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Journal of Dental Research Feb 2015Dentin can be described as a biological composite with collagen matrix embedded with nanosized hydroxyapatite mineral crystallites. Matrix metalloproteinases (MMPs) and... (Review)
Review
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.
Topics: Cathepsins; Collagen; Dental Bonding; Dental Caries; Dental Materials; Dentin; Disease Progression; Humans; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases
PubMed: 25535202
DOI: 10.1177/0022034514562833 -
Journal of Biomechanics Aug 2022Investigations into teeth mechanical properties provide insight into physiological functions and pathological changes. This study sought to 1) quantify the spatial...
Investigations into teeth mechanical properties provide insight into physiological functions and pathological changes. This study sought to 1) quantify the spatial distribution of elastic modulus, hardness and the microstructural features of dog dentin and to 2) investigate quantitative relationships between the mechanical properties and the complex microstructure of dog dentin. Maxillary canine teeth of 10 mature dogs were sectioned in the transverse and vertical planes, then tested using nanoindentation and scanning electron microscopy (SEM). Microstructural features (dentin area fraction and dentinal tubule density) and mechanical properties (elastic modulus and hardness) were quantified. Results demonstrated significant anisotropy and spatial variation in elastic modulus, hardness, dentin area fraction and tubule density. These spatial variations adhered to a consistent distribution pattern; hardness, elastic modulus and dentin area fraction generally decreased from superficial to deep dentin and from crown tip to base; tubule density generally increased from superficial to deep dentin. Poor to moderate correlations between microstructural features and mechanical properties (R = 0.032-0.466) were determined. The results of this study suggest that the other constituents may contribute to the mechanical behavior of mammalian dentin. Our results also present several remaining opportunities for further investigation into the roles of organic components (e.g., collagen) and mineral content on dentin mechanical behavior.
Topics: Animals; Dentin; Dogs; Elastic Modulus; Hardness; Mammals; Microscopy, Electron, Scanning; Structure-Activity Relationship; Tooth
PubMed: 35834939
DOI: 10.1016/j.jbiomech.2022.111218 -
Dental Materials : Official Publication... Jul 2022The conventional radiotherapy protocol to treat head-and-neck cancer is usually followed by tooth-decay onset. Radiation impact on mineralized tooth structures is not... (Review)
Review
OBJECTIVES
The conventional radiotherapy protocol to treat head-and-neck cancer is usually followed by tooth-decay onset. Radiation impact on mineralized tooth structures is not well-understood. This systematic review aimed to collect the recorded effects of therapeutic radiation on tooth chemical, structural and mechanical properties, in relation with their means of investigation.
DATA
Systematic search (January 01 2012 - September 30 2021) terms were "Radiotherapy", "Radiation effects", "Dental enamel", "Dentin", "Human" and "Radiotherapy" NOT "Laser".
SOURCES
PubMed, DOSS and Embase databases were searched.
STUDY SELECTION
Selected studies compared dental enamel, coronal and root dentin properties before and after in vitro or in vivo irradiation up to 80 Gy.
RESULTS
The systematic search identified 353 different articles, with 28 satisfying inclusion criteria. Their reference lists provided two more. Twenty-two studies evaluated dental enamel evolution, nine assessed coronal dentin and eight concerned root dentin. Coronal and root dentin results indicate a major impact of the radiation on their organic matrix. Dental enamel's chemical properties are less modified. Enamel and root dentin's hardness are decreased by therapeutic radiation, but no consensus arises for coronal dentin.
CONCLUSIONS
Our findings revealed some interesting information about enzymatic degradation mechanisms of dentin organic matrix and highlighted that dental hard-tissue characterization requires highly specific expertise in materials science. That scientific knowledge is necessary to design suitable protocols, adequately analyze the obtained data, and, thus, provide relevant conclusions.
CLINICAL SIGNIFICANCE STATEMENT
Better knowledge and understanding of the mechanisms involved in the degradation of enamel and dentin would enable development of new preventive and therapeutic methods for improved medical care of patients undergoing radiotherapy.
Topics: Dental Caries; Dental Enamel; Dentin; Head and Neck Neoplasms; Humans; Radiation Injuries; Tooth
PubMed: 35570008
DOI: 10.1016/j.dental.2022.04.014 -
Gerodontology Jun 2018This study aimed to identify the changes in the time-dependent deformation response of coronal dentin with ageing and its relationship with changes in chemical...
OBJECTIVE
This study aimed to identify the changes in the time-dependent deformation response of coronal dentin with ageing and its relationship with changes in chemical composition.
BACKGROUND
The structural behaviour of dentin with ageing is affected by changes in the density and diameter of its dentinal tubules (ie porosity), as well as changes in chemical composition throughout the tooth. However, little is known about the time-dependent deformation behaviour of aged dentin and the importance of its hierarchical structure and variations in chemical composition.
MATERIALS AND METHODS
The spherical indentation response of aged coronal dentin was analysed in the outer, middle and inner regions, and its time-dependent deformation response was modelled in terms of its microstructure and chemical composition using a model recently proposed for young dentin.
RESULTS
The viscous deformation behaviour of aged dentin followed a power-law response with a decrease in the stress exponent when compared to young dentin. These results can be explained by cross-linking of the collagen present in the tissue.
CONCLUSION
A decrease in the deformation ability of aged dentin was found. This behaviour could be a result of a dissolution process and reprecipitation of the minerals present in intertubular dentin into the dentinal tubules.
Topics: Age Factors; Aged; Aged, 80 and over; Aging; Collagen; Dental Stress Analysis; Dentin; Female; Humans; Male; Middle Aged; Spectrum Analysis, Raman; Tooth Crown
PubMed: 29368792
DOI: 10.1111/ger.12321 -
ACS Biomaterials Science & Engineering Jun 2020Biomineralization has intrigued researchers for decades. Although mineralization of type I collagen has been universally investigated, this process remains a great...
Biomineralization has intrigued researchers for decades. Although mineralization of type I collagen has been universally investigated, this process remains a great challenge due to the lack of mechanistic understanding of the roles of biomolecules. In our study, dentine was successfully repaired using the biomolecule polydopamine (PDA), and the remineralized dentine exhibited mechanical properties comparable to those of natural dentine. Detailed analyses of the collagen mineralization process facilitated by PDA showed that PDA can promote intrafibrillar mineralization with a decreased heterogeneous nucleation barrier for hydroxyapatite (HAP) by reducing the interfacial energy between collagen fibrils and amorphous calcium phosphate (ACP), resulting in the conversion of an increasing amount of nanoprecursors into collagen fibrils. The present work highlights the importance of interfacial control in dentine remineralization and provides profound insight into the regulatory effect of biomolecules in collagen mineralization as well as the clinical application of dentine restoration.
Topics: Collagen; Dentin; Indoles; Polymers
PubMed: 33463183
DOI: 10.1021/acsbiomaterials.0c00035 -
Clinical Oral Investigations Mar 2018The objective of this study was to evaluate the biomechanical properties of dentin and the microtensile bond strength (μTBS) performed before or after radiotherapy (RT).
OBJECTIVES
The objective of this study was to evaluate the biomechanical properties of dentin and the microtensile bond strength (μTBS) performed before or after radiotherapy (RT).
MATERIAL AND METHODS
Dentin chemical composition (infrared spectroscopy-FTIR), SEM images, and mechanical properties (Vickers microhardness-VHN and elastic modulus-E) were evaluated comparing no irradiated and irradiate dentin (n = 5). RT was defined by application of 72 Gy (1.8 Gy daily, 5 days per week, during 8 weeks) with sample immersed in distilled water. μTBS evaluated three groups (n = 10): NI-no irradiated; IB-irradiation before restoration; and IA-irradiation after restoration. Resin-dentin sticks (1.0 mm) were obtained and submitted to μTBS. Analysis of the bonding interface was made by confocal microscopy.
RESULTS
After RT, percentage ratio of FTIR analysis showed increased absorption for all bands. SEM image showed a disorganized dentin structure. Two-way ANOVA showed increased VHN (p = 0.005) and decreased E (p < 0.001). For μTBS, one-way ANOVA and Duncan test showed significant differences among groups (p = 0.018). IB group presented the lowest bond strength values.
CONCLUSIONS
RT alters the absorption bands and SEM images showed a disorganization of the dentin structure. Mechanical properties were changed with increased VHN and decreased E. μTBS was affected by the radiotherapy and restoration period (before or after).
CLINICAL RELEVANCE
RT causes changes that contribute to increased risk of tooth decay. Restorative treatments can be performed using adhesive procedures, but it is preferable to be performed before of the irradiation protocol, to guarantee better adhesive properties to restoration.
Topics: Dental Stress Analysis; Dentin; Dentin-Bonding Agents; Elastic Modulus; Hardness Tests; Humans; In Vitro Techniques; Materials Testing; Microscopy, Confocal; Microscopy, Electron, Scanning; Molar, Third; Resin Cements; Spectrophotometry, Infrared; Surface Properties; Tensile Strength
PubMed: 28776096
DOI: 10.1007/s00784-017-2165-4 -
Journal of Dental Research Sep 2021Glass ionomer cements (GICs) are considered the material of choice for restoration of root carious lesions (RCLs). When bonding to demineralized dentin, the collapse of...
Glass ionomer cements (GICs) are considered the material of choice for restoration of root carious lesions (RCLs). When bonding to demineralized dentin, the collapse of dentinal collagen during restorative treatment may pose challenges. Considering its acidic nature and collagen biomodification effects, proanthocyanidin (PAC) could be potentially used as a dentin conditioner to remove the smear layer while simultaneously acting to biomodify the dentinal collagen involved in the bonding interface. In this study, 6.5% w/v PAC was used as a conditioner for sound (SD) and laboratory demineralized (DD) root dentin before bonding to resin-modified GIC (FII), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified GIC (FVII), or a high-viscosity GIC (FIX). Root dentin conditioned with deionized distilled water (DDW) or polyacrylic acid (PAA) served as controls. Results indicated FII showed higher shear bond strength (SBS) on SD than the other 2 GICs, especially in PAA-conditioned samples; FIX showed significantly higher SBS than FII and FVII on PAA- or PAC-conditioned DD. In each category of GIC, PAA and PAC did not have a significant influence on SBS in most cases compared to DDW except for a significant decrease in PAC-conditioned SD bonded to FII and a significant increase in PAA-conditioned DD bonded to FIX. The bonding interface between GIC and SD was generally more resistant to the acid-base challenge than DD. Although the alterations in failure modes indicated a compromised interfacial interaction between GICs and PAC-treated root dentin, biomodification effects of PAC on dentin were observed from Raman microspectroscopy analysis in terms of the changes in mineral-to-matrix ratio and hydroxyproline-to-proline ratio of dentin adjacent to the bonding interface, especially of DD. Results from this study also indicated the possibility of using in situ characterization such as Raman microspectroscopy as a complementary approach to SBS test to investigate the integrity of the bonding interface.
Topics: Dental Bonding; Dentin; Dentin-Bonding Agents; Glass Ionomer Cements; Materials Testing; Proanthocyanidins; Resin Cements
PubMed: 34261333
DOI: 10.1177/00220345211018182 -
BMC Oral Health Apr 2024The stability of resin-dentin interfaces is still highly questionable. The aim of this study was to evaluate the effect of Salvadora persica on resin-dentin bond...
BACKGROUND
The stability of resin-dentin interfaces is still highly questionable. The aim of this study was to evaluate the effect of Salvadora persica on resin-dentin bond durability.
MATERIALS AND METHODS
Extracted human third molars were used to provide mid-coronal dentin, which was treated with 20% Salvadora persica extract for 1 min after acid-etching. Microtensile bond strength and interfacial nanoleakage were evaluated after 24 h and 6 months. A three-point flexure test was used to measure the stiffness of completely demineralized dentin sticks before and after treatment with Salvadora persica extract. The hydroxyproline release test was also used to measure collagen degradation by endogenous dentin proteases. Statistical analysis was performed using two-way ANOVA followed by post hoc Bonferroni test and unpaired t-test. P-values < 0.05 were considered statistically significant.
RESULTS
The use of Salvadora persica as an additional primer with etch-and-rinse adhesive did not affect the immediate bond strengths and nanoleakage (p > 0.05). After 6 months, the bond strength of the control group decreased (p = 0.007), and nanoleakage increased (p = 0.006), while Salvadora persica group showed no significant difference in bond strength and nanoleakage compared to their 24 h groups (p > 0.05). Salvadora persica increased dentin stiffness and decreased collagen degradation (p < 0.001) compared to their controls.
CONCLUSION
Salvadora persica extract pretreatment of acid-etched dentin preserved resin-dentin bonded interface for 6 months.
CLINICAL SIGNIFICANCE
Durability of resin-dentin bonded interfaces is still highly questionable. Endogenous dentinal matrix metalloproteinases play an important role in degradation of dentinal collagen within such interfaces. Salvadora persica may preserve resin-dentin interfaces for longer periods of time contributing to greater clinical success and longevity of resin composite restorations.
Topics: Humans; Dentin; Tensile Strength; Plant Extracts; Dental Bonding; Dental Leakage; Salvadoraceae; Acid Etching, Dental; Collagen; Dentin-Bonding Agents; Materials Testing; Hydroxyproline; Dental Stress Analysis; Composite Resins; Time Factors; Resin Cements
PubMed: 38684974
DOI: 10.1186/s12903-024-04244-3 -
Dental Materials : Official Publication... Jan 2021The purpose of this study was to develop a new device that can improve the effect of desensitizer using shockwaves and to verify its efficacy.
OBJECTIVES
The purpose of this study was to develop a new device that can improve the effect of desensitizer using shockwaves and to verify its efficacy.
METHODS
A micro-shockwave generator was developed using a piezoelectric actuator (PIA-1000, piezosystem jena GmbH, Jena, Germany), an Arduino Uno microcontroller (Arduino, Torino, Italy), and a high voltage pulser (HVP-1000, piezosystem jena GmbH) at 700 V (400 A) and 100 μs. The occlusal surfaces of 20 extracted human upper and lower third molars without caries or restoration were reduced to expose the occlusal dentin, and the prepared occlusal surfaces were acid-etched with 32% phosphoric acid to remove the smear layer. The tooth specimens were connected to a fluid flow measurement instrument (nanoFlow, IB SYSTEMS, Seoul, Korea), permeability through dentin via dentinal fluid flow (DFF) was measured for 300 s, and the average DFF rate (Baseline DFF rate) was calculated. A desensitizer (SuperSeal, Phoenix Dental, Fenton, MI, USA) was applied to the acid-etched occlusal dentin surface of 10 randomly selected tooth specimens, left for 10 s, and rubbed with a microbrush for 30 s (Group 1). For the remaining teeth, the desensitizer was applied, and a shockwave (100 μm stroke, 10,000 G) was applied for 10 s (2 shots/s) and rubbed with a microbrush for 30 s (Group 2). After desensitizer application, subsequent DFF was measured for 600 s, and the average DFF rate was calculated (post-application DFF rate). DFF was continuously measured in real-time at 25 ± 0.5 ℃ under a hydrostatic pressure of 25 cm. The percentage reduction in DFF rate after desensitizer application (with or without shockwave) was calculated with respect to baseline DFF rate. Data were analyzed with independent t-test (α = 0.05).
RESULTS
For all tooth specimens, DFF rate decreased after desensitizer application irrespective of the presence of shockwaves. The percentage reduction in DFF rate of SuperSeal with shockwave (Group 2) was 42.8 ± 19.0%, which was significantly higher than the 26.2 ± 13.6% of the SuperSeal only group (Group 1) (p < 0.05).
SIGNIFICANCE
Measurement of DFF change in real-time shows that shockwaves can help reduce dentin permeability beyond that SuperSeal dentin desensitizer produced alone.
Topics: Dentin; Dentin Permeability; Dentin Sensitivity; Humans; Microscopy, Electron, Scanning; Smear Layer
PubMed: 33190860
DOI: 10.1016/j.dental.2020.10.027 -
Dental Materials : Official Publication... Mar 2024Tideglusib has shown great performance in terms of dentin regenerative properties. This study aims to evaluate bonding ability, of demineralized dentin infiltrated with...
OBJECTIVES
Tideglusib has shown great performance in terms of dentin regenerative properties. This study aims to evaluate bonding ability, of demineralized dentin infiltrated with polymeric nanoparticles (NPs) doped with tideglusib (TG) (TG-NPs).
METHODS
Dentin conditioned surfaces were infiltrated with NPs and TG-NPs. Bonded interfaces were created and stored for 24 h and then submitted to mechanical, chemical and thermal challenging. The resin-dentin interface was evaluated through a doubled dye fluorescent technique and a calcium chelator fluorophore under a confocal laser scanning microscopy, and by field emission scanning electron microscopy.
RESULTS
Dentin surfaces treated with TG-NPs and load cycled produced higher bond strength than the rest of the groups. Immersion of dentin specimens treated with undoped-NPs in collagenase solution attained the lowest microtensile bond strength (MTBS) values. Both porosity and nanoleakage decreased when dentin was infiltrated with TG-NPs, that revealed strong signals of xylenol orange stain at both hybrid layer and dentinal tubules. The presence of NPs, in general, inducted the presence of mineralized interfaces after mechanical loading and thermocycling.
CONCLUSIONS
Nanoparticles doped with tideglusib promoted the highest dentin bonding efficacy among groups, as they facilitated the maximum bond strength values with creation of mineral deposits at the hybrid layer and dentinal walls. Tideglusib enabled scarce porosity, nanoleakage and advanced sealing among dentin groups.
SIGNIFICANCE
Doping hydrophilic polymeric NPs with tideglusib, infiltrated in etched dentin represents a reproducible technique to create reparative dentin at the resin-dentin interface, by inducing therapeutic bioactivity.
Topics: Dental Cements; Resin Cements; Glycogen Synthase Kinase 3; Dentin-Bonding Agents; Tensile Strength; Dentin; Microscopy, Electron, Scanning; Dental Bonding; Materials Testing; Thiadiazoles
PubMed: 38114343
DOI: 10.1016/j.dental.2023.12.010