Artificial intelligence (AI) is a technology that utilizes machines to mimic intelligent human behavior. To appreciate human-technology interaction in the clinical setting, augmented intelligence has ...been proposed as a cognitive extension of AI in health care, emphasizing its assistive and supplementary role to medical professionals. While truly autonomous medical robotic systems are still beyond reach, the virtual component of AI, known as software-type algorithms, is the main component used in dentistry. Because of their powerful capabilities in data analysis, these virtual algorithms are expected to improve the accuracy and efficacy of dental diagnosis, provide visualized anatomic guidance for treatment, simulate and evaluate prospective results, and project the occurrence and prognosis of oral diseases. Potential obstacles in contemporary algorithms that prevent routine implementation of AI include the lack of data curation, sharing, and readability; the inability to illustrate the inner decision-making process; the insufficient power of classical computing; and the neglect of ethical principles in the design of AI frameworks. It is necessary to maintain a proactive attitude toward AI to ensure its affirmative development and promote human-technology rapport to revolutionize dental practice. The present review outlines the progress and potential dental applications of AI in medical-aided diagnosis, treatment, and disease prediction and discusses their data limitations, interpretability, computing power, and ethical considerations, as well as their impact on dentists, with the objective of creating a backdrop for future research in this rapidly expanding arena.
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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.
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Matrix metalloproteinases (MMPs) are important in dentinal caries, and analysis of recent data demonstrates the presence of other collagen-degrading enzymes, cysteine cathepsins, in human dentin. ...This study aimed to examine the presence, source, and activity of cysteine cathepsins in human caries. Cathepsin B was detected with immunostaining. Saliva and dentin cysteine cathepsin and MMP activities on caries lesions were analyzed spectrofluorometrically. Immunostaining demonstrated stronger cathepsins B in carious than in healthy dentin. In carious dentin, cysteine cathepsin activity increased with increasing depth and age in chronic lesions, but decreased with age in active lesions. MMP activity decreased with age in both active and chronic lesions. Salivary MMP activities were higher in patients with active than chronic lesions and with increasing lesion depth, while cysteine cathepsin activities showed no differences. The results indicate that, along with MMPs, cysteine cathepsins are important, especially in active and deep caries.
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The long-term effectiveness of chlorhexidine as a matrix metalloproteinase (MMP) inhibitor may be compromised when water is incompletely removed during dentin bonding. This study challenged this ...anti-bond degradation strategy by testing the null hypothesis that wet-bonding with water or ethanol has no effect on the effectiveness of chlorhexidine in preventing hybrid layer degradation over an 18-month period. Acid-etched dentin was bonded under pulpal pressure simulation with Scotchbond MP and Single Bond 2, with water wet-bonding or with a hydrophobic adhesive with ethanol wet-bonding, with or without pre-treatment with chlorhexidine diacetate (CHD). Resin-dentin beams were prepared for bond strength and TEM evaluation after 24 hrs and after aging in artificial saliva for 9 and 18 mos. Bonds made to ethanol-saturated dentin did not change over time with preservation of hybrid layer integrity. Bonds made to CHD pre-treated acid-etched dentin with commercial adhesives with water wet-bonding were preserved after 9 mos but not after 18 mos, with severe hybrid layer degradation. The results led to rejection of the null hypothesis and highlight the concept of biomimetic water replacement from the collagen intrafibrillar compartments as the ultimate goal in extending the longevity of resin-dentin bonds.
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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.
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The use of TEGDMA as a diluent comonomer in the formulation of hydrophobic adhesives for ethanol wet-bonding is a concern, due to its leaching potential, higher water sorption, and ...bio-incompatibility. This study tested the hypothesis that hydrophobic bonding to acid-etched dentin may be accomplished with the use of ethanol-solvated BisGMA only. Phosphoric-acid-etched, oxalate-occluded, deep coronal dentin bonded under 20 cm water pressure with experimental BisGMA adhesives by ethanol wet-bonding exhibited tensile strengths that were not significantly different from that achieved with OptiBond FL bonded according to the manufacturer-recommended protocol, with similar acid-/base-resistant hybrid layers, resin tags, and nanoleakage distribution. Ethanol replacement of water-saturated dentin produced wider interfibrillar spaces, more extensive shrinkage of the collagen fibrils, and narrower hybrid layers. Experimental BisGMA adhesives provide the proof of concept that relatively hydrophobic resins may be coupled to acid-etched dentin by increasing its hydrophobic characteristics via ethanol replacement. They should be further optimized before clinical application.
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Matrix metalloproteinases (MMPs) bound to dentin contribute to the progressive degradation of collagen fibrils in hybrid layers created by dentin adhesives. This study evaluated the MMP-inhibiting ...potential of quaternary ammonium methacrylates (QAMs), with soluble rhMMP-9 and a matrix-bound endogenous MMP model. Six different QAMs were initially screened by a rhMMP-9 colorimetric assay. For the matrix-bound endogenous MMPs, we aged demineralized dentin beams for 30 days in calcium- and zinc-containing media (CM; control), chlorhexidine, or QAMs in CM to determine the changes in dry mass loss and solubilization of collagen peptides against baseline levels. The inhibitory effects of QAMs on soluble rhMMP-9 varied between 34 and 100%. Beams incubated in CM showed a 29% decrease in dry mass (p < 0.05), whereas beams incubated with QAMs showed only 0.2%-6% loss of dry mass. Significantly more solubilized collagen was detected from beams incubated in CM (p < 0.05). It is concluded that QAMs exhibited dentin MMP inhibition comparable with that of chlorhexidine, but required higher concentrations.
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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.
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Degradation of denuded collagen within adhesive resin-infiltrated dentin is a pertinent problem in dentin bonding. A biomimetic remineralization scheme that incorporates non-classic crystallization ...pathways of fluidic amorphous nanoprecursors and mesoscopic transformation has been successful in remineralizing resin-free, acid-etched dentin, with evidence of intrafibrillar and interfibrillar remineralization. This study tested the hypothesis that biomimetic remineralization provides a means for remineralizing incompletely infiltrated resin-dentin interfaces created by etch-and-rinse adhesives. The remineralization medium consists of a Portland cement/simulated body fluid that includes polyacrylic acid and polyvinylphosphonic acid biomimetic analogs for amorphous calcium phosphate dimension regulation and collagen targeting. Both interfibrillar and intrafibrillar apatites became readily discernible within the hybrid layers after 2–4 months. In addition, intra-resin apatite clusters were deposited within the porosities of the adhesive resin matrices. The biomimetic remineralization scheme provides a proof-of-concept for the adoption of nanotechnology as an alternative strategy to extend the longevity of resin-dentin bonds.
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The concept of extrafibrillar demineralization involves selective removal of apatite crystallites from the extrafibrillar spaces of mineralized dentin without disturbing the intrafibrillar minerals ...within collagen. This helps avoiding activation of endogenous proteases and enables air-drying of partially demineralized dentin without causing collapse of completely demineralized collagen matrix that adversely affects resin infiltration. The objective of the present study was to evaluate the potential of quaternized carboxymethyl chitosan (QCMC)–based extrafibrillar demineralization in improving resin–dentin bond durability. Isothermal titration calorimetry indicated that QCMC synthesized by quaternization of O-carboxymethyl chitosan had moderate affinity for Ca2+ (binding constant: 8.9 × 104 M−1). Wet and dry bonding with the QCMC-based demineralization produced tensile bond strengths equivalent to the phosphoric acid (H3PO4)–based etch-and-rinse technique. Those bond strengths were maintained after thermocycling. Amide I and PO43− mappings of QCMC-conditioned dentin were performed with atomic force microscope–infrared spectroscopy (AFM-IR). Whereas H3PO4-etched dentin exhibited an extensive reduction in PO43− signals corresponding to apatite depletion, QCMC-conditioned dentin showed scattered dark areas and bright PO43− streak signals. The latter were consistent with areas identified as collagen fibrils in the amide I mapping and were suggestive of the presence of intrafibrillar minerals in QCMC-conditioned dentin. Young’s modulus mapping of QCMC-demineralized dentin obtained by AFM-based amplitude modulation–frequency modulation recorded moduli that were the same order of magnitude as those in mineralized dentin and at least 1 order higher than H3PO4-etched dentin. In situ zymography of the gelatinolytic activity within hybrid layers created with QCMC conditioning revealed extremely low signals before and after thermocycling, compared with H3PO4-etched dentin for both wet and dry bonding. Confocal laser scanning microscopy identified the antibacterial potential of QCMC against Streptococcus mutans and Enterococcus faecalis biofilms. Taken together, the QCMC-based demineralization retains intrafibrillar minerals, preserves the elastic modulus of collagen fibrils, reduces endogenous proteolytic activity, and inhibits bacteria biofilms to extend dentin bond durability.
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