Dentin Bond Integrity of Filled and Unfilled Resin Adhesive Enhanced with Silica Nanoparticles-An SEM, EDX, Micro-Raman, FTIR and Micro-Tensile Bond Strength Study

To Evaluate μTBS, Microleakage, and Resin Tag Length via Scanning Electron Microscopy of Different Resin Sealants Clinpro and Embrace Bonded to the Intact Enamel in Primary Molars

To evaluate the micro-tensile bond strength (μTBS), microleakage, and resin tag length via SEM of different resin sealants (Clinpro and Embrace) bonded to intact enamel as compared to the glass ionomer (GI) sealant in primary molars. Forty-eight fully erupted, intact second primary molars were obtained. The samples were randomly assigned to three groups according to the type of sealant used (n = 16): Group 1 (GI sealants), Group 2 (Clinpro), and Group 2 (Embrace). All restored teeth were submerged in water, keeping the temperature at 37°C for 24 h, and then thermocycled. Microleakage assessment was performed using a dye penetration test and μTBS using a universal testing machine. Scanning electron microscopy (SEM) was performed to assess the resin tag length and interface. Data analysis was conducted using ANOVA and post hoc Tukey tests. The significance level was set at p < 0.05. The lowest microleakage score (12.54 ± 0.09) and highest bond value (11.27 ± 0.11 MPa) were observed in Group 3 (Embrace) samples. The maximum values of marginal leakage (30.65 ± 0.04) and lowest bond scores (8.74 ± 0.02 MPa) were demonstrated by Group 1 (GI-based sealant). Intergroup comparisons indicated that Group 2 (Clinpro) and Group 3 exhibited comparable outcomes. Embrace and Clinpro displayed comparable bond integrity and marginal leakage. However, the authors of the existing study recommend that Embrace could be a better option in pediatric patients as it is difficult to maintain isolation with children.

Orthodontic Bracket to Enamel Pretreated With Nd: YAG and Er: Cr, YSGG Lasers Using Curcumin-Hydroxyapatite Nanoparticles Infused Adhesive: A FTIR, SEM Evaluation via Backscattered Electron Imaging

To evaluate the SBS, DC, and rheological valuation of experimental 1 wt % Cur-loaded-HNPs orthodontic adhesive to bond bracket to enamel surface treated with PA; Nd: YAG, and Er: Cr, YSGG lasers. Two adhesives were prepared experimental adhesive (EA) and EA loaded with 1-wt % Cur-HNP. Surface characterization of Cur-loaded HNP was performed under SEM along with EDS. Specimens were prepared and conditioned with three different strategies PA-gel, Er,Cr:YSGG laser, Nd: YAG laser. Following pretreatment brackets were bonded, samples underwent artificial aging and two samples from each enamel pretreatment regime were assessed under SEM via BSE. SBS testing was achieved via UTM followed by failure analysis using ARI. Modified and unmodified adhesives underwent DC using FTIR and rheological valuation was performed. SBS and DC were assessed using ANOVA and post hoc multiple comparison tests. The highest SBS was seen in the enamel surface treated with PA. The lowest SBS was remarked in the enamel surface treated with Nd: YAG laser. Based on ARI it was noted that modified adhesive containing Cur-HNP exhibited the highest number of failures between 1 and 2. No significant difference was observed between both adhesives in terms of DC. Adhesive modified with 1% Cur-HNP increased viscosity with a decrease in fluidity. The use of Er,Cr:YSGG laser for enamel pretreatment before bracket placement showed potential as a substitute for conventional acid etching, especially when combined with an experimental orthodontic adhesive containing Cur-HNPs.

Influence of Caries Eradication Techniques via Papacarie, and Er: YAG Laser With Different Adhesive Types Bonded to Composite Restoration in Primary Dentin. An SEM, μTBS, and Microleakage Assessment

Influence of different caries removal techniques using Papacarie and Erbium/yttrium-aluminum-garnet (Er: YAG) laser to different adhesives etch and rinse (ER) and self-etch (SE) restored via tooth-colored material on micro tensile bond strength (μTBS) and marginal leakage scores. Ninety-six extracted primary molars exhibiting moderate caries were allocated into three groups based on the caries removal technique. Group 1: Conventional bur, Group 2: Papacarie gel, and Group 3: Er: YAG laser. After caries removal, specimens from three groups were further allocated into two subgroups based on the type of adhesive used (n = 16). Two-step ER (A) and Two-step SE (B). Composite restoration was built and thermocycling was performed. Microleakage, μTBS, and failure mode were analyzed using a dye penetration test, a Universal testing machine, and a stereomicroscope respectively. Scanning electron microscopy (SEM) evaluation of the composite-CAD interface was performed. One-way ANOVA and the Tukey HSD test were utilized to compare microleakage and μTBS among investigated groups (p < 0.05). The lowest microlekage (13.56 ± 0.02) and highest μTBS (13.26 ± 0.11 MPa) was exhibited by Group 3B (Er: YAG laser-SE). However, the highest microleakage (45.62 ± 0.09) and lowest bond strength (9.34 ± 0.11 MPa) was exhibited by 1A (Conventional bur-ER) treated samples. For caries removal in primary dentition, the Er: YAG laser and Papacarié gel present themselves as appropriate alternatives. These non-invasive methods yield improved mechanical results when utilized with self-etch adhesive system.

Universal Adhesive Fortified With Inorganic Nanoparticles on Dentin Affected by Caries: A Comprehensive Study Utilizing SEM, EDX, Micro-Tensile Bond Strength and Antimicrobial Effectiveness

The present lab-based research aimed to assess the impact of different nanofillers: silver (Ag) chitosan (CH), and arginine nanoparticles (ArgNPs) infused in the eighth-generation universal adhesive (UA) on the antimicrobial potency, micro-tensile bond strength (μTBS), and degree of conversion (DC) bonded to carious-affected dentin (CAD) surface. Forty extracted human molars with Class 1 carious lesions were included. CAD was exposed and samples were allocated into four groups based on the type of adhesive (n = 10): Group 1 (UA), Group 2 (1 wt% AgNPs-UA), Group 3 (1 wt% CHNPs-UA), and Group 4 (1 wt% ArgNPs-UA). Survival rate assessment of inoculated Streptococcus mutans was performed after exposing them to different NPs. Characterization of tested nanoparticles (NPs) was also performed using scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX). The DC of modified and unmodified eighth-generation adhesive cured and uncured was assessed using Fourier transform infrared spectroscopy (FTIR). Composite was bonded on the CAD and samples underwent artificial aging. Beams were prepared for scanning electron microscopy (SEM) and μTBS analysis followed by failure mode assessment using a stereomicroscope. Statistical analysis was conducted using one-way analysis of variance (ANOVA) and Tukey's post hoc test to compare the means and standard deviations (SDs) between the different experimental groups (p < 0.05). Group 2 (1 wt% AgNPs-UA) samples exhibited the lowest S. mutans survival (0.10 ± 0.02 CFU/mL). Whereas Group 1 (UA) displayed the highest survival of tested bacteria (0.41 ± 0.08 CFU/mL). The maximum score of bond strength of composite to the CAD was detected in Group 2 (1 wt% AgNPs-UA) (21.11 ± 0.59 MPa) samples. However, the μTBS was minimal in Group 1 (UA) (16.18 ± 0.91 MPa). DC between the modified adhesive with 1 wt% AgNPs and the unmodified adhesive was comparable (p > 0.05). The incorporation of 1 wt% AgNPs in eighth-generation adhesives represents a favorable and reasonable alternative to unmodified adhesives when used on caries-affected dentin.

Post-Space Disinfectants With Sodium Hypochlorite and Methylene Blue Loaded in Silver and Quartz Nanoparticles Activated by Photodynamic Therapy. A SEM Analysis

Post-space disinfectants methylene blue loaded with silver (Ag) and Quartz nanoparticles (NPs) and MB alone activated by photodynamic therapy (PDT) on the survival of Enterococcus faecalis, smear layer (SL) removal efficacy, and extrusion bond strength (EBS) of fiber posts to canal dentin. Hundred mandibular premolars underwent root canal treatment using the rotary ProTaper system. The canals were obturated and post-space was prepared up to a length of 8 mm, maintaining a 5 mm seal. To assess antibacterial efficacy E. faecalis were inoculated in the canal (n = 20). The samples were then randomly allocated into four groups according to the canal disinfectant used to sterilize the canals. Group 1: 2.5% NaOCl+17% EDTA, Group 2: MB-PDT, Group 3: MB@QP-PDT, and Group 4: MB@AgNP-PDT (n = 25). SEM analysis was conducted on five samples from each disinfectant group to assess the removal of the SL. Survival rates were calculated (n = 5 from each group). Glass fiber post (GFP) was cemented to the root dentin of the remaining samples followed by artificial aging. Sectioning of the specimens was performed in all three-thirds of the canals. PBS was assessed followed by failure evaluation. ANOVA and Tukey post hoc test were used to compare the E. faecalis survival rate and PBS of fiber post among different investigated groups. Group 4 (MB@AgNP-PDT) treated canals exhibited the minimum survival rate (0.30 ± 0.04 CFU/mL) of E. faecalis and maximum PBS. However, the highest survival rate and minimum bond strength of GFP were observed in Group 1 (NaOCl+17% EDTA) and Group 2 (MB-PDT) treated teeth respectively. The highest SL removal was recorded in the coronal section of the samples of Group-4 disinfected with MB@AgNP-PDT. The lowest removal of SL was recorded in Group 2 samples sterilized with MB-PDT at apical one-third. Silver nanoparticles when utilized as nano-carriers to enhance the efficiency of MB activated by PDT, have been shown to exhibit the highest antimicrobial potency, improved capacity for SL removal and improved PBS.

Impact of silica nanoparticles incorporation on the properties of resin infiltration: an in vitro study

BACKGROUND

This study evaluated the effect of nano-silica (NS) incorporation with resin infiltrant on water sorption and solubility of resin infiltrant, mineral density of demineralized enamel, and resin tags penetration.

METHODS

NS (Sigma-Aldrich, St Louis, Missouri, USA) was added into the resin infiltrant (ICON, DMG, Hamburg, Germany) at two concentrations by weight. The tested groups were: ICON (control), ICON + 0.2, and ICON + 0.5 (n = 10 per group). Water sorption and solubility were assessed using mass variation after 60 days water storage. Mineral density and surface topography were assessed using micro-Computed Tomography scans. Resin tags penetration was measured using a scanning electron microscope. Data were analyzed using one-way Analysis of Variance and Tukey's post-hoc tests (P < .05).

RESULTS

ICON revealed the highest water sorption, solubility mean values (28.90, 7.61) followed by ICON + 0.2 (14.80, 4.82) and ICON + 0.5 (12.32, 0.81) respectively, and vice versa for resin tags penetration. Mineral density of demineralized enamel significantly increased after treatment with ICON + 0.2 and ICON + 0.5.

CONCLUSION

Incorporation of NS to resin infiltrant decreased its water sorption and solubility along with enhancing the mineral density of the demineralized enamel and the penetration of resin tags.

Photoactivated rose bengal-doped TiO2 nanoparticles modified fifth-generation adhesive on the survival rate of Streptococcus mutants and mechanical properties of tooth-colored restorative material to carious dentin

Assessment of the antimicrobial, micro tensile bond strength (μTBS), and degree of conversion (DC) of fifth-generation adhesive modified using photoactivated 0.5% rose bengal (RB) and photoactivated RB-doped titanium dioxide nanoparticles (TiO2NPs) in different concentrations (2% and 5%) as compared with the unmodified adhesive bonded to the carious affected dentin (CAD). Forty mandibular molars with caries progression up to the middle third of the dentin, as per the International Caries Detection and Assessment System (ICDAS) score of 4 and 5 were included. Specimens were divided into four groups based on etch and rinse adhesive (ERA) modification group 1: unmodified ERA, group 2: photoactivated 0.5% RB photosensitizer (PS) modified ERA, group 3: photoactivated RB-doped 2 wt% TiO2NPs adhesive, group 4: photoactivated RB-doped 5 wt% TiO2NPs adhesive. Followed by adhesive and composite restoration on the CAD surface. All the specimens were thermocycled and an assessment of μTBS and failure pattern analysis was performed. The antibacterial potency of RB and RB-doped TiO2NPs (2% and 5%) followed by their activation using visible light against Streptococcus mutans (S.mutans) were tested. The survival rate of S.mutans was assessed using the Kruskal-Wallis test. The analysis of μTBS involved the use of ANOVA, followed by a post-hoc Tukey honestly significant difference (HSD) multiple comparisons test. Group 1 (Unmodified ERA) (0.52 ± 0.31 CFU/mL) treated samples unveiled the highest means of bacterial survival and lowest μTBS (11.32 ± 0.63 MPa). Nevertheless, group 4: photoactivated RB-doped 5 wt% TiO2NPs adhesive displayed the lowest outcomes of S.mutans survival (0.11 ± 0.02 CFU/mL) and highest bond strength (18.76 ± 1.45 MPa). The photoactivated RB-doped 2 wt% TiO2NPs in adhesive demonstrated promising enhancements in both μTBS and antibacterial efficacy against S.mutans. However, it is noteworthy that this modification led to a decrease in the DC of the adhesive. RESEARCH HIGHLIGHTS: Unmodified ERA-treated samples unveiled the highest bacterial survival and the lowest μTBS. Photoactivated RB-doped 5 wt% TiO2NPs adhesive displayed the lowest S.mutans survival rate and highest bond strength. DC decreased with an increase in concentration of TiO2.

Titanium oxide and chitosan nanoparticles loaded in methylene blue activated by photodynamic therapy on caries affected dentin disinfection, bond strength, and smear layer removal efficacy

AIM

Effect of nanoparticles (NPs) loaded methylene blue (MB) mediated photodynamic therapy (PDT) on caries-affected dentin (CAD) against S.mutans, smear layer (SL) elimination, and shear bond strength (SBS) of single bottle 7th generation adhesive.

METHODOLOGY

Sixty human molars with carious lesions were selected. Samples were randomly allocated into four groups, based on the disinfection regime (n = 11) Group 1-(CHX), Group 2-(MB-PDT), Group 3-(MB-CNPs-PDT), and Group 4-(MB-TiO2NPs-PDT). Following disinfection S.mutans' survival rate was assessed using the pour plate method. Five specimens from each disinfection group were subjected to SL removal assessment using a scanning electron microscope (SEM). Bonding of 7th generation adhesive and composite restoration was performed on ten samples from each group. Artificial aging of the bonded samples was performed followed by SBS and failure mode analysis using a universal testing machine and stereomicroscope respectively. One-way analysis of variance (ANOVA) and Tukey post hoc test were used to analyze the data.

RESULTS

Group 3 (MB-CNPs-PDT) treated CAD surface unveiled the lowest survival rate (0.12 ± 0.02 CFU/mL) of tested bacteria, maximum SL removal (1.21 ± 0.35), and highest bond strength (13.42 ± 1.05). However, Group 1 (CHX) treated specimens displayed the highest survival rate (0.53 ± 0.11 CFU/mL) with the lowest SL removal (2.24 ± 0.30) and SBS (8.88 ± 0.73 MPa).

CONCLUSION

MB-CNPs-PDT appears to be a suitable alternative to CHX for CAD disinfection as it displayed better antibacterial efficacy, SL removal, and SBS with 7th generation single bottle adhesive.

Experimental and Chitosan-Infused Adhesive with Dentin Pretreated with Femtosecond Laser, Methylene Blue-Activated Low-Level Laser, and Phosphoric Acid

Aim: To prepare experimental adhesive (EA) with 1% and without chitosan nanoparticles on dentin conditioned with a conventional technique phosphoric acid (PA) compared with two different contemporary techniques: photodynamic therapy (PDT) and femtosecond laser (FSL). Method: The methodology consisted of synthesis of EA and 1% chitosan-modified adhesive (CMA). Scanning electron microscopy, dentin adhesive interface assessment, energy-dispersive spectroscopy, shear bond strength (SBS), degree of conversion (DC), and bond failure were assessed. Teeth were selected, disinfected, and mounted in acrylic up to the cementoenamel junction. Occlusal enamel was removed and teeth were randomly allocated into groups and conditioned. These included Group 1: samples treated with PA; Group 2: specimens conditioned with methylene blue photosensitizer (MBP) activated by PDT; and Group 3: samples conditioned with FSL. Following different conditioning regimes, specimens were bonded using 1% CMA and EA. The composite buildup was followed by SBS testing and a bond failure assessment. DC was assessed for both EA and CMA. Analysis of variance and Tukey's post hoc test were used to compare the mean and standard deviation of SBS and DC in different experimental groups, with a significance level of p < 0.05. Results: Dentin pretreated with etch and rinse demonstrated the highest bond strength with 1% CMA. Dentin conditioned with MBP activated by PDT and bonded to EA showed the lowest bond scores. Overall SBS values of 1% CMA were better than EA irrespective of the conditioning regime of dentin. The DC was higher in EA adhesive. This was followed by DC in 1% CMA. DC in EA was found to be comparable with 1% CMA. Conclusions: PA remains the gold standard for dentin conditioning. The incorporation of 1% chitosan in adhesive improves SBS and results in no change in DC. The use of FSL in dentin conditioning can be used as an alternative approach as it results in SBS within acceptable limits. The study was approved by the ethical board of King Saud University.

Modified experimental adhesive with sepiolite nanoparticles on caries dentin treated with femtosecond laser and photodynamic activated erythrosine. An in vitro study

AIM

To assess the effect of CAD surface conditioners and their effect on Ra and SBS of tooth-colored filling material adhered to CAD surface with adhesive modified with 1 % Sep-NPs. Also, the DC of modified EA and its effect on the rheological properties.

METHODS

Ninety human molars with carious extension up to the middle third of occlusal dentin were included. The teeth were then arbitrarily allocated into three groups based on the type of surface conditioning received (n = 30) Group 1 (PA), Group 2 (FS laser), and Group 3 (Ery PS). Ten samples from each group underwent Ra analysis using a stylus profiler. Twenty samples from each cohort were distributed into two subcategories based on the application of unmodified EA (A) and Sep-infiltrated EA (B). Composite restoration was built followed by SBS and failure mode analysis. Scanning electron microscopy and Energy dispersive X-ray EDX were assessed of sepiolite NPs. Degree of conversion (DC) and rheological analysis of the modified adhesive and unmodified adhesive were also performed. One-way analysis of variance (ANOVA) and the Tukey post hoc test were employed to conduct comparisons between the different groups.

RESULTS

The highest score of Ra and bond strength were displayed by Group 1B (PA + Sep-NPs filled EA) (17.32 ± 1.43 MPa) samples. Nevertheless, the lowest values were established by Group 3A (Ery-PS + EA) (13.45 ± 0.80 MPa) treated teeth. An increase in Ra resulted in a rise in SBS.DC decreased with the incorporation of 1 % Sep-NPs in EA compared to unmodified EA.

CONCLUSION

Conditioning of CAD with PA and FS laser shows high surface roughness and favorable adhesion to experimental adhesive modified with 1 % Sep-NPs. Modified adhesive with 1 % Sep-NPs decreases DC and rheological properties.

Effect of resin cement viscosities and surface roughness on shear bond strength of conditioned polymer infiltrated ceramic network

BACKGROUND

Hybrid ceramics bonding with the dentinal substrate is crucial for clinical success and longevity. To enhance adhesion, the surface of ceramic restorations is modified through various conditioning techniques AIM: Effect of Different Surface Conditioners Erbium-doped yttrium aluminum garnet (ER: YAG) laser and Low-level laser therapy (LLLT) activated Methylene blue (MB) on the surface roughness (Ra) and shear bond strength (SBS) of Polymer infiltrating ceramic network (PICN) discs bonded using different viscosity resin cement before and after thermal aging.

MATERIAL AND METHODS

One hundred and fifty human central incisors and one hundred and fifty-three PICN discs were prepared. PICN discs were randomly allocated into three groups based on the surface conditioning(n = 51) Group 1:10 % HF acid-S, Group 2: LLLT (MB), and Group 3: Er: YAG laser. Following conditioning Ra scores of ten samples were performed. Surface topography of samples was performed using a scanning electron microscope (SEM). Bonding of forty PICN discs from each conditioning group was performed with high (A) or low viscosity (B) dual-curing resin cement (n = 20 each). Each subgroup was divided into two cohorts and subjected to varying storage conditions. The SBS test and failure mode analysis were performed using a universal testing machine and stereomicroscope. Descriptive statistics of SBS and Ra for each group were analyzed using ANOVA and Tukey post hoc tests. HF acid-S attained the highest Ra scores.

RESULTS

Group 1A (HF-S+HIGH) samples achieved the highest SBS values at baseline. Group 3A, on the other hand, displayed the lowest bond score (Er: YAG laser+HIGH) after thermal aging. Intergroup comparison analysis at baseline unveiled that Group 1A and Group 1B (HF(S) + LOW) displayed no significant difference in their bond strength scores (p>0.05). Following artificial aging, it was observed that Group 2A (LLLT (MB) + HIGH) and Group 3A (Er:YAG laser + HIGH) ) presented comparable SBS(p > 0.05). Thermal aging decreased SBS significantly in all groups. PICN conditioned with HF-S results in high surface roughness.

CONCLUSION

PICN conditioned with HF acid with silane and bonded with low-viscosity resin cement to the dentinal substrate is preferable. Aging influences SBS.

Pretreatment of enamel with Riboflavin activated photodynamic therapy and Er, Cr: YSGG laser for bonding of orthodontic bracket with adhesive modified with cerium oxide nanoparticles

AIM

To assess the degree of conversion (DC) and shear bond strength (SBS) of experimental adhesive (EA) infused with and without 1 % Cerium oxide (CeO₂)-NPs on metallic bracket bonded to enamel conditioned with three different pretreatment regimes PDT-activated (Riboflavin) RF, ECY (Er, Cr: YSGG), and Phosphoric acid (PA).

MATERIAL AND METHOD

EA and EA modified with 1 % CeO₂-NPs were prepared. Characterization of CeO2NPs was assessed using a scanning electron microscope (SEM). Seventy-two premolars extracted due to periodontal or orthodontic reasons were disinfected. Samples were mounted and allocated into three groups according to enamel surface treatment before bracket bonding. Samples in Group 1 were pretreated with Traditional 37 % PA-gel; Specimens in Group 2 surface treated with RF-activated PDT, and samples in Group 3 were conditioned using ECY. Brackets were placed on conditioned surfaces and samples were aged and underwent SBS testing using UTM. ARI index was used to assess bond failure. DC was evaluated for both adhesives using FTIR. ANOVA and Tukey post hoc test were used to compare the means and standard deviation (SD) of SBS and DC in different experimental groups.

RESULTS

Enamel conditioned with PA and RF activated by PDT demonstrated comparable bond values with 1 % CeO2 infused in EA and EA (p>0.05).ARI analysis shows that enamel conditioned with PA and RF activated by PDT showed the majority of failure types between 1 and 2 irrespective of the type of adhesive. DC value in EA (73.28±8.37) was the highest and comparable to 1 % CeO2 infused in EA (66.48±6.81) CONCLUSION: RF-activated PDT can be used alternatively to 37 % PA for enamel conditioning when bonding metallic brackets. Infiltration of 1 % CeO2 NPs in EA improves SBS irrespective of the type of enamel conditioning. Infusion of 1 % CeO2 NPs in EA demonstrates no significant difference in DC compared to EA.

Dentin Bonding Durability of Four Different Recently Introduced Self-Etch Adhesives

The objectives of this study were to evaluate the bonding durability of four different self-etch adhesives to dentin after 24 h and thermal cycling (TC) and to measure the degree of polymerization conversion (DC) in situ. Two-step self-etch adhesives, Clearfil SE Bond 2 (SE2, Kuraray Noritake Dental) and G2-Bond Universal (G2B, GC), and one-step self-etch adhesives, Scotchbond™ Universal Plus Adhesive (SBU, 3M ESPE) and Clearfil Universal Bond Quick (UBQ, Kuraray Noritake Dental), were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces. The adhesives were applied according to the manufacturers' instructions. After resin composite buildup and 24 h water storage, the specimens were sectioned into beams and all groups were subjected to thermal stress for 0, 10,000 (10k), or 20,000 (20k) cycles followed by micro-tensile bond strength (µTBS) testing. In situ DC was investigated with a laser Raman microscope. The µTBS data were statistically analyzed and subjected to a Weibull analysis. The different groups were compared at the characteristic strength (63.2% probability of failure) (α = 0.05). Two-Way ANOVA was used to show the effect of different adhesives and thermal cycling on the mean DC% followed by Tukey's multiple comparison post hoc test. G2B/TC10k resulted in a significant increase in the µTBS compared to TC0. SBU/TC20k showed significantly higher µTBS compared to TC0. For comparison between different tested adhesives, SBU showed a significantly lower µTBS compared to G2B after TC10k. G2B and SBU showed a greater number of adhesive failures after TC. Mean DC% was different for each adhesive. The newly developed MDP- and HEMA-free 2-SEA showed similar bonding performance with the gold-standard 2-SEA. However, there is still room for further improvement in terms of SEAs.

Aluminum zirconate nanoparticles in etch and rinse adhesive to caries affected dentine: An in-vitro scanning electron microscopy, elemental distribution, antibacterial, degree of conversion and micro-tensile bond strength assessment

To incorporate different concentrations of Al2O9Zr3 (1%, 5%, and 10%) nanoparticles (NP) into the ER adhesive and subsequently assess the impact of this addition on the degree of conversion, μTBS, and antimicrobial efficacy. The current research involved a wide-ranging examination that merged various investigative techniques, including the application of scanning electron microscopy (SEM) for surface characterization of NP coupled with energy-dispersive x-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, μTBS testing, and microbial analysis. Teeth were divided into four groups based on the application of modified and unmodified three-step ER adhesive primer. Group 1 (0% Al2O9Zr3 NPs) Control, Group 2 (1% Al2O9Zr3 NPs), Group 3 (5% Al2O9Zr3 NPs), and Group 4 (10% Al2O9Zr3 NPs). EDX analysis of Al2O9Zr3 NPs was performed showing elemental distribution in synthesized NPs. Zirconium (Zr), Aluminum (Al), and Oxides (O2). After primer application, an assessment of the survival rate of Streptococcus mutans was completed. The FTIR spectra were analyzed to observe the characteristic peaks indicating the conversion of double bonds, both before and after the curing process, for the adhesive Etch and rinse containing 1,5,10 wt% Al2O9Zr3 NPs. μTBS and failure mode assessment were performed using a Universal Testing Machine (UTM) and stereomicroscope respectively. The μTBS and S.mutans survival rates comparison among different groups was performed using one-way ANOVA and Tukey post hoc (p = .05). Group 4 (10 wt% Al2O9Zr3 NPs + ER adhesive) specimens exhibited the minimum survival of S.mutans (0.11 ± 0.02 CFU/mL). Nonetheless, Group 1 (0 wt% Al2O9Zr3 NPs + ER adhesive) displayed the maximum surviving S.mutans (0.52 ± 0.08 CFU/mL). Moreover, Group 2 (1 wt% Al2O9Zr3 NPs + ER adhesive) (21.22 ± 0.73 MPa) samples displayed highest μTBS. However, the bond strength was weakest in Group 1 (0 wt% Al2O9Zr3 NPs + ER adhesive) (14.13 ± 0.32 MPa) study samples. The etch-and-rinse adhesive exhibited enhanced antibacterial activity and micro-tensile bond strength (μTBS) when 1% Al2O9Zr3 NPs was incorporated, as opposed to the control group. Nevertheless, the incorporation of Al2O9Zr3 NPs led to a decrease in DC. RESEARCH HIGHLIGHTS: 10 wt% Al2O9Zr3 NPs + ER adhesive specimens exhibited the minimum survival of S.mutans. 1 wt% Al2O9Zr3 NPs + ER adhesive samples displayed the most strong composite/CAD bond. The highest DC was observed in Group 1: 0 wt% Al2O9Zr3 NPs + ER adhesive.

Orthodontic adhesive loaded with different proportions of ZrO2 silver-doped nanoparticles: An in vitro μTBS, SEM, EDX, FTIR, and antimicrobial analysis

Zirconium dioxide silver-doped nanoparticles (ZrO2AgDNPs) impacts the adhesive material in terms of its physical characteristics, antimicrobial properties, degree of conversion (DC), and micro-tensile bond strength (μTBS) of orthodontic brackets to the enamel surface. A comprehensive methodological analysis utilizing a range of analytical techniques, including scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, DC analysis, and μTBS testing. A light-curable orthodontic adhesive, specifically Transbond XT, was combined with ZrO2AgDNPs at 2.5% and 5%. As a control, an adhesive with no incorporation of ZrO2AgDNPs was also prepared. The tooth samples were divided into three groups based on the weightage of NPs: group 1: 0% ZrO2AgDNPs (control), group 2: 2.5 wt% ZrO2AgDNPs, and group 3: 5 wt% ZrO2AgDNPs. EDX graph demonstrated silver (Ag), Zirconium (Zr), and Oxygen (O2), The antibacterial efficacy of adhesives with different concentrations of NPs (0%, 2.5%, and 5%) was assessed using the pour plate method. The FTIR spectra were analyzed to identify peaks at 1607 cm-1 corresponding to aromatic CC bonds and the peaks at 1638 cm-1 indicating the presence of aliphatic CC bonds. The μTBS was assessed using universal testing machine (UTM) and bond failure of orthodontic brackets was seen using adhesive remanent index (ARI) analysis. Kruskal-Wallis test assessed the disparities in survival rates of Streptococcus mutans. Analysis of variance (ANOVA) and post hoc Tukey multiple comparisons test calculated μTBS values. The lowest μTBS was observed in group 1 adhesive loaded with 0% ZrO2AgDNPs (21.25 ± 1.22 MPa). Whereas, the highest μTBS was found in group 3 (26.19 ± 1.07 MPa) adhesive loaded with 5% ZrO2AgDNPs. ZrO2AgDNPs in orthodontic adhesive improved μTBS and has acceptable antibacterial activity against S mutans. ZrO2AgDNPs at 5% by weight can be used in orthodontic adhesive alternative to the conventional method of orthodontic adhesive for bracket bonding. RESEARCH HIGHLIGHTS: The highest μTBS was found in orthodontic adhesive loaded with 5% ZrO2AgDNPs. ARI analysis indicates that the majority of the failures fell between 0 and 1 among all investigated groups. The colony-forming unit count of S. mutans was significantly less in orthodontic adhesive loaded with nanoparticles compared with control. The 0% ZrO2AgDNPs adhesive showed the highest DC.

Visible light-activated curcumin-doped zinc oxide nanoparticles integrated into orthodontic adhesive on Micro-tensile bond strength, degree of conversion, and antibacterial effectiveness against Staphylococcus Aureus. An investigation using scanning electron microscopy and energy-dispersive X-ray spectroscopy

AIM

To acquire a thorough comprehension of the photoactivated Cur-doped ZnONPs at different concentrations 0%, 2.5%, and 5% on the physical qualities, antibacterial efficacy, degree of conversion, and μshear bond strength between orthodontic brackets and the enamel surface.

MATERIAL AND METHODS

An extensive investigation was carried out utilizing a range of analytical methods, scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, micro tensile bond strength (μTBS) testing, and evaluation of antibacterial effectiveness. Cur-doped ZnONPs at concentrations of 2.5% and 5% were blended with Transbond XT, a light-curable orthodontic adhesive. A control group without the addition of Cur-doped ZnONPs was also prepared. The tooth samples were categorized into three groups based on the weight percentage of NPs: Group 1 (control) with 0% Cur-doped ZnONPs, Group 2 with 2.5 wt% Cur-doped ZnONPs, and Group 3 with 5 wt% Cur-doped ZnONPs. The SEM technique was employed to analyze the morphological characteristics of Cur-doped ZnONPs and ZnONPs. The composition and elemental distribution of the modified Cur-doped ZnONPs were assessed using energy-dispersive X-ray spectroscopy. The effectiveness of NPs at various concentrations against S.Mutans was gauged through the pour plate method. DC of Cur-doped ZnONPs at a region of 1608 cm-1 to 1636 cm-1 for the cured area, whereas the uncured area spanned the same range of 1608 cm-1 to 1636 cm-1 was assessed. The Adhesive Remnant Index (ARI) approach was utilized to investigate the bond failure of orthodontic brackets, while a Universal Testing Machine (UTM) was utilized to test μTBS. The Kruskal-Wallis test was employed to investigate variations in S.mutans survival rates. To determine the μTBS values, analysis of variance (ANOVA) and the post hoc Tukey multiple comparisons test were used.

RESULTS

The maximum μTBS was given and documented in group 3: 5 wt% Cur-doped ZnONPs (21.21 ± 1.53 MPa). The lowest μTBS was given in group 2: 2.5 wt% Cur-doped ZnONPs (19.58 ± 1.27 MPa). The highest efficacy against S.mutans was documented in group 3 in which 5 wt% Cur-doped ZnONPs (0.39 ± 0.15). The lowest efficacy was seen in group 1 in which no Cur-doped ZnONPs were used (6.47 ± 1.23). The ARI analysis indicated that the predominant failure was between scores 0 and 1 among all experimental groups. Control group 1 which was not modified showed the highest DC (73.11 ± 4.19).

CONCLUSION

Orthodontic adhesive, containing 5% Cur-doped ZnONPs photoactivated with visible light exhibited a favorable impact on μTBS and indicated enhanced antibacterial efficacy against S.mutans. Nevertheless, it was observed that the addition of Cur-doped ZnONPs at different concentrations (2.5%,5%) resulted in a decrease in the monomer-to-polymer ratio compromising DC.

Effects of dimethyl sulfoxide pretreatment on the bonding properties of fluorotic dentin of different severity: An in vitro study

STATEMENT OF PROBLEM

Bonding to fluorotic dentin is weaker than to sound dentin, but methods to improve bonding have not been well addressed.

PURPOSE

The purpose of this in vitro study was to investigate the effects of dimethyl sulfoxide (DMSO) pretreatment on the bond strength and resin-dentin surface of fluorotic dentin of different severity.

MATERIAL AND METHODS

Phosphoric acid-etched dentin specimens exhibiting mild fluorosis (ML-F), moderate fluorosis (MD-F), and severe fluorosis (SE-F) were randomly bonded with Single Bond 2 (SB2) pretreated with 50% DMSO (experimental groups) or deionized water (control groups). The bonded teeth were sectioned for microshear bond strength (μSBS) testing immediately or after aging, for micromorphology observation of the bonding interface under a scanning electron microscope, and for resin tags and microleakage evaluation under a confocal laser scanning microscope. The degree of conversion of the adhesive resin was calculated by Fourier transform infrared spectroscopy. According to varying bonding steps, the mineralized dentin powders of ML-F, MD-F, and SE-F were randomly divided into 4 subgroups (blank, PA, PA+SB2, and PA+DMSO+SB2) and incubated in artificial saliva to examine the level of enzymatic degradation product of type I collagen. Data were analyzed by using ANOVA and the Tukey test (α=.05).

RESULTS

Dental fluorosis and thermocycling had negative effects on μSBS (P<.001), while DMSO pretreatment preserved or even improved μSBS (P<.001). DMSO had no influence on the degree of conversion (P=.618). Significant effects were found for bonding steps (P<.001), but not that of dental fluorosis (P=.131) on the enzymatic degradation product of type I collagen. Images showed sparser and more expanded collagen fibril meshwork, deeper resin penetration, and less microleakage in the experimental groups.

CONCLUSIONS

DMSO pretreatment provided increased and durable dentin bonding to fluorotic dentin probably by dispersing collagen fibrils into a sparser network and inhibiting the degradation of type I collagen.

Salicylic acid-functionalised chitosan nanoparticles restore impaired sucrose metabolism in the developing anther of cotton (Gossypium hirsutum) under heat stress

Nanotechnology provides tremendous potential in agriculture, mitigating climate change impact and improving abiotic stress management strategy. Chitosan nanoparticles (NCS) were synthesised using the ion gelation method and characterised for size (75.5nm in particle size analyser), shape (spherical under scanning electron microscopy) and stability (132.2mV zeta potential). Further, salicylic acid was incorporated into NCS to craft salicylic acid-functionalised chitosan nanoparticles (SA-NCS) and illustrated for size (517nm), shape (spherical) and stability (197.1mV). The influence of the exogenous application of SA-NCS (0.08%) was studied at the reproductive stage of three genotypes of cotton (Gossypium hirsutum ): (1) heat-tolerant Solar-651 BGII; (2) moderately heat-tolerant Solar-701 BGII; and (3) heat-susceptible Solar-805 BGII, exposed to different temperature regimes: (1) H1 (optimal), 32/20±2°C; (2) H2 (sub-optimal), 38/24±2°C; H3 (supra-optimal), 45/30±2°C. Heat stress significantly reduces carbon-fixing Rubisco, enzymes related to sucrose metabolism and pollen tube length. Considering three genotypes and reproductive stages (sepal and anther tissues), activities of Rubisco (sepals), invertase (sepals), sucrose phosphate synthase (anthers), sucrose content (sepals) and pollen tube length were elevated under high-temperature regimes, signifying better source to sink transposition of sucrose influenced by SA-NCS. The study provides new insights into SA-NCS to improve source-sink imbalance and restore sucrose metabolism for better growth of reproductive structure under heat stress in cotton.

Analyses of Experimental Dental Adhesives Based on Zirconia/Silver Phosphate Nanoparticles

This study aimed to evaluate the incorporation of zirconia/silver phosphate nanoparticles to develop experimental dental adhesives and to measure their physical and mechanical properties. The nanoparticles were synthesized by the sonication method, and the phase purity, morphological pattern, and antibacterial properties with Staphylococcus aureus and Pseudomonas aeruginosa were assessed. The silanized nanoparticles were incorporated (0, 0.15, 0.25, and 0.5 wt.%) into the photoactivated dimethacrylate resins. The degree of conversion (DC) was assessed, followed by the micro-hardness and flexural strength/modulus test. Long-term color stability was investigated. The bond strength with the dentin surface was conducted on days 1 and 30. The transmission electron microscopy and X-ray diffractogram confirmed the nano-structure and phase purity of the particles. The nanoparticles showed antibacterial activities against both strains and inhibited biofilm formation. The DC range of the experimental groups was 55-66%. The micro-hardness and flexural strength increased with the concentration of nanoparticles in the resin. The 0.5 wt.% group showed significantly high micro-hardness values, whereas a non-significant difference was observed between the experimental groups for flexural strength. The bond strength was higher on day 1 than on day 30, and a significant difference was observed between the two periods. At day 30, the 0.5 wt.% showed significantly higher values compared to other groups. Long-term color stability was observed for all the samples. The experimental adhesives showed promising results and potential to be used for clinical applications. However, further investigations such as antibacterial, penetration depth, and cytocompatibility are required.

Evolution of Biomimetic Approaches for Regenerative and Restorative Dentistry

Biomimetics refers to human-made processes, substances, systems, or devices that imitate nature. The art and science of designing and building biomimetic apparatus are called biomimetics. This method can be widely used in dentistry to restore the structure and function of normal tooth structure. Traditional approaches to treating damaged and decayed teeth require more aggressive preparation to place a "strong," stiff restoration. The emphasis was made on the strength of the restoration as well as its function and mechanical properties, despite several disadvantages like tooth fracture, making future treatment more difficult and invasive. This review paper will seek to provide a clear explanation of its scope, different fields of biomimetic dentistry, and materials used in biomimetics that improve the strength of the tooth.

Effects of carbodiimide combined with ethanol-wet bonding pretreatment on dentin bonding properties: an in vitro study

Purpose

This study evaluated the combined effects of Carbodiimide (EDC) and ethanol-wet bonding (EWB) pretreatment on the bond strength and resin-dentin surface.

Methods

Phosphoric acid-etched dentin specimens were randomly divided into five groups based on the following pretreatments: deionized water (control), EWB, 0.3M EDC in water (EDCw), EDC water solution combined EWB (EDCw + EWB), and 0.3M EDC in ethanol (EDCe). A scanning electron microscope (SEM) was used to observe the morphology of collagen fibrils on the demineralized dentin matrix in each group after pretreatment. The adhesives Prime & Bond NT (PB) (Dentsply De trey, Konstanz, Germany) or Single bond 2 (SB) (3M ESPE, St. Paul, MN, USA) was applied after pretreatments, and a confocal laser scanning microscope (CLSM) was used to evaluate the quality of resin tags. The degree of conversion (DC) of the adhesive was investigated by Fourier transform infrared spectroscopy (ATR-FTIR). The dentin was first bonded with resin and bathed in water at 37 °C for 24 h. Half of them were subjected to 10, 000 cycles in a thermocycler between 5 °C and 55 °C before a microshear bond strength (µSBS) test. The statistical methods were Analysis of Variance (ANOVA) and a Tukey post hoc test at α = 0.05.

Results

The µSBS was significantly affected by pretreatments (p < 0.001), adhesives (p < 0.001), and aging conditions (p < 0.001) as revealed by the three-way ANOVA. The EDCw, EDCw + EWB, and EDCe groups significantly increased the µSBS; the EDCw + EWB and EDCe groups produced the highest µSBS. In the EDC-containing groups, the SEM showed at the collagen fibrils in the dentin matrix formed a three-dimensional network structure in the tubules after cross-linking into sheets, and the hybrid layer formed thicker resin tags under a CLSM. In the EDC-containing groups, the CLSM observed an increase in the length of resin tags. PB showed a higher DC and bonding strength than SB, and the five pretreatment groups tested did not affect the DC of the two adhesives.

Conclusions

In etch-and-rinse bonding system, EDC combined with EWB pretreatment can improve the quality of the hybrid layer and enhance the mechanical properties of demineralized dentin matrix. Pretreatment with EDC-ethanol solution may be a new clinically friendly option for enhancing dentin bonding durability.

Influence of Novel Experimental Light-Cured Resin Cement on Microtensile Bond Strength

The purpose of this study was to evaluate the microtensile bond strength (µTBS) and Knoop hardness number (KHN) of a novel experimental light-cured resin cement (HL). Eighteen flat dentin surfaces of human molars were polished using #600 SiC paper and bonded to CAD/CAM resin blocks with the respective resin cements and composites: HL, Panavia V5 (PV), and Clearfil AP-X (AP). All specimens were stored in distilled water at 37 °C for 24 h and 7 days. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) observations were performed to evaluate filler morphology and to detect the elements. The resin cements had a significant effect on the immediate µTBS (F = 22.59, p < 0.05) and after water storage µTBS (F = 22.83, p < 0.05). Significant differences (p < 0.05) in the KHN between the tested materials were observed, and HL indicated the highest KHN when compared with PV. HL showed a combination of the regular-shaped filler and spherical-shaped filler within the matrix. Silicon was detected in HL from the EDX evaluation. HL exhibited better bonding performance and polymerization, which may have contributed to the improvement of the adhesive strength.

The Effect of Dentifrice on Micro-Hardness, Surface Gloss, and Micro-Roughness of Nano Filled Conventional and Bulk-Fill Polymer Composite-A Micro Indentation and Profilometric Study

The aim of the present study was to evaluate the effect of brushing with two whitening dentifrices (Colgate Optic White (COW) and Colgate Optic White Charcoal (COC)) on surface gloss, micro-roughness, and micro-hardness of nanostructured hybrid conventional (Z350) and bulk-fill (Tetric N Ceram bulk-fill) polymer composite. In total, 96 disk samples using two nano-hybrid composite polymers (Z350 and Tetric N Ceram Bulk-fill) were prepared. All specimens were exposed to two different dentifrices (COW and COC), resulting in four main subgroups in the study. Specimens were assessed for surface gloss, micro-roughness (Ra), and micro-hardness using standardized methodology. Means and standard deviations of properties compared using paired t-test, one-way and two-way ANOVA, and post hoc test. The presence of dentifrices did not show any significant difference in micro-hardness values of Z350 (p > 0.05), whereas micro-hardness of bulk-fill composite significantly reduced on dentifrices exposure (p ≤ 0.05). Bulk-fill polymer composite showed significant reduction in gloss after dentifrice exposure (p < 0.05), however, Z350 showed no significant loss of gloss due to dentifrices (p > 0.05). A significant increase in Ra was observed for both resin materials after exposure to dentifrices (COC and COW). Conventional resin composite (Z350) showed comparable surface hardness and gloss before and after dentifrice exposure, however, micro-roughness increased significantly due to dentifrice exposure. Bulk-fill resin (Tetric N Ceram) showed significant loss of micro-hardness and gloss and increase in micro-roughness on dentifrice exposure. Conventional nano-hybrid composite polymer showed better durability in resisting loss of surface properties compared to bulk-fill resin polymer in the present experiment.

The Molecular and Mechanical Characteristics of Biomimetic Composite Dental Materials Composed of Nanocrystalline Hydroxyapatite and Light-Cured Adhesive

The application of biomimetic strategies and nanotechnologies (nanodentology) has led to numerous innovations and provided a considerable impetus by creating a new class of modern adhesion restoration materials, including different nanofillers. An analysis of the molecular properties of biomimetic adhesives was performed in this work to find the optimal composition that provides high polymerisation and mechanical hardness. Nanocrystalline carbonate-substituted calcium hydroxyapatite (nano-cHAp) was used as the filler of the light-cured adhesive Bis-GMA (bisphenol A-glycidyl methacrylate). The characteristics of this substance correspond to the apatite of human enamel and dentin, as well as to the biogenic source of calcium: avian eggshells. The introduction and distribution of nano-cHAp fillers in the adhesive matrix resulted in changes in chemical bonding, which were observed using Fourier transform infrared (FTIR) spectroscopy. As a result of the chemical bonding, the Vickers hardness (VH) and the degree of conversion under photopolymerisation of the nano-cHAp/Bis-GMA adhesive increased for the specified concentration of nanofiller. This result could contribute to the application of the developed biomimetic adhesives and the clinical success of restorations.

Influence of Concentration Levels of β-Tricalcium Phosphate on the Physical Properties of a Dental Adhesive

Our study assessed the influence of integrating 5% and 10% tricalcium phosphate (β-TCP-Ca₃(PO₄)₂.) nanoparticles into a dental adhesive on the adhesive’s bonding. To evaluate the filler nanoparticles, scanning electron microscopy (SEM), Energy Dispersive X-Ray (EDX) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and micro-Raman spectroscopy techniques were used. Shear Bond strength (SBS) testing, degree of conversion (DC) analysis, investigation of the adhesive–dentin interface, and biofilm experiments were conducted. The SEM micrographs revealed non-uniform agglomerates, while the EDX demonstrated the existence of oxygen ‘O’ (24.2%), phosphorus ‘P’ (17.4%) and calcium ‘Ca’ (60.1%) in the β-TCP nanoparticles. The FTIR and micro-Raman spectra indicated characteristic bands for β-TCP containing materials. The 10 wt.% β-TCP adhesive presented the highest SBS values (NTC-10 wt.% β-TCP: 33.55 ± 3.73 MPa, TC-10 wt.% β-TCP: 30.50 ± 3.25 MPa), followed by the 5 wt.% β-TCP adhesive (NTC-5 wt.% β-TCP: 32.37 ± 3.10 MPa, TC-5 wt.% β-TCP: 27.75 ± 3.15 MPa). Most of the detected failures after bond strength testing were adhesive in nature. The β-TCP adhesives demonstrated suitable dentin interaction by forming a hybrid layer (with few or no gaps) and resin tags. The β-TCP adhesives (10 wt.%) revealed lower DC values compared to control. The incorporation of 5 and 10 wt.% concentrations of β-TCP particles resulted in an increase in SBS values. A linear decline in DC values was witnessed when the nanoparticle concentration was increased. Further research focusing on exploring the influence of higher filler concentrations on adhesive’s properties is recommended.

Influence of TiO2 and ZrO2 Nanoparticles on Adhesive Bond Strength and Viscosity of Dentin Polymer: A Physical and Chemical Evaluation

The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO₂) or zirconium oxide (ZrO₂) to yield 5% TiO₂ and 5% ZrO₂ adhesives, respectively, and then analyze the impact of this reinforcement on various mechanical properties of the adhesives. The EA contained a blend of monomers such as bisphenol A glycol dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and ethyl 4-dimethylamino benzoate and camphorquinone. The EA included ethyl 4-dimethylamino benzoate and camphorquinone photo-initiators, and diphenyliodonium hexafluorophosphate (DPIHP) was also included to act as an electron initiator. The TiO₂ and ZrO₂ nanoparticles were incorporated into the EA post-synthesis. To characterize the filler nanoparticles, scanning electron microscopy (SEM) and line-energy dispersive X-ray (EDX) spectroscopy were performed. The adhesives were characterized by analyzing their rheological properties, shear-bond strength (SBS), and interfacial failure types. Further, the resin-dentin interface was also analyzed via SEM. The TiO₂ nanoparticles were spherically shaped on the SEM micrographs, while the ZrO₂ nanoparticles were seen as non-uniformly shaped agglomerates. The EDX mapping demonstrated the presence of Ti and oxygen for TiO₂ and Zr and oxygen for the ZrO₂ nanoparticles. Both 5% TiO₂ and 5% ZrO₂ adhesives revealed decreased viscosity as compared with the EA. The 5% TiO₂ adhesive demonstrated higher SBS values for both non-thermocycled (NTC) and thermocycled samples (NTC: 25.35 ± 1.53, TC: 23.89 ± 1.95 MPa), followed by the 5% ZrO₂ adhesive group (NTC: 23.10 ± 2.22, TC: 20.72 ± 1.32 MPa). The bulk of the failures (>70%) were of adhesive type in all groups. The SEM analysis of the resin-dentin interface revealed the development of a hybrid layer and resin tags (of variable depth) for the EA and 5% TiO₂ groups. However, for the 5% ZrO₂ group, the hybrid layer and resin tag establishment appeared compromised. Reinforcement of the EA with TiO₂ or ZrO₂ caused an increase in the adhesive's SBS (with the 5% TiO₂ group demonstrating the highest values) in comparison with the EA (without nanoparticles). However, both nanoparticle-containing adhesives revealed decreased viscosity compared with the EA (without nanoparticles). Further studies investigating the impact of diverse filler concentrations on the properties of adhesives are suggested.

Application of β-Tricalcium Phosphate in Adhesive Dentin Bonding

The study aimed at synthesizing β-tricalcium phosphate (β-TCP) nanoparticles and comparing the mechanical properties and dentin interaction of two adhesives: experimental adhesive (EA) and EA with 5 wt.% β-TCP nanoparticles (β-TCP-5%). These filler nanoparticles were synthesized and then characterized with scanning electron microscopy (SEM) and micro-Raman spectroscopy. The β-TCP nanoparticles were incorporated in the adhesives to form two groups: gp-1: EA (control) and gp-2: β-TCP-5%. These adhesives were characterized by SEM, energy-dispersive X-ray (EDX) spectroscopy and were also assessed for their micro-tensile bond strength (μTBS) with (TC) and without thermocycling (NTC). Fourier Transform Infrared (FTIR) spectroscopy was performed to evaluate the degree of conversion (DC) of two adhesives. The β-TCP filler was seen as irregularly shaped agglomerates on SEM. The micro-Raman spectra revealed characteristic peaks associated with β-TCP nanoparticles. Both adhesives presented suitable dentin interaction, which was demonstrated by the formation of resin tags of variable depths. The EDX analysis verified the existence of calcium (Ca) and phosphate (P) for the β-TCP-5% group. The greatest μTBS values were shown by β-TCP-5% group samples when they were non-thermocycled (NTC) (β-TCP-5%-NTC: 34.11 ± 3.46) followed by the thermocycled (TC) samples of the same group (β-TCP-5%-TC: 30.38 ± 3.66), compared with the EA group. Although the DC presented by β-TCP-5% group was comparable to the EA group, it was still lower. The addition of β-TCP nanoparticles in the adhesive improved its μTBS and resulted in a suitable dentin interaction, seen in the form of hybrid layer and resin tag formation. Nonetheless, a decreased DC was observed for the β-TCP-5% adhesive. Future studies probing the effect of different filler concentrations on various properties of the adhesive are warranted.

Assessment of Bond Integrity, Durability, and Degree of Conversion of a Calcium Fluoride Reinforced Dentin Adhesive

Our study aimed to synthesize and compare the mechanical properties and dentin interaction of two adhesives; experimental adhesive (EA) and EA containing 5 wt.% calcium fluoride (CaF₂) nano-crystals (CaF₂ adhesive-CAFA). CaF₂ nano-crystals were synthesized by reacting two solutions (containing calcium and fluoride) in a glass chamber using a heated air system. The EA was produced using a mix of monomers, photo-initiators, camphorquinone, and electron initiators. The synthesized CaF₂ nano-crystals were centrifuged to guarantee that inside the adhesive there is homogenized dispersion of the filler particles. Their integration in the EA yielded two groups; Gp-1: EA (without CaF₂, control) and Gp-2: (5 wt.% CaF₂ containing adhesive, CAFA). Sixty teeth were prepared and set to form bonded specimens using the two adhesives. The CaF₂ nano-crystals were irregularly shaped with an average particle size of 30–200 nm. The highest μTBS values were obtained for CAFA-non-thermocycled (NTC) samples (32.63 ± 3.15), followed by EA-NTC (31.80 ± 3.75) specimens. On thermocycling (TC), both adhesive groups presented lower μTBS values (CAFA-TC: 29.47 ± 3.33 and EA-TC: 24.04 ± 3.69). Hybrid layer (HL) formation and resin tags of varying depths were perceived for both adhesive groups. The EDX analysis demonstrated the presence of carbon (C), silica (Si), calcium (Ca), and fluoride (F) for CAFA group. Micro-Raman spectroscopy revealed distinct peaks for CaF₂ nano-crystals. The CAFA group presented the greatest DC. The addition of CaF₂ nano-crystals in the adhesive caused improved bond μTBS and DC. The incorporation also demonstrated suitable dentin interaction, depicted by appropriate HL and resin tag development.

Synergistic Effect of Bioactive Inorganic Fillers in Enhancing Properties of Dentin Adhesives-A Review

Dentin adhesives (DAs) play a critical role in the clinical success of dental resin composite (DRC) restorations. A strong bond between the adhesive and dentin improves the longevity of the restoration, but it is strongly dependent on the various properties of DAs. The current review was aimed at summarizing the information present in the literature regarding the improvement of the properties of DAs noticed after the addition of bioactive inorganic fillers. From our search, we were able to find evidence of multiple bioactive inorganic fillers (bioactive glass, hydroxyapatite, amorphous calcium phosphate, graphene oxide, calcium chloride, zinc chloride, silica, and niobium pentoxide) in the literature that have been used to improve the different properties of DAs. These improvements can be seen in the form of improved hardness, higher modulus of elasticity, enhanced bond, flexural, and ultimate tensile strength, improved fracture toughness, reduced nanoleakage, remineralization of the adhesive-dentin interface, improved resin tag formation, greater radiopacity, antibacterial effect, and improved DC (observed for some fillers). Most of the studies dealing with the subject area are in vitro. Future in situ and in vivo studies are recommended to positively attest to the results of laboratory findings.

Influence of ER-CR-YSGG Laser and Photodynamic Therapy on the Dentin Bond Integrity of Nano-Hydroxyapatite Containing Resin Dentin Adhesive: SEM-EDX, Micro-Raman, Micro-Tensile, and FTIR Evaluation

The study aimed to analyze the effect of the addition of nano-hydroxyapatite (nano-HA) particles on the mechanical properties of experimental adhesive (EA). Furthermore, dentin interaction of EA (without nano-HA) and EA with nano-HA (hereon referred to as HA-10%) were also investigated and equated. Methods consisting of scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, micro-tensile bond strength (µTBS) test, and Fourier transform infrared (FTIR) spectroscopy were employed to study nano-HA particles shape, dentin bond strength, degree of conversion (DC), and adhesive-dentin interaction. Ninety teeth (N = 90) were collected, and pre-bonding, conditioning of dentin was performed utilizing phosphoric acid (H₃PO₄) etching, photodynamic therapy (PDT), and ER-CR-YSGG (ECY) laser. The teeth were set to form bonded specimens using two adhesives. Nano-HA particles were spherical-shaped, and EDX confirmed the presence of oxygen, calcium, and phosphorus. Micro-Raman spectroscopy revealed distinct phosphate and carbonate peaks for nano-HA. The µTBS test demonstrated highest values for HA-10% group on the H₃PO₄ conditioned dentin. The greatest DC was observed for the EA group. The addition of nano-HA-10 wt.% particles in dentin adhesive resulted in improved bond strength. The incorporation also demonstrated acceptable DC (although lower than EA group), suitable dentin interaction, and resin tag formation.

Influence of Different Conditioning Treatments on the Bond Integrity of Root Dentin to rGO Infiltrated Dentin Adhesive. SEM, EDX, FTIR and MicroRaman Study

The present study aimed to synthesize and equate the mechanical properties and dentin interaction of two adhesives; experimental adhesive (EA) and 5 wt.% reduced graphene oxide rGO) containing adhesive. Scanning electron microscopy (SEM)-Energy-dispersive X-ray spectroscopy (EDX), Micro-Raman spectroscopy, push-out bond strength test, and Fourier Transform Infrared (FTIR) spectroscopy were employed to study nano-bond strength, degree of conversion (DC), and adhesive-dentin interaction. The EA was prepared, and rGO particles were added to produce two adhesive groups, EA-rGO-0% (control) and rGO-5%. The canals of sixty roots were shaped and prepared, and fiber posts were cemented. The specimens were further alienated into groups based on the root canal disinfection technique, including 2.5% sodium hypochlorite (NaOCl), Photodynamic therapy (PDT), and ER-CR-YSGG laser (ECYL). The rGO nanoparticles were flake-shaped, and EDX confirmed the presence of carbon (C). Micro-Raman spectroscopy revealed distinct peaks for graphene. Push-out bond strength test demonstrated highest values for the EA-rGO-0% group after NaOCl and PDT conditioning whereas, rGO-5% showed higher values after ECYL conditioning. EA-rGO-0% presented greater DC than rGO-5% adhesive. The rGO-5% adhesive demonstrated comparable push-out bond strength and rheological properties to the controls. The rGO-5% demonstrated acceptable DC (although lower than control group), appropriate dentin interaction, and resin tag establishment.