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International Journal of Molecular... Feb 2020Sonic hedgehog (Shh) is a secreted protein with important roles in mammalian embryogenesis. During tooth development, Shh is primarily expressed in the dental... (Review)
Review
Sonic hedgehog (Shh) is a secreted protein with important roles in mammalian embryogenesis. During tooth development, Shh is primarily expressed in the dental epithelium, from initiation to the root formation stages. A number of studies have analyzed the function of Shh signaling at different stages of tooth development and have revealed that Shh signaling regulates the formation of various tooth components, including enamel, dentin, cementum, and other soft tissues. In addition, dental mesenchymal cells positive for Gli1, a downstream transcription factor of Shh signaling, have been found to have stem cell properties, including multipotency and the ability to self-renew. Indeed, Gli1-positive cells in mature teeth appear to contribute to the regeneration of dental pulp and periodontal tissues. In this review, we provide an overview of recent advances related to the role of Shh signaling in tooth development, as well as the contribution of this pathway to tooth homeostasis and regeneration.
Topics: Animals; Dental Enamel; Dental Pulp; Epithelium; Hedgehog Proteins; Homeostasis; Humans; Mesenchymal Stem Cells; Odontogenesis; Signal Transduction; Tooth; Tooth Root; Zinc Finger Protein GLI1
PubMed: 32111038
DOI: 10.3390/ijms21051587 -
Development (Cambridge, England) Feb 2017The tooth root is an integral, functionally important part of our dentition. The formation of a functional root depends on epithelial-mesenchymal interactions and... (Review)
Review
The tooth root is an integral, functionally important part of our dentition. The formation of a functional root depends on epithelial-mesenchymal interactions and integration of the root with the jaw bone, blood supply and nerve innervations. The root development process therefore offers an attractive model for investigating organogenesis. Understanding how roots develop and how they can be bioengineered is also of great interest in the field of regenerative medicine. Here, we discuss recent advances in understanding the cellular and molecular mechanisms underlying tooth root formation. We review the function of cellular structure and components such as Hertwig's epithelial root sheath, cranial neural crest cells and stem cells residing in developing and adult teeth. We also highlight how complex signaling networks together with multiple transcription factors mediate tissue-tissue interactions that guide root development. Finally, we discuss the possible role of stem cells in establishing the crown-to-root transition, and provide an overview of root malformations and diseases in humans.
Topics: Animals; Bone Morphogenetic Proteins; Fibroblast Growth Factors; Hedgehog Proteins; Humans; Mice; Mice, Mutant Strains; Models, Dental; Odontogenesis; Signal Transduction; Stem Cells; Tooth Abnormalities; Tooth Crown; Tooth Root; Transforming Growth Factor beta; Wnt Signaling Pathway
PubMed: 28143844
DOI: 10.1242/dev.137216 -
Journal of Endodontics Jan 2004Locating the number and position of orifices on pulp-chamber floors can be difficult. This is especially true when the tooth being treated is heavily restored, malposed,...
Locating the number and position of orifices on pulp-chamber floors can be difficult. This is especially true when the tooth being treated is heavily restored, malposed, or calcified. After evaluating 500 pulp chambers of extracted teeth, new laws for finding pulp chambers and root-canal orifices are proposed. The use of these laws can aid in the determination of the pulp-chamber position and the exact location and number of root canals in any individual tooth.
Topics: Color; Dental Pulp Cavity; Dentin; Humans; Odontometry; Tooth Apex; Tooth Cervix; Tooth Root
PubMed: 14760900
DOI: 10.1097/00004770-200401000-00002 -
Journal of Dental Research Sep 2021Biomineralization of enamel, dentin, and bone involves the deposition of apatite mineral crystals within an organic matrix. Bone and teeth are classic examples of... (Review)
Review
Biomineralization of enamel, dentin, and bone involves the deposition of apatite mineral crystals within an organic matrix. Bone and teeth are classic examples of biomaterials with unique biomechanical properties that are crucial to their function. The collagen-based apatite mineralization and the important function of noncollagenous proteins are similar in dentin and bone; however, enamel is formed in a unique amelogenin-containing protein matrix. While the structure and organic composition of enamel are different from those of dentin and bone, the principal molecular mechanisms of protein-protein interactions, protein self-assembly, and control of crystallization events by the organic matrix are common among these apatite-containing tissues. This review briefly summarizes enamel and dentin matrix components and their interactions with other extracellular matrix components and calcium ions in mediating the mineralization process. We highlight the crystallization events that are controlled by the protein matrix and their interactions in the extracellular matrix during enamel and dentin biomineralization. Strategies for peptide-inspired biomimetic growth of tooth enamel and bioinspired mineralization of collagen to stimulate repair of demineralized dentin and bone tissue engineering are also addressed.
Topics: Amelogenin; Biomineralization; Collagen; Dental Enamel; Dentin
PubMed: 34151644
DOI: 10.1177/00220345211018405 -
Australian Dental Journal Jun 2011Improved dental adhesive technology has extensively influenced modern concepts in restorative dentistry. In light of minimal-invasive dentistry, this new approach... (Review)
Review
Improved dental adhesive technology has extensively influenced modern concepts in restorative dentistry. In light of minimal-invasive dentistry, this new approach promotes a more conservative cavity design, which basically relies on the effectiveness of current enamel-dentine adhesives. Nowadays, the interaction of adhesives with the dental substrate is based on two different strategies, commonly described as an etch-and-rinse and a self-etch approach. In an attempt to simplify the bonding technique, manufacturers have decreased the number of steps necessary for the accomplishment of the bonding procedure. As a consequence, two-step etch-and-rinse and one-step (self-etch) adhesives were introduced and gained rapid popularity in the dental market due to their claimed user-friendliness and lower technique sensitivity. However, many concerns have been raised on the bonding effectiveness of these simplified adhesives, especially in terms of durability, although this tends to be very material dependent. In order to blend all the adhesive components into one single solution, one-step adhesives were made more acidic and hydrophilic. Unfortunately, these properties induce a wide variety of seemingly unrelated problems that may jeopardize the effectiveness and stability of adhesion to the dental substrate. Being more susceptible to water sorption and thus nanoleakage, these adhesives are more prone to bond degradation and tend to fail prematurely as compared to their multi-step counterparts. Incidentally, another factor that may interfere with the bonding effectiveness of adhesives is the technique used for caries removal and cavity preparation. Several tools are on the market today to effectively remove carious tissue, thereby respecting the current trend of minimum intervention. Despite their promising performance, such techniques modify the tooth substrate in different aspects, possibly affecting bonding effectiveness. Altogether, we may conclude that not only the adhesive formulation, but also substrate nature must be taken into account to achieve a stable bonding interface, rendering the restorative treatment more predictable in terms of clinical performance. In this review, we analyse the current theoretical and clinical aspects of adhesion to enamel and dentine, and discuss the diverse possibilities to overcome problems which nowadays still challenge clinicians in their achievement of a more stable and effective bond to tooth enamel and dentine.
Topics: Adhesiveness; Adhesives; Dental Bonding; Dental Cavity Preparation; Dental Enamel; Dental Etching; Dental Stress Analysis; Dentin; Dentin-Bonding Agents; Humans
PubMed: 21564114
DOI: 10.1111/j.1834-7819.2011.01294.x -
Progress in Neurobiology Feb 1995(1) Although our knowledge on teeth and tooth nerves has increased substantially during the past 25 years, several important issues remain to be fully elucidated. As a... (Review)
Review
(1) Although our knowledge on teeth and tooth nerves has increased substantially during the past 25 years, several important issues remain to be fully elucidated. As a result of the work now going on at many laboratories over the world, we can expect exciting new findings and major break-throughs in these and other areas in a near future. (2) Dentin-like and enamel-like hard tissues evolved as components of the exoskeletal bony armor of early vertebrates, 500 million years ago, long before the first appearance of teeth. It is possible that teeth developed from tubercles (odontodes) in the bony armor. The presence of a canal system in the bony plates, of tubular dentin, of external pores in the enamel layer and of a link to the lateral line system promoted hypotheses that the bony plates and tooth precursors may have had a sensory function. The evolution of an efficient brain, of a head with paired sense organs and of toothed jaws concurred with a shift from a sessile filter-feeding life to active prey hunting. (3) The wide spectrum of feeding behaviors exhibited by modern vertebrates is reflected by a variety of dentition types. While the teeth are continuously renewed in toothed non-mammalian vertebrates, tooth turnover is highly restricted in mammals. As a rule, one set of primary teeth is replaced by one set of permanent teeth. Since teeth are richly innervated, the turnover necessitates a local neural plasticity. Another factor calling for a local plasticity is the relatively frequent occurrence of age-related and pathological dental changes. (4) Tooth development is initiated through interactions between the oral epithelium and underlying neural crest-derived mesenchymal cells. The interactions are mediated by cell surface molecules, extracellular matrix molecules and soluble molecules. The possibility that the initiating events might involve a neural component has been much discussed. With respect to mammals, the experimental evidence available does not support this hypothesis. In the teleost Tilapia mariae, on the other hand, tooth germ formation is interrupted, and tooth turnover ceases after local denervation. (5) Prospective dental nerves enter the jaws well before onset of tooth development. When a dental lamina has formed, a plexus of nerve branches is seen in the subepithelial mesenchyme. Shortly thereafter, specific branches to individual tooth primordia can be distinguished. In bud stage tooth germs, axon terminals surround the condensed mesenchyme and in cap stage primordia axons grow into the dental follicle.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Dental Pulp; Gingiva; Humans; Tooth
PubMed: 7777672
DOI: 10.1016/0301-0082(94)00045-j -
Cell and Tissue Research Dec 2016Vangl2, one of the core components of the planar cell polarity (PCP) pathway, has an important role in the regulation of morphogenesis in several tissues. Although the...
Vangl2, one of the core components of the planar cell polarity (PCP) pathway, has an important role in the regulation of morphogenesis in several tissues. Although the expression of Vangl2 has been detected in the developing tooth, its role in tooth morphogenesis is not known. In this study, we show that Vangl2 is expressed in the inner dental epithelium (IDE) and in the secondary enamel knots (SEKs) of bell stage tooth germs. Inhibition of Vangl2 expression by siRNA treatment in in vitro-cultured tooth germs resulted in retarded tooth germ growth with deregulated cell proliferation and apoptosis. After kidney transplantation of Vangl2 siRNA-treated tooth germs, teeth were observed to be small and malformed. We also show that Vangl2 is required to maintain the proper pattern of cell alignment in SEKs, which maybe important for the function of SEKs as signaling centers. These results suggest that Vangl2 plays an important role in the morphogenesis of teeth.
Topics: Animals; Apoptosis; Cell Polarity; Cell Proliferation; Gene Silencing; Mice, Inbred ICR; Morphogenesis; Nerve Tissue Proteins; RNA, Small Interfering; Tooth; Tooth Germ
PubMed: 27590885
DOI: 10.1007/s00441-016-2489-4 -
Dental Materials : Official Publication... Jan 2020Overview the development of human tooth; enamel, dentoenamel junction and dentin in regard to hierarchical structure property relationships and how these component... (Review)
Review
OBJECTIVE
Overview the development of human tooth; enamel, dentoenamel junction and dentin in regard to hierarchical structure property relationships and how these component structures can serve as templates for the design of tough materials.
METHODS
The dental, engineering and ceramic literature (PubMed, Science Direct, Google Scholar) covering the last 20years was over viewed regarding enamel and dentin characterization, structure-property studies, as well as, publications related to bioinspired materials with relationship to tooth structure. Relevant publications were selected for inclusion.
RESULTS
Enamel has been studied and modelled at 3 hierarchical levels, prism structure, parallel prism interactions and enamel decussation effects. Missing is a 4th level where the previous three hierarchies are combined with the 3D arrangement of these levels in enamel areas. Aspects of the enamel prism infrastructure and prism decussation have been used in 3D printing of Bouligand ceramic structures. The dento-enamel junction serves to arrest cracks and reduce the stress in enamel as a graded elastic modulus layer, leading to development of dental ceramics with increased strength and fatigue resistance. Dentin is a compliant structure that supports enamel mechanically and may, through providing interstitial fluid at the DEJ, allow repair of microcracks in enamel. Adequate models of dentin properties remain to be developed as it remains highly variable in tubule lumen size and the degree of mineral density around and between tubules.
SIGNIFICANCE
The structure of teeth, particularly the 4 hierarchical levels of enamel, creates a vital, hard, tough damage tolerant system for inspiring new materials.
Topics: Biomimetic Materials; Dental Enamel; Dentin; Hardness; Humans; Tooth
PubMed: 31543376
DOI: 10.1016/j.dental.2019.08.106 -
Wiadomosci Lekarskie (Warsaw, Poland :... 2022The aim: To study changes in the chemical composition of the tooth enamel surface when using hydrogen peroxide as a chemical component of the whitening system in...
OBJECTIVE
The aim: To study changes in the chemical composition of the tooth enamel surface when using hydrogen peroxide as a chemical component of the whitening system in combination with professional oral hygiene.
PATIENTS AND METHODS
Materials and methods: To achieve this goal, during the study, we studied the enamel of the teeth of the frontal area, which was removed for orthodontic and orthopedic indications. The age of the patients whose teeth were examined ranged from 18 to 44 years. In the experiment, we studied the chemical structure of enamel by a method thatcovered the selection of the study area, with the designation of areas for microanalysis, and subsequent elemental analysis in selected areas of the enamel.
RESULTS
Results and conclusions: Analyzing the results of this study, we can make assumptions about the impact of professional dental hygiene on the procedure of photo-whitening teeth based on 35% hydrogen peroxide gel and its subsequent impact on theother clinical indicators, which will depend on the characteristics of functional and structural resistance of the enamel.
Topics: Adolescent; Adult; Dental Enamel; Humans; Hydrogen Peroxide; Tooth; Tooth Bleaching; Young Adult
PubMed: 35962681
DOI: 10.36740/WLek202207114 -
Archives of Oral Biology May 2016To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a...
AIM
To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure.
MATERIALS AND METHODS
Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching.
RESULTS
Tooth shade changes were significant (p<0.001; 95% CI=-1/-8; power=99%), and most of the enamel layer was unaffected after bleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p<0.0001; power>99%).
CONCLUSIONS
Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward.
Topics: Dental Enamel; Hardness; Humans; Hydrogen Peroxide; Microscopy, Electron, Scanning; Microscopy, Polarization; Minerals; Molar, Third; Spectrophotometry; Surface Properties; Tooth Bleaching; Tooth Bleaching Agents; Tooth Demineralization; Tooth Permeability
PubMed: 26852001
DOI: 10.1016/j.archoralbio.2016.01.016