Reparative Dentin Formation Research Articles

The healing actions of propolis on direct pulp capping treatment : A review

Direct pulp capping is a technique used to seal the dental pulp which may become exposed due to mechanical and/or chemical factors as well as bacterial activity in order to stimulates reparative dentin formation. Wound healing on an exposed dental pulp needs an interactive process which requires highly organized activity of various cells, synthesizing cytokines, growth factors, and also collagen. Propolis or bee glue is a natural occuring resinous substance collected by honeybee, represents a popular remedy, well known for its broad spectrum of biological and pharmacological properties.The exact chemical composition of propolis varies depends on plants around the beehive. Generally, its contains a rich variety of potent terpene, benzoic, caffeic, cinnamic, aromatic aldehyde, phenolic acid, and high in flavonoid. Its also contains vitamin A, B complex, C, E and minerals. Many studies showed that propolis improves wound healing on an exposed dental pulp due to its several activities such as antioxidant, anti-inflammatory, antibacterial, and improved tissue regeneration. Therefore, the aim of this review is to discuss the use of propolis with emphasis on its healing actions on direct pulp capping treatment.

Reactionary and reparative dentin formation after pulp capping: Hydrogel vs. Dycal

Abstract Background After indirect capping, injured odontoblasts generate reactionary dentin, whereas after direct capping of a pulp exposure pulp, cells stimulate the formation of reparative dentin. The aim of this study was to evaluate and compare the effects of two direct capping agents on pulp tissue reactions: Hydrogel (a bovine serum albumin (BSA)/glutaraldehyde,) and Dycal (a calcium hydroxide-based capping agent). Methods In 6-week-old male Sprague–Dawley rats, occlusal cavities were drilled in the first maxillary molars, and the pulps were exposed. In one of the groups, 24 right molars were capped with Hydrogel (G1), whereas in the other group 24 M were capped with Dycal (G2). After 1 to 4 weeks, the rats were anaesthetized intraperitoneally (six rats per group) and perfused intracardiacally with 4 % paraformaldehyde fixative. Maxillary molar’s blocks were demineralized with a 4.13 % EDTA solution, embedded in paraffin, and the sections were histologically stained. Measurements of the thickness of reactionary dentin and area of inflammation were measured with ImageJ software. Results were compared with Kruskal Wallis and Mann Whitney U tests at p = 0.05. Results One week after Dycal capping, a statistically significant large number of aggregates of pulp cells enlightened pulpal inflammation compared to Hydrogel. At 2–3 weeks, reactionary dentin formation was increased at the periphery of the pulp chamber. After 4 weeks, a dentinal bridge sealed partially the pulp exposure, while tunnel defects persisting across reparative osteodentin. In contrast, 1 week after Hydrogel capping, inflammation was barely detectable. Hydrogel induced the massive apposition of reactionary dentin at the pulp periphery, and reparative dentin was developing within the pulp. The degradation of Hydrogel releases glutaraldehyde acting on pulp cells as a fixative and consequently favoring BSA bioactivity. Conclusion After Hydrogel capping, nemosis stimulates pulp mineralization, improving reactionary and reparative dentin formation. In contrast, the highly alkaline compound Dycal produced inflammation within the pulp. The differences between the two capping agents suggest that Hydrogel might present some clinical advantages over Dycal.

GaAlAs laser-induced pulp mineralization involves dentin matrix protein 1 and osteopontin expression.

GaAlAs lasers induce pulp mineralization by promoting reparative dentinogenesis. This study analyzed the expression of dentin matrix protein 1 (DMP1) and osteopontin in GaAlAs laser-irradiated rat molars, to examine the hypothesis that these proteins play a role in the laser-induced reparative dentinogenic process. The mesial surfaces of the upper first molars of 8-week-old Wistar rats were irradiated with a pulsed GaAlAs laser. After 1-14days, mRNA expression of DMP1 and osteopontin in the coronal pulp was analyzed using real-time PCR. DMP1, osteopontin, and heat shock protein 25 (HSP25) were immunolocalized at 1-21days. The pulp exhibited a degenerative zone in its mesial portion on days 1-3, and progressive formation of reparative dentin lined with HSP25-immunoreactive odontoblast-like cells, from day 7 onwards. DMP1 and osteopontin mRNA expression were significantly upregulated on days 1-7 and 3-7, respectively. From day 7 onwards, DMP1 and osteopontin immunoreactivity colocalized along the boundary between the primary and reparative dentin. GaAlAs laser irradiation of rat molars induced upregulated DMP1 and osteopontin mRNA expression in the coronal pulp, followed by the formation of reparative dentin and the colocalization of DMP1 and osteopontin immunoreactivity at the site at which this tissue first appeared.

JAB1 accelerates odontogenic differentiation of dental pulp stem cells.

Jun activation domain-binding protein 1 (JAB1) is a multifunctional protein that participates in the control of cell proliferation and the stability of multiple proteins. JAB1 regulates several key proteins, and thereby produces varied effects on cell cycle progression, genome stability and cell survival. Some studies have shown that the loss of JAB1 in osteochondral progenitor cells severely impairs embryonic limb development in mice. However, the biological significance of JAB1 activity in the odontogenic differentiation of dental pulp stem cells (DPSCs) remains unclear. This study aimed to determine the role of JAB1, a key player in tooth development, in reparative dentin formation, especially odontogenic differentiation. We found that increased expression of JAB1 promoted odontogenic differentiation of DPSCs via Wnt/β-catenin signaling. The role of JAB1 in the odontogenic differentiation of DPSCs was further confirmed by knocking down JAB1. Our findings provide novel insights on odontogenic differentiation of DPSCs.

Dentinal Tubules of Attrited, Abraded and Eroded Teeth- A Comparative Evaluation of Scanning Electron and Light Microscope

im: The aim was to study the ultrastructure of dentin exposed by attrition, abrasion and erosion separately and in combination and to visualize the lesions using scanning electron microscope and thereby establish a superior basis for evaluating dentinal changes at the ultra-structural level and to correlate the findings with changes seen at the light microscopic level. Study Design: Tooth wear is often multifactorial. Loss and excessive wear of hard dental tissues is a permanent problem of the dentition, especially in present era, encompassing almost all age groups. In this study 40 extracted teeth were used. Four groups were made and comparison was made between light microscope and scanning. electron microscopic findings. Place and Duration of Study: Department of oral and maxillofacial pathology, career post graduate institute of dental sciences, lucknow, (U.P.), India. Methodology: Forty extracted permanent teeth (10 attrited, 10 abraded, 10 eroded and 10 normal premolars and molars) were sampled divided into four groups. After debridement and fixation in 10% formalin for 24-48 hours, the teeth were fractured along their longitudinal axes. Two halves of the teeth were studied under scanning electron and light microscope. The dentinal changes secondary to attrition, abrasion and erosion such as dead tracts, dentinal sclerosis and reparative dentin formation seen under light microscopy, were correlated with the ultra-structural findings. The data so obtained were tabulated and statistically analyzed. Results: The light microscopic finding of 4 randomly selected teeth, showed frequency of tertiary dentin significantly more than dead tracts and dentinal sclerosis was absent, from each group. 10 samples scanned with electron microscope showed the tubular surface/margins smooth, tubular surface/margins rough and presence of crystals was highly significant (p<0.001) whereas peritubular dentin and intertubular dentin, was not significant (p>0.05) in each group. Similarly, mean density of dentinal tubules of normal group was the highest followed by abraded, attrited and eroded the least. The percentage of affected dentinal tubules was most in eroded & least in attrited teeth. Conclusion: The scanning electron microscope is a powerful magnification tool which offers extremely high resolution. In the present study, scanning electron microscopic image complements the information available from the light microscope about the dentinal changes in abraded, attrited and eroded teeth.

ラット抜歯窩の創傷治癒を目的とした炭酸ガスレーザー照射による隣接歯への影響

The utility of laser irradiation has been demonstrated in basic and clinical studies, albeit with an associated risk of tissue damage. We previously tested a combination of high reactive level laser therapy (HLLT) and low reactive level laser therapy (LLLT) using a carbon dioxide laser for enhanced post-extraction wound healing and observed irreversible changes in the pulps of the teeth adjacent to the extracted tooth. The aim of this study was to elucidate the histopathological changes in the pulps of teeth adjacent to the site of carbon dioxide laser irradiation performed to achieve enhanced wound healing after tooth extraction; here we report the significance of care for the adjacent tissues in laser irradiation therapy. A total of 20 male Wistar rats (5 weeks old) were divided into an irradiation group that received HLLT combined with LLLT and a non-irradiation (control) group that did not. A tooth socket model was prepared by extracting the maxillary left first molar. HLLT and LLLT were respectively performed immediately and 1 day after tooth extraction. Laser-stimulated tissues surrounding the extracted tooth, namely, the socket and adjacent teeth, were collected from each rat both 7 and 10 days after tooth extraction. The obtained specimens were fixed in 4% paraformaldehyde, decalcified in 10% ethylenediaminetetraacetic solution, and then embedded in paraffin. Serial sagittal sections were stained with hematoxylin and eosin for histopathological examination. Laser-induced injuries, such as enamel ablation and dentin carbonization, were absent 7 days after tooth extraction in both groups. Formation of reparative dentin was observed along the rim of the laser-irradiated area in the dental pulps in the irradiation group but not the control group. Both groups showed no signs of inflammation in pulp tissues. Enamel and dentin injuries were not observed in either group at 10 days after tooth extraction, similar to the findings at 7 days after tooth extraction. Formation of reparative dentin was much more prominent at 10 days after tooth extraction than at 7 days in the irradiation group. In contrast, no formation of reparative dentin was observed at either time point in the control group. These results show that carbon dioxide laser irradiation induces the formation of reparative dentin in the pulps of teeth adjacent to the extracted tooth socket. In sum, carbon dioxide laser irradiation at the low reactive level appears to induce irreversible changes in the tissues surrounding the laser treatment site.

Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial.

Aim:To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT) using mineral trioxide aggregate (MTA) and light cured calcium silicate (TheraCal) in primary molars over a period of 6 months.Materials and Methods:A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4–7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digitalized radiograph at baseline, 3 months and 6 months using CorelDRAW X3 software.Results:Statistical analysis using an independent t-test for intragroup and intergroup comparison showed a significant increase in dentin thickness in both the MTA and TheraCal group (intragroup comparison [P < 0.05]). However, intergroup comparison between MTA and TheraCal showed no statistical difference in reparative dentin formation (P > 0.05).Conclusion:Clinically and radiographically, both MTA and TheraCal are good IPT materials. The better handling characteristics and comparable reparative dentin-forming ability of TheraCal make this material an alternative to MTA in pediatric restorative procedures.

Effect of an experimental adhesive resin containing multi-ion releasing fillers on direct pulp-capping.

The purpose of this study was to evaluate pulpal healing and reparative dentin formation after 14 and 28 days in exposed rat pulp directly capped with an experimentally developed all-in-one adhesive containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler. The four experimental groups and the control group were compared using the Kruskal-Wallis test, followed by the Steel-Dwass post-hoc test to compare the histopathological score. The Mann-Whitney U test was used to compare the histopathological score at 14 and 28 days for each observation item. All experimental adhesives containing S-PRG fillers developed for direct pulp capping showed no pulpal inflammation. After 14 days, the experimental adhesives containing S-PRG fillers and the control group formed tertiary dentin around the exposed pulp. After 28 days, the experimental adhesives containing 13 and 27 wt% of S-PRG fillers formed dentin bridge equal to the control.

Current status of direct pulp-capping materials for permanent teeth.

Direct pulp-capping is a method for treating exposed vital pulp with dental material to facilitate the formation of reparative dentin and to maintain vital pulp. Two types of pulp-capping materials, calcium hydroxide and mineral trioxide aggregate, have been most commonly used in clinics, and an adhesive resin has been considered a promising capping material. However, until now, there has been no comprehensive review of these materials. Therefore, in this paper, the composition, working mechanisms and clinical outcome of these types of pulp-capping materials are reviewed.

Evaluation of reparative dentin formation of ProRoot MTA, Biodentine and BioAggregate using micro-CT and immunohistochemistry

ObjectivesThe purpose of this study was to assess the ability of two new calcium silicate-based pulp-capping materials (Biodentine and BioAggregate) to induce healing in a rat pulp injury model and to compare them with mineral trioxide aggregate (MTA).Materials and MethodsEighteen rats were anesthetized, cavities were prepared and the pulp was capped with either of ProRoot MTA, Biodentine, or BioAggregate. The specimens were scanned using a high-resolution micro-computed tomography (micro-CT) system and were prepared and evaluated histologically and immunohistochemically using dentin sialoprotein (DSP).ResultsOn micro-CT analysis, the ProRoot MTA and Biodentine groups showed significantly thicker hard tissue formation (p < 0.05). On H&E staining, ProRoot MTA showed complete dentin bridge formation with normal pulpal histology. In the Biodentine and BioAggregate groups, a thick, homogeneous hard tissue barrier was observed. The ProRoot MTA specimens showed strong immunopositive reaction for DSP.ConclusionsOur results suggest that calcium silicate-based pulp-capping materials induce favorable effects on reparative processes during vital pulp therapy and that both Biodentine and BioAggregate could be considered as alternatives to ProRoot MTA.

LncRNA DANCR suppresses odontoblast-like differentiation of human dental pulp cells by inhibiting wnt/β-catenin pathway.

Long noncoding RNAs (lncRNAs) have recently emerged as an important class of regulatory molecules in diverse biological processes, although lncRNA involvement in the odontoblast-like differentiation of human dental pulp cells (hDPCs) is poorly understood. We investigate the expression of lncRNAs in this differentiation and explore their underlying role and the involved mechanism. Integrated comparative lncRNA microarray profiling was used to examine lncRNA expression during this differentiation. The differential expression of lncRNAs was validated by quantitative real-time reverse transcription plus the polymerase chain reaction. Differential lncRNA overexpression was performed with an adenoviral vector and the role and mechanism was then investigated in odontoblast-like differentiation. We identified 139 differentially expressed lncRNAs during this differentiation. Among them, five lncRNAs differentially expressed in microarray analysis were validated. Notably, lncRNA DANCR expression was significantly downregulated during hDPC differentiation to odontoblast-like cells in a time-dependent manner. Moreover, lncRNA DANCR overexpression blocked mineralized nodule formation and the expression of DSPP and DMP-1 in hDPCs after 14 days of odontogenic induction. Importantly, the upregulation of DANCR significantly decreased the expression levels of p-GSK-3β and β-catenin expression indicating that lncRNA DANCR can inhibit the activation of the Wnt/β-catenin signal pathway during the odontoblast-like differentiation of hDPCs. Thus, the modulation of Wnt/β-catenin signaling by lncRNA DANCR represents a potential therapeutic option for reparative dentin formation and regenerative endodontics.

Histological evaluation of direct pulp capping of rat pulp with experimentally developed low-viscosity adhesives containing reparative dentin-promoting agents

ObjectivesThis study examines the wound healing process in exposed rat pulp when capped with experimental adhesive resin systems. MethodsExperimental adhesive resin system for direct pulp capping was composed of primer-I (PI), -II (PII), and -III (PIII) and an experimental bonding agent (EBA). PI was Clearfil® SE Bond®/Primer (CSP) containing 5.0wt% CaCl2, PII was PI containing 10wt% nanofiller (Aerosil® 380), and PIII was CSP containing 5.0wt% of compounds of equal moles of synthetic peptides (pA and pB) derived from dentin matrix protein 1. EBA was Clearfil® SE Bond®/Bond (CSB) containing 10wt% hydroxyapatite powders. Three experimental groups were designed. PI was assigned to experimental Groups 1 and 3. PII was assigned to experimental Groups 2 and 3. PIII and EBA were assigned to all experimental adhesive groups. Control teeth were capped with calcium hydroxide preparation (Dycal®), and CSP and CSB were applied to the cavity. The rats were sacrificed after each observation period (14, 28, 56, and 112 days). The following parameters were evaluated: pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation (RDF), and bacterial penetration. ResultsThere were no significant differences among all the groups for all parameters and all observation periods (p>0.05, Kruskal–Wallis test). All groups showed initial RDF at 14 days postoperatively and extensive RDF until 112 days postoperatively. Groups 2 and 3 demonstrated higher quantity of mineralized dentin bridge formation compared with Group 1. ConclusionsAddition of nanofillers to the primer was effective in promoting high-density RDF. Clinical significanceExperimentally developed adhesive resin systems induce the exposed pulp to produce almost the same quantity of reparative dentin as calcium hydroxide. However, we need further studies to elucidate whether the same results could be obtained in humans.

Effects of human vascular endothelial growth factor on reparative dentin formation

It is a challenge for dentists to save dental pulp in patients with pulp disease without resorting to root canal therapy. Formation of tertiary dentin to maintain pulp vitality is a key odontoblast response to dental pulp injury. Vascular endothelial growth factor (VEGF) is the most potent angiogenic and vasculogenic factor involved in tertiary dentin formation. It was hypothesized that VEGF may be used to treat pulp diseases such as pulpitis. To explore this hypothesis, the first step was to assess whether VEGF affects dental pulp cells to promote reparative dentin formation. In the current study, an AdCMV-hVEGF vector was constructed to deliver hVEGF into dental pulp cells of exfoliated deciduous teeth (hDPCs) in vitro and dental pulp cells in a rat model in vivo. The collected data clearly demonstrated that hVEGF increased alkaline phosphatase and mineralization by enzymatic activity. RT-qPCR data demonstrated that hVEGF significantly increased the expression levels of genes commonly involved in osteogenesis/odontogenesis. Data from the in vivo assays indicated that hVEGF enhanced pulp cell proliferation and neovascularization, and markedly increased formation of reparative dentin in dental pulp. The in vitro and in vivo data suggest that hVEGF may have potential clinical applications, thus may aid in the development of novel treatment strategies for dental pulpitis.

The Role of ORAI1 in the Odontogenic Differentiation of Human Dental Pulp Stem Cells

Pulp capping, or placing dental materials directly onto the vital pulp tissues of affected teeth, is a dental procedure that aims to regenerate reparative dentin. Several pulp capping materials are clinically being used, and calcium ion (Ca2+) released from these materials is known to mediate reparative dentin formation. ORAI1 is an essential pore subunit of store-operated Ca2+ entry (SOCE), which is a major Ca2+ influx pathway in most nonexcitable cells. Here, we evaluated the role of ORAI1 in mediating the odontogenic differentiation and mineralization of dental pulp stem cells (DPSCs). During the odontogenic differentiation of DPSCs, the expression of ORAI1 increased in a time-dependent manner. DPSCs knocked down with ORAI1 shRNA (DPSC/ORAI1sh) or overexpressed with dominant negative mutant ORAI1E106Q (DPSC/E106Q) exhibited the inhibition of Ca2+ influx and suppression of odontogenic differentiation and mineralization as demonstrated by alkaline phosphatase (ALP) activity/staining as well as alizarin red S staining when compared with DPSCs of their respective control groups (DPSC/CTLsh and DPSC/CTL). The gene expression for odontogenic differentiation markers such as osteocalcin, bone sialoprotein, and dentin matrix protein 1 (DMP1) was also suppressed. When DPSC/CTL or DPSC/E106Q cells were subcutaneously transplanted into nude mice, DPSC/CTL cells induced mineralized tissue formation with significant increases in ALP and DMP1 staining in vivo, whereas DPSC/E106Q cells did not. Collectively, our data showed that ORAI1 plays critical roles in the odontogenic differentiation and mineralization of DPSCs by regulating Ca2+ influx and that ORAI1 may be a therapeutic target to enhance reparative dentin formation.

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.

Clinical, radiographic, and histologic analysis of the effects of acemannan used in direct pulp capping of human primary teeth: short-term outcomes.

Acemannan has been previously reported as a direct pulp-capping agent in animal study. This natural material demonstrated its biocompatibility and enhanced reparative dentin formation. The objective of this study was to investigate the action of acemannan as a direct pulp-capping material in human primary teeth with deep caries. Forty-two deeply carious mandibular primary molars from 37 children, aged 7-11years old diagnosed with reversible pulpitis were studied. After completely removing the infected dentine, teeth with a pinpoint pulpal exposure were randomly divided into two treatment groups: acemannan or calcium hydroxide. A glass-ionomer cement base was applied to all teeth prior to restoration with stainless steel crowns. Clinical and radiographic evaluation was performed 6months post-treatment. The teeth due to exfoliate were extracted and histopathologically evaluated for inflammation, dentine bridge formation, and soft tissue organization. At 6months, the overall clinical and radiographic success rates of direct pulp capping with acemannan and calcium hydroxide at 6months were 72.73 and 70.0%, respectively. The histopathological results indicated that the acemannan-treated group had significantly better histopathological responses compared with the calcium hydroxide-treated group (p<0.05). These data suggest acemannan offers a valuable alternative biomaterial for vital pulp therapy in primary teeth.

Relationship between length variations in Ser/Asp-rich repeats in phosphophoryn and in vitro precipitation of calcium phosphate

ObjectivePhosphophoryn (PP) is generated from the proteolytic cleavage of dentin sialophosphoprotein (DSPP). PP which contains tandem serine/asparatic acid rich repeats (SDrr) is known to enhance dentin mineralization. The nucleotide sequences coding SDrr are identified in the DSPP genes of toothed animals and the length variations of SDrr between intra- and inter-species have been reported. However, it remains unknown about the relationship between the length variations in SDrr and the functions of PP in matrix mineralization. DesignBy utilizing a mammalian expression system, we generated several recombinant PP proteins (rPP) containing SDrr of different lengths and analyzed their effects on the precipitation of calcium phosphate with an in vitro gel diffusion system. ResultsrPP-Δ37.6 SDrr and rPP-Δ63.5 SDrr, which possessed shortened SDrr that accounted for 62.4 and 36.5% the length of SDrr in full-length rPP (rPP-full), respectively, induced the precipitation of calcium phosphate similar to that of rPP-full at the same molar concentration, whereas rPP-ΔSDrr, in which SDrr were flipped, did not. Furthermore, rPP-Δ63.5 SDrr significantly increased the accumulation of calcium compared with rPP-full at adjusted concentrations so that the same amounts of SDrr were embedded. The results of an ELISA analysis indicated that the amounts of rPP-Δ37.6 SDrr and rPP-Δ63.5 SDrr secreted from transfected cells were 5.2- and 7.1-fold greater than that of rPP-full, respectively. ConclusionsThe generated rPP-Δ63.5 SDrr which can be substituted for rPP-full may be a candidate for a therapeutic molecule to facilitate hard tissue generation such as reparative dentin formation.

Evaluation of direct pulp capping with a synthetic chalcone: a preliminary histological study.

Objective: The aim of this study is to evaluate the action of the synthetic chalcone 1-phenyl-3-(4-chlorophenyl)-2-propen-1-one to induce pulp healing in rats. Material and Methods: Sixty lower first molars of male Wistar rats were divided into 3 groups (n= 20): control (no treatment); calcium hydroxide and chalcone . After relative isolation, the cavities were prepared using a sterile low-speed ¼ round dental bur. After controlling the hemorrhaging, all the pulp exposures were capped with the capping material, by groups. The cavities were sealed with glass ionomer cement and the repair process was assessed at 21 days of procedure. The data were statistically analyzed using the Fisher exact test (p<0.05). Results: Moderate inflammation was observed in all the experimental groups and significant (p<0.05) reparative dentin (tertiary) formation in the calcium hydroxide and chalcone groups. The chalcone group showed dentinal tubules and a low number of cellular inclusions (p<0.05). Conclusion: The chalcone used in this study indicates potential as an inducer of reparative dentine (tertiary) in a rat model.

Bone morphogenetic protein 2-induced human dental pulp cell differentiation involves p38 mitogen-activated protein kinase-activated canonical WNT pathway.

Both bone morphogenetic protein 2 (BMP2) and the wingless-type MMTV integration site (WNT)/β-catenin signalling pathway play important roles in odontoblast differentiation and dentinogenesis. Cross-talk between BMP2 and WNT/β-catenin in osteoblast differentiation and bone formation has been identified. However, the roles and mechanisms of the canonical WNT pathway in the regulation of BMP2 in dental pulp injury and repair remain largely unknown. Here, we demonstrate that BMP2 promotes the differentiation of human dental pulp cells (HDPCs) by activating WNT/β-catenin signalling, which is further mediated by p38 mitogen-activated protein kinase (MAPK) in vitro. BMP2 stimulation upregulated the expression of β-catenin in HDPCs, which was abolished by SB203580 but not by Noggin or LDN193189. Furthermore, BMP2 enhanced cell differentiation, which was not fully inhibited by Noggin or LDN193189. Instead, SB203580 partially blocked BMP2-induced β-catenin expression and cell differentiation. Taken together, these data suggest a possible mechanism by which the elevation of β-catenin resulting from BMP2 stimulation is mediated by the p38 MAPK pathway, which sheds light on the molecular mechanisms of BMP2-mediated pulp reparative dentin formation.

Tomographic Evaluation of Reparative Dentin Formation after Direct Pulp Capping with Ca(OH)2, MTA, Biodentine, and Dentin Bonding System in Human Teeth

IntroductionNew materials can increase the efficiency of pulp capping through the formation of a complete reparative dentin bridge with no toxic effects. The present study involved tomographic evaluations of reparative dentin bridge formation after direct pulp capping with calcium hydroxide, mineral trioxide aggregate (MTA), Biodentine (Septodont, Saint Maur des Fossés, France), and Single Bond Universal (3M ESPE, Seefeld, Germany) in human teeth. MethodsForty-four caries-free, intact, human third molars scheduled for extraction were subjected to mechanical pulp exposure and assigned to 1 of 4 experimental groups depending on the pulp capping agent used: calcium hydroxide, MTA, Biodentine, or Single Bond Universal. After 6 weeks, the teeth were extracted and processed for cone-beam computed tomographic imaging and histologic examination. Tomographic data, including the density and volume of formed reparative dentin bridges, were evaluated using a scoring system. ResultsThe reparative dentin formed in the calcium hydroxide, MTA, and Biodentine groups was significantly superior to that formed in the Single Bond Universal group in terms of thickness and volume. The dentin bridges in the Biodentine group showed the highest average and maximum volumes. The mean density of dentin bridges was the highest in the MTA group and the lowest in the Single Bond Universal group. ConclusionsThe volume of reparative dentin bridges formed after direct pulp capping is dependent on the material used. Biodentine and MTA resulted in the formation of bridges with a significantly higher average volume compared with Single Bond Universal, and cone-beam computed tomographic imaging allowed for the identification of the location of dentin bridges.