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

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

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

Analysis of self-etch adhesives behavior in class I composite restorations with different treatment of enamel margins and light-activation sources/ Análise do comportamento de adesivos autocondicionantes em restaurações de resina composta classe I com diferentes tratamentos das margens de esmalte e fontes de ativação de luz

Objective: To evaluate the microtensile bond strength (MTBS), knoop microhardness (KHN) and gap formation of class I restorations restored with self-etching adhesives and resin composites light-activated by either halogen or LED light curing units. Materials and Methods: Class I cavities were prepared in one hundred and forty-four human third molars. Three self-etching adhesives (Clearfil S3 Bond - S3, Clearfil Protect Bond – ProtectB and One-Up Bond F Plus - OneUp) were applied to the cavities, which had the enamel margins either etched with 35% phosphoric acid or left unecthed. The cavities were incrementally restored with TPH3 restorative composite, which was light-activated using Light Emitted by Diode (Hadii-Cal) or Halogen Lamp (Optilux 501). Epoxy resin replicas were obtained from the restored teeth, which were then submitted to thermal cycling. Afterwards, new replicas were obtained and the gaps at the resin composite/enamel margin interface were analyzed by Scanning Electronic Microscopy. Half sample was randomly tested for microtensile bond strength test (n=6) while the other half had the composite tested for KHN (n=6). Results: The etched enamel contributed to avoid gap formation only when OneUp adhesive system was used. No significant difference in MTBS values was found among groups. For KHN analysis, all restorations light-activated with LED showed higher KHN values than those light-activated with halogen lamps. In addition, the resin composites used to restore cavities with acid etched enamel margins showed higher KHN means than those used in cavities having unteched enamel margins. Conclusion: The resin composite bonded to cavities with S3 showed the lowest KHN values at the intermediate and bottom. ProtectB showed no significant differences for the different surface depths

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 37A degrees 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 a parts per thousand currency signaEuro parts per thousand 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.CAPE

Effects of residual contamination on mechanical properties and real-time conversion of etch-and-rinse adhesive / Efeitos da contaminação residual nas propriedades mecânicas e na cinética de conversão de adesivos convencionais

Introduction: An ideal hybrid layer should have water and solvents completely replaced by resin monomers, thus creating an interdiffusion zone with collagen and resin, and guaranteeing resistance and adequate mechanical properties to resist the challenges incurred in restoration. Objective: To evaluate the influence of residual contamination by different concentrations of water, ethanol and chlorexidine on mechanical properties and conversion of two etch-and-rinse adhesives. Method: Bar specimens of a model adhesive (M1) and a commercial Scotchbond MP adhesive (SBMP) were prepared and submitted to flexural strength (FS), elastic modulus (E), conversion degree (DC) and the kinetics of cure (K) evaluation. The real-time polymerization (RP) was monitored for 120 seconds. The data were statistically analyzed by two-way ANOVA and Tukey ?s test (?=0.05). Results: All solutions showed a decrease in FS and E values. For M1 adhesive, this decrease could be noted with increase of all dilutions tested. A decrease in DC values also was noted as dilutions increased, independent of solution tested. For SBMP adhesive, the mechanical properties were affected more by water and chlorexidine solutions and, it was noted an increase in DC with the increase of solution, especially for ethanol. For K test, adding water to adhesives, a progressive decrease could be noted on graphics. Conclusions: So a reduction in mechanical properties of adhesive solutions could be noted when extreme amounts of residual solutions. Nevertheless, at lowest concentrations, ethanol and chlorexidine seems not interfere on K and RP of adhesives. 

Physical evaluation of the luting systems for veneer ceramic after aging / Avaliação física dos sistemas de cimentação para faceta cerâmica após envelhecimento

The aim of this in vitro study was evaluated the amount of color change and degree of conversion of the luting systems for ceramic veneer cementation. Forty-eight human incisors were randomly divided into six groups (n=8) according to the bonding procedure: RelyX Veneer/Single Bond 2; RelyX ARC/Single Bond 2; Filtek Z350 XT Flowable /Single Bond 2; Variolink Veneer/Tetric N-Bond; Variolink II/Tetric N-Bond; Tetric N-Flow/Tetric N-Bond. Ceramic veneers (IPS Empress Esthetic) were cemented using the different bonding procedures. Color differences of the ceramic surface after cementation and 300 h(150kJ/m2) of UV aging test, were examined with a colorimeter. Fourier transform infrared spectroscopy (FT-IR) was used to evaluate the degree of conversion for each luting system. Data were analyzed with one-way ANOVA and Tukey's test (α=0.05). All the luting systems demonstrated significant changes in color stability. The ΔE of the systems ranged from 6,11 to 9,33. Tetric N-Flow and RelyX Veneer showed the highest degree of conversion, while lowest values were found for RelyX ARC. All luting systems demonstrated clinically unacceptable (ΔE≥ 3.3) color changes. Despite to the dual cure of the RelyX ARC luting cement, it showed the lowest degree of conversion values, while Tetric N-Flow and RelyX Veneer presented the highest and similar degree of conversion

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

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)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 37A degrees 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 a parts per thousand currency signaEuro parts per thousand 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.271145151Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

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

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 degrees 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 SEAS80894394