Dentin bonding systems: From dentin collagen structure to bond preservation and clinical applications

The aim of this study was to systematically review the literature for in vitro and ex vivo studies that evaluated the effect of matrix metalloproteinase (MMP) inhibitors during the adhesive procedure on the immediate and long-term resin-dentin bond strength. The search was conducted in 6 databases with no publication year or language limits, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From 1,336 potentially eligible studies, 48 were selected for full-text analysis, and 30 were included for review, with 17 considered in the meta-analysis. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Pooled effect estimates were expressed as the weighted mean difference between groups. The most used MMP inhibitor was chlorhexidine (CHX). Immediate bond strength results showed no difference between 2% CHX and control; however, a difference was found between 0.2% CHX and control at baseline. After aging, CHX presented higher bond strength values compared to control groups (p < .05). However, this was not observed for longer periods of aging. High heterogeneity was found in some comparisons, especially for the water storage aging subgroup. Subgroup analyses showed that self-etching and etch-and-rinse adhesives are benefited by the CHX use. From the studies included, only 1 presented low risk of bias, while the others showed medium or high risk of bias. The use of MMP inhibitors did not affect the immediate bond strength overall, while it influenced the aged bond strength. Aging procedures influenced bond strength values of the dentin adhesion stability.

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MMP Inhibitors on Dentin Stability A Systematic Review and Meta-analysis

Traditional surgical intervention and antibiotic treatment are poor and even invalid for chronic diseases including periodontitis induced by diverse oral pathogens, which often causes progressive destruction of tissues, even tooth loss, and systemic diseases. Herein, an ointment comprising atomic-layer Fe2O3-modified two-dimensional porphyrinic metal-organic framework (2D MOF) nanosheets is designed by incorporating a polyethylene glycol matrix. After the atomic layer deposition surface engineering, the enhanced photocatalytic activity of the 2D MOF heterointerface results from lower adsorption energy and more charge transfer amounts due to the synergistic effect of metal-linker bridging units, abundant active sites, and an excellent light-harvesting network. This biocompatible and biodegradable 2D MOF-based heterostructure exhibits broad-spectrum antimicrobial activity (99.87 ± 0.09%, 99.57 ± 0.21%, and 99.03 ± 0.24%) against diverse oral pathogens (Porphyromonas gingivalis, Fusobacterium nucleatum, and Staphylococcus aureus) by the synergistic effect of reactive oxygen species and released ions. This photodynamic ion therapy exhibits a superior therapeutic effect to the reported clinical periodontitis treatment owing to rapid antibacterial activity, alleviative inflammation, and improved angiogenesis.

2D MOF Periodontitis Photodynamic Ion Therapy.

The critical barrier to progress in dentine bonding with the etch-and-rinse technique.

Since the last few decades, the development of smart hydrogels, which can respond to stimuli and adapt their responses based on external cues from their environments, has become a thriving research frontier in the biomedical engineering field. Nowadays, drug delivery systems have received great attention and smart hydrogels can be potentially used in these systems due to their high stability, physicochemical properties, and biocompatibility. Smart hydrogels can change their hydrophilicity, swelling ability, physical properties, and molecules permeability, influenced by external stimuli such as pH, temperature, electrical and magnetic fields, light, and the biomolecules’ concentration, thus resulting in the controlled release of the loaded drugs. Herein, this review encompasses the latest investigations in the field of stimuli-responsive drug-loaded hydrogels and our contribution to this matter.

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Smart Hydrogels for Advanced Drug Delivery Systems

Peri-implant infection is one of the biggest threats to the success of dental implant. Existing coatings on titanium surfaces exhibit rapid decrease in antibacterial efficacy, which is difficult to promisingly prevent peri-implant infection. Herein, we report an N-halamine polymeric coating on titanium surface that simultaneously has long-lasting renewable antibacterial efficacy with good stability and biocompatibility. Our coating is powerfully biocidal against both main pathogenic bacteria of peri-implant infection and complex bacteria from peri-implantitis patients. More importantly, its antibacterial efficacy can persist for a long term (e.g., 12~16 weeks) in vitro, in animal model, and even in human oral cavity, which generally covers the whole formation process of osseointegrated interface. Furthermore, after consumption, it can regain its antibacterial ability by facile rechlorination, highlighting a valuable concept of renewable antibacterial coating in dental implant. These findings indicate an appealing application prospect for prevention and treatment of peri-implant infection.

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Long-lasting renewable antibacterial porous polymeric coatings enable titanium biomaterials to prevent and treat peri-implant infection

PURPOSE To analyze the effects of different processes during bonding on endogenous cysteine cathepsin activity in dentin. MATERIALS AND METHODS Dentin powder, prepared from extracted human third molars, was divided into 10 groups. Two lots of dentin powder were used to detect the effects of the procedure of protein extraction on endogenous cathepsin activity. The others were used to study effects of different acid-etching or adhesive treatments on enzyme activity. Concentrations of 37% phosphoric acid or 10% phosphoric acid, two etch-and-rinse adhesive systems, and two self-etching adhesive systems were used as dentin powder treatments. The untreated mineralized dentin powder was set as the control. After treatment, the proteins of each group were extracted. The total cathepsin activity in the extracts of each group was monitored with a fluorescence reader. RESULTS In the control group, there were no significant differences in cathepsin activity between the protein extract before EDTA treatment and the protein extract after EDTA treatment (p > 0.05). The cathepsin activities of the three different extracts in the 37% phosphoric acid-treated group were different from each other (p 0.05). Treating the dentin powder with any of the two self-etching adhesives resulted in an increase in cathepsin activity (p < 0.05). CONCLUSIONS The activity of cysteine cathepsins can be detected in dentin powder. Treatment with EDTA during protein extraction exerted an influence on cathepsin activity. Acid etching or etch-and-rinse adhesive systems may reduce the activity of endogenous cathepsins in dentin. Self-etching adhesive systems may increase the enzyme activity.

Effects of acid etching and adhesive treatments on host-derived cysteine cathepsin activity in dentin.

Objective To evaluate the effect of concentration of chlorhexidine on bonding durability of dentine and resin. Methods Forty extracted third molars were randomly allocated into five groups, which include one control group and four test groups. Teeth dentin surfaces in each group were treated with one of the following solution, 1.5 μl water(control), 0. 02%, 0. 2%, 2% and 20% chlorhexidine. Single Bond 2 adhesive was applied to the dentin surface according to manufacturer's recommendations. Then 5 mm thickness of composite (Z250) was built up on the dentin of each molar. The teeth were sectioned into mierotensile samples and subdivided into two subgroups, 16 samples each. Samples in subgroup Ⅱ and Ⅰ were tested after being stored in distilled water for 24 h and 6 month respectively. Each fractured sample was examined with SEM. Results No significant differences of 24 h bonding strength were found among the five groups. There were significant difference in bonding strength between 0. 2%, 2% chlorhexidine groups [(24. 68±5. 26) and (23. 19±5. 26) MPa]and the control group[(19. 10±4. 67) MPa]after 6 month (P = 0. 007,0. 045), and significant differences were also found between 0. 2%, 2% and 0. 02% ehlorhexidine group[(19.01 ±6. 87) MPa, P =0. 006, 0. 041). Most of the fractured modes were mixed or interface failures after 24 h of water storage, and the mixed failure increased after six month of water storage. In the 0. 2%, 2% and 20% chlorhexidine treated group, most of the failure was found at the top of hybrid layer, while in the 0. 02% group, it was found in the base part of hybrid layer. Conclusions Chlorhexidine could increase the bonding durability of resin and dentine. Higher than 0. 2%, concentration of chlorhexidine couldn't improve bonding durability.

Key words: 
Dentin; Chlorhexidine; Tensile strength; Bond

Effect of concentration of chlorhexidine on bonding durability of dentine and resin

Objective To investigate,in vitro,the effect of cathepsins specific inhibitor N-(transepoxysuccinyl)-L-leucine 4-guanidinobutylamide (E-64) on dental endogenous cathepsins and to find its most effective molarity to elevate dentin-resin bonding durability.Methods Fifty recently extracted human third molars were divided into five groups according to random number table,and treated with different molarity of E-64 as follow:0,2.5,5.0,10.0 and 20.0 μmol/L.The group 0 μmol/L was control group.Then 20 specimens of dentin-resin composite were fabricated in each group.Half of the specimens were tested after 24 h water storage (37 ℃) and the other half were tested after 90 days water storage (37 ℃) followed by 3000 cycles'thermocyling(5-55 ℃) as aging treatment.Fractured specimens were analyzed using scanning electron microscopy (SEM).Results After 24 h water storage,no significant differences were found in micro-tensile bond strength(μTBS) of samples between different groups (P ＞ 0.05).However,after ageing treatment,μTBS of the samples in group 2.5,5.0,10.0 and 20.0 μmol/L [(18.7 ±2.7),(20.8 ±3.4),(18.3 ± 2.8) and (19.1 ± 2.7) MPa] were significantly higher than that in group 0 μmol/L [(15.1 ± 3.0) MPa] (P ＜ 0.05).Only in the group 5.0 μmol/L no significant difference was found between the original and the decreased value of μTBS(P ＞ 0.05),while the μTBS in other groups decreased significantly after aging treatment(P ＜ 0.05).Failure types were almost adhesive and mixed types.Collagens in hybrid layer were less degraded in the groups using E-64 after aging treatment than control group.Conclusions E-64 was effective on inhibiting cathepsins activity in dentin,and induced less collagens degradation in smear layer for better dentin-resin bond durability.

Key words: 
Cathepsins ;  Enzyme Inhibitors ;  Dentin-bonding agents

Guo-bin Liang

Papers

Long-lasting renewable antibacterial porous polymeric coatings enable titanium biomaterials to prevent and treat peri-implant infection

Effects of acid etching and adhesive treatments on host-derived cysteine cathepsin activity in dentin.

Effect of concentration of chlorhexidine on bonding durability of dentine and resin

[Effect of different molarity cathepsins specific inhibitor E-64 on dentin-resin bonding durability].