Circulating dentinal antigen-antibody immune complexes during orthodontic tooth movement in rats.

BACKGROUND: The immunogenic potential of dentin has been reported through dentin-reactive autoantibodies detection in human and animal model. This study aimed to investigate the formation and diagnostic value of immune complexes formation after autoantibodies production, and soluble dentin antigens levels associated to root resorption, in the course of orthodontic tooth movement, in rat experimental model. METHODS: Forty Wistar rats (n = 8 for each group) were submitted to orthodontic tooth movement, in which the maxillary right first molar was mesially moved by applying of 55 g of force for 3, 7, 14, or 21 days. Untreated group was used as control. Circulating autoantibodies to rat dentinal extract, immune complexes, and soluble dentinal antigen levels were determined by immunoenzyme assays. Additionally, dentinal antigens were analyzed by immunoblot. RESULTS: Higher serum dentin-reactive IgG and immune complex levels were detected in the 14- and 21-day groups (p < 0.05 and p < 0.001 respectively) but not in circulating dentinal antigen levels (p > 0.05), as compared to the control group. Reactivity was found to dentinal components with molecular mass (MM) ~120 and ~150 kDa, by immunoblot. CONCLUSION: This work represents the first evidence of immune complexes formation and circulating soluble dentin antigens associated to root resorption in orthodontic tooth movement. Immune complexes formation could be used to early diagnosis of external root resorption.

Dentin as a suitable bone substitute comparable to ß-TCP--an experimental study in mice.

Microvascular supply is of fundamental importance to the survival and integration of grafting. Since the autogenous bone is still the gold standard for osseous augmentation, the aim of this study was to analyze the initial osseous, angiogenic and inflammatory response and subsequent osseointegration after implantation of dentin and beta-tricalcium phosphate (ß-TCP) scaffolds into the calvaria chamber of balb/c mice comparing with bone. The vascularisation of perforated implants of dentin (n=8), ß-TCP (n=8) and isogenic calvarial bone (n=8) displaying pores similar in size and structure was analyzed in vivo using intravital fluorescence microscopy. In additional animals (n=24) the osseointegration of dentin, ß-TCP and bone implants was assessed by fluorochrome sequential labelling of growing bone for up to 12 weeks. Animals without implants served as controls. Intravital fluorescence microscopy revealed that implantation of bone substitutes caused an only mild inflammatory response. Comparable to isogenic bone both dentin and ß-TCP scaffolds were found nearly completely vascularized by day 22 and osseointegrated within 12 weeks. In conclusion, dentin and ß-TCP scaffolds are similar to isogenic bone in terms of inflammatory and neovascularization response, highlighting their potential utility in regeneration of bone defects.

Anti-dentine antibodies with root resorption during orthodontic treatment.

The aim of this study was to analyse serum IgG levels and salivary secretory IgA (sIgA) levels in human dentine extract (HDE) before (T0) and 6 months after (T6) orthodontic treatment and to correlate anti-HDE autoantibodies to root resorption. Fifty orthodontic patients were selected, 19 males (15.6 ± 8.5 years) and 31 females (21.4 ± 11.2 years), 19 in the mixed dentition (10.3 ± 1.9 years) and 31 in the permanent dentition (24.6 ± 9.9 years). Fifty individuals not undergoing orthodontic treatment matched by gender and age were selected as the controls. Periapical radiographs of the upper central incisors and saliva sampling were obtained of all patients at T0 and T6. Serum samples were collected from the permanent dentition patients (n = 31). Antibody levels were determined by means of immunoenzyme assay. At T6, root resorption was classified as grade 0 (no resorption), grade 1 (slight resorption), and grade 2 (moderate to severe resorption). Differences between antibody levels at T0 and T6 and among different grades of resorption were determined by paired t- and Kruskal-Wallis tests, respectively. Spearman's rank correlation coefficient was applied to detect correlation between sIgA and IgG levels, and logistic regression to determine the association of root resorption grade and the studied variables. Differences were considered significant at P < 0.05. Serum anti-HDE IgG levels decreased (P < 0.01) in grade 2 root resorption patients during treatment and was not correlated to salivary sIgA levels or other variables. Patients who had grade 2 root resorption at T6 showed higher levels of anti-HDE sIgA (P < 0.001). Anti-HDE sIgA levels at T0 and root shape were the main factors associated with the degree of root resorption. The results suggest that variations to systemic and local humoural immune response to dentine antigens may occur during orthodontic treatment. High levels of salivary sIgA before treatment were associated with more advanced lesions after 6 months of treatment.

Dentin phosphoprotein inhibits lipopolysaccharide-induced macrophage activation independent of its serine/aspartic acid-rich repeats.

OBJECTIVE: The objective of this study was to investigate the effects of dentin phosphoprotein (DPP) on lipopolysaccharide-induced inflammatory responses of macrophages in vitro. DESIGN: Wildtype and mutant recombinant dentin phosphoprotein (rDPP) proteins were generated using a mammalian expression system. Macrophages, phorbol 12-myristate 13-acetate-differentiated THP-1 cells, were stimulated with lipopolysaccharide in the absence or presence of rDPP proteins. After the 24-hr incubation, the inflammatory gene expression levels were examined by quantitative reverse-transcription polymerase chain reaction and the amount of secreted TNF-α protein was evaluated by enzyme-linked immunosorbent assay. Furthermore, the subcellular localization of exogenously added rDPP was examined by immunocytochemistry, and the direct binding of rDPP to lipopolysaccharide was quantified by solid-phase binding assay. RESULTS: rDPP dose-dependently reduced the expression of lipopolysaccharide-induced inflammatory genes, such as TNFα, IL-1ß, and IL-8, and TNF-α protein secretion from the macrophages. Furthermore, mutant rDPP having a shortened serine/aspartic acid-rich repeats (SDrr) was also able to inhibit lipopolysaccharide-induced inflammatory responses of macrophages. rDPP was localized adjacent to the cellular membrane rather than in the cytoplasm, and rDPP was able to bind to lipopolysaccharide. These results suggested that rDPP inhibited lipopolysaccharide-induced inflammatory responses by binding to lipopolysaccharide. CONCLUSIONS: In addition to the well-known functions of DPP for dentin mineralization that depend on the SDrr, we demonstrated that DPP possesses anti-inflammatory effects on lipopolysaccharide-stimulated macrophages that are independent of the SDrr.

Comprehensive Characterization of 2 Immature Teeth Treated with Regenerative Endodontic Procedures.

INTRODUCTION: Regeneration of the pulp-dentin complex is the penultimate goal of regenerative endodontic procedures (REPs). Histological outcomes have demonstrated reparative tissue formation in human teeth extracted post-REPs. However, lack of accurate characterization has precluded identification of the true nature of tissues formed post-REP. METHODS: Here, we present 2 case reports of tooth #29 and #9 treated with REPs and demonstrate their clinical, radiographic, and histological outcomes. RESULTS: Clinical outcomes revealed healing of apical periodontitis in both teeth and re-establishment of vitality responses in tooth #29. Moreover, radiographic assessments using 2D and 3D-volumetric analyses demonstrate considerable increase in root development for both teeth. Further, histological outcomes evaluated using Hematoxylin and Eosin and immunohistochemical staining demonstrates presence of vascular and lymphatic structures as well as immune cell markers indicative of regeneration of an immunocompetent pulp. Lastly, examination of hard tissue deposition shows dentin-like tissue in parts of tooth #29 demonstrating for the first time, regeneration of a pulp-dentin complex post-REP. CONCLUSIONS: Collectively, this is the first study demonstrating recapitulation of several tissues commonly found as part of a pulp-dentin complex in teeth treated with REPs.

The pulpal origin of immunoglobulins in dentin beneath caries: an immunohistochemical study.

Immunoglobulins localized in uninfected dentin beneath caries are thought to be protective, but their origin remains controversial. We reasoned that the localization and dominance of serum IgG1 would support the pulpal origin of the immunoglobulins while a predominance of secretory component (SC) bearing IgA1 and IgA2 would support their salivary origin. The prevalence and staining intensity of IgG1, IgA1, IgA2, IgM, and SC in uninfected dentinal tubules beneath shallow, deep caries, and noncaries teeth were examined immunohistologically. SC was only localized in caries, and IgG1 was the predominant subclass in uninfected dentinal tubules beneath shallow and deep caries, followed by IgA1. In noncaries teeth, IgG1 was localized on the pulpal end. The intensity of IgG1 was significantly higher than either IgA1 or IgA2 in both shallow and deep caries. Our data support the serum origin of immunoglobulins in uninfected dentin beneath caries.

Immunolocalization and distribution of proteoglycans in carious dentine.

BACKGROUND: Collagen type I, proteoglycans (PG) and non-collagenous proteins represent important building blocks of the dentine matrix. While different PGs have been identified in dentine, changes in the distribution of these macromolecules with the progression of caries have been poorly characterized. The aim of this study was to compare the immunolocalization of three small collagen-binding PGs (biglycan, fibromodulin and lumican) as well as collagen (types I and VI) in healthy versus carious dentine. METHODS: Longitudinal demineralized sections of extracted teeth were stained with antibodies recognizing specific PG core proteins and collagens, as well as glycosaminoglycans (GAGs) with toluidine blue. RESULTS: In healthy dentine, PGs appeared to be more abundant near the tubule walls and directly under the cusps. Conversely, in carious dentine, specific locations appeared to be more prone to PG degradation than others. These degradation patterns were well correlated with the progression of caries into the tissue, and also appeared to trigger interesting morphological changes in the tissue structure, such as the deformation of dentine tubules near highly infected areas and the lower concentration of PG in tertiary dentine. CONCLUSIONS: This study presents new insights into the involvement of PGs in the progression of caries.

Anti-dentine Salivary SIgA in young adults with a history of dental trauma in deciduous teeth.

Anti-dentin autoantibodies are associated with inflammatory root resorption in permanent teeth and are modulated by dental trauma and orthodontic force. However, it is not known whether deciduous tooth trauma can stimulate the development of a humoral immune response against dentin. The aim of this study was to evaluate the levels of salivary SIgA reactivity against human dentin extract in young adults with a history of trauma in the primary dentition. A sample of 78 patients, aged 18 to 25, who had completed an early childhood (0 to 5 years old) caries prevention program years earlier at the Universidade Estadual de Londrina Pediatric Clinic, underwent radiographic examination and salivary sampling. Anti-dentin SIgA levels were analyzed by immunoenzymatic assay and Western blotting. Although dental trauma to deciduous teeth had occurred in 34 (43.6%) of the patients, no differences in SIgA levels were detected between individuals who had experienced trauma and those who had not (p > 0.05). Multivariate regression analysis showed no association between dental trauma and SIgA levels (p > 0.05). Patients with a history of deciduous trauma presented low levels of anti-dentin antibodies, associated with orthodontic root resorption (p < 0.05). Western blot analysis showed that salivary antibodies recognized a single band of approximately 45 kDa in dentin extract. We concluded that salivary SIgA recognizes a specific component of the dentin matrix and that anti-dentin antibodies were not triggered by trauma to primary teeth. However, trauma to deciduous teeth may down-modulate SIgA in response to orthodontic root response.

Porphyromonas gingivalis 67-kDa fimbriae induced cytokine production and osteoclast differentiation utilizing TLR2.

Porphyromonas gingivalis, a major etiological agent of adult periodontitis, has two distinctly different types of fimbriae on the cell surface. The major fimbriae, which consist of a 41-kDa fimbrillin of P. gingivalis ATCC 33277, have been known to induce inflammatory cytokine production in murine peritoneal macrophages. In this study, we examined the effects of the minor fimbriae of P. gingivalis, composed of a 67-kDa fimbrillin, on cytokine production in murine peritoneal macrophages and the ability to induce osteoclast differentiation. Murine peritoneal macrophages were stimulated with P. gingivalis 67-kDa minor fimbriae for 24 h, then the levels of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 production were determined by enzyme-linked immunosorbent assay (ELISA). To estimate osteoclast differentiation, mouse osteoclast precursors were placed on dentine slices, and cultured with or without P. gingivalis 67-kDa minor fimbriae for 7 days. P. gingivalis 67-kDa minor fimbriae clearly induced IL-1beta, TNF-alpha and IL-6 production in mouse macrophages. Furthermore, pit formations on the dentine slices were significantly extended when the osteoclast precursors were incubated with P. gingivalis 67-kDa minor fimbriae. Pretreatment with anti-Toll-like receptor 2 (TLR2) antibody significantly inhibited IL-1beta, TNF-alpha and IL-6 induction (P<0.05) in mouse macrophages and pit-forming activity of osteoclast precursor cells stimulated with P. gingivalis 67-kDa minor fimbriae. These results suggest that P. gingivalis 67-kDa minor fimbriae may provoke host inflammatory response and be involved in periodontal tissue breakdown.

Immunohistochemical localization of HLA-DR-positive cells in unerupted and erupted normal and carious human teeth.

Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.

Dentinal response against carious invasion: localization of antibodies in odontoblastic body and process.

The pulpal origin of dentinal immunoglobulins was demonstrated by means of immunohistological methods. Immunoglobulins were located both in the cytoplasm of odontoblasts in pulp and at odontoblastic processes in dentin. Positive reactivity of the immunoglobulins to antigens was confirmed using peroxidase-immunized rabbits. IgG, IgA, IgM, C3, and C4 were observed on some invasive bacteria in human carious dentin.

Co-increase of nerve fibers and HLA-DR- and/or factor-XIIIa-expressing dendritic cells in dentinal caries-affected regions of the human dental pulp: an immunohistochemical study.

Neuro-immune interaction has been suggested to play some modulatory role in the immunodefense of the dentin/pulp complex. In this study, we performed a simultaneous immunohistochemical observation of neural elements and pulpal dendritic cells (PDCs) on human carious teeth, to obtain morphological evidence for neuro-immune interaction in response to dentinal tubule-derived carious stimuli. Human third molars bearing a pulp-exposure-free caries lesion were studied. Immunoperoxidase staining was performed with anti-HLA-DR, anti-coagulation factor XIIIa, and anti-CD14 as PDC markers, and anti-low-affinity nerve growth factor receptor (NGFR), anti-protein gene products 9.5, and anti-calcitonin gene-related peptide as nerve markers. The carious teeth usually exhibited localized accumulation of both PDCs and nerve fibers immunoreactive to each marker, in the para-odontoblastic region corresponding to the pulpal end of carious dentinal tubules. Semi-quantitative digital densitometry revealed that pixel numbers corresponding to factor-XIIIa- and NGFR-immunoreactivity were significantly higher in the carious regions than those in the non-carious regions of the same teeth as well as those in the corresponding regions of intact teeth. Classification of specimens with respect to caries depth showed that the co-increase was most apparent in teeth with superficial caries. The increase of PDCs was less pronounced in carious teeth with reparative dentin. These findings suggest that both pulpal nerves and PDCs respond promptly and actively to dentinal tubule-derived carious stimuli. The synchronized accumulation of the two structures suggests an increased opportunity for neuro-immune interaction that may be of significance in the modulation of pathological processes in the dental pulp.

Immunocytochemical analysis of dentin: a double-labeling technique.

Immunocytochemical analysis is a fundamental and selective technique for identifying different molecular components of human dental structure. The hypothesis tested here is that the application of different etching solutions on dentin does not hinder collagen fibrils and proteoglycans from maintaining their immunochemical antigenicity. Human dentin disks were treated with 0.5M of EDTA, citric acid, maleic acid, or phosphoric acid (for 15 or 30 s). A double-immunolabeling technique was performed to identify, simultaneously, collagen fibrils and chondroitin sulfate. The use of different acids resulted in different degrees of labeling. Maleic and citric acids revealed a diffuse and intense labeling for both collagen fibrils and proteoglycans. The use of phosphoric acid on dentin showed a massive coagulation of the proteoglycans (15 s) or very low labeling (30 s). These data clarify that the use of acids on dentin components is able to modify their antigenicity. Moreover, the double-labeling immunocytochemical technique allows understanding of the spatial relationships between the collagen fibrils and proteoglycans of the dentin matrix.

Defense responses of dentin/pulp complex to experimentally induced caries in rat molars: an immunohistochemical study on kinetics of pulpal Ia antigen-expressing cells and macrophages.

Experimental caries was induced in rats that were inoculated orally with Streptococcus mutants and maintained on a cariogenic diet. During the caries process, kinetics of the pulpal la antigen-expressing cells and macrophages was monitored immunohistochemically and was correlated with caries depth and the status of reparative dentin formation. Initial pulpal response was characterized by a localized accumulation of la antigen-expressing cells beneath the dentinal tubules communicating with the superficial caries. This was followed by a caries-depth related increase of la antigen-expressing cells and macrophages in the coronal pulp. The accumulation of these cells under the dentin was most apparent when the caries had progressed into the reparative dentin. These findings suggest that the response of la antigen-expressing cells to carious irritants triggers the defense reactions of the pulp. The intensity of the defense reactions may be correlated with the permeability of carious dentin.

Effect of injury on pulpal levels of immunoreactive substance P and immunoreactive calcitonin gene-related peptide.

Neuropeptides such as calcitonin gene-related peptide (CGRP) and substance P are present in dental pulp in relatively high concentrations. Previous studies have demonstrated that the staining density of immunoreactive CGRP (iCGRP) changes in dental pulp after tissue injury. This study evaluated injury-related changes in levels of both immunoreactive CGRP (iCGRP) and immunoreactive substance P (iSP) in dental pulp using radioimmunoassays. After pulpal exposure, iSP levels decreased to about 10% of baseline values, while iCGRP levels decreased to about 45% of baseline measures. After dentin exposure with acid etch, iSP levels decreased to about 10 to 20% of baseline measures, while iCGRP levels decreased to 60% of baseline values. For both forms of injury, iSP decreased to a greater extent than did iCGRP levels. Collectively, these findings indicate that pulpal neuropeptides undergo dynamic, injury-specific, and peptide-specific responses following trauma to dental pulp.

The effects of immunoglobulins on the convective permeability of human dentine in vitro.

Immunoglobulin molecules are localized in the dentinal tubules of non-carious and carious teeth, but their possible role in caries invasion is not understood. This study sought to examine the effects of immunoglobulin molecules on dentine permeability using a fluid-filtration method. Crown segments cut from impacted human third molars were treated by filtration with 100 micrograms/ml IgG, 100 micrograms/ml IgA or 30 micrograms/ml IgM under a constant pressure. Flow rates were recorded and percent changes in flow rate analysed over time. Filtrates collected at various times were tested for changes in immunoglobulin concentrations by an enzyme-linked immunosorbent assay, and the percent retention of immunoglobulins to dentine was calculated. There was a decreasing non-linear exponential relation between the percent changes in flow rate and filtration time for all three immunoglobulins. The percentage of retained immunoglobulins was significantly related to the filtration time for all three classes of immunoglobulins. Immunoglobulin retention contributed to significant changes in flow rate with time. These in vitro results indicate the potential mechanism of immunoglobulins in decreasing tabular permeability.

Effect of inferior alveolar nerve axotomy on immune cells and nerve fibres in young rat molars.

Denervation has been a useful approach to the investigation of interactions between nerve fibres and the pulp-dentine complex. Information on the immunological implications of axotomy is still lacking. The effect of axotomy on CD43+, CD4+, CD11b+ and I-A antigen-expressing cells in both the distal segment of the cut inferior alveolar nerve and in the first molar pulp of young rats was evaluated. Nerve fibres immunoreactive to protein gene product (PGP) 9.5, the neuropeptides substance P and calcitonin gene-related peptide (CGRP), and neuropeptide Y were visualized also by use of the avidin-biotin peroxidase complex method. Recruitment of macrophages was found in the distal segment of the sectioned inferior alveolar nerve 2 days after axotomy, with a further increase in number during the 6-day observation period. However, in the dental pulp, the number of CD43+, CD4+, CD11b+ and I-A antigen-expressing cells was almost unaffected. An almost complete sensory denervation of the first mandibular molar pulp was obtained 2 days after axotomy. After 6 days, the mesial part of the coronal pulp still remained denervated, while regenerated nerve fibres had reached both the root pulp and the distal part of the coronal pulp. Nerve fibres immunoreactive to neuropeptide Y were slightly reduced in density 2 days after axotomy, and after 6 days the localization of neuropeptide Y-immunoreactive fibres was changed compared to the control, with fibres also distributed in the odontoblast layer close to dentine. Hence, following axotomy in young rats, an almost complete sensory denervation is achieved in the first molar, whereas nerve fibres immunoreactive to neuropeptide Y change their distribution pattern, with fibres located close to the dentine after 6 days. Due to the almost unchanged number and distribution of immunocompetent cells in the pulp after axotomy, the young rat molar pulp may represent a suitable and useful experimental model to study neuro-immune interactions.

[Local immunity in dental caries in children]. / Sostoianie mestnogo immuniteta pri kariese zubov u detei.

Immune state was evaluated in 69 schoolchildren. In cases with dental caries, local immunity changes were evident with changes in immune globulins content. This is the first report on the presence of antigen to caries-afflicted dentin in the mixed saliva as detected by the complement binding technique. The course features of the disease were related to the salivary antibodies titer.

Inflammation and regeneration in the dentin-pulp complex: a double-edged sword.

Dental tissue infection and disease result in acute and chronic activation of the innate immune response, which is mediated by molecular and cellular signaling. Different cell types within the dentin-pulp complex are able to detect invading bacteria at all stages of the infection. Indeed, at relatively early disease stages, odontoblasts will respond to bacterial components, and as the disease progresses, core pulpal cells including fibroblasts, stems cells, endothelial cells, and immune cells will become involved. Pattern recognition receptors, such as Toll-like receptors expressed on these cell types, are responsible for detecting bacterial components, and their ligand binding leads to the activation of the nuclear factor-kappa B and p38 mitogen-activated protein (MAP) kinase intracellular signaling cascades. Subsequent nuclear translocation of the transcription factor subunits from these pathways will lead to proinflammatory mediator expression, including increases in cytokines and chemokines, which trigger host cellular defense mechanisms. The complex molecular signaling will result in the recruitment of immune system cells targeted at combating the invading microbes; however, the trafficking and antibacterial activity of these cells can lead to collateral tissue damage. Recent evidence suggests that if inflammation is resolved relatively low levels of proinflammatory mediators may promote tissue repair, whereas if chronic inflammation ensues repair mechanisms become inhibited. Thus, the effects of mediators are temporal context dependent. Although containment and removal of the infection are keys to enable dental tissue repair, it is feasible that the development of anti-inflammatory and immunomodulatory approaches, based on molecular, epigenetic, and photobiomodulatory technologies, may also be beneficial for future endodontic treatments.

Inflammation-regeneration interplay in the dentine-pulp complex.

OBJECTIVES: Dental tissue disease and trauma provides an excellent model for the interaction between tissue defence and regenerative processes and has application to many of the body's other tissues. Following dental tissue infection, characterised by caries, the molecular and cellular mediators of the immune/inflammatory processes clearly impact on the dental tissues' natural regenerative responses. This review of the literature was performed to better understand how these two processes interact and identify whether cross-talk may provide novel areas for future research and subsequent translation into clinical application. DATA AND SOURCES: A review of the literature was performed using the PubMed database resource and this was followed by extensive hand searching using reference lists from relevant articles. CONCLUSIONS: Frequently, the dental tissue inflammatory and regenerative processes are seen as both distinct and antagonistic and subsequently have often been studied in isolation; however, both direct and indirect data are now emerging which indicate significant inter-relationship. Whilst the ensuing inflammatory process will result in dental tissue breakdown and molecular signalling which may impede regeneration, low grade inflammation, potentially induced by mechanical trauma and tissue necrosis, may promote regenerative mechanisms, including angiogenic and stem cell processes. Notably, the locally derived growth factors, neuropeptides, cytokines and chemokines, released from the host dentine matrix and by resident pulpal cells, immune cells, neurons and/or dying cells, will modulate defence and repair processes within the tissue.