiber posts to the root dentin. Material and method: Ninety (n = 10) single bovine roots were used in a 3 x 3 x 3 factorial study with subdivided plots: post customization varying the presence and type of resin (without customization, conventional resin, and Bulk Fill resin), light-curing device (Valo, Radii-Cal, Rainbow), and root third (cervical, middle, and apical). Result: For the customization factor, Tukey's test (5%) showed the superiority of the Bulk Fill (8.16 MPa) and Z350 (7.40 MPa) groups compared to the control group (4.92 MPa), without differing from each other. All light-curing devices differed, showing the superiority of Valo (9.36 MPa), Radii (6.96 MPa) as an intermediate, and the inferiority of Rainbow (4.17 MPa). The cervical root third (7.81 MPa) was superior, the apical third was inferior (5.80 MPa), and the middle third (6.88 MPa) was an intermediate without differing from the others. Conclusion: The customization of glass fiber posts increases the bond strength to the root dentin, regardless of the resin used. There was a compromise in the apical third and when using light-curing devices with lower light intensity.

Introdução: Dentes com extensa perda de estrutura podem comprometer a retenção das restaurações ao remanescente dental, onde pinos intraradiculares são indicados. Objetivo: Avaliou-se in vitro a união de pinos de fibra de vidro à dentina radicular em função de diferentes modos de reanatomização, fotopolimerizadores e regionalização radicular. Material e método: Noventa (n=10) raízes bovinas uniradiculares foram usadas num estudo fatorial 3 x 3 x 3 com parcelas subdivididas: Reanatomização do pino, variando a presença e tipo de resina (Sem reanatomização, Resina Convencional e Resina Bulkfill); Fotopolimerizador (Valo, Radii-cal, Rainbow); e Terço radicular (cervical, médio e apical). Resultado: O teste de Tukey (5%) evidenciou para o Fator Reanatomização superioridade dos grupos BulkFill (8.16MPa) e Z350 (7.40MPa) ao grupo Controle (4.92MPa), sem diferirem entre si. Todos os fotopolimerizadores diferiram entre si, com superioridade de Valo (9.36MPa), Radii (6.96MPa) intermediário, e inferioridade de Raiwbow (4.17MPa). O terço radicular cervical (7.81MPa) foi superior e o apical inferior (5.80MPa), com o terço médio (6.88MPa) intermediário e sem diferir dos demais. Conclusão: Conclui-se que a reanatomização de pinos de fibra de vidro aumenta a resistência de união à dentina radicular, independentemente da resina utilizada, havendo prejuízo no terço apical e quando são empregados fotopolimerizadores com menor intensidade luminosa.

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Aim: This study evaluated the water sorption and solubility of a light-cured resin cement, under four thicknesses and four opacities of a lithium disilicate ceramic, also considering three light-emitting diode (LED) units. Methods: A total of 288 specimens of a resin cement (AllCem Veneer Trans ­ FGM) were prepared, 96 samples were light-cured by each of the three light curing units (Valo ­ Ultradent / Radii-Cal ­ SDI / Bluephase II ­ Ivoclar Vivadent), divided into 16 experimental conditions, according to the opacities of the ceramic: High Opacity (HO), Medium Opacity (MO), Low Translucency (LT), High Translucency (HT), and thicknesses (0.3, 0.8, 1.5, and 2.0 mm) (n = 6). The specimens were weighed at three different times: Mass M1 (after making the specimens), M2 (after 7 days of storage in water), and M3 (after dissection cycle), for calculating water sorption and solubility. Results: The higher thickness of the ceramic (2.0 mm) significantly increased the values of water sorption (44.0± 4.0) and solubility (7.8±0.6), compared to lower thicknesses. Also, the ceramic of higher opacity (HO) generated the highest values of sorption and solubility when compared to the other opacities, regardless of the thickness tested (ANOVA-3 factors / Tukey's test, α = 0.05). There was no influence of light curing units. Conclusion: Higher thicknesses and opacities of the ceramic increased the water sorption and solubility of the tested light-cured resin cement

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The literature has shown that there is no consensus regarding the best resin composite photoactivation protocol. This study evaluated the efficiency of the conventional, soft-start, pulse-delay and exponential protocols for photoactivation of resin composites in reducing the shrinkage stress and temperature variation during the photopolymerisation. The photoactivation processes were performed using a photocuring unit and a smartphone app developed to control the irradiance according each photoactivation protocol. These photoactivation methods were evaluated applying photoactivation energies recommended by the resins manufactures. Three brands of resin composites were analysed: Z-250, Charisma and Ultrafill. The cure effectiveness was evaluated through depth of cure experiments. All results were statistically evaluated using one-way and multi-factor analysis of variance (ANOVA). The use of exponential and pulse-delay methods resulted in a significant reduction of the shrinkage stress for all evaluated resins; however, the pulse-delay method required too long a photoactivation time. The increases on the temperature were lower when the exponential photoactivation was applied; however, the temperature variation for all photoactivation protocols was not enough to cause damage in the restoration area. The evaluation of the depth of cure showed that all photoactivation protocols resulted in cured resins with equivalent hardness, indicating that the choice of an alternative photoactivation protocol did not harm the polymerisation. In this way, the results showed the exponential protocol as the best photoactivation technique for practical applications.

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Data in this article are associated with our research article "Effect of Myricetin on Odontoblast-like Cells and its Potential to Preserve Resin-Dentin Bonds." Both a poor infiltration of resin monomers into the demineralized dentin matrix and hydrolytic degradation of the adhesive could lead to the instability of the resin-dentin interface. The degradation of collagen is caused by matrix metalloproteinases (MMP) and cysteine cathepsins. These collagenolytic enzymes are contained in their latent form as pro-MMPs in the dentinal structure, and undergo activation during the adhesive process. Given that the integrity of the collagen matrix is essential for the preservation of the dentin bond strength in both the medium and long term, the inhibition of these proteases is necessary to improve the durability of adhesive restorations. Among the different strategies suggested to improve both the behavior of the substrate against enzymatic degradation and the biomechanical behavior of the adhesive interface, the use of protease inhibitors and collagen crosslinking agents has been recommended, such as polyphenols. Research has focused on flavonoids such as proanthocyanidins (PAC), a class of phenolic compounds found in a variety of plants such as blueberry and grape whose chemical structure favors their action as cross-linking agents. However, the focus has recently shifted towards myricetin (MYR) due to its chemical structure: a greater amount of hydroxyl groups at the substitution positions, which form bonds with the carbonyl groups of the side chains of collagen amino acids and generate interfiber bonds. Our previous study has shown the efficacy of MYR both as a cross-linking agent and as a MMP inhibitor without any immediate effects on microtensile bond strength (µTBS) and preserving it for six months after storage, and maintaining the odontoblastic phenotype without affecting cell viability. The objective of this article is to present a dataset on the effect of flavonoids PAC and MYR on the resin-dentin interface. Given that durability of the resin-dentin bond holds great importance for the clinical longevity of adhesive restorations, our data aims to show the effects of these flavonoids on resin-dentin µTBS after 18-month storage. Test groups for the µTBS assay were set as follows: G1 (negative control), conventional adhesion technique; G2 (vehicle control), 100% ethanol (EtOH) for 120 s; G3, 0.2% chlorhexidine (CHX) for 60 s; G4, 1% glutaraldehyde (GA) for 60 s; and G5, 600 µM myricetin (MYR) for 120 s. Datasets were exported to SPSS software, version 21.0 (SPSS, Chicago, IL, USA) for analysis using the Shapiro-Wilk, a two-way analysis of variance including factor interactions (treatment and storage time). Data are presented as mean ± standard deviation (SD). Differences with p-values < 0.05 were considered significant. Our data can be used as a basis for comparison among other natural and synthetic substances that could work as MMP inhibitors and crosslinking agents. These findings could be useful for designing an effective strategy towards the stabilization of the hybrid layer in a relevant clinical protocol.

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OBJECTIVE: This study evaluated the effect of beam homogeneity on the microtensile bond strength (µTBS) of two adhesive resins to dentin. METHODS: One polywave light-emitting-diode (LED) LCU (Bluephase Style, Ivoclar Vivadent AG) was used with two different light guides: a regular tip (RT, 1010 mW/cm2 emittance) and a homogenizer tip (HT, 946 mW/cm2 emittance). The emission spectra and beam profiles were measured from both light guides. Extracted third molars were prepared for µTBS evaluation using two adhesive systems: Excite F (EXF) and Adhese Universal (ADU). Bond strength was calculated for each specimen (n = 10) at locations that correlated with the output of the two LED chips emitting blue (455 nm) and the one chip that emitted violet light (409 nm) after 24-hs and after one-year water-storage. The µTBS was analyzed using a four-way analysis of variance (factors: adhesive system, light guide, LED wavelength, and storage time) and post-hoc Tukey test (α = 0.05). RESULTS: EXF always delivered a higher µTBS than ADU (p < 0.0001), with the µTBS of ADU being about 20% lower than EXF. The light guide (p = 0.0259) and storage time (p = 0.0009) significantly influenced the µTBS. The LED wavelengths had no influence on the µTBS (p > 0.05). SIGNIFICANCE: Homogeneity of the emitted light beam was associated with higher 24-h µTBS to dentin, regardless of the adhesive tested. Also, differences in the composition of adhesives can affect their compatibility with restorative composites and their ability to maintain bonding over one year.

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OBJECTIVE: Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin-based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin-based restorative materials with nanoparticles. MATERIALS AND METHODS: A literature review was conducted using PubMed/Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin-based restorative materials containing nanoparticles were included. RESULTS: A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti-bacterial properties were described. The clinical performance of resin-based restorative materials with nanoparticles was also reported. CONCLUSIONS: The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future. CLINICAL SIGNIFICANCE: In spite of the recent advancements of nanotechnology in resin-based restorative materials, some challenges need to be overcome before new nano-based restorative materials are considered permanent solutions to clinical problems.

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Objective: The objective of this study was to characterize and correlate the absorption spectra of three photoinitiators [camphorquinone (CQ), diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO)], using second or third-generation light curing units (LCU), and to evaluate the degree of conversion and the physical properties of an experimental resin adhesive. Material and methods: Second-generation (Radii-cal® and Emitter D®) and third-generation (Valo® Cordless and Bluephase N®) LCU were assessed regarding spectrum and irradiance rate of emitted light. Also, the photoinitiators (CQ, TPO and BAPO) were characterized by a light absorption spectrum assessed by UV-Vis spectroscopy, degree of conversion and yellowing effect. Statistical analyzes considered two-way ANOVA and post-hoc Tukey test. Results: BAPO presented higher reactivity compared to TPO. Regarding degree of conversion of the photoinitiators activated by different light-curing units, the Emitter D® device promoted a high degree of conversion. BAPO presented the highest yellowing effect values. Conclusions: The emission and absorption characteristics of the photoinitiators were different. The polymerization reaction activated by the second-generation light-curing unit was reduced when using an experimental resin with photoinitiator TPO, and the third-generation light-curing unit showed a higher polymerization potential regardless of the photoinitiator. (AU)

Objetivo: Caracterizar e correlacionar os espectros de absorção de três fotoiniciadores [canforoquinona (CQ), difenil 2,4,6-trimetilbenzil óxido de fosfina (TPO) e óxido de di (2,4,6-trimetilbenzil) difenil fosfina (BAPO)], com unidades de fotoativação (LCU) de segunda ou terceira geração, e avaliar o grau de conversão e as propriedades físicas de um adesivo experimental. Material e métodos: LCU de segunda geração (Radii-cal® e Emitter D®) e terceira geração (Valo® Cordless e Bluephase N®) foram avaliadas quanto ao espectro e taxa de irradiância da luz emitida. Além disso, os fotoiniciadores (CQ, TPO e BAPO) foram caracterizados por um espectro de absorção de luz avaliado por espectroscopia UV-Vis, avaliado o grau de conversão dos adesivos e efeito de amarelamento. A análise estatística empregada foi ANOVA duas vias e teste post-hoc de Tukey. Resultados: BAPO apresentou maior reatividade comparado ao TPO. Em relação ao grau de conversão dos fotoiniciadores ativados por diferentes aparelhos fotopolimerizadores, o dispositivo Emitter D® promoveu um alto grau de conversão. BAPO apresentou os maiores valores de efeito de amarelamento. Conclusões: As características de emissão e absorção dos fotoiniciadores foram diferentes. A reação de polimerização ativada pelas unidades de fotopolimerização de segunda geração foi reduzida com o uso de uma resina experimental com fotoiniciador TPO. As unidades de fotopolimerização de terceira geração apresentaram maior potencial de polimerização independentemente do fotoiniciador. (AU)

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Abstract Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes. Methodology: A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes. Results: The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05). Conclusion: Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.

Assuntos

RESUMO

Contraction due to polymerization of dental resin can cause failure on the adhesive interfaces, can lead to problems such as the appearance of gaps in the interfaces, postoperative sensitivity, pulp damage and the return of the caries. The objective of this work is the study of stresses on the dental adhesive that are generated by the process shrinkage of resin associated with biting forces. A laboratory experiment measured the strains and temperature inside the FiltekTM Bulk Fill Flow resin during the process of polymerization using Fiber Bragg Grating sensors in an ex vivo tooth. From tomographic images a three-dimensional geometric model of the tooth was reconstructed. A pre-tension was calibrated to simulate the residual contraction on the resin 3 D model. Finally, an Finite Element Method analysis was performed to access the adhesive stresses at the interface enamel/dentin with the adhesive, considering as loading the residual polymerization contraction of the dental resin and also biting loads. The model was able to represented the strain obtained in the laboratory experiment. The results of the stress analysis shows that the outer regions of adhesive are more prone to failure, as veried by dental surgeons in clinical practice.

Assuntos

RESUMO

The aim of the present study was to formulate dental adhesives with different concentrations of LiNbO3 and to evaluate their physicochemical and antibacterial properties. A dental adhesive was formulated using methacrylate monomers and photoinitiators and used as a control filler-free group. Subsequently, three experimental adhesives doped with LiNbO3 at different concentrations (1 wt.%, 2 wt.%, and 5 wt.%) were also formulated. All the experimental adhesives were assessed to evaluate the degree of conversion (DC), softening in solvent, immediate and long-term microtensile bond-strength (µ-TBS), radiopacity, ultimate tensile strength, and antibacterial activity. The incorporation of 1 wt.% of LiNbO3 had no negative effect on the DC of the adhesive resin compared to the control group (p > 0.05). We observed a decrease in the percentage of softening in solvent in the group LiNbO3 at 1 wt.% (p < 0.05). The addition of LiNbO3 increased the radiopacity at a concentration above 2 wt.%, and there was also an increase in cohesive strength (p < 0.05). The immediate µ-TBS increased for LiNbO3 at 5 wt.% (p < 0.05), and there was no statistical difference for the other groups compared to the control (p > 0.05). After six months, the group with 5 wt.% still presented the highest µ-TBS (p < 0.05). The adhesives showed no antimicrobial activity (p > 0.05). LiNbO3 was successfully incorporated in dental adhesives, increasing the radiopacity and their resistance to degradation. Although LiNbO3 offered no antibacterial properties, the reliability of LiNbO3 incorporation in the adhesive encourages new tests to better investigate the antimicrobial action of LiNbO3 through temperature variation.

RESUMO

The insufficient radiopacity of dental adhesives applied under composite restorations makes the radiographic diagnosis of recurrent caries challenging. Consequently, the misdiagnosis may lead to unnecessary replacement of restorations. The aims of this study were to formulate experimental dental adhesives containing cerium dioxide (CeO2) and investigate the effects of different loadings of CeO2 on their radiopacity and degree of conversion for the first time. CeO2 was characterized by X-ray diffraction analysis, Fourier transforms infrared spectroscopy, and laser diffraction for particle size analysis. Experimental dental adhesives were formulated with CeO2 as the inorganic filler with loadings ranging from 0.36 to 5.76 vol.%. The unfilled adhesive was used as a control. The studied adhesives were evaluated for dispersion of CeO2 in the polymerized samples, degree of conversion, and radiopacity. CeO2 presented a monoclinic crystalline phase, peaks related to Ce-O bonding, and an average particle size of around 16 µm. CeO2 was dispersed in the adhesive, and the addition of these particles increased the adhesives' radiopacity (p < 0.05). There was a significant decrease in the degree of conversion with CeO2 loadings higher than 1.44 vol.%. However, all materials showed a similar degree of conversion in comparison to commercially available adhesives. CeO2 particles were investigated for the first time as a promising compound to improve the radiopacity of the dental adhesives.