This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were select...This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were selected, including 18 males and 21 females. Forty-eight human maxillary first premolars from orthodontic extractions were chosen to prepare the test models with the dentinal tubule orientations perpendicular and parallel to the bonding substrate. The test models in the vertical and parallel groups were divided into three groups： total-etching with 20% phosphoric acid, total-etching with 35% phosphoric acid and self-etching, with the dentinal tubule surfaces bonded with composite resin blocks in each group. After the standard test models of dentinal tubule-composite resin blocks were placed in distilled water and stored at 37℃ for 24 h, shearing tests were performed using a universal material testing machine at a crosshead speed of 0.5 mm/min. The bond strength values in the vertical group were 19.33＋1.59 MPa for the 20% phosphoric acid group, 21.39±2.34 MPa for the 35% phosphoric acid group, and 16.88±1.54 MPa for the self-etching group. The bond strength values in the parallel group were 24.53±1.99 MPa for the 20% phosphoric acid group, 25.16＋2.88 MPa for the 35% phosphoric acid group, and 20.83±1.99 for the self-etching group. After using same total-etching adhesive, the shear bond strength of the parallel group was higher than that of the vertical group, and the difference was statistically significant （P〈0.05）. Regardless of vertical group or parallel group, the difference in the bond strength value between the total-etching groups and the self-etching group was statistically significant （P〈0.05）. It was concluded that the dentin bonding substrate which was parallel to the direction of the dentin tubule achieved an improved bond strength; the total-etching adhesives achieved higher bond strengths in dentin bond than the self-etching adhesives.展开更多
Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment ...Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm2, 200 J/cm2, 400 J/cm2 and 600 J/cm2, respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively;and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.展开更多
The morpohologic feature of radicular dentin in sensitive and naturally desensitive area was observed with scanning electron microscopy (SEM). Eight specimens were taken from six patients with periodontal diseases. It...The morpohologic feature of radicular dentin in sensitive and naturally desensitive area was observed with scanning electron microscopy (SEM). Eight specimens were taken from six patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hyperoensitive areas was much larger than that in naturally desensitive areas. The results suggest that theie is relationship between dentin moophology and dentin hypersensitivity. In this article, a new dentin bipopsy technique with hollow drill was reported also.展开更多
The aim of this study was to evaluate the dentinal tubule sealing and acid resistance of dentin specimens following the application of calcium phosphate glass powder prior to irradiation with a CO2(carbon dioxide)lase...The aim of this study was to evaluate the dentinal tubule sealing and acid resistance of dentin specimens following the application of calcium phosphate glass powder prior to irradiation with a CO2(carbon dioxide)laser.Dentin models simulating open dentinal tubules were divided into two groups:experimental(calcium phosphate glass slurry applied to the dentin surface)and control(no slurry applied to the surface).All specimens in the experimental group and five specimens in the control group were irradiated with a CO2 laser.The defocused laser beams(0.5 and 1 W)were applied(spot size,5 mm in diameter)from a distance of 20 mm for 10 s.The surfaces and cross-sectional areas of the specimens were examined using an SEM(scanning electron microscope).In addition,the resistance to acid was evaluated in these specimens.The open dentinal tubules in the control groups were sealed following irradiation with the CO2 laser at 0.5 W and 1.0 W.Likewise,sealing of open dentinal tubules was observed in the experimental group after CO2 laser irradiation.The acid resistance of the dentin surface was improved after CO2 laser irradiation;specimens in the experimental group presented with significantly lower amounts of Ca ion release compared to those in the control group.These findings indicate that CO2 laser irradiation alone or after the application of calcium phosphate glass powder can effectively seal the dentinal tubules and alleviate dentin hypersensitivity.展开更多
The morphologic feature of radicular dentin in sensitive and naturally desensitive areas was observed with scanning electron microscopy(SEM). Eight specimens were taken from six-patients with periodontal diseases. It ...The morphologic feature of radicular dentin in sensitive and naturally desensitive areas was observed with scanning electron microscopy(SEM). Eight specimens were taken from six-patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hypersensitive areas was much larger than that in naturally desensitive areas. The results suggest that there is relationship between dentin morphology and dentin hypersensitivity. In this article, a new technique of dentin biopsy with hollow drill was reported also.展开更多
The effects of occlusion of dentinal tubuls Im a Chinese traditional medicine Complex Gao Liang Jiang Paste were evaluated using scanning electron microscope and Oc-clusion of dentinal tubules occurred of after treatm...The effects of occlusion of dentinal tubuls Im a Chinese traditional medicine Complex Gao Liang Jiang Paste were evaluated using scanning electron microscope and Oc-clusion of dentinal tubules occurred of after treatment with the preparation for 5 mm ohstructed after 10 min and complete occlusion after 20 min. In order to get ideal result the be lengthened when the paste is used.展开更多
Effective mineralization of biological structures poses a significant challenge in hard tissue engineering as it necessitates overcoming geometric complexities and multistep biomineralization processes.In this regard,...Effective mineralization of biological structures poses a significant challenge in hard tissue engineering as it necessitates overcoming geometric complexities and multistep biomineralization processes.In this regard,we propose“mineral-in-shell nanoarchitectonics”,inspired by the nanostructure of matrix vesicles,which can influence multiple mineralization pathways.Our nanostructural design empowers mineral precursors with tailorable properties through encapsulating amorphous calcium phosphate within a multifunctional tannic acid(TA)and silk fibroin(SF)nanoshell.The bioinspired nanosystem facilitates efficient recruitment of mineral precursors throughout the dentin structures,followed by large-scale intradentinal mineralization both in vitro and in vivo,which provides persistent protection against external stimuli.Theoretical simulations combined with experimental studies attribute the success of intradentinal mineralization to the TA-SF nanoshell,which exhibits a strong affinity for the dentin structure,stabilizing amorphous precursors and thereby facilitating concomitant mineral formation.Overall,this bioinspired mineral-in-shell nanoarchitectonics shows a promising prospect for hard tissue repair and serves as a blueprint for next-generation biomineralization-associated materials.展开更多
Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental e...Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.展开更多
The invasion of etched dentinal tubules(DTs)by external substances induces dentin hypersensitivity(DH).The deep and compact occlusion of DTs is highly desirable for treating DH but still challenging due to the limited...The invasion of etched dentinal tubules(DTs)by external substances induces dentin hypersensitivity(DH).The deep and compact occlusion of DTs is highly desirable for treating DH but still challenging due to the limited penetrability and mineralization capacities of most current desensitizers.Matrix vesicles(MVs)participate in the regulation of ectopic mineralization.Herein,ectopic MV analogs are prepared by employing natural cell membranes to endow mineral precursors with natural biointerfaces and integrated biofunctions for stimulating dentin remineralization.The analogs quickly access DTs(>20μm)in only 5 min and further penetrate deep into the interior of DTs(an extraordinary~200μm)in 7 days.Both in vitro and in vivo studies confirm that the DTs are efficiently sealed by the newly formed minerals(>50μm)with excellent resistance to wear and acid erosion,which is significantly deeper than most reported values.After repair,the microhardness of the damaged dentin can be recovered to those of healthy dentin.For the first time,cell membrane coating nanotechnology is used as a facile and efficient therapy for in-depth remineralization of DTs in treating DH with thorough and long-term effects,which provides insights into their potential for hard tissue repair.展开更多
The sensing of hot and cold stimuli by dental neurons differs in several fundamental ways. These sensations have been characterized quantitatively through the measured time course of neural discharge signals that resu...The sensing of hot and cold stimuli by dental neurons differs in several fundamental ways. These sensations have been characterized quantitatively through the measured time course of neural discharge signals that result from hot or cold stimuli applied to the teeth of animal models. Although various hypotheses have been proposed to explain the underlying mechanism, the ability to test competing hypotheses against experimental recorded data using biophysical models has been hindered by limitations in our understanding of the specific ion channels involved in nociception of dental neurons. Here we apply recent advances in established biophysical models to test the competing hypotheses. We show that a sharp shooting pain sensation experienced shortly following cold stimulation cannot be attributed to the activation of thermosensitive ion channels, thereby falsifying the so-called neuronal hypothesis, which states that rapidly transduced sensations of coldness are related to thermosensitive ion channels. Our results support a central role of mechanosensitive ion channels and the associated hydrodynamic hypothesis. In addition to the hydrodynamic hypothesis, we also demonstrate that the long time delay of dental neuron responses after hot stimulation could be attributed to the neuronal hypothesis-that a relatively long time is required for the temperature around nociceptors to reach some threshold. The results are useful as a model of how multiphysical phenomena can be combined to provide mechanistic insight into different mechanisms underlying pain sensations.展开更多
Dentin hypersensitivity(DH)associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration.Medication,filling repair,laser irradiation,crown therapy,and des...Dentin hypersensitivity(DH)associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration.Medication,filling repair,laser irradiation,crown therapy,and desensitizing toothpaste are standard clinical treatment strategies,but unsatisfactory treatment modalities are marked by long-term administration,poor dentinal tubule closure,microleakage,and the development of secondary caries.To improve the treatment efficiency of DH,numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization.Biomaterials are expected to participate in dental remineralization to achieve desensitization.This review discusses various biomaterials for DH therapy based on different desensitization mechanisms,including dentinal tubule closure and dental nerve blockade,and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.展开更多
Stem cells are pluripotent cells, having a property of differentiating into various types of cells of human body. Several studies have developed mesenchymal stem cells(MSCs) from various human tissues,peripheral blood...Stem cells are pluripotent cells, having a property of differentiating into various types of cells of human body. Several studies have developed mesenchymal stem cells(MSCs) from various human tissues,peripheral blood and body fluids. These cells are then characterized by cellular and molecular markers to understand their specific phenotypes. Dental pulp stem cells(DPSCs) are having a MSCs phenotype and they are differentiated into neuron, cardiomyocytes, chondrocytes, osteoblasts, liver cells and β cells of islet of pancreas. Thus, DPSCs have shown great potentiality to use in regenerative medicine for treatment of various human diseases including dental related problems. These cells can also be developed into induced pluripotent stem cells by incorporation of pluripotency markers and use for regenerative therapies of various diseases. The DPSCs are derived from various dental tissues such as human exfoliated deciduous teeth, apical papilla, periodontal ligament and dental follicle tissue. This review will overview the information about isolation, cellular and molecular characterization and differentiation of DPSCs into various types of human cells and thus these cells have important applications in regenerative therapies for various diseases. This review will be most useful for postgraduate dental students as well as scientists working in the field of oral pathology and oral medicine.展开更多
The tooth root cementum is a thin, mineralized tissue covering the root dentin that is present primarily as acellular cementum on the cervical root and cellular cementum covering the apical root. While cementum shares...The tooth root cementum is a thin, mineralized tissue covering the root dentin that is present primarily as acellular cementum on the cervical root and cellular cementum covering the apical root. While cementum shares many properties in common with bone and dentin, it is a unique mineralized tissue and acellular cementum is critical for attachment of the tooth to the surrounding periodontal ligament （PDL）. Resources for methodologies for hard tissues often overlook cementum and approaches that may be of value for studying this tissue. To address this issue, this report offers detailed methodology, as well as comparisons of several histological and immunohistochemical stains available for imaging the cementum-PDL complex by light microscopy. Notably, the infrequently used Alcian blue stain with nuclear fast red counterstain provided utility in imaging cementum in mouse, porcine and human teeth. While no truly unique extracellular matrix markers have been identified to differentiate cementum from the other hard tissues, immunohistochemistry for detection of bone sialoprotein （BSP）, osteopontin （OPN）, and dentin matrix protein 1 （DMP1） is a reliable approach for studying both acellular and cellular cementum and providing insight into developmental biology of these tissues. Histoloeical and immunohistochemical aooroaches Drovide insight on developmental biology of cementum.展开更多
Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin（PA） for a clinically practical duration improves the mechanical properties of the dentin matrix and the immedia...Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin（PA） for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.展开更多
‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from out...‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from outside to inside. These attributes confer human teeth with effective mastication ability. Understanding the various mechanical properties of human teeth and dental materials is the basis for the development of restorative materials. In this study, the elastic properties, dynamic mechanical properties （visco-elasticity） and fracture mechanical properties of enamel and dentin were reviewed to provide a more thorough understanding of the mechanical properties of human teeth.展开更多
Phosphophoryn (PP) and dentin sialoprotein (DSP) are the most dominant non-collagenous proteins in dentin. PP is an extremely acidic protein that can function as a mineral nucleator for dentin mineralization. DSP was ...Phosphophoryn (PP) and dentin sialoprotein (DSP) are the most dominant non-collagenous proteins in dentin. PP is an extremely acidic protein that can function as a mineral nucleator for dentin mineralization. DSP was first identified in 1981, yet its functional significance is still controversial. Historically, these two proteins were considered to be independently synthesized and secreted by dental pulp cells into the developing dentin matrix. However, with the identification of the DSP coding sequence in 1994, followed2 years later by the finding that the PP coding sequence was located immediately downstream from the DSP sequence, it became immediately clear that DSP and PP proteins were derived from a single DSP-PP (i.e., dentin sialophosphoprotein, DSPP) transcript.Since DSPP cDNA became available, tremendous progress has been made in studying DSP-PP mRNA distribution and DSP generation from the DSP-PP precursor protein at specific cleavage sites by protease tolloid-related-1 (TLR1) or bone morphogenetic protein 1 (BMP1). The functions of DSP-PP and DSP were investigated via DSP-PP knockout (KO) and DSP knockin in DSP-PP KO mice. In addition, a number of in vitro studies aimed to elucidate DSPP and DSP function in dental pulp cells.展开更多
The aim of this study was to investigate the influence of ethylenediaminetetraacetic acid （EDTA） irrigation on demineralization rate of dentine located in the apical third of root canal walls. Teeth were divided int...The aim of this study was to investigate the influence of ethylenediaminetetraacetic acid （EDTA） irrigation on demineralization rate of dentine located in the apical third of root canal walls. Teeth were divided into A and B two groups. In group A, all of the teeth was irrigated with EDTA and NaOCI （sodium hypochlorite）, followed by cutting the apical third into slices longitudinally to examine the influence of EDTA on different portions of apical third of root canal. In group B, the apical third of a tooth was firstly cut into slices longitudinally, followed by coating the root canal walls with EDTA to in-situ observe the demineralization of dentine with different time. It was found that the influence of EDTA on root-canal was gradually increased from the apical to the upper end of the apical third for group A. In addition, the demineralization rate of dentine was remarkable in the first 25 min for group B. The diffusion of EDTA into root dentine would lead to potential damage to the dentine. Furthermore, demineralization rate curve was calculated.展开更多
Tooth decay is prevalent,and secondary caries causes restoration failures,both of which are related to demineralization.There is an urgent need to develop new therapeutic materials with remineralization functions.This...Tooth decay is prevalent,and secondary caries causes restoration failures,both of which are related to demineralization.There is an urgent need to develop new therapeutic materials with remineralization functions.This article represents the first review on the cutting edge research of poly(amido amine)(PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP).PAMAM was excellent nucleation template,and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization.NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities.PAMAM +NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates,superior acidneutralization,and ions release.Therefore,the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone.PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions.Besides,the long-term remineralization capability of PAMAM+NACP was established.After prolonged fluid challenge,the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration.Furthermore,the hardness of predemineralized dentin was increased back to that of healthy dentin,indicating a complete remineralization.Therefore,the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization,hardness increase,and caries-inhibition capabilities.展开更多
Antibacterial dimethylaminododecyl methacrylate （DMADDM） was recently synthesized. The objectives of this study were to： （1） investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans ...Antibacterial dimethylaminododecyl methacrylate （DMADDM） was recently synthesized. The objectives of this study were to： （1） investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and （2） compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate （QADM）. Scotchbond Multi-Purpose （SBMP） bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested： SBMP control primer P, P＋2.5% DMADDM, P＋5% DMADDM, P＋7.5% DMADDM, P＋10% DMADDM, and P＋10% QADM. S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units （CFU） and inhibition zones were measured. The bacterial inhibition zone of P＋10% DMADDM was 10 times that of control primer （P〈0.05）. CFU in dentin with P＋10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups （P〉0.1）. In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promisine for use in bonding agents as well as in other restorative and oreventive materials to inhibit bacteria.展开更多
To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it ...To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin.In this paper,by the digital speckle correlation method,tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules.With the theoretically predicted elastic stress-strain relations,an optimiza- tion method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations.The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5GPa and 0.44,respectively,in the optimization sense.展开更多
文摘This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were selected, including 18 males and 21 females. Forty-eight human maxillary first premolars from orthodontic extractions were chosen to prepare the test models with the dentinal tubule orientations perpendicular and parallel to the bonding substrate. The test models in the vertical and parallel groups were divided into three groups： total-etching with 20% phosphoric acid, total-etching with 35% phosphoric acid and self-etching, with the dentinal tubule surfaces bonded with composite resin blocks in each group. After the standard test models of dentinal tubule-composite resin blocks were placed in distilled water and stored at 37℃ for 24 h, shearing tests were performed using a universal material testing machine at a crosshead speed of 0.5 mm/min. The bond strength values in the vertical group were 19.33＋1.59 MPa for the 20% phosphoric acid group, 21.39±2.34 MPa for the 35% phosphoric acid group, and 16.88±1.54 MPa for the self-etching group. The bond strength values in the parallel group were 24.53±1.99 MPa for the 20% phosphoric acid group, 25.16＋2.88 MPa for the 35% phosphoric acid group, and 20.83±1.99 for the self-etching group. After using same total-etching adhesive, the shear bond strength of the parallel group was higher than that of the vertical group, and the difference was statistically significant （P〈0.05）. Regardless of vertical group or parallel group, the difference in the bond strength value between the total-etching groups and the self-etching group was statistically significant （P〈0.05）. It was concluded that the dentin bonding substrate which was parallel to the direction of the dentin tubule achieved an improved bond strength; the total-etching adhesives achieved higher bond strengths in dentin bond than the self-etching adhesives.
文摘Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm2, 200 J/cm2, 400 J/cm2 and 600 J/cm2, respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively;and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.
文摘The morpohologic feature of radicular dentin in sensitive and naturally desensitive area was observed with scanning electron microscopy (SEM). Eight specimens were taken from six patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hyperoensitive areas was much larger than that in naturally desensitive areas. The results suggest that theie is relationship between dentin moophology and dentin hypersensitivity. In this article, a new dentin bipopsy technique with hollow drill was reported also.
基金supported by the Japan Society for the Promotion of Science,Grants-in-Aid for Scientific Research Fundamental Research(C)19K10161.
文摘The aim of this study was to evaluate the dentinal tubule sealing and acid resistance of dentin specimens following the application of calcium phosphate glass powder prior to irradiation with a CO2(carbon dioxide)laser.Dentin models simulating open dentinal tubules were divided into two groups:experimental(calcium phosphate glass slurry applied to the dentin surface)and control(no slurry applied to the surface).All specimens in the experimental group and five specimens in the control group were irradiated with a CO2 laser.The defocused laser beams(0.5 and 1 W)were applied(spot size,5 mm in diameter)from a distance of 20 mm for 10 s.The surfaces and cross-sectional areas of the specimens were examined using an SEM(scanning electron microscope).In addition,the resistance to acid was evaluated in these specimens.The open dentinal tubules in the control groups were sealed following irradiation with the CO2 laser at 0.5 W and 1.0 W.Likewise,sealing of open dentinal tubules was observed in the experimental group after CO2 laser irradiation.The acid resistance of the dentin surface was improved after CO2 laser irradiation;specimens in the experimental group presented with significantly lower amounts of Ca ion release compared to those in the control group.These findings indicate that CO2 laser irradiation alone or after the application of calcium phosphate glass powder can effectively seal the dentinal tubules and alleviate dentin hypersensitivity.
文摘The morphologic feature of radicular dentin in sensitive and naturally desensitive areas was observed with scanning electron microscopy(SEM). Eight specimens were taken from six-patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hypersensitive areas was much larger than that in naturally desensitive areas. The results suggest that there is relationship between dentin morphology and dentin hypersensitivity. In this article, a new technique of dentin biopsy with hollow drill was reported also.
文摘The effects of occlusion of dentinal tubuls Im a Chinese traditional medicine Complex Gao Liang Jiang Paste were evaluated using scanning electron microscope and Oc-clusion of dentinal tubules occurred of after treatment with the preparation for 5 mm ohstructed after 10 min and complete occlusion after 20 min. In order to get ideal result the be lengthened when the paste is used.
基金support provided by the National Natural Science Foundation of China(Nos.52273135,51925304,52203180).
文摘Effective mineralization of biological structures poses a significant challenge in hard tissue engineering as it necessitates overcoming geometric complexities and multistep biomineralization processes.In this regard,we propose“mineral-in-shell nanoarchitectonics”,inspired by the nanostructure of matrix vesicles,which can influence multiple mineralization pathways.Our nanostructural design empowers mineral precursors with tailorable properties through encapsulating amorphous calcium phosphate within a multifunctional tannic acid(TA)and silk fibroin(SF)nanoshell.The bioinspired nanosystem facilitates efficient recruitment of mineral precursors throughout the dentin structures,followed by large-scale intradentinal mineralization both in vitro and in vivo,which provides persistent protection against external stimuli.Theoretical simulations combined with experimental studies attribute the success of intradentinal mineralization to the TA-SF nanoshell,which exhibits a strong affinity for the dentin structure,stabilizing amorphous precursors and thereby facilitating concomitant mineral formation.Overall,this bioinspired mineral-in-shell nanoarchitectonics shows a promising prospect for hard tissue repair and serves as a blueprint for next-generation biomineralization-associated materials.
基金We thank the National Key R&D Program of China(No.2020YFA0710401)the National Natural Science Foundation of China(Nos.82225012,81922019,82071161,81991505,22122207,21988102,and 52075138)+1 种基金the Young Elite Scientist Sponsorship Program by CAST(No.2020QNRC001)the Beijing Nova Program(No.211100002121013).
文摘Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.
基金the National Natural Science Foundation of China(Nos.51925304,51903175,and 51973133).
文摘The invasion of etched dentinal tubules(DTs)by external substances induces dentin hypersensitivity(DH).The deep and compact occlusion of DTs is highly desirable for treating DH but still challenging due to the limited penetrability and mineralization capacities of most current desensitizers.Matrix vesicles(MVs)participate in the regulation of ectopic mineralization.Herein,ectopic MV analogs are prepared by employing natural cell membranes to endow mineral precursors with natural biointerfaces and integrated biofunctions for stimulating dentin remineralization.The analogs quickly access DTs(>20μm)in only 5 min and further penetrate deep into the interior of DTs(an extraordinary~200μm)in 7 days.Both in vitro and in vivo studies confirm that the DTs are efficiently sealed by the newly formed minerals(>50μm)with excellent resistance to wear and acid erosion,which is significantly deeper than most reported values.After repair,the microhardness of the damaged dentin can be recovered to those of healthy dentin.For the first time,cell membrane coating nanotechnology is used as a facile and efficient therapy for in-depth remineralization of DTs in treating DH with thorough and long-term effects,which provides insights into their potential for hard tissue repair.
基金supported by the National Natural Science Foundation of China (Grants 11372243, 11522219, 11532009, and 11402192)the Fundamental Research Funds for the Central Universities (Grants 2016qngz03, 2015qngz09)the Openning Project of Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research,College of Stomatology, Xi’an Jiaotong University (Grant 2016LHM-KFKT007)
文摘The sensing of hot and cold stimuli by dental neurons differs in several fundamental ways. These sensations have been characterized quantitatively through the measured time course of neural discharge signals that result from hot or cold stimuli applied to the teeth of animal models. Although various hypotheses have been proposed to explain the underlying mechanism, the ability to test competing hypotheses against experimental recorded data using biophysical models has been hindered by limitations in our understanding of the specific ion channels involved in nociception of dental neurons. Here we apply recent advances in established biophysical models to test the competing hypotheses. We show that a sharp shooting pain sensation experienced shortly following cold stimulation cannot be attributed to the activation of thermosensitive ion channels, thereby falsifying the so-called neuronal hypothesis, which states that rapidly transduced sensations of coldness are related to thermosensitive ion channels. Our results support a central role of mechanosensitive ion channels and the associated hydrodynamic hypothesis. In addition to the hydrodynamic hypothesis, we also demonstrate that the long time delay of dental neuron responses after hot stimulation could be attributed to the neuronal hypothesis-that a relatively long time is required for the temperature around nociceptors to reach some threshold. The results are useful as a model of how multiphysical phenomena can be combined to provide mechanistic insight into different mechanisms underlying pain sensations.
基金This work was financially supported by the Special Program for Medical and Health Professionals of Jilin Province(No.JLSWSRCZX2021-085)the Achievement Transformation Fund of the First Hospital of Jilin University(Nos.JDYYZH-2102055 and JDYYZH-2102013).
文摘Dentin hypersensitivity(DH)associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration.Medication,filling repair,laser irradiation,crown therapy,and desensitizing toothpaste are standard clinical treatment strategies,but unsatisfactory treatment modalities are marked by long-term administration,poor dentinal tubule closure,microleakage,and the development of secondary caries.To improve the treatment efficiency of DH,numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization.Biomaterials are expected to participate in dental remineralization to achieve desensitization.This review discusses various biomaterials for DH therapy based on different desensitization mechanisms,including dentinal tubule closure and dental nerve blockade,and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.
基金Supported by Jaslok Hospital and Research Centre,Mumbai,India,Project ni491,A/C 27814
文摘Stem cells are pluripotent cells, having a property of differentiating into various types of cells of human body. Several studies have developed mesenchymal stem cells(MSCs) from various human tissues,peripheral blood and body fluids. These cells are then characterized by cellular and molecular markers to understand their specific phenotypes. Dental pulp stem cells(DPSCs) are having a MSCs phenotype and they are differentiated into neuron, cardiomyocytes, chondrocytes, osteoblasts, liver cells and β cells of islet of pancreas. Thus, DPSCs have shown great potentiality to use in regenerative medicine for treatment of various human diseases including dental related problems. These cells can also be developed into induced pluripotent stem cells by incorporation of pluripotency markers and use for regenerative therapies of various diseases. The DPSCs are derived from various dental tissues such as human exfoliated deciduous teeth, apical papilla, periodontal ligament and dental follicle tissue. This review will overview the information about isolation, cellular and molecular characterization and differentiation of DPSCs into various types of human cells and thus these cells have important applications in regenerative therapies for various diseases. This review will be most useful for postgraduate dental students as well as scientists working in the field of oral pathology and oral medicine.
基金supported (in part) by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health
文摘The tooth root cementum is a thin, mineralized tissue covering the root dentin that is present primarily as acellular cementum on the cervical root and cellular cementum covering the apical root. While cementum shares many properties in common with bone and dentin, it is a unique mineralized tissue and acellular cementum is critical for attachment of the tooth to the surrounding periodontal ligament （PDL）. Resources for methodologies for hard tissues often overlook cementum and approaches that may be of value for studying this tissue. To address this issue, this report offers detailed methodology, as well as comparisons of several histological and immunohistochemical stains available for imaging the cementum-PDL complex by light microscopy. Notably, the infrequently used Alcian blue stain with nuclear fast red counterstain provided utility in imaging cementum in mouse, porcine and human teeth. While no truly unique extracellular matrix markers have been identified to differentiate cementum from the other hard tissues, immunohistochemistry for detection of bone sialoprotein （BSP）, osteopontin （OPN）, and dentin matrix protein 1 （DMP1） is a reliable approach for studying both acellular and cellular cementum and providing insight into developmental biology of these tissues. Histoloeical and immunohistochemical aooroaches Drovide insight on developmental biology of cementum.
基金supported by research funds from the Natural Science Foundation of China (No. 81130078 and No. 81000458)Program for Changjiang Scholars and Innovative Research Team in University (No. IRT13051)
文摘Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin（PA） for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.
基金support from the National Natural Science Foundation of China(Nos.81170996,81070867 and 81100777)the Sichuan Province Science and Technology Innovation Team Program(2011JTD0006)
文摘‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from outside to inside. These attributes confer human teeth with effective mastication ability. Understanding the various mechanical properties of human teeth and dental materials is the basis for the development of restorative materials. In this study, the elastic properties, dynamic mechanical properties （visco-elasticity） and fracture mechanical properties of enamel and dentin were reviewed to provide a more thorough understanding of the mechanical properties of human teeth.
文摘Phosphophoryn (PP) and dentin sialoprotein (DSP) are the most dominant non-collagenous proteins in dentin. PP is an extremely acidic protein that can function as a mineral nucleator for dentin mineralization. DSP was first identified in 1981, yet its functional significance is still controversial. Historically, these two proteins were considered to be independently synthesized and secreted by dental pulp cells into the developing dentin matrix. However, with the identification of the DSP coding sequence in 1994, followed2 years later by the finding that the PP coding sequence was located immediately downstream from the DSP sequence, it became immediately clear that DSP and PP proteins were derived from a single DSP-PP (i.e., dentin sialophosphoprotein, DSPP) transcript.Since DSPP cDNA became available, tremendous progress has been made in studying DSP-PP mRNA distribution and DSP generation from the DSP-PP precursor protein at specific cleavage sites by protease tolloid-related-1 (TLR1) or bone morphogenetic protein 1 (BMP1). The functions of DSP-PP and DSP were investigated via DSP-PP knockout (KO) and DSP knockin in DSP-PP KO mice. In addition, a number of in vitro studies aimed to elucidate DSPP and DSP function in dental pulp cells.
基金the financial support of the project from the Foundation of the Education Department of Liaoning Province(Grant No.L2013285)Science and Technology Planning Project of Shenyang City(Grant No.F11262-9-16)
文摘The aim of this study was to investigate the influence of ethylenediaminetetraacetic acid （EDTA） irrigation on demineralization rate of dentine located in the apical third of root canal walls. Teeth were divided into A and B two groups. In group A, all of the teeth was irrigated with EDTA and NaOCI （sodium hypochlorite）, followed by cutting the apical third into slices longitudinally to examine the influence of EDTA on different portions of apical third of root canal. In group B, the apical third of a tooth was firstly cut into slices longitudinally, followed by coating the root canal walls with EDTA to in-situ observe the demineralization of dentine with different time. It was found that the influence of EDTA on root-canal was gradually increased from the apical to the upper end of the apical third for group A. In addition, the demineralization rate of dentine was remarkable in the first 25 min for group B. The diffusion of EDTA into root dentine would lead to potential damage to the dentine. Furthermore, demineralization rate curve was calculated.
基金supported by National Natural Science Foundation of China (81670977, J.L. and 81800965, K.L.)Sichuan Science and Technology program (Grant no. 2017SZ0030)+5 种基金Fundamental Research Funds for Central University 2018SCU12016 (K.L.)China Postdoctoral Science Grant 2018M643507 (K.L.)Research Fund of West China Hospital WCHS-201705 (K.L.)Research Fund for Resins of Chinese Stomatological Association CSA-R2018-06 (K.L.)University of Maryland School of Dentistry bridging fund (H.H.K.X.)University of Maryland Baltimore seed grant (H.H.K.X.)
文摘Tooth decay is prevalent,and secondary caries causes restoration failures,both of which are related to demineralization.There is an urgent need to develop new therapeutic materials with remineralization functions.This article represents the first review on the cutting edge research of poly(amido amine)(PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP).PAMAM was excellent nucleation template,and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization.NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities.PAMAM +NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates,superior acidneutralization,and ions release.Therefore,the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone.PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions.Besides,the long-term remineralization capability of PAMAM+NACP was established.After prolonged fluid challenge,the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration.Furthermore,the hardness of predemineralized dentin was increased back to that of healthy dentin,indicating a complete remineralization.Therefore,the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization,hardness increase,and caries-inhibition capabilities.
基金supported by NIH R01 DE17974 (Hockin HK Xu)a scholarship from West China School of Stomatology (Chen Chen)+3 种基金Program for New Century Excellent Talents in University (Lei Cheng)Youth Grant of Science and Technology Department of Sichuan Province China (2014JQ0033) (Lei Cheng)a bridge fund from University of Maryland Baltimore School of Dentistry (Hockin HK Xu)a seed grant from University of Maryland Baltimore (Hockin HK Xu)
文摘Antibacterial dimethylaminododecyl methacrylate （DMADDM） was recently synthesized. The objectives of this study were to： （1） investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and （2） compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate （QADM）. Scotchbond Multi-Purpose （SBMP） bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested： SBMP control primer P, P＋2.5% DMADDM, P＋5% DMADDM, P＋7.5% DMADDM, P＋10% DMADDM, and P＋10% QADM. S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units （CFU） and inhibition zones were measured. The bacterial inhibition zone of P＋10% DMADDM was 10 times that of control primer （P〈0.05）. CFU in dentin with P＋10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups （P〉0.1）. In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promisine for use in bonding agents as well as in other restorative and oreventive materials to inhibit bacteria.
基金The project supported by the National Natural Science Foundation of China(19525207)
文摘To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin.In this paper,by the digital speckle correlation method,tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules.With the theoretically predicted elastic stress-strain relations,an optimiza- tion method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations.The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5GPa and 0.44,respectively,in the optimization sense.
