Search Results (154)

Objectives: Limited information is available on how connector size and luting protocols influence the fracture resistance of 3D-printed resin-based fixed dental prostheses (FDPs). This in vitro study evaluated the effect of connector size and luting agent type on fracture load. Methods: Eighty 3-unit posterior FDPs were 3D-printed (GC Temp PRINT, GC Corp.) and assigned to eight groups (n = 10) by connector size (GroupA 5 × 5 mm or Group B 3 × 3 mm) and luting protocol (1: no cement; 2: TempBond temporary cement; 3: Ketac Cem glass ionomer; 4: G-Cem One self-adhesive resin cement). Specimens were seated on standardized metal abutments and loaded to failure (Instron 5567, 1 mm/min). Data analyzed by Shapiro–Wilk normality test, Mann–Whitney U (connector size), ANOVA/Kruskal–Wallis (luting within size; α = 0.05). Results: Connector size significantly affected fracture resistance (Mann–Whitney U, p < 0.001): 5 × 5 mm groups showed ~3× higher loads (1468–1638 N) than 3 × 3 mm groups (266–384 N). In 5 × 5 mm groups, luting protocol had no significant effect (ANOVA, p > 0.05). In 3 × 3 mm groups, resin cement (343 N) and temporary cement (384 N) showed higher loads than no-cement controls (266 N; Kruskal–Wallis p = 0.022, exploratory U p < 0.05); glass ionomer showed no significant difference. Conclusions: Within the limitations of this in vitro study, larger connectors substantially increased 3D-printed FDP fracture resistance. Resin-based luting agents increased loads in smaller-connector FDPs. Full article

Deep margin elevation (DME) is a conservative technique used to relocate subgingival proximal margins to a more favorable supragingival position, facilitating adhesive procedures and impression taking. This in vitro study evaluated the influence of two DME materials—a universal flowable resin composite and a self-adhesive flowable resin composite—on the cervical interfacial sealing ability of lithium disilicate glass–ceramic CAD/CAM inlay restorations. Twenty extracted maxillary premolars were randomly allocated into two groups (n = 10). Group A received DME using a universal flowable resin composite (3M™ Filtek™ Z350 XT) preceded by a conventional adhesive system, while Group B received DME using a self-adhesive flowable resin composite (Vertise™ Flow). All teeth were restored with lithium disilicate CAD/CAM inlays (CEREC Tessera) cemented with a self-adhesive resin cement (Breeze^®). Specimens underwent thermocycling (10,000 cycles; 5–55 °C). Marginal gaps were assessed at the DME interface using high-resolution micro-computed tomography (micro-CT) in both coronal and sagittal cross-sections, before and after thermocycling. Statistically significant differences were found between groups in both sections before and after thermocycling (p < 0.05). The self-adhesive composite (Group B) demonstrated significantly lower gap values compared to the universal flowable composite (Group A) in both coronal and sagittal assessments. Thermocycling increased the gap in both groups; however, Group B maintained considerably lower leakage. The self-adhesive resin composite showed superior sealing ability at the DME interface compared to the universal flowable composite when used under lithium disilicate glass–ceramic inlay restorations. Further clinical studies are recommended to validate these findings. Full article

To improve the dry cutting performance of YG8 cemented carbide tools, CaF₂/[BMIM]PF₆@PPSU solid–liquid dual-core microcapsules were incorporated into microtextures on the rake face, thereby constructing a microcapsule–microtexture composite self-lubricating tool system. Cutting experiments were conducted to systematically investigate the effects of microcapsule content and microtexture edge spacing on the cutting performance of the tools. The results indicate that optimal cutting performance is achieved at a microcapsule content of 20 wt.% and an edge spacing of 100 μm. Under these conditions, the tool embedded with dual-core microcapsules exhibited a main cutting force as low as 88.6 N, a cutting temperature of 237.8 °C, a machined surface roughness of 1.08 μm, and an extended cutting distance of 9497 m. Compared with the unlubricated tool, the main cutting force, axial force, and radial force decreased by approximately 40%, 45.6%, and 47.4%, respectively; the cutting temperature decreased by 43.9%, and the surface roughness was reduced by 24.5%. Micromorphological analysis reveals that, under optimal conditions, the TC2 tool effectively mitigates adhesive and delamination wear on both the rake and flank faces. Energy-dispersive spectroscopy (EDS) analysis demonstrates that the rupture of microcapsules releases two core materials, forming a stable solid–liquid biphasic lubricating film that effectively suppresses adhesive and abrasive wear. Full article

This article evaluates the mechanical performance of truly universal resin cements, which promise broad substrate compatibility, simplified self-adhesive dual-cure mechanisms, and functional monomers. It addresses the inconsistent classification of market materials labelled as ‘universal’ and the lack of clear guidelines. Flexural strength (FS), diametral tensile strength (DTS), and Vickers hardness (HV) of ten resin cements were evaluated: five classified as truly universal (RelyX Universal, Calibra Universal+, Nexus Universal, Panavia SA, SoloCem) and five conventional (Panavia V5, RelyX U200, Cem SE DC, G-Cem One, Maxcem Elite). Significant variations occurred across the tested materials. RelyX Universal exhibited the highest HV (68), while Panavia V5 the lowest (20). FS ranged from 73.0 MPa (Panavia SA) to 114.4 MPa (G-Cem One). Elastic modulus values were lowest for RelyX Universal (3638 MPa) and Panavia SA Cement Universal (3812 MPa), and highest for Cem SE DC (8092 MPa). DTS values were comparable across the groups (35.4–50.2 MPa). No clear differences were observed between cements classified as truly universal and conventional materials in terms of FS, DTS, or HV. However, significant variations were found among individual materials (p < 0.05), indicating that mechanical performance is material-dependent rather than classification-based. Greater transparency in product characterisation is essential to enable accurate material classification. Full article

The effects of different surface pretreatments on the microtensile bond strength (µTBS) between a bulk-fill resin-based composite cavity base material (Bulk Base HARD II) and 4-META/MMA-TBB resin (Super-Bond EX), which is often used as a luting agent for indirect dental restorations, were investigated. Six experimental treatments were established: 10% citric acid/3% ferric chloride conditioner (10-3), self-etching primer (Teeth Primer; TP), silane coupling agent (M&C Primer; MC), 10-3+MC, TP+MC, and a control group with no treatment. The µTBS was measured after 1 week (immediate group) and 6 months (aged group) of water storage. There were no significant differences in µTBS among the immediate subgroups. However, the aged 10-3+MC group exhibited the highest bond strength, significantly outperforming the control group. On the other hand, the µTBS of the aged TP group was significantly lower than those of both aged 10-3 and 10-3+MC. MC alone did not enhance bond strength, and its application after TP led to a nonuniform surface morphology, raising concerns about adhesive stability. Failure mode analysis indicated that cohesive failure within the luting cement was predominant, with mixed failures being more frequent in the aged TP group. Overall, MC may not be necessary, and 10-3 conditioning does not adversely affect bond strength. Based on the results of this in vitro study, the most effective clinical practice entails pretreatment of the prepared cavity employing a citric acid/ferric chloride conditioner. Full article

The aim of this study was to evaluate the biological effects of bioactive glass-containing self-adhesive resin cements (SARCs) on human dental pulp stem cells (DPSCs), focusing on cytocompatibility, odontogenic differentiation, and mineralization. Experimental SARCs containing 0–5 wt% BAG (BG0–BG5) were compared with two commercially available SARCs, RelyX U200 and TheraCem. Eluates were prepared and applied to DPSCs for the methylthiazol tetrazolium (MTT) assay, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) staining, and Alizarin Red S (ARS) staining. The result showed there were no significant differences in cell viability across all groups (p > 0.05), indicating that the addition of BAG did not affect cell viability, while the early odontogenic differentiation markers, such as RUNX2, ALP, and COL1A1, showed no clear trend among the groups. However, late-stage markers (DMP-1 and DSPP) were significantly higher in the BG2–BG5 groups relative to the OM group (p < 0.05). IF staining revealed intense signals in the BG2–BG5 groups (p < 0.05) and also ARS staining showed a time-dependent increase in mineral deposition. Within the limitations of this study, BAG-containing SARCs do not negatively impact cytocompatibility and promote late-stage odontogenic differentiation and mineral deposition. Full article

The reliability of adhesive bonding to CAD/CAM resin composites is influenced not only by material composition and surface treatment but also by the testing methodology used to assess bond strength. However, the impact of different shear bond strength (SBS) test configurations remains insufficiently clarified. This study evaluated the influence of different surface pretreatment protocols and SBS test methods on the bonding performance of a self-adhesive resin cement to two CAD/CAM materials: a conventional particulate-filled composite (Cerasmart 270) and an experimental short glass fiber-reinforced composite (SFRC CAD). Specimens (14 × 12 × 3 mm; n = 80 per material) were ground with 320-grit silicon carbide paper and divided according to surface pretreatment: airborne-particle abrasion (APA) or APA followed by hydrofluoric acid application for 60 s (APA + HF). Each group was further subdivided based on the SBS test method using either resin cement cylinders fabricated with a custom transparent mold (diameter: 3.6 mm; height: 3 mm) or metallic cylinders cemented to the treated surface. Half of the specimens were tested after 48 h of water storage, while the remainder underwent hydrothermal aging by boiling in water for 16 h prior to testing. Material type, SBS test method, surface pretreatment, and aging significantly affected bond strength (p < 0.05). The metallic cylinder method produced higher SBS values than the transparent mold technique, particularly for SFRC CAD. APA + HF tended to reduce SBS in Cerasmart 270, particularly after aging, whereas SFRC CAD showed comparable or higher bond strength values with APA alone. Aging decreased SBS in most groups. Overall, bond strength was influenced by both material type and test methodology. Within the limitations of this study, airborne-particle abrasion alone may be sufficient for SFRC CAD materials, while additional HF treatment may not provide further benefit. These findings highlight the importance of considering both material characteristics and test configuration when interpreting laboratory bond strength data. Full article

Non-carious cervical lesions (NCCLs) present restorative challenges due to substrate sclerosis and marginal stress concentration, making the adhesive strategy a key determinant of long-term performance. This systematic review and frequentist random-effects network meta-analysis, conducted in accordance with PRISMA 2020 and the PRISMA-NMA extension and prospectively registered in PROSPERO, compared restorative strategies defined by etching approach, adhesive category, and restorative material, with marginal adaptation and retention loss as the primary outcomes. PubMed, Web of Science, Cochrane Library, Embase, and Scopus were searched without restrictions (25 January 2026), supplemented by alternative retrieval methods. Randomized clinical trials in permanent teeth evaluating at least two etching-based strategies (etch-and-rinse, self-etch, selective-etch, and/or resin-modified glass ionomer cement (RMGI)) were included. Risk of bias was assessed using RoB 2 and certainty of evidence with CINeMA. Seventy-four trials were eligible. Connected networks were established for marginal adaptation (57 studies; 28 interventions; 6798 patients; 1772 events) and retention loss (61 studies; 33 interventions; 7338 patients; 584 events). Selective-etch with a universal adhesive and nanocomposite reduced marginal adaptation failure compared with RMGI, whereas certain self-etch and non-universal combinations increased risk. For retention loss, selective-etch and etch-and-rinse protocols combined with universal adhesives and nanocomposites showed lower failure rates, while some self-etch or non-universal adhesive strategies performed less favorably. Overall confidence was predominantly high, with downgrading mainly due to imprecision and heterogeneity. Strategies incorporating selective enamel etching or etch-and-rinse approaches combined with universal adhesives and nanocomposites demonstrated the most consistent clinical advantages. Full article

This study compared three internal surface treatments of zirconia copings—silane alone (control), airborne-particle abrasion followed by silane, and high-temperature hydrofluoric acid etching followed by silane—regarding initial pull-out retention strength, retention after thermocycling, failure mode assessed by scanning electron microscopy (SEM), and surface wettability. Sixty-three monolithic zirconia copings were allocated to three groups (n = 21) according to surface treatment and cemented to titanium bases with a self-adhesive resin cement. Initial pull-out tests were performed. A subset (n = 10 per group) underwent thermocycling followed by repeat testing. Failure modes were analysed by SEM, and wettability was measured using the sessile drop method. Surface roughness and crystalline phase were additionally characterized by white-light interferometry and X-ray diffraction (XRD), respectively. High-temperature acid etching produced significantly higher initial pull-out forces than airborne-particle abrasion and silane alone, with mean values 125% higher than control and 42.6% higher than airborne-particle abrasion. After thermocycling, acid-etched specimens maintained the highest retention, whereas airborne-particle abrasion showed critical loss. SEM revealed predominantly cement remnants on zirconia in the acid-etched group, indicating a stronger zirconia–cement interface. Acid etching also yielded significantly lower contact angles, reflecting improved wettability. High-temperature hydrofluoric acid etching followed by silanization provided superior and more stable retention, more favourable failure modes, and improved wettability. Full article

The ongoing concern about sustainable infrastructure has driven the development of cement-based adhesives (CBAs) for fibre-reinforced polymer (FRP)-based concrete retrofitting. Nevertheless, traditional CBAs usually have low bond strength, low crack resistance, and low long-term durability that undermine the performance of FRP–concrete systems. To address these limitations, this focused review examines the potential of nanomaterial-modified CBAs to enhance interfacial bond behaviour and overall structural performance. A systematic assessment of recent experimental studies was used to analyze CBAs modified with nanosilica, carbon nanotubes, graphene oxide, and other nanomaterials. The roles of these nanomaterials in improving adhesion mechanisms, stress transfer efficiency, crack control, and resistance to environmental stressors are critically discussed. We also contrast the performance of neat and nano-modified CBAs in FRP-based retrofitting systems, with particular emphasis on bond behaviour, mechanical response, and durability-related performance. Particular emphasis is put on innovative high-strength self-compacting cementitious adhesives (IHSSC-CAs), which are identified as an emerging class of sustainable bonding materials combining high mechanical performance with improved environmental compatibility in relation to traditional bonding systems. The paper concludes with the identification of key research gaps, a discussion of practical implementation challenges, and an outline of future research directions for the development of next-generation sustainable and resilient concrete retrofitting technologies. Full article

Background/Objectives: The classification of adhesive systems has historically relied on the type of etching agent and the sequence of application steps, distinguishing etch-and-rinse and self-etch categories. However, these models do not encompass the versatility introduced by universal adhesives or other emerging polymeric materials. This review aimed to integrate etching technique as a defining parameter within adhesive classification, linking material composition, bonding strategy, and clinical execution into a coherent functional framework. Methods: A structured narrative review of experimental, translational, and clinical studies published between 2010 and 2025 was conducted using PubMed and Scopus. Literature addressing adhesive categories, etching strategies, etching techniques, and smear layer characteristics was critically synthesized to identify functional relationships relevant to bonding performance and clinical decision-making. Results: The proposed taxonomy classifies materials as conventional, universal, touch-cure primers, self-adhesive/universal, and glass ionomer cements. Bonding strategies are organized as etch-and-rinse, self-etch, pre-etched, and unassisted, while etching techniques are defined as selective or nonselective families encompassing five clinically defined techniques. Incorporating etching technique clarifies the role of smear layer density, the acidity of adhesive materials, and functional monomer reactivity in demineralization and bonding. This structure enhances the understanding and teaching of adhesive concepts and supports evidence-based clinical selection of materials and techniques. Conclusions: Integrating etching technique into adhesive classification provides a functional and dynamic framework that unifies material, strategy, and technique. This taxonomy facilitates clinical decision-making and can evolve with future adhesive formulations. Further independent, long-term studies are warranted to validate the proposed combinations of materials and etching procedures. Full article

The objective of this in vitro study was to investigate the effects of dentin pretreatment protocols and thermocycling on the shear bond strength (SBS) of a self-adhesive resin cement (Maxcem elite chroma) on dentin. A total of 168 extracted human third molars were randomly divided into four main groups according to dentin pretreatment: no treatment, 10% polyacrylic acid, Optibond universal, and Scotchbond universal plus. Half of these were subjected to thermocycling (5000 cycles; 5–55 °C). Composite resin rods were bonded using the self-adhesive resin cement, and SBS was measured with a universal testing machine. Two-way ANOVA showed that dentin pretreatment and thermocycling significantly affected SBS, with significant interaction between factors (p < 0.001). The highest SBS was observed in the Optibond universal group (18.71 ± 0.43 MPa), while the lowest SBS occurred in the 10% polyacrylic acid-treated group after thermocycling (2.69 ± 0.39 MPa). Thermocycling significantly reduced SBS in all groups. These results indicate that pretreatment with a compatible universal adhesive improves bond durability, whereas 10% polyacrylic acid pretreatment adversely affects bonding performance. Full article

Background/Objectives: Marginal fit is a key determinant of the clinical performance of CAD/CAM (Computer-Aided DesignComputer-Aided Manufacturing) inlay restorations. This in vitro study compared the vertical marginal gap (VMG) of three chairside CAD/CAM inlay materials—VITA Enamic, CEREC Tessera, and Celtra Duo—using scanning electron microscopy (SEM) under a standardized digital workflow. Methods: Standardized Class I inlay preparations were performed in 15 extracted human molars (n = 5/material). Restorations were fabricated using a chairside workflow (Primescan intraoral scanning, CEREC 5.3 design, Primemill milling) followed by material-specific surface treatment and cementation with a self-adhesive resin cement. VMG was measured on SEM micrographs (500× for quantitative measurements; 200× for orientation) at three sites (mesial, central, distal), with three points per site (nine points/tooth; 135 point measurements). Triplicate points were averaged to site-level means and analyzed using a linear mixed-effects model (fixed effects: material, site, material × site; random intercept: tooth), Type II ANOVA, and Tukey-adjusted pairwise comparisons. Results: Mean VMG values were lowest for Celtra Duo (8.09 ± 1.98 µm), followed by VITA Enamic (27.90 ± 29.76 µm) and CEREC Tessera (32.72 ± 21.80 µm). The model indicated an overall effect of material (F(2,36) = 3.51, p = 0.040), whereas site and material × site effects were not significant. Tukey-adjusted pairwise comparisons did not reach statistical significance. Conclusions: Within the standardized chairside workflow evaluated, an overall material effect on VMG was detected, but pairwise separation was inconclusive in this sample with overlapping distributions. Celtra Duo showed smaller VMG values with narrower dispersion in overall per-tooth means, while VITA Enamic and CEREC Tessera showed wider and overlapping distributions; all group means were below commonly cited clinical acceptability ranges for marginal gap. Full article

This study evaluated the bond strength of self-adhesive resin cement (SARC) containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and calcium silicate, with and without zirconia primer, before and after thermocycling. Sintered zirconia specimens (n = 180) were sequentially polished, sandblasted, and bonded with TheraCem (TC), Clearfil SA Luting (SA), or Rely X U200 (RU), with and without Z-Prime Plus primer. Specimens were stored in water at 37 °C or subjected to 10,000 thermocycles (5–55 °C). Shear bond strength (SBS), failure modes, fracture surfaces, flexural strength, and Vickers hardness were assessed. Bonding performance was governed by material-specific interactions rather than a complex three-factor interplay between resin cement type, primer application, and thermocycling. SBS followed the order TC > SA > RU and was significantly higher with primer application. Thermocycling significantly reduced SBS in all groups. Premature failure occurred in the RU and SA groups. Mixed failure was predominant across all conditions. The flexural strength and Vickers hardness were highest in the RU group, followed by the TC and SA groups, with RU maintaining significantly higher hardness even after thermocycling. Overall, SARCs containing MDP and calcium silicate demonstrated favorable bonding performance, which was further enhanced by zirconia primer application. Full article

This in vitro study evaluated the shear bond strength (SBS) of four CAD/CAM (Computer aided design/Computer aided manufacturing) polymer-based indirect composites bonded to dentin and microhybrid composite substrates using two resin cements. Gradia Plus (GP), Ceramage (Ce), Tescera ATL (TA), and Lava Ultimate (LA) were fabricated into cylindrical specimens (3 × 3 mm). Dentin substrates were obtained from extracted molars, while composite substrates were prepared from Filtek Z250 (4 mm × 2 mm). Bonding was performed using either a self-adhesive resin cement (RelyX U200; RU200) or a dual-cure adhesive resin cement (RelyX Ultimate; RU), resulting in 16 experimental groups (n = 12 per group). SBS was measured using a universal testing machine (1 mm/min), and failure modes were assessed under stereomicroscopy. Bond strength was significantly higher on composite substrates than on dentin (p < 0.001), primarily due to favorable polymer–polymer compatibility and matrix interdiffusion, which improved stress accommodation at the adhesive interface. TA and Ce showed superior adhesion when combined with RU, while LA exhibited the lowest values, particularly on dentin bonded with RU200. Overall, the dual-cure adhesive system provided stronger bonding than the self-adhesive system (p < 0.05). These findings highlight the influence of substrate type, composite architecture, and cement chemistry on interfacial performance in indirect polymer-based restorations. Full article