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Scientific Reports Sep 2023Dentin hypersensitivity is an oral health concern affecting a large percentage of the world's adult population. Occlusion of the exposed dentinal tubules is among the...
Dentin hypersensitivity is an oral health concern affecting a large percentage of the world's adult population. Occlusion of the exposed dentinal tubules is among the treatment options available, and silver diammine fluoride (SDF) is an occluding agent used for interrupting or dampening the stimulus of the dental pulp nerves that produce pain. In addition to dentin permeability testing, the evaluation of desensitizing agents occluding dentinal tubules strongly relies on microscopic techniques, such as scanning electron microscopy (SEM). Limitations of SEM are that it provides only surface images that lack detailed information on the depth of penetration and amount of material present within the treated specimen, and it is prone to sample preparation artifacts. Here, we present high-resolution X-ray computed tomography (nano-CT) as a potential method for investigating dentin specimens with occluded tubules. We studied human dentin treated with SDF as an exemplary dentinal occlusion treatment option. We evaluated the silver deposits formed on the dentin surface region near the dentinal tubules and in the tubular regions using cross-section SEM, Energy Dispersive X-ray (EDX) analysis, and nano-CT. The resulting images obtained by SEM and nano-CT had comparable resolutions, and both techniques produced images of the tubules' occlusion. Nano-CT provided three-dimensional images adequate to quantitate tubule size and orientation in space. Moreover, it enabled clear visualization of dentinal tubules in any virtual plane and estimation of the amount and depth of occluding material. Thus, nano-CT has the potential to be a valuable technique for evaluating the occluding effects of virtually any material applied to dentinal tubules, supporting deciding between the best occluding treatment options.
Topics: Adult; Humans; Tomography, X-Ray Computed; Artifacts; Microscopy, Electron, Scanning; Dentin
PubMed: 37741849
DOI: 10.1038/s41598-023-42805-8 -
Journal of Biomedical Optics 2007In this study, we used an epi-illuminated multiphoton microscope to image three main components of ex vivo human tooth. In particular, we obtained two-photon excited...
In this study, we used an epi-illuminated multiphoton microscope to image three main components of ex vivo human tooth. In particular, we obtained two-photon excited autofluorescence (AF) and second-harmonic generation (SHG) images of the enamel, dentin, and periodontal ligaments (PLs) and constructed three-dimensional projections of sequentially and axially acquired images. We found that the enamel has a strong two-photon AF signal, clearly revealing the structures of the enamel rods. The dentin, on the other hand, has both AF and SHG signals. The contrast provided by the combination of these two imaging modalities can be used to reveal the structure of peritubular dentin and to distinguish the less mineralized circumpulpal dentins. The SHG and multiphoton AF imaging also showed the structure of the PL and the distribution of cells around the PL, respectively. For comparison, we also obtained scanning electron microscopy images of the enamel, dentin, circumpulpal dentin, and the PL. Our results demonstrate the effectiveness of using multiphoton microscopy to visualize the major constituents of teeth, including enamel, dentin, and the PL, and the potential of this minimally invasive technique for monitoring the morphological developments during tooth regeneration.
Topics: Adult; Dental Enamel; Dentin; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Microscopy, Electron, Scanning; Microscopy, Fluorescence, Multiphoton; Periodontal Ligament; Tooth
PubMed: 18163834
DOI: 10.1117/1.2812710 -
International Journal of Nanomedicine 2019Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the...
INTRODUCTION
Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the formation of collagen fibrils in dentin, leading to morphological and structural changes that affect the strength and appearance of teeth. However, there is still a lack of understanding regarding the nanoscale characterization of the disease, in terms of collagen ultrastructure and mechanical properties. Therefore, this research presents a qualitative and quantitative report into the phenotype and characterization of OIDI in dentin, by using a combination of imaging, nanomechanical approaches.
METHODS
For this study, 8 primary molars from OIDI patients and 8 primary control molars were collected, embedded in acrylic resin and cut into longitudinal sections. Sections were then demineralized in 37% phosphoric acid using a protocol developed in-house. Initial experiments demonstrated the effectiveness of the demineralization protocol, as the ATR-FTIR spectral fingerprints showed an increase in the amide bands together with a decrease in phosphate content. Structural and mechanical analyses were performed directly on both the mineralized and demineralized samples using a combination of scanning electron microscopy, atomic force microscopy, and Wallace indentation.
RESULTS
Mesoscale imaging showed alterations in dentinal tubule morphology in OIDI patients, with a reduced number of tubules and a decreased tubule diameter compared to healthy controls. Nanoscale collagen ultrastructure presented a similar D-banding periodicity between OIDI and controls. Reduced collagen fibrils diameter was also recorded for the OIDI group. The hardness of the (mineralized) control dentin was found to be significantly higher (p<0.05) than that of the OIDI (mineralized) dentine. Both the exposed peri- and intratubular dentinal collagen presented bimodal elastic behaviors (Young's moduli). The control samples presented a stiffening of the intratubular collagen when compared to the peritubular collagen. In case of the OIDI, this stiffening in the collagen between peri- and intratubular dentinal collagen was not observed and the exposed collagen presented overall a lower elasticity than the control samples.
CONCLUSION
This study presents a systematic approach to the characterization of collagen structure and properties in OIDI as diagnosed in dentin. Structural markers for OIDI at the mesoscale and nanoscale were found and correlated with an observed lack of increased elastic moduli of the collagen fibrils in the intratubular OIDI dentin. These findings offer an explanation of how structural changes in the dentin could be responsible for the failure of some adhesive restorative materials as observed in patients affected by OIDI.
Topics: Collagen; Dentin; Dentinogenesis Imperfecta; Elasticity; Hardness; Humans; Molar; Osteogenesis Imperfecta; Phenotype; Radiography, Bitewing; Spectroscopy, Fourier Transform Infrared; Tooth Demineralization
PubMed: 31819441
DOI: 10.2147/IJN.S217420 -
Zhong Nan Da Xue Xue Bao. Yi Xue Ban =... Jun 2018To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed...
To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface. Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface. Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open. Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.
Topics: Dental Pulp Cavity; Dentin; Glass; Microscopy, Electron, Scanning; Saliva, Artificial; Spectroscopy, Fourier Transform Infrared; Tooth Remineralization
PubMed: 30110003
DOI: 10.11817/j.issn.1672-7347.2018.06.007 -
Archives of Oral Biology Sep 2021Our goal was to define trigeminal nerve ending quantities and patterns in rat molar dentine, their responses to attrition (tooth wear), and their associated odontoblasts...
OBJECTIVE
Our goal was to define trigeminal nerve ending quantities and patterns in rat molar dentine, their responses to attrition (tooth wear), and their associated odontoblasts and connections with pulpal plexuses.
DESIGN
Trigeminal ganglia were labeled for axonal transport of H-proteins to dentinal nerve endings in male rats (3-13 months old). Autoradiography detected radio-labeled dentinal tubules as indicators of nerve ending locations. Quantitative morphometry was done (ANOVA, t-tests), and littermates were compared for attrition and innervation.
RESULTS
There were six dentinal patterns, only two of which had an associated neural plexus of Raschkow and cell-free zone (Den-1, Den-2). Other nerves entered dentin from bush-like endings near elongated odontoblasts (Den-B), as single fibers (Den-X), as networks in predentine (PdN), or as single fibers in tertiary dentine at cusp tips (Den-S). There were at least 186,600 innervated dentinal tubules within the set of three right maxillary molars of the best-labeled rat, and similar densities were found in other rats. Attrition levels differed among cusps and in littermates (t-test p < 0.02-0.0001), but the matched right/left cusps per rat were similar. Innervations of tertiary and enamel-free dentine (Den-S, Den-X) were preserved in all rats. Den-B and Den-2 coronal patterns were unchanged unless displaced by dentinogenesis. Den-1 losses occurred in older cusps, while Den-2 patterns increased near cervical and intercuspal odontoblasts.
CONCLUSIONS
The extensive molar dentinal innervation had unique distributions per rat per cusp that depended on region (buccal, middle, palatal) and attrition, but only two of six patterns connected to a plexus of Raschkow.
Topics: Animals; Dental Pulp; Dentin; Male; Molar; Odontoblasts; Rats; Trigeminal Nerve
PubMed: 34146928
DOI: 10.1016/j.archoralbio.2021.105197 -
American Journal of Physical... Aug 2019This study explores the outer and inner crown of lower third and fourth premolars (P , P ) by analyzing the morphological variation among diverse modern human groups.
OBJECTIVES
This study explores the outer and inner crown of lower third and fourth premolars (P , P ) by analyzing the morphological variation among diverse modern human groups.
MATERIALS AND METHODS
We studied three-dimensional models of the outer enamel surface and the enamel-dentine junction (EDJ) from μCT datasets of 77 recent humans using both an assessment of seven nonmetric traits and a standard geometric morphometric (GM) analysis. For the latter, the dental crown was represented by four landmarks (dentine horns and fossae), 20 semilandmarks along the EDJ marginal ridge, and pseudolandmarks along the crown and cervical outlines.
RESULTS
Certain discrete traits showed significantly different regional frequencies and sexual dimorphism. The GM analyses of both P s and P s showed extensive overlap in shape variation of the various populations (classification accuracy 15-69%). The first principal components explained about 40% of shape variance with a correlation between 0.59 and 0.87 of the features of P s and P s. Shape covariation between P s and P s expressed concordance of high and narrow or low and broad crowns.
CONCLUSIONS
Due to marked intragroup and intergroup variation in GM analyses of lower premolars, discrete traits such as the number of lingual cusps and mesiolingual groove expression provide better geographic separation of modern human populations. The greater variability of the lingual region suggests a dominance of functional constraints over geographic provenience or sex. Additional information about functionally relevant aspects of the crown surface and odontogenetic data are needed to unravel the factors underlying dental morphology in modern humans.
Topics: Adolescent; Adult; Anthropology, Physical; Bicuspid; Child; Child, Preschool; Dental Enamel; Dentin; Female; Humans; Imaging, Three-Dimensional; Male; Middle Aged; Multivariate Analysis; Odontometry; Tooth Crown; X-Ray Microtomography; Young Adult
PubMed: 31099892
DOI: 10.1002/ajpa.23858 -
Frontiers in Bioscience (Scholar... Feb 2023Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for...
BACKGROUND
Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for resistance of this teeth may decrease the treatment's failure rate. So, this study was conducted to evaluate the dentin thickness of the danger zone in mesial roots of mandibular first molars using cone beam computed tomography in an Iranian population.
METHODS
In this cross-sectional study, 210 Cone Beam Computed Tomography acquisition of the mandibular first molars were collected from a radiology center in Qazvin. The dentin thickness of the mesial roots (mesiobuccal and mesiolingual canals) was measured from the furcation to 5 mm below. The relationship between the dentin thickness in the danger zone and parameters, like age, gender, placement side, root length, the curvature of the canal, canal type, presence of middle mesial canal, and distance between the orifices of the mesial canals was investigated. Frequency, mean and standard deviation for variables were calculated, and data analysis was done by SPSS using simple and multiple linear regression and Pearson correlation coefficient. Also, two-sample -test was used to compare mesiobuccal and mesiolingual on two sides. The significant level was also considered at ( < 0.05).
RESULTS
The average minimum thickness of danger zone dentin was found to be 0.885 ± 0.259 mm in the mesiobuccal canal and 0.906 ± 0.206 mm in the mesiolingualcanal. Also, the minimum thickness of dentin in the mesiobuccal and mesiolingual canals in the range of 0 to 1 mm from the furcation was more than in other areas. There was no significant relationship between the minimum dentin thickness of the danger zone with gender, placement side, root length, canal type, and mesial canal entrance distance. But with increasing age, the thickness of dentin in the danger zone in the mesiolingualcanal increased significantly ( = 0.008). It was also observed that with the increase in the curvature of the canal, the thickness of the dentin in the danger zone in the mesiobuccal canal decreased (moderately curved ( = 0.008), severely curved ( = 0.046)). In addition, the thickness of the dentin in the mesiobuccal and mesiolingual canal was less in the samples with the middle mesial canal ( = 0.047, 0.044).
CONCLUSIONS
Less dentin thickness in the danger zone in the mesial roots of mesiolingual mandibular first molars was seen in younger patients in mesiolingual canal, with a greater degree of canal curvature in the mesiobuccal canal and teeth with a middle mesial canal. Therefore, it is suggested that large taper instruments should be used with more precision to prevent complications.
Topics: Humans; Cross-Sectional Studies; Iran; Dentin; Mandible; Cone-Beam Computed Tomography
PubMed: 36959111
DOI: 10.31083/j.fbs1501003 -
Journal of Oral Science Mar 2010This study was done to assess the influence of the topical application of two different desensitizing agents on dentin permeability and dentinal tubule occlusion....
This study was done to assess the influence of the topical application of two different desensitizing agents on dentin permeability and dentinal tubule occlusion. Twenty-one rats provided 84 teeth: 36 for the in vitro and 48 for the in vivo investigation. The following agents were tested: Group 1, 2% potassium nitrate plus 2% sodium fluoride gel; Group 2, 5% sodium fluoride varnish; Group 3, 3% hydroxyethylcellulose gel (control). Cervical cavities were prepared and EDTA was applied to expose the dentinal tubules. After each treatment, Evans blue dye was applied to the teeth. Dentin permeability, scanning electron microscope (SEM) sections, and energy dispersive X-ray (EDX) were analyzed. One-way ANOVA was used to compare the data. There were significant differences (P < 0.05) among groups for dentin permeability, number of tubules/mm(2), tubule area and tubular diameter. Groups 1 and 2 (both in vitro and in vivo) showed open and partially occluded tubules. Group 3 had the most open tubules. EDX revealed similar composition for both experimental conditions. Within the limits of the study, 2% nitrate potassium plus 2% sodium fluoride gel and 5% fluoride varnish decreased the dentin permeability, resulting in partial tubular occlusion.
Topics: Animals; Dentin; Dentin Desensitizing Agents; Dentin Permeability; Drug Combinations; Fluorides, Topical; Male; Microscopy, Electron, Scanning; Nitrates; Potassium Compounds; Random Allocation; Rats; Rats, Wistar; Reproducibility of Results; Sodium Fluoride; Spectrometry, X-Ray Emission
PubMed: 20339229
DOI: 10.2334/josnusd.52.23 -
Acta Biomaterialia Mar 2016Human dental tissue is a hydrated biological mineral composite. In terms of volume and mass, a human tooth mainly consists of dentine and enamel. Human dental tissues...
UNLABELLED
Human dental tissue is a hydrated biological mineral composite. In terms of volume and mass, a human tooth mainly consists of dentine and enamel. Human dental tissues have a hierarchical structure and versatile mechanical properties. The dentine enamel junction (DEJ) is an important biological interface that provides a durable bond between enamel and dentine that is a life-long success story: while intact and free from disease, this interface does not fail despite the harsh thermo-mechanical loading in the oral cavity. The underlying reasons for such remarkable strength and durability are still not fully clear from the structural and mechanical perspectives. One possibility is that, in an example of residual stress engineering, evolution has led to the formation of a layer of inelastic strain adjacent to the DEJ during odontogenesis (tooth formation). However, due to significant experimental and interpretational challenges, no meaningful quantification of residual stress in the vicinity of the DEJ at the appropriate spatial resolution has been reported to date. In this study, we applied a recently developed flexible and versatile method for measuring the residual elastic strain at (sub)micron-scale utilising focused ion beam (FIB) milling with digital image correlation (DIC). We report the results that span the transition from human dentine to enamel, and incorporate the material lying at and in the vicinity of the DEJ. The capability of observing the association between internal architecture and the residual elastic strain state at the micrometre scale is useful for understanding the remarkable performance of the DEJ and may help the creation of improved biomimetic materials for clinical and engineering applications.
STATEMENT OF SIGNIFICANCE
We studied the micron-scale residual stresses that exist within human teeth, between enamel (outer tooth shell, hardest substance in the human body) and dentine (soft bone-like vascularised tooth core). The dentine-enamel junction (DEJ) is an extremely interesting example of nature's design in terms of hierarchical structuring and residual stress management. Key developments reported are systematic focused ion beam (FIB) milling and digital image correlation (DIC) micrometre scale residual strain evaluation, and the determination of principal strain direction near DEJ, correlated with internal architecture responsible for remarkable strength. This work helps understanding DEJ performance and improving biomimetic materials design for clinical and engineering applications.
Topics: Dental Enamel; Dentin; Elasticity; Humans; Image Processing, Computer-Assisted; Ions; Stress, Mechanical
PubMed: 26779888
DOI: 10.1016/j.actbio.2016.01.009 -
International Journal of Oral Science Dec 2009Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze... (Review)
Review
Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.
Topics: Chlorhexidine; Collagen; Dental Bonding; Dentin; Dentin-Bonding Agents; Enzyme Inhibitors; Humans; Hydrolysis; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Resin Cements
PubMed: 20690420
DOI: 10.4248/IJOS.09044