Compromised Bond Strength Research Articles

Comparative Evaluation of Various Antioxidants on the Shear Bond Strength of Composite Resin to Bleached Enamel - An In Vitro Study.

To evaluate and compare the effect of various antioxidants on the shear bond strength of composite resin to bleached enamel. Labial enamel surfaces of 90 extracted human maxillary central incisors were randomly divided into five groups based on the antioxidant used as follows: Group I ( n = 20): Bleaching with 40% hydrogen peroxide gel for 10 min, without the use of an antioxidant; Group II ( n = 20): Bleaching followed by the use of 10% sodium ascorbate solution; Group III ( n = 20): Bleaching followed by the use of 5% grape seed extract solution; Group IV ( n =20): Bleaching followed by the use of 5% pine bark extract solution; and Group V ( n =20): Control group in which no bleaching was done. Groups I-IV were further subdivided into two subgroups of 10 teeth each, whether the antioxidant application and composite build-up was done immediately (subgroup A) or after 2 weeks of postbleaching (subgroup B). Shear bond strength of the specimens was tested under a universal testing machine. One-way analysis of variance followed by Mann-Tukey posthoc multiple comparison test was used to analyse the data. The level of significance was established at P < 0.05. Within the limitations of this study, it was observed that the use of antioxidants effectively reversed the compromised bond strength of bleached enamel. Among the antioxidants, 5% pine bark extract application after bleaching showed better bond strength.

Shear bond strength of orthodontic brackets bonded with primer-incorporated orthodontic adhesives and unpolymerized 3-dimensional printing materials on 3-dimensional-printed crowns

The use of 3-dimensional (3D) printing techniques in fabricating crowns has increased the demand for bracket bonding onto these surfaces. The objective was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded onto 3D-printed crowns using primer-incorporated orthodontic adhesives and 3D printing materials as orthodontic adhesives. A total of 160 crowns were printed with two 3D printing materials, DentaTOOTH (Asiga, Sydney, Australia) (group A) and NextDent C&B Micro Filled Hybrid (3D Systems, Soesterberg, Netherlands) (group N). Each group was randomly divided into 4 adhesive subgroups (n= 20): Transbond XT (for groups A [ATX] and N [NTX]; 3M Unitek, Monrovia, Calif), Ortho Connect (for groups A [AOC] and N [NOC]; GC Corporation., Tokyo, Japan), Orthomite LC (for groups A [AOM] and N [NOM]; Sun Medical, Co Ltd, Moriyama, Shiga, Japan), and unpolymerized liquid state of 3D printing resin (for groups A [AA] and N [NN]). SBS was measured with a universal testing machine at a crosshead speed of 0.5 mm/min. The adhesive remnant index and the mode of failure were analyzed under the microscope. Statistical analysis was performed at a significance level of α= 0.05. When used as adhesives (AA and NN), 3D printing materials showed no statistically significant difference in SBS compared with Transbond XT (ATX and NTX, respectively). In group N, NN showed a significantly higher SBS than primer-incorporated orthodontic adhesives (NOC and NOM; P<0.001). Adhesive failures were only observed in primer-incorporated orthodontic adhesives (AOC, NOC, AOM, and NOM). Primer-incorporated orthodontic adhesives, as well as unpolymerized 3D printing materials employed as orthodontic adhesives on 3D-printed crowns, exhibited comparable bonding strength to Transbond XT without surface modification. Despite variations in adhesive-related factors, all measurements stayed within clinically acceptable ranges, highlighting the potential of these materials for orthodontic bonding on 3D-printed crowns, simplifying clinical procedures without compromising bond strength.

Effect of Sodium Ascorbate, Grape Seed Extract, and Aloe Vera Application after In-Office Bleaching on the Bond Strength of Enamel: A 3-Year Evaluation

Introduction. Dental bleaching is the first choice to improve smile esthetics, but, in some cases, it needs to be associated with resin composite restoration to obtain a satisfactory result. Unfortunately, the bonding of resin-based materials can be impaired due to residual oxygen molecules, which can decrease the durability of the restoration. Objectives. To evaluate the effect of the antioxidant application on the bond strength of bleached enamel after 24 hr and 3 years of water storage. Methods. In total, 84 bovine teeth were used in this study. Of these, 77 were bleached with 35% hydrogen peroxide in a single session for three cycles of 15 min. Then, the specimens were divided into groups (n = 7 each): control (without bleaching), without antioxidant (WA) use; application of 10% sodium ascorbate (SA) gel, grape seed (GS) extract, and aloe vera (AV). The restorative procedure was performed immediately after bleaching, 7 and 14 days after bleaching. Specimens were sectioned and evaluated using microtensile bond strength (μTBS). Half of the resin-enamel sticks were tested after 24 hr, and the remaining half after 3 years of water storage. µTBS data were analyzed using a three-way analysis of variance, Tukey’s test, and Dunnett’s test. Results. The lowest µTBS values were observed when the restoration was performed immediately after bleaching in the AV, GS, and WA groups when compared with the SA group ( p &lt; 0.005 ). However, no significant differences were observed among all groups after 3 years of water storage ( p &lt; 0.001 ). Conclusions. SA at 10% was the most effective antioxidant agent for improving the immediate bond strength. However, independent of the antioxidant agent used, the bond strength values were maintained or recovered after 3 years of water storage. SA at 10% could be used to avoid delayed bonding procedures after in-office whitening without compromising bond strength over time. Clinical Significance. The use of antioxidants after dental bleaching can be effective in improving the bonding durability of the adhesive restorations.

Does the Elapsed Time from Bleaching and the Use of Sodium Ascorbate Influence the Bond Strength of Resin Cement to Bleached Enamel?

The objective of this study was to evaluate different delaying times after bleaching and the use of different sodium ascorbate (SA) concentrations (10% and 35%) in the bond strength of adhesive cementation to enamel. This study used 54 sound bovine incisors, which were randomly assigned to the following groups: G1 (unbleached/control+ adhesive cementation (AC)); G2 (bleached + AC after 7 days); G3 (bleached + 10% SA + AC after 24 h); G4 (bleached + 10% SA + AC after 7 days); G5 (bleached + 35% SA + AC after 24 h); and G6 (bleached + 35% SA + AC after 7 days). After bleaching, G3, G4, G5, and G6 received an application of SA before the cylinders build up with RelyX Veneer cement. The samples were subjected to microshear test, and the results were analyzed by two-way ANOVA with Tukey's post hoc test. Group one presented the highest mean bond strength (19.1 MPa) and G3 the lowest (16.96 MPa). There was no statistical difference between the groups tested (p ˃ 0.05). The fracture pattern observed was predominantly mixed. The adhesive cementation may be performed 24 h after bleaching when SA (10% or 35%) is used or after 7 days, without compromising bond strength.

Comparative Evaluation of Effect of Different Antioxidants on Shear Bond Strength of Composites on Bleached Enamel: An In Vitro Study.

To evaluate the effect of antioxidants on the shear bond strength of composite resin to bleached enamel. A total of 120 extracted permanent anterior teeth were split into four major groups, one among them being a control group. Group I (bleaching + without antioxidant), group II (bleaching + 10% sodium ascorbate), group III (bleaching + 5% grape seed extract), and group IV (bleaching + 5% pine bark extract). All of the groups were bleached using a gel containing 35% carbamide peroxide, and then they were divided into two subgroups depending on when the bonding operation was to be completed-subgroup A was done in 24 hours, while subgroup B took 3 weeks. The universal testing machine was used to measure the shear bond strength. Subgroup IA showed poor shear bond strength than other groups, there was no statistically significant difference between subgroup IB, IIA, and IVA. Subgroup IIIA showed the highest shear bond strength than the remaining groups. Between subgroups IIA and IIB, IIIA and IIIB, and IVA and IVB there was no statistically significant difference. This shows that delaying the bonding procedure for 3 weeks shows similar shear bond strength when compared to groups that were immediately bonded after antioxidant applying groups. All the antioxidants' immediate application could reverse compromised bond strength. Among them, 5% grape seed extract shows the highest increase in shear bond strength. Maddula DC, Vasepalli M, Martha S, et al. Comparative Evaluation of Effect of Different Antioxidants on Shear Bond Strength of Composites on Bleached Enamel: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(1):87-92.

Effect of natural antioxidants on bond strength recovery of resin-modified glass ionomers to the NaOCl-affected pulp chamber dentin.

This study evaluated the effect of two natural antioxidants on the compromised bond strength of a resin-modified glass ionomer (RMGI) to the sodium hypochlorite (NaOCl)-affected pulp chamber dentin. Forty-two sound third molars were split into halves. The exposed pulp chamber dentin was ground to provide the flat dentin surfaces and divided into seven groups (n = 12), according to the solutions used for immersion: (1) Control, distilled water; (2) NaOCl, 5.25% NaOCl for 20 min;(3) NaOCl/Ethylenediaminetetraacetic acid (EDTA); 5.25% NaOCl for 20 min + 17% EDTA for 1 min;(4) NaOCl/TA, 5.25% NaOCl + 10% tanic acid (TA) for 5 min;(5) NaOCl/EDTA/TA, 5.25% NaOCl + 17% EDTA + 10% TA for 5 min;(6) NaOCl/PA, 5.25% NaOCl+ 10% proanthocyanidin for 5 min;and (7) NaOCl/EDTA/PA, 5.25% NaOCl+ 17% EDTA + 10% PA for 5 min. The RMGI was bonded on the treated dentin using a Tygon tube. After 24 h of storage, microshear bond strength (µSBS) was tested. Data in MPa were submitted to one-way analysis of variance and Tamhane test. NaOCl significantly decreased the µSBS; NaOCl/EDTA and NaOCl/TA significantly increased the µSBS, higher than the control group (p < .05);and in the NaOCl/EDTA/TA group, the increased bond strength was at the level of the control group (p > .05). NaOCl/PA and NaOCl/EDTA/PA and NaOCl groups had comparable µSBS. TA could be suggested to provide effective bonding of RMGI and immediate sealing of the pulp chamber dentin after NaOCl irrigation.

Impact of Dentine Pretreatment with Matrix Metalloproteinase Inhibitors on Bond Strength of Coronal Composite Restorations: A Systematic Review and Meta-analysis of In Vitro Studies.

Matrix metalloproteinase (MMP) enzymes participate in collagen matrix degradation, including in dentine, potentially compromising bond strength. Therefore, MMP inhibitors have been hypothesized to improve restoration bond strength and stability. This systematic review aimed to evaluate the influence of different MMP inhibitors applied as dentine surface pretreatments on the immediate (24 hours) and longer term (months) bond strength of direct coronal composite restorations. This systematic literature review followed the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statement. A systematic literature search of three databases (Ovid MEDLINE, Ovid Embase, and Google Scholar) was conducted independently by two reviewers from inception to April 2022. An adapted quality assessment tool was independently applied by two reviewers for risk of bias assessment. RevMan v5.4 software was used for meta-analyses. A randomeffectsmodel was used to generatemean differences with 95% confidence intervals for treatment and control comparisons. The Q-test and I2-test were used to test for heterogeneity. The proportion of total variance across studies attributable to heterogeneity rather than chance was calculated. Overall effects were tested using the Z-test, while subgroup differences were tested using Chi-squared tests. Of 934 studies, 64 studies were included in the systematic review and 42 in the meta-analysis. Thirty-one MMP inhibitors were reported, three of which were included in the meta-analysis: 2% chlorhexidine (CHX), 0.3M carbodiimide (EDC), and 0.1% riboflavin (RIBO). Pretreatment with 2% CHX for 30 and 60 seconds did not significantly improve bond strength compared with controls either immediately or after long-termageing. However, pretreatment with 0.3MEDC and 0.1% RIBO (but not CHX) significantly improved bond strength compared with control groups both immediately and over time. Most studies showed a medium risk of bias. These in vitro findings pave the way for rationale clinical trialing of dentine surface pretreatment with MMP inhibitors to improve clinical outcomes.

Evidence of improved bond strength of resin-based sealer with the use of natural antioxidants on hypochlorite treated dentin: an in vitro study.

AimTo evaluate the effect of natural antioxidants as final irrigants on the push-out bond strength of epoxy resin-based sealer to the hypochlorite treated dentin.MethodsEighty single-rooted human mandibular incisors were prepared using ProTaper Gold (Dentsply, TN, USA) and an irrigation protocol including 3% NaOCl, followed by ethylenediaminetetraacetic acid (EDTA), and 3% NaOCl. The groups (n =20) were divided according to the final irrigant used: Group 1: None (Control); Group 2: 5% sodium ascorbate, Group 3: 5% grape seed extract (GSE); and Group 4: 5% pine bark extract. The obturation of root canals was performed using gutta-percha and AH Plus (Dentsply DeTrey, Germany). Bond strength was evaluated using the push-out test under the universal testing machine at a crosshead speed of 0.5 mm/min, and statistical analyses were performed using one-way ANOVA. The p-value significance was evaluated by Tukey’s post hoc test (p<0.01).ResultsMean push-out bond strength values were compared in all the groups, and there was a statistically significant improvement in the experimental final irrigating groups. 5% pine bark extract had improved bond strength than the other groups, and the least bond strength was observed in the control group.ConclusionThe irrigation protocols and naturally derived antioxidants affected the resin-based sealer’s bond strength to root dentin. It was observed that the use of antioxidants effectively reversed the compromised bond strength of resin-based sealers to root dentin. 5% pine bark extract application showed better bond strength.

High-Intensity Light-Emitting Diode and Reduced Curing Times—An In Vitro Study

Objective: To evaluate and compare the effect of high-intensity light-emitting diode (LED) light-curing unit at different curing times on the shear bond strength (SBS), surface enamel loss, and degree of polymerization of a light-cure and dual-cure adhesive system. Materials and Methods: One hundred and twenty extracted human premolar teeth were divided into 2 groups— group 1 (light cure) and group 2 (dual cure), depending on the adhesive system used. These groups were further subdivided into 3 subgroups with 20 teeth each, depending on the duration of curing. A high-intensity LED curing unit was used to bond metal brackets onto the teeth. The samples were tested on a universal testing machine to measure the SBS. The samples were then observed under a simple microscope and modified adhesive remnant index scores were assigned. The bracket bases were mapped with energy-dispersive X-ray spectrometry to evaluate the amount of enamel present. Cured adhesive was scraped and was subjected to Fourier-Transform Infrared Spectroscopy to assess the degree of cure (%DC). Results: An increase in curing durations increased mean SBS values, %DC, and calcium-phosphorous ratios (Ca:P). Similarly, these parameters were higher for dual-cure subgroups when compared to light-cure subgroups. Conclusion: High-intensity LEDs can be used successfully for bonding orthodontic brackets with reduced curing duration. These LEDs help to reduce chairside time and can minimize damage to enamel without compromising bond strength.

Graphene functionalized with nanosilver particle‐modified methacrylate‐based bonding agent improves antimicrobial capacity and mechanical strength at tooth orthodontic bracket interface

AbstractThe purpose of this study was to formulate and characterize functionalized graphene nanoplatelets (GNP) with silver nanoparticles (AgNPs) and evaluate the antimicrobial and mechanical properties of GNP‐Ag‐modified adhesives bonded to orthodontic brackets. The morphology and physiochemical properties of nanoparticles were studied. The functionalized nanoparticles were incorporated at 0.25 and 0.5 wt% into experimental orthodontic adhesives (Transbond XT) and characterized for their biological, antimicrobial capacity, degree of conversion (DC), shear bond strength (SBS), and adhesive remnant index (ARI). Among the experimental groups, the specimen treated with 0.25 wt% modified experimental adhesive had the highest mean DC score (40.8 ± 6.5), shear bond strength (9.8 ± 1.8), lowest mean adhesive remnant index scores (1.35 ± 0.78), and the lowest cytotoxicity effect after 72 h (p &lt; 0.001). However, 0.5 wt% GNP‐Ag modified experimental adhesive specimens showed a greater relative antibiofilm viability against S. mutans after 24 h and 30 days in comparison to 0.25 wt%. Our study found that 0.25 wt% revealed substantial increase in antibacterial properties and therefore could be used for bonding orthodontic brackets to the enamel surface without compromising bond strength.

Influence of different antioxidant agents on the microtensile bond strength of restored teeth after bleaching

Introduction Due to an increase in patient awareness and search for aesthetic treatments, dental bleaching is a frequent and safe procedure in clinical practice for the removal of stains [1]. Bleaching agents are known to adversely affect the bond strength between resin composite and tooth surface, when adhesive procedures are performed immediately after tooth bleaching [2]. The reduction in bond strength is related to the presence of residual oxygen, a sub product of hydrogen peroxide that remains on the tooth surface and which may interfere with infiltration of the resin in the dentine tubules and inhibit the polymerisation of resin monomers [3]. Antioxidant agents like sodium ascorbate, grape seed extract and green tea may be used as an alternative to delay the restorative procedure due to their potential as reversers of these adverse effects [2]. This study aims to assess the influence of different antioxidant agents on the bond strength of restored bleached teeth. Materials and methods The present study was approved by the Ethics Committee of Instituto Universitário Egas Moniz. Fifteen human permanent molars were sectioned into identical halves that were randomly distributed between five groups (n = 6): unbleached control group (CG), bleaching + resin composite bonded immediately (G1), bleaching + sodium ascorbate (G2), bleaching + grape seed extract (G3) and bleaching + green tea (G4). G1, G2, G3 and G4 were bleached for 4 h/day for a 7-day period. After bleaching, G1 samples were immediately restored with an adhesive system and a resin composite, in G2 samples a 10% sodium ascorbate gel was applied, in G3 a 5% grape seed extract and in G4 a 5% green tea, all applied for 15 min. After these antioxidants, G2, G3 and G4 were immediately restored. After 24 h, samples were sectioned in order to obtain 1.0 (± 0.3) mm2 microspecimens. The microspecimens were tested in a universal testing machine at a speed of 0.5 mm/min. Data were analysed by using a two-way ANOVA, at a significance level of 5%. Results G1 group (bleaching only) recorded the lowest mean bond strength value (9.5 (± 1.2) MPa) and it was significantly lower than the control group (CG) (19.3 (± 2.7) MPa) (p = .001). Groups in which sodium ascorbate (G2) (19.2 (± 1.3) MPa), grape seed extract (G3) (16.5 (± 0.8) MPa) and green tea (G4) (16.7 (± 2.0) MPa) were applied presented significantly higher bond strength values when compared to bleaching only (G1) (p < .001). When comparing the antioxidant agents, G2 (10% sodium ascorbate) exhibited significantly higher mean bond strength values when compared to G3 (5% grape seed extract) (p = .016). Discussion and conclusions Treatment of the enamel surface with antioxidant agents such as sodium ascorbate, grape seed extract and green tea following the bleaching procedure and immediately before the restorative procedure can reverse the compromised bond strength. These alternative strategies are effective and may be used instead of delaying the procedure.

Comparative evaluation of 6% cranberry, 10% green tea, 50% aloe vera and 10% sodium ascorbate on reversing the immediate bond strength of bleached enamel: In vitro study

ObjectivesThe present study aimed to assess antioxidant activity of herbal antioxidants namely 6% cranberry extract, 10% green tea, 50% aloe vera and 10% sodium ascorbate and their effect on reversal of bond strength in bleached enamel. Materials and methodFrom one hundred and twenty extracted maxillary central incisors enamel blocks of 5 ​× ​5 ​mm were prepared and arbitrarily divided into six experimental groups (n ​= ​20): Group A: no bleaching, Group B: only bleaching protocol, Group C – bleaching ​+ ​6% cranberry extract solution, Group D – bleaching +10% Green Tea extract, Group E − bleaching ​+ ​50% aloe vera extract, Group F – bleaching ​+ ​10% Sodium Ascorbate. After bleaching antioxidants were applied for 10 ​min and were subjected to bonding procedures. The specimens were sectioned into 120 small strips of size (1 ​× ​1 ​× ​8 ​mm). Sixty sticks were analyzed to micro tensile bond strength using Universal testing machine and fractured segment were observed for failure modes (Adhesive, Cohesive and Mixed) under stereomicroscope. Remaining 60 sticks were observed for interface gap between tooth and composite resin under SEM. The %AA (antioxidant activity) was assessed with spectrophotometric analysis. ResultsData was statistically analyzed using ANOVA and Post Hoc Tukey’s test. Group A (91.68 ​± ​2.24 Mpa) showed higher mean micro tensile bond strength versus group D (82.14 ​± ​1.45 Mpa), followed by group E (75.26 ​± ​1.92Mpa), group F (63.89 ​± ​1.95Mpa), group C (57.58 ​± ​1.96 Mpa) and least in group B (31.5 ​± ​1.27 Mpa). The %failure mode inferred maximum adhesive mode of failure (86.25%). ConclusionAll the four antioxidants were able to reverse the compromised bond strength comparatively after bleaching maximum being green tea followed by aloe vera, sodium ascorbate, and minimum in cranberry. Clinically significance-Easily available, biocompatible, cost effectual, and potent herbal antioxidants could be used considerably for immediate esthetic cases where time is a restricting factor.

Effect of different bleaching treatment protocols on shear bond strength of bonded orthodontic brackets with no-primer adhesive resin

BACKGROUNDS:Bleaching procedure can be companied before, during, or after orthodontic treatments. However, the risk of compromised bond strength of brackets to bleached enamels is in debate. This study tried to evaluate the shear bond strength (SBS) of bonded metal brackets to the previously bleached enamels.MATERIALS AND METHODS:In this in vitro study, 60 extracted, sound, human premolars were mounted vertically in cylindrical molds. The samples were randomly divided into four groups (n = 15): Control (C); at-home bleached by 20% carbamide peroxide (HB); in-office bleached by 45% carbamide peroxide (OB); and in-office bleached by 40% hydrogen peroxide activated with diode laser (L-OB). Sixty stainless steel brackets were bonded by no-primer adhesive resin (OrthoCem). Then SBS of bonded brackets was measured after 5000 thermal cycles at 5°C and 55°C. Finally, the collected data were analyzed by one-way ANOVA, and Tukey HSD tests by using SPPS software at a significant level of 0.05 (α = 0.05).RESULTS:Group C showed significantly higher SBS values (all P < 0.001); however, there were no significant differences in SBS compared to other tests' groups with each other (all P > 0.05).CONCLUSION:The SBS of bonded orthodontic brackets were compromised after bleaching with 20% and 40% of carbamide peroxide. Diode laser activation may not eliminate the negative effect of bleaching agents on SBS of bonded orthodontic brackets, neither.

Evaluation and comparison of the effect of 10% sodium ascorbate and propolis solution on the microtensile bond strength and resin tag penetration depth of composite after using 35% carbamide peroxide bleaching agent – An in vitro study

Aim: The aim of this study was to evaluate and compare the effect of 10% sodium ascorbate and propolis solution on the microtensile bond strength (MTBS) and resin tag penetration depth of composite after using 35% carbamide peroxide bleaching agent.Materials and Method: Sixty extracted human premolars were divided into five groups with 12 samples in each. Group I samples did not receive bleaching treatment and served as control. Group II samples were bonded with composite 2 weeks later, while those in Group III were bonded immediately after bleaching. The samples in Group IV and Group V were treated with antioxidants 10% SA and propolis solution at the rate of 1ml/min for 10 min, respectively, before composite bonding. The samples were then sectioned mesiodistally into two halves. One half was subjected to MTBS testing using a Universal Testing Machine. The other half was decalcified, sectioned, stained, and viewed under an optical light microscope to assess the resin tag penetration. The results obtained were statistically analyzed using a one-way analysis of variance followed by Post hoc test.Results: Group III showed significantly lower MTBS and resin tag penetration depth of composite compared to all other groups. Group V (propolis group) showed statistical significance with all groups except Group IV (SA group).Conclusion: Treatment with antioxidant propolis solution immediately following the bleaching will help to reverse the compromised bond strength which is comparable with sodium ascorbate.

Evaluation of Antioxidant Property of Amla on Bond Strength and Color Stability of Power Bleached Teeth: An In vitro Study.

Introduction:Objective: To assess the antioxidant property of 10% amla extract in reversing the compromised bond strength and to assess the antioxidant property of 10% amla extract and Elsenz on the color stability of power bleached teeth.Materials and Methods:Ninty extracted single-rooted maxillary anterior were collected and divided as follows: The labial surfaces of 30 samples were subjected to power bleaching after which the samples were divided into three groups– Group I (control), Group II (antioxidant amla), and Group III (Elsenz) with n = 10 in each which were then stained with a coffee solution for 10 mins. The color difference was recorded with a colorimeter at baseline, after bleaching, after 7, and after 15 days of staining. sixty specimens were randomly divided into six groups (n = 10) as following: Group I (immediate bonding); Group II (bleaching + immediate bonding); Group III (bleaching + antioxidant and immediate bonding); Group IV (bleaching + 1 week storage + antioxidant + bonding); Group V (bleaching + 2 week storage + antioxidant + bonding); Group VI (bleaching + 2 week storage + bonding). All the specimens were tested for shear bond strength in universal testing machine. Statistical analysis was performed using ANOVA and Scheffe's post hoc test.Results: Significantly higher staining was observed in Group II (amla) and least with Elsenz pasteThe highest mean shear bond strength was found in Group I followed by Group V. Conclusion:Elsenz showed the least staining followed by artificial saliva. 10% Amla extract neither was effective in preventing staining of power bleached enamel nor in restoring the poor bond strength of power bleached enamel.

Microtensile bond strength of TTEMA/TEGDMA remineralizing adhesive to early carious enamel lesions

Objectives: Resin adhesive could be used as a carrier of nano-hyrdoxy apatite particles added to treat early enamel caries. The aim of this study was to evaluate microtensile bond strength of a remineralizing enamel infiltrant to early carious enamel lesion. Methods: An artificial caries model was used to induce early partially-cavitated enamel caries-like lesion in maxillay centrals. Nano hydroxyapatite particles (nHA) were applied in two forms to a low shrinkage low viscosity resin adhesive: particles were directly added to resin adhesive or silanated before addition. Unmodified ad-hesive was used as control. Micro-tensile bond strength (MTBS) was performed to evaluate bond strength to demineralized enamel after application of the remineralizing resin adhesive (n=20, α=0.05). Scanning electron microscopy (SEM) was performed to assess mode of failure and to study infiltrant-enamel interface. Results: Direct addition of nano-particles resulted in significant reduction (F=32, P<0.001) in MTBS (19 MPa ± 3.8) compared to addition of silanated particles (24 MPa ± 3.2) which presented comparable values to the unmodified enamel infiltrant (26 MPa ± 4.1). SEM image analysis revealed adhesive failure observed for directly added particles while the other two groups demonstrated cohesive failure observed in the resin adhesive. On the other hand, direct addition of nHA resulted in partial remineralization of enamel (42% recovery in calcium content). Conclusions: TTEMA/TEGDMA enamel infiltrant could be used as a carrier for nano hydroxyapatite particles without compromising bond strength to early carious enamel lesions.

Comparative evaluation of the effect of 10%, 20%, and 30% guava seed extract on reversing compromised resin bond strength after enamel bleaching in 120 min, 10 min, and 5 min: An in vitro study.

Background:Bonding of composite with enamel and dentin gets compromised if the tooth is restored with composite immediately post bleaching. The application of antioxidants has shown to have a positive effect on it.Aim:The aim of this study was to evaluate and compare the effect of guava seed extract solutions in various concentrations on the shear bond strength (SBS) of composite resin to bleached enamel when applied for 5 min, 10 min, and 120 min.Materials and Methods:Fifty-five maxillary incisors were procured, and labial surfaces of 50 specimens were bleached with 37.5% hydrogen peroxide. These specimens were divided into 3 experimental groups: Group 1–3 comprising 15 specimens each (n = 15), and the remaining specimens were divided into two groups: Group 4 (positive control group) and Group 5 (negative control group). Groups 1–3 were further divided into 3 subgroups according to the application period of antioxidant: subgroups A, B, and C. Specimens were stored in distilled water for 24 h. SBS testing was done using the universal testing machine. Data were tabulated and subjected to statistical analysis using a three-way analysis of variance with post hoc Tukey's test.Results:Guava seed extract showed a complete reversal of the compromised bond strength, and promising results were seen with increased concentration.Conclusion:The use of antioxidants effectively reversed the compromised bond strength of bleached enamel, and an increase in the concentration of antioxidants reduces the duration of its application.

Influence of two different desensitizers on the shear bond strength of two newly introduced bonding agents following the total etch strategy: an in vitro study

Objective: Evaluate the shear bond strengths of two different dentin bonding agents following the pretreatment of dentine with two different desensitizing agents. Materials and methods: 60 premolar samples were grounded to expose the dentine. The teeth were categorized into three major groups. Each major group was subdivided into 2 subgroups of 10 samples each. Groups 1&amp;2 involved no pretreatment with desensitizer prior to the bonding agents application. Groups 3&amp;4 were pretreated with Gluma desensitizing agent prior to the use of All bond Universal as self-etching modality in group 3 and One Coat 7.0 in group 4. Groups 5&amp;6 involved pretreatment with MS Coat One desensitizer and use of All bond Universal and One Coat7.0 bonding agents respectively. Shear bond testing of the samples were then evaluated by the universal testing machine. Analysis of the data was done using One-way ANOVA and pair-wise comparison was performed using Tukey’s multiple comparison test. Results: Control groups in which no pretreatment was done with any desensitizing agent had the highest bond strength when compared to the experimental groups. Among the desensitizers, significantly higher bond strength was shown by Gluma than MS Coat One. Conclusion: Gluma with One Coat 7.0 can be used to decrease the post-operative sensitivity without compromising bond strength.

Reversal of Compromised Bond Strength of Bleached Enamel Using Cranberry Extract as an Antioxidant: an In Vitro Study.

Background and Objectives: Bleaching reduces the bond strength of enamel, if adhesive restorations are carried out immediately. Reversal of compromised bond strength of bleached enamel by application of antioxidant agents has been reported in the literature. The aim of the study is to assess the neutralizing effect of 6% cranberry (CB) solution on the bond strength of bleached enamel compared with that of 10% sodium ascorbate (SA) solution.Materials and Methods: Enamel surfaces of 64 extracted human premolar teeth were randomly divided into four groups based on the antioxidant used. Further subgrouping was done in Groups II, III, and IV dividing each group into subgroup A and subgroup B of eight teeth each based on whether the bonding was performed immediately or after a delay of 14 days postbleaching respectively. Shear bond strength (SBS) of the specimens was measured using a Universal testing machine. The data were then tabulated and statistically analyzed using one-way ANOVA (analysis of variance) and Tukey’s post-hoc parametric tests. A p-value of <0.05 was considered statistically significant.Results: The SBS measurements were compared among the four groups including the subgroups. The SBS was highest in the SA delayed bonding group and lowest in the bleached immediate bonding group.Conclusion: A 10% SA solution has proven superior to 6% CB solution in the reversal of compromised bond strength following bleaching.

Effect of cleaning protocol on silica deposition and silica-mediated bonding to Y-TZP

ObjectivesTo evaluate the effect of cleaning methods on the deposition of silica on yttria-stabilized zirconium dioxide (Y-TZP) surface and on the silane-silica mediated bond strength between Y-TZP and resin cement. MethodsY-TZP slabs were air-abraded with 30μm silica-coated alumina particles and distributed in three groups: no cleaning, cleaning with a stream of oil-free air/water spray for 5s and cleaning with an ultrasonic bath in water for 10min. The distribution of Si on the Y-TZP surfaces was recorded using energy dispersive spectroscopy (EDS). After the treatment was applied, Y-TZP slabs (n=20) received a primer application and resin cement cylinders were built on the surface. After storage (24h) in water storage or 3 months plus thermocycling; n=10), microshear bond strength test (μSBS) was performed. X- ray Photoelectron Spectroscopy (XPS) characterized the chemical bonds between the silica layer and the silane-containing primer. Data were analyzed using ANOVA and Tukey test, as well as Weibull analysis (α=0.05). ResultsCleaning method had a significant effect on the amount of Si deposited on zirconia surface (p<0.001) and, consequently, on bond strength (p<0.001). Storage/aging also had a significant effect on bond strength (p<0.001). Low values of Weibull moduli for bond strength were observed for all groups after aging. XPS showed silane-silica chemical interaction for all groups. SignificanceThe silica deposited by tribochemical coating to Y-TZP was removed by the cleaning methods evaluated, compromising bond strength. Stability of the bonding is also a concern when no cleaning method is applied.