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International Journal of Molecular... Feb 2021The macroscopic and microscopic anatomy of the oral cavity is complex and unique in the human body. Soft-tissue structures are in close interaction with mineralized... (Review)
Review
The macroscopic and microscopic anatomy of the oral cavity is complex and unique in the human body. Soft-tissue structures are in close interaction with mineralized bone, but also dentine, cementum and enamel of our teeth. These are exposed to intense mechanical and chemical stress as well as to dense microbiologic colonization. Teeth are susceptible to damage, most commonly to caries, where microorganisms from the oral cavity degrade the mineralized tissues of enamel and dentine and invade the soft connective tissue at the core, the dental pulp. However, the pulp is well-equipped to sense and fend off bacteria and their products and mounts various and intricate defense mechanisms. The front rank is formed by a layer of odontoblasts, which line the pulp chamber towards the dentine. These highly specialized cells not only form mineralized tissue but exert important functions as barrier cells. They recognize pathogens early in the process, secrete antibacterial compounds and neutralize bacterial toxins, initiate the immune response and alert other key players of the host defense. As bacteria get closer to the pulp, additional cell types of the pulp, including fibroblasts, stem and immune cells, but also vascular and neuronal networks, contribute with a variety of distinct defense mechanisms, and inflammatory response mechanisms are critical for tissue homeostasis. Still, without therapeutic intervention, a deep carious lesion may lead to tissue necrosis, which allows bacteria to populate the root canal system and invade the periradicular bone via the apical foramen at the root tip. The periodontal tissues and alveolar bone react to the insult with an inflammatory response, most commonly by the formation of an apical granuloma. Healing can occur after pathogen removal, which is achieved by disinfection and obturation of the pulp space by root canal treatment. This review highlights the various mechanisms of pathogen recognition and defense of dental pulp cells and periradicular tissues, explains the different cell types involved in the immune response and discusses the mechanisms of healing and repair, pointing out the close links between inflammation and regeneration as well as between inflammation and potential malignant transformation.
Topics: Animals; Antigens, Neoplasm; Carcinogenesis; Carcinoma, Squamous Cell; Chemokines; Complement System Proteins; Dental Caries; Dental Pulp; Dentin; Fibroblasts; Humans; Intracellular Signaling Peptides and Proteins; Mesenchymal Stem Cells; Mouth Neoplasms; Nerve Net; Neuropeptides; Nitric Oxide; Odontoblasts; Periapical Granuloma; Periapical Periodontitis; Periapical Tissue; Pulpitis; Radicular Cyst
PubMed: 33540711
DOI: 10.3390/ijms22031480 -
BMC Oral Health Aug 2020Though dentin hypersensitivity (DHS) is one of the most common complaints from patients in dental clinics, there are no universally accepted guidelines for differential... (Review)
Review
Though dentin hypersensitivity (DHS) is one of the most common complaints from patients in dental clinics, there are no universally accepted guidelines for differential diagnosis as well as selection of reliable treatment modalities for this condition. The neurosensory mechanisms underlying DHS remain unclear, but fluid movements within exposed dentinal tubules, i.e., the hydrodynamic theory, has been a widely accepted explanation for DHS pain. As several dental conditions have symptoms that mimic DHS at different stages of their progression, diagnosis and treatment of DHS are often confusing, especially for inexperienced dental practitioners. In this paper we provide an up-to-date review on risk factors that play a role in the development and chronicity of DHS and summarize the current principles and strategies for differential diagnosis and management of DHS in dental practices. We will outline the etiology, predisposing factors and the underlying putative mechanisms of DHS, and provide principles and indications for its diagnosis and management. Though desensitization remains to be the first choice for DHS for many dental practitioners and most of desensitizing agents reduce the symptoms of DHS by occluding patent dentinal tubules, the long-term outcome of such treatment is uncertain. With improved understanding of the underlying nociceptive mechanisms of DHS, it is expected that promising novel therapies will emerge and provide more effective relief for patients with DHS.
Topics: Dentin; Dentin Sensitivity; Dentists; Humans; Professional Role; Risk Factors
PubMed: 32762733
DOI: 10.1186/s12903-020-01199-z -
Cells Jul 2022BMP signaling plays an important role in dentin development. BMPs and antagonists regulate odontoblast differentiation and downstream gene expression via canonical Smad... (Review)
Review
BMP signaling plays an important role in dentin development. BMPs and antagonists regulate odontoblast differentiation and downstream gene expression via canonical Smad and non-canonical Smad signaling pathways. The interaction of BMPs with their receptors leads to the formation of complexes and the transduction of signals to the canonical Smad signaling pathway (for example, BMP ligands, receptors, and Smads) and the non-canonical Smad signaling pathway (for example, MAPKs, p38, Erk, JNK, and PI3K/Akt) to regulate dental mesenchymal stem cell/progenitor proliferation and differentiation during dentin development and homeostasis. Both the canonical Smad and non-canonical Smad signaling pathways converge at transcription factors, such as Dlx3, Osx, Runx2, and others, to promote the differentiation of dental pulp mesenchymal cells into odontoblasts and downregulated gene expressions, such as those of DSPP and DMP1. Dysregulated BMP signaling causes a number of tooth disorders in humans. Mutation or knockout of BMP signaling-associated genes in mice results in dentin defects which enable a better understanding of the BMP signaling networks underlying odontoblast differentiation and dentin formation. This review summarizes the recent advances in our understanding of BMP signaling in odontoblast differentiation and dentin formation. It includes discussion of the expression of BMPs, their receptors, and the implicated downstream genes during dentinogenesis. In addition, the structures of BMPs, BMP receptors, antagonists, and dysregulation of BMP signaling pathways associated with dentin defects are described.
Topics: Animals; Bone Morphogenetic Proteins; Dentin; Humans; Mice; Odontoblasts; Phosphatidylinositol 3-Kinases; Signal Transduction
PubMed: 35883659
DOI: 10.3390/cells11142216 -
Indian Journal of Dental Research :... 2020Abfraction is a loss of tooth structure along the gingival margin and manifests with different clinical appearances. It has multifactorial etiology and may occur due to... (Review)
Review
BACKGROUND
Abfraction is a loss of tooth structure along the gingival margin and manifests with different clinical appearances. It has multifactorial etiology and may occur due to normal and abnormal tooth function and may also be accompanied by pathological wear, such as abrasion and erosion. The theory behind the abfraction is that the tooth flexure in the cervical area is caused due to occlusal compressive forces and tensile stresses. This results in the fractures in the hydroxyapatite (HA) crystals. It is also caused by the low packing density of the Hunter-Schreger band (HSB) at the cervical area. Unfortunately, there is a lack of evidence regarding the outcome of abfraction with or without intervention. The aim of this review is to collect clinical information from the literature and discuss the etiology, pathogenesis, clinical representation, and management. Also, search databases for clinical studies that describe the role of sclerotic dentine in non-carious cervical lesions (NCCLs) are becoming a clinical challenge.
METHODS
The literature was searched that described the etiology, pathogenesis, clinical representation, and management of the abfraction lesions. Also, a specific question regarding the formation of sclerotic dentin in the NCCL lesion was described and searched for evidence that challenges etching, bonding, and successfully restoring NCCLs. The databases PUBMED, SCOPUS, MEDLINE, WEB of SCIENCE, and EMBASE were searched using the key terms. The inclusion criteria were the randomized controlled clinical trial, cohort studies, and cross-sectional studies that aimed at determining the role of sclerotic dentine in NCCLs and its effect on etching, bonding.
RESULTS
One clinical study was retrieved according to the PRISMA flowchart and PICO format. The longer etching time, total-etch adhesive system, and EDTA pre-treatment of the sclerotic dentin of cervical wedge-shaped defects could improve the bonding strength in lesions like NCCL's.
CONCLUSION
In conclusion, clinical challenges that occur due to NCCLs are better managed by a proper understanding of factors like etiopathogenesis, ultra-structure of enamel, and dentine and their effect on the bonding of restorations of the tooth.
Topics: Cross-Sectional Studies; Dental Enamel; Dentin; Humans; Tooth Cervix; Tooth Diseases
PubMed: 32436913
DOI: 10.4103/ijdr.IJDR_863_18 -
Journal of Endodontics Nov 2021Although many clinical studies have reported on the prevalence of dental pain, far fewer studies have focused on the mechanisms of dental pain. This is an important gap... (Review)
Review
INTRODUCTION
Although many clinical studies have reported on the prevalence of dental pain, far fewer studies have focused on the mechanisms of dental pain. This is an important gap because increased understanding of dental pain mechanisms may lead to improved diagnostic tests or therapeutic interventions. The aim of this study was to comprehensively review the literature on the mechanisms of dentinal sensitivity.
METHODS
PubMed and Ovid were searched for articles that addressed dentinal pain and or pulpal sensitivity. Because of the breadth of research ranging from cellular/molecular studies to clinical trials, a narrative review on the mechanisms of dentinal sensitivity was constructed based on the literature.
RESULTS
Five various mechanisms for dentinal sensitivity have been proposed: (1) the classic hydrodynamic theory, (2) direct innervation of dentinal tubules, (3) neuroplasticity and sensitization of nociceptors, (4) odontoblasts serving as sensory receptors, and (5) algoneurons.
CONCLUSIONS
These theories are not mutually exclusive, and it is possible that several of them contribute to dentinal sensitivity. Moreover, pulpal responses to tissue injury may alter the relative contribution of these mechanisms. For example, pulpal inflammation may lead to neuronal sprouting and peripheral sensitization. Knowledge of these mechanisms may prompt the development of therapeutic drugs that aim to disrupt these mechanisms, leading to more effective treatments for pulpal pain.
Topics: Dental Pulp; Dentin; Dentin Sensitivity; Humans; Nociceptors; Odontoblasts; Pain
PubMed: 34302871
DOI: 10.1016/j.joen.2021.07.011 -
Tissue Engineering and Regenerative... Aug 2022Dentin is a permeable tubular composite and complex structure, and in weight, it is composed of 20% organic matrix, 10% water, and 70% hydroxyapatite crystalline matrix.... (Review)
Review
BACKGROUND
Dentin is a permeable tubular composite and complex structure, and in weight, it is composed of 20% organic matrix, 10% water, and 70% hydroxyapatite crystalline matrix. Demineralization of dentin with gradient concentrations of ethylene diamine tetraacetic acid, 0.6 N hydrochloric acid, or 2% nitric acid removes a major part of the crystalline apatite and maintains a majority of collagen type I and non-collagenous proteins, which creates an osteoinductive scaffold containing numerous matrix elements and growth factors. Therefore, demineralized dentin should be considered as an excellent naturally-derived bioactive material to enhance dental and alveolar bone tissues regeneration.
METHOD
The PubMed and Midline databases were searched in October 2021 for the relevant articles on treated dentin matrix (TDM)/demineralized dentin matrix (DDM) and their potential roles in tissue regeneration.
RESULTS
Several studies with different study designs evaluating the effect of TDM/DDM on dental and bone tissues regeneration were found. TDM/DDM was obtained from human or animal sources and processed in different forms (particles, liquid extract, hydrogel, and paste) and different shapes (sheets, slices, disc-shaped, root-shaped, and barrier membranes), with variable sizes measured in micrometers or millimeters, demineralized with different protocols regarding the concentration of demineralizing agents and exposure time, and then sterilized and preserved with different techniques. In the act of biomimetic acellular material, TDM/DDM was used for the regeneration of the dentin-pulp complex through direct pulp capping technique, and it was found to possess the ability to activate the odontogenic differentiation of stem cells resident in the pulp tissues and induce reparative dentin formation. TDM/DDM was also considered for alveolar ridge and maxillary sinus floor augmentations, socket preservation, furcation perforation repair, guided bone, and bioroot regenerations as well as bone and cartilage healing.
CONCLUSION
To our knowledge, there are no standard procedures to adopt a specific form for a specific purpose; therefore, future studies are required to come up with a well-characterized TDM/DDM for each specific application. Likely as decellularized dermal matrix and prospectively, if the TDM/DDM is supplied in proper consistency, forms, and in different sizes with good biological properties, it can be used efficiently instead of some widely-used regenerative biomaterials.
Topics: Animals; Bone Regeneration; Bone and Bones; Dentin; Humans; Sinus Floor Augmentation
PubMed: 35429315
DOI: 10.1007/s13770-022-00438-4 -
Journal of Dentistry Dec 2021We aimed to assess the impact of an artificial intelligence (AI)-based diagnostic-support software for proximal caries detection on bitewing radiographs. (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
We aimed to assess the impact of an artificial intelligence (AI)-based diagnostic-support software for proximal caries detection on bitewing radiographs.
METHODS
A cluster-randomized cross-over controlled trial was conducted. A commercially available software employing a fully convolutional neural network for caries detection (dentalXrai Pro, dentalXrai Ltd.) was randomly employed by 22 dentists, supporting their caries detection on 20 bitewings randomly chosen from a pool of 140 bitewings, with 10 bitewings randomly being supported by AI and 10 not. The reference test had been established by 4 + 1 independent experts in a pixelwise fashion. Caries was subgrouped as enamel, early dentin and advanced dentin caries, and accuracy and treatment decisions for each caries lesion assessed.
RESULTS
Dentists with AI showed a significantly higher mean (95% CI) area under the Receiver-Operating-Characteristics curve (0.89; 0.87-0.90) than those without AI (0.85; 0.83-0.86; p<0.05), mainly as their sensitivity was significantly higher (0.81; 0.74-0.87 compared with 0.72; 0.64-0.79; p<0.05) while the specificity was not significantly affected (p>0.05). This increase in sensitivity was found for enamel, but not early or advanced dentin lesions. Higher sensitivity came with an increase in non-invasive, but also invasive treatment decisions (p<0.05).
CONCLUSION
AI can increase dentists' diagnostic accuracy but may also increase invasive treatment decisions.
CLINICAL SIGNIFICANCE
AI can increase dentists' diagnostic accuracy, mainly via increasing their sensitivity for detecting enamel lesions, but may also increase invasive therapy decisions. Differences in the effects of AI for different dentists should be explored, and dentists should be guided as to which therapy to choose when detecting caries lesions using AI support.
Topics: Artificial Intelligence; Dental Caries; Dental Caries Susceptibility; Dental Enamel; Dentin; Humans; Neural Networks, Computer; Sensitivity and Specificity
PubMed: 34656656
DOI: 10.1016/j.jdent.2021.103849 -
Journal of Dentistry Sep 2022Preservation of pulpal vitality in immature permanent teeth with deep carious lesions is essential to enable further root development and apical closure. This systematic... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
Preservation of pulpal vitality in immature permanent teeth with deep carious lesions is essential to enable further root development and apical closure. This systematic review aimed to evaluate the evidence regarding the efficacy, presented clinical and radiographic success, and bacteriological outcomes of techniques and materials used for deep caries management in vital immature permanent teeth.
DATA
Randomised controlled trials evaluating Vital Pulp Therapy (VPT) for deep caries in immature permanent posterior teeth without history of irreversible pulpitis, and a follow up period of ≥12 months were included. Study characteristics and outcomes of all included studies were summarized. Cochrane's Risk-of-bias tool 2.0 was used to assess the quality of eligible studies. Meta-analyses using a random effects model was performed.
SOURCES
Electronic databases PubMed, Medline, Embase, LILACS, CENTRAL and Cochrane Library were searched, followed by a manual search.
STUDY SELECTION
Twelve papers were included into the review. Overall success rates were 98%, 93.5%, 93.6% for direct pulp cap (DPC), indirect pulp cap (IPC) and pulpotomy (PP) respectively. Regardless of VPT technique, there were no significant differences between clinical and radiographic success rates. Completion of root development was achieved in more than 83% of the cases in all VPT techniques.
CONCLUSIONS
All treatment modalities for PP were equally efficient with high overall success rates. Biodentine showed high success rates regardless of technique. No significant differences were found in the clinical and radiographic success rates between various follow-up intervals. There are no clear conclusions regarding superiority of either VPT technique on apical closure.
CLINICAL SIGNIFICANCE
This manuscript systematically evaluates the evidence and summarises all available data on each vital pulp therapy technique and materials used in treatment of deep caries in immature permanent teeth with vital pulps. The limitations in the current scientific literature and recommendations for future research are also highlighted.
Topics: Dental Caries; Dental Caries Susceptibility; Dental Pulp Capping; Dentin; Dentition, Permanent; Humans; Pulpotomy
PubMed: 35793760
DOI: 10.1016/j.jdent.2022.104214 -
Clinical Oral Investigations Oct 2019To define an expert Delphi consensus on when to intervene in the caries process and on existing carious lesions using non- or micro-invasive, invasive/restorative or...
OBJECTIVES
To define an expert Delphi consensus on when to intervene in the caries process and on existing carious lesions using non- or micro-invasive, invasive/restorative or mixed interventions.
METHODS
Non-systematic literature synthesis, expert Delphi consensus process and expert panel conference.
RESULTS
Carious lesion activity, cavitation and cleansability determine intervention thresholds. Inactive lesions do not require treatment (in some cases, restorations will be placed for reasons of form, function and aesthetics); active lesions do. Non-cavitated carious lesions should be managed non- or micro-invasively, as should most cavitated carious lesions which are cleansable. Cavitated lesions which are not cleansable usually require invasive/restorative management, to restore form, function and aesthetics. In specific circumstances, mixed interventions may be applicable. On occlusal surfaces, cavitated lesions confined to enamel and non-cavitated lesions radiographically extending deep into dentine (middle or inner dentine third, D2/3) may be exceptions to that rule. On proximal surfaces, cavitation is hard to assess visually or by using tactile methods. Hence, radiographic lesion depth is used to determine the likelihood of cavitation. Most lesions radiographically extending into the middle or inner third of the dentine (D2/3) can be assumed to be cavitated, while those restricted to the enamel (E1/2) are not cavitated. For lesions radiographically extending into the outer third of the dentine (D1), cavitation is unlikely, and these lesions should be managed as if they were non-cavitated unless otherwise indicated. Individual decisions should consider factors modifying these thresholds.
CONCLUSIONS
Comprehensive diagnostics are the basis for systematic decision-making on when to intervene in the caries process and on existing carious lesions.
CLINICAL RELEVANCE
Carious lesion activity, cavitation and cleansability determine intervention thresholds. Invasive treatments should be applied restrictively and with these factors in mind.
Topics: Consensus; Delphi Technique; Dental Caries; Dental Enamel; Dentin; Esthetics, Dental; Humans
PubMed: 31444695
DOI: 10.1007/s00784-019-03058-w -
Journal of Biomechanics Aug 2022Investigations into teeth mechanical properties provide insight into physiological functions and pathological changes. This study sought to 1) quantify the spatial...
Investigations into teeth mechanical properties provide insight into physiological functions and pathological changes. This study sought to 1) quantify the spatial distribution of elastic modulus, hardness and the microstructural features of dog dentin and to 2) investigate quantitative relationships between the mechanical properties and the complex microstructure of dog dentin. Maxillary canine teeth of 10 mature dogs were sectioned in the transverse and vertical planes, then tested using nanoindentation and scanning electron microscopy (SEM). Microstructural features (dentin area fraction and dentinal tubule density) and mechanical properties (elastic modulus and hardness) were quantified. Results demonstrated significant anisotropy and spatial variation in elastic modulus, hardness, dentin area fraction and tubule density. These spatial variations adhered to a consistent distribution pattern; hardness, elastic modulus and dentin area fraction generally decreased from superficial to deep dentin and from crown tip to base; tubule density generally increased from superficial to deep dentin. Poor to moderate correlations between microstructural features and mechanical properties (R = 0.032-0.466) were determined. The results of this study suggest that the other constituents may contribute to the mechanical behavior of mammalian dentin. Our results also present several remaining opportunities for further investigation into the roles of organic components (e.g., collagen) and mineral content on dentin mechanical behavior.
Topics: Animals; Dentin; Dogs; Elastic Modulus; Hardness; Mammals; Microscopy, Electron, Scanning; Structure-Activity Relationship; Tooth
PubMed: 35834939
DOI: 10.1016/j.jbiomech.2022.111218