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Objectives: Currently, a classification of resin cements that includes relatively recently formulated ("universal") cements is lacking. Furthermore, the terminology used to define different resin cements in the scientific reports is inconsistent. Accordingly, this work aims to: (i) propose a novel classification of resin composite cements; (ii) disambiguate the term "universal cements" and (iii) present an overview of the properties of these cements. Methods: An analysis of peer‐reviewed literature (PubMed search), as well as market research on definitive resin composite cements were performed. Results: A tendency toward simplified and versatile luting materials was observed both in the scientific literature and on the dental market with the advent of self‐adhesive/one‐step resin cements. However, additional priming procedures were necessary to improve their bonding performance in certain clinical situations. Hence, several cements that can be applied both in adhesive and self‐adhesive mode were introduced. These cements are associated with a universal adhesive resin, that can be used as a tooth and/or restorative material primer, without the need for other priming systems, regardless of the substrate. These systems should be considered truly universal. Therefore, we hereby suggested a new classification of resin‐based cements: (1) adhesive/multi‐step; (2) self‐adhesive/one‐step; (3) universal cements (one‐ or multi‐step). Despite promising in vitro results, clinical trials and long‐track laboratory studies are necessary to confirm the reliability of the universal cements. Conclusions: This review presented the current advances in the field of resin‐based cements, which are reflected in the proposed classification. The term "universal cement" was disambiguated, which will help standardize the terminology used in published research. Clinical Significance: The classification of resin‐based cements and a better understanding of the proper terminology will help standardize the terminology in published research, as well as improve the understanding of the clinical practitioners of the different indications and possible modalities of use of the available cements. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effect of CHX pre-treatment on long-term bond strength of fiber posts luted with self-adhesive resin cements. Materials and Methods: Seventy-two single-rooted teeth were selected for root canal treatment and post space preparation. The tested self-adhesive cement/post combinations were (N = 36): 1. RelyX Fiber-Posts luted with RelyX Unicem; 2. Rebilda Posts luted with Bifix SE Cement. For both self-adhesive cements, half of the specimens (experimental groups) were luted after the application of a solution of 2% CHX, while no CHX application was performed for the remaining specimens (control groups). Luted specimens were cut and used for push-out bond strength evaluation immediately, and after storage in artificial saliva for 6 months or 1 year. Additional specimens were processed for quantitative interfacial nanoleakage analysis. Results: ANOVA showed that the variable times of storage had a significant influence on the results (p < 0.05), while no influence of the luting procedure (cements with or without CHX) on the final outcome (p > 0.05) was found. Tukey’s pairwise post-hoc test showed that the radicular bond strength decreased with time of storage. In particular, a significant difference was found between T0 and T1y, but not between T0 and T6m. In contrast, in terms of pre-treatment, no significant reduction in push-out bond strength was observed, irrespective of the aging time. Conclusion: CHX pretreatment did not prevent bond strength degradation of fiber posts luted with self-adhesive cements. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of light curing on the microtensile bond strength (μTBS) and nanoleakage (NL) expression of a simplified universal adhesive used in combination with dual-cure resin cements. Observations were performed at 24 h and after 1-year aging. Materials and Methods: Twenty composite overlays (made by layering 2-mm-thick increments of Venus Diamond, shade A3) were luted to deep coronal dentin according to the following bonding procedures: 1) iBond Universal adhesive/RelyX Ultimate cement (UNI; Heraeus Kulzer/3M); 2) RelyX Unicem self-adhesive resin cement (RXU; 3M). Two subgroups were randomly formed according to the polymerization mode of the resin cements (n = 5): self-cure mode (SC; 1 h at 37°C) or dual-cure mode (DC, light output > 500 mW/cm², wavelength 440-480 nm; 20 s light curing followed by 15 min self-curing at 37°C). Each specimen was cut into microtensile sticks (1 mm2) which were either immediately stressed to failure under tension or aged in artificial saliva for 1 year before testing. The fracture pattern was evaluated under SEM. μTBS data were statistically analyzed with two-way ANOVA/Tukey's test (α = 0.05) including premature failures. Additional specimens were processed for quantitative interfacial NL expression using ammoniacal silver nitrate. Results: The factor SC statistically influenced the μTBS and nanoleakage of the tested groups, both at 24 h and 1 year of storage (p < 0.05). UNI/DC attained the highest immediate bond strengths (40.8 ± 10.4 MPa), while RXU/SC recorded the lowest μTBS among the groups at 24 h (8.4 ± 5.5 MPa). One-year aging negatively influenced the bond strengths of all tested groups, although the materials attained higher bond strengths when the DC mode was used. After 24 h, a higher amount of AgNO3 deposits was observed when the materials were used in SC modality, independent of the adhesive used. Nanoleakage increased after aging in all the tested groups. Conclusion: Light curing influences the bonding ability of simplified bonding systems compared to the self-cure modality. Storage time significantly affected the bond strengths and the interfacial nanoleakage expression of the tested materials. [ABSTRACT FROM AUTHOR]

Purpose: Cross-linkers, such as 1-ethyl-3(3-dimethyl-aminopropyl) carbodiimide (EDC), and carbo-diimide hydrochlorideethyl- 3-[3-dimethylaminopropyl] (DCC), might enhance the longevity of the hybrid layer and inhibit the endogenous dentinal enzymatic activity. The aim of this study was to investigate the influence of EDC and DCC on dentin bond strength and enzymatic activity using microtensile bond strength test (μTBS) and in-situ zymography. Materials and Methods: Non-carious teeth (N = 8 per group) were cut to expose middle/deep dentin, randomly assigned to 3 groups, etched for 15 s and treated according to the manufacturer's instructions: G1: DCC 0.5M ethanol solution for 1 min and bonded with Adper Scotchbond 1XT (SB1XT, 3M); G2: EDC 0.5M aqueous solution for 1 min and bonded with SB1XT; G3: bonded with SB1XT (control). Specimens were further subjected to μTBS and stressed until failure after 24 h (T0) or 12 months aging (T12) in artificial saliva at 37°C. Further, gelatine zymography was performed on dentin powder to examine the influence of cross-linkers on the activity of matrix metalloproteinases. The data were analyzed using two-way ANOVA with the significance set at α = 0.05. Results: Treatment as well as aging significantly influenced bond strengths (p < 0.05). The highest bond strength was shown in the EDC-pretreated group (p < 0.05). Lower bond strengths were recorded in all the groups after aging. However, the values were still the highest in the EDC-pretreated compared to other tested groups (p < 0.05). The enzymatic activity of both mmP-2 and -9 was inhibited in all the groups treated with one of the tested cross-linkers. Conclusion: The use of EDC aqueous solution seems to have a positive influence on the longevity of the hybrid layer and a pronounced enzymatic activity. Despite the anti-MMP activity, the DCC primer did not exhibit a positive influence on bond strength over time, possibly due to negative interactions with the adhesive resin. [ABSTRACT FROM AUTHOR]

An endodontically treated tooth with mesial-occlusal-distal (MOD) cavity is often restored with composite resin. Palatal and buccal cusp reduction (MODP, MODPB), and/or fiber-reinforced composite posts (P), are used in an attempt to improve the longevity of the restoration. The aim of this study was to determine the effects of these procedures on von Mises stress values and distribution in dental tissues and restorative materials using finite element analysis. Based on CT scans of an extracted second upper premolar, six 3D endodontically treated tooth models (MOD, MODP, MODPB, MOD+P, MODP+P, MODPB+P) were created. Each model was subjected to a summary force of 150 N on the occlusal surface simulating the normal biting pattern and maximal von Mises stresses were calculated. MODP seems to reduce von Mises stress values in dental tissues and P seems to transfer some of the stresses from dental tissues to the composite filling. [ABSTRACT FROM AUTHOR]

Purpose: Traditional dentin demineralization with phosphoric acid can contribute to the activation of dentinal proteolytic enzymes. Dentinal matrix metalloproteinases (MMPs), particularly MMP-2 and -9 have been shown to contribute to the degradation of the hybrid layer. To address this issue, a novel, self-limiting etchant has been developed. Using gelatin zymo - graphy, the aim of this study was to investigate the influence of an experimental etchant on the activity of the MMPs, compared to the traditional etching with phosphoric acid. Materials and Methods: Aliquots of dentin powder, obtained from eight human third molars, were treated as follows: G1: dentin powder left mineralized, as control; G2: dentin powder demineralized with Ivoclar Vivadent Experimental Etchant; G3: dentin powder demineralized with phosphoric acid. The protein content of the samples was extracted, concentrated, and quantified. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE, 10%) was performed under non-reducing conditions. Proteolytic activity was registered under long-wave UV light scanner and evaluated using the ImageJ software. Results: The qualitative and quantitative results showed low enzymatic activity in the mineralized dentin in the bands that correspond to molecular weight of pro- and active MMP-9. In dentin demineralized with phosphoric acid, the active form of MMP-9 was more pronounced, and also a band in the molecular weight of the active MMP-2 could be noted. The experimental etchant showed enzymatic activity in the band that corresponds to molecular weight of pro-MMP-9. The activity is slightly lower than the corresponding band in the group demineralized with phosphoric acid. Conclusion: This in vitro experiment showed a lower enzymatic activity in the experimental etchant group. Hence, the new etchant demonstrated promising results in terms of potential inhibitory effects on dentin gelatinases. However, further studies on the long-term influence of the novel etchant on the dentinal enzymatic activity and bond strength are required. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth (n = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups (p < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to evaluate the hardness and shrinkage stress (SS) of six bulk-fill resin composites. To evaluate microhardness (MH), ten 6 mm specimens were prepared using a metal mold for each selected bulk-fill resin composite and irradiated from the top side for 40 s using an LED light. After 24 h of storage, Vickers MH was evaluated on the upper, lower and lateral sides of the specimens. SS evaluation was then performed with a universal machine, which evaluated the contraction force generated by a bulk-fill composite specimen placed between two metal cylinders during and after light curing. The results were evaluated with a one-way ANOVA test with a post-hoc Bonferroni test and linear regression analysis (p < 0.05). All materials showed a significant MH decrease between the top and bottom surfaces. However, the bulk-fill materials tested performed differently when considering lateral depth progression. ANOVA tests for SS evaluation showed that both SDR and Venus Bulk Fill had significantly lower stress during irradiation than other tested materials. Further, MH decrease became significantly lower from the top surface at different depths in each tested group. Among the different resins, Venus Bulk Fill and SDR showed not only inferior hardness, but also a significant reduction in SS. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the effect of 0.1% chitosan (Ch) solution as an additional primer on the mechanical durability and enzymatic activity on dentine using an etch-and-rinse (E&R) adhesive and a universal self-etch (SE) adhesive. Microtensile bond strength and interfacial nanoleakage expression of the bonded interfaces for all adhesives (with or without pretreatment with 0.1% Ch solution for 1 min and air-dried for 5 s) were analyzed immediately and after 10,000 thermocycles. Zymograms of protein extracts from human dentine powder incubated with Optibond FL and Scotchbond Universal on untreated or Ch-treated dentine were obtained to examine dentine matrix metalloproteinase (MMP) activities. The use of 0.1% Ch solution as an additional primer in conjunction with the E&R or SE adhesive did not appear to have influenced the immediate bond strength (T0) or bond strength after thermocycling (T1). Zymography showed a reduction in MMP activities only for mineralized and demineralized dentine powder after the application of Ch. Application of 0.1% Ch solution does not increase the longevity of resin–dentine bonds. Nonetheless, the procedure appears to be proficient in reducing dentine MMP activities within groups without adhesive treatments. Further studies are required to comprehend the cross-linking of Ch with dentine collagen. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to investigate the influence of three post-and-core systems and two crown materials on stresses in restored premolars using Finite Element Analysis (FEA)., Materials and Methods: A maxillary second premolar 3D model was created in SolidWorks 2014 (Dassault Systémés). Severe loss of tooth structure was simulated with six restorative options: 1) glass-fiber-reinforced composite post and composite core (GFRC)+CAD/CAM leucite-reinforced glass-ceramic crown (LRC); 2) carbon-fiberreinforced composite post and composite core (CFRC)+LRC; 3) metal cast post-and-core (MPC)+LRC 4) GFRC+CAD/CAM composite resin crown (CC); 5) CFRC+CC; 6) MPC+CC. Three-point occlusal loading (150N) was simulated and von Misses and maximum principal stresses calculated., Results: Although maximum von Mises stresses in the crown and dentin were similar across groups (137.9-139.2MPa crown; 17.2-19.6 dentin), there were important differences in stress distribution in dentin. Only in MPC+CC group the maximum stresses were on the bottom of the post preparation cavity. Stress values within the posts were: CFRC(4.8MPa)>GFRC(6.7MPa)>MPC(10.3MPa). CC-restored models presented higher von Mises stresses within the post-and-core compared to the LRC groups. Maximum principal stresses were lower compared to von Mises stresses, following the same trend, and were distributed similarly in all the groups., Conclusions: Both GFRC and CFRC showed favourable stresses distribution in the dentin and restorative materials, while MPC increased stresses in core, post and post cement. The more rigid crown material seems to transmit less stresses to the underlying core and crown cement compared to CC.