Dentin can be described as a biological composite with collagen matrix embedded with nanosized hydroxyapatite mineral crystallites. Matrix metalloproteinases (MMPs) and cysteine cathepsins are ...families of endopeptidases. Enzymes of both families are present in dentin and collectively capable of degrading virtually all extracellular matrix components. This review describes these enzymes and their presence in dentin, mainly focusing on their role in dentin caries pathogenesis and loss of collagen in the adhesive hybrid layer under composite restorations. MMPs and cysteine cathepsins present in saliva, mineralized dentin, and/or dentinal fluid may affect the dentin caries process at the early phases of demineralization. Changes in collagen and noncollagenous protein structure may participate in observed decreases in mechanical properties of caries-affected dentin and reduce the ability of caries-affected dentin to remineralize. These endogenous enzymes also remain entrapped within the hybrid layer during the resin infiltration process, and the acidic bonding agents themselves (irrespective of whether they are etch-and-rinse or self-etch) can activate these endogenous protease proforms. Since resin impregnation is frequently incomplete, denuded collagen matrices associated with free water (which serves as a collagen cleavage reagent for these endogenous hydrolase enzymes) can be enzymatically disrupted, finally contributing to the degradation of the hybrid layer. There are multiple in vitro and in vivo reports showing that the longevity of the adhesive interface is increased when nonspecific enzyme-inhibiting strategies are used. Different chemicals (i.e., chlorhexidine, galardin, and benzalkonium chloride) or collagen cross-linker agents have been successfully employed as therapeutic primers in the bonding procedure. In addition, the incorporation of enzyme inhibitors (i.e., quaternary ammonium methacrylates) into the resin blends has been recently promoted. This review will describe MMP functions in caries and hybrid layer degradation and explore the potential therapeutic role of MMP inhibitors for the development of improved intervention strategies for MMP-related oral diseases.
The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin ...components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding.
We show the feasibility of a real‐time estimation of waveforms and coseismic displacements, within a few centimeters in accuracy, with a stand‐alone dual‐frequency Global Positioning System (GPS) ...receiver using a so‐called “variometric” approach. The approach is based on time single‐differences of carrier phase observations collected at a high‐rate (1 Hz or more) using a stand‐alone receiver, and on standard GPS broadcast products (orbits and clocks), which are ancillary information routinely available in real time. In the approach, first, the time series of epoch‐by‐epoch displacements are estimated. Then, provided that the collected observations are continuous, they can be summed over the interval (limited to a few minutes) over which an earthquake occurs. Since epoch‐by‐epoch displacements divided by the interval between consecutive epochs are essentially equal to the epoch‐by‐epoch velocities, this is equivalent to saying that we are using the GPS receiver as a velocimeter. Estimation biases, due to the possible mismodeling of various intervening effects (such as multipath, residual clock errors, orbit errors, and atmospheric errors), accumulate over time and display their signature as a trend in coseismic displacements. The trend can be considered linear and easily removed, at least for short intervals. Since the proposed approach (named VADASE (Variometric Approach for Displacements Analysis Stand‐alone Engine)) does not require either additional technological complexity or a centralized data analysis, in principle it can be embedded into GPS receiver firmware, thereby providing a significant contribution to tsunami warning and other hazard assessment systems. After a preliminary test using a simulated example, the effectiveness of this approach was proven using real data. We analyzed the 1 Hz GPS data recorded by the International Global Navigation Satellite Systems Service station BREW during the Denali Fault, Alaska, earthquake (Mw 7.9, 3 November, 2002, 22:12:41 UTC), as well as the 5 Hz data collected by some of the stations of the University NAVSTAR Consortium‐Plate Boundary Observatory network and the California Real Time Network during the Baja California, Mexico, earthquake (Mw 7.2, 4 April, 2010, 22:40:42 UTC). Comparisons of the results obtained using VADASE, as well as other already well‐established approaches, displayed agreement to within a few centimeters.
Key Points
RT GPS‐based coseismic displacements estimation at few cm accuracy is shown
The proposed strategy can be embedded in the GPS receiver firmware
It is useful for RT earthquakes source modeling and tsunami early‐warning system
Progress in Dental Adhesive Materials Cadenaro, M.; Josic, U.; Maravić, T. ...
Journal of Dental Research,
03/2023, Letnik:
102, Številka:
3
Book Review, Journal Article
Recenzirano
There have been significant advances in adhesive dentistry in recent decades, with efforts being made to improve the mechanical and bonding properties of resin-based dental adhesive materials. ...Various attempts have been made to achieve versatility, introducing functional monomers and silanes into the materials’ composition to enable the chemical reaction with tooth structure and restorative materials and a multimode use. The novel adhesive materials also tend to be simpler in terms of clinical use, requiring reduced number of steps, making them less technique sensitive. However, these materials must also be reliable and have a long-lasting bond with different substrates. In order to fulfill these arduous tasks, different chemical constituents and different techniques are continuously being developed and introduced into dental adhesive materials. This critical review aims to discuss the concepts behind novel monomers, bioactive molecules, and alternative techniques recently implemented in adhesive dentistry. Incorporating monomers that are more resistant to hydrolytic degradation and functional monomers that enhance the micromechanical retention and improve chemical interactions between adhesive resin materials and various substrates improved the performance of adhesive materials. The current trend is to blend bioactive molecules into adhesive materials to enhance the mechanical properties and prevent endogenous enzymatic degradation of the dental substrate, thus ensuring the longevity of resin–dentin bonds. Moreover, alternative etching materials and techniques have been developed to address the drawbacks of phosphoric acid dentin etching. Altogether, we are witnessing a dynamic era in adhesive dentistry, with advancements aiming to bring us closer to simple and reliable bonding. However, simplification and novelty should not be achieved at the expense of material properties.
Antibiotics in Endodontics: a review Segura‐Egea, J. J.; Gould, K.; Şen, B. Hakan ...
International endodontic journal,
December 2017, Letnik:
50, Številka:
12
Journal Article
Recenzirano
Odprti dostop
The overuse of antibiotics and the emergence of antibiotic‐resistant bacterial strains is a global concern. This concern is also of importance in terms of the oral microbiota and the use of ...antibiotics to deal with oral and dental infections. The aim of this paper was to review the current literature on the indications and use of antibiotics and to make recommendations for their prescription in endodontic patients. Odontogenic infections, including endodontic infections, are polymicrobial, and in most cases, the prescription of antibiotics is empirical. This has led to the increasing use of broad‐spectrum antibiotics even in cases where antibiotics are not indicated, such as symptomatic irreversible pulpitis, necrotic pulps and localized acute apical abscesses. In case of discrete and localized swelling, the primary aim is to achieve drainage without additional antibiotics. Adjunctive antibiotic treatment may be necessary in the prevention of the spread of infection, in acute apical abscesses with systemic involvement and in progressive and persistent infections. Medically compromised patients are more susceptible to complication arising from odontogenic infections and antimicrobials have a more specific role in their treatment. Therefore, antibiotics should be considered in patients having systemic diseases with compromised immunity or in patients with a localized congenital or acquired altered defence capacity, such as patients with infective endocarditis, prosthetic cardiac valves or recent prosthetic joint replacement. Penicillin VK, possibly combined with metronidazole to cover anaerobic strains, is still effective in most cases. However, amoxicillin (alone or together with clavulanic acid) is recommended because of better absorption and lower risk of side effects. In case of confirmed penicillin allergy, lincosamides such as clindamycin are the drug of choice.
This position statement represents a consensus of an expert committee convened by the European Society of Endodontology (ESE) on Antibiotics in Endodontics. The statement is based on current ...scientific evidence as well as the expertise of the committee. The goal is to provide dentists and other healthcare workers with evidence‐based criteria for when to use antibiotics in the treatment of endodontic infections, traumatic injuries of the teeth, revascularization procedures in immature teeth with pulp necrosis, and in prophylaxis for medically compromised patients. It also highlights the role that dentists and others can play in preventing the overuse of antibiotics. A recent review article provides the basis for this position statement and more detailed background information (International Endodontic Journal, 2017, https://doi.org/10.1111/iej.12741). Given the dynamic nature of research in this area, this position statement will be updated at appropriate intervals.
Host-derived proteases have been reported to degrade the collagen matrix of incompletely-resin-infiltrated dentin. This study tested the hypothesis that interfacial degradation of resin-dentin bonds ...may be prevented or delayed by the application of chlorhexidine (CHX), a matrix metalloproteinase inhibitor, to dentin after phosphoric acid-etching. Contralateral pairs of resin-bonded Class I restorations in non-carious third molars were kept under intra-oral function for 14 months. Preservation of resin-dentin bonds was assessed by microtensile bond strength tests and TEM examination. In vivo bond strength remained stable in the CHX-treated specimens, while bond strength decreased significantly in control teeth. Resin-infiltrated dentin in CHX-treated specimens exhibited normal structural integrity of the collagen network. Conversely, progressive disintegration of the fibrillar network was identified in control specimens. Auto-degradation of collagen matrices can occur in resin-infiltrated dentin, but may be prevented by the application of a synthetic protease inhibitor, such as chlorhexidine.
Abstract Objectives This study evaluated the endogenous matrix metalloproteinase (MMP) activity of demineralized dentin matrix following 1 or 5 min pretreatment by various collagen crosslinkers. ...Generic MMP activity assay, total protein analysis, in situ zymography, gelatin zymography and multiplex bead technology were used to evaluate matrix-bound MMP activity. Methods Six different crosslinkers; glutaraldehyde, riboflavin/UVA, riboflavin-5-monophospate/UVA, sumac berry extract, grape seed extract, and curcumin were used. Demineralized dentin beams were pretreated with respective crosslinkers for 1 or 5 min. Demineralized dentin beams with no crosslinker pretreatment served as control. The reduction in the total activity of dentin matrices were measured using generic MMP activity assay. Dentin slabs were used for in situ zymography and evaluated by using hydrolysis of self-quenched fluorescein-conjugated gelatin under confocal microscopy. Dentin beam extracts were used for total protein assay and multiplex analysis and powder extracts were used for gelatin zymography. Results MMP activity in crosslinker pretreated samples decreased significantly between 21% and 70%, whereas untreated control samples’ activity increased up to 84%. Zymograms confirmed a decrease in the gelatinolytic activity and in the amount of extractable total protein content. Multiplex analysis of extracts of crosslinker-treated dentin showed a reduction in the MMP-8, MMP-2 and MMP-9 release. Significance The result of this work suggests that the effect of the crosslinkers is source-dependent. The use of crosslinkers for as little as 1 min on demineralized dentin can inactivate the endogenous protease activity of dentin matrices.
Auto-degradation of collagen matrices occurs within hybrid layers created by contemporary dentin bonding systems, by the slow action of host-derived matrix metalloproteinases (MMPs). This study ...tested the null hypothesis that there are no differences in the activities of MMP-2 and -9 after treatment with different etch-and-rinse or self-etch adhesives. Tested adhesives were: Adper Scotchbond 1XT (3M ESPE), PQ1 (Ultradent), Peak LC (Ultradent), Optibond Solo Plus (Kerr), Prime&Bond NT (Dentsply) (all 2-step etch-and-rinse adhesives), and Adper Easy Bond (3M ESPE), Tri-S (Kuraray), and Xeno-V (Dentsply) (1-step self-etch adhesives). MMP-2 and -9 activities were quantified in adhesive-treated dentin powder by means of an activity assay and gelatin zymography. MMP-2 and MMP-9 activities were found after treatment with all of the simplified etch-and-rinse and self-etch adhesives; however, the activation was adhesive-dependent. It is concluded that all two-step etch-and-rinse and the one-step self-etch adhesives tested can activate endogenous MMP-2 and MMP-9 in human dentin. These results support the role of endogenous MMPs in the degradation of hybrid layers created by these adhesives.
This study determined if dentin proteases are denatured by phosphoric acid (PA) used in etch-and-rinse dentin adhesives. Dentin beams were completely demineralized with EDTA for 30 days. We ...“acid-etched” experimental groups by exposing the demineralized dentin beams to 1, 10, or 37 mass% PA for 15 sec or 15 min. Control beams were not exposed to PA but were incubated in simulated body fluid for 3 days to assay their total endogenous telopeptidase activity, by their ability to solubilize C-terminal crosslinked telopeptides ICTP and CTX from insoluble dentin collagen. Control beams released 6.1 ± 0.8 ng ICTP and 0.6 ± 0.1 ng CTX/mg dry-wt/3 days. Positive control beams pre-incubated in p-aminophenylmercuric acetate, a compound known to activate proMMPs, released about the same amount of ICTP peptides, but released significantly less CTX. Beams immersed in 1, 10, or 37 mass% PA for 15 sec or 15 min released amounts of ICTP and CTX similar to that released by the controls (p > 0.05). Beams incubated in galardin, an MMP inhibitor, or E-64, a cathepsin inhibitor, blocked most of the release of ICTP and CTX, respectively. It is concluded that PA does not denature endogenous MMP and cathepsin activities of dentin matrices.
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