Evaluation of Microbiological Susceptibility and Long-term Adhesive Properties to Dentin of Primers with Terminalia catappa Linn.

PURPOSE: To investigate the antibacterial effects of Terminalia catappa Linn (TCL) leaf extracts at different concentrations and the effects of these extracts used as primers on the long-term adhesive properties of two universal adhesives. MATERIALS AND METHODS: After extract preparation, the antimicrobial and antibacterial activities of TCL against Streptococcus mutans (UA 159) were assessed in microdilution assays to provide the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Additionally, to provide quantitative data on the ability of TCL extract to reduce cell viability, colony forming units (CFU) were counted. To examine adhesive properties, 288 human molars were randomly assigned to 32 experimental conditions (n = 9) according to the following variables: (1) treatment agent: negative control (untreated surface), and primers at concentrations of 1xMIC, 5xMIC, and 10xMIC; (2) adhesives: Scotchbond Universal (SBU) and Futurabond Universal (FBU); (3) adhesive strategy: etch-and-rinse (ER) or self-etch (SE); and (4) storage time: 24 h or after 2 years. Primers were applied for 60 s, upon which the teeth were incrementally restored and sectioned into adhesive-dentin bonded sticks. These were tested for microtensile bond strength (µTBS) and nanoleakage (NL) after 24-h and 2-year water storage, as well as in-situ degree of conversion (DC) at 24 h. The chemical profile of the hybrid layer was determined via micro-Raman spectroscopy. Biofilm assay data were analyzed using the Kruskal-Wallis test; the pH of culture media and the chemical profile were analyzed by one-way ANOVA. The adhesive properties (µTBS, NL, DC) were evaluated using a four-way ANOVA and Tukey's test. Significance was set at 5%. RESULTS: Similar values of MIC and MBC were observed (2 mg/ml), showing bactericidal potential. CFU analysis demonstrated that concentrations of 5xMIC and 10xMIC significantly inhibited biofilm formation (p < 0.001). The application of the TCL primer at all concentrations significantly increased the immediate µTBS and DC, and decreased the immediate NL values when compared to the control group (p < 0.05), regardless of the adhesive and adhesive strategies. Despite an increase in the NL values for all groups after 2 years (p > 0.05), in groups where the TCL primer was applied, the µTBS remained constant after 2 years for both adhesives, while a decrease in the µTBS was observed in the control groups (p < 0.05). Usually, 10xMIC showed better results than 1xMIC and 5xMIC (p < 0.05). The application of TCL promoted cross-linking; cross-linking rates increased proportionally to the concentration of TCL (p < 0.05). CONCLUSION: Primers containing TCL promoted bactericidal and bacteriostatic action, as well as cross-linking with dentin, while maintaining the adhesive properties of the adhesive-dentin interface after 2 years of water storage.

Prolonged polymerization of a universal adhesive in non-carious cervical lesions: 36-month double-blind randomized clinical trial.

OBJECTIVE: To evaluate the effect of prolonged (P) polymerization time of a universal adhesive system applied in etch-and-rinse (ER) or self-etch (SE) strategies on the clinical performance of restorations in non-carious cervical lesions (NCCLs), after 36 months of clinical service. METHODS: A total of 140 restorations were randomly placed in 35 subjects according to the polymerization time groups: ER (10 s); ER-P (40 s); SE (10 s); and SE-P (40 s) at 1,200 mW/cm2. Composite resin was placed incrementally. The restorations were evaluated immediately and after 6, 12, 18, and 36 months using the FDI criteria. Data were analyzed using the Kaplan-Meier survival test for retention loss, and the Kruskal-Wallis' test for secondary outcomes (α = 0.05). RESULTS: After 36 months, 19 restorations were lost: ER 6, ER-P 2, SE 9, SE-P 2. The retention rates were 82.3% for ER; 94.1 % for ER-P; 73.5 % for SE; and 94.1 % for SE-P, with a significant difference between ER vs. ER-P and SE vs. SE-P, as well as ER vs. SE-P and ER-P vs. SE (p < 0.0001). Minor defects were observed in 18 restorations for the marginal staining criteria: ER 5, ER-P 2, SE 8, SE-P 3; and in 33 restorations for the marginal adaptation criteria: ER 11, ER-P 4, SE 12, and SE-P 6 (p > 0.05). No restorations showed recurrence of caries or postoperative sensitivity. CONCLUSIONS: A prolonged polymerization time of 40 s improves the clinical performance of the universal adhesive for both adhesive strategies evaluated, even after 36 months. CLINICAL SIGNIFICANCE: Prolonging the polymerization time of a universal adhesive from 10 to 40 s has been shown to improve its clinical performance when used in NCCLs.

Dual-functional etchants that simultaneously demineralize and stabilize dentin render collagen resistant to degradation for resin bonding.

OBJECTIVES: To develop dual-functional etchants that could demineralize and stabilize dentin collagen simultaneously, and to assess the effects of these etchants on collagen crosslinking, biostability and resin bonding properties under clinically relevant conditions. METHODS: Dual-functional etchants were prepared by mixing 56% glycolic acid and 17% phosphoric acid and adding 1% of theaflavins (TF) or proanthocyanidins from grape seed extract (GSE). The etchant without crosslinker was used as control. The prepared human dentin specimens were treated with the 3 etchants for 30 s and analyzed for chemical interaction using Fourier transform infrared spectroscopy and resistance of the demineralized layer to collagenase degradation using electron microscopy (EM). Resin-dentin interfacial bonding properties were evaluated after 24 h and after 10,000 thermocycling through microtensile bond strength (µTBS), nanoleakage and matrix metalloproteinases (MMPs) activity via in situ zymography. Statistical analysis was done using ANOVA and post- hoc Tuckey's test. RESULTS: Compared to control, TF and GSE dual-functional etchants were able to demineralize dentin, induce collagen crosslinking and protect the demineralized layer from collagenase degradation within 30 s. High resolution EM images showed better protection with TF etchant compared to GSE. There was a significant reduction in µTBS and an increase in nanoleakage and MMPs activity in control after thermocycling (p < 0.05) while these changes weren't seen in dual-functional etchants. SIGNIFICANCE: Dual-functional etchants, especially TF containing, provide collagen protection against degradation and result in stable µTBS and less nanoleakage and MMPs activity under clinically relevant conditions.

Effect of Different Crosslinkers on Denatured Dentin Collagen's Biostability, MMP Inhibition and Mechanical Properties.

OBJECTIVE: Sound, natural dentin collagen can be stabilized against enzymatic degradation through exogenous crosslinking treatment for durable bonding; however, the effect on denatured dentin (DD) collagen is unknown. Hence, the ability of different crosslinkers to enhance/restore the properties of DD collagen was assessed. METHODS: Demineralized natural and DD collagen films (7 mm × 7 mm × 7 µm) and beams (0.8 mm × 0.8 mm × 7 mm) were prepared. DD collagen was experimentally produced by heat or acid exposure, which was then assessed by various techniques. All specimens were then treated with 1 wt% of chemical crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/n-hydroxysuccinimide (EDC/NHS) and two structurally different flavonoids-theaflavins (TF) from black tea and type-A proanthocyanidins from cranberry juice (CR) for either 30 s or 1 h. The controls were untreated. Dentin films were assessed for chemical interaction and cross-linking effect by FTIR, biostability against exogenous collagenase by weight loss (WL) and hydroxyproline release (HYP), and endogenous matrix metalloproteinases (MMPs) activity by confocal laser microscopy. Dentin beams were evaluated for tensile properties. Data were analyzed using ANOVA and Tukey's test (α = 0.05). RESULTS: Compared with natural collagen, DD collagen showed pronounced structural changes, altered biostability and decreased mechanical properties, which were then improved to various degrees that were dependent on the crosslinkers used, with EDC/NHS being the least effective. Surprisingly, the well-known MMP inhibitor EDC/NHS showed negligible effect on or even increased MMP activity in DD collagen. As compared with control, cross-linking induced by TF and CR significantly increased collagen biostability (reduced WL and HYP release, p < 0.05), MMP inhibition (p < 0.001) and mechanical properties (p < 0.05), regardless of denaturation. CONCLUSIONS: DD collagen cannot or can only minimally be stabilized via EDC/NHS crosslinking; however, the challenging substrate of DD collagen can be enhanced or restored using the promising flavonoids TF and CR.

48-month clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A double-blind randomised clinical trial.

OBJECTIVES: This study aimed to evaluate the effect of copper nanoparticles (CuNp) on the clinical performance of a universal adhesive system used as an etch-and-rinse or self-etch strategy. METHODS: A total of 216 class V (non-carious lesions) restorations were randomly placed in 36 subjects according to the following groups: ERcu, adhesive in etch-and-rinse with 0.1% CuNp; ERct, adhesive in etch-and-rinse without CuNp; SEcu, adhesive in self-etch with 0.1% CuNp; and Sect, adhesive in self-etch without CuNp. Restorations were evaluated at baseline and at 6, 12, 18, 36, and 48 months, using the FDI and USPHS criteria. Appropriate statistical analyses were performed (α = 0.05). RESULTS: After 48 months, 14 restorations were lost (two for ERcu, five for SEcu, and seven for SEct) and the retention rates (95% confidence interval [CI]) were 74.1% for ERcu (95% CI 61.1-83.8); 81.5% for ERct (95% CI 69.2-89.6); 64.8% (95% CI 51.5-76.2) for SEcu; and 64.8% (95% CI 51.5-76.2) for SEct, with statistical differences between SEct vs. ERct and SEcu vs. ERct (p < 0.05). No significant differences between the groups were observed when the secondary parameters were evaluated (p > 0.05). Nineteen restorations (two for ERcu, two for ERct, six for SEcu, and nine for SEct) showed minor marginal staining, and 44 restorations (7 for ERcu, 8 for ERct, 14 for SEcu, and 15 for SEct) presented minimal marginal adaptation defects. SIGNIFICANCE: This is the first long-term clinical trial to show that the addition of CuNp to a universal adhesive system does not affect clinical performance.

Salivary esterases dramatically reduce biostability of dentin collagen treated with galloylated polyphenols.

OBJECTIVE: To investigate the effects of salivary esterases on biostability of collagen treated by galloylated polyphenols. METHODS: Human dentin was microtomed into 6-µm-thick films, which were demineralized and treated for 60 s using solutions containing 0.6% and 2% of one of the crosslinkers: tannic acid (TAC), epigallocatechin gallate (EGCG), epigallocatechin (EGC), and N-[3-dimethylaminopropyl]-N'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS), and for 1 h using EDC/NHS. Half of the treated and untreated (control) films were subjected to human saliva incubation. Collagen biostability was assessed via exogenous protease biodegradation by weight loss and hydroxyproline release, and endogenous MMPs by in situ zymography. The degradation products of galloylated polyphenols (TAC and EGCG) by saliva were monitored using proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). The esterase activity of saliva induced by the crosslinkers was also assessed. RESULTS: Collagen films treated with TAC and EGCG exhibited significantly improved biostability (p < 0.05); however, the enhanced biostability was severely reduced after saliva incubation (p < 0.001). For EDC/NHS treated collagen, saliva incubation showed negligible effect on the biostability. 1H NMR studies confirmed the esterase-catalyzed hydrolysis of the galloyl. GPC measurements showed decreased molecular weight of TAC in saliva indicating its chemical degradation. Both TAC and EGCG showed much higher esterase activity than other treatment groups. SIGNIFICANCE: The galloyl group plays important role in collagen crosslinking, inducing higher biostability. However, galloylated polyphenols crosslinked on collagen are highly susceptible to metabolism of human saliva by salivary esterase, dramatically compromising the enhanced biostability.

Sonic application of one-step self-etch adhesive in composite restorations of non-carious cervical lesions: A double-blind randomized clinical trial.

OBJECTIVES: To evaluate the influence of the sonic device on the clinical performance of one-step self-etch adhesive systems in non-carious cervical lesions (NCCLs) after 18 months. MATERIALS AND METHODS: Forty patients participated in this study. Eighty restorations were assigned to two groups (n = 40): Sonic application and Manual application. After the adhesive application (iBond Self-Etch, Kulzer, Hanau, Germany), NCCLs were restored using composite resin (Charisma, Kulzer, Hanau, Germany). The restorations were evaluated at baseline and after 18 months both according to the Word Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. Friedman repeated measures analysis of variance by rank and Wilcoxon test for significance in each pair were applied (α = 0.05). RESULTS: After 18 months, 38 patients were evaluated. Twenty-three restorations were lost (19 for manual vs. 4 for sonic application). The retention rates (95% confidence interval) were 50% (CI 34.8%-65.1%) for manual application and 84.2% (CI 69.6%-92.6%) for sonic application (p < 0.05). Twelve restorations showed marginal staining (nine for manual vs. three for sonic application; FDI, p < 0.05) and nine some marginal discrepancy (seven for manual vs. two for sonic application; FDI, p < 0.05). No restorations showed postoperative sensitivity and caries recurrence at the time. CONCLUSION: The sonic application increases the retention rate of iBond Self-Etch after 18 months of clinical evaluation in NCCLs. CLINICAL RELEVANCE: The application of a simplified self-etch adhesive (iBond Self-Etch) associated to a sonic device seems to be an alternative to improve the clinical behavior in NCCLs.

An 18-month clinical evaluation of prolonged polymerization of a universal adhesive in non-carious cervical lesions: A double-blind randomized clinical trial.

OBJECTIVE: This study aimed to evaluate the effect of prolonging polymerization time on the 18 months clinical performance of a universal adhesive system used as etch-and-rinse (ER) and self-etch (SE). METHODS: 140 restorations were randomly placed in 35 subjects according to the following groups: ER10 (light-curing for 10 s); ER40 (light-curing for 40 s); SE10 (light-curing for 10 s) and; SE40 (light-curing for 40 s/1200 mW/cm2). A resin composite was placed incrementally. The restorations were evaluated at baseline and after 18 months by using the FDI criteria. The following outcomes were evaluated: marginal staining, marginal adaptation, spontaneous post-operative sensitivity and recurrence of caries. The differences among the groups were calculated using Friedman repeated measures analysis of variance rank (α = 0.05). RESULTS: After 18 months the retention/fracture rates were 88.9% (95%CI 74.1-95.6%) for ER10, 94.3% (95%CI 91.4-98.5%) for ER40, 77.2% (95%CI 60.1-87.9) for SE10 and 97.2% (95%CI 85.5-99.9%) for SE40. A significant difference was detected in the retention rate when SE10 was compared to the SE40 (p = 0.01). Also, ER40 showed a significant improvement of the marginal adaptation when compared to ER10 (p = 0.01). SIGNIFICANCE: This is the first study that demonstrates an improvement in the clinical performance of universal adhesive systems in non-carious cervical lesions when prolonged light-cured was applied.

Distinct effects of polyphenols and solvents on dentin collagen crosslinking interactions and biostability.

OBJECTIVE: To evaluate the effects of different polyphenols and solvents on dentin collagen's crosslinking interactions and biostabilization against MMPs and collagenase degradation. METHODS: Two polyphenols [proanthocyanidin (PA) and quercetin (QC)] with different water solubility were prepared as treatment solutions using ethanol (EtOH) or dimethyl sulfoxide (DMSO) as solvents. 6-um-thick dentin films were microtomed from dentin slabs of third molars. Following demineralization, films or slabs were subject to 60-s treatment (PA or QC) or no treatment (control) with subsequent extended-rinse with original solvent (EtOH or DMSO) or distilled water (DW). Collagen crosslinking interactions were assessed by FTIR. Biostability was assessed through endogenous MMPs activity via confocal laser scanning microscopy, and exogenous collagenase degradation via weight loss, hydroxyproline release and SEM. Finally, direct collagenase inactivation was also evaluated. Data were analyzed by three-way ANOVA and post-hoc tests (α=0.05%). RESULTS: Distinct effects of two polyphenols and solvents on collagen crosslinking and biostabilization were observed. Higher crosslinking and biostability efficacy occurred with PA than QC (p<0.001) that demonstrated negligible collagen interactions. With DMSO solvent, efficacy results were significantly reduced with both polyphenols (p<0.05). DMSO-rinse further weakened interactions of PA with collagen, diminishing biostability (p<0.05). Low biostability was detected with QC and DW-rinse, suggesting direct enzymatic inhibition due to physical presence in collagen. SIGNIFICANCE: Collagen crosslinking interactions and biostability depend on polyphenol chemical characteristics. Treatment-solution solvents may affect interactions between polyphenols and collagen, specifically, DMSO showed detrimental effects on collagen crosslinking and biostability and should be used with caution.

Cranberry Juice Extract Rapidly Protects Demineralized Dentin against Digestion and Inhibits Its Gelatinolytic Activity.

Improving the longevity of composite restorations has proven to be difficult when they are bonded to dentin. Dentin demineralization leaves collagen fibrils susceptible to enzymatic digestion, which causes breakdown of the resin-dentin interface. Therefore, measures for counteracting the enzymatic environment by enhancing dentin collagen's resistance to degradation have the potential to improve the durability of dental composite restorations. This study aimed to evaluate the effects of polyphenol-rich extracts and a chemical cross-linker on the cross-linking interaction, resistance to digestion, and endogenous matrix metalloproteinase (MMP) activities of dentin collagen under clinically relevant conditions. Ten-µm-thick films were cut from dentin slabs of non-carious extracted human third molars. Following demineralization, polyphenol-rich extracts-including grape seed (GSE), green tea (GTE), and cranberry juice (CJE)-or chemical cross-linker carbodiimide with n-hydroxysuccinimide (EDC/NHS) were applied to the demineralized dentin surfaces for 30 s. The collagen cross-linking, bio-stabilization, and gelatinolytic activities of MMPs 2 and 9 were studied by using Fourier-transform infrared spectroscopy, weight loss, hydroxyproline release, scanning/transmission electron microscopy, and in situ zymography. All treatments significantly increased resistance to collagenase degradation and reduced the gelatinolytic MMP activity of dentin collagen compared to the untreated control. The CJE- and GSE-treated groups were more resistant to digestion than the GTE- or EDC/NHS-treated ones (p < 0.05), which was consistent with the cross-linking interaction found with FTIR and the in situ performance on the acid-etched dentin surface found with SEM/TEM. The collagen films treated with CJE showed the lowest MMP activity, followed by GSE, GTE, and, finally, EDC/NHS. The CJE-treated dentin collagen rapidly increased its resistance to digestion and MMP inhibition. An application of CJE as short as 30 s may be a clinically feasible approach to improving the longevity of dentin bonding in composite restorations.

The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites.

BACKGROUND: To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. MATERIAL AND METHODS: Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Crios (BC; n=60) which were randomly separated into six subgroups (n=10) according to the surface treatment: control (CTL); sandblasting (SB); sandblasting and silane (SBSL); hydrofluoric acid (HF); hydrofluoric acid and silane (HFSL); and Monobond Etch&Prime (MEP). The mandibular central incisor metal brackets were bonded with a light-cure adhesive. The SBS data were analyzed using the two-way analysis of variance and Turkey's test, while the adhesive remnant index (ARI) by the Kruskal-Wallis, all the significance was set at 5%. RESULTS: A higher SBS was found for BC in comparison with LU (p< 0.05). All the surface treatments increased the SBS in comparison with CTL (p< 0.0001). Treatment with HF, SBSL and HFSL (p> 0.05) showed a higher SBS, which was followed by MEP and SB (p> 0.05), all in comparison with CTL (p< 0.0001). For ARI, a significant effect was detected only for the surface treatment (p< 0.01), and not for CAD/CAM resin (p> 0.05). Significant differences were detected between CTL to HF, and HF to MEP, as well. CONCLUSIONS: The SBS is highly affected by the surface treatment and also by the CAD/CAM composite. The surface treatment improves the SBS and should be encouraged when orthodontic brackets are bonded to CAD/CAM composites. Key words:CAD/CAM composite resin, brackets, shear bond strength, surface treatment, bonding.

Methacrylate-functionalized proanthocyanidins as novel polymerizable collagen cross-linkers - Part 1: Efficacy in dentin collagen bio-stabilization and cross-linking.

OBJECTIVE: The aim of the study was to investigate the effects of methacrylate-functionalized proanthocyanidins (MAPAs) on dentin collagen's bio-stabilization against enzymatic degradation and crosslinking capability. METHODS: Three MAPAs were synthesized via varying methacrylate (MA) to proanthocyanidins (PA) feeding ratios of 1:2, 1:1, and 2:1 to obtain MAPA-1, MAPA-2, and MAPA-3, respectively. The three MAPAs were structurally characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FTIR) spectroscopic methods. 5-µm-thick dentin films were microtomed from dentin slabs of third molars. Following demineralization, films or slabs were treated with 1% MAPAs or PA in ethanol for 30 s. Collagen bio-stabilization against enzymatic degradation was analyzed by weight loss (WL) and hydroxyproline release (HYP) of films, as well as scanning electron microscopy (SEM) on dentin slabs. Crosslinking capacity and interactions of MAPAs with collagen were investigated by FTIR. Data were analyzed by ANOVA and Tukey's test (α = 0.05%). RESULTS: MA:PA feeding ratios affected MAPAs' chemical structures which in turn led to different collagen stabilization efficacy against degradation and varied collagen crosslinking capabilities. Higher collagen stabilization efficacy was detected using MAPA-1 (WL 10.52%; HYP 13.53 µg/mg) and MAPA-2 (WL 5.99%; HYP 11.02 µg/mg), which was comparable to that using PA (WL 8.79%; HYP 13.17 µg/mg) (p > 0.05), while a lower collagen stability occurred in MAPA-3 (WL 38.48%; HYP 29.49 µg/mg), indicating excessive MA-functionalization would compromise its stabilization efficacy. In comparison, complete digestion was detected for untreated collagen (WL 100%; HYP 102.76 µg/mg). The above results were consistent with collagen crosslinking efficacy of the three MAPAs revealed by SEM and FTIR. SIGNIFICANCE: A new class of novel polymerizable collagen cross-linkers MAPAs was synthesized and shown that, when appropriate MA:PA ratios were applied, the resulting MAPAs could render high collagen stability and the ability to copolymerize with resin monomers, overcoming the drawbacks of PA. These new polymerizable crosslinkers, when included in adhesives, could lead to long-lasting dentin bonding.

Methacrylate-functionalized proanthocyanidins as novel polymerizable collagen cross-linkers - Part 2: Effects on polymerization, microhardness and leaching of adhesives.

OBJECTIVE: The aim of the study was to investigate the effects of a novel polymerizable collagen cross-linker methacrylate-functionalized proanthocyanidins (MAPA) on the polymerization, microhardness and leaching of a HEMA-based experimental dental adhesive system. METHODS: Three MAPAs were synthesized using different methacrylate (MA) to proanthocyanidins (PA) feeding ratios of 1:2, 1:1, and 2:1 to obtain MAPA-1, MAPA-2, and MAPA-3, respectively. The resulting three MAPAs and PA were added to an experimental adhesive formulated with HEMA and a tri-component photoinitiator system (0.5 wt% CQ/EDMAB/DPIHP) at 1%, 5% and 10% MAPA or PA concentrations (wt%). The adhesive polymerization kinetics was measured continuously in real-time for 10 min using a Fourier-transform infrared spectroscopy (FTIR) with an attenuated total reflectance (ATR) accessory. Degree of conversion (DC) and Vickers microhardness (MH) of cured adhesives were measured at 72 h post-cure. The leaching of cured adhesives in DI water was monitored using UV-vis spectrophotometer. Statistical analysis was performed using one-way and two-way ANOVA, Tukey's (p < 0.05). RESULTS: The adhesive formulations with 1%, 5% and 10% MAPAs-1, -2, -3 all generated higher rate of polymerization and 10-min DC than the formulations with PA at the same concentrations. At 72 h post-cure, the adhesive formulation with 5% MAPA-2 exhibited significantly higher DC (99.40%) and more than doubled MH (18.93) values than the formulation with 5% PA (DC = 89.47%, MH = 8.41) and the control (DC = 95.46%, MH = 9.33). Moreover, the cured adhesive with 5% MAPA-2 demonstrated significantly reduced PA leaching in comparison with cured adhesive with 5% PA. SIGNIFICANCE: Synthesized MAPA is a novel class of polymerizable collagen cross-linker that not only stabilizes dentin collagen via its PA component, but also improves polymerization, mechanical properties and stability of HEMA-based adhesives via its MA component. By inheriting the benefit while overcoming the drawback of PA, MAPA offers a revolutionary solution for improved bond-strength and longevity of dental restorations.

A novel carbamide peroxide polymeric nanoparticle bleaching gel: Color change and hydrogen peroxide penetration inside the pulp cavity.

OBJECTIVE: This study evaluated the hydrogen peroxide (HP) penetration inside the pulp cavity and the color change of teeth submitted to the 15% carbamide peroxide (CP) nanoparticle bleaching gel at several application times. MATERIALS AND METHODS: Premolars were divided into nine groups (n = 6) according to 15% CP bleaching agents (nanoparticle and commercial) and to application times (15, 30, 45, and 60 minutes). A negative control was exposed to ultra-purified water. After a whitening procedure, the HP concentration (µg/mL) inside the pulp cavity was assessed via spectrophotometry. The color change (ΔE* and ΔE00*) was evaluated with a spectrophotometer. Data were analyzed via two-way ANOVA and Tukey (α = 0.05). RESULTS: A lower concentration of HP was detected for CP nanoparticle gel after 30 and 45 minutes of whitening procedure (P = .001). The bleaching groups promoted a higher color change (ΔE* and ΔE00*) regardless of the application time (P = .0001). CONCLUSIONS: The CP nanoparticle gel reduced HP inside the pulp cavity, and showed effective bleaching compared with CP commercial gel. CLINICAL SIGNIFICANCE: Using 15% carbamide peroxide nanoparticle bleaching gel decreased the HP penetration inside the pulp cavity and may decrease bleaching-induced tooth sensitivity in at-home bleaching.

Is it possible for a simultaneous biomodification during acid etching on naturally caries-affected dentin bonding?

OBJECTIVES: This study investigated the ability of modified phosphoric acids containing chlorhexidine (CHX) or grape seed extract (GSE) for promoting simultaneous biomodification during acid etching on bonding properties in caries-affected dentin (CAD). MATERIALS AND METHODS: Thirty-two human molars (8 with sound dentin [SD] and 24 naturally CAD) were selected for the study. The SD and CAD were initially exposed, then randomized and etched according to the following groups: (1) SD (SD-CT) and CAD (CAD-CT) both with 37% phosphoric acid, (2) CAD with 2% CHX containing 37% phosphoric acid (CAD-CHX), and (3) CAD with 2% GSE containing 10% phosphoric acid (CAD-GSE). The bonding procedure and composite build-ups were performed after acid etching. Subsequently, they were sectioned in resin-dentin specimens. The specimens were submitted for chemical profiling by micro-Raman, microtensile bond strength (µTBS), failure mode with chemical characterization by FEG/SEM-EDX, and in situ zymography by CLSM. The data from µTBS and CLSM were statistically analyzed (1-way ANOVA and Tukey's test; α = 0.05). RESULTS: The highest µTBS results were shown for SD-CT in comparison with all CAD groups (p < 0.001), and the lowest for CAD-CT and CAD-CHX (p < 0.001). The etching with CHX did not increase the µTBS for CAD when compared with CT (p = 0.52). However, the etching with GSE improved significantly the µTBS for CAD when compared with CT and CHX (p < 0.001). The chemical profile detected chemical and structural changes in collagen peaks for CAD-CT, which were not detected when the CAD was etched by modified acids. Also, the poorest hybridization ability was detected in CAD for CT, which was significantly improved with modified acids, especially the GSE, as evaluated by chemical profile and failure mode. A significant reduction of MMP activity on CAD was promoted by modified acids in comparison with CT (both p < 0.001). CONCLUSIONS: The GSE-containing acid was able to promote biomodification during the acid etching, increasing the bonding properties and reducing the activity of the MMPs within the hybrid layer. CLINICAL RELEVANCE: The use of GSE-containing phosphoric acid can be a promising alternative to improve the bonding performance on caries-affected dentin, since it is capable of biomodifying the dentin during the acid etching, without adding any extra step in bonding procedures.

Five-year clinical evaluation of a universal adhesive: A randomized double-blind trial.

OBJECTIVE: To evaluate the five-year clinical performance of Scotchbond Universal Adhesive (SU; 3M Oral Care, St. Paul, MN, USA) in non-carious cervical lesions (NCCLs) using two evaluation criteria. METHODS: Thirty-nine patients participated in this study. Two hundred restorations were assigned to four groups: SU-ERm: etch-and-rinse + moist dentin; SU-ERd: etch-and-rinse + dry dentin; SU-Set: selective enamel etching; and SU-SE: self-etch. A nanofilled composite resin was placed incrementally. The restorations were evaluated at baseline and after 5 years using both the World Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. The survival rates (retention/fractures) were calculated with the Kaplan-Meier and the log-rank test. For the secondary outcomes, Friedman repeated measures analysis of variance by rank was applied (α = 0.05). RESULTS: After 5 years the recall rate was 86%. The retention/fracture rates were 93% for Erm and ERd, 88.4% for SEet and 81.4% for SE. A significant difference was observed for SE vs. ERd and SE vs. ERm (p = 0.01). Also, marginal discoloration and adaptation showed significant differences with ERm and ERd resulting in fewer marginal discrepancies than SE (p < 0.05). SIGNIFICANCE: After 5 years, the clinical behavior of the universal adhesive in the etch-and-rinse strategy was better when compared to the self-etch strategy. The use of selective enamel etching is highly recommended for the self-etch strategy. The FDI and USPHS evaluation criteria showed similar results after 5 years.

Standardized Arrabidaea chica Extract Shows Cytoprotective Effects in Zoledronic Acid-Treated Fibroblasts and Osteoblasts.

INTRODUCTION: Osteonecrosis of the jaw is a condition associated with intraoral ulceration and bone necrosis induced by antiresorptive medications, such as zoledronic acid, a bisphosphonate. Previous data on Arrabidaea chica (H&B.) Verlot wound healing activity prompted the study reported herein on A. chica standardized hydro alcoholic extract in vitro cytoprotective activity data on epithelial and osteoblastic cells exposed to zoledronic acid (ZA). METHODS: Primary human gingival fibroblasts and murine pre-osteoblasts were treated with ZA 10 µM together with 5 or 10 µg.mL-1 A. chica extract for 24h and 48 h. At both times, cells were submitted to viability assay and caspase 3/7 activation evaluation. Statistical analysis used one-way ANOVA and p=0.05. RESULTS: In cell viability assay, a drastic damage effect of ZA appeared after 48 h in both epithelial (55.8%) and pre-osteoblastic cells (39.7%). When treated with ZA in combination with A. chica extract, cells showed higher viability values: 74.1%-82.3% for fibroblasts and 66% for pre-osteoblasts. Furthermore, the combined treatment presented lower caspase 3/7 activation in fibroblasts and pre-osteoblasts. CONCLUSION: At low concentrations, A. chica extract showed promising cytoprotective effects against ZA-induced damage actions; however, further in vitro and in vivo studies are required to establish the mechanism of action.

Chlorhexidine preserves the hybrid layer in vitro after 10-years aging.

OBJECTIVE: The present study investigated the ability of a chlorhexidine (CHX)-containing primer (0.2% aqueous solution) to inhibit dentinal enzymes, preserve the hybrid layer (HL) and remain within the HL, after 10 years of aging in artificial saliva at 37°C. METHODS: Non-carious extracted molars were assigned to two groups, cut into slabs exposing middle/deep dentin, etched and bonded with Adper Scotchbond 1XT (SB1XT) with or without 0.2% CHX aqueous solution pretreatment. Composite build-ups were made, and the specimens were cut in 1-mm thick bonded sticks. In situ zymography was performed on freshly prepared specimens (T0) and specimens aged for 10 years (T10-yr) at 37°C in artificial saliva, to investigate endogenous gelatinolytic activity within the HL. At T10-yr, specimens were also decalcified and embedded in epoxy resin for TEM analysis. Micro-Raman spectroscopy was performed at T0 and T10-yr to evaluate the chemical profiles in intertubular dentin and the HL. RESULTS: In situ zymography showed less pronounced enzymatic activity in the CHX-pretreated group (p<0.05) regardless of aging, maintaining a similar level of fluorescence at T0 and T10-yr (p>0.05). TEM results showed that 98% of the HL had been degraded in the control group, while 95% of the HL was intact in the experimental group. Moreover, all the Raman spectra peaks assigned to CHX could be identified only in the CHX-pretreated group (T0 and T10-yr). SIGNIFICANCE: In vitro, CHX remains in the HL after 10 years with its inhibitory effect preserved. This may be the underlying factor for HL preservation after this long aging period.

Improving bonding to eroded dentin by using collagen cross-linking agents: 2 years of water storage.

OBJECTIVES: The aim of this study was to investigate the effects of collagen cross-linking agents on nanomechanical and bonding properties of eroded dentin (ED), 24 h and 2 years after water storage. MATERIALS AND METHODS: Human molar dentin surfaces, eroded by soft drinks or citric acid, were acid-etched and treated with primers containing proanthocyanidin (PA) and riboflavin (RI) or were untreated (control) and tested after 24 h and 2 years. After acid etching and adhesive application (Prime&Bond Elect (PBE); Scotchbond Universal (SBU); Tetric n-bond Universal (TEU)), specimens were sectioned into beams and tested for microtensile bond strength (µTBS) and silver nitrate deposition (NL) after 24 h and 2 years. The beams were used to evaluate the 24-h in situ conversion of degree (DC). Nanohardness (NH) and Young's modulus (YM) were evaluated via resin-bonded dentin slices after 24 h and 2 years. A three-way ANOVA and Tukey's test were used for statistical analysis (5%). RESULTS: For both storage times, ED with citric acid resulted in lower µTBS, NH, and YM and higher NL for each adhesive system than soft drink ED (p < 0.05). After 2 years of water storage, cross-linking primers maintained the µTBS, NH, and YM (p < 0.05) when compared with the control group. Althougth, the NL values decreased for all groups after 2 years of water storage, PA and RI treatments showed NI values lower than control group (p < 0.001). No significant differences were observed between PA and RI treatments (p > 0.05). Cross-linking primers maintain or improve DC (p < 0.03). In general, TEU and SBU yielded higher µTBS, DC, NH, and YM and lower NL than PBE. CONCLUSION: Cross-linking agents improved the results and maintained the resin-ED interface bonding and nanomechanical properties, without jeopardizing adhesive polymerization. CLINICAL RELEVANCE: Cross-linking agents are a viable alternative for improving and maintaining resin-ED interface bonding and nanomechanical properties.

Effect of whitening mouthrinses on bulk-fill composites.

PURPOSE: To evaluate the effect of whitening mouthrinses on sorption (SP) and solubility (SL), percentage of microhardness change (%M), loss of surface (LS), and color change (ΔE) in bulk-fill composites when compared with conventional composites. METHODS: Three bulk-fill composites, Surefil SDR (SF), Filtek Bulk-Fill (BF), and Filtek Bulk-Fill Flow (BFF), and one conventional resin, Filtek Z350 (FZ), were selected. Eighteen samples of each composite were subdivided into three groups based on the type of treatment: Listerine Whitening mouthrinse (LW), Colgate Plax Whitening mouthrinse (CP), and distilled water (DW; control). The samples were prepared according to ISO 4049:2009. Color, roughness, and microhardness were evaluated before and after treatment, while SP and SL values were measured after treatment. The surface morphology of the specimen was examined using scanning electron microscopy. Data were analyzed using two-way ANOVA and Tukey's test. RESULTS: FZ presented significantly lower ΔE when immersed in DW. Additionally, LS was lowest in FZ when compared with the other resins. SF and BFF demonstrated high %M. SL was significantly higher in SF, whereas SP was lowest in BFF after CP treatment. No significant alterations in surface morphology were noted in the BF composites. The BF composites showed a decrease in their properties after immersion in the two types of mouthrinses or in DW, without alterations in the surface morphology. CLINICAL SIGNIFICANCE: Flowable bulk-fill composites showed the greatest changes in their properties when exposed to different mouthrinses or water. Thus, they should be used with caution in areas that will stay exposed to the oral cavity.