Morphological Evaluation of 2- and 1-step Self-etching System Interfaces with Dentin

Enamel and Dentin Etching with Glycolic, Ferulic, and Phosphoric Acids: Demineralization Pattern, Surface Microhardness, and Bond Strength Stability

This study evaluated the etching pattern, surface microhardness, and bond strength for enamel and dentin submitted to treatment with phosphoric, glycolic, and ferulic acids. Enamel and dentin blocks were treated with phosphoric, glycolic, and ferulic acid to evaluate the surface and adhesive interface by scanning electron microscopy (2000×). Surface microhardness (Knoop) was evaluated before and after etching, and microtensile bond strength was evaluated after application of a two-step adhesive system (Adper Single Bond 2, 3M ESPE) at 24 hours and 12 months storage time points. Analysis of variance (ANOVA) and Tukey's test showed a decrease in the microhardness values for both substrates after application of each acid (p<0.0001). The reduction percentage was significantly higher for enamel treated with phosphoric acid (59.9%) and glycolic acid (65.1%) than for ferulic acid (16.5%) (p<0.0001), and higher for dentin that received phosphoric acid (38.3%) versus glycolic acid (27.8%) and ferulic acid (21.9%) (p<0.0001). Phosphoric and glycolic acids led to homogeneous enamel demineralization, and promoted the opening of dentinal tubules, whereas ferulic acid led to enamel surface demineralization and partially removed the smear layer. The adhesive-enamel interface showed micromechanical embedding of the adhesive in the interprismatic spaces when phosphoric and glycolic acids were applied. Ferulic acid showed no tag formation. Microtensile bond strength at both time points, and for both substrates, was lower with ferulic acid (p=0.0003/E; p=0.0011/D; Kruskal Wallis and Dunn). The bond strength for enamel and dentin decreased when using phosphoric and glycolic acids at the 12-month time evaluation (p<0.05). Glycolic acid showed an etching pattern and microhardness similar to that of phosphoric acid. Ferulic acid was not effective in etching the enamel or dentin, and it did not provide satisfactory bond strength to dental substrates.

Comparative Evaluation of Microleakage of Flowable Composite Resin Using Etch and Rinse, Self-Etch Adhesive Systems, and Self-Adhesive Flowable Composite Resin in Class V Cavities: Confocal Laser Microscopic Study

The essential factor in determining the preservation of restoration is the marginal seal. Restoring cervical lesions with a resin composite has always been a challenge. Composite resins with various viscosities and different bonding systems are being researched to reduce the microleakage. Confocal laser scanning microscopy (CLSM) is the latest non-destructive technique for visualizing the microleakage. Objectives: To evaluate and compare the microleakage of Universal Flo composite resin (G-aenial) using etch and rinse adhesive system ER-2 steps (Adper Single Bond 2), self-etch adhesive system SE-1 step (G-Bond), and self-adhesive flowable composite resin (Constic) in Class V cavities using a confocal laser scanning microscope. Materials and Method: Class V cavities were prepared on 27 caries-free human extracted premolar teeth on the buccal and lingual surfaces with standardized dimensions of 2 mm height, width 4 mm, and a depth of 2 mm. After the cavity preparation, all teeth were randomly divided into three groups, namely Group-I: G-aenial Universal Flo with Single Bond 2 (n = 9 teeth); Group-II: G- aenial Universal Flo with G-Bond (n = 9 teeth), and Group-III: Constic (n = 9 teeth). The prepared and restored specimens were then subjected to thermocycling for 500 cycles in a water bath at 5 °C and 55 °C with a dwelling time of 30 s. The specimens were placed in 0.6% aqueous rhodamine dye for 48 h. Sectioning was carried out bucco-lingually and specimens were evaluated for microleakage under a confocal laser scanning microscope. Results: There was a significant difference (p = 0.009) in microleakage when comparing total etch and rinse, specifically between Adper Single Bond 2 ER-2 steps (fifth generation) and self-adhesive flowable composite resin, which is Constic. There was more microleakage in the self-etch bonding agent, particularly G-Bond, SE-1 step (seventh generation), when compared to ER-2 steps (fifth generation bonding agent); however, the results were not statistically significant (p = 0.468). The self-adhesive flowable composite resin showed more microleakage than SE-1 step and ER-2 steps. Conclusions: None of the adhesive systems tested were free from microleakage. However, less microleakage was observed in the total etch and rinse, especially Adper Single Bond 2 (ER-2 steps), than the self-etch adhesive system SE-1 step and self-adhesive flowable composite resin. Clinical significance: Constant research and technological advancements are taking place in dentin adhesives to improve the marginal seal. This has led to the evolution of total acid-etching dentin bonding agents termed as etch and rinse (ER)-2 steps (fifth generation dentin bonding agents) and self-etching (SE) 2 steps, and SE-1 step dentin bonding agents termed as the sixth and seventh generation bonding agents, respectively.

Effect of Different Bonding Techniques on Marginal Adaptation of Harmonize Composite Resin at Different Storage Times

Aim:

The aim of this study is to evaluate the outcome of diverse bonding methods on marginal adaptation of harmonize composite at altered times of storage.

Materials and Methods:

The study was done on 120 upper premolars with two adhesive systems (n = 60), self-etch, and total-etch type. Sixty teeth of each method were stored at three different times (n = 20) 1 day, 3, and 6 months. Class II cavities were made in all teeth restored with Harmonize composite incrementally. Then, each tooth was sectioned into two halves in buccolingual direction and observed with stereomicroscope for detecting any gaps and scanning electron microscope to assess resin-dentin junction.

Results:

Mean gap area was more in the self-etch group at the cervical and occlusal margins. Storage period of 6 months revealed significantly highest mean gap area.

Conclusions:

Total-etch system showed better marginal adaptation than the self-etch system and storage of resin in water has unfavorable marginal adaptation.

Polyphenol-enriched extract of Arrabidaea chica used as a dentin pretreatment or incorporated into a total-etching adhesive system: Effects on bonding stability and physical characterization

The aim of this paper was to evaluate the physical properties and the long-term bond strength of a 2.5% polyphenol-enriched extract of Arrabidaea chica (AC) incorporated into both the phosphoric acid and the primer of a three-step total-etch adhesive, or into an aqueous solution as a dentin pretreatment. Fifty dentin surfaces received the treatments (n = 10): CON (control) - application of the three-step adhesive system (Adper Scotchbond Multipurpose, 3M ESPE); WAT - distilled water used as a pretreatment after dentin etching and before application of the adhesive system; ACPA - AC incorporated into the phosphoric acid; ACW - dentin pre-treatment with AC incorporated into an aqueous solution after etching; ACP - AC incorporated into the primer. Microtensile bond strength tests were performed after 24 h, 6 and 12 months of storage. Slices from the resin-dentin interface were obtained for scanning electron microscopy analysis of the hybrid layer. Degree of conversion of AC incorporated into the primer was evaluated. The particle size, polydispersity index and zeta potential of all the solutions prepared by incorporating AC (phosphoric acid, primer and distilled water) were measured by dynamic light scattering, which brought about changes after incorporation. Degree of conversion of the primer was not affected after incorporating AC. ACP showed lower microtensile bond strength values than the other groups. Bond strength decreased after 6 months of storage, stabilizing at the 12-month evaluation. Therefore, use of AC incorporated into the primer led to lower bond strength values, since AC modified the physical properties (particle size, polydispersity index and zeta potential) of the primer, but did not change the degree of conversion. Application of AC as a dentin pretreatment did not affect bond strength or the micromorphological characteristics of the hybrid layer.

Nanotechnology in Dentin Disinfection: Can We Preserve the Bond?

Aims

The aim of the present study is to evaluate the effect of cavity disinfection with 2% chlorhexidine (CHX) and Ag-Au nanoparticles on microleakage and resin tag penetrability of composite restoration under in vitro conditions.

Materials and methods

Twenty-five human permanent molars extracted for therapeutic reasons were used in the study. Class V cavity of standard dimension was prepared on the buccal and lingual surfaces of the teeth. The teeth were randomly allocated into two groups based on the cavity disinfectant used; group I being 2% chlorhexidine gluconate (chlorhexidine FGM) and group II being cavity disinfectant containing Ag-Au nanoparticles (nanocare gold). In both the groups, the dentin was etched with 37% phosphoric acid and cavity disinfectants were applied following which dentine bonding agent and composite resin were applied and cured. The specimens were then viewed under stereomicroscope and scanning electron microscope for evaluation of microleakage and resin tag formation, respectively.

Results

The results were statistically analyzed using independent ‘t’ test. No significant difference was seen between the two groups with respect to the microleakage and resin tag penetration values (p >0.05).

Conclusion

Cavity disinfectant containing Ag-Au nanoparticles had no effect on the sealing ability and resin tag penetrability of composite resin in permanent molars when compared with 2% CHX.

Clinical significance

Use of Cavity disinfectant containing Ag-Au nanoparticles with etch and rinse system can be preferred as it satisfies the ideal property of a cavity disinfectant which includes excellent antimicrobial action and non-detrimental effect on the sealing ability and resin tag penetrability.

How to cite this article

Ramasetty PA, Tripathi AP, Sugandhan S, Naik SV, Deepak BM. Nanotechnology in Dentin Disinfection: Can We Preserve the Bond? Int J Clin Pediatr Dent, 2018;11(6):468-473

Nanotechnology in Dentin Disinfection: Can We Preserve the Bond?

Aims

The aim of this study is to evaluate the effect of cavity disinfection with 2% chlorhexidine (CHX) and Ag–Au nanoparticles on microleakage and resin tag penetrability of composite restoration under in vitro conditions.

Materials and methods

Twenty-five human permanent molars extracted for therapeutic reasons were used in the study. Class V cavity of standard dimension was prepared on the buccal and lingual surfaces of the teeth. The teeth were randomly allocated into two groups based on the cavity disinfectant used: group I being 2% CHX gluconate (chlorhexidina Friedrich and Bianca Mittelstadt (FGM)) and group II being cavity disinfectant containing Ag–Au nanoparticles (nanocare gold). In both the groups, the dentin was etched with 37% phosphoric acid and cavity disinfectants were applied following which dentine bonding agent and composite resin were applied and cured. The specimens were then viewed under a stereomicroscope and a scanning electron microscope for microleakage and resin tag formation, respectively.

Results

The results were statistically analyzed using an independent “t” test. No significant difference was seen between the two groups with respect to both microleakage and resin tag penetration values (p > 0.05).

Conclusion

The cavity disinfectant containing Ag–Au nanoparticles did not affect the sealing ability and resin tag penetrability of composite resin in permanent molars when compared with 2% CHX.

How to cite this article

Attiguppe P, Tripathi AP, et al. Nanotechnology in Dentin Disinfection: Can We Preserve the Bond? Int J Clin Pediatr Dent 2019;12(1):42–46.

Does the use of a novel self-adhesive flowable composite reduce nanoleakage?

Objective

The aim of the study reported here was to evaluate the performance of a self-adhesive flowable composite and two self-etching adhesive systems, when subjected to cyclic loading, in preventing the nanoleakage of Class V restorations.

Methods

Wedge-shape Class V cavities were prepared (4×2×2 mm [length × width × depth]) on the buccal surfaces of 90 sound human premolars. Cavities were divided randomly into three groups (n=30) according to the used adhesive (Xeno^® V [self-etching adhesive system]) and BOND-1^® SF (solvent-free self-etching adhesive system) in conjunction with Artiste^® Nano Composite resin, and Fusio™ Liquid Dentin (self-adhesive flowable composite), consecutively. Each group was further divided into three subgroups (n=10): (A) control, (B) subjected to occlusal cyclic loading (90N for 5,000 cycles), and (C) subjected to occlusal cyclic loading (90N for 10,000 cycles). Teeth then were coated with nail polish up to 1 mm from the interface, immersed in 50% silver nitrate solution for 24 hours and tested for nanoleakage using the environmental scanning electron microscopy and energy dispersive analysis X-ray analysis. Data were statistically analyzed using two-way analysis of variance and Tukey’s post hoc tests (P≤0.05).

Results

The Fusio Liquid Dentin group showed statistically significant lower percentages of silver penetration (0.55 μ) compared with the BOND-1 SF (3.45 μ) and Xeno V (3.82 μ) groups, which were not statistically different from each other, as they both showed higher silver penetration.

Conclusion

Under the test conditions, the self-adhesive flowable composite provided better sealing ability. Aging of the two tested adhesive systems, as a function of cyclic loading, increased nanoleakage.

Microleakage of class V resin composites using various self-etching adhesives: an in vitro study

BACKGROUND AND AIMS

Microleakage has been identified as a significant problem with composite restorations because of interfacial gap formation which can result in tooth discoloration, recurrent caries, possible pulpal involvement and restoration replacement. Aim of this study is to evaluate the microleakage of self-etch adhesive system at the coronal and apical margins of class V resin composite restorations under stereomicroscope at 20× magnification.

MATERIALS AND METHODS

Class V cavities were prepared on the facial surfaces of 48 human premolars with coronal margins located in enamel and apical margins located in dentin. Teeth were divided into four groups: Group one-Xeno V; group two- G-Bond; group three-Clearfil S(3) Bond; group four-control. After application of bonding agent and restoration, the teeth were subjected to thermocycling. The teeth were then immersed in 1% aqueous solution of methylene blue dye for 24 hours and sectioned to allow the assessment of microleakage under microscope.

RESULTS

Coronal and apical margins were scored separately using a 0-3 ordinal ranking system and the recorded values were statistically analyzed using Kruskal-Wallis, Mann- Whitney U-test and Wilcoxon signed rank test. Statistical analysis showed that there was less microleakage in Xeno V at coronal region and Clearfil S(3) Bond in apical region, overall Clearfil S(3) Bond showed less marginal permeability in both coronal and apical regions.

CONCLUSION

Specimens restored with the Xeno V and Clearfil S(3) Bond adhesive systems revealed reduced leakage at the coronal margin. At the apical margin, Xeno V showed greater leakage than the other groups, except the control.

CLINICAL SIGNIFICANCE

In class V restorations restored with composite resin, the choice of material affects the microleakage and retention of the restoration. This study theorizes that the self-etch adhesives show less microleakage in the coronal area than the apical margin.

Shear bond strengths and morphological evaluation of filled and unfilled adhesive interfaces to enamel and dentine

In this laboratory study shear bond strengths of three filled and one unfilled adhesive systems to enamel and dentine were compared. Forty-eight extracted intact noncarious human mandibular molars were randomly assigned to two groups of 24 one for bonding to enamel and the other for bonding to dentine. Buccal and lingual surfaces of each tooth were randomly assigned for application of each one of filled (Prime & Bond NT (PBNT), Optibond Solo Plus (OBSP), and Clearfil SE Bond (CSEB)) and unfilled (Single Bond (SB)) adhesive systems (n = 12). A universal resin composite was placed into the translucent plastic cylinders (3 mm in diameter and 2 mm in length) and seated against the enamel and dentine surfaces and polymerized for 40 seconds. Shear bond strength was determined using a universal testing machine, and the results were statistically analyzed using two-way ANOVA, one-way ANOVA, t-test, and Tukey HSD post hoc test with a 5% level of significance.There were no statistically significant differences in bond strength between the adhesive systems in enamel, but CSEB and SB exhibited significantly higher and lower bond strength to dentine, respectively, than the other tested adhesive systems while there were no statistically significant differences between PBNT and OBSP.

Morphological evaluation of new total etching and self etching adhesive system interfaces with dentin

Aim:

The purpose of this study is to evaluate the resin-dentin interface, quality of the hybrid layer of total-etching and self-etching adhesive systems under scanning electron microscopy (SEM).

Materials and Methods:

Class V cavities were prepared in 40 extracted human molars. In Group I XP bond (Dentsply), in Group II Adper Single Bond II (3M ESPE), in Group III Adper Easy One (3M ESPE), and in Group IV Xeno V (Dentsply) were applied. Teeth were restored with resin composite, subjected to thermocycling, and sectioned in Buccolingual plane. The samples were demineralized using 6N HCl, for 30 sec, and deproteinized with 2.5% NaOCl for 10 min, gold sputtered, and viewed using a scanning electron microscope.

Results:

Among the total-etch systems used, the XP Bond showed a clear, thick hybrid layer, with long resin tags and few voids. Among the self-etch adhesive systems, the Xeno V did not show a clearly recognizable hybrid layer, but there were no voids and continuous adaptation was seen with the dentin.

Conclusion:

The adaptation of self-etch adhesives to the resin-dentin interface was good without voids or separation of phases; showing a thin, continuous hybrid layer.

In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study

Aim:

To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin–dentin interfacial ultrastructure under scanning electron microscope (SEM).

Materials and Methods:

100 extracted human premolars were divided into two groups for different adhesives (Clearfil S³ and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin–dentin interface.

Results:

At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin–dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied.

Conclusions:

In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage.

Comparative evaluation of microleakage of fifth, sixth, and seventh generation dentin bonding agents: An in vitro study

Objectives:

The purpose of this study was to determine the microleakage in the 5^th and 6^th generation bonding agents with that compared with the newly introduced 7^th generation bonding agents using three bonding agents.

Materials and Methods:

A total of 50 recently extracted human upper premolars were subjected to the study. Class V cavity preparations were prepared on the buccal and lingual surfaces of the extracted premolars with occlusal margins in the enamel and gingival margins in the cementum/dentin. The teeth were divided into five groups of 10 teeth each and 20 cavity preparations per group. In the experimental groups, cavities were treated with Single-Bond, Adper Prompt, i-Bond, Clearfil S3, and G-Bond as the dentin bonding agents. After the application of the dentin bonding agents, the cavity preparations were restored with resin composite (Clearfil APX). The specimens were thermocycled, stained with methylene blue dye, and sectioned to evaluate the dye penetration. Data were analyzed using the one-way ANOVA test (Kruskal–Wallis) and Dunn’s procedure for pairwise comparison of the data.

Results:

This study showed that at the coronal margin and the apical margins, the preparations treated with Clearfil S3 showed significantly less leakage than the other groups. Enamel margins provided better marginal sealing than dentin/ cementum margins.

Interpretation and Conclusion:

The study demonstrated that Clearfil S3 bond had a better sealing ability at both coronal (enamel) and apical (dentin/cementum) margins compared with the other dentin bonding agents used.

Effect of dentine smear layer on the performance of self-etching adhesive systems: A micro-tensile bond strength study

This study aimed to evaluate the effect of the smear layer on the micro-tensile bond strength when two self-etching adhesives were used with different techniques. Flat dentine surfaces were prepared using either medium grit diamond burs or tungsten carbide burs. Ten specimens from each prepared surfaces were subjected for smear layer evaluation under SEM. Forty specimens from each of the prepared surfaces were further divided into two groups, bonded with either Clearfil SE Bond (SE) or Clearfil S(3) Bond (S3) using one of four applications (as manufacturer's instructions, agitation, reapplication, and increased application time), restored with composites and subjected to a micro-tensile bond strength test. Smear layers created with diamond burs were thicker than those created with tungsten carbide burs. Surfaces prepared with tungsten carbide burs produced a higher bond strength than those prepared with diamond burs and the same type of adhesive resin. SE demonstrated a higher bond strength than S3 for all surfaces. S3 applied with the agitation technique demonstrated a higher bond strength to dentine prepared with tungsten carbide and diamond burs than that applied with other techniques. SE applied with increased time on dentine treated with carbide burs produced the highest bond strength. In conclusion, a thick smear layer decreased bond strength to dentine, and this might be improved by modification of application technique.

Enzymatic biodegradation of HEMA/bisGMA adhesives formulated with different water content

Dentin adhesives may undergo phase separation when bonding to wet demineralized dentin. We hypothesized that adhesives exhibiting phase separation will experience enhanced biodegradation of methacrylate ester groups. The objective of this project was to study the effect of enzyme-exposure on the release of methacrylic acid (MAA) and 2-hydroxyethyl methacrylate (HEMA) from adhesives formulated under conditions simulating wet bonding. HEMA/bisGMA(2,2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl] propane), 45/55 w/w ratio, was formulated with different water content: 0 Wt % (A00), 8 wt % (A08), and 16 wt % (A16). After a three day prewash, adhesive discs were incubated with/without porcine liver esterase (PLE) in phosphate buffer (PB, pH 7.4) at 37 degrees C for 8 days. Supernatants were collected daily and analyzed for MAA and HEMA by HPLC. For all formulations, daily MAA release in the presence of PLE was increased compared to MAA release in PB. HEMA release in the presence of PLE was not detected while HEMA release was consistently measured in PB. A08 and A16 released significantly larger amounts of HEMA compared to A00. Analysis of the cumulative release of analytes showed that the leachables in PLE was significantly increased (p < 0.05) as compared with that released in PB indicating that MAA release was not only formed from unreacted monomers but from pendant groups in the polymer network. However, the levels of analytes HEMA in PB or MAA in PLE were increased in A08 and A16 as compared with A00, which suggests that there could be a greater loss of material in HEMA/bisGMA adhesives that experience phase separation under wet bonding conditions.

Effect of Surface Treatments and Different Adhesives on the Hybrid Layer Thickness of Non-carious Cervical Lesions

The quality of the hybrid layer created in non-carious cervical sclerotic lesions may determine the longevity of cervical composite restorations.