Effect of Nisin-based pretreatment solution on dentin bond strength, antibacterial property, and MMP activity of the adhesive interface

OBJECTIVE

To evaluate the effect of a Nisin-based dentin pretreatment solution on microtensile bond strength, antibacterial activity, and matrix metalloproteinase (MMP) activity of the adhesive interface.

MATERIALS AND METHODS

100 human molars were sectioned to expose dentin. The teeth were assigned to five groups (n = 20), according to the dentin pretreatment: 0.5%, 1.0%, or 1.5% Nisin; 0.12% chlorhexidine (positive control), and no solution (negative control), and divided into 2 subgroups: no aging, and thermomechanical aging. Specimens were etched with 37% H3PO4 for 15 s and submitted to the dentin pretreatment. Then, they were bonded with an adhesive (Adper Single Bond 2) and a resin composite for microtensile bond strength (μTBS) evaluation. Antibacterial activity against Streptococcus mutans was qualitatively examined using an agar diffusion test. Anti-MMP activity within hybrid layers was examined using in-situ zymography. Data were analyzed with two-factor ANOVA and post-hoc Tukey's test (α = 0.050).

RESULTS

For μTBS, significant differences were identified for the factors "solutions" (p = 0.002), "aging" (p = 0.017), and interaction of the two factors (p = 0.002). In the absence of aging, higher μTBS was observed for the group 0.5% Nisin. In the presence of aging, all groups showed similar μTBS values. All Nisin concentrations were effective in inhibiting the growth of S. mutans. Endogenous MMP activity was more significantly inhibited using 0.5% and 1.0% Nisin (p < 0.050).

CONCLUSION

0.5% and 1.0% Nisin solutions do not adversely affect resin-dentin bond strength and exhibit a potential bactericidal effect against S. mutans. Both concentrations effectively reduce endogenous gelatinolytic activity within the hybrid layer.

CLINICAL RELEVANCE

The use of 0.5% and 1.0% Nisin solutions for dentin pretreatment potentially contributes to preserving the adhesive interface, increasing the longevity of composite restorations.

Bond Stability of a Universal Adhesive System to Eroded/Abraded Dentin After Deproteinization

OBJECTIVE

Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (μTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization.

METHODS

Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for μTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C).

RESULTS

Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p=0.0007). Higher μTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate μTBS values similar to that of the E and EA groups for both bond strategies.

CONCLUSIONS

Erosion and erosion/abrasion did not significantly influence the immediate μTBS to dentin. Artificial aging reduced μTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.

The combined effect of food-simulating solutions, brushing and staining on color stability of composite resins

Objective: This study evaluated the effect of food-simulating media associated with brushing and coffee staining on color stability of different composite resins.

Materials and methods: Eighty specimens were prepared for each composite: Grandio SO (Voco), Amaris (Voco), Filtek Z350XT (3M/ESPE), Filtek P90 (3M/ESPE). They were divided into four groups according to food-simulating media for 7 days: artificial saliva (control), heptane, citric acid and ethanol. The composite surface was submitted to 10,950 brushing cycles (200 g load) in an automatic toothbrushing machine. The specimens were darkened with coffee solution at 37 °C for 24 h. After each treatment, color measurements were assessed by spectrophotometry, using CIE L*a*b* system. The overall color change (ΔE) was determined for each specimen at baseline (C1) and after the treatments (food-simulating media immersion/C2, brushing/C3 and dye solution/C4). Data were analyzed by two-way repeated measures ANOVA and Tukey’s tests (p < .05).

Results: The results of RM-ANOVA showed significant differences for composites (p = .001), time (p = .001) and chemical degradation (p = .002). The mean of ΔE for composites were: Z350XT (5.39)^a, Amaris (3.89)^b, Grandio (3.75)^bc, P90 (3.36)^c. According to food-simulating media: heptane (4.41)^a, citric acid (4.24)^a, ethanol (4.02)^ab, artificial saliva (3.76)^b. For the treatments: dye solution (4.53)^a, brushing (4.26)^a, after food-simulating media (3.52)^b.

Conclusions: The composite resin Filtek Z350XT showed significantly higher staining than all other composite resin tested. The immersion in heptane and citric acid produced the highest color alteration than other food-simulating media. The exposure of samples to brushing protocols and darkening in coffee solution resulted in significant color alteration of the composite resins.

Effect of chlorhexidine, green tea and egcg as therapeutic primers to increase the durability of resin-dentin bond

Objective - This study evaluated the effect of 0.2% chlorhexidine gluconate solution (CHX), green tea and active epigallocatechin-gallate (EGCG) used as therapeutic primers on the long-term bond strength of etch-and-rinse adhesive to dentin. Material and Methods - Eighty bovine incisors were worn to expose an area of dentin, that were acid-etched (37% phosphoric acid) and rinsed.  The teeth were divided into 4 groups (n = 20): Group C (Control) - Single Bond; Group CHX - 0.2% CHX for 30s + Single Bond;  Group EGCG - active EGCG gel at 10 µM for 30 s + Single Bond;  Group GT - aqueous green tea for 30s + Single Bond. Blocks of composite were fabricated and stored for 24 h or 6  months, sectioned into beams  and  submitted  to  microtensile  tests. Results  were  analyzed  by  two-way  ANOVA  and Tukey’s test (5%).  Results - Mean (±SD) values (in MPa) were as follow: CHX (24 h) – 41.76 (±2.62); C (24 h) - 40.81 (±3.35); GT (24 h): 37.38(2.98); CHX (6 months) - 36.04 (±3.52); EGCG (24h) - 35.91 (±4.82); EGCG (6 months) - 35.75 (±4.44); GT (6 months) - 31.95 (±3.40); C (6 months): 30.05 (±1.54). Conclusion - EGCG produced resin-dentin bonds that did not change after 6 months water storage but it decreased the immediate bond strength when compared to control and chlorhexidine groups.Keywords: Tensile bond strength; Dentin; Total-etch adhesives; Chlorhexidine gluconate; Green tea.

Evaluation of bond strength of composite resin to enamel demineralized, exposed to remineralization and subjected to caries infiltration

Objective: To evaluate the bond strength between resin composite and different enamel substrates: sound enamel; demineralized enamel submitted or not to remineralization; and demineralized enamel infiltrated with aninfiltrating resin. Material and Methods: 120 bovine teeth were selected, the root portion was removed and the enamel finished. Specimens were divided into the following groups: (A) Control (n=24): adhesively treated and restored; (B) (n=96): the samples were immersed in a demineralization solution to create white spot lesions and divided into four subgroups: (B1) demineralized enamel; (B2) samples were stored in artificial saliva (8 weeks); (B3) samples were stored in a 0.05% sodium fluoride solution (1 min day/8 weeks); (B4) samples were treated with an infiltrant resin (Icon, DMG). The groups were treated with one of the following adhesives: Clearfil S3 Bond Plus (Kuraray) or Single Bond Universal (3M ESPE), followed by the resin composite application (Filtek Z 350 XT, 3M ESPE). The specimens were submitted to thermalcycling aging (10,000 ×; 2±5ºC, 50±55ºC and 37°± 2°C). The specimens were sectioned into prism shapes with ~1mm² of base and submitted to microtensile test. The collected data were submitted to ANOVA and Tukey´s test (?= 5%). Results: The Means (±SD) in MPa were: Clearfill S3 Bond Plus: Control (17.17±3.52); B1 (11.60±0.74); B2 (6.83±1.87); B3 (8.38±1.59) and B4 (27.00±1.76); Single Bond Universal: Control (26.26±3.19); B1 (10.94±2.00); B2 (11.05±1.74); B3 (15.63±1.25) and B4 (22.60±2.29). Conclusion: The surface infiltrated with an infiltrating resin (Icon) did not negatively affect the bond strength between resin composite and enamel. The demineralized and remineralized groups with sodium fluoride and artificial saliva presented statistically lower results when compared to the other groups.  

Adhesive Systems as an Alternative Material for Color Masking of White Spot Lesions: Do They Work?

PURPOSE

To evaluate the color masking effect of infiltration treatment of artificial white spot lesions (AWSL) using a dedicated resin in comparison to different adhesive systems.

MATERIALS AND METHODS

Enamel/dentin specimens were obtained from bovine incisors and baseline color was assessed using a reflectance spectrophotometer, according to the CIE L*a*b* system. AWSL were produced using a buffered acid solution and a new color evaluation was performed. The specimens were divided into 8 groups: control: artificial saliva changed daily for 7 days; IC: infiltrating resin Icon; EC: EquiaCoat; FU: Futurabond U; SBU: Single Bond U; SBMP: Scotchbond MP; OB: OptibondFL; BF: Bioforty. After the treatments, the color was evaluated again and the values for the parameters ΔL (change in lightness), Δa (change in chroma), Δb (change in hue), and ΔE (general color difference) were calculated in relation to baseline. Data were analyzed by one-way ANOVA and Tukey's tests.

RESULTS

After treatment, ANOVA showed significant differences for all parameters (p = 0.001). Tukey's test showed the greatest lightness reduction (ΔL) for the IC group, followed by EC, FU, and SBU. The SBMP, OB, and BF groups were similar to the control. For Δb values, all groups showed differences in relation to the control, with no differences between them. In relation to ΔE, all groups showed differences in relation to the control (ΔE = 5.24), with no significant differences between them. ΔE values after application of all resinous materials were lower than the threshold of 3.7, indicating effective color masking.

CONCLUSIONS

The Icon infiltrant produced a greater lightness reduction of white lesions (ΔL). For general color difference (ΔE), all the resinous materials tested were able to color mask artificial AWSL.

Mechanical properties of the bond interface associated with nd:yag laser

ABSTRACTObjective:This study evaluated the hardness and modulus of elasticityof the dentin bond interface using total-etch (Single Bond /SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with Nd:YAG Laser irradiation through the unpolymerized adhesives.Material and Methods: The occlusal surfaces of 12 human third molars were ground until superficial dentin was exposed. A standardized circular cavity was performed on the occlusal surface. Specimens were sectioned in the mesio-distal direction, and the 24 hemi-crowns were divided into four groups: Group SB/Control - SB + polymerization; Group SB/Laser - SB + Nd:YAG laser (174.16J/cm2/60s/non-contact) + polymerization; Group CSEB/Control – CSEB + polymerization; Group CSEB/Laser - CSEB + Nd:YAG laser (174.16J/cm2/cm2/60s/non-contact) + polymerization. Composite were placed in the cavities and polymerized. The specimens were immersed in distilled water and stored in an oven at 37ºC for 24h and then submitted to nanoindentation in a Nano Indenter® XP appliance. Results: The results were submitted to ANOVA, Tukey’s test and Student's-t test (p < 0.05). Conclusão: It was concluded that the application of the Nd:YAG laser in both adhesive systems did not changed the hybrid layer hardness; however, it increases the modulus of elasticity in the hybrid layer for both adhesives tested and it maybe preserves the integrity of the adhesive interface and its durability. Clinical relevance: The application of Nd:YAG laser prior to photopolymerization of adhesive systems can increase the modulus of elasticity in the hybrid layer and may contribute to stress distribution in the adhesive interface during the polymerization preserving the integrity of the adhesive interface and its durability.

Longitudinal Evaluation of Bond Strength to Enamel of Dental Adhesive Systems Associated with Nd:YAG Laser

OBJECTIVES

This study evaluated the durability of bond strength to enamel using total-etch (Single Bond/SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with neodymium:yttrium-aluminu-garnet (Nd:YAG) laser irradiation through the uncured adhesives.

METHODS

Bovine incisors were worn to expose an area of enamel and were divided into four groups: group 1 (control) SB + polymerization; group 2 (control) CSEB + polymerization; group 3 (laser) - SB + Nd:YAG laser (174.16 J/cm(2)) + polymerization; and group 4 (laser) CSEB + Nd:YAG (174.16 J/cm(2)) + polymerization. Blocks of composite were fabricated and stored for 24 hours or 12 months, sectioned into beams, and submitted to microtensile tests. Results were analyzed by three-way analysis of variance (ANOVA) (adhesive, technique, and storage time) and Tukey tests.

RESULTS

ANOVA revealed significant differences for adhesive × technique and technique × storage time (p<0.05). The mean values (MPa) for interaction adhesive × technique (standard deviation) were as follows: SB/control = 35.78 (6.04)a; SB/laser = 26.40 (7.25)b, CSEB/control = 26.32 (5.71)b, CSEB/laser = 23.90 (7.49)b. For interaction technique × storage time the mean values were as follows: control/24 hours = 32.58 (6.49)a; control/12 months = 29.52 (8.38)a; laser/24 hours = 29.37 (5.71)a; laser/12 months = 20.92 (6.5)b. Groups with the same letters showed no statistically significant differences.

CONCLUSION

Scanning electron microscope analysis showed evident areas of micromorphological alterations in lased samples after 12 months of water storage. Nd:YAG laser irradiation of enamel through unpolymerized total-etch adhesive significantly reduced bond strength compared with the control. Bond strength decreased when enamel samples irradiated with Nd:YAG laser through unpolymerized adhesives were stored in water for 12 months.

Influence of pH on the Effectiveness of Hydrogen Peroxide Whitening

Objective

To evaluate the influence of pH on the bleaching effect of hydrogen peroxide on chromogen agents.

Method

Hydrogen peroxide 50% was mixed with red wine or with an alcoholic solution of tobacco in glass cuvettes, resulting in final peroxide concentrations of 16.97% and 21.12%, respectively. The pH of this mixture was measured and adjusted with 3.3 M HCl solution or 2.5 M NaOH solution to obtain the final pH values of 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0. After mixing, the color of these solutions was evaluated in a reflectance spectrophotometer; readings were repeated after 10 minutes for the wine solution and 20 minutes for the tobacco solution. Ten samples were prepared for each solution at each pH. Color changes (Delta E) were calculated. The data were statistically analyzed using analysis of variance one-way and Tukey tests, with a significance level of 5%.

Results

There were significant differences among the different pH values for the wine and tobacco solutions (p=0.0001). The Tukey test showed that for both solutions, pH 9.0 resulted in a significantly greater bleaching effect than the other values tested.

Conclusion

The efficacy of hydrogen peroxide bleaching is directly proportional to the increase in its pH.

Comparison of different dentin pretreatment protocols on the bond strength of glass fiber post using self-etching adhesive

INTRODUCTION

This study compared the influence of different irrigants with and without ultrasound or laser irradiation on the bond strength of glass fiber posts using a self-etching adhesive in a supplementary dentin pretreatment.

METHODS

Ninety bovine incisor roots were divided into 3 groups according to the irrigant tested: 2% chlorhexidine (CHX) (n = 30); 2.5% sodium hypochlorite (NaOCl) (n = 30), and saline solution (control) (n = 30). Each group was randomly divided into 3 subgroups according to the supplementary dentin pretreatment: ultrasound, Nd:YAG laser, and nonsupplemented (control). A self-etching adhesive system (Futurabond DC; VOCO GmbH, Cuxhaven, Germany) was used, and the glass fiber posts were cemented with dual-cure epoxy-based luting agent (Bifix QM, VOCO GmbH). All roots were sectioned transversely, and the push-out test was performed. Failure mode analysis was also evaluated.

RESULTS

Bond strength decreased significantly after the use of 2.5% NaOCl in all root thirds (P < .05). CHX showed no difference in the mean bond strength value compared with saline solution (P > .05). The supplementary dentin pretreatment using the Nd:YAG laser or ultrasound did not improve the bond strength values for both NaOCl and CHX (P > .05). Moreover, the apical third exhibited the lowest mean bond strength values (P < .05). Analysis indicated that the predominant failure mode was the mixed type.

CONCLUSIONS

Regardless of the irrigant used, the supplementary dentin pretreatment with ultrasound or laser irradiation showed no improvement in bond strength. Also, the use of NaOCl decreased the bond strength of glass fiber posts using a self-etching adhesive system, whereas CHX preserved it.

Effect of hydrogen peroxide concentration on enamel color and microhardness

OBJECTIVES

The aim of this study was to investigate the effect of hydrogen peroxide gels with different concentrations (20%, 25%, 30%, and 35%) on enamel Knoop microhardness (KNH) as well as on changes in dental color (C).

METHODS

Cylindrical specimens of enamel/dentin (3-mm diameter and 2-mm thickness) were obtained from bovine incisors and randomly divided into six groups (n=20), according to the concentration of the whitening gel (20%, 25%, 30%, 35%, control, thickener). After polishing, initial values of KNH0 and color measurement, assessed by spectrophotometry using the CIE L*a*b* system, were taken from the enamel surface. The gels were applied on the enamel surface for 30 minutes, and immediate values of KNHi were taken. After seven days of being stored in artificial saliva, new measures of KNH7 and color (L7* a7* b7*, for calculating ΔE, ΔL, and Δb) were made. Data were submitted to statistical analysis of variance, followed by Tukey test (p<0.05).

RESULTS

Differences in gel concentration and time did not influence the microhardness (p=0.54 and p=0.29, respectively). In relation to color changes, ΔE data showed that the 35% gel presented a higher color alteration than the 20% gel did (p=0.006).

CONCLUSION

Bleaching with 35% hydrogen peroxide gel was more effective than with the 20% gel, without promoting significant adverse effects on enamel surface microhardness.

New Trends in Dentin Bonding: Treatment with chlorhexidine, hyaluronic acid, vitaminc C and green tea

Objective: The aim of this study was to evaluate the bond strength of dentin treated with chlorhexidine, hyaluronic acid, vitamin C and green tea. Material and Methods: The roots of 50 bovine teeth were removed and buccal coronal dentin was exposed. After acid-etching, the specimens were divided into 5 groups (n = 10), according to the dentin treatment strategy: CO - untreated dentin; CHX - treated with 2 wt% chlorhexidine for 30 sec; HA - treated with 1 wt% hyaluronic acid for 30 sec; VC - treated with 10 wt% vitamin C for 30 sec; GT - treated a 1% green tea extract for 30 sec.  Adper Single Bond was then applied to the treated according to the manufacturer's recommendations. The specimens were restored with a 4-mm thick layer of the resin composite, which was polymerized for 40 sec. The specimens were stored in distilled water at 37°C for 24 h and sectioned into 1x1 mm2 sticks containing the adhesive interface. Microtensile bond strength testing was performed with a universal testing machine at a cross-head speed of 1.0 mm/min. Results: The results were analyzed with one-factor ANOVA and Tukey’s multiple comparison tests. GT group presented the highest values bond strength (29.4±3.1)a, but no significant difference compared to the other experimental groups HA(26.7±3.1)ab, CHX(25.4±2.6)ab and VC(22.4±6.0)b. Bond strengths of experimental groups were not significantly different from the CO. Conclusion: Immediate bond strength was preserved after acid-etched dentin was treated.Keywords: Chlorhexidine. Hyaluronic acid. Vitamin C. Green tea. Bond strength.

Oral Health Longitudinal Evaluation of students from a public school after guidance and implementaion of preventitive measures

Objective: To assess longitudinally the DMFT, plaque and gingival rates of children and teenagers from a public school in São José dos Campos, Brazil, after performing a preventive and motivational program through the University Extension program of School of Dentistry of Institute of Science and Technology of São José dos Campos – UNESP. Materials and Methods: 300 students were randomly selected and divided into three groups, Group 1: 100 children from 2nd to 5th grade of elementary school, Group 2: 100 children from 6th to 9th grade of elementary school; Group 3: 100 teenagers from first to third year of high school. A questionnaire was used to evaluate knowledge about oral habits and general oral health of students. Clinical examinations were performed to assess the gingival, DMFT and plaque index in the initial time (t0), 1 year (t1) and 2 years (t2). The questionnaire and clinical examination results led to implementation of a scheme to promote oral health throughout the school years. The collected data were statistically analyzed. Results: Mean values for DMFT were: Group 1: t0 = 2.3 / t1 = 2.28 / t2 = 1.88, group 2: t0 = 1.81 / t1 = 1.56 / t2 = 1.51 and Group 3: t0 = 1.92 / t1 = 2.61/ t2 = 1.86; for dental plaque index: group 1: t0 = 3.83/ t1 = 2.62/ t2 = 2.30, group 2: t0 = 2.06 / t1 = 3.24 / t2 = 1.39; Group 3: t0 = 2.27 / t1 = 0.94 / t2 = 0.8, and the gingival index: group 1: t0 = 1.31 / t1 = 0.79 / t2 = 0.96, group 2: t0 = 1.27 / t1 = 0.84 / t2 = 0.38; group 3: t0 = 1.21 / t1 = 0.82 / t2 = 0.23. Conclusion: There was a significant decrease in all evaluated indexes after 2 years of program, confirming thus the importance of systematic implementation of preventive measures.

Influence of CVD diamond tips and Er:YAG laser irradiation on bonding of different adhesive systems to dentin

AIM

The aim of this study was to compare the microtensile bond strength of three adhesive systems, using different methods of dentin preparation.

MATERIALS AND METHODS

A hundred and eight bovine teeth were used. The dentin from buccal face was exposed and prepared with three different methods, divided in 3 groups: Group 1 (DT)- diamond tip on a high-speed handpiece; Group 2 (CVD)-CVD tip on a ultrasonic handpiece; Group 3 (LA)-Er: YAG laser. The teeth were divided into 3 subgroups, according adhesive systems used: Subgroup 1-Adper Single Bond Plus/3M ESPE (SB) total-etch adhesive; Subgroup 2-Adper Scotchbond SE/3M ESPE (AS) selfetching adhesive; Subgroup 3-Clearfil SE Bond/Kuraray (CS) selfetching adhesive. Blocks of composite (Filtek Z250-3M ESPE) 4 mm high were built up and specimens were stored in deionized water for 24 hours at 37°C. Serial mesiodistal and buccolingual cuts were made and stick-like specimens were obtained, with transversal section of 1.0 mm(2). The samples were submitted to microtensile test at 1 mm/min and load of 10 kg in a universal testing machine. Data (MPa) were subjected to ANOVA and Tukey's tests (p < 0.05).

RESULTS AND CONCLUSION

Surface treatment with Diamond or CVD tips associated with Clearfil SE Bond adhesive produced significantly lower bond strength values compared to other groups. Surface treatment with Er: YAG laser associated with Single Bond Plus or Clearfil SE Bond adhesives and surface treatment with CVD tip associated with Adper Scotchbond SE adhesive produced significantly lower bond strength values compared to surface treatment with diamond or CVD tips associated with Single Bond Plus or Adper Scotchbond SE adhesives.

CLINICAL SIGNIFICANCE

Interactions between laser and the CVD tip technologies and the different adhesive systems can produce a satisfactory bonding strength result, so that these associations may be beneficial and enhance the clinical outcomes.

Efficacy of Mouth Rinses and Toothpaste on Tooth Whitening

Objectives

People increasingly desire tooth whitening. Considering the wide range of whitening products on the market, this study evaluated the efficacy of whitening toothpastes and mouth rinses compared with the 10% carbamide peroxide (CP) whitening gel.

Methods

We obtained 120 cylindrical specimens from bovine teeth, which were darkened for 24 hours in a coffee solution. The color measurement was performed by a spectrophotometer using the CIE L*a*b* system, and specimens were divided into six groups according to the use of the following agents: group 1, conventional fluoridated toothpaste; group 2, Close Up White Now; group 3, Listerine Whitening; group 4, Colgate Plax Whitening; group 5, experimental mouth rinse with Plasdone; and group 6, 10% CP Whiteness Perfect. After the simulation of 12 weeks of treatment for groups 1 to 5 and 14 days of treatment for group 6, the specimens were subjected to a new color reading.

Results

Data were subjected to one-way analysis of variance (α=0.05), which showed significant differences among groups after 12 weeks for ΔE (p=0.001). Results of the Tukey test revealed that groups 3, 4, and 6 presented significantly higher color alteration than groups 1, 2, and 5.

Conclusions

The whitening toothpaste Close Up White Now and the experimental mouth rinse with Plasdone showed similar color alteration as conventional toothpaste after a 12-week treatment simulation. These groups presented significantly lower color alteration compared with whitening mouth rinses Listerine and Colgate Plax Whitening, which showed similar results to those observed after 14 days of bleaching with 10% CP treatment.

Influence of Different Surface Treatments on Bond Strength of Resin Composite Using the Intrinsic Characterization Technique

Objective: This study evaluated the influence of different surface treatments on the resin bond strength/light-cured characterizing materials (LCCMs), using the intrinsic characterization technique. The intrinsic technique is characterized by the use of LCCMs between the increments of resin composite (resin/thin film of LCCM/external layer of resin covering the LCCM).

Materials and Methods: Using a silicone matrix, 240 blocks of composite (Z350/3M ESPE) were fabricated. The surfaces received different surface treatments, totaling four groups (n=60): Group C (control group), no surface treatment was used; Group PA, 37% phosphoric acid for one minute and washing the surface for two minutes; Group RD, roughening with diamond tip; and Group AO, aluminum oxide. Each group was divided into four subgroups (n=15), according to the LCCMs used: Subgroup WT, White Tetric Color pigment (Ivoclar/Vivadent) LCCM; Subgroup BT, Black Tetric Color pigment (Ivoclar/Vivadent) LCCM; Subgroup WK, White Kolor Plus pigment (Kerr) LCCM; Subgroup BK, Brown Kolor Plus pigment (Kerr) LCCM. All materials were used according to the manufacturer's instructions. After this, block composites were fabricated over the LCCMs. Specimens were sectioned and submitted to microtensile testing to evaluate the bond strength at the interface. Data were submitted to two-way analysis of variance (ANOVA) (surface treatment and LCCMs) and Tukey tests.

Results: ANOVA presented a value of p&lt;0.05. The mean values (±SD) for the factor surface treatment were as follows: Group C, 30.05 MPa (±5.88)a; Group PA, 23.46 MPa (±5.45)b; Group RD, 21.39 MPa (±6.36)b; Group AO, 15.05 MPa (±4.57)c. Groups followed by the same letters do not present significant statistical differences. The control group presented significantly higher bond strength values than the other groups. The group that received surface treatment with aluminum oxide presented significantly lower bond strength values than the other groups.

Conclusion: Surface treatments of composite with phosphoric acid, diamond tip, and aluminum oxide significantly diminished the bond strength between composite and the LCCMs.

Prevalence of chewing side preference in the deciduous, mixed and permanent dentitions

AIM

This study evaluated the prevalence of the chewing side preference (CSP) in the deciduous, mixed and permanent dentitions.

MATERIALS AND METHODS

Three-hundred subjects were divided in three groups (n = 100): Group 1 - children with deciduous dentition; group 2-children with mixed dentition; group 3 - subjects with permanent dentition. The CSP was determined using a direct method (visual observation) developed by McDonnell et al. (2004). Descriptive statistic was used to observe the prevalence of CSP. The Pearson's Chi-square was used to investigate signicant associations between gender, presence of CSP and preferred side (right/left).

RESULTS AND CONCLUSION

Eighty-seven percent of group 1 had a CSP. Eighty-two percent of group 2 had a CSP. Seventy-six percent of group 3 had a CSP. There was no statistically significant association between presence of CSP and gender in all groups. There was no statistically significant association between preferred side (right/left) and gender in all groups.

CLINICAL SIGNIFICANCE

There is a higher prevalence of subjects in deciduous, mixed and permanent dentition that presented chewing side preference. The early diagnosis of the presence of chewing side preference can prevent the unilateral chewing pattern with prophylactic therapy applied to the first teeth (deciduous).

Effect of biomimetic remineralization on the dynamic nanomechanical properties of dentin hybrid layers

The mineral and organic phases of mineralized dentin contribute co-operatively to its strength and toughness. This study tested the null hypothesis that there is no difference in nano-dynamic mechanical behavior (complex modulus-E*; loss modulus-E''; storage modulus-E'; in GPa) of dentin hybrid layers (baseline: E*, 3.86 ± 0.24; E'', 0.23 ± 0.05; E', 3.85 ± 0.24) created by an etch-and-rinse adhesive in the presence or absence of biomimetic remineralization after in vitro aging. Using scanning probe microscopy and nano-dynamic mechanical analysis, we demonstrated that biomimetic remineralization restored the nano-dynamic mechanical behavior of heavily remineralized, resin-sparse regions of dentin hybrid layers (E*, 19.73 ± 3.85; E'', 8.75 ± 3.97; E', 16.02 ± 2.58) to those of the mineralized dentin base (E*, 19.20 ± 2.42; E'', 6.57 ± 1.96; E', 17.39 ± 2.0) [p > 0.05]. Conversely, those resin-sparse, water-rich regions degraded in the absence of biomimetic remineralization, with significant decline [p < 0.05] in their complex and storage moduli (E*, 0.83 ± 0.35; E'', 0.88 ± 0.24; E', 0.62 ± 0.32). Intrafibrillar apatite deposition preserves the integrity of resin-sparse regions of hybrid layers by restoring their nanomechanical properties to those exhibited by mineralized dentin.

The Influence of Chemical Activation on Tooth Bleaching Using 10% Carbamide Peroxide

If a chemical agent were able to accelerate the effects of bleaching agents on tooth structure, one could reduce treatment time or diminish the daily time spent on the bleaching procedures.

pH-changes during intracoronal bleaching: an in vivo study

OBJECTIVES

This study aimed to measure pH changes during 14 days intracoronal bleaching with hydrogen peroxide/sodium perborate and carbamide peroxide/sodium perborate.

MATERIALS AND METHODS

Twenty patients presenting endodontically treated central maxillary incisors with color alterations were divided in two groups (n = 10): Group CP + SP: 37% carbamide peroxide + sodium perborate paste; Group HP + SP: 30% hydrogen peroxide + sodium perborate paste. The pH values were measured using a digital microprocessor at different times: Baseline, 2, 7 and 14 days. Data were analyzed with two-way ANOVA followed by Tukey's test (α = 0.05).

RESULTS

ANOVA showed p < 0.00 which indicated significant difference between the groups. The mean values (± sd) and the results of the Tukey´s test were: HP + SP/14 days-7.98 (±0.58)a; HP + SP/7 days-8.59 (±0.18)b; HP + SP/2 days- 8.83 (±0.32)bc; HP + SP/Baseline-8.83 (±0.01)bc; CP + SP/ Baseline-8.89 (±0.01)bc; CP + SP/14 days-9.11 (±0.58)cd; CP + SP/7 days-9.54 (±0.16)de; CP + SP/2 days-9.66 (±0.08) de. The group HP + SP resulted in significantly lower pH values compared with group CP + SP.

CONCLUSION

It can be concluded that both associations showed alkaline pH values; however, there was significant reduction in the pH values of the 30% hydrogen peroxide associated with sodium perborate after 14 days.

CLINICAL SIGNIFICANCE

The association of hydrogen peroxide and carbamide peroxide with sodium perborate paste presented alkaline characteristics during the 14-day evaluated period. Thus, regarding pH changes, both associations can be considered safe as intracoronal bleaching agents.

The critical barrier to progress in dentine bonding with the etch-and-rinse technique

OBJECTIVES

The lack of durability in resin-dentine bonds led to the use of chlorhexidine as MMP-inhibitor to prevent the degradation of hybrid layers. Biomimetic remineralisation is a concept-proven approach in preventing the degradation of resin-dentine bonds. The purpose of this study is to examine the integrity of aged resin-dentine interfaces created with a nanofiller-containing etch-and-rinse adhesive after the application of these two approaches.

METHODS

The more established MMP-inhibition approach was examined using a parallel in vivo and in vitro ageing design to facilitate comparison with the biomimetic remineralisation approach using an in vitro ageing design. Specimens bonded without chlorhexidine exhibited extensive degradation of the hybrid layer after 12 months of in vivo ageing.

RESULTS

Dissolution of nanofillers could be seen within a water-rich zone within the adhesive layer. Although specimens bonded with chlorhexidine exhibited intact hybrid layers, water-rich regions remained in those hybrid layers and degradation of nanofillers occurred within the adhesive layer. Specimens subjected to in vitro biomimetic remineralisation followed by in vitro ageing demonstrated intrafibrillar collagen remineralisation within hybrid layers and deposition of mineral nanocrystals in nanovoids within the adhesive.

CONCLUSIONS

The impact was realized by understanding the lack of an inherent mechanism to remove water from resin-dentine interfaces as the critical barrier to progress in bonding with the etch-and-rinse technique. The experimental biomimetic remineralisation strategy offers a creative solution for incorporating a progressive hydration mechanism to achieve this goal, which warrants its translation into a clinically applicable technique.

Assessment of color fidelity of several composite resins compared to their Vita Classical shade registration

This study compared the color fidelity of different composite resins with their registration in the Vita Classical Shade Guide. Using a prefabricated Teflon mold, 120 specimens were divided into four groups (n = 30), according to the resin tested. Three subgroups (n = 10) were prepared for each resin group; these subgroups tested enamel shade, dentin shade, and enamel and dentin shade. Three measurements were performed to verify whether the tooth shade matched that of the Vita Classical Shade Guide. The color was evaluated and the shade variations were calculated. The data were submitted to a three-way ANOVA test (time, color match, and composite type), followed by Tukey's test. It was concluded that all composite resins showed color differences in relation to the Vita Classical Shade Guide.

Clinical evaluation of two packable resin-based composite restorations: a three-year report

This randomized clinical trial sought to evaluate the performance of two packable composites over a period of 36 months. A total of 39 Class I and II restorations were placed in the permanent teeth of 20 patients. Using United States Public Health Services criteria, two investigators evaluated the restorations immediately after placement and again after 12 and 36 months, examining color match, marginal discoloration, marginal integrity, recurrent caries, proximal contact, anatomical shape, surface texture, and postoperative sensitivity. It was concluded that the packable composites evaluated showed satisfactory clinical performance after three years.

Longitudinal bond strength evaluation using the deproteinized dentin technique

This study evaluated bond strength to dentin as a result of storage time for conventional adhesive systems (with or without collagen) that had been deproteinized with 10% sodium hypochlorite (NaOCl). For this study, 72 human molars were sectioned in a mesiodistal axial plane and embedded in acrylic resin; at that point, the vestibular and lingual surfaces were worn down with abrasive paper. Acid etching was performed for 15 seconds (using 37% phosphoric acid) and the specimens were divided into 12 groups (n = 6), depending on the adhesive system used, the dentin treatment performed, and the length of evaluation (24 hours or six months). A resin composite was inserted over the prepared area with the aid of a metal matrix. Following a mechanical shear test, fractured surfaces were analyzed by stereomicroscope and the data were submitted to ANOVA and Tukey's test. It was concluded that the dentin deproteinization treatment with 10% NaOCl improved the bond strength in five of the six groups. The bond strength after 24 hours was significantly higher than the bond strength measured after six months. Of the three adhesive systems tested in this study, DenTASTIC UNO demonstrated the lowest bond strength.

Influence of matrix and insertion technique on the microleakage and microhardness of posterior composite restorations

This study sought to evaluate how the matrix and insertion technique affected microleakage and microhardness of posterior composite restorations. Class II preparations with the gingival margin in cementum were performed in 60 bovine teeth and divided into two groups: transparent matrix and reflective wedge (Group T) (n=20) and metallic matrix and wood wedge (Group M) (n=40). Cavities were restored and specimens were isolated with nail varnish, immersed in 0.2% Rhodamine B, and sectioned. Microleakage was evaluated under magnification (20x) and data were analyzed with one-way ANOVA. Microhardness was assessed at 1, 2, and 3 mm from the gingival wall and data were analyzed with two-way ANOVA. No significant difference was observed in terms of leakage. Significant differences were observed in terms of hardness for both factors, although no interaction was noted. It was concluded that the insertion technique had no influence on microleakage and that using a metallic matrix with oblique increments provided the highest hardness. There was no correlation between these two variables.

Effects of resinous monomers used in restorative dental modeling on the cohesive strength of composite resin

PURPOSE

The purpose of this study was to evaluate the cohesive strength of the composite using different resinous monomers to lubricate instruments used in the Restorative Dental Modeling Insertion Technique (RDMIT).

MATERIALS AND METHODS

The composite specimens were made by usinga prefabricated Teflon device. Different resinous monomers were used at the interface to lubricate the instruments, for a total of 72 specimens divided into 6 groups: (1) control group, no resinous monomer was used; (2) Composite Wetting Resin; (3) C & B Liquid; (4) Scotchbond Multi-Purpose Adhesive; (5) Adper Single Bond Adhesive; (6) Prime & Bond NT. Specimens were submitted to the circular area tensile test to evaluate the cohesive strength at the composite interfaces. Data were analyzed using ANOVA and Tukey's test (alpha = 0.05).

RESULTS

ANOVA showed a value of p < 0.0001, which indicated thatthere were significant differences amongthe groups. The means (SD) for the different groups were: Adper Single Bond Adhesive: 26 (12) a; control group: 28 (3) ab; Prime & Bond NT: 32 (12) ab; Composite Wetting Resin: 36 (9) abc; C&B Liquid: 38 (7) bc; Scotchbond Multi-Purpose Adhesive: 46 (10) c. Groups denoted with the same letters were not significantly different. Only Scotchbond Multi-Purpose Adhesive, used for direct restorations, had a statistically significantly higher bond strength than the control group, Adper Single Bond Adhesive, and Prime & Bond NT. Adper Single Bond with Adhesive showed a statistically significantly lower mean value than C & B Liquid.

CONCLUSION

The results of this study indicate that the resinous monomers used for lubricating the instruments in the RDMIT did not alter the mechanical properties of the composite, and therefore did not reduce the cohesive bond strength at the composite interfaces.