Desensitizing Agent Previously Applied During In-Office Bleaching: A Double-Blind Randomized Clinical Trial

Abstract Objective: To compare the clinical effect of two desensitizing agents used before the application of a bleaching gel based on 35% hydrogen peroxide (HP). Material and Methods: 30 patients were selected, and two desensitizing agents with different mechanisms of action were applied: Fluorine Neutral 2% (FN), which acts by blocking dentinal canaliculi while Potassium Nitrate 5% with 2% Sodium Fluoride (PN/SF) that acts in nerve transmission and blockade. Desensitizers were used before the application of 35% HP. For whitening, three clinical sessions were performed, with an interval of seven days, with three applications of the bleaching gel for 15 minutes, totaling 45 minutes/session. Tooth sensitivity (TS) was assessed with the numerical analog scale, and a spectrophotometer was used to obtain the color variation (ΔE). ΔE were submitted to ANOVA and Tukey test (p<0.05), and TS data were submitted to a two-way ANOVA analysis. Results: For sensitivity experience, the Tukey test indicated differences between PN/SF and the placebo I, but there was no statistically significant difference between FN and the placebo II. The TS was lower when the desensitizing gel was used during the bleaching procedure compared to after treatment, regardless of the desensitizing agents. Conclusion: PN/SF before in-office tooth bleaching can reduce TS intensity, and the use of desensitizing gel before bleaching did not affect the bleaching efficacy.

Substituição de restauração classe IV em resina composta: relato de caso clínico / Class IV restoration replacement in composite resin: clinical case report

Introdução: a estética é um fator decisivo para a substituição de restaurações anteriores que apresentam falhas, causadas principalmente por alterações na coloração ou fraturas. Objetivo: o presente relato de caso descreve a substituição de uma restauração classe IV insatisfatória, apresentando o protocolo clínico utilizado desde o planejamento até a reabilitação definitiva, com o propósito de difundir o conhecimento sobre a técnica adotada e auxiliar outros profissionais no seu cotidiano clínico. Relato do caso: paciente JPJ, 28 anos, sexo masculino, apresentou-se ao consultório odontológico queixando-se do aspecto estético de uma restauração em resina composta no seu dente anterior. Durante o exame físico intrabucal foi identificada a presença de uma restauração classe IV insatisfatória no elemento 21, apresentando degradação e manchamento superficial. Para uma análise estética completa e planejamento do caso, foram realizadas fotografias intrabucais e moldagem com alginato para confecção de modelos de gesso. Resultados: como tratamento, foi realizado profilaxia, isolamento absoluto e substituição da restauração do dente 21 pela técnica direta com o auxílio de uma guia de silicone. Foi utilizado um sistema adesivo convencional de 2 passos (Single Bond 2, 3M ESPE, St. Paul, MN, USA) e resinas compostas nanohíbridas (Empress Direct, Ivoclar-Vivadent, Barueri, SP, BRA), uma para reprodução do esmalte e outra para dentina. Por fim, foram realizados acabamento e polimento das restaurações. Conclusão: restaurações diretas com resinas compostas, quando bem indicadas e executadas, permitem a devolução da função de forma satisfatória e resultados altamente estéticos.

Introduction: aesthetics are a decisive factor in replacing anterior restorations that present failures, mainly caused by color changes or fractures. Objective: this case report describes the replacement of a class IV restoration with composite resin by the direct technique, presenting the clinical protocol used, from planning to definitive rehabilitation, with the purpose of spreading knowledge of the technique and helping other professionals in their daily clinical routine. Case report: patient JPJ, 28 years old, male, presented to the dental office complaining about the aesthetic aspect of a composite resin restoration on his anterior tooth. During the intraoral physical examination, the presence of a class IV restoration in element 21 was identified, which was unsatisfactory due to degradation and surface staining. For a complete and detailed esthetic analysis, intraoral photographs and molding with alginate were taken to make plaster models. Results: as a treatment, prophylaxis, absolute isolation and replacement of the restoration of tooth 21 were performed by the direct technique with the aid of a silicone guide. A conventional 2-step adhesive system (Single Bond 2, 3M ESPE, St. Paul, MN, USA) and nanohybrid composite resins (Empress Direct, Ivoclar-Vivadent, Barueri, SP, BRA) were used, one for enamel reproduction and another for dentine. Finally, finishing and polishing of the restorations were carried out. Conclusion: direct restorations with composite resins, when properly indicated and executed, allow the return of function in a satisfactory way and highly esthetic results.

Surface roughness evaluation and whitening efficiency on tooth enamel after using whitening toothpaste: a randomized double-blinded study

The aim of this randomized double-blinded study was to evaluate the enamel surface roughness and color change after one month of whitening toothpaste use and the color stability obtained 1 month after its interruption. 30 volunteers were divided into 3 groups (n = 10) corresponding to the dentifrices: 1) Colgate Total 12 Clean Mint (TD) (Control), 2) Colgate Luminous White (LW) and 3) Sensodyne Whitening Extra Fresh (SB). The volunteers were impression with addition silicone to obtain an epoxy resin replica of the upper central incisor for the initial surface roughness evaluation using a profilometer and the initial color of the incisors and canines was evaluated with a spectrophotometer after one week of wash-out. After 1 month, the color of the central incisors and canines was measured again, and the volunteers were molded to obtain a second replica to the final roughness analysis. Data were submitted to ANOVA-one way (p≤0.05). The results showed that there was no statistical difference between the dentifrices for color difference and surface roughness for all the studied conditions. It was possible to conclude that the whitening dentifrices used in this study were not able to alter the initial color of the teeth and did not cause changes in the surface roughness of enamel.

Ellagic acid on the quality of the adhesive interface of class I composite resin restorations after aging

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.

Effects of desensitizing products on the reduction of pain sensitivity caused by in-office tooth bleaching: a 24-week follow-up.

OBJECTIVE: To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching. METHODOLOGY: A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05). RESULTS: The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning. CONCLUSION: Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

Effects of desensitizing products on the reduction of pain sensitivity caused by in-office tooth bleaching: a 24-week follow-up

Abstract Objective To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching. Methodology A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05). Results The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning. Conclusion Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

Effects of desensitizing dentifrices on the reduction of pain sensitivity caused by in-office dental whitening: a double-blind controlled clinical study.

Objective: The purpose of this study was to clinically evaluate the influence of desensitizing dentifrices applied through a plastic tray on reducing the pain sensitivity and color variation caused by in-office dental whitening and to evaluate differences among such dentifrices through a controlled double-blind clinical study. Materials and methods: A prospective study was conducted with 48 individuals between 18 and 30 years without gender distinction. For the dental whitening, 35% hydrogen peroxide was used in three clinical sessions. After each whitening session, the volunteers used a plastic tray containing one of the dentifrices (sucralose- S, sodium fluoride - SF, arginine and calcium carbonate - ACC, and 5% potassium nitrate - PN) for 4 hrs during the night. The evaluation of the sensitivity associated with the use of the plastic tray in each whitening session was performed using the analog numerical scale with scores from 0 to 10. The color variation (ΔE) was determined with a spectrophotometer. The pain sensitivity data were submitted to the multivariate analysis of variance with repeated measurements and a Lambda Wilks test (p<0.05). To analyze the color variation, a one-way ANOVA was applied (p<0.05). Results: The ACC and 5% NP groups showed a reduction in sensitivity in relation to the other groups (p<0.05). There was a reduction in sensitivity after placement of the tray with dentifrice. The color evaluation associated with the dentifrice showed no difference (p=0.9186). Conclusion: The use of desensitizing dentifrices with ACC or 5% NP in a plastic tray was effective for the reduction of pain sensitivity, and the use of a desensitizing dentifrice did not decrease the effectiveness of whitening.

Evaluation of Finishing/Polishing Techniques on Low-Shrink Posterior Restorative After Mechanical Cycling / Avaliação de Técnicas de Acabamento/Polimento em Restaurações Posteriores de Baixa Contração Após Ciclagem Mecânica

The aim of this study was to evaluate the surface roughness of a silorane and methacrylate-based composite resins subjected to different finishing/polishing techniques. Twelve disk specimens were prepared from each composite resin: P90®, Z350® and Charisma, divided into 12 groups according to the finishing/polishing technique: no finishing/polishing (control); finishing with 1112 FF diamond burs; finishing with 1112 FF diamond burs associated to Enhance/Pogo; finishing with 1112 FF diamond burs associated to Enhance/Pogo/Polishing/Poli I and II pastes/Fotogloss. After initial readouts of surface roughness, the specimens were subjected to mechanical cycling (1.200.000 cycles) and immediately subjected to final roughness readouts. Surface roughness means was statistically analyzed by ANOVA and Tukey-Kramer test (α=0.05). SEM images were realized after finishing/polishing and after mechanical cycling. The P90 composite showed surface roughness values similar to other investigated composites. However, significant difference was observed in finishing/polishing techniques. The diamond burs group showed the highest surface roughness differing from the other composite resins (α < 0.05). Enance/Pogo showed the lowest results, which presented no difference compared to the polishing paste group (α > 0.05). The low-shrink posterior restorative showed similar surface roughness when compared to dimethacrylate composite resins and suitable to posterior restorations. (AU).

O objetivo deste estudo foi avaliar a rugosidade superficial de resinas compostas à base silorano e metacrilato submetidas a diferentes técnicas de acabamento/polimento. Foram preparadas 12 amostras de disco de cada resina composta: P90®, Z350® e Carisma, divididas em 12 grupos de acordo com a técnica de acabamento / polimento: sem acabamento / polimento (controle); acabamento com ponta diamantada 1112 FF; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo / Polishing / Pastas Poli I e II / Fotogloss. Após as leituras iniciais da rugosidade da superfície, os espécimes foram submetidos a ciclos mecânicos (1.200.000 ciclos) e submetidos imediatamente a leituras de rugosidade final. As medias de rugosidade superfícial foram analisadas estatisticamente por ANOVA e teste de Tukey-Kramer (α = 0,05). As imagens de MEV foram realizadas após o acabamento / polimento e após a ciclagem mecânica. O compósito P90 mostrou valores de rugosidade superficial semelhantes a outros compósitos investigados. Tough, mostrou diferença significativa nas técnicas de acabamento / polimento. O grupo de pontas damantadas apresentou maior rugosidade superficial que diferiu das outras resinas compostas (α <0,05). Enance / Pogo mostrou os menores resultados, que não apresentaram diferença em relação ao grupo de pasta de polimento (α> 0,05). O material restaurador posterior de baixa contração apresentou rugosidade superficial semelhante quando comparado as resinas compostas de dimetacrilato e são restaurações adequadas para região posterior. (AU).

Evaluation of degree of conversion and the effect of thermal aging on the color stability of resin cements and flowable composite.

PURPOSE: The aim of this in vitro study was to evaluate the color stability and degree of conversion (DC) of dual-cure and light-cure cements and flowable composites after thermal aging. MATERIALS AND METHODS: A total of 50 human incisors were prepared and divided into six groups (n = 10). Veneers were fabricated using IPS Empress Direct composite resin were bonded with three types of luting agents: Light-cured, conventional dual, and flowable composite according to the manufacturer's instructions. The groups were as follows: Filtek Z350XT Flow/Single Bond 2, RelyX ARC/Single Bond 2, RelyX Veneer/Single Bond 2, Tetric N-Flow/Tetric N-Bond, and Variolink II/Tetric N-Bond. Commission Internationale de l'Éclairage L*, a* and b* color coordinates were measured 24 h after cementation procedure with a color spectrophotometer and reevaluated after 10,000 thermal cycles. To evaluate the DC 50 specimens (n = 10) of each resin material were obtained and Fourier transform infrared spectroscopy was used to evaluate the absorption spectra. Statistical analysis was performed with one-way ANOVA and Tukey's test (α = 0.05). RESULTS: No statistically significant differences in ΔE* occurred after aging. The greatest change in lightness occurred in the Variolink II resin cement. Changes in red-green hue were very small for the same cement and largest in the Tetric N-Flow flowable resin composite, while the greatest change in blue-yellow hue was a yellowing of the RelyX ARC luting cement. RelyX ARC exhibited the highest DC, and there were no statistically significant differences in DC among the other cements. CONCLUSIONS: Resin-based luting agent might affect the final of ceramic veneer restorations. The thermal aging affected the final color of the evaluated materials, and these were regarded as clinically unacceptable (ΔE >3.3).

Influence of whitening dentifrices and mechanical brushing on color change and surface roughness of bulk fill resins

The use of whitening dentifrices during oral hygiene may cause surface modifications such as color change (ΔE) and increase surface roughness (Ra) of composite resin. Aim: This study aimed to evaluate the effect of whitening dentifrices and mechanical brushing on color change and surface roughness of Bulk Fill (Filtek Bulk Fill - F) and (Aura Bulk Fill - A) composite resins. Materials and methods: Sixty cylindrical specimens were fabricated of each composite resin. After initial color evaluations (Konica Minolta CM-700d), with D65 standard illuminant, and the surface roughness (Surfcorder SE 1700, Kosalab), the specimens were assigned (n=10) according to the whitening dentifrice used: True White (T), Colgate Total 12 Professional Whitening (D), Luminous White Advanced (L). Specimens were submitted to mechanical brushing (10,000 cycles); new color and surface roughness evaluations were taken. Data were analyzed by ANOVA, Duncan test and Dunnet test were used to identify differences between groups (α=5%). Results: The results showed that the tooth brushing time promoted a significant increase in ΔE of the FT group. The FD group exhibited intermediate values of ΔE and was similar to all groups tested. There was a significant increase in the surface roughness of the AD and AT groups after the mechanical tooth brushing. Conclusion: The results showed no significant changes were observed in surface roughness for F groups after toothbrushing. It be concluded that the color change and surface roughness of the composite resins after toothbrushing are dependent on the interaction between the composition of the composite resin and the characteristics of the dentifrice

Influence of enamel acid-etching on mechanical properties and nanoleakage of resin composite after aging

The aim of this study was to evaluate how acid-etching of the cavosurface enamel in Class I resin composite restorations influences the bond strength to the pulpal wall and the restoration, Knoop microhardness and nanoleakage after thermomechanical aging. For this research 76 fresh human molars were selected and restored with Silorane or Clearfil SEBond/Z350XT composite divided in 4 groups (Silorane system restored with or without enamel cavosurface acid-etching and Clearfil SEBond/Z350XT with or without enamel cavosurface acid-etching). To induce artificial aging, samples were subjected to thermomechanical cycling through 200,000 and thermal cycling between 5 and 55 °C with 30 second filling and 15-second drainage steps. Microhardness and microtensile bond strength were evaluated in 32 teeth (n=8) each and nanoleakage evaluation was performed in 12 teeth (n=3). Samples restored by Clearfil SEBond/Z350 XT without cavosurface acid-etching showed significantly lower microtensile bond strength results. The resin composite Z350XT presented higher values of Knoop microhardness. It was observed little or no infiltration for Silorane groups and moderate infiltration for Clearfil SE Bond groups. Acid-etching of the cavosurface enamel during restoration procedure with Clearfil Se Bond resulted in a stronger bond after thermomechanical cycling. Silorane groups showed less infiltration than Clearfil SE Bond groups (AU)

Active application of primer acid on acid-treated enamel: Influence on the bond effectiveness of self-etch adhesives systems.

AIM: Evaluate the composite-to-enamel bond after passive or active application of self-etching primer systems on polished or pre-etched enamel with phosphoric acid. MATERIALS AND METHODS: Two self-etch adhesives systems (SEAS) were used: Clearfil SE Bond and Easy Bond. Third human molars were divided into 8 groups (N = 10). The crown of each tooth was sectioned into halves and the mesial/distal surfaces were used. The adhesives were actively or passively applied on enamel with or without prior phosphoric-acid etching. Resin composite cylinders were built after adhesive application. After stored in relative humidity for 24 hr/37°C the specimens were subjected to microshear test in universal testing a machine at a crosshead speed of 0.5 mm/minute. The results were analyzed with three-way ANOVA and the Tukey test. The enamel-etching pattern was evaluated under SEM. RESULTS: The 2-step SEAS system presented significantly higher adhesive bond strength means (47.37 MPa) than the 1-step (36.87 MPa). A poor enamel- etching pattern was observed in active mode showing irregular and short resin tags, however there was not compromised the bond strength. CONCLUSION: Active or passive application produced similar values of bond strength to enamel regardless of enamel pretreatment and type of SEAS.

Color stability and polymerization behavior of direct esthetic restorations.

OBJECTIVES: The current study evaluated the effect of accelerated artificial aging (AAA) on the color stability (CS) and degree of conversion (DC) of nanofilled and nanohybrid resin composites associated to different adhesive systems in direct esthetic restorations. MATERIAL AND METHODS: Eighty bovine incisors were used to obtained dentin blocks (4 × 4 × 1 mm). The restorative systems were bonded to the blocks and photoactivated according to the manufacturer's instructions. Three adhesive systems were used: Adper Scotchbond Multi-Purpose (conventional of three steps), Tetric N-Bond (conventional of two steps) and ClearFill SE Bond (self-etching). Also, two composites were used: Filtek Z350 XT (nanofilled) and IPS Empress Direct (nanohybrid). The restorations were made using a silicone mold placed on top of the prepared dentin blocks (N = 10). CS was measured after 300 hours of AAA by means of ultraviolet light using a spectrophotometer and CIE L*a*b* parameters on the top surface of the composite and at the bonded interface. The DC was performed using Fourier transform infrared spectroscopy (N = 10). Data were analyzed using two-way analysis of variance and Tukey's test (α = 0.05). RESULTS: The adhesive systems had no significant influence on the color stability (ΔE) of either the restoration surface (α = 0.90) or the bonded interface (α = 0.78). However, composite influenced the color as measured by ΔE and isolated coordinates (α < 0.001). The nanohybrid composite showed increased DC values (67%) compared with the nanofilled (61%) with statistically significant differences (α < 0.001). CONCLUSIONS: The adhesive system did not affect the final color of direct esthetic restorations. The nanohybrid composite demonstrated a higher DC and increased color stability after AAA compared to the nanofilled composite. CLINICAL SIGNIFICANCE: The long-term color stability of composite restorations is a critical aspect of esthetic restorative procedures. Optimal Polymerization behavior of resin composite as indicated by the degree of conversion also influence on the color stability after artificial aging of composite restorations.

Influence of photo-curing distance on bond strength and nanoleakage of self-etching adhesive bonds to enamel and dentin.

OBJECTIVES: To assess the influence of light-curing unit tip distance on the microtensile bond strength (µTBS) and nanoleakage of self-etching adhesives to enamel and dentin. MATERIALS AND METHODS: Flat buccal surfaces were prepared on 198 bovine incisors. The teeth were randomly assigned into nine groups for µTBS (n = 8) and nanoleakage (n = 3) testing according to the adhesive system (Clearfil Protect Bond, Clearfil Tri-S Bond or One Up Bond F Plus) and distance from the light-curing tip (0, 3 or 6 mm). The bonded samples were tested in tension (0.5 mm/min) and nanoleakage was analyzed using SEM. RESULTS: Clearfil Protect Bond exhibited the highest tensile strength on both enamel and dentin. Leakage was higher in samples exposed at a distance of 6 mm on enamel and 0 mm on dentin. One Up Bond F Plus experienced the greatest amount of nanoleakage on both substrates. CONCLUSIONS: Light-curing unit distance did not influence the µTBS of the adhesives, but nanoleakage increased on enamel samples when photoactivation occurred at a distance of 6 mm.

Resolução estética: fechamento de diastemas e contorno cosmético / Aesthetic resolution: diastema closure and cosmetic makeover

Alterações de forma e posição podem levar a formação de diastemas e afetar a estética do sorriso. Atualmente, em função da expectativa do tempo de tratamento, pequenas alterações de posicionamento facilmente corrigidas imediatamente pela técnica restauradora sem auxílio ortodôntico é uma opção favorável de tratamento nestes casos. O objetivo desse trabalho é apresentar, em um caso clínico, um método de utilização de resinas na recuperação estética através do contorno cosmético para correção do sorriso sem a intervenção da técnica ortodôntica

Knoop hardness and effectiveness of dual-cured luting systems and flowable resin to bond leucite-reinforced ceramic to enamel.

PURPOSE: The aim of this study was to evaluate the Knoop microhardness and microshear bond strength (MSBS) of dual-cured luting systems and flowable resin bonded to leucite-reinforced ceramics and enamel. MATERIALS AND METHODS: Eighty bovine incisors were randomly divided into four groups per test (microhardness and microshear; n = 10) according to the bonding procedure: Excite DSC/Variolink, Clearfil SE Bond/Panavia F, Adper Scotchbond Multi-Purpose Plus/RelyX ARC, and Adper Single Bond 2/Filtek Z350 Flow. For the KHN measurement, the cement was applied on the enamel surface and light-cured through a ceramic disk (5 mm diameter × 1.2 mm thick). Five indentations were performed in each specimen and measured at HMV-2. For the microshear test, two cylinders of a leucite-reinforced ceramic (1 mm diameter × 2 mm height) were bonded to the enamel substrate in accordance with the bonding procedures previously established. One cylinder was tested 24 hours after cementation, and the other was subjected to thermocycling (2000 cycles) and then submitted to an MSBS test. The data from the hardness and bond strength tests were subjected to one- and two-way repeated-measures analysis of variance (ANOVA), respectively, and to Tukey's test (α= 0.05). RESULTS: Scotchbond/RelyX ARC presented higher values of bond strength, while Single Bond/Z350 Flow showed lower values. The thermocycling promoted a reduction in the bond strength values for all groups. Panavia F presented higher values of KHN, and the flowable resin presented the lowest. RelyX ARC and Variolink presented intermediate values on hardness evaluation. CONCLUSIONS: For ceramic cementation, dual-cured resin luting systems promoted more reliable bonding and microhardness values than the flowable resin.

Reforço intrarradicular de raízes debilitadas / Intra-root strengtening of weakened roots

A instrumentação dos canais radiculares através do uso de lima única em movimento recíproco vem se popularizando devido à redução do tempo de trabalho e menor tendência de fraturas dos instrumentos. Antes de escolher o sistema que vai utilizar, o cirurgião- -dentista deve conhecer as capacidades e limitações de cada sistema baseado em evidências científicas. Esse artigo realizou uma revisão de literatura sobre o movimento recíproco para instrumentação do sistema de canais radiculares apontando as vantagens e desvantagens da utilização dessa cinemática de instrumentação.

The canal’s instrumentation by using single file in reciprocation movement is gaining popularity due to the reduction of working time and less prone to fractures of the instruments. Before choosing which system will use, the dentist must know the capabilities and limitations of each system based on scientific evidence. This article reviews the literature on the reciprocation movement pointing out the advantages and disadvantages of this different kinematic instrumentation.

Nanoleakage evaluation of resin luting systems to dental enamel and leucite-reinforced ceramic.

PURPOSE: The aim of this study was to evaluate the nanoleakage patterns between dental enamel and reinforced leucite ceramic, bonded with resin luting systems and a flowable composite resin. MATERIALS AND METHODS: Twelve crowns of bovine incisors were randomly divided into four groups (n = 3) according to the luting procedure: Excite/Variolink II, Clearfil SE Bond/Panavia F, Scotchbond Multi-PURPOSE Plus/RelyX ARC, and Single Bond 2/Filtek Z350 Flow. To evaluate the nanoleakage patterns, IPS Empress Esthetic disks (5 mm Ø and 1.2-mm thick) were bonded to enamel, and, after 24 h, the specimens were immersed in a 50% (w/v) solution of silver nitrate (24 h), fixed, dehydrated, and processed scanning electron microscopy (SEM). RESULTS: None nanoleakage on interface of the groups that Single Bond 2 followed by the flowable composite were used. The highest percentage of nanoleakage was shown by the Excite/Variolink II protocol. Also, in all conditions tested, none silver nitrate uptake was observed between the leucite-reinforced ceramic and the resin luting cement. CONCLUSIONS: The use of a two-step etch-and-rinse adhesive with flowable composite was able to promote an adequate seal of the bond interface at the enamel. Moreover, the conventional dual-cured resin cements associated with simplified and dual-cured adhesives tested are also indicated to bond thin ceramics to enamel, since all presented low silver nitrate uptake.

The effect of curing light and chemical catalyst on the degree of conversion of two dual cured resin luting cements.

The aim of this study was to evaluate the influence of different curing lights and chemical catalysts on the degree of conversion of resin luting cements. A total of 60 disk-shaped specimens of RelyX ARC or Panavia F of diameter 5 mm and thickness 0.5 mm were prepared and the respective chemical catalyst (Scotchbond Multi-Purpose Plus or ED Primer) was added. The specimens were light-cured using different curing units (an argon ion laser, an LED or a quartz-tungsten-halogen light) through shade A2 composite disks of diameter 10 mm and thickness 2 mm. After 24 h of dry storage at 37°C, the degree of conversion of the resin luting cements was measured by Fourier-transformed infrared spectroscopy. For statistical analysis, ANOVA and the Tukey test were used, with p ≤ 0.05. Panavia F when used without catalyst and cured using the LED or the argon ion laser showed degree of conversion values significantly lower than RelyX ARC, with and without catalyst, and cured with any of the light sources. Therefore, the degree of conversion of Panavia F with ED Primer cured with the quartz-tungsten-halogen light was significantly different from that of RelyX ARC regardless of the use of the chemical catalyst and light curing source. In conclusion, RelyX ARC can be cured satisfactorily with the argon ion laser, LED or quartz-tungsten-halogen light with or without a chemical catalyst. To obtain a satisfactory degree of conversion, Panavia F luting cement should be used with ED Primer and cured with halogen light.

Influence of the LED curing source and selective enamel etching on dentin bond strength of self-etch adhesives in class I composite restorations.

The aim of this study was to evaluate the influence of the LED curing unit and selective enamel etching on dentin microtensile bond strength (µTBS) for self-etch adhesives in class I composite restorations. On 96 human molars, box-shaped class I cavities were made maintaining enamel margins. Self-etch adhesives (Clearfil SE - CSE and Clearfil S(3) - S3) were used to bond a microhybrid composite. Before adhesive application, half of the teeth were enamel acid-etched and the other half was not. Adhesives and composites were cured with the following light curing units (LCUs): one polywave (UltraLume 5 - UL) and two single-peak (FlashLite 1401 - FL and Radii Cal - RD) LEDs. The specimens were then submitted to thermomechanical aging and longitudinally sectioned to obtain bonded sticks (0.9 mm(2)) to be tested in tension at 0.5 mm/min. The failure mode was then recorded. The µTBS data were submitted to a three-way ANOVA and Tukey's (α = 0.05). For S3, the selective enamel-etching provided lower µTBS values (20.7 ± 2.7) compared to the non-etched specimens (26.7 ± 2.2). UL yielded higher µTBS values (24.1 ± 3.2) in comparison to the photoactivation approach with FL (18.8 ±3.9) and RD (19.9 ±1.8) for CSE. The two-step CSE was not influenced by the enamel etching (p ≥ 0.05). Enamel acid etching in class I composite restorations affects the dentin µTBS of the one-step self-etch adhesive Clearfil S(3), with no alterations for Clearfil SE bond strength. The polywave LED promoted better bond strength for the two-step adhesive compared to the single-peak ones.