Stimulation phosphatidylinositol 3-kinase/protein kinase B signaling by Porphyromonas gingivalis lipopolysacch aride mediates interleukin-6 and interleukin-8 mRNA/protein expression in pulpal inflammation.

BACKGROUND/PURPOSE: The signaling mechanisms for Porphyromonas gingivalis lipopolysaccharide (PgLPS)-induced inflammation in human dental pulp cells are not fully clarified. This in vitro study aimed to evaluate the involvement of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in PgLPS-induced pulpal inflammation. METHODS: Human dental pulp cells (HDPCs) were challenged with PgLPS with or without pretreatment and coincubation with a PI3K/Akt inhibitor (LY294002). The gene or protein levels of PI3K, Akt, interleukin (IL)-6, IL-8, alkaline phosphatase (ALP), osteocalcin and osteonectin were analyzed by reverse transcription polymerase chain reaction (PCR), real-time PCR, western blotting, and immunofluorescent staining. In addition, an enzyme-linked immunosorbent assay was used to analyze IL-6 and IL-8 levels in culture medium. RESULTS: In response to 5 µg/ml PgLPS, IL-6, IL-8, and PI3K, but not Akt mRNA expression of HDPCs, was upregulated. IL-6, IL-8, PI3K, and p-Akt protein levels were stimulated by 10-50 µg/ml of PgLPS in HDPCs. PgLPS also induced IL-6 and IL-8 secretion at concentrations higher than 5 µg/ml. Pretreatment and co-incubation by LY294002 attenuated PgLPS-induced IL-6 and IL-8 mRNA expression in HDPCs. The mRNA expression of ALP, but not osteocalcin and osteonectin, was inhibited by higher concentrations of PgLPS in HDPCs. CONCLUSION: P. gingivalis contributes to pulpal inflammation in HDPCs by dysregulating PI3K/Akt signaling pathway to stimulate IL-6 and IL-8 mRNA/protein expression and secretion. These results are useful for understanding the pulpal inflammation and possible biomarkers of inflamed pulp diagnosis and treatment.

Overexpression of proinflammatory cytokines in dental pulp tissue and distinct bacterial microbiota in carious teeth of Mexican Individuals.

The prevalence of dental caries in the Mexican adult population aged 20 to 85 years is around 93.3%, and 50% in Mexican children and adolescents. Worldwide, it is the most common non-communicable disease. One of the main etiological factors for dental caries is the oral microbiome and changes in its structure and function, with an expansion of pathogenic bacteria like Streptococcus mutans. The exposed dental pulp tissue triggers an innate immune response to counteract this bacterial invasion. The relation between oral dysbiosis and innate immune responses remains unclear. We aimed to understand the relationship between innate immune response and the oral microbiota by quantifying the expression of Toll-like receptors (TLRs) and proinflammatory markers (cytokines and a chemokine) in dental pulp tissue, either exposed or not to carious dentin, and to correlate this information with the oral microbiome found in healthy teeth and those with moderate caries. RNA was purified from pulp tissue, subjected to RT-qPCR and analysed with the ΔΔCt method. Supragingival dental plaque of non-carious teeth and dentin of carious teeth were subjected to 16S targeted sequencing. Principal coordinate analysis, permutational multivariate ANOVA, and linear discriminant analysis were used to assess differences between non-carious and carious teeth. Correlations were assessed with Spearman´s test and corrected for multiple comparisons using the FDR method. The relative abundance (RA) of Lactobacillus, Actinomyces, Prevotella, and Mitsuokella was increased in carious teeth; while the RA of Haemophilus and Porphyromonas decreased. Olsenella and Parascardovia were only detected in carious teeth. Significant overexpression of interleukin 1 beta (IL1 ß), IL6, and CXCL8 was detected in pulp tissue exposed to carious dentin. IL1ß correlated positively with TLR2 and Actinomyces; yet negatively with Porphyromonas. These findings suggest that immune response of pulp tissue chronically exposed to cariogenic microbiome is triggered by proinflammatory cytokines IL1ß and IL6 and the chemokine CXCL8.

Endodontic Microbiology: A Bibliometric Analysis of the Top 50 Classics.

BACKGROUND: Citation analysis has emerged to play a significant role in recognition of the most useful areas of research. Endodontic microbiology has been a topic of interest for endodontists as well as periodontists and oral surgeons. This bibliometric analysis is aimed at identifying and reporting the characteristics of the top 50 cited articles on endodontic microbiology. METHODS: The articles were identified through a search on Web of Science (WoS), property of Clarivate Analytics database published on endodontic microbiology. The citation information of the selected articles was recorded. The Journal of Endodontics, International Endodontic Journal, Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, Dental Traumatology, and Australian Endodontic Journal were searched in the search title. Descriptive and bivariate analyses were performed using a statistical software package SPSS. Statistical analysis was performed using Shapiro-Wilk, Kruskal-Wallis, Post hoc, Mann-Kendall trend, and Spearman-rank tests. RESULTS: The 50 most cited articles were published from 1965 to 2012 with citation count varying from 1065 to 103 times. The total citation counts of articles recorded were 11,525 (WoS), 12,602 (Elseviers' Scopus), and 28,871 (Google Scholar). The most prolific years in terms of publications were 2001, 2002, and 2003, with five publications each, followed by 2005 with four. The year with most citations was 1998, with 1,330 citations, followed by 1965 and 2001, with 1,065 and 1,015 citations, respectively. A total of 136 authors contributed to the top 50 most cited articles with 27 corresponding institutions from 12 different countries. The most common methodological design was in vitro study, followed by clinic-laboratory study, literature review, systematic review and meta-analysis, and animal study. CONCLUSIONS: The present study provided a detailed list of the top 50 most cited and classic articles on microbiology in endodontics. This will help researchers, students, and clinicians in the field of endodontics as an impressive source of information.

Inflammatory Response Mechanisms of the Dentine-Pulp Complex and the Periapical Tissues.

The macroscopic and microscopic anatomy of the oral cavity is complex and unique in the human body. Soft-tissue structures are in close interaction with mineralized bone, but also dentine, cementum and enamel of our teeth. These are exposed to intense mechanical and chemical stress as well as to dense microbiologic colonization. Teeth are susceptible to damage, most commonly to caries, where microorganisms from the oral cavity degrade the mineralized tissues of enamel and dentine and invade the soft connective tissue at the core, the dental pulp. However, the pulp is well-equipped to sense and fend off bacteria and their products and mounts various and intricate defense mechanisms. The front rank is formed by a layer of odontoblasts, which line the pulp chamber towards the dentine. These highly specialized cells not only form mineralized tissue but exert important functions as barrier cells. They recognize pathogens early in the process, secrete antibacterial compounds and neutralize bacterial toxins, initiate the immune response and alert other key players of the host defense. As bacteria get closer to the pulp, additional cell types of the pulp, including fibroblasts, stem and immune cells, but also vascular and neuronal networks, contribute with a variety of distinct defense mechanisms, and inflammatory response mechanisms are critical for tissue homeostasis. Still, without therapeutic intervention, a deep carious lesion may lead to tissue necrosis, which allows bacteria to populate the root canal system and invade the periradicular bone via the apical foramen at the root tip. The periodontal tissues and alveolar bone react to the insult with an inflammatory response, most commonly by the formation of an apical granuloma. Healing can occur after pathogen removal, which is achieved by disinfection and obturation of the pulp space by root canal treatment. This review highlights the various mechanisms of pathogen recognition and defense of dental pulp cells and periradicular tissues, explains the different cell types involved in the immune response and discusses the mechanisms of healing and repair, pointing out the close links between inflammation and regeneration as well as between inflammation and potential malignant transformation.

Association between Helicobacter pylori infection and dental pulp reservoirs in Japanese adults.

BACKGROUND: Helicobacter pylori (H. pylori) colonize the stomach and are considered an etiological agent of gastric cancer. The oral cavity is a transmission route to the stomach, but the exact site of colonization has not yet been explicated. Our study investigated the association between H. pylori infection and presence in oral samples. METHODS: Dental pulp, supragingival plaque, and saliva from 192 patients visiting the Dentistry's outpatient clinic were collected for testing. The H. pylori ureA gene was identified via Nested PCR. Urine anti-H. pylori antibody test was utilized to detect infection. RESULTS: Twenty-five subjects were found to be antibody-positive. PCR analysis of dental pulp revealed that 23 subjects possessed the ureA gene. Twenty-one subjects were positive for both antibodies and genes in dental pulp. PCR testing revealed that 2 subjects were positive in dental plaque but negative for saliva. The subjects positive for H. pylori in dental pulp expressed clinical signs of severe dental caries. CONCLUSIONS: H. pylori infected subjects expressed H. pylori in samples from the oral cavity. The main reservoir for infection within the oral cavity was determined to be dental pulp. Moreover, H. pylori are likely transmitted from dental caries to the root canal.

Paleoproteomics of the Dental Pulp: The plague paradigm.

Chemical decomposition and fragmentation may limit the detection of ancient host and microbial DNA while some proteins can be detected for extended periods of time. We applied paleoproteomics on 300-year-old dental pulp specimens recovered from 16 individuals in two archeological funeral sites in France, comprising one documented plague site and one documented plague-negative site. The dental pulp paleoproteome of the 16 teeth comprised 439 peptides representative of 30 proteins of human origin and 211 peptides representative of 27 proteins of non-human origin. Human proteins consisted of conjunctive tissue and blood proteins including IgA immunoglobulins. Four peptides were indicative of three presumable Yersinia pestis proteins detected in 3/8 dental pulp specimens from the plague-positive site but not in the eight dental pulp specimens collected in the plague-negative site. Paleoproteomics applied to the dental pulp is a new and innovative approach to screen ancient individuals for the detection of blood-borne pathogens and host inflammatory response.

Effect of Residual Bacteria on the Outcome of Pulp Regeneration In Vivo.

It is not known to what extent residual infection may interfere with the success of pulp regeneration procedures. The aim of this study was to determine, radiographically and histologically, the effect of residual bacteria on the outcome of pulp regeneration mediated by a tissue-engineered construct as compared with traditional revascularization. Periapical lesions were induced in 24 canine teeth of 6 ferrets. After disinfection with 1.25% NaOCl and triple antibiotic paste, ferret dental pulp stem cells, encapsulated in a hydrogel scaffold, were injected into half the experimental teeth. The other half were treated with the traditional revascularization protocol with a blood clot scaffold. After 3 mo, block sections of the canine teeth were imaged radiographically and processed for histologic and histobacteriologic analyses. Associations between variables of interest were evaluated through mixed effects regression models. There were no significant differences between the 2 experimental groups in radiographic root development ( P > 0.05). There was a significant association between the presence of persistent periapical radiolucency and root wall thickness ( P = 0.02). There was also no significant difference in histologic findings between the 2 experimental groups ( P > 0.05). The presence of residual bacteria was significantly associated with lack of radiographic growth ( P < 0.001). The amount of dentin-associated mineralized tissue formed in teeth with residual bacteria was significantly less than in teeth with no residual bacteria ( P < 0.001). Residual bacteria have a critical negative effect on the outcome of regenerative endodontic procedures.

Microbial Reduction by Two Chemical-Mechanical Protocols in Primary Teeth with Pulp Necrosis and Periradicular Lesion - An In Vivo Study

The objective of this study was to determine the efficacy of chemical-mechanical procedures of two endodontic protocols for septic content reduction of root canals from primary teeth with pulp necrosis and periradicular lesion. Twenty-four primary root canals with pulp necrosis and periradicular lesion were divided into two treatment groups (n=12): multiple-visit and single-visit protocols. Samples were collected using sterile paper points before and after endodontic cleaning followed by microbiological identification through checkerboard DNA-DNA hybridization. Statistical analysis was performed using Proportion Test for score=0 comparing the findings before and after treatment for each group (Wilcoxon's test) as well as the differences in scores between protocols (Mann-Whitney's test) (p<0.05). Data were expressed as prevalence (presence or absence) and estimate of the average count (x105 cells) of each species. Differences in proportions of score=0 prior to treatment were non-significant (p=0.415), demonstrating equivalence between groups. A significant increase in score=0 was detected after treatment for both groups (p<0.0001). Single-visit protocol achieved a significantly greater reduction in mean scoring following endodontic treatment (p=0.024). Both protocols were capable of significantly reducing septic content in root canals of primary teeth with periradicular lesion. Moreover, single-visit protocol showed greater efficacy in reducing endodontic infection.

O objetivo deste estudo foi determinar a eficácia das manobras químico-mecânicas de dois protocolos endodônticos, na redução do conteúdo séptico de canais radiculares de dentes decíduos com polpa necrosada e lesão perirradicular. Vinte e quatro canais radiculares decíduos com necrose pulpar e lesão perirradicular foram divididos em dois grupos de tratamento (n=12): multisessões e sessão única. Amostras foram coletadas usando pontas de papel estéreis, antes e após a limpeza endodôntica, seguido de identificação microbiológica por hibridização DNA-DNA checkerboard. A análise estatística foi realizada usando teste de proporções para escore=0, comparando os achados antes e após tratamento para cada grupo (teste de Wilcoxon) e as diferenças dos escores entre os protocolos (teste de Mann-Whitney) (p<0,05). Os dados foram expressos em prevalência (presença ou ausência) e contagem média (x105 células) de cada espécie. As diferenças nas proporções de escore=0 antes do tratamento não foram significativas (p=0,415), mostrando equivalência entre os grupos. Um aumento significativo de escore=0 foi detectado após o tratamento para ambos os grupos (p<0,0001). O protocolo de sessão única mostrou uma redução significativamente maior dos escores médios após o tratamento endodôntico (p=0,024). Ambos os protocolos são capazes de reduzir significativamente o conteúdo séptico de canais radiculares de dentes decíduos com lesão perirradicular. Entretanto, o protocolo de sessão única mostrou uma maior eficácia na redução da infecção endodôntica.

Development of an ex vivo coculture system to model pulpal infection by Streptococcus anginosus group bacteria.

INTRODUCTION: Streptococcus anginosus group (SAG) bacteria are opportunistic pathogens and a major cause of pulpal infection and subsequent abscess formation. Understanding of the processes involved in SAG oral infections has been limited by the lack of an appropriate model system. METHODS: Cocultures of SAG bacteria and mammalian tooth slices were maintained using a combination of Dulbecco modified eagle medium and brain-heart infusion broth at 60 rpm, 37°C, 5% CO(2) for 4, 8, or 24 hours before histologic examination or staining with acridine orange/ethidium bromide. Tooth slices were also incubated as described with SAG bacteria stained with fluorescein diacetate. Pulps were extirpated from infected and sterile cultured tooth slices, messenger RNA was extracted and converted to complementary DNA, and polymerase chain reaction were performed for genes encoding tumor necrosis factor α, interleukin 1ß, and interleukin-6. RESULTS: SAG bacteria were able to adhere directly to the central region of the pulpal matrix in small foci that were associated with a localized matrix breakdown. Acridine orange-ethidium bromide staining and cell counts indicated a decrease in mammalian cell viability with increasing incubation times in the presence of SAG bacteria. The increased expression of tumor necrosis factor α and interleukin 1ß was detected in infected tooth slices. CONCLUSIONS: A novel ex vivo model system has been developed that allows coculture of SAG bacteria with a 3-dimensional organotypic tooth slice. The model allows observation of bacterial growth patterns and subsequent responses from host tissues. Therefore, it may be of future use in testing the efficacy of both antimicrobial and anti-inflammatory treatments for use in endodontic therapy.

Toll-like receptors, LPS, and dental monomers.

Unreacted monomers released from dental resin-based composites at non-cytotoxic concentrations cause a depletion of glutathione and an increase of reactive oxygen species (ROS), leading to, e.g., DNA damage and apoptosis. ROS-sensitive MAP-kinases are activated by HEMA and TEGDMA. MAP-kinases are also involved in the bacteria-triggered cell responses of the innate immune system, e.g., after bacterial lipopolysaccharide (LPS) binding to the Toll-like receptor (TLR) 4. Therefore, both bacteria and monomers imply environmental stress to pulp tissue, and they may influence the target cell reactions in a combined way. In macrophages, cell-surface antigens and cytokines were up-regulated after exposure to LPS, but TEGDMA caused a significant down-regulation. Regulation was dependent on exposure time, indicating that LPS and TEGDMA act differently on MAP-kinases. Furthermore, the cell type played a decisive role. Inhibition of the immune response may result in a decrease in inflammatory symptoms and/or a reduced defense capacity against bacteria.

Oral biofilm challenge regulates the RANKL-OPG system in periodontal ligament and dental pulp cells.

Inflammatory bone destruction triggered by oral bacteria is a hallmark of chronic and apical periodontitis. Receptor activator of NF-κB ligand (RANKL) activates bone resorption, whereas osteoprotegerin (OPG) blocks its action. These are members of the tumor necrosis factor ligand and receptor families, respectively. Although individual oral pathogens are known to regulate RANKL and OPG expression in cells of relevance to the respective diseases, such as periodontal ligament (PDL) and dental pulp (DP) cells, the effect of polymicrobial oral biofilms is not known. This study aimed to investigate the effect of the Zürich in vitro supragingival biofilm model on RANKL and OPG gene expression, in human PDL and DP cell cultures, by quantitative real-time polymerase chain reaction. RANKL expression was more pronouncedly up-regulated in DP than PDL cells (4-fold greater), whereas OPG was up-regulated to a similar extent. The RANKL/OPG ratio was increased only in DP cells, indicating an enhanced capacity for inducing bone resorption. The expression of pro-inflammatory cytokine interleukin-1ß was also increased in DP, but not PDL cells. Collectively, the high responsiveness of DP, but not PDL cells to the supragingival biofilm challenge could constitute a putative pathogenic mechanism for apical periodontitis, which may not crucial for chronic periodontitis.

Response of human dental pulp to calcium hydroxide paste preceded by a corticosteroid/ antibiotic dressing agent

Aim: To evaluate the treatment with corticosteroid/antibiotic dressing in pulpotomy with calciumhydroxide. Methods: Forty-six premolars were pulpotomized and randomly assigned into 3groups. In Group I pulpal wound was directly capped with calcium hydroxide, and Group II and Group III received corticosteroid/antibiotic dressing for 10 min or 48 h, respectively, before pulp capping. Teeth were processed for histological analysis after 7, 30 or 60 days to determine inflammatory cell response, tissue disorganization, dentin bridge formation and presence of bacteria.Attributed scores were analyzed by Kruskal-Wallis and Mann-Whitney tests (á=0.05). Results:On the 7th day, all groups exhibited dilated and congested blood vessels in the tissue adjacent to pulpal wound. The inflammatory cell response was significantly greater in Group III (p<0.05). On the 30th day, in all groups, a thin dentin matrix layer was deposited adjacent to the pulpal wound and a continuous odontoblast-like cell layer underlying the dentin matrix was observed. On the60th day, all groups presented a thick hard barrier characterized by an outer zone of dystrophic calcification and an inner zone of tubular dentin matrix underlined by a defined odontoblast-like celllayer. Conclusions: Within the limitations of present study, considering that the treatment was performed in healthy teeth, it may be concluded that the use of a corticosteroid/antibiotic dressing before remaining tissue protection with calcium hydroxide had no influence on pulp tissue healing.

Adaptive calcified matrix response of dental pulp to bacterial invasion is associated with establishment of a network of glial fibrillary acidic protein+/glutamine synthetase+ cells.

We report evidence for anatomical and functional changes of dental pulp in response to bacterial invasion through dentin that parallel responses to noxious stimuli reported in neural crest-derived sensory tissues. Sections of resin-embedded carious adult molar teeth were prepared for immunohistochemistry, in situ hybridization, ultrastructural analysis, and microdissection to extract mRNA for quantitative analyses. In odontoblasts adjacent to the leading edge of bacterial invasion in carious teeth, expression levels of the gene encoding dentin sialo-protein were 16-fold greater than in odontoblasts of healthy teeth, reducing progressively with distance from this site of the carious lesion. In contrast, gene expression for dentin matrix protein-1 by odontoblasts was completely suppressed in carious teeth relative to healthy teeth. These changes in gene expression were related to a gradient of deposited reactionary dentin that displayed a highly modified structure. In carious teeth, interodontoblastic dentin sialo-protein(-) cells expressing glutamine synthetase (GS) showed up-regulation of glial fibrillary acidic protein (GFAP). These cells extended processes that associated with odontoblasts. Furthermore, connexin 43 established a linkage between adjacent GFAP(+)/GS(+) cells in carious teeth only. These findings indicate an adaptive pulpal response to encroaching caries that includes the deposition of modified, calcified, dentin matrix associated with networks of GFAP(+)/GS(+) interodontoblastic cells. A regulatory role for the networks of GFAP(+)/GS(+) cells is proposed, mediated by the secretion of glutamate to modulate odontoblastic response.

Anti-inflammatory effect of catechin on cultured human dental pulp cells affected by bacteria-derived factors.

Catechins (bioactive polyphenols in green tea) are known to exhibit potent anti-inflammatory properties. However, the anti-inflammatory effects of catechins on inflamed dental pulp tissue are not known. In this study, we investigated the effect of epigallocatechin-3-gallate (EGCG) and epicatechin gallate (ECG), the major components of green tea catechins, on the expression of pro-inflammatory cytokines and adhesion molecules in human dental pulp cells stimulated with bacteria-derived factors such as lipopolysaccharide (LPS) and peptidoglycan (PG). The expression of interleukin (IL)-6 and of IL-8 was examined using the reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assays. The expression of intercellular adhesion molecule-1 (ICAM-1) and of vascular cell adhesion molecule-1 (VCAM-1) on dental pulp cells was analyzed using flow cytometry. The presence of EGCG and ECG significantly reduced, in a concentration-dependent manner, the expression of IL-6 and IL-8 in dental pulp cells exposed to LPS or PG. Increased expression of ICAM-1 and VCAM-1 on the dental pulp cells in response to bacterial components was also decreased by treatment with EGCG and ECG. These findings suggest that green tea catechins may prevent the exacerbation of pulpitis.

Evaluation of dental pulp temperature rise during photo-activated decontamination (PAD) of caries: an in vitro study.

Photo-activated decontamination (PAD) has been reported in caries treatment as an aid in dentine decontamination. The aim of this study is to verify the harmlessness for pulp vitality of photo-activated decontamination (PAD) in caries treatment. Twenty freshly extracted single-rooted teeth were used. Deep class I cavities with a

Microbiological and microscopic analysis of the pulp of non-vital traumatized teeth with intact crowns

OBJECTIVE: This study evaluated the presence of microorganisms and analyzed microscopically the pulp of 20 traumatized human teeth with intact crowns and clinical diagnosis of pulp necrosis, based on the association of at least three of the clinical criteria: crown discoloration, negative response to thermal and electric pulp vitality tests, positive response to vertical and horizontal percussion, pain on palpation or mobility. MATERIAL AND METHODS: Microbiological collection was performed from the root canals to evaluate the presence of microorganisms. The pulp samples were stained with hematoxylin and eosin (H.E.) for histological evaluation of possible morphological alterations. RESULTS: Analysis of results was performed by statistical tests (linear regression test and diagnostic analysis) and subjective analysis of the sections stained with H.E. and revealed that only 15 percent of the sample did not exhibit microbial development. The time elapsed between dental trauma and onset of endodontic intervention ranged from 15 days to 31 months; the percussion test presented high sensitivity (80 percent) for detection of microorganisms in the root canal of traumatized teeth; 3 teeth (15 percent) did not present pulp tissue, being characterized as complete autolysis; analysis of pulp samples was performed on the other 17 cases, among which 3 (15 percent) exhibited partial necrosis without possibility of repair and 14 presented complete necrosis; none of the clinical criteria employed for the diagnosis of pulp necrosis in traumatized teeth was pathognomonic. CONCLUSIONS: The present results allowed the following conclusions: with regard to microbiological findings, 85 percent of teeth presented microorganisms in the root canal, despite the presence of an intact crown. Concerning the microscopic findings, 100 percent of traumatized teeth presented pulp necrosis; the pulp vitality tests based on pulp response to heat, cold and vertical percussion ...

Angiogenic signaling triggered by cariogenic bacteria in pulp cells.

The inflammation observed in the dental pulp of teeth with deep caries lesions is characterized by a significant increase in blood vessel density. It is known that lipoteichoic acid (LTA) from Gram-positive cariogenic bacteria induces expression of vascular endothelial growth factor (VEGF) in dental pulp cells. The hypothesis underlying this study was that LTA induces VEGF expression in dental pulp cells through TLR2 and PI3k/Akt signaling. Odontoblast-like cells (MDPC-23) and undifferentiated pulp cells (OD-21) were exposed to LTA from Streptococcus sanguis, and the role of TLR2, PI3K/Akt, and IKK signaling in LTA-induced VEGF expression was evaluated. These studies demonstrated that TLR2 signaling through the PI3K-Akt pathway is necessary for LTA-induced VEGF expression in pulp cells. In contrast, inhibition of IKK signaling did not prevent VEGF up-regulation in response to LTA. Understanding signaling pathways triggered by cariogenic bacteria may reveal novel therapeutic targets for the clinical management of pulpitis.

CCL20 production is induced in human dental pulp upon stimulation by Streptococcus mutans and proinflammatory cytokines.

INTRODUCTION: Pulpitis is characterized by the marked infiltration of inflammatory cells in response to an invasion of caries-related bacteria. It is well known that chemokines regulate the trafficking of lymphocytes, and CC chemokine ligand 20 (CCL20) has been recently shown to play a crucial role in the recruitment of memory T cells and immature dendritic cells into inflammatory lesions. We previously reported that CCL20 was mainly expressed in microvascular endothelial cells and macrophages that accumulated in inflamed pulp tissues and that its specific receptor, CCR6, was expressed on infiltrated lymphocytes. However, the mechanism of CCL20 expression remains unclear. METHODS AND RESULTS: In this study, we investigated the expression of CCL20 in monocytes/macrophages, endothelial cells, and pulpal fibroblasts after stimulation with Streptococcus mutans, a representative of caries-related bacteria, or proinflammatory cytokines. CCL20 messenger RNA was detected by reverse transcription-polymerase chain reaction in inflamed pulp, but not in clinically normal pulp. By enzyme-linked immunosorbent assay, S. mutans induced a human monocytic cell line, differentiated macrophage-like THP-1 cells, and human umbilical vein endothelial cells (HUVEC) to produce an increased amount of CCL20. Lipoteichoic acid from S. mutans also elicited CCL20 production by HUVEC. Moreover, CCL20 production from pulpal fibroblasts was increased by stimulation with inetrleukin-1beta and tumor necrosis factor-alpha. CONCLUSION: Our results indicate that CCL20 expression is induced by stimulation with caries-related bacteria that have invaded deeply into the dentinal tubules as well as by proinflammatory cytokines in the inflamed pulpal lesions. It may be involved in the progression of pulpitis via accumulation of inflammatory cells.

Expression of toll-like receptor 2 and 4 in dental pulp.

Toll-like receptors (TLRs) are important factors in innate immune responses because they mediate signals from bacterial cell wall components during inflammatory reactions. However, the role of TLR in dental pulp, which is bounded by hard tissues, is little understood. The present study investigated the expression of TLR-2 and TLR-4 in experimentally inflamed pulp by quantitative real-time polymerase chain reaction and immunohistochemistry. Total RNA isolated from pulp tissue from 0 to 72 hours after bacterial dentinal infection. The TLR-2 messenger RNA (mRNA) level was 30-fold higher than the TLR-4 mRNA level at 9 hours. The TLR-2 mRNA level in pulp began to increase by 3 hours after bacterial infection, reaching a maximum level after 9 hours and gradually decreasing from 9 to 72 hours. Numerous TLR-2- and CD64-positive cells detected on macrophage and dendritic-like cells, TLR-4-positive cells detected a little in the pulp at 9 hours. These results suggest that TLR-2 may be mainly regulated during the early stage of pulp inflammation triggered by bacterial infection.

Histopathologic study of physiological and pathological resorptions in human primary teeth.

This study presents a histological analysis through optical microscopy of primary teeth with physiological and pathological resorptions to outline the histological profile of resorptions. Sixty teeth were examined: 19 primary teeth with physiological resorption and 41 primary teeth with pathological resorption. To analyze the histological conditions of the pulp, periradicular tissue, and the resorption areas, and to investigate the presence, intensity, and location of bacteria, slides were prepared using the hematoxylin-eosin and the Brown-Brenn techniques. For the teeth with physiological resorption, normal pulps and no evidence of bacteria were found. For the teeth with pathological resorption, pulpal alterations, atypical resorption, and bacteria were observed.