Quantitative analysis of immunoglobulins and inflammatory factors in human pulpal blood from exposed pulps

Discriminatory performance of the pulpal inflammatory biomarkers; Interleukin-8 and TNF-α in patients with symptoms indicative of reversible and irreversible pulpitis: A diagnostic accuracy study

AIM

The success of vital pulp treatment (VPT) procedures is dependent on an accurate diagnosis of the pulpal inflammatory condition. Compared with current subjective pulpal diagnostic tests, inflammatory molecular biomarkers involved in the pathogenesis of pulpitis represent potential objective indicators of the degree of pulpal inflammation. Therefore, the aim of this study was to quantify level of inflammatory biomarkers - Interleukin 8 (IL-8) and TNF-α in patients diagnosed with reversible pulpitis (RP), irreversible pulpitis (IR) and normal pulp (NP) and investigate their diagnostic accuracy in differentiating between healthy and inflamed conditions.

METHODOLOGY

This prospective, cross-sectional study enrolled 72 patients aged 14-53 years with extremely deep carious lesions after establishing a clinical diagnosis of RP (n = 42), symptomatic IR (n = 22) and NP (n = 8). 50 μL of pulpal blood sample was collected from all the patients using a micropipette after pulpal exposure. The level of IL-8 and TNF-α was assessed in pg/mL using enzyme-linked immunosorbent assays. Mann-Whitney U test was applied to establish the association between IL-8/TNF-α level and degree of pulp inflammation. Receiver operating curve (ROC) analysis was carried out to calculate area under the curve (AUC) for RP versus IR. Cut-off values were established using Youden's index.

RESULTS

IL-8 and TNF-α levels differed significantly between RP and IR groups (p ≤ .001). The median value of IL-8 in RP and IP groups was 259.8 pg/mL [187.5-310.0] and 1357.8 pg/mL [1036.7-2177.6] respectively. The AUC-ROC curve for RP versus IR was 0.997 with 95.5% sensitivity and 99.76% specificity. The median value of TNF-α in RP and IR groups was 75.4 pg/mL [62.7-95.8] and 157.6 pg/mL [94.1-347.3]. The AUC-ROC curve for TNF-α was 0.812 with a sensitivity and specificity of 59.1% and 92.1%, respectively. IL-8 and TNF-α levels were below detection levels for all NP samples.

CONCLUSION

This study showed that pulpal blood could provide an excellent medium for establishing pulpal diagnosis under extremely deep carious lesions. The selected cytokines, IL-8 and TNF-α, demonstrated excellent discriminatory performance for reversible and irreversible pulpitis. Future studies should correlate the IL-8/TNF-α levels with VPT treatment outcomes.

Molecular biomarkers for objective assessment of symptomatic pulpitis: A systematic review and meta-analysis

BACKGROUND

Inflammatory biomarkers are potentially useful targets for pulpal diagnostic tests that can identify pulp status and predict vital pulp treatment (VPT) outcome, however, their accuracy is unknown.

OBJECTIVES

(1) Calculate sensitivity, specificity and diagnostic odds ratio (DOR) of previously investigated pulpitic biomarkers; (2) Determine if biomarker levels discriminate between clinical diagnoses of pulpitis based on the presence or absence of spontaneous pain (3) Evaluate if biomarker level can predict VPT outcome.

METHODS

Searches: PubMed/MEDLINE, Ovid SP, Cochrane Central Register of Controlled Trials (CENTRAL), International Clinical Trials Registry Platform (ICTRP), ClinicalTrials.gov, Embase, Web of Science and Scopus in May 2023.

INCLUSION

prospective and retrospective observational studies and randomized trials. Participants were humans with vital permanent teeth and a well-defined pulpal diagnosis.

EXCLUSION

deciduous teeth, in vitro and animal studies. Risk of bias was assessed with modified-Downs and Black quality assessment checklist. Meta-analysis was performed using bivariate random effect model in Meta-DiSc 2.0 and RevMan and the quality of the evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

Fifty-six studies were selected, reporting >70 individual biomolecules investigating pulpal health and disease at the gene and protein level. Most studies were of low and fair quality. Among the biomolecules investigated, IL-8 and IL-6 demonstrated a level of diagnostic accuracy with high sensitivity, specificity and DOR to discriminate between healthy pulps and those exhibiting spontaneous pain suggestive of IRP (low-certainty evidence). However, none was shown to have high DOR and the ability to discriminate between pulpitic states (very low certainty evidence). Limited data suggests high levels of matrix metalloproteinase 9 correlate with poorer outcomes of full pulpotomy.

DISCUSSION

The inability of identified molecular inflammatory markers to discriminate between dental pulps with spontaneous and non-spontaneous pain should shift the focus to improved study quality or the pursuit of other molecules potentially associated with healing and repair.

CONCLUSIONS

Low-quality evidence suggests IL-8 and IL-6 demonstrated level of diagnostic accuracy to discriminate between healthy pulps and those exhibiting spontaneous pain. There is a need for standardized biomarker diagnostic and prognostic studies focusing on solutions that can accurately determine the degree of pulp inflammation.

REGISTRATION

PROSPERO CRD42021259305.

Evaluation of the Effect of Common Analgesics on Pulpal Sensibility Tests: A Clinical Trial

INTRODUCTION

Accurate diagnosis is one of the most important steps before endodontic treatment. The aim of this study was to assess the effect of 2 commonly used analgesics namely ibuprofen and acetaminophen on the cold and electric pulp test (EPT) results in participants with symptomatic irreversible pulpitis (SIP).

METHODS

This clinical trial evaluated 41 participants with pain due to SIP. The cold test and EPT were performed for teeth with SIP, and also for the corresponding tooth with healthy pulp in the contralateral quadrant. The participants then received 500 mg acetaminophen, 400 mg ibuprofen, or the placebo in the 3 groups. The cold test and EPT were repeated at 20, 40, and 60 minutes after medication intake, and the results were compared with the pretreatment values.

RESULTS

In the acetaminophen group, the results of cold test significantly decreased 40 (P < .05), and 60 (P < .05) minutes after analgesic intake in teeth with SIP and after 40 minutes (P < .05) in the corresponding contralateral teeth with healthy pulp. In the ibuprofen group, the cold test results significantly decreased at 20 (P < .05), 40 (P < .05), and 60 (P < .05) minutes after analgesic intake in teeth with SIP and after 40 minutes (P < .05) in the corresponding contralateral teeth with healthy pulp. The EPT results were not significantly affected by the studied analgesics at any time point (P > .05). There was no significant difference among the study groups regarding sex (P > .05).

CONCLUSION

It appears that both acetaminophen and ibuprofen can affect the pulpal response to the cold sensibility test. However, the studied medications had no significant effect on the EPT results. Therefore, dental clinicians should be aware of the possible effects of such medications on the cold test response.

Caffeic Acid Phenethyl Ester Induces Vascular Endothelial Growth Factor Production and Inhibits CXCL10 Production in Human Dental Pulp Cells

The survival rate of root non-vital teeth is lower than that of vital teeth. Therefore, to preserve the dental pulp is very important. The vascular endothelial growth factor (VEGF) is the most potent angiogenic factor involved in the vitality of dental pulp including reparative dentin formation. Caffeic acid phenethyl ester (CAPE) is a physiologically active substance of propolis and has some bioactivities such as anti-inflammatory effects. However, there are no reports on the effects of CAPE on dental pulp inflammation. In this study, we investigated the effects of CAPE on VEGF and inflammatory cytokine production in human dental pulp cells (HDPCs) to apply CAPE to an ideal dental pulp protective agent. We found that CAPE induced VEGF production from HDPCs. Moreover, CAPE induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases (ERK), and stress-activated protein kinase/c-Jun N-terminal kinase (SAP/JNK) in HDPCs. Furthermore, CAPE inhibited C-X-C motif chemokine ligand 10 (CXCL10) production in Pam3CSK4- and tumor necrosis factor-alpha (TNF-α)-stimulated HDPCs. In conclusion, these results suggest that CAPE might be useful as a novel biological material for vital pulp therapy by exerting the effects of VEGF production and anti-inflammatory activities.

A critical analysis of research methods and experimental models to study pulpitis

Pulpitis is the inflammatory response of the dental pulp to a tooth insult, whether it is microbial, chemical, or physical in origin. It is traditionally referred to as reversible or irreversible, a classification for therapeutic purposes that determines the capability of the pulp to heal. Recently, new knowledge about dental pulp physiopathology led to orientate therapeutics towards more frequent preservation of pulp vitality. However, full adoption of these vital pulp therapies by dental practitioners will be achieved only following better understanding of cell and tissue mechanisms involved in pulpitis. The current narrative review aimed to discuss the contribution of the most significant experimental models developed to study pulpitis. Traditionally, in vitro two(2D)- or three(3D)-dimensional cell cultures or in vivo animal models were used to analyse the pulp response to pulpitis inducers at cell, tissue or organ level. In vitro 2D cell cultures were mainly used to decipher the specific roles of key actors of pulp inflammation such as bacterial by-products, pro-inflammatory cytokines, odontoblasts or pulp stem cells. However, these simple models did not reproduce the 3D organisation of the pulp tissue and, with rare exceptions, did not consider interactions between resident cell types. In vitro tissue/organ-based models were developed to better reflect the complexity of the pulp structure. Their major disadvantage is that they did not allow the analysis of blood supply and innervation participation. On the contrary, in vivo models have allowed researchers to identify key immune, vascular and nervous actors of pulpitis and to understand their function and interplay in the inflamed pulp. However, inflammation was mainly induced by iatrogenic dentine drilling associated with simple pulp exposure to the oral environment or stimulation by individual bacterial by-products for short periods. Clearly, these models did not reflect the long and progressive development of dental caries. Lastly, the substantial diversity of the existing models makes experimental data extrapolation to the clinical situation complicated. Therefore, improvement in the design and standardization of future models, for example by using novel molecular biomarkers, databased models and artificial intelligence, will be an essential step in building an incremental knowledge of pulpitis in the future.

A Mini Review: The Potential Biomarkers for Non-invasive Diagnosis of Pulpal Inflammation

For assessing the adequacy of vital pulp therapy for an inflamed pulp, the use of non-invasive diagnostic tools is necessary to avoid further damage to the teeth. Detection of biomarkers that are indicative of the inflammatory status in pulp can be a promising tool for this purpose. These biomarkers need to be reliably correlated with pulpal inflammation and to be easily detected without pulp exposure. This mini-review article aims to review biomarkers that are present in gingival crevicular fluid (GCF) in inflamed pulp conditions. Several studies have reported the availability of various biomarkers including cytokines, proteases, elastase, neuropeptides, and growth factors. Non-invasive pulpal diagnostic methods will be useful as well to determine reversibility, irreversibility, or necrosis of inflamed pulp. These types of molecular diagnoses via analyzing the proteome have revolutionized the medical field, and are one of the most promising empirical methodologies that a clinician can utilize for the proactive identification of pulpal disease.

Comparison of ADAMTS Levels in Pulp Tissue Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth

AIM

The aim of this study was to compare the levels of different ADAMTS (-1,-4, and -9) related to the breakdown of the proteoglycans and TIMP-3 levels that inhibit ADAMTS in the extra cellular matrix (ECM) of healthy pulp and symptomatic irreversible pulpitis.

METHODS

Pulp tissue samples diagnosed with healthy and symptomatic irreversible pulpitis were collected from 48 participants. Healthy and inflamed pulps were directly transferred to Eppendorf® tubes and stored at -80 °C (Nüve-DF490, Ankara, Türkiye) until further use. Routine root canal treatment procedures for the teeth were performed, after which the treatment process was completed. The levels of ADAMTS-1, ADAMTS-4, ADAMTS-9, and TIMP-3 were measured in supernatants of human dental pulp tissue extracts using ELISA kits (USCN, Wuhan, China). Independent sample t test and one-way analysis of variance (ANOVA) were used for parametric data, Kruskal-Wallis and Mann-Whitney U tests were used for non-parametric data.

RESULTS

There was a statistically significant difference between ADAMTS-1, ADAMTS-9 and TIMP-3 levels of the healthy pulp and pulpitis groups (p < 0.05), but there was no significant difference for ADAMTS-4 levels (p ˃ 0.05). It was found that the levels of ADAMTS-1 and ADAMTS-9 were higher in the pulpitis group compared to the healthy pulp group, while the TIMP-3 level decreased (p < 0.05).

CONCLUSION

As a result of this study, it was concluded that ADAMTS-1, ADAMTS-9 and TIMP-3 might have a role in pulpal inflammation, while ADAMTS-4 was not related to pulpal inflammation.

Effect of treatment with resiniferatoxin in an experimental model of pulpal inflammatory in mice

AIM

To evaluate whether treatment with resiniferatoxin (RTX) is capable of lowering the plasma levels of PGE₂ and TNF-α, as well as histopathological parameters in inflammation of pulp tissue in a mouse experimental model.

METHODOLOGY

Ten groups of six BALB/c mice were formed as follows: healthy group (H_C ), healthy group treated with RTX (H_RTX ), two groups with pulp inflammation at 14 and 18 hours (PI₁₄ /PI₁₈ ), six groups with pulpal inflammation plus treatment with Ibuprofen (IBU₁₄ /IBU₁₈ ), dexamethasone (DEX₁₄ /DEX₁₈ ) and resiniferatoxin (RTX₁₄ /RTX₁₈ ) at 14 and 18 hours, respectively. Pulpal inflammation was induced through occlusal exposure of the pulp of the maxillary first molar. The plasma levels of PGE₂ and TNF-α and the histological parameters of the pulp tissue of the H_C and H_RTX groups were evaluated at the time of acquiring the animals. In the other groups, the plasma levels of PGE₂ and TNF-α and the histopathological parameters were evaluated at 14 and 18 hours after pulp damage. Plasma levels of PGE₂ and TNF-α were quantified by ELISA, and the histopathological parameters were evaluated by H/E staining. Statistical significance was determined by one-way analysis of variance (ANOVA) to test for overall differences between group means.

RESULTS

A significant increase (*p < .05) in plasma levels of PGE₂ and TNF-α occurred 14 and 18 hours after pulp damage. In addition, treatment with RTX significantly decreased (*p < .05) the plasma levels of PGE₂ and TNF-α at 14 and 18 hours after pulp damage, as well as the infiltrate of inflammatory cells at 18 hours after pulp damage, similarly to treatment with ibuprofen and dexamethasone.

CONCLUSION

It was possible to detect systemic levels of PGE₂ and TNF-α at 14 and 18 hours after pulp damage. Likewise, treatment with RTX was associated with an anti-inflammatory effect similar to treatment with ibuprofen and dexamethasone. These findings place resiniferatoxin as a therapeutic alternative in the treatment of inflammatory diseases in Dentistry.

Multifaceted effect of caffeic acid against Streptococcus mutans infection: microbicidal and immunomodulatory agent in macrophages

The aim of the present study was to investigate the effects of caffeic acid in the interface between the antimicrobial and anti-inflammatory function in macrophage response against S. mutans. S. mutans (10⁸ cfu/mL) were incubated with caffeic acid to determinate the half-maximal inhibitory concentration (IC₅₀) and macrophage cells were incubated with caffeic acid to determinate cell viability and toxicity. Anti-inflammatory effects were measured by nitrite accumulation, TNF-α and PGE₂ production, and NF-kB phosphorylation, and S. mutans survival following internalization by macrophages was investigated. We found that caffeic acid presented antimicrobial activity against S. mutans (IC₅₀ = 2.938 ± 0.1225 mM) without exerting cytotoxicity. Caffeic acid inhibited nitrite, TNF-α and PGE₂ production by the NF-kB dependent pathway, indicating an immunomodulatory property. Caffeic acid also contributed to macrophage bacteria clearance activity. In summary, caffeic acid presented antimicrobial activity against S. mutans and anti-inflammatory effects in macrophages.

Association between concentration of active MMP-9 in pulpal blood and pulpotomy outcome in permanent mature teeth with irreversible pulpitis - a preliminary study

AIM

To investigate the correlation between the concentration of active-matrix metalloproteinases-9 (aMMP-9) in pulpal blood and the outcome of pulpotomy in mature permanent teeth with symptomatic irreversible pulpitis (SIP).

METHODOLOGY

Forty permanent molar teeth with a clinical diagnosis of SIP and normal apical tissues with periapical index (PAI) score ≤ 2 and ten permanent teeth (8 molars and two premolars) with a diagnosis of normal pulp that required root canal treatment for prosthetic reasons from patients between the ages of 15-35 years were recruited. All clinical procedures were performed under local anaesthesia and rubber dam isolation. After access opening, the coronal pulp tissue was amputated up to the canal orifice. A 100 μL volume of the pulpal blood was collected using a micropipette and transported to the laboratory. Sodium hypochlorite (2.5 %) was used as a haemostatic agent, and mineral trioxide aggregate (MTA) was used as the pulp capping material. The tooth was restored with composite at the same visit. Teeth with normal pulps were treated with single-visit root canal treatment. Patients with pulpotomy were recalled at 6 and 12 months. Outcome assessment of teeth with pulpotomy was carried out at 12 months and was categorized as success (asymptomatic patients with PAI score ≤ 2) or failure (symptomatic patients or PAI score ≥ 3). Quantification of aMMP-9 in pulpal blood was achieved using a fluorometric assay. The following statistical analyses were performed to assess the data: t-test, Fisher's exact test, kappa coefficient, non-parametric test, Wilcoxon rank-sum test, Spearman rank correlation test and receiver operating characteristic curve (ROC).

RESULT

The success rate of pulpotomy was 88 % at 12-months. There was a significant difference between the median concentrations of aMMP-9 in pulpal blood of teeth with normal pulps (52 (12-96) ng mL^-1 :) and SIP (193.3 (25.8-607.7) ng mL^-1 :) (P = 0.0003) and successful (132.3 (25.8-548.3) ng mL^-1 :) and failed cases (512.4 (334.8-607.7 ng mL^-1 :) (P = 0.0015) of MTA pulpotomy. A significant association was established between aMMP-9 concentration and outcome of pulpotomy. The area under the receiver operating characteristics curve (0.9484, 95%CI) suggested excellent discriminatory power of aMMP-9 concentration in pulpal blood to predict the pulpotomy outcome.

CONCLUSION

The pulpal blood concentration of aMMP-9 was significantly associated with the outcome of pulpotomy in teeth with symptomatic irreversible pulpitis, where it may be used as a potential prognostic biomarker.

The effect of topical application of meloxicam on inflamed dental pulp

Background/purpose

Effective regulation of the inflammatory process is essential for pulp repair and regeneration. Meloxicam has anti-inflammatory activity in systemic administration. The purpose of this study is to observe effects of topically applied meloxicam on inflamed pulp and to explore its potential value in the treatment of pulpitis.

Materials and methods

The coronal pulp tissues of rat molars were stimulated with 10 mg/mL lipopolysaccharide (LPS group) and then treated with 500 μmol/L meloxicam (meloxicam group). The untreated pulp tissues were used as the control group. After 3 h of incubation in vitro, the gene expression of interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) in each group was detected by real-time RT-PCR. The pulp tissues of each group were randomly subcutaneously implanted into nude mice, and 500 μmol/L meloxicam was injected into the subcutaneous pocket of the meloxicam group. Haematoxylin eosin staining, Masson staining and immunohistochemical staining were performed on samples after 3 days and 4 weeks retrieval, respectively.

Results

Compared with the LPS group, the mRNA expression levels of TNF-α and IL-6 of the meloxicam group were significantly reduced in vitro. The inflammatory response and cyclooxygenase-2 expression of the meloxicam group were decreased, and osteodentin-like tissue was generated in the pulp cross section of the meloxicam group in vivo.

Conclusion

The topical application of meloxicam inhibits the inflammatory response of inflamed pulp and further promotes the formation of osteodentin-like tissues but fails to induce the formation of the pulp–dentin complex. Topically applied meloxicam has the potential to regulate pulp inflammation.

Comparison of Neurokinin A, Substance P, Interleukin 8, and Matrix Metalloproteinase-8 Changes in Pulp tissue and Gingival Crevicular Fluid Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth

INTRODUTION

The aim of this study was to compare levels of neurokinin A (NKA), substance P (SP), interleukin (IL)-8, and matrix metalloproteinase-8 (MMP-8) in pulp tissue and gingival crevicular fluid (GCF) samples of healthy and symptomatic irreversible pulpitis teeth.

METHODS

Forty patients diagnosed with healthy and symptomatic irreversible pulpitis teeth were included in this study. NKA, SP, IL-8, and MMP-8 levels were measured using the enzyme-linked immunosorbent assay test after pulp and GCF samples were obtained from healthy (n = 20) and symptomatic irreversible pulpitis teeth (n = 20). GCF sampling of 40 teeth was repeated 1 week later. Routine root canal treatment procedures of the teeth were performed, and the treatment process was completed. As a control group, GCF samples were taken from the contralateral teeth in both groups. Statistical analysis was performed using dependent and independent t tests, analysis of variance, Kruskal-Wallis, Mann-Whitney U tests, and Pearson correlation analysis.

RESULTS

Comparing the groups, all mediator levels were significantly higher in the pulp samples in the pulpitis group compared with the healthy group (NKA: P < .001, SP: P = .005, IL-8: P < .001, and MMP-8: P < .001). Likewise, in the pulpitis group, all mediator levels were significantly higher in the first GCF samples compared with the healthy group (NKA: P = .01, SP: P < .001, IL-8: P = .001, and MMP-8: P < .001).

CONCLUSIONS

It was observed that NKA, SP, IL-8, and MMP-8 increased significantly in pulp tissue and GCF specimens of symptomatic irreversible pulpitis teeth compared with pulp tissue and GCF specimens of healthy teeth. Second, it was determined that NKA, SP, IL-8, and MMP-8 levels decreased significantly in GCF samples in teeth diagnosed with symptomatic irreversible pulpitis 1 week after the removal of inflamed pulp. Finally, SP, IL-8, and MMP-8 levels were found to be higher in pulp tissue samples of the patients with symptomatic irreversible pulpitis with higher pain scores than those with low pain scores.

Metalloproteinase 14 (MMP-14) and hsa-miR-410-3p expression in human inflamed dental pulp and odontoblasts

The objective of this study is to evaluate MMP-14 expression in odontoblasts and in the bulk of dental pulp of teeth with pulpitis; to determine the expression of microRNA-410 (miR-410) in pulp tissue, since sequence analysis suggests that miR-410 has potential binding site on MMP-14’s 3′UTR, and hence, can regulate expression of the latter one. Tissue samples of dental pulp from teeth with pulpitis and healthy (control) were formalin fixed and paraffin embedded (FFPE). Samples were examined using immunohistochemical staining for MMP-14 and the expression of miR-410 was evaluated using qRT-PCR. In both, healthy and inflamed pulp odontoblasts stained more intensively than remaining pulp tissue, but this difference was not statistically significant. More positive staining was observed in inflamed pulps compared to healthy pulps. Expression of miR-410 was found significantly lower in inflamed pulps than in healthy ones. In the two examined zones, odontoblasts and remaining pulp, miR-410 was expressed on a similar level. No statistically significant correlation of miR-410 and MMP-14 expression was found. We showed that inflammation changes the MMP-14 expression in pulp tissue and odontoblasts. This study demonstrates for the first time miR-410 expression in human dental pulp and that expression of this microRNA was downregulated in inflamed dental pulp and odontoblasts.

Decreased expression of microRNA-30b promotes the development of pulpitis by upregulating the expression of interleukin-6 receptor

The present study aimed to examine the expression of interleukin-6 receptor (IL-6R) mRNA and protein in pulp tissues, blood and saliva from patients with pulpitis. It also investigated the association between IL-6R and microRNA (miR)-30b, as well as their effects on pulpitis. A total of 28 patients with pulpitis were recruited into the experimental group and 16 subjects with no pulpitis who also underwent tooth extraction were recruited into the control group. Pulp tissues, plasma and saliva were collected from all participants. Reverse transcription-quantitative polymerase chain reaction was used to determine the expression of IL-6R mRNA and miR-30b in all sample types. Western blot analysis was performed to examine the protein expression of IL-6R in pulp tissues, while ELISA was used to determine the contents of IL-6R protein in the plasma and saliva samples. A dual luciferase reporter assay was performed to verify the interactions between IL-6R and miR-30b. The expression of IL-6R mRNA in the pulp tissues, plasma and saliva was significantly increased in patients with pulpitis compared with the control group. Similarly, the IL-6R protein expression in the samples from patients with pulpitis were also significantly increased compared with the control group. Conversely, the expression of miR-30b was significantly reduced in the samples from patients with pulpitis compared with the control group. The dual luciferase reporter assay revealed that miR-30b may bind with the 3'-untranslated seed region of IL-6R mRNA to regulate its expression. The present study demonstrated that the upregulated expression of IL-6R in pulp tissues, plasma and saliva from patients with pulpitis was associated with the downregulation of miR-30b expression. In addition, miR-30b may affect the progression of pulpitis via IL-6R and may be a potential genetic marker for the diagnosis of pulpitis.

Inflammatory cytokines in normal and irreversibly inflamed pulps: A systematic review

OBJECTIVE

To review the available literature in regard to the inflammatory process and pulpitis. Setting forth to evaluate if differences in the levels of various cytokines (TNF-α, IL-1β, IL-2, IL-6 and IL-8) can be observed in clinically diagnosed normal and irreversibly inflamed pulps that could serve as possible markers and/or diagnostic tools to predict and differentiate between certain states of inflammation. Methods used to measure and assess levels of cytokines have been limited to two protein quantification methods ELISA and/or Multiplex Array.

DESIGN

The databases PubMed, EMBASE/Ovid, The Cochrane Central Register of Controlled Trials, Cochrane Reviews and Scopus were consulted for the electronic literature search. Screening of titles and abstracts followed the PRISMA guidelines while data extraction and the assessment of the full texts were carried out in accordance to the GRADES assessment.

RESULTS

The review showed that significant increases in levels of IL-1β, IL-2, IL-6, IL-8 and TNF-α in irreversible pulpitis samples exist, in comparison to normal pulp samples which serve as a good basis for potential markers. Due to larger discrepancies in available literature, IL-2 seems rather unsuitable at the moment, while IL-6 and TNF alpha seem to be more promising.

CONCLUSION

It may be concluded that even by combining two protein quantification methods inconsistencies between studies exist. At the moment it is difficult to select just one specific cytokine suitable for testing, rather it supports the rationale that further high-quality clinical studies are needed.

Biological Markers for Pulpal Inflammation: A Systematic Review

Background and Objective

Pulpitis is mainly caused by an opportunistic infection of the pulp space with commensal oral microorganisms. Depending on the state of inflammation, different treatment regimes are currently advocated. Predictable vital pulp therapy depends on accurate determination of the pulpal status that will allow repair to occur. The role of several players of the host response in pulpitis is well documented: cytokines, proteases, inflammatory mediators, growth factors, antimicrobial peptides and others contribute to pulpal defense mechanisms; these factors may serve as biomarkers that indicate the status of the pulp. Therefore, the aim of this systematic review was to evaluate the presence of biomarkers in pulpitis.

Methods

The electronic databases of MEDLINE, EMBASE, Scopus and other sources were searched for English and non-English articles published through February 2015. Two independent reviewers extracted information regarding study design, tissue or analyte used, outcome measures, results and conclusions for each article. The quality of the included studies was assessed using a modification of the Newcastle-Ottawa-Scale.

Results and Conclusions

From the initial 847 publications evaluated, a total of 57 articles were included in this review. In general, irreversible pulpitis was associated with different expression of various biomarkers compared to normal controls. These biomarkers were significantly expressed not only in pulp tissue, but also in gingival crevicular fluid that can be collected non-invasively, and in dentin fluid that can be analyzed without extirpating the entire pulpal tissue. Such data may then be used to accurately differentiate diseased from healthy pulp tissue. The interplay of pulpal biomarkers and their potential use for a more accurate and biologically based diagnostic tool in endodontics is envisaged.

Catechins inhibit vascular endothelial growth factor production and cyclooxygenase-2 expression in human dental pulp cells

AIM

To investigate the effect of catechins on vascular endothelial growth factor (VEGF) production and cyclooxygenase-2 (COX-2) expression in human dental pulp cells (HDPC) stimulated with bacteria-derived factors or pro-inflammatory cytokines.

METHODOLOGY

Morphologically fibroblastic cells established from explant cultures of healthy human dental pulp tissues were used as HDPC. HDPC pre-treated with catechins, epigallocatechin-3-gallate (EGCG) or epicatechin gallate (ECG), were exposed to lipopolysaccharide (LPS), peptidoglycan (PG), interlukin-1β (IL-1β) or tumour necrosis factor-α (TNF-α). VEGF production was examined by enzyme-linked immunosorbent assay, and COX-2 expression was assessed by immunoblot.

RESULTS

EGCG and ECG significantly reduced LPS- or PG-mediated VEGF production in the HDPC in a dose-dependent manner. EGCG also prevented IL-1β-mediated VEGF production. Although TNF-α did not enhance VEGF production in the dental pulp cells, treatment of 20 μg mL(-1) of EGCG decreased the level of VEGF. In addition, the catechins attenuated COX-2 expression induced by LPS and IL-1β.

CONCLUSIONS

The up-regulated VEGF and COX-2 expressions in the HDPC stimulated with these bacteria-derived factors or IL-1β were diminished by the treatment of EGCG and ECG. These findings suggest that the catechins may be beneficial as an anti-inflammatory tool of the treatment for pulpal inflammation.

NOD2 Mediates Odontoblast Differentiation and RANKL Expression

The precise regulation of odontoblast differentiation and osteoclastogenic cytokine expression in human dental pulp cells (HDPCs) is crucial for the pathology of bacteria-related pulpitis. Although the up-regulation of nucleotide-binding oligomerization domain-containing protein 2 (NOD2) has been reported in inflamed human dental pulps, the role of NOD2 in the differentiation of HDPCs remains unclear. Here, we show the involvement of NOD2 in odontoblast differentiation together with osteoclastogenic cytokine expression in HDPCs. Treatment with muramyl dipeptide (MDP), a known NOD2-agonist, significantly inhibited odontoblast differentiation of HDPCs, as revealed by reduced ALP activity, osteoblast/odontoblast marker expression, and mineralized nodule formation. Importantly, the forced down-regulation of NOD2 by small interfering RNA (siRNA) recovered MDP-down-regulated odontoblast differentiation. MDP-elicited suppression of odontoblast differentiation resulted from the increased expression of MKP-1 protein and the subsequent decline of MAPKs phosphorylation, which is a prerequisite for odontoblast differentiation. Furthermore, we found that MDP treatment elevated the expression of osteoclastogenic cytokines in HDPCs, which was also reversed by NOD2 silencing. Analysis of these data, taken together, suggests that the regulation of NOD2 expression upon MDP challenge might serve as an intrinsic mechanism that underlies the hindered dentin formation and accelerated dentin resorption in bacterial infection-mediated pulpitis.

Prostaglandin E2 to diagnose between reversible and irreversible pulpitis

The aim of this work is to verify a correlation between the grade of inflammation and the concentration of PGE2 in human dental pulp. A total of 25 human dental pulps were examined by histological analysis and radioimmunologic dosage of PGE2. The pulps used in this experiment were from healthy and symptomatic teeth; the first ones were collected from teeth destined to be extracted for orthodontic reasons. An increase was observed of PGE2 in reversible pulpitis compared with healthy pulps and with the irreversible pulpitis and the clear decrease of these when NSAIDs are taken. This study demonstrates that PGE2 level is correlated to histological analysis thus allowing to distinguish symptomatic teeth in reversible and irreversible pulpitis.

Gene expression analysis of membrane transport proteins in normal and lipopolysaccharide-inflamed rat dental pulp

INTRODUCTION

Membrane transport proteins (transporters) play a crucial role in the transmembrane uptake and/or efflux of various compounds such as inorganic ions, endogenous bioactive substances such as prostaglandins (PGs), and drugs such as nonsteroidal anti-inflammatory drugs. This study aimed to analyze mRNA expression of selected transporters related to drug disposition and PG transport in normal and lipopolysaccharide (LPS)-inflamed rat incisor pulp.

METHODS

Pulp tissues were subjected to reverse transcription-polymerase chain reaction (PCR) detection for transporter isoforms belonging to organic anion transporting polypeptide (Oatp), organic anion transporter (Oat), organic cation transporter (Oct), multidrug resistance-associated protein (Mrp), and multidrug resistance protein (Mdr) families. The levels of mRNA expression for PG transporters (Oatp1a5, Oatp1b2, Oatp2a1, Oatp2b1, and Oatp3a1) were compared in normal and LPS-inflamed pulps by using real-time PCR.

RESULTS

The pulp tissue expressed mRNAs for various transporters belonging to the Oatp, Oat, Oct, Mrp, and Mdr families. LPS inflammation caused significant up-regulation of Oatp2a1 (P < .01) and significant down-regulation of Oatp1a5, Oatp2b1 (P < .01), and Oatp3a1 (P < .05).

CONCLUSIONS

Rat incisor dental pulp expressed mRNAs for various transporter isoforms. The levels of mRNA expression for PG transporters were significantly up-regulated or down-regulated in LPS-inflamed dental pulp.

The relationship of pulp polyp with the presence and concentration of immunoglobulin E, histamine, interleukin-4 and interleukin-12

The aim of this study was to evaluate the relationship between pulp polyp formation and immunoglobulin E (IgE), histamine and interleukin-4 (IL-4) as the most important mediators which are involved in allergy. Thirty-two samples including 16 pulp polyps and 16 normal pulps were gathered. After homogenising the pulpal tissue samples, enzyme-linked immunosorbent assay (ELISA) techniques were used to assess the concentration of IgE, histamine, IL-4 and IL-12. The two groups showed statistically significant differences in terms of both the concentration and presence of IgE, histamine and IL-4 (P < 0.001); both presence and concentration of IgE, histamine and IL-4 were higher in pulp polyps than in normal pulps. There is not any significant difference between case and control groups regarding IL-12. The results of this study give rise to the possibility of type I hypersensitivity reaction being involved in pulp polyp's pathogenesis.

Roles of TLR2, TLR4, NOD2, and NOD1 in Pulp Fibroblasts

Pulp fibroblasts express various pro-inflammatory mediators leading to marked infiltration of inflammatory cells in the progression of pulpitis. We hypothesized that pulp fibroblasts play roles in the recognition of invaded caries-related bacteria and the subsequent innate immune responses. We found clear expressions of TLR2, NOD1, and NOD2 and a faint expression of TLR4 in human dental pulp fibroblasts (HDPF) by RT-PCR and flow cytometry. We also observed that various pro-inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostaglandin E2 and its key enzyme COX-2, not iNOS or caspase-1, were markedly up-regulated by stimulation with these TLR and NOD agonists. More over, the NOD2 agonist acted synergistically with the TLR2, not the TLR4, agonist to stimulate the production of pro-inflammatory mediators in HDPF. These findings indicate that TLR2, TLR4, NOD2, and NOD1 in HDPF are functional receptors, and NOD2 is a modulator of signals transmitted through TLR2 in pulpal immune responses, leading to progressive pulpitis.

Direct pulp capping with mineral trioxide aggregate: an observational study

BACKGROUND

Pulp capping in carious teeth has been considered unpredictable and therefore contraindicated. A recently developed material, mineral trioxide aggregate (MTA), resists bacterial leakage and may provide protection for the pulp, allowing repair and continued pulp vitality in teeth when used in combination with a sealed restoration.

METHODS

Forty patients aged 7 to 45 years accepted pulp-capping treatment when they received a diagnosis no more severe than reversible pulpitis after undergoing cold testing and radiographic examination. The primary author removed caries using a caries detector dye and sodium hypochlorite solution for hemostasis and placed MTA over the exposures and all surrounding dentin. The operator then restored the teeth provisionally with unbonded Clearfil Photocore (Kuraray Medical, Okayama, Japan). During a second visit, the operator restored the teeth with bonded composite after sensibility testing and confirmed MTA curing. At recall appointments, patients were evaluated for reparative dentin formation, pulpal calcification, continued normal root development and evidence of pathosis.

RESULTS

Over an observation period of nine years, the authors followed 49 of 53 teeth and found that 97.96 percent had favorable outcomes on the basis of radiographic appearance, subjective symptoms and cold testing. All teeth in younger patients (15/15) that initially had open apexes showed completed root formation (apexogenesis).

CONCLUSIONS

MTA can be a reliable pulp-capping material on direct carious exposures in permanent teeth when a two-visit treatment protocol is observed.

PRACTICE IMPLICATIONS

Vital pulp therapy using MTA is a treatment option for teeth diagnosed with a condition no more severe than reversible pulpitis.

Expression of Macrophage Inflammatory Protein 3α in Human Inflamed Dental Pulp Tissue

Severe pulpitis resulting from dental caries is characterized by marked inflammatory infiltrate such as lymphocytes. Little is known about the recruitment of these cells into the dental pulp lesions of carious teeth. Macrophage inflammatory protein-3alpha (MIP-3alpha), a CC chemokine attracts CC chemokine receptor 6 (CCR6)-expressing T cells. We examined the distribution of MIP-3alpha-positive and/or CCR6-positive cells in human inflamed and normal dental pulp by immunohistochemistry. MIP-3alpha was observed in all inflamed pulp sections, and was mostly distributed in macrophages that had accumulated in the area adjacent to carious lesions. Furthermore, CCR6 expression was also observed in the infiltrating lymphocytes. In contrast, MIP-3alpha and CCR6 were rarely detected in normal pulp. These findings suggest that MIP-3alpha plays a role in the advancement of pulpal inflammation via the recruitment of CCR6-expressing lymphocytes.

Hepatocyte growth factor/scatter factor in development, inflammation and carcinogenesis: its expression and role in oral tissues

Hepatocyte growth factor (HGF) was discovered as a potent mitogen for adult hepatocytes from the plasma of patients with fulminant hepatic failure. It is now known to be a broad-spectrum, multi-functional mitogen, motogen and morphogen. The activities of HGF are mediated through the signalling pathway of its receptor, c-Met. During tooth development, HGF is expressed in the dental papilla and c-Met is expressed in the inner enamel epithelium. The expression of HGF and c-Met indicates that HGF is involved in morphogenesis of the tooth by mediating epithelial-mesenchymal interactions. In the mature tooth, HGF expression by fibroblasts is enhanced in pulpitis and mediated through the induction of prostaglandin (PG) E(2); it is induced not only by inflammatory cytokines, but also by components of oral bacteria. Consequently, concentrations of HGF in gingival crevicular fluid (GCF) increase in periodontitis. The mitogenic and other biological activities, such as angiogenesis, of HGF contribute towards wound healing. Both HGF and c-Met are expressed in the developing tongue, and the signalling pathway of the latter is shown to be essential for myogenesis. Dysregulation of c-Met signalling is observed in carcinogenesis, but HGF also has cytotoxic activity to certain tumour cells. The reason for the discrepancy between these observations is not clear at present.

Pulp biology: progress during the past 25 years

During the past 25 years there has been a rapid expansion in our knowledge of the dentine and pulp complex. This paper provides representative examples of important advances that researchers have made in this field. Topics to be considered include: differentiation of odontoblasts, dentine matrix proteins, extent of odontoblast processes, pulpal stem cells, apoptosis, interstitial fluid pressure in normal and inflamed pulps, class II antigen-presenting cells of the pulp, cytokines, antibodies, pulpal calcifications, tertiary dentine and pulpal inflammation associated with bacterial contamination of exposed dentine beneath restorations.

Effect of an intraosseous injection of depo-medrol on pulpal concentrations of PGE2 and IL-8 in untreated irreversible pulpitis

The purpose of this prospective, randomized, double-blind study was to evaluate the pulpal concentrations of prostaglandin E2 (PGE2) and interleukin-8 (IL-8) in untreated teeth with irreversible pulpitis after the administration of an intraosseous injection of Depo-Medrol. Forty emergency patients with a clinical diagnosis of irreversible pulpitis experiencing moderate to severe pain participated. After receiving local anesthesia, patients randomly received, in a double-blind manner, an intraosseous injection of either 1 ml of Depo-Medrol (40 mg) (20 patients) or 1 ml of sterile saline placebo (control) (20 patients). No endodontic treatment was initiated. At 1 or 3 days after the intraosseous injection, the teeth were extracted and the pulpal tissue harvested. Prostaglandin E2 and interleukin-8 concentrations were determined by enzyme immunoassay. Results demonstrated a significantly (p < 0.05) lower concentration of prostaglandin E2 compared to the saline group at day 1. There were no significant (p > 0.05) differences between the two groups at day 3. The pulpal concentrations of prostaglandin E2 were reduced at 1 day after the intraosseous injection of Depo-Medrol.

Prostaglandin E2 and treatment outcome in pulp therapy of primary molars with carious exposures

OBJECTIVES

Prostaglandin E2 (PGE2) has been suggested as an indicator of irreversible pulpitis in permanent teeth [1]. There is scant information on the role of chemical mediators in primary molar pulp inflammation. The aim of this preliminary study was to investigate the levels of PGE2 in blood harvested from root pulp stumps following coronal pulp amputation in vital primary molar teeth with carious exposures.

METHODS

Seventy-nine cariously exposed primary molars underwent treatment by one of two vital pulp therapy techniques. Blood was harvested from 38 teeth and volume and concentration of PGE2 ([PGE2]) determined [2]. Treatment outcome was assessed from both clinical and radiographic evidence.

RESULTS

PGE2 was detected in all samples, with a wide concentration range (1-2641 ng/mL). The distribution was skewed, requiring log transformation. The difference in the mean (log) [PGE2] for radiological success (3.12, SD 1.60 and failure (4.62, SD 1.80) was significant, t = 2.05, P = 0.047. The difference in the mean (log) [PGE2] for clinical success (3.24, SD 1.65) and failure (5.44, SD 1.43 was near-significant, t = 1.84, P = 0.074.

CONCLUSION

[PGE2] correlated positively with radiological outcome following vital pulp therapy.

An immunohistological study on cyclooxygenase-2 in human dental pulp

Characteristics of cyclooxygenase-2 (COX-2) expressing cells in human dental pulp were immunohistologically studied. Extirpated pulpal tissues from extracted teeth were examined to elucidate the localization and distribution of COX-2. Pulpal tissues were examined by the labeled streptavidin biotin method using specific mouse monoclonal antibodies for COX-2. Cell types of the COX-2 expressing cells were also investigated by the double stain technique using both monoclonal antibodies for CD68/macrophage and anti-COX-2. COX-2 expressing cells could be found in all of the inflamed pulps, and these cells were mostly distributed close to the area of accumulation of inflammatory cells. COX-2 was mainly expressed in fibroblasts rather than macrophages. In contrast, COX-2 expressing cells were scarcely found in the normal pulps. These findings indicate that pulpal fibroblasts, as well as macrophages, may participate in the production of prostaglandin through COX-2 expression in pulpal inflammation, and might be involved in the pathogenesis of irreversible pulpitis.

Bradykinin levels in dental pulp by microdialysis

Bradykinin is a potent mediator of pain and inflammation. To examine extracellular levels of bradykinin in human dental pulp, CMA/20 microdialysis probes were inserted into the pulp tissue of 22 teeth diagnosed with normal pulp or with irreversible pulpitis before their extraction or endodontic therapy. Probes were perfused with a modified Locke-Ringer's buffer and bradykinin levels in the dialysate evaluated using a radioimmunoassay. Mean extracellular levels of bradykinin within pulp tissue diagnosed with irreversible pulpitis were significantly higher (262.26 +/- 83.79 fmol/ml) than that found within normal pulp (19.41 +/- 6.47 fmol/ml). Highest levels of bradykinin were detected in pulp tissue diagnosed with irreversible pulpitis when the patient had reported pain in the past, compared with patients who were in pain just before their visit. These observations suggest that the bradykinin system is activated during pulpitis and may contribute to pain and inflammation.

Cytokine induction by Streptococcus mutans and pulpal pathogenesis

Chronic pulpal inflammation under caries appears to be elicited by bacterial antigens that diffuse into the pulp through dentinal tubules. This prompted the hypothesis that cytokines elicited by antigens from Streptococcus mutans, which frequently dominates shallow lesions, could play a major role in eliciting the initial T-cell response in the pulp. To test this, we examined the ability of S. mutans to stimulate T cells and elicit cytokines and used Lactobacillus casei, which often predominates in deep carious lesions where B cells and plasma cells predominate, as a control. In addition, the presence of cytokines in the pulp was analyzed at the mRNA level. S. mutans elicited potent gamma interferon (IFN-gamma) responses in peripheral blood mononuclear cell cultures and reduced the CD4/CD8 ratio by promoting CD8(+) T cells. Multiple inflammatory cytokine mRNAs (IFN-gamma, interleukin 4 [IL-4], and IL-10) were detected in human dental pulp. A higher prevalence of IFN-gamma (67%) than IL-4 (19%) or IL-10 (29%) was obtained in shallow caries, suggesting a type 1 cytokine mechanism in early pulpitis where S. mutans predominates. In contrast, in deep caries no differences in cytokine frequency were observed. Furthermore, the presence of IFN-gamma in the pulp correlated with the presence of S. mutans. The extraordinary induction of type 1 cytokines and the preferential activation of CD8(+) T cells by S. mutans offers an explanation for the etiology of the CD8(+) T-cell-dominant lesion in early pulpitis and suggests that S. mutans may have a major impact on the initial lesion and pulpal pathology.

Prostaglandin E2 predominantly induces production of hepatocyte growth factor/scatter factor in human dental pulp in acute inflammation

Hepatocyte growth factor (HGF), which is also known as the scatter factor, is a broad-spectrum and multifunctional cytokine, mediates epithelial-mesenchyme interaction, and is shown to be involved in the development and regeneration of various tissues, including tooth. Here, we report that HGF was present in adult human dental pulps, and its levels increased during acute inflammation of the tissue. Levels of HGF mRNA in dental pulps also increased with inflammation, as determined by reverse-transcription/polymerase chain-reaction. The production of HGF in fibroblasts from dental pulps in culture was dose-dependently stimulated by inflammatory cytokines such as interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha, and by prostaglandin (PG) E2, as determined by an enzyme-linked immunosorbent assay. We also showed that indomethacin did not affect the increase in HGF production by the cells with IL-1alpha, TNF-alpha, and PGE2. The levels of HGF mRNA in the cells were simultaneously increased by these stimulants, as determined by Northern blotting. Since the production of PGs is known to increase at the beginning of inflammation, PGE2 may be involved in the regeneration of dental pulps by the induction of HGF expression after inflammation.