The use of protein cross-linking agents during bonding procedures has been recently proposed to improve bond durability. This study aimed to use zymography and in situ zymography techniques to evaluate the ability of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linker to inhibit matrix metalloproteinase (MMP) activity. The hypotheses tested were that: (1) bonding procedures increase dentin gelatinolytic activity and (2) EDC pre-treatment prevents this enzymatic activity. The zymographic assay was performed on protein extracts obtained from dentin powder treated with Optibond FL or Scotchbond 1XT with or without 0.3M EDC pre-treatment. For in situ zymography, adhesive/dentin interfaces were created with the same adhesives applied to acid-etched dentin slabs pre-treated or not with EDC conditioner. Zymograms revealed increased expression of dentin endogenous MMP-2 and -9 after adhesive application, while the use of EDC as a primer inactivated dentin gelatinases. Results of in situ zymograpy showed that hybrid layers of tested adhesives exhibited intense collagenolytic activity, while almost no fluorescence signal was detected when specimens were pre-treated with EDC. The correlative analysis used in this study demonstrated that EDC could contribute to inactivate endogenous dentin MMPs within the hybrid layer created by etch-and-rinse adhesives.

This study was performed to evaluate the effects of different in vitro ageing techniques on the dentine-bonded interface produced by a two-step etch-and-rinse adhesive. Composite build-ups were bonded to sectioned human molars using XP BOND and cut into non-trimmed dentine-composite beams for microtensile testing. Beams were assigned to one of the following storage conditions: (i) artificial saliva, 24 h (control); (ii) 10% sodium hypochlorite (NaOCl), 1 h; (iii) 10% NaOCl, 3 h; (iv) 60,000 thermal cycles, 2 months; (v) artificial saliva, 2 months; (vi) 60,000 thermal cycles, 6 months; and (vii) artificial saliva, 6 months. Beams were then pulled until failure and bond strength was calculated. Additional specimens were examined to investigate interfacial nanoleakage expression. NaOCl solution significantly reduced bonding compared with the control (group 2 = group 3 < group 1); and thermocycling reduced the bond strength in comparison to specimens stored for the same time-period in artificial saliva (group 4 < group 5; group 6 < group 7). Artificial ageing affected bond strength only after 6 months of storage (group 7 < group 5 = group 1). Increased nanoleakage was found under all ageing conditions in comparison with controls. NaOCl solution is a rapid and reliable in vitro ageing method for examining the durability of the adhesive interface produced by two-step etch-and-rinse adhesive systems.

Calcium silicate cements (CSCs) are the choice materials for vital pulp therapy because of their bioactive properties, promotion of pulp repair, and dentin bridge formation. Despite the significant progress made in understanding CSCs’ mechanisms of action, the key events that characterize the early interplay between CSC-dentin-pulp are still poorly understood. To address this gap, a microfluidic device, the “tooth-on-a-chip,” which was developed to emulate the biomaterial-dentin-pulp interface, was used to test 1) the effect of CSCs (ProRoot, Biodentine, and TheraCal) on the viability and proliferation of human dental pulp stem cells, 2) variations of pH, and 3) release within the pulp chamber of transforming growth factor–β (TGFβ) as a surrogate of the bioactive dentin matrix molecules. ProRoot significantly increased the extraction of TGFβ ( P < 0.05) within 24 to 72 h and, along with Biodentine, induced higher cell proliferation ( P > 0.05), while TheraCal decreased cell viability and provoked atypical changes in cell morphology. No correlation between TGFβ levels and pH was observed. Further, we established a biofilm of Streptococcus mutans on-chip to model the biomaterial-biofilm-dentin interface and conducted a live and dead assay to test the antimicrobial capability of ProRoot in real time. In conclusion, the device allows for direct characterization of the interaction of bioactive dental materials with the dentin-pulp complex on a model of restored tooth while enabling assessment of antibiofilm properties at the interface in real time that was previously unattainable.

This study is aimed at evaluating the effects of triclosan-encapsulated halloysite nanotubes (HNT/TCN) on the physicochemical and microbiological properties of an experimental dental composite. A resin composite doped with HNT/TCN (8% w/w), a control resin composite without nanotubes (HNT/TCN-0%) and a commercial nanofilled resin (CN) were assessed for degree of conversion (DC), flexural strength (FS), flexural modulus (FM), polymerization stress (PS), dynamic thermomechanical (DMA) and thermogravimetric analysis (TGA). The antibacterial properties (M) were also evaluated using a 5-day biofilm assay (CFU/mL). Data was submitted to one-way ANOVA and Tukey tests. There was no significant statistical difference in DC, FM and RU between the tested composites (p > 0.05). The FS and CN values attained with the HNT/TCN composite were higher (p < 0.05) than those obtained with the HNT/TCN-0%. The DMA analysis showed significant differences in the TAN δ (p = 0.006) and Tg (p = 0) between the groups. TGA curves showed significant differences between the groups in terms of degradation (p = 0.046) and weight loss (p = 0.317). The addition of HNT/TCN induced higher PS, although no significant antimicrobial effect was observed (p = 0.977) between the groups for CFUs and (p = 0.557) dry weight. The incorporation of HNT/TCN showed improvements in physicochemical and mechanical properties of resin composites. Such material may represent an alternative choice for therapeutic restorative treatments, although no significance was found in terms of antibacterial properties. However, it is possible that current antibacterial tests, as the one used in this laboratory study, may not be totally appropriate for the evaluation of resin composites, unless accompanied with aging protocols (e.g., thermocycling and load cycling) that allow the release of therapeutic agents incorporated in such materials.