This study aimed to evaluate effects of calcium carbonate (CaCO3) and anhydrous strontium carbonate polyelectrolyte-cation complexes on dentin adhesive bonding, mechanical properties and intrafibrillar mineralization of dentinal collagen fibers. Dentin discs were prepared from collected human premolars and treated with 1%SrF₂CaCO3, 0.5%SrF₂CaCO3, 2% SrF₂CaCO3 and distilled water for 15 days under controlled pH. Raman spectroscopy, transmission and scanning electron microscopy were performed to evaluate intrafibrillar mineralization and topographical changes. Diffusional coefficient and density functional theory were calculated. Resin-dentin bond specimens were prepared and microtensile bond strength was measured. Statistical analysis was performed using a one-way ANOVA with subsequent post-hoc comparisons, with significance of p < 0.05. Raman spectroscopy demonstrated a concentration-dependent increase in dentin mineralization, with enhanced phosphate and organic matrix signatures following SrF₂CaCO3 treatment. TEM and HRTEM confirmed organised intra- and extrafibrillar hydroxyapatite deposition, particularly in the 2% SrF₂CaCO3 group, showing aligned crystallites along the collagen axis and well-defined D-periodicity. SEM revealed progressive crystal elongation and surface densification with increasing concentration. Diffusion analysis indicated higher ionic mobility in modified groups, supported by DFT calculations showing increased Ca and P occupancy and crystallographic stability. µ-tensile testing demonstrated significantly improved bond strength in the 1% SrF₂CaCO3 and 2% SrF₂CaCO3 groups without compromising adhesive performance. The present study demonstrated the modification of dentinal surface using a range of concentrations of SrF₂CaCO3 as a multifunctional modifier indicating favourable bond strength and extensive crystallisation capability. The 2% SrF₂CaCO3 polyelectrolyte formulation has a significant potential for clinical application and offers a novel potential solution to address significant challenges in adhesive dentistry. Strontium/fluoride/calcium carbonate polyelectrolyte complexes promote biomimetic dentin remineralization, enhance crystal organisation, and improve resin-dentin bond strength. This strategy offers a biologically guided approach to reinforce compromised dentin, potentially increasing the longevity and reliability of adhesive restorative procedures.

Interfacial and mechanical effects of methylglyoxal on etched dentin: An in vitro study.

This study aimed to assess the effect of incorporating sodium fluoride (NaF) into an adhesive system on the microtensile bond strength of ceramic occlusal veneers. Eighty resin-dentin sticks (~ 1 mm2) were obtained from 20 upper first premolars, with each tooth yielding four sticks. The teeth were sectioned using an Isomet saw to expose deep dentin, and Vita Enamic occlusal veneers were fabricated and cemented prior to sectioning. The specimens (n = 20) were assigned to two adhesive groups: a control (unmodified adhesive) group and a NaF-containing adhesive group. Each group was further subdivided into two subgroups, which were tested after 24h and 6months of storage in artificial saliva at 37°C. Microtensile bond strength was measured using a universal testing machine. Repeated-measures ANOVA revealed no significant effect of adhesive type or storage duration on tensile bond strength. Independent t test showed a highly significant difference between subgroups I-B and II-B, with no significant differences in other comparisons. Mixed failures predominated across all groups, indicating balanced interfacial and cohesive properties, and EDX confirmed successful fluoride incorporation. Incorporation of sodium fluoride into the adhesive system did not alter immediate dentin bond strength but reduced long-term durability of ceramic partial-coverage restorations.

Effect of incorporation of tricalcium silicate to a universal adhesive on microtensile bond strength to dentin and micromorphological patterns of tooth/restoration interface.

This study aimed to assess the outcomes of bromelain enzyme and chlorhexidine (CHX) following endodontic irrigation by evaluating coronal dentin microtensile bond strength (μTBS) and radicular dentin sealer penetration depth. Fifty-one human molars with flat mid-dentin surfaces were soaked in sodium hypochlorite, then randomly assigned to three groups relying on the biomodification approach (n = 17): group 1, saline; group 2, 8% bromelain; and group 3, 2% CHX. After bonding and resin composite build-ups, the μTBS, failure mode, and bond interface were evaluated. Forty-two root canals of human molars were mechanically prepared and randomly distributed among three groups (n = 14), similar to the coronal-dentin biomodification protocol. The sealer-penetration depth was measured utilizing the scanning electron microscope. One- and two-way analyses of variance and the pairwise t- and chi-square tests were utilized. The bromelain group showed the highest statistically significant resin-dentin μTBS values, followed by the CHX and control groups. For sealer-penetration assessment, the bromelain group showed the highest penetration at the middle and apical root levels, whereas CHX demonstrated the highest penetration at the coronal level. Bromelain biomodification positively influenced the resin-dentin bond strength and the sealer-penetration depth in apical and middle levels.

Achieving durable adhesion of composite-resins to dentin remains a key challenge in restorative dentistry, highlighting the need for biomodification strategies. Therefore, this umbrella review aims to systematically overview dentin biomodifiers and evaluate their influence on the durability of composite-resin restorations. Literature search was conducted in PubMed, Scopus, and Web of Science up to October 2024, focusing on three concepts: dentin, biomodification, and bond strength (PROSPERO: CRD42024588804). The corrected covered area (CCA) was calculated to evaluate overlap among the included systematic reviews (SRs). Among 486 identified papers, 9 SRs were selected including 7 meta-analyses. Twenty biomodification agents were identified and classified into natural, physical and chemical agents. These agents were assessed in 51 different setups with micro-tensile bond strength used in 68.62% of them. Timing of bond strength assessments varied from immediate to a 36-months period. As natural agents, Grape Seed Extract and chitosan improved bond strength after long-term aging, while induced riboflavin improved the short and medium-term periods only. Among all categories, the most studied biomodifier was Non-Thermal Atmospheric Plasma, a physical agent, which consistently enhanced resin-dentin bonding over time. However, chemical approaches did not show promising bond strength results at some exceptions. Sodium hypochlorite (NaOCl) and hypochlorous acid both immediately decreased bond strength. Overlap among reviews was slight (CCA = 1.52 %). Various biomodifiers show promise for enhancing adhesion and durability of composite-resin restorations, with their combinations potentially offering synergistic effects. Systematically identifying and characterizing dentin biomodifiers within their limitations lays the groundwork for evidence-based frameworks that guide dentists and shape future research. At present, physical scrubbing and air abrasion are the only readily available dentin biomodification techniques. Riboflavin and chitosan show promise as effective natural and affordable agents; however, their clinical use needs regulatory approval. In contrast, NaOCl should be avoided as it compromises composite restoration's durability.

Advanced biomechanics and stability of the resin-dentin complex via modular A- and B-type proanthocyanidins.

This study evaluated the antibacterial effect of an experimental adhesive system containing kaempferol and its dentin bond strength. The etch-and-rinse adhesive system was manipulated and kaempferol was incorporated at the following concentrations: without KA, 1%, 2% and 4% (K0, K1%, K2%, and K4%). The antibacterial effects of the adhesive system were assessed by the planktonic cell count (n = 5) and metabolic activity of theS. mutansbiofilm using MTT reduction. Demineralization inhibition was evaluated through Knoop hardness at the enamel margin before and after exposure to theS. mutansbiofilm (n = 5). Additionally, microtensile bond strength (μTBS) was measured using a microtensile test (n = 6), and the degree of conversion (DC%) was assessed using FT-IR spectroscopy (n = 5). Results indicated that the planktonic cell count was lower for K4% and K2% than the K0, which did not differ from K1%. K4%, K2%, and K1% exhibited lower biofilm metabolic activity than K0. Furthermore, these groups showed less loss of hardness at restoration margins than K0. Similar results of μTBS were found for all groups (26.86-31.23MPa). The DC% for K1% and K2% was similar to K0, while K4% demonstrated a significantly higher DC% than K0 and K1%, but no difference from K2%. In conclusion, adhesive systems with kaempferol had an antibacterial effect and prevented the enamel demineralization, without jeopardizing μTBS and DC%.

The aim of this in vitro study was to measure the microtensile bond strength (μTBS) and the contact angle of a universal adhesive (Prime & Bond Active) to overdried and water-contaminated human dentin. After exposing flat dentin surfaces (5×5 mm2) of 60 caries- and restoration-free molars, test groups were either overdried or water-contaminated before adhesive application (self-etch) or after phosphoric acid etching (etch&rinse). In control groups, the adhesive was applied according to the manufacturer's instructions. μTBS (n = 45 samples) was analyzed (24 h/thermocycling: 15,000 cycles, 5/55°C). Fracture patterns were assessed microscopically. Contact angles were measured using the sessile drop method. Statistical analysis was performed using Tobit regression and Scheffé correction for bond strength data and Kruskal-Wallis test for contact angle measurements (α = 0.05). Overall, µTBS was significantly higher after etch&rinse application compared to the self-etch mode before (P 0.001, Δ 11.04 MPa) and after aging (P 0.001, Δ 6.73 MPa). The highest μTBS (29.9 ± 10.4 MPa) was achieved by the etch&rinse control before aging. For etch&rinse application, water contamination and overdrying initially led to significantly lower µTBS compared to the control (P = 0.014/P = 0.007). Aging significantly decreased μTBS in both etch&rinse control and overdry groups (P 0.001/P = 0.036). Fracture modes were predominantly adhesive (90%). Contact angle on water-contaminated dentin was significantly lower for self-etch than for etch&rinse mode (P = 0.008). The adhesive application mode significantly influenced bond strength. Dentin surface condition initially affected the µTBS solely in etch&rinse mode. Only on water-contaminated dentin, the contact angle was influenced by the adhesive application mode.

The enzymatic degradation of the hybrid layer by endogenous matrix metalloproteinases (MMPs) represents the major cause of resin-dentin bond strength deterioration. The current study assessed the influence of dentin pre-bonding treatment with alendronate, an MMP inhibitor, on the efficacy of a universal adhesive.Ninety-six extracted molars were randomly allocated into four groups (n = 24) based on dentin surface treatment: no treatment (control), 2 wt% chlorhexidine, 0.03 wt% alendronate, and 0.3 wt% alendronate. Each group was further classified into two sub-divisions (n = 12) according to the adhesive application mode: etch-and-rinse (ER) and self-etch (SE). On flat dentin surfaces, the treatment solution was applied, followed by application of universal adhesive (All Bond UNIVERSAL, BISCO) and composite buildup. Eighty teeth were used for the assessment of microtensile bond strength (µTBS), failure mode, and nanoleakage, while the remaining sixteen teeth were examined using scanning electron microscopy (SEM) to assess the bonded interface. All tests were conducted at 2 time intervals; after 24h and after aging for 5000 thermocycles. Statistical analysis of the µTBS data was performed using three-way ANOVA followed by Tukey's post hoc test. The 0.3 wt% alendronate-treated ER group exhibited the highest µTBS values under both immediate and aged conditions (p value < 0.05). Using SE adhesive mode, the same treatment showed relatively higher µTBS values; however, the variations among SE groups were not significant. Failure mode analysis revealed that immediate alendronate-treated ER groups predominantly exhibited cohesive failures, whereas the ER control group presented a higher frequency of mixed failures. Following thermocycling, alendronate-treated ER groups showed a shift toward mixed failure mode. Nanoleakage analysis indicated greater silver uptake in the ER groups compared to SE groups, particularly after aging. Micromorphological surface analysis by SEM showed that the 0.3 wt% alendronate-treated ER group exhibited the most pronounced resin penetration. It has been concluded that dentin treatment with alendronate specifically 0.3 wt%, before bonding, appeared to enhance bond strength, particularly with etch-and-rinse mode. The results of failure mode analysis, nanoleakage evaluation and micromorphological interface observations confirmed these findings.

The effect of microstructural, compositional, and rheology-based properties of universal adhesive systems on bond strength.

This study evaluated the incorporation of epigallocatechin-3-gallate (EGCG)-loaded poly(lactide-co-glycolide) (PLGA) microparticles into a two-step etch-and-rinse adhesive and their effects on physicochemical properties and EGCG release. EGCG was added to Single Bond 2 either directly (0.01% and 0.1% w/w) or encapsulated in PLGA 50:50 or 75:25 microparticles (0.5%-2% w/w). Cumulative release was measured by UV-Vis spectrophotometry. Degree of conversion (DC) was analyzed by Fourier transform infrared spectroscopy; flexural strength and elastic modulus (E) were tested in three-point bending; and water sorption (WS) and solubility (SL) were evaluated following ISO standards (n=10). Microtensile bond strength (TBS) was tested after 24h, 6, and 12 months. Data were analyzed by anova with significance set at p<0.05. PLGA 50:50/EGCG at 1% showed the highest release, reaching 77.30µg. No significant differences were found in DC, E, WS, and SL among the groups. Bond strengths remained stable in all experimental groups after 6 and 12 months, except for the control. Incorporating 1% EGCG-loaded PLGA 50:50 microparticles into Single Bond 2 may represent a promising strategy for controlled release without compromising physicochemical or mechanical properties.

To evaluate the impact of incorporating chitosan/hydroxyapatite composite nanoparticles (CT/HAP NPs) into a universal adhesive on its bonding effectiveness to caries-affected dentin (CAD) and its in vitro bioactivity. CT/HAP NPs (50:50 by weight) were synthesized via a one-step co-precipitation method. All-Bond universal adhesive was modified with either 0.5 wt% or 1 wt% CT/HAP NPs, yielding three groups: unmodified control, 0.5 wt%, and 1 wt% CT/HAP. Forty-eight molar teeth (4 teeth per group) were used to prepare 240 bonded beams using either etch-and-rinse (ER) or selective-etch (SE) mode (n = 20 bonded beams per group). Micro-tensile bond strength (µTBS) test was conducted using a universal testing machine after 24 h and 6 months of storage in simulated body fluid (SBF). Fifteen adhesive discs (5 mm x 1 mm) (n = 5) were examined using an environmental scanning electron microscope combined with an energy-dispersive X-ray spectroscopy (ESEM/EDX) following storage in SBF for 1 day and 28 days to assess bioactivity and Ca/P ratio. Wettability, pH, and degree of conversion (DC) were assessed using a digital light microscope, a pH meter, and Fourier transform infrared (FTIR) spectroscopy, respectively. µTBS and wettability data were investigated utilizing multilevel ANOVA, while pH and DC were evaluated utilizing one-way ANOVA; Tukey’s post hoc test was applied for pairwise multiple comparisons. The significance level was set at (p < 0.05). The 1 wt% CT/HAP group exhibited significantly higher µTBS at 24 h (ER: 37.50 ± 6.90 MPa; SE: 32.52 ± 6.61 MPa) and at 6 months (ER: 41.81 ± 7.64 MPa; SE: 42.10 ± 7.23 MPa) than the 0.5 wt% CT/HAP and control groups. Adhesives containing CT/HAP NPs showed improved surface mineral deposition and higher Ca/P ratios compared to control. Wettability, pH, and degree of conversion revealed no significant changes. Incorporating chitosan/hydroxyapatite composite nanoparticles into an ultra-mild universal adhesive enhanced its bonding efficacy to caries-affected dentin as well as its bioactive potential, without jeopardizing the physical and chemical properties of the adhesive.

The microtensile bond strength (μTBS) test is the gold standard for evaluating adhesive performance in restorative dentistry. However, the conventional non-trimming technique-referred to in this study as the monoblock sectioning technique (MST)-is difficult to apply to hard and brittle CAD/CAM materials such as zirconia and ceramics, thereby limiting test reproducibility. This study compared a newly developed defined-area bonding (DAB) method with MST to determine whether DAB could serve as a reliable specimen preparation technique for μTBS testing. CAD/CAM resin blocks and resin core materials were bonded using either ESTECEM II or Panavia V5. MST specimens were obtained by bonding the blocks first and subsequently sectioning them into individual beams. In contrast, DAB specimens were produced by pre-shaping the sticks and bonding them within a defined 1 mm2 area. μTBS, failure modes, and fracture/interface morphology (SEM) were evaluated. MST produced significantly higher μTBS values than DAB (p < 0.001), with central MST beams showing the highest bond strengths. DAB values were statistically equivalent to MST peripheral values for both cements. More than 80% of failures were cohesive within resin cement across all groups. SEM revealed uniform cement layer thickness (50-60 μm) and similar peripheral-like fracture patterns in DAB specimens. Although MST yielded higher μTBS overall, the DAB method produced bond strengths equivalent to the MST peripheral region and demonstrated consistent fracture characteristics. Because DAB requires minimal cutting, it offers a promising, reproducible approach for μTBS testing of high-hardness materials that are otherwise difficult to section.

With the growing clinical use of ion-releasing resin composites, their repairability has become an important consideration in minimally invasive restorative dentistry. Therefore, this study investigated the repair bond strength of a universal composite restorative to commercially available and experimental ion-releasing resin composite materials. Specimens (n = 8 per group) were produced from three commercially available ion-releasing composite materials (ACTIVA BioACTIVE-RESTORATIVE, Cention Forte, Beautifil II), one experimental ion-releasing resin composite containing 20 wt% bioactive glass fillers, and two conventional resin composites (3M Filtek Supreme XTE, Ceram.x Spectra ST), and aged by thermal cycling in artificial saliva (5000 cycles, 5-55 °C). Substrate surfaces were sandblasted (Al2O3, 50 µm), silanized (Monobond Plus), and repaired using adhesive (OptiBond FL) and universal resin composite (Ceram.x Spectra ST). After further thermal cycling, micro-tensile repair bond strength was assessed and analyzed using one-way ANOVA followed by Tukey's post hoc test. Failure modes were determined by stereomicroscopy (25× magnification) and statistically compared among the groups. Highest mean repair bond strength values were obtained for ACTIVA BioACTIVE-RESTORATIVE, Beautifil II, and 3M Filtek Supreme XTE (53.8, 46.2, and 43.0 MPa, respectively), which did not differ significantly among each other. ACTIVA BioACTIVE-RESTORATIVE attained significantly higher bond strength than the experimental composite, Ceram.x Spectra ST, and Cention Forte, and showed the highest incidence of cohesive failures (40%). No significant bond strength differences were detected among Beautifil II, 3M Filtek Supreme XTE, experimental composite, Ceram.x Spectra ST, and Cention Forte (36.2-46.2 MPa). In conclusion, ion-releasing resin composites can be repaired with conventional universal composite and show repair bond strength values at least as high as those of conventional composite materials.

Reliable bonding to dentin in high C-factor cavities remains a clinical challenge due to polymerization stress. Bulk-fill composites, including self- and dual-cured systems, aim to simplify placement and improve adaptation in deep cavities. However, limited data exist on how different dentin surface treatments affect their bond strength. Sixty extracted human molars with standardized Class I cavities were randomly assigned to six groups based on restorative system (self-curing bulk-fill, and a dual-cured bioactive composite system) and dentin treatment (self-etch, short 3-second etch, conventional etch-and-rinse). µTBS was evaluated after one month of water storage. Two-way ANOVA was used to assess the effects of material and dentin treatment, and failure modes were analyzed descriptively using Chi-square test. Dentin treatment significantly affected µTBS (p < 0.001), whereas the restorative system did not (p = 0.56). The highest µTBS was observed in the etch-and-rinse groups for both the self-cure (26.4 MPa) and the dual-cure systems (26.0 MPa), while the lowest values occurred in self-etch groups (self-cure: 18.0 MPa; dual-cure: 19.5 MPa). Failure mode analysis showed predominantly adhesive failures in self-etch groups and mixed failures in etch-and-rinse groups. Within the limitations of this study, etch-and-rinse dentin treatment appears to provide higher µTBS than self-etch. While short dentin etching could potentially offer a practical compromise, particularly for the self-curing bulk-fill composite. A short 3-second etch may improve bond strength over self-etch protocols, especially for the self-cure restorative system (Stela, SDI), suggesting a simple strategy to optimize adhesion while minimizing potential over-etching.

The current study aims to assess the dentin bonding performance of primary molars with dentinogenesis imperfecta type II (DGI-II). Moreover, we assess the efficacy of calcium phosphate polymer induced liquid precursor (Ca/P-PILP), a biomimetic remineralization material, in improving the resin bonding performance of DGI-II dentin. Dentin specimens from normal and DGI-II primary molars were treated with either Ca/P-PILP or double-distilled water. Morphology of these dentin specimens were observed using scanning electron microscopy (SEM), and the calcium and phosphorus contents were determined by energy-dispersive X-ray spectroscopy (EDS). Micro-tensile bond strength (µTBS) analysis was conducted to evaluate the resin bonding strength of dentin. SEM results showed that compared with normal dentin, DGI-II dentin exhibited significantly fewer dentinal tubules with nearly no intact tubular structures. Meanwhile, the dentin collagen fibers exhibited disorganized arrangement and compromised structural integrity. Compared with normal dentin, DGI-II dentin displayed inferior bonding performance with resin as shown by µTBS analysis, and EDS analyses showed that DGI-II dentin contained lower calcium and phosphorus contents. After treatment with Ca/P-PILP, the calcium and phosphorus contents of DGI-II dentin were significantly increased as shown by EDS analyses, and µTBS analysis showed that the bonding performance of DGI-II dentin was improved, while no notable effect was observed in normal dentin. Primary molars with DGI-II display structural defects and reduced calcium and phosphorus contents in dentin. The reduced mineral contents are partially responsible for the compromised bonding performance of DGI-II dentin, for Ca/P-PILP which effectively enhances the mineral contents of DGI-II dentin improves the resin bonding performance of DGI-II dentin.

Modification of a universal adhesive with CHX- or DOX-loaded TiO2 nanotubes as an anti-MMP strategy.

Dendrimer-based extrafibrillar demineralization for optimizing resin-dentin bond stability.

This study evaluates how different wavelength ranges emitted by a poly-wave LED curing light violet (405 nm) and blue (445 and 465 nm) affect the microtensile bond strength (μTBS), nanoleakage (NL), and in situ degree of conversion (DC) of universal adhesives applied to dentin. Eighty caries-free human molars were randomly assigned to four groups according to two variables: (1) Adhesive system (Ambar Universal APS [AMU], Scotchbond Universal [SBU] and (2) application mode (etch-and-rinse [ER] or self-etch [SE]). To control tooth dependency, each tooth quadrant of every tooth was allocated to a different wavelength range (405, 445 and 465 nm) and identified accordingly during light-curing with the Valo unit (1400 mW/cm2). Afterwards, resin composite fillings were placed, and each quadrant was sectioned to obtain resin-dentin bonded beams (0.8 mm2). These beams were tested for μTBS, NL, and DC. Data for μTBS (MPa), NL (%), and DC (%) were analyzed using three-way ANOVA and Tukey's test (α=5%). For AMU and SBU, no significant differences were observed among the 445-nm and 465-nm wavelength ranges (p > 0.05) for all outcomes. However, light curing SBU with 405-nm LED resulted in significantly lower μTBS and DC values and higher NL values compared with 445 and 465 nm LEDs (p < 0.01). AMU exhibited higher μTBS and DC values than SBU (p = 0.001). No significant differences were found between SE and ER application strategies (p > 0.05). Bonding to dentin may be locally compromised when universal adhesives relying on the conventional camphorquinone/amine photoinitiator system are light-cured with poly-wave LEDs that exhibit non-uniform spectral distribution.