Dentine sialoprotein and Collagen I expression after experimental pulp capping in humans using Emdogain®Gel

Comparative evaluation of treatment outcome of partial pulpotomy using different agents in permanent teeth-a randomized controlled trial

AIM

To compare and evaluate the clinical and radiographic performance, post-operative pain, and anti-inflammatory intake after partial pulpotomy (PP) with calcium hydroxide (CH), mineral trioxide aggregate (MTA), Biodentine (BD), and Emdogain (EMD) as pulp capping agents in mature permanent molars with definitive diagnosis of reversible pulpitis.

MATERIALS AND METHODS

As part of this prospective, randomized clinical trial with four parallel arms (CTRI Registration No.: CTRI/2020/11/029329 dated 24/11/2020), hundred and ten permanent molars with a clinical diagnosis of reversible pulpitis and normal apical tissues, from patients between the ages of 15 and 45 years, were recruited and randomly assigned to four groups-CH, MTA, BD, and EMD. Operative procedure was performed under local anesthesia and dental dam isolation. After carious pulpal exposure, 2 mm of superficially inflamed coronal pulp tissue was amputated and either of the four pulp capping materials was placed. The outcome assessment was carried out at 1, 3, 6, and 12 month(s) and was categorized as success (asymptomatic patients with PAI score = 1) or failure (symptomatic patients or PAI score > 1).

RESULTS

There was a significant difference in post-operative pain and anti-inflammatory medication intake after partial pulpotomy with Emdogain vis-à-vis other three capping agents. No difference in both clinical and radiographic performances was observed among the four capping agents.

CONCLUSION

Partial pulpotomy when performed following evidence-based guidelines results in high success rates regardless of capping agent employed. EMD can be considered a valid and suitable pulp capping agent in PP.

CLINICAL RELEVANCE

Meticulous examination and removal of superficially inflamed pulp under magnification and complete asepsis lead to successful pulpal healing regardless of capping agent employed.

Biocompatibility and Osteogenic Potential of Calcium Silicate-Based Cement Combined with Enamel Matrix Derivative: Effects on Human Bone Marrow-Derived Stem Cells

The characteristics of retrograde filling material are important factors that can affect the long-term success of apical microsurgery. Various calcium silicate-based cements (CSC) were introduced to overcome drawbacks of mineral trioxide aggregate (MTA), while Emdogain is known to be effective in the regeneration of periodontal tissues. The aim of this study is to evaluate the biocompatibility and osteogenic potential of various CSCs combined with Emdogain on human bone marrow-derived mesenchymal stem cells. Experimental groups were classified into eight groups depending on the material and the presence of Emdogain. In the cell-counting kit test, all experimental groups combined with Emdogain showed higher cell viability compared with those without Emdogain at days 1 and 2. In the wound-healing assay, cell migration increased significantly over time, with or without Emdogain. In the alkaline phosphatase assay, all groups treated with Emdogain showed higher activity compared with those without Emdogain at day 3 (p < 0.05). Using alizarin red S staining, all groups treated with Emdogain showed greater calcium nodule formation compared with those without Emdogain at days 7 and 14 (p < 0.05). In conclusion, using CSCs as retrograde filling materials and the application of additional Emdogain will increase bone regeneration and improve the prognosis of apical microsurgery.

Evaluating the potential of an amelogenin-derived peptide in tertiary dentin formation

Several novel biomaterials have been developed for dental pulp capping by inducing tertiary dentin formation. The aim of this study was to evaluate the effect of QP5, an amelogenin-based peptide, on the mineralization of dental pulp cells (DPCs) in vitro and in vivo. The cell viability of human DPCs (hDPCs) after treatment with QP5 was determined using the Cell Counting Kit-8 (CCK-8). Migration of hDPCs was assessed using scratch assays, and the pro-mineralization effect was determined using alkaline phosphatase (ALP) staining, alizarin red staining and the expression of mineralization-related genes and proteins. The results showed that QP5 had little effect on the cell viability, and significantly enhanced the migration capability of hDPCs. QP5 promoted the formation of mineralized nodules, and upregulated the activity of ALP, the expression of mRNA and proteins of mineralization-related genes. A pulp capping model in rats was generated to investigate the biological effect of QP5. The results of micro-computed tomography and haematoxylin and eosin staining indicated that the formation of tertiary dentin in QP5-capping groups was more prominent than that in the negative control group. These results indicated the potential of QP5 as a pulp therapy agent.

Immunohistochemical expression of non-collagenous extracellular matrix molecules involved in tertiary dentinogenesis following direct pulp capping: a systematic review

BACKGROUND

Extracellular matrix molecules (ECMM) expression during tertiary dentinogenesis provides useful information for regenerative applications and efficacy of pulp capping materials.

AIM

To identify and review the expression and roles of non-collagenous ECMM after successful direct pulp capping (DPC), following mechanical pulp exposures, via immunohistochemistry (IHC). The study addressed the question of where will successful DPC impact the IHC expression of these molecules.

DATA SOURCES

In vivo animal and human original clinical studies reporting on ECMM in relation to different follow-up periods were screened and evaluated via descriptive analysis. The electronic literature search was carried out in three databases (MEDLINE/PubMed, Web of Science, Scopus), followed by manual screening of relevant journals and cross-referencing, up to December 2018.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

Randomized and non-randomized controlled trials, conducted in humans and animals, were selected. Histological evidence for tertiary dentine formation was a prerequisite for IHC evaluation.

STUDY APPRAISAL AND SYNTHESIS METHODS

The methodological quality of the included articles was independently assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) and the Cochrane risk of bias tool (RoB 1), respectively.

RESULTS

From a total of 1534 identified studies, 18 were included. Thirteen papers evaluated animal subjects and five studies were carried out on humans. In animals and humans, fibronectin and tenascin expressions were detected in pulp and odontoblast-like cells (OLC); dentine sialoprotein was expressed in both soft and newly-formed mineralized tissue. In animals, bone sialoprotein was early expressed, in association with OLC and predentin; the immunoreactivity for dentine sialophosphoprotein and dentine matrix protein-1 was associated with the OLC and dentine bridge; osteopontin was expressed in OLC, predentine and reparative dentine. A considerable heterogeneity was found in the methodologies of the included studies, as well as interspecies variability of results in terms of time.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Within the limited scientific evidence, all non-collagenous ECMM expressions during tertiary dentinogenesis are active and related to soft and hard tissues. There is a shortage of human studies, and future research directions should focus more on them. PROSPERO Protocol: CRD42019121304.

Cytotoxicity and Bioactivity of Dental Pulp-Capping Agents towards Human Tooth-Pulp Cells: A Systematic Review of In-Vitro Studies and Meta-Analysis of Randomized and Controlled Clinical Trials

Background. In the era of biology-driven endodontics, vital pulp therapies are regaining popularity as a valid clinical option to postpone root-canal treatment. In this sense, many different materials are available in the market for pulp-capping purposes. Objectives. The main aim of this systematic review and meta-analysis was to examine literature regarding cytotoxicity and bioactivity of pulp-capping agents by exposure of human dental pulp cells of primary origin to these materials. A secondary objective was to evaluate the inflammatory reaction and reparative dentin-bridge formation induced by the different pulp-capping agents on human pulp tissue. Data sources. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 May 2020. No filters or language restrictions were initially applied. Two researchers independently selected the studies and extracted the data. Study selection included eligibility criteria, participants and interventions, study appraisal and synthesis methods. In vitro studies were included when human dental pulp cells of primary origin were (in) directly exposed to pulp-capping agents. Parallel or split-mouth randomized or controlled clinical trials (RCT or CCT) were selected to investigate the effects of different pulp-capping agents on the inflammation and reparative bridge-formation capacity of human pulp tissue. Data were synthesized via odds ratios (95% confidence interval) with fixed or random effects models, depending on the homogeneity of the studies. The relative risks (95% confidence interval) were presented for the sake of interpretation. Results. In total, 26 in vitro and 30 in vivo studies were included in the systematic review and meta-analysis, respectively. The qualitative analysis of in vitro data suggested that resin-free hydraulic calcium-silicate cements promote cell viability and bioactivity towards human dental pulp cells better than resin-based calcium-silicate cements, glass ionomers and calcium-hydroxide cements. The meta-analysis of the in vivo studies indicated that calcium-hydroxide powder/saline promotes reparative bridge formation better than the popular commercial resin-free calcium-silicate cement Pro-Root MTA (Dentsply-Sirona), although the difference was borderline non-significant (p = 0.06), and better than calcium-hydroxide cements (p < 0.0001). Moreover, resin-free pulp-capping agents fostered the formation of a complete reparative bridge better than resin-based materials (p < 0.001). On the other hand, no difference was found among the different materials tested regarding the inflammatory effect provoked at human pulp tissue. Conclusions. Calcium-hydroxide (CH) powder and Pro-Root MTA (Dentsply-Sirona) have shown excellent biocompatibility in vitro and in vivo when tested on human cells and teeth. Their use after many years of research and clinical experience seems safe and proven for vital pulp therapy in healthy individuals, given that an aseptic environment (rubber dam isolation) is provided. Although in vitro evidence suggests that most modern hydraulic calcium-silicate cements promote bioactivity when exposed to human dental pulp cells, care should be taken when these new materials are clinically applied in patients, as small changes in their composition might have big consequences on their clinical efficacy. Key findings (clinical significance). Pure calcium-hydroxide powder/saline and the commercial resin-free hydraulic calcium-silicate cement Pro-Root MTA (Dentsply-Sirona) are the best options to provide a complete reparative bridge upon vital pulp therapy. Systematic review registration number. PROSPERO registration number: CRD42020164374.

Characterization of Odontoblast-like Cell Phenotype and Reparative Dentin Formation In Vivo: A Comprehensive Literature Review

INTRODUCTION

The primary aim was to explore the criteria used in characterization of reparative cells and mineralized matrices formed after treatment of pulp exposures, and the sequence of relative events. The secondary aim was to evaluate whether the reparative events depend on the experimental model species, age, and therapeutic intervention.

METHODS

A literature search of databases using different combinations of the key words was undertaken. Data analysis was based only on studies having histological or histochemical assessment of the pulp tissue responses. The search yielded 86 studies, 47 capping material-based and 39 bioactive application-based experiments, which provided data on morphological or functional characterization of the mineralized matrices and the associated cells.

RESULTS

In 64% of capping material-based and 72% of bioactive application-based experiments, a 2-zone mineralized matrix formation (atubular followed by tubular) was detected, whereas characterization of odontoblastic differentiation is provided in only 25.5% and 46.1% of the studies, respectively. In 93.3% of the studies showing odontoblast-like cells, differentiated cells were in association with tubular mineralized matrix formation. Analyses further showed that cell- and matrix-related outcomes do not depend on experimental model species, age, and therapeutic intervention.

CONCLUSIONS

The evidence of the reviewed scientific literature is that dental pulp cells secrete a dentin-like matrix of tubular morphology in relation to primitive forms of atubular or osteotypic mineralized matrix. Furthermore, data analysis showed that dental pulp cells express in vivo the odontoblastic phenotype, and secrete matrix in a predentin-like pattern, regardless of the model species, age, and therapeutic intervention used.

The effect of dental pulp-capping materials on hard-tissue barrier formation: A systematic review and meta-analysis

BACKGROUND

The authors of this systematic review aimed to compare the effects of pulp-capping materials on hard-tissue barrier formation using histologic assessments.

TYPE OF STUDIES REVIEWED

The authors included randomized controlled trials and controlled clinical trials in humans, with vital therapies performed on healthy permanent teeth undergoing experimental mechanical pulp exposures. They searched electronically in the PubMed, Cochrane, Embase, and Summon databases and carried out a manual search. Twenty-seven full-text articles were eligible for inclusion in the systematic review. After data extraction, the authors performed 2 sets of meta-analyses with odds ratios (OR) and their 95% confidence intervals (CI) on 22 studies. Ten studies compared mineral trioxide aggregate (MTA) with calcium hydroxide (CH), and 12 compared bonding agents with CH. The authors assessed bias by means of Cochrane Collaboration's tool for assessing risk, funnel plots, and Harbord test.

RESULTS

The use of MTA was associated with a higher rate of hard-tissue barrier formation than CH. The OR comparing the 2 groups was 2.45 (95% CI, 1.39 to 4.29; P = .002). Use of bonding agents was associated with a lower rate of hard-tissue barrier formation than CH. The OR comparing the 2 groups was 0.02 (95% CI, 0.01 to 0.05; P < .001).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The results suggest that MTA and CH have positive effects on hard-tissue barrier formation. On the basis of the evidence, the authors conclude that MTA has better effects than CH regarding dental pulp protection in the capping of mechanical pulp exposures. Conversely, bonding agents are inferior to CH.

Direct Pulp Capping: What is the Most Effective Therapy?-Systematic Review and Meta-Analysis

INTRODUCTION

Direct pulp capping therapies use biomaterials to protect exposed tissues, inducing repair through the production of a mineralized barrier. The purpose of this study was to compare the effectiveness of biomaterials and techniques by means of a systematic review and meta-analysis.

METHODS

The PubMed, Cochrane, and Embase databases were used to search the literature published from January 1, 1980 until August 31, 2017. Studies that met inclusion criteria were screened by 2 authors individually. The meta-analysis was performed on mineral trioxide aggregate (MTA) cement vs calcium hydroxide cement, tricalcium silicate cement vs MTA cement, and adhesive systems vs CaOH cement and evaluated the success rate, inflammatory response, and dentin bridge formation.

RESULTS

Forty-six studies were included in the systematic review, while 22 studies were included in the meta-analysis. There was no significant heterogeneity between the studies. MTA cements showed a significantly higher success rate, in all parameters, compared with calcium hydroxide cements (odds ratio = 2.72; 95% confidence interval [CI] = 1.90-3.90; P = 0.000). However, when compared with the tricalcium silicate cements, there were no statistically significant differences (odds ratio = 1.18; 95% CI = 0.53-2.65; P = 0.672). Adhesive systems showed a significantly lower success rate, in all parameters, compared with calcium hydroxide cements (odds ratio = 0.062; 95% CI = 0.024-0.157; P = 0.000).

CONCLUSIONS

MTA cements have a higher success rate, with a lower inflammatory response and a more predictable hard dentin barrier formation than calcium hydroxide cements. However, there were no differences, in these parameters, when MTA cement was compared with tricalcium silicate cements. Dental adhesives systems showed the lowest success rates.

Efficacy of Enamel Matrix Derivative in Vital Pulp Therapy: A Review of Literature

Introduction:

Vital pulp therapy (VPT) aims to preserve the health and maintain life of the tooth pulp which has been compromised by caries, trauma or restorative procedures. Recently, enamel matrix derivative (EMD) has been introduced as a material for vital pulp therapy. The aim of this review is to critically analyze and summarize the available literature on EMD for VPT.

Methods and Materials:

Online databases (PubMED/MEDLINE, Google Scholar, ISI Web of Science, and Wiley-Online) were searched by using the following keywords in various combinations: Enamel Matrix Derivative, Emdogain, ‘Vital Pulp Therapy, ‘Apexogenisis’, Apexification, Pulp Capping, Endodontics, Dentine and Pulpotomy for studies indexed from January 1949 to April 2016. We used an English-limited search in Google.co.uk for the missing grey literature. All studies fulfilling the selection criteria were carefully reviewed for the focused question: “Does using EMD in VPT, compared with other materials, result in better clinical, radiographic and histological outcomes?”.

Results:

The primary search resulted in 18 articles of which, 14 articles (including 6 animal studies and 6 clinical trials and 2 case reports) met the inclusion criteria for this review and hence were included. The number of teeth tested in the animal studies ranged from 8 to 144 including pigs, rats and dogs teeth. A number of studies used EMD in the experimental group in comparison with calcium hydroxide, propylene glycol alginate (PGA) and MTA as a control. The observation period ranged from 1 to 2 months and 4 out of 6 animal trials reported more favorable outcomes with EMD while two studies reported comparable outcomes.

Conclusion:

Although EMD has potential for various applications in endodontics, studies conducted to date have failed to demonstrate any significant advantage of EMD over conventional VPT materials. Additionally, the 5-year and 10-year survival rate of EMD-treated teeth is not yet known. Hence, studies with a longer follow-up periods are required to deduce the long-term viability of teeth treated with EMD.

Demineralized bone matrix used for direct pulp capping in rats

Objectives

To evaluate the wound healing process following direct pulp capping with demineralized bone matrix (DBM) and calcium hydroxide (Ca(OH)₂).

Methods

Fifty 8-weeks-old SPF Wistar male rats were divided into two groups: one was the DBM treated group, and the other was the Ca(OH)₂ treated group. Pulpotomy was performed on the maxillary first molar of one side of each rat, and the another side was left as the blank control. Rats were sacrificed after each observation period (1, 3, 7, 14 and 28 days) and specimen slices were made. Hematoxylin-Eosin (HE) staining was used for observing the changes of pulp tissue, and immunohistochemical staining was used for observing the expression of reparative dentinogenesis-related factors runt transcription factor 2 (Runx2), type I collagen (COL I), osteocalcin (OCN) and dentin sialoprotein (DSP).

Results

Inflammatory cell infiltration (ICI) and pulp tissue disorganization (PTD) could be observed in both the DBM and Ca(OH)₂ groups at all observation periods. The DBM group showed slighter ICI on 1 and 28 days and milder PTD on 28 days, with a significant difference (P<0.05). Reparative dentin formation (RDF) could initially be observed on 14 days postoperatively, and the DBM group showed more regular and thinner RDF with significant differences on 14 and 28 days compared with the Ca(OH)₂ group (P<0.05). In both groups, the expression of Runx2, COL I, DSP and OCN were positive. Generally, the expression of these four factors in the DBM group was stronger than the Ca(OH)₂ group on the same observation periods.

Conclusions

DBM had the ability of inducing odontoblast differentiation and promoting dentinogenesis. DBM could initiate physiologic wound healing in pulp and had the ability to promote reparative dentin formation. Consequently, DBM may be an acceptable alternative for direct pulp capping.

Recombinant Human Plasminogen Activator Inhibitor-1 Accelerates Odontoblastic Differentiation of Human Stem Cells from Apical Papilla

Dental caries, the most prevalent oral disease in dental patients, involves the phases of demineralization and destruction of tooth hard tissues like enamel, dentin, and cementum. Dentin is a major component of the root and is also the innermost layer that protects the tooth nerve, exposure of which results in pain. In this study, we used human stem cells from apical papilla (hSCAP), which are early progenitor cells, to examine the effects of recombinant human plasminogen activator inhibitor-1 (rhPAI-1) on odontogenic differentiation in vitro and in vivo. We demonstrated that rhPAI-1 promoted the proliferation and odontogenic differentiation of hSCAP and increased the expression levels of odontoblast-associated markers. We also observed that rhPAI-1 upregulated the expression of Smad4, nuclear factor I-C (NFI-C), Runx2, and osterix (OSX) during odontogenic differentiation. Notably, transplantation of rhPAI-1-treated hSCAP effectively induced odontoblastic differentiation and dentinal formation. And the differentiated odontoblast-like cells showed numerous odontoblast processes inserted in dentin tubules and arranged collagen fibers. Furthermore, odontoblast-associated markers were more highly expressed in the rhPAI-1-induced differentiated odontoblast-like cells compared with the control group. These markers were also more highly expressed in the newly formed dentin-like tissue of the rhPAI-1-treated group compared with the control group. Consistent with our in vitro results, the expression levels of Smad4, NFI-C, and OSX were also increased in the rhPAI-1-treated group compared with the control group. Taken together, these results suggest that rhPAI-1 promotes odontoblast differentiation and dentin formation of hSCAP, and Smad4/NFI-C/OSX may play critical roles in the rhPAI-1-induced odontogenic differentiation. Thus, dental stem cells from apical papilla combined with rhPAI-1 could lead to dentin regeneration in clinical implications.

Dentinogenic Specificity in the Preclinical Evaluation of Vital Pulp Treatment Strategies: A Critical Review

Reviews on the clinical performance of vital pulp treatment strategies and capping materials repeatedly showed an insufficient grade of evidence concerning their therapeutic validity. The biological mechanisms underlying the regenerative potential of pulp-dentin complex have attracted much attention during the last two decades, since new pulp treatment modalities have been designed and tested at the preclinical level. It has been recognized that evaluation should be based on the specific ability of therapeutic interventions to signal recruitment and differentiation of odontoblast-like cells forming a matrix in a predentin-like pattern, rather than uncontrolled hard tissue deposition in a scar-like form. The aim of the present article was to critically review data from histological experimental studies on pulp capping, published during the last 7 decades. A comprehensive literature search covering the period from 1949 to 2015 was done using the Medline/Pubmed database. Inclusion of a study was dependent on having sufficient data regarding the type of capping material used and the unit of observation (human permanent tooth in vivo or animal permanent dentition; primary teeth were excluded). The post-operatively deposited matrix was categorized into three types: unspecified, osteotypic, or dentin-like matrix. One hundred fifty-two studies were included in the final evaluation. Data from the present systematic review have shown that only 30.2% of the 152 experimental histological pulp capping studies described the heterogenic nature of the hard tissue bridge formation, including osteotypic and tubular mineralized tissue. Structural characteristics of the new matrix and the associated formative cells were not provided by the remaining 106 studies. Analysis showed that more careful preclinical evaluation with emphasis on the evidence regarding the dentinogenic specificity of pulp therapies is required. It seems that selection of appropriate vital pulp treatment strategies and pulp capping materials would be further facilitated in terms of their therapeutic validity if international consensus could be reached on a select number of mandatory criteria for tissue-specific dentinogenic events.

Is hard tissue formation in the dental pulp after the death of the primary odontoblasts a regenerative or a reparative process?

OBJECTIVES

Conceptually, two types of tertiary dentine may be produced in response to caries and environmental irritations: "reactionary dentine" that is secreted by existing primary odontoblasts and "reparative dentine", formed after the death of the odontoblasts by proliferation and differentiation of progenitor cells into odontoblast-like cells. Because histologic evidence for tubular dentine generated by newly differentiated odontoblast-like cells is lacking in human teeth, the present study examined pulpal cellular changes associated with caries/restorations, in the presence or absence of pulpal exposures.

METHODS

Ninety-six extracted human teeth were histologically processed and serial sectioned for light microscopy: 65 contained untreated enamel/dentine caries; 20 were heavily restored and 11 had carious exposures managed by direct pulp-capping.

RESULTS

Sparsely distributed, irregularly arranged dentinal tubules were identified from the tertiary dentine formed in teeth with unexposed medium/deep caries and in restored teeth; those tubules were continuous with the tubules of secondary dentine; in some cases, tubules were absent. The palisade odontoblast layer was reduced to a single layer of flattened cells. In direct pulp-capping of pulp exposures, the defects were repaired by the deposition of an amorphous dystrophic calcified tissue that resembled pulp stones more than dentine, sometimes entrapping pulpal remnants. This atubular hard tissue was lined by fibroblasts and collagen fibrils.

CONCLUSIONS

Histological evidence from the present study indicates that reparative dentinogenesis cannot be considered as a regenerative process since the so-formed hard tissue lacks tubular features characteristic of genuine dentine. Rather, this process represents a repair response that produces calcified scar tissues by pulpal fibroblasts.

CLINICAL SIGNIFICANCE

Formation of hard tissue in the dental pulp after the death of the primary odontoblasts has often been regarded by clinicians as regeneration of dentine. If the objective of the clinical procedures involved is to induce healing, reduce dentine hypersensitivity, or minimise future bacteria exposure, such procedures may be regarded as clinical success. However, current clinical treatment procedures are not adept at regenerating physiological dentne because the tissues formed in the dental pulp are more likely the result of repair responses via the formation of calcified scar tissues.

Expression of Small Integrin-Binding LIgand N-linked Glycoproteins (SIBLINGs) in the reparative dentin of rat molars

AIM

To analyze the expression and distribution of Small Integrin-Binding LIgand N-linked Glycoproteins (SIBLINGs) in reparative dentin (RepD).

METHODOLOGY

Cavities on the mesial surfaces of rat molars were prepared to expose the pulp, and a calcium hydroxide agent was applied to cap the exposed pulp. The molars with pulp capping were extracted at postoperative 1, 2, and 4 weeks. The immunolocalization of four SIBLINGs, dentin matrix protein 1 (DMP1), dentin sialoprotein (DSP), bone sialoprotein (BSP), and osteopontin (OPN) in RepD, was analyzed in comparison with reactionary dentin (ReaD) and primary dentin (PD).

RESULTS

At two weeks after operation, the region of the exposed pulp formed a layer of reparative dentin bridge sealing the communication between the cavity and pulp chamber. Dentinal tubules in RepD were more irregular in shape and fewer in number than PD. At postoperative 2 and 4 weeks, RepD had lower levels of DMP1 and DSP than PD. BSP and OPN were present in RepD, but not in PD. RepD showed certain similarities to ReaD in the expression of SIBLINGs.

CONCLUSIONS

The reduced levels of DMP1 and DSP may be associated with the decreased number of dentinal tubules in RepD. The expression of BSP and OPN in RepD indicates that the odontoblast-like cells were attempting to produce a hard tissue at a very rapid pace. These findings suggest that in response to the surgical injury, the newly differentiated odontoblast-like cells altered their synthesis of the dentinogenesis-related proteins and produced a hard tissue that is an intermediate between dentin and bone.

Role of the extracellular signal-regulated kinase 1/2 pathway in driving tricalcium silicate-induced proliferation and biomineralization of human dental pulp cells in vitro

INTRODUCTION

The aim of this study was to investigate the role of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in regulating tricalcium silicate (C3S)-driven proliferation and biomineralization of human dental pulp cells (hDPCs) in vitro.

METHODS

Human DPCs were cultured in C3S-containing medium and compared with untreated controls. Cell viability was measured by the methyl-thiazol-tetrazolium assay. Biomineralization was assessed by staining calcium deposits on the extracellular matrix with von Kossa and alizarin red S stains. Phosphorylated ERK1/2 was evaluated by immunoblotting. The ERK1/2 inhibitor U0126 was used to assess the role of this pathway on stage of the cell cycle and mineralization-dependent gene expressions of hDPCs by using flow cytometry and real-time polymerase chain reaction, respectively. Data were analyzed by analysis of variance followed by the Student-Newman-Keuls post hoc test, with significance set at P < .05.

RESULTS

The viability and biomineralization of hDPCs were promoted by C3S extracts (P < .05). Phosphorylated ERK1/2 strongly appeared after hDPCs were cultured in the C3S extracts for 30 minutes. Moreover, inhibition of the ERK1/2 pathway in C3S-treated hDPCs decreased proliferation and the expression of mineralization-dependent genes, including collagen type I, dentin sialophosphoprotein, osteopontin, and osteocalcin (P < .05).

CONCLUSIONS

C3S stimulated the proliferation and biomineralization of hDPCs in vitro, with the ERK1/2 pathway playing a key role in the regulation of these effects.