ILs and MMPs Levels in Inflamed Human Dental Pulp: A Systematic Review

Assessment of 10-MDP and GPDM monomers on viability and inflammatory response in human dental pulp stem cells

OBJECTIVES

to assess the cytotoxicity of the following functional monomers used in dental adhesives: 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) and glycerol phosphate dimethacrylate (GPDM), and their effect on cytokine release from human dental pulp stem cells (hDPSCs).

METHODS

The hDPSCs cells were isolated from the dental pulp of extracted human third molars. The functional monomers, 10-MDP and GPDM, were diluted in dimethyl sulfoxide (DMSO) at concentrations ranging from 1 to 4 mM. Cells not exposed to the compounds served as controls. The hDPSCs were seeded into 96-well plates and incubated for 48 h. Subsequently, the cells were exposed to 10-MDP and GPDM for 24 h. Then, the culture medium was removed, the mitochondrial metabolism was evaluated using the MTT assay, while cell death analyzed by flow cytometry. Cytokine release (IL-1β, IL-6, IL-8, IL-10, TNF-α) was analyzed by the MAGPIX. The data were analyzed using one-way ANOVA and Tukey's test.

RESULTS

10-MDP demonstrated significant toxicity to hDPSCs, reaching the IC50 at 3 mM. However, its impact on cytokine release was minimal, resulting only in IL-6 and IL-8 levels. GPDM exhibited lower toxicity, even at 4 mM, but induced an increase in IL-1β release and a reduction in IL-6, IL-8, and IL-10 levels, with no effect on TNF-α. Despite the MTT assay results indicating cytotoxicity, the cell death was low for both functional monomers.

SIGNIFICANCE

10-MDP exhibited significant toxicity to hDPSCs, unlike GPDM, however, both monomers resulted in minimal cell death. 10-MDP had a minor impact on cytokine release, whereas GPDM demonstrated a potential to trigger an inflammatory reaction, particularly in the short term.

Role of Metalloproteinases in Adhesion to Radicular Dentin: A Literature Review

INTRODUCTION

Root dentin is a porous and complex dental surface that may have irregularities and deposits of organic material. To achieve an effective bond between restorative materials and root dentin, it is necessary that the restorative materials adhere intimately to the dentin surface. Metalloproteinases (MMPs) are a group of proteolytic enzymes that perform an important role in degrading the extracellular matrix and remodeling connective tissue. The aim of this research was to determine the scientific evidence available on the role played by MMPs in adhesion to root dentin and their putative inhibitors.

MATERIALS AND METHODS

Several techniques have been used to evaluate the presence of MMPs in the root dentin of human and bovine teeth, such as Western blot, immunohistochemistry, immunofluorescence, and zymography, the latter also being used together with the EnzCheck assay to evaluate the inhibitory effect of adhesion protocols on the activity of root MMPs in vitro.

RESULTS

When analyzing the databases, 236 articles were found, 12 of which met the selection criteria. The variables analyzed were articles that evaluated different MMP inhibitors in root dentin.

CONCLUSIONS

In the adhesion to radicular dentin, MMPs have a crucial role in the degradation of the extracellular matrix of dentin and the remodeling of the dentin surface because excessive MMP activity can be harmful to dental health, since excessive degradation of the extracellular matrix of dentin can weaken the tooth structure and decrease fracture resistance. Therefore, it is important to monitor MMP activity during root dentin bonding procedures.

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.

Efficacy and inflammatory responses of root canal therapy plus periodontal non-surgical treatment for periodontal-endodontic combined dental lesions

OBJECTIVE

To investigate the efficacy and inflammatory responses of treating periodontal-endodontic combined lesions (PECLs) with root canal therapy (RCT) alone versus RCT combined with periodontal non-surgical treatment (PNST).

METHODS

A total of 103 patients with PECLs admitted between January 2019 and January 2020 to Shenzhen Baoan Women's and Children's Hospital were divided into control (RCT alone, 50 cases) and combined (RCT + PNST, 53 cases) groups. Comparative analyses included efficacy assessment, probing depth (PD), bleeding index (BI), plaque index (PLI), gingival index (GI), serum levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and high-sensitivity C-reactive protein (hs-CRP), pain severity during RCT, incidence of adverse reactions, post-treatment tooth conditions, and recurrence rates at 6 and 12 months. Univariate analysis identified factors associated with poor treatment outcome in PECL patients.

RESULTS

The combined group demonstrated a higher total effective rate (90.57%) compared to the control group (74.00%) (P < 0.05). Patients receiving combined therapy showed significantly lower PD, BI, PLI, GI, IL-1β, TNF-α, and hs-CRP levels, as well as reduced pain severity and lower recurrence rates at 6 and 12 months (all P < 0.05). The combined group also had a lower incidence of adverse (periodontal distending pain and local foreign body sensation) reactions (7.54%) compared to the control group (26.00%) (P < 0.05). After treatment, the incidence of periodontitis, percussion tenderness, and loosening of teeth in the combined group was lower than that of the control group, and the retention rate of affected teeth was significantly higher (all P < 0.05). Factors such as history of alcoholism, betel nut chewing, and treatment method (RCT) were significantly associated with poorer prognosis in PECL patients (P < 0.05).

CONCLUSION

Combined RCT and PNST improves clinical efficacy, reduces pain severity and inflammation levels, decreases adverse reactions, and enhances tooth retention in PECL patients. This treatment approach should be considered the preferred option for managing PECLs.

Revolutionizing the diagnosis of irreversible pulpitis - Current strategies and future directions

BACKGROUND

Pulpitis primarily arises from the pulp space infection by oral microbiota. Vital pulp therapy is a minimally invasive approach that relies on assessing the severity of pulpal inflammation to facilitate repair. However, the current evaluation methods prescribed by the American Association of Endodontics are subjective, leading to ambiguity in assessment. Therefore, this review aims to explore molecular strategies for evaluating the severity of pulpal inflammation to accurately predict the success of pulp vitality preservation in clinical settings.

METHODOLOGY

This review was conducted by searching relevant keywords, such as irreversible pulpitis, pulpitis biomarkers, molecular diagnosis, inflammation, and genomic strategies, in databases such as PubMed, Web of Science, and Scopus to address the subjective nature of diagnosis. The data included in this review were collected up to April 2023. The literature search revealed well-documented limitations in clinically assessing the pulp inflammatory. Molecular approaches that aid in clinical differentiation between irreversible and reversible pulpitis may potentially enhance favorable outcomes in vital pulp therapy. Non-invasive diagnostic methods for pulpal assessment would also be valuable for determining whether the inflamed pulp is reversible, irreversible, or necrotic.

CONCLUSION

The present review examines the various molecular diagnostic approaches that have revolutionized the medical field and are considered the most promising empirical methodologies for the proactive detection of pulpal diseases. It also provides comprehensive insights into the current diagnostic methods, associated challenges, next-generation strategies, and future directions for diagnosing the severity of pulp inflammation.

Data-driven dentistry: Computational revelations redefining pulp capping

Introduction

Pulpal and periradicular diseases stem from immune reactions to microbiota, causing inflammation. Limited blood supply hampers dental pulp self-healing. Managing inflammation involves eliminating bacteria and reducing pro-inflammatory mediators especially MMP-9, which has a significant correlation with pulpitis. s. Flavonoids like Hesperidin, Baicalein, Epigallocatechin gallate, Genistein, Icariin, and Quercetin show potential for pulp capping.

Aim

This in-silico study compares various Flavonoids for their anti-inflammatory effects on MMP-9, with Chlorhexidine as a control, a known MMP-9 inhibitor.

Materials and Methods

Protein and Ligand Preparation: The human MMP-9 catalytic domain (PDB ID: 4XCT) structure was retrieved, and necessary modifications were made. Flavonoids from PubChem database were prepared for docking using AutoDock Vina. A grid for docking was created, and molecular dynamics simulations were conducted using Gromacs-2019.4 with GROMOS96 force field. Trajectory analysis was performed, and MM-PBSA calculation determined binding free energies.

Results

Analysis of MMP-9 and ligand interactions revealed Hesperidin's high binding affinity, forming numerous hydrogen bonds with specific amino acids. Molecular dynamics simulations confirmed stability, with RMSD, RMSF, Rg, and SASA indicating consistent complex behaviour over 100 ns. MM-PBSA calculation affirmed favourable energy contributions in MMP-9-Hesperidin interactions.

Conclusion

MMP-9 plays a crucial role in prognosis of pulpitis. Incorporating MMP-9 inhibitors into pulp capping agents may enhance therapeutic efficacy. Hesperidin emerges as a potent MMP-9 inhibitor, warranting further in vivo validation against other agents.

Toxicity and cytokine release from human dental pulp stem cells after exposure to universal dental adhesives cured by single peak and polywave LEDs

OBJECTIVES

to assess the impact of universal adhesives, cured with single-peak and polywave LEDs, on the metabolic activity and cytokine release of human dental pulp stem cells (hDPSCs). In addition, analyze the degree of conversion (DC) of the adhesives cured with the different LEDs.

METHODS

Discs (5 mm diameter, 1 mm thick) were prepared using three universal adhesives: Single Bond Universal (SBU, 3 M ESPE), Optibond Universal (OBU, Kerr), and Zipbond Universal (ZBU, SDI). These discs were cured for 40 s using a single-peak (DeepCure, 3 M ESPE) or a polywave light-emmiting diode (LED) curing unit (Valo Grand, Ultradent). After 24 h, the specimens were placed in 24-well culture plates, each containing 1 mL of culture medium for 24 h. hDPSCs (1.8 ×104) were seeded in 96-well plates and allowed to grow for 24 h. Subsequently, the cells were exposed to the extracts (culture medium containing eluates from the adhesive discs) for an additional 24 h. Cells not exposed to the extracts were used as a control group. The mitochondrial metabolism was assessed using the MTT assay and the cytokine release evaluated through MAGPIX. The degree of conversion of the adhesives was analyzed using FTIR (n = 5). The results were analyzed by ANOVA two-way and Tukey's test.

RESULTS

OBU and ZBU eluates caused a statistically significant reduction in mitochondrial metabolism, regardless of the LED used, indicating their cytotoxicity. In contrast, SBU did not significantly affect the MTT results, resembling the control group. A higher release of cytokines IL-1, IL-6, IL-10, and TNF-α were found in association to ZBU. SBU, on the other hand, increased the release of IL-8. OBU did not influenced the cytokine release. SBU presented the higher DC, while OBU and ZBU had similar DC, lower than SBU.

SIGNIFICANCE

In conclusion, universal adhesives exhibit toxicity towards hDPSCs, but the extent of toxicity varies depending on the adhesive material. ZBU was associated with increased cytokine release, particularly pro-inflammatory mediators, from hDPSCs. The different LEDs did not influenced the cytotoxicity of the evaluated adhesives.

Matrix Metalloproteinases in the Periodontium-Vital in Tissue Turnover and Unfortunate in Periodontitis

The extracellular matrix (ECM) is a complex non-cellular three-dimensional macromolecular network present within all tissues and organs, forming the foundation on which cells sit, and composed of proteins (such as collagen), glycosaminoglycans, proteoglycans, minerals, and water. The ECM provides a fundamental framework for the cellular constituents of tissue and biochemical support to surrounding cells. The ECM is a highly dynamic structure that is constantly being remodeled. Matrix metalloproteinases (MMPs) are among the most important proteolytic enzymes of the ECM and are capable of degrading all ECM molecules. MMPs play a relevant role in physiological as well as pathological processes; MMPs participate in embryogenesis, morphogenesis, wound healing, and tissue remodeling, and therefore, their impaired activity may result in several problems. MMP activity is also associated with chronic inflammation, tissue breakdown, fibrosis, and cancer invasion and metastasis. The periodontium is a unique anatomical site, composed of a variety of connective tissues, created by the ECM. During periodontitis, a chronic inflammation affecting the periodontium, increased presence and activity of MMPs is observed, resulting in irreversible losses of periodontal tissues. MMP expression and activity may be controlled in various ways, one of which is the inhibition of their activity by an endogenous group of tissue inhibitors of metalloproteinases (TIMPs), as well as reversion-inducing cysteine-rich protein with Kazal motifs (RECK).

Dentin Degradation: From Tissue Breakdown to Possibilities for Therapeutic Intervention

Purpose of the Review

Presently, dental materials science is driven by the search for new and improved materials that can trigger specific reactions from the affected tissue to stimulate repair or regeneration while interacting with the oral environment to promote or maintain oral health. In parallel, evidence from the past decades has challenged the exclusive role of bacteria in dentin tissue degradation in caries, questioning our understanding of caries etiopathogenesis. The goal of this review is to recapitulate the current evidence on the host and bacterial contributions to degradation, inflammation, and repair of the dentin-pulp complex in caries.

Recent Findings

Contrasting findings attribute dentin breakdown to the activity of endogenous enzymes, such as matrix metalloproteinases (MMPs) and cathepsins, while the role of bacteria and their by-products in the destruction of dentin organic matrix and pulp inflammation has been for decades supported as an incontestable paradigm. Aiming to better understand the mechanisms involved in collagen degradation by host enzymes in caries, studies have showed that these proteinases are expressed in the mature dentin (i.e., after dentin formation) and become activated by the low pH in the acidic environment resulted by bacterial metabolism in caries. However, different host sources other than dentin-bound proteinases seem to also contribute to caries progression, such as saliva and pulp. Interestingly, studies evaluating pulp responses to bacteria invasion and inflammation in caries report higher levels of MMPs and cathepsins in inflamed tissue, but also showed MMP potential to resolve inflammation and stimulate wound healing. Notably, as reported for other tissues, MMPs exert dual roles in the dentin-pulp complex in caries, participating or regulating both degradative and reparative mechanisms.

Summary

The specific roles of host and bacteria and their by-products in caries progression have yet to be clarified. The complex interactions between inflammation and repair in caries pose challenges to a clear understanding of the dentin-pulp complex responses and changes to bacteria invasion. However, it opens new venues for the development of novel therapies and dental biomaterials based on the modulation of specific mechanisms to favor tissue repair and healing.

Co-initiators of polymerization can modulate the inflammatory cytokine release without major cytotoxic effects in human dental pulp cells

To evaluate the cytotoxicity of co-initiators of polymerization and its influence on cytokine release from human dental pulp cells (hDPCs). Cells were isolated from the dental pulp of sound human third molars. The co-initiators dimethylaminoethyl amine benzoate-(EDAB), 2-(dimethylamino)ethyl methacrylate (DMAEMA); 2-Ethylhexyl 4-(dimethylamino)benzoate (EHA) and bis(4-methyl phenyl)iodonium hexafluorophosphate (BPI) were diluted in dimethylsulfoxide (DMSO) at different concentrations. In this way, experimental groups and one control (without treatment) were obtained. hDPCs (10 × 10⁴ cell per well) were seeded on 96 well plates and incubated at 37°C and 5% CO₂ for 48 h. After this, the cells were exposed to different concentrations of co-initiators cited for 24 h. After this time, the culture medium was removed, and the mitochondrial metabolism was evaluated by MTT assay, cell death by flow cytometry, and cytokine released (IL-1β, IL6, IL-8, IL-10, and TNF-α) was analyzed by MAGPIX assay. The data were analyzed by ANOVA one-way and Tukey's test. EHA, DMAEMA, and EDAB did not reduce the mitochondrial metabolism. BPI presented high toxicity with remarkable reduction (80%) after exposure to 1 mM. The cell death of all test groups was similar to control. After 24 h treatment, the IL-8 was up-regulated by all compounds, while IL-6 was upregulated after exposure to EHA and downregulated after DMAEMA stimulation. BPI, EHA, EDAB, and DMAEMA can trigger an initial inflammatory response, upregulating the IL-8 secretion in hDPCs in a compound-concentration-dependent manner; however, this was not accompanied by major cytotoxic effects at cell death or mitochondrial-metabolism levels.

The Role of Cellular Metabolism in Maintaining the Function of the Dentine-Pulp Complex: A Narrative Review

The cellular metabolic processes ensure the physiological integrity of the dentine-pulp complex. Odontoblasts and odontoblast-like cells are responsible for the defence mechanisms in the form of tertiary dentine formation. In turn, the main defence reaction of the pulp is the development of inflammation, during which the metabolic and signalling pathways of the cells are significantly altered. The selected dental procedures, such as orthodontic treatment, resin infiltration, resin restorations or dental bleaching, can impact the cellular metabolism in the dental pulp. Among systemic metabolic diseases, diabetes mellitus causes the most consequences for the cellular metabolism of the dentine-pulp complex. Similarly, ageing processes present a proven effect on the metabolic functioning of the odontoblasts and the pulp cells. In the literature, several potential metabolic mediators demonstrating anti-inflammatory properties on inflamed dental pulp are mentioned. Moreover, the pulp stem cells exhibit the regenerative potential essential for maintaining the function of the dentine-pulp complex.