Pulpal Response Research Articles

Pulpal response following photo-biomodulation with a 904-nm diode laser: a double-blind clinical study.

The aim of this study was to evaluate pulpal responses in healthy human teeth to photo-biomodulation therapy (PBMT) with 904-nm GaAs diode laser. The study followed a double-blind split mouth design, with a randomly selected maxillary first premolar acting as a sham-irradiated control tooth, and the contralateral tooth receiving active laser treatment. Two coded but otherwise identical laser probes (Irradia™, SpectraMedics Ltd., NC, USA) were used to deliver the sham (placebo) and laser radiation, with both the operator and patient unaware of each probe's identity. The selection of teeth for sham or laser irradiation was randomised for each treatment. Pulpal responses were assessed using electric pulp testing (EPT), 2min prior to exposure, and immediately after laser irradiation (60s, 30mW average power, 25Hz pulse frequency, 3.6J/cm2). Treatment effects were analysed using the Wilcoxon-signed rank test. A total of 30 participants provided written informed consent. Majority of the participants (66.7%) demonstrated an analgesic effect following PBMT (elevated EPT scores); however, nine participants (30%) reported the lower EPT scores than the control. Both the treatment effects (stimulation and analgesia) were significant compared to the placebo. In most individuals, PBMT of healthy teeth with a 904-nm GaAs diode laser can induce analgesia, as witnessed by elevated EPT scores. A converse effect can occur in a minority of subjects.

The Effect of Low Level Laser Therapy on Direct Pulp Capping in Dogs.

Introduction: The aim of this study was to determine the histologic effect of low level laser therapy (LLLT) with or without the use of mineral trioxide aggregate (MTA) on exposed pulp tissues of dogs. Methods: Twenty-five premolar teeth in three healthy mature dogs were randomly divided into five groups. In group 1, the pulp tissue was capped with MTA. In groups 2 and 3, before capping with MTA, the exposure site was irradiated by low power lasers at 630 nm (20 mW, 150 seconds, 7.5 J/cm2) and 810 nm (peak power 80 W, average power 50 mW, 1500 Hz, 50 seconds, 6.25 J/cm2) wavelengths, respectively. In groups 4 and 5, the exposure site was irradiated similar to that described in groups 2 and 3, but the pulp tissue was covered by gold foil instead of MTA. After 2 months, the animals were sacrificed and the samples were prepared for histologic evaluation. Results: There were differences in pulpal response and dentinal barrier formation among the study groups. The morphology of pulpal tissue and the integrity of dentinal barrier and formation of odontoblastic layer were more favorable in the first three groups. The occurrence of extensive and intense inflammation and necrosis was more frequent in groups 4 and 5. Conclusion: Under the conditions used in this study, the presence of MTA as a pulp capping material was more important than laser therapy in the success of direct pulp capping (DPC) treatment. MTA proved to be an effective material either alone or in combination with laser irradiation in vital pulp therapy.

<b>Histological evaluation of the rat dental pulp after indirect capping with sildenafil or L-NAME incorporated into a bioadhesive thermoresponsive system

We evaluated the histological dental pulp state in vivo after indirect pulp capping using sildenafil or L G -nitro-L-arginine (L-NAME), incorporated into a new bioadhesive thermoresponsive system (BTS). Male Wistar rats were subjected to an upper and lower first molar class I cavity preparation followed by indirect pulp capping with sildenafil or L-NAME. Calcium hydroxide (CaOH 2 ) was used as a control. The teeth and surrounding bone were properly dissected and processed for Nissl’s staining. Pulp state was evaluated considering the morphological aspects of the inflammatory response, type of inflammatory infiltrate, organization of the odontoblast layer, blood vessel condition, and presence of abscesses or necrosis. The results were expressed as average of observations. The most intense inflammatory response was observed 3 days after the cavity preparation. No identified changes were detected in the dental pulp response of the molars treated with L-NAME compared with those treated with CaOH 2 . A dual effect was observed in the teeth treated with sildenafil. While low sildenafil concentration (0.015% w w -1 ) promoted effects comparable to CaOH 2 , at a higher concentration (0.15% w w -1 ), sildenafil caused a severe inflammatory response and pulp necrosis. This pioneering suggest that NO pathway activity may be a determinant in the process of dental pulp healing.

Diabetes Mellitus And Reparative Response Of Dental Pulp

Abstract Anatomically, dental pulp is connective tissue and specific microcirculatory system with significant reparatory abilities intending to preserve pulp vitality. Various therapeutic approaches in the treatment of affected pulp may be compromised by various factors leading to treatment failure. Due to microcirculatory system disorders, treatment of affected dental pulp in patients with diabetes mellitus (DM) is additional challenge. The function and levels of growth factors could be altered in various diabetic tissues including dental pulp. Among them are growth factors important for reparative response of the pulp. There are experimental evidences that DM impede dental pulp reparation. Therefore, clinical procedures aiming to preserve vitality of diabetic dental pulp should be applied with caution. The aim of this paper is to present basic factors and parameters that affect reparative response of dental pulp in patients with DM.

The Novel NF‐κB Inhibitor, MTI‐II Peptide Anti‐Inflammatory Drug, Suppresses Inflammatory Responses in Odontoblast‐Like Cells

Regulation of inflammation is important for pulp wound healing, including protective responses by odontoblast-like cells. However, methods for directly regulating pulp inflammation have not yet been described. The inflammatory response is mediated by a transcription factor, nuclear factor-κB (NF-κB), which activates inflammatory cytokines including tumor necrosis factor (TNF)-α. Macromolecular translocation inhibitor II (MTI-II) was previously demonstrated as an enhancer of the transcriptional activity of glucocorticoid-bound glucocorticoid receptor. Recently, a MTI-II peptide anti-inflammatory drug (MPAID) was bioengineered from the structure of MTI-II as an inhibitor of NF-κB transactivation. Here, we examined the effects of MTI-II and MPAID on the inflammatory responses of odontoblast-like cells. TNF-α inhibited alkaline phosphatase (ALP) activity, a marker of odontoblast/osteogenic differentiation, and induced NF-κB transcriptional activity in KN-3 cells, which are odontoblast-like cells derived from dental papilla cells of rat incisors, without affecting their viability. Exogenous expression of MTI-II suppressed the NF-κB transcriptional activity induced by TNF-α or overexpression of p65 (a main subunit of NF-κB) in the cells, whereas it failed to inhibit degradation of IκBα and nuclear translocation of p65 after TNF-α treatment, suggesting that MTI-II inhibits NF-κB transcriptional activity by modulating the duration of DNA binding by p65. MPAID also inhibited TNF-α-induced NF-κB transcriptional activity, the mRNA expression of IL-6 and IL-8, and IL-6 production. Furthermore, pretreatment of the cells with MPAID restored the inhibitory effect of TNF-α on ALP activity. These results suggest that MPAID may be able to regulate the inflammatory response and maintain a protective response of dental pulp. J. Cell. Biochem. 117: 2552-2558, 2016. © 2016 Wiley Periodicals, Inc.

Penetration Capacity, Color Alteration and Biological Response of Two In-office Bleaching Protocols.

Hydrogen peroxide (H2O2) penetrates into the dental hard tissues causing color alteration but also alterations in pulpal tissues. Hard-tissue penetration, color alteration and the pulp response alterations were evaluated for two in-office bleaching protocols with H2O2. For trans-enamel/dentin penetration and color alteration, discs of bovine teeth were attached to an artificial pulp chamber and bleached according to the groups: BLU (20% H2O2 - 1x50 min, Whiteness HP Blue); MAX (35% H2O2 - 3x15 min, Whiteness HP Maxx); Control (1x50 min, placebo). Trans-enamel/dentin penetration was quantified based on the reaction of H2O2 with leucocrystal violet and the color analyzed by CIELab System. Twenty Wistar rats were divided into two groups (BLU and MAX) and their maxillary right molars were treated according to the same protocols of the in vitro study; the maxillary left molars were used as controls. After 2 days, the animals were killed and their maxillae were examined by light microscopy. The inflammation of pulp tissue was scored according to the inflammatory infiltrate (1, absent; 2, mild; 3, moderate; 4, severe/necrosis). Data were analyzed by statistical tests (α=0.05). MAX showed higher trans-enamel/dentinal penetration of H2O2 (p<0.05). The color alteration was similar for both groups (p>0.05), and different when compared to Control group (p<0.05). MAX showed severe inflammation in the upper thirds of the coronal pulp, and BLU showed moderate inflammation (p<0.05). In-office bleaching protocols using lower concentrations of hydrogen peroxide should be preferred due to their reduced trans-enamel/dentinal penetration since they cause less pulp damage and provide same bleaching efficiency.

Epigenetic regulation in dental pulp inflammation

Dental caries, trauma, and other possible factors could lead to injury of the dental pulp. Dental infection could result in immune and inflammatory responses mediated by molecular and cellular events and tissue breakdown. The inflammatory response of dental pulp could be regulated by genetic and epigenetic events. Epigenetic modifications play a fundamental role in gene expression. The epigenetic events might play critical roles in the inflammatory process of dental pulp injury. Major epigenetic events include methylation and acetylation of histones and regulatory factors, DNA methylation, and small non-coding RNAs. Infections and other environmental factors have profound effects on epigenetic modifications and trigger diseases. Despite growing evidences of literatures addressing the role of epigenetics in the field of medicine and biology, very little is known about the epigenetic pathways involved in dental pulp inflammation. This review summarized the current knowledge about epigenetic mechanisms during dental pulp inflammation. Progress in studies of epigenetic alterations during inflammatory response would provide opportunities for the development of efficient medications of epigenetic therapy for pulpitis.

Expression of Mineralization Markers during Pulp Response to Biodentine and Mineral Trioxide Aggregate

IntroductionThe purpose of this study was to compare the cell viability of dental pulp cells treated with Biodentine (Septodont, Saint-Maur, France) and mineral trioxide aggregate (MTA) and the in vitro and in vivo expression of mineralization markers induced by the 2 materials. MethodsHuman dental pulp cells isolated from 6 permanent teeth were stimulated with Biodentine and MTA extracts. Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and quantitative reverse-transcriptase polymerase chain reaction was used to determine the expression of mineralization markers. Specimens of teeth from dogs treated with Biodentine and MTA after pulpotomy were used to determine the presence of osteopontin and alkaline phosphatase by immunohistochemistry and runt-related transcription factor 2 by immunofluorescence. ResultsNo significant differences in cell viability were found between MTA and Biodentine extracts and controls after 24 and 48 hours (P > .05). After 48 hours, osteopontin (SPP1), alkaline phosphatase (ALP), and runt-related transcription factor 2 (RUNX2) expression was higher in MTA and Biodentine than in controls (P < .05). Osteopontin staining was more intense and spread over a greater number of areas in Biodentine than in MTA samples (P < .0001). Alkaline phosphatase staining of a mineralized tissue bridge was significantly different between materials (P < .0001), but no difference in alkaline phosphatase staining of pulp tissue was found between MTA and Biodentine (P = .2). Also, no significant difference in the number of cells labeled for runt-related transcription factor 2 by immunofluorescence was observed between materials (P > .05). ConclusionsBiodentine stimulated similar markers as MTA, but staining was more intense and spread over a larger area of the pulp tissue.

Thixotropic Flow Behaviour in Chemical Pulp Fibre Suspensions

This paper presents results on the thixotropic behaviour of hardwood and softwood pulp fibre suspensions. Three rheological tests including hysteresis-loops, creep tests, and step-wise experiments were used to investigate the thixotropic rheology. Both suspensions exhibited a plateau in their flow curves where a slight change of the applied shear stress led to a dramatic change in the corresponding shear rates. During creep experiments under controlled stress, they evolved either towards a rapid shear (liquid regime) or stoppage (solid regime), depending on the relative values of the imposed stress, leading to a viscosity bifurcation around a critical stress. The transient response of pulp to step changes in shear rate was marked by a characteristic time, which can be used to understand the rate of structural change for pulp suspensions. Moreover, the yielding and thixotropic behaviour of the pulp suspensions were highly dependent on shear history and the time of rest prior to the measurement.

Combined effects of mineral trioxide aggregate and human placental extract on rat pulp tissue and growth, differentiation and angiogenesis in human dental pulp cells

Objective The aim of this study was to evaluate the combined effects of mineral trioxide aggregate (MTA) and human placental extract (HPE) on cell growth, differentiation and in vitro angiogenesis of human dental pulp cells (HDPCs) and to identify underlying signal transduction mechanisms. In vivo dental pulp responses in rats for a pulp-capping agent were examined. Materials and methods MTS assay. ALP activity test, alizarin red S staining and RT-PCR for marker genes were carried out to evaluate cell growth and differentiation. HUVEC migration, mRNA expression and capillary tube formation were measured to evaluate angiogenesis. Signal transduction was analysed using Western blotting and confocal microscopy. The pulps of rat maxillary first molars were exposed and capped with either MTA or MTA plus HPE. Histologic observation and scoring were performed. Results Compared to treatment of HDPCs with either HPE or MTA alone, the combination of HPE and MTA increased cell growth, ALP activity, mineralized nodules and expression of marker mRNAs. Combination HPE and MTA increased migration, capillary tube formation and angiogenic gene expression compared with MTA alone. Activation of Akt, mammalian target of rapamycin (mTOR), p38, JNK and ERK MAPK, Akt, and NF-κB were significantly increased by combining HPE and MTA compared with MTA alone. Pulp capping with MTA plus HPE in rats showed superior dentin bridge formation, odontoblastic layers and dentinal tubules and lower inflammatory cell response, compared to the MTA alone group. Conclusions This study demonstrates for the first time that the use of MTA with HPE promotes cell growth, differentiation and angiogenesis in HDPCs, which were associated with mTOR, MAPK and NF-κB pathways. Direct pulp capping with HPE plus MTA showed superior results when compared with MTA alone. Thus, the combination of MTA and HPE may be useful for regenerative endodontics.

Success Rate of MTA Pulpotomy on Vital Pulp of Primary Molars: A 3-Year Observational Study

IntroductionVital pulp therapy is a major contributor in the preservation of primary dentition after caries affliction. Introduction of mineral trioxide aggregate (MTA) has revolutionized such treatment.AimThe aim of our study was to evaluate and correlate the effects of MTA clinically and radiographically on pulpotomized primary molars till their exfoliation or extraction followed by histological evaluation.Study designThis is an observational study.Materials and methodsA total of 25 teeth were selected from 5- to 8-year-old children requiring pulp therapy on the basis of inclusion and exclusion criterion. The teeth were treated by conventional pulpotomy technique under aseptic conditions using MTA and were immediately restored with stainless steel crown. The teeth were assessed postoperatively till 36 months. The exfoliated or extracted teeth were examined histologically.ResultsThe pulpotomized teeth were vital with no adverse clinical findings during the observation period. After 3 months, one tooth showed internal resorption, but the same was not observed after 12 months. Pulp canal obliteration was seen in three cases. At the end of the study, five teeth were exfoliated and one tooth was extracted for maintaining arch symmetry. The histological examination of extracted tooth revealed the presence of healthy pulp and the area of true calcification. Remaining exfoliated teeth presented dentin bridge formation.StatisticsFrequencies and percentages were used for descriptive statistics. Fisher’s exact tests were used to see the difference between clinical and radiological findings. The probability value was fixed at 5% level of significance.ConclusionThe response of pulp in primary teeth to MTA was favorable in all cases from clinical and radiographic perspective, and histological evaluation confirmed the observation.How to cite this articleGodhi B, Tyagi R. Success Rate of MTA Pulpotomy on Vital Pulp of Primary Molars: A 3-Year Observational Study. Int J Clin Pediatr Dent 2016;9(3):222-227.

Influence of the orthognathic surgical procedure Le Fort I osteotomy on the vascularity and neurosensory response of the dental pulp: A systematic review.

Abnormalities of the midface and maxilla are frequently corrected using Le Fort I surgery. This osteotomy passes near the apices of the maxillary teeth, severing the blood vessels and nerves supplying the teeth. The aim of this review was to determine the effect of Le Fort I osteotomy on pulpal vascularity and neurosensory response. A systematic search of the literature was performed in PubMed/ Medline, Google Scholar, EMBASE, and ISI Web of Knowledge from 1969 up to and including December 2015 using the following key words: Le Fort 1, tooth vitality, maxillary osteotomy, pulp, orthognathic. Reference lists of relevant articles were hand-searched for additional articles. Sixty-two studies were located by initial screening; 38 did not meet the eligibility criteria; three were excluded after full-text review, 13 were excluded after quality assessment, leaving nine studies eligible that met all inclusion criteria for this systematic review. The postoperative follow-up period of the included studies ranged from 3 months to 28 months. Five studies assessed pulpal blood flow using laser Doppler flowmetry and eight studies assessed the pulpal neurosensory response using electric pulp testing. There is a decrease in pulpal vascularity and neurosensory response following a Le Fort I osteotomy in the early postoperative period (1 to 10 days) that is likely temporary. Further controlled clinical studies with standardized parameters are required to determine the long-term effects of Le Fort I osteotomy on the vascular and neural healing of the dental pulp.

Histological response of human pulps capped with calcium hydroxide and a self-etch adhesive containing an antibacterial component.

Aim:To compare human pulp tissue response following direct pulp capping with calcium hydroxide and a self-etch adhesive containing antibacterial component.Materials and Methods:Sixty-six erupted sound premolars scheduled to be extracted for orthodontic reasons were selected from 17 human subjects. Pulp exposures were made. Direct pulp capping was then performed using calcium hydroxide and a self-etch adhesive containing antibacterial component in its primer. The teeth were then restored with composite resin. Two teeth were maintained intact as a control group. After 7 and 30 days, teeth were extracted and processed for light microscopic examination using a histological scoring system. The teeth were divided into four groups (N = 16) according to the pulp capping materials used and their days of extraction. The results were then statistically analyzed by Mann-Whitney U-test.Results:After the 7-day observation period, the inflammatory reaction to the self-etch adhesive containing antibacterial component group was significantly less severe than that in the calcium hydroxide group (P < 0.05). After the 30-day observation period, the inflammatory reaction was slight in both groups, but specimens with dentin bridge formation in the self-etch adhesive group were significantly less common than those in the calcium hydroxide group (P < 0.05).

Evaluation of pulpal response of deciduous teeth after direct pulp capping with bioactive glass and mineral trioxide aggregate.

Aim:The aim of this study was to evaluate the pulpal response of primary teeth after direct pulp capping (DPC) with two biocompatible materials namely mineral trioxide aggregate (MTA) and bioactive glass (BAG).Settings and Design:This study was a randomized clinical trial.Materials and Methods:A total of 22 healthy primary canine teeth scheduled for extraction for orthodontic reasons were selected. The teeth were divided into two groups of 11 and underwent DPC. The exposure sites were randomly capped with MTA or BAG in the two groups. After 2 months, the teeth were extracted and prepared for histopathologic evaluation.Statistical Analysis:The data were analyzed using Fisher's exact test.Results:In the BAG group, inflammation was seen in three patients; internal resorption and abscess were not seen at all. In the MTA group, inflammation was seen in one patient and internal resorption and abscess were not seen in any patient. Fisher's exact test showed no significant difference between the two groups (P > 0.05). Dentinal bridge formation was noted in five patients in the BAG group and six patients in the MTA group. No significant difference was observed between the BAG and MTA groups using Chi-square analysis (P = 0.67).Conclusion:Based on the results of this study, MTA and BAG can be used for DPC of primary teeth.

Human Pulp Response to Direct Pulp Capping and Miniature Pulpotomy with MTA after Application of Topical Dexamethasone: A Randomized Clinical Trial.

Introduction:The aim of this randomized clinical trial was to compare the histologic pulp tissue response to one-step direct pulp capping (DPC) and miniature pulpotomy (MP) with mineral trioxide aggregate (MTA) after application of dexamethasone in healthy human premolars. Methods and Materials:Forty intact premolars from 10 orthodontic patients, were randomly chosen for DPC (n=20) or MP (n=20). In 10 teeth from each group, after exposure of the buccal pulp horn, topical dexamethasone was applied over the pulp. In all teeth the exposed/miniaturely resected pulp tissue was covered with MTA and cavities were restored with glass ionomer. Teeth vitality was evaluated during the next 7, 21, 42, and 60 days. Signs and/or symptoms of irreversible pulpitis or pulp necrosis were considered as failure. According to the orthodontic schedule, after 60 days the teeth were extracted and submitted for histological examination. The Kruskal-Wallis and Fisher’s exact tests were used for statistical analysis of the data (P=0.05). Results:Although dexamethasone specimens showed less inflammation, calcified bridge, pulpal blood vasculature, collagen fibers and granulation tissue formation were not significantly different between the groups (P>0.05). Conclusion:Topical dexamethasone did not hindered pulp healing but reduced the amount of underlying pulpal tissue inflammation after DPC and MP in healthy human premolars.

Influence of Soda Pulping Variables on Properties of Pineapple (Ananas comosusMerr.) Leaf Pulp and Paper Studied by Face-Centered Composite Experimental Design

Face-centered composite design (FCC) was used to study the effect of pulping variables: soda concentration (4-5 wt%), temperature (90–130°C), and pulping time (20–60 min) on the properties of pineapple leaf pulp and paper employing soda pulping. Studied pulp responses were screened yield and lignin content (kappa number). Paper properties, which include tensile index, burst index, and tear index, were also investigated. Effects of the pulping variables on the properties were statistically analyzed using Minitab 16. The optimum conditions to obtain the maximum tensile index were soda concentration of 4 wt%, pulping temperature of 105°C, and pulping time of 20 min. The predicted optimum conditions provided tensile index, burst index, tear index, screened yield, and kappa number of 44.13 kN·m/kg, 1.76 kPa·m2, 1.68 N·m2/kg, 21.29 wt%, and 28.12, respectively, and were experimentally confirmed.

Implant-Root Proximity and Pulp Vitality of the Tooth

Background: When dental implants are applied in partially edentulous patients, there is the risk of placing the implants in close proximity or in direct contact with the adjacent roots. In this situation assurance of pulp vitality of the adjacent tooth is neessary. Objectives: The current study aimed to assess pulp response of the tooth after root proximity with dental implant. Patients and Methods: After investigating 2800 records of patients, 31 implants in 29 patients were included in this study. A parallel peri-apical radiography was taken and pulp vitality tests (cold, heat and electrical pulp tests) were conducted for each patient. Results: Among the 31 assessed implants and the adjacent intact teeth, 13 implants had direct contact and 18 implants had proximity of less than 1 mm with the adjacent root. All of the teeth had positive (normal) pulp response to all tests. The most prevalent areas for proximity of implant-tooth were upper first premolar implants and upper canine teeth. The most approximation area was apical third of root of the teeth. Conclusions: Based on the clinical and radiographic examinations, implant-tooth approximation (less than 1 mm or direct contact) is not related to pulp vitality of the tooth. Further studies with larger sample sizes are necessary to confirm the results of the study.

Pulpal Responses to Direct Capping with Betamethasone/Gentamicin Cream and Mineral Trioxide Aggregate: Histologic and Micro–Computed Tomography Assessments

IntroductionThis clinical trial was conducted to evaluate the response of human dental pulp to direct capping with betamethasone/gentamicin (BG) cream and mineral trioxide aggregate (MTA). We hypothesized that the results of direct pulp capping with a topical BG combination would be similar to or better than those with MTA. MethodsThirty-six human first premolar teeth scheduled for orthodontic extraction were randomly divided into 4 groups: BG1 group (n = 9), BG cream with 2-week follow-up; BG2 group (n = 10), BG cream with 8-week follow-up; MTA1 group (n = 8), MTA with 2-week follow-up; and MTA2 group (n = 9), MTA with 8-week follow-up. Teeth were extracted and evaluated at respective time intervals. Micro–computed tomography scanning and histologic analyses were performed for all specimens. Pulp pathology (inflammation, pulp abscesses, and pulp necrosis) and reparative reaction (formation of dentin bridges) were recorded. ResultsBoth BG cream and MTA resulted in significantly better pulpal responses at 8 weeks than at 2 weeks. Dentin bridge formation was significantly thicker in the MTA group at 8 weeks than in any other group (P < .05). Inflammation was of the acute type in all groups; no statistically significant differences in the distribution of inflammatory cells were found among the groups. Pulpal abscesses and/or necrosis were observed more often in teeth capped with BG than with MTA. ConclusionsDirect pulp capping with both BG cream and MTA was associated with dentin bridge formation. MTA resulted in a significantly better pulpal response, with less inflammation and a thicker dentin bridge at 8 weeks.

Immune Cells and Molecular Networks in Experimentally Induced Pulpitis

Dental pulp is a dynamic tissue able to resist external irritation during tooth decay by using immunocompetent cells involved in innate and adaptive responses. To better understand the immune response of pulp toward gram-negative bacteria, we analyzed biological mediators and immunocompetent cells in rat incisor pulp experimentally inflamed by either lipopolysaccharide (LPS) or saline solution (phosphate-buffered saline [PBS]). Untreated teeth were used as control. Expression of pro- and anti-inflammatory cytokines, chemokine ligands, growth factors, and enzymes were evaluated at the transcript level, and the recruitment of the different leukocytes in pulp was measured by fluorescence-activated cell-sorting analysis after 3 h, 9 h, and 3 d post-PBS or post-LPS treatment. After 3 d, injured rat incisors showed pulp wound healing and production of reparative dentin in both LPS and PBS conditions, testifying to the reversible pulpitis status of this model. IL6, IL1-β, TNF-α, CCL2, CXCL1, CXCL2, MMP9, and iNOS gene expression were significantly upregulated after 3 h of LPS stimulation as compared with PBS. The immunoregulatory cytokine IL10 was also upregulated after 3 h, suggesting that LPS stimulates not only inflammation but also immunoregulation. Fluorescence-activated cell-sorting analysis revealed a significant, rapid, and transient increase in leukocyte levels 9 h after PBS and LPS stimulation. The quantity of dendritic cells was significantly upregulated with LPS versus PBS. Interestingly, we identified a myeloid-derived suppressor cell–enriched cell population in noninjured rodent incisor dental pulp. The percentage of this population, known to regulate immune response, was higher 9 h after inflammation triggered with PBS and LPS as compared with the control. Taken together, these data offer a better understanding of the mechanisms involved in the regulation of dental pulp immunity that may be elicited by gram-negative bacteria.

Response of exposed human pulp to application of a hemostatic agent and a self-etch adhesive

Objectives: The aim of this study was to investigate the human dental pulp response after use of a hemostatic agent (Ankaferd Blood Stopper [ABS]) and a self-etching adhesive system (Clearfil Protect Bond [CPB]) in direct pulp capping.Materials and methods: For the first aim, 21 non-carious human third molar teeth scheduled for extraction were selected. Class I cavities with pulp exposures were prepared. In group 1, bleeding was controlled with sterile cotton pellets and restored with calcium hydroxide (CH) + ZnOE cement + amalgam. In group 2, bleeding was controlled with sterile cotton pellets and restored with CPB and a composite resin. In group 3, bleeding was controlled with ABS and restored with CPB and a composite resin. The teeth were extracted after 90 days, formalin-fixed, and prepared for histological investigation. The pulp response was categorized using the following criteria: inflammatory response, soft tissue organization, reparative dentine formation, and bacterial staining. Data were submitted to statistical analysis, using nonparametric Kruskal–Wallis test.Results: In pulp response study, it showed no statistically significant differences between groups for all parameters (p > 0.05).Conclusions: The application of CPB and ABS in direct contact with the mechanically exposed pulp of healthy human teeth can lead to acceptable repair of the dentine–pulp complex, such as wound healing with tertiary dentine bridge formation.