Hard Tissue Formation Research Articles

Integrating Phosphate Enhances Biomineralization Effect of Methacrylate Cement in Vital Pulp Treatment with Improved Human Dental Pulp Stem Cells Stimulation.

Vital pulp treatment (VPT) is crucial for preserving the health and function of the tooth in cases where the pulp tissue remains vital despite exposure. Various materials are introduced for this purpose. However, challenges such as low strength, high solubility, and tooth discoloration persist. Methylmethacrylate-based cement (MC) offers excellent sealing ability, feasibility, and mechanical properties, making it a promising alternative for VPT. Phosphate-based glass (PBG) has the potential to promote hard tissue regeneration by releasing key inducers, phosphorus (P) and calcium (Ca), for reparative odontogenesis. This study investigates PBG-integrated MC (PIMC) by characterizing its properties, assessing human dental pulp stem cell activity related to initial inflammatory adaptation and odontogenic differentiation, and evaluating hard tissue formation using an in vivo dog pulpotomy model. Results indicate that a 5% PBG-integrated MC (5PIMC) maintains the physicochemical properties of MC. Furthermore, 5PIMC demonstrates cytocompatibility, excellent expression of osteo/odontogenic markers, and resistance to inflammatory markers, significantly outperforming MC. Enhanced hard tissue formation is observed in the dental pulp of mongrel dog teeth treated with 5PIMC. These findings suggest that 5PIMC could be an optimal and suitable material for reparative odontogenesis through VPT.

Single-cell RNA-seq analysis of rat molars reveals cell identity and driver genes associated with dental mesenchymal cell differentiation

BackgroundThe molecular mechanisms and signaling pathways involved in tooth morphogenesis have been the research focus in the fields of tooth and bone development. However, the cell population in molars at the late bell stage and the mechanisms of hard tissue formation and mineralization remain limited knowledge.ResultsHere, we used the rat mandibular first and second molars as models to perform single-cell RNA sequencing (scRNA-seq) analysis to investigate cell identity and driver genes related to dental mesenchymal cell differentiation during the late bell hard tissue formation stage. We identified seven main cell types and investigated the heterogeneity of mesenchymal cells. Subsequently, we identified novel cell marker genes, including Pclo in dental follicle cells, Wnt10a in pre-odontoblasts, Fst and Igfbp2 in periodontal ligament cells, and validated the expression of Igfbp3 in the apical pulp. The dynamic model revealed three differentiation trajectories within mesenchymal cells, originating from two types of dental follicle cells and apical pulp cells. Apical pulp cell differentiation is associated with the genes Ptn and Satb2, while dental follicle cell differentiation is associated with the genes Tnc, Vim, Slc26a7, and Fgfr1. Cluster-specific regulons were analyzed by pySCENIC. In addition, the odontogenic function of driver gene TNC was verified in the odontoblastic differentiation of human dental pulp stem cells. The expression of osteoclast differentiation factors was found to be increased in macrophages of the mandibular first molar.ConclusionsOur results revealed the cell heterogeneity of molars in the late bell stage and identified driver genes associated with dental mesenchymal cell differentiation. These findings provide potential targets for diagnosing dental hard tissue diseases and tooth regeneration.

Effects of Synthetic Toll-Like Receptor 9 Ligand Molecules on Pulpal Immunomodulatory Response and Repair after Injuries.

Synthetic oligodeoxynucleotides (ODNs) containing unmethylated cytosine-phosphate-guanine (CpG) motifs (CpG-ODNs) are ligand molecules for Toll-like receptor 9 (TLR9), which is expressed by odontoblasts in vitro and dental pulp cells. This study determined the effects of CpG-ODNs on pulpal immunomodulatory response and repair following injury. Briefly, the upper right first molars of three-week-old mice were extracted, immersed in Type A (D35) or B (K3) CpG-ODN solutions (0.1 or 0.8 mM) for 30 min, and then replanted. Pulpal healing and immunomodulatory activity were assessed by hematoxylin-eosin and AZAN staining, as well as immunohistochemistry. One week following the operation, inflammatory reactions occurred in all of the experimental groups; however, re-revascularization and newly formed hard tissue deposition were observed in the pulp chamber of all groups at week 2. A positive trend in the expression of immune cell markers was observed toward the CpG-ODN groups at 0.1 mM. Our data suggest that synthetic CpG-ODN solutions at low concentrations may evoke a long-lasting macrophage-TLR9-mediated pro-inflammatory, rather than anti-inflammatory, response in the dental pulp to modulate the repair process and hard tissue formation. Further studies are needed to determine the effects of current immunomodulatory agents in vitro and in vivo and develop treatment strategies for dental tissue regeneration.

Regenerative potential of mesoporous silica nanoparticles scaffold on dental pulp and root maturation in immature dog’s teeth: a histologic and radiographic study

ObjectiveTo evaluate histologically and radiographically the potential of dog’s immature roots with apical periodontitis to regenerate after regenerative endodontic treatment using mesoporous silica nanoparticles (MSNs) with/without bone morphogenic protein (BMP-2) as scaffolds.MethodsIn 4 mongrel dogs, 56 immature teeth with 96 roots were infected, resulting in necrotic pulps and periapical pathosis. According to the evaluation time (Group I = 30 days and Group II = 90 days), 90 roots were divided into two equal groups (45 roots each) and 6 roots used to replace any lost root during the procedure. The two main groups were further divided according to treatment protocol into 5 subgroups (9 roots each): blood clot (BC subgroup), mesoporous silica nanoparticles scaffold only (MSNs subgroup), mesoporous silica nanoparticles impregnated with BMP2 (MSNs + BMP2 subgroup), infected teeth without treatment (+ ve control subgroup) and normal untouched teeth (-ve control subgroup). All teeth surfaces were coated with Tincture iodine and calcium hydroxide was applied prior to treatment protocols. Then, teeth were restored with glass ionomer filling to seal the remaining part of the access cavity. Radiography evaluation of the increase in root length, root thickness and occurrence of apical closure were performed. Following the sacrifice of the two dogs at each time of evaluation, histopathological analysis was performed and included the inflammatory cells count, bone resorption, tissue ingrowth, deposition of hard tissue, and closure of the apical part. All data were statistically analyzed.ResultsCompared to BC subgroup, MSNs and MSNs + BMP-2 subgroups exhibited significant higher increase in root length and thickness as well as higher vital tissue in-growth and new hard tissue formation in group II (P < 0.05). MSNs + BMP-2 subgroup had significant higher increase in root length and thickness as well as significant lower inflammatory cell count than MSNs subgroup in both groups (P < 0.05). There were no significant differences between MSNs and MSNs + BMP-2 subgroups regarding new hard tissue formation in both groups and apical closure in group I (P > 0.05).ConclusionMSNs with/without BMP-2 scaffolds enabled the continuing growth of roots in immature teeth with necrotic pulps and periapical pathosis. Addition of BMP-2 to MSNs scaffold improved its outcome in regenerative endodontics.Clinical relevanceMSNs with/without BMP-2 scaffolds may alternate blood clot for regenerative endodontic treatment of immature teeth with necrotic pulps.

Histological response of inflamed pulp to hydraulic calcium silicate cements in direct pulp capping: Systematic review of pulpitis models.

This systematic review aimed to compare the histological response of inflamed pulpodentinal complex to the hydraulic calcium silicate cements in experimental animal models of pulpitis. Articles that evaluated the histological response of inflamed pulp to mineral trioxide aggregate (MTA) in comparison with other restorative materials were selected and analysed in detail. The risk of bias assessment was conducted using SYRCLE's RoB tool. The GRADEpro tool was used to determine the overall quality of evidence. Out of the 2947 retrieved articles from databases, five articles fulfilled the inclusion criteria. MTA induced significantly more hard tissue formation compared to calcium hydroxide. The use of pulp-capping material containing fluocinolone acetonide and ASP/PLGA-ASP/ACP/PLLA-PLGA composite membrane was comparable. This systematic review could not demonstrate enhanced efficiency of capping materials compared to MTA. Future well-conducted animal studies are warranted for demonstrating the hard tissue formation abilities of pulp-capping materials with convenient inflammatory conditions.

A triple growth factor strategy for optimizing bone augmentation in mice.

With dental implant treatment becoming the gold standard, the need for effective bone augmentation prior to implantation has grown. This study aims to evaluate a bone augmentation strategy integrating three key growth factors: bone morphogenetic protein-2 (BMP-2), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF). Collagen scaffolds incorporating BMP-2, IGF-1, or VEGF were fabricated and categorized into five groups based on their content: scaffold alone; BMP-2 alone (BMP-2); BMP-2 and IGF-1 (BI); BMP-2, IGF-1, and VEGF (BIV); and BMP-2 and IGF-1 with an earlier release of VEGF (BI + V). The prepared scaffolds were surgically implanted into the calvarias of C57BL/6JJcl mice, and hard tissue formation was assessed after 10 and 28 days through histological, tomographic, and biochemical analyses. The combination of BMP-2 and IGF-1 induced a greater volume of hard tissue augmentation compared with that of BMP-2 alone, regardless of VEGF supplementation, and these groups had increased levels of cartilage compared with others. The volume of hard tissue formation was greatest in the BIV group. In contrast, the BI + V group exhibited a hard tissue volume similar to that of the BI group. While VEGF and CD31 levels were highest in the BIV group at 10 days, there was no correlation at the same time point between hard tissue formation and the quantity of M2 macrophages. In conclusion, the simultaneous release of BMP-2, IGF-1, and VEGF proved to be effective in promoting bone augmentation.

Characterization of stromal calcifications in odontogenic keratocyst: a multicentric study.

Odontogenic keratocysts (OKCs) are locally aggressive cysts that exhibit typical histopathological features and have a propensity for recurrence. Though histological variations are observed in OKCs, hard tissue formation and metaplastic changes are rare, and the underlying pathogenesis is not well understood. This study aimed to characterize stromal calcifications andanalyze their association with odontogenic components in non-syndromic and syndrome-associated cases of OKCs. We analyzed 153 cases of OKCs from healthcare institutes in India and Japan. The epithelial and stromal features were evaluated, and the relationship of calcifications with odontogenic rests was determined. Immunohistochemistry for cytokeratin-19 and special stains including Masson Trichrome and Van Gieson, were used for identification of odontogenic rests and calcifications respectively. Stromal calcifications were observed in 29.41% OKCs. The calcification patterns included irregular dystrophic, dentinoid with linear or calcospherite-type mineralization, and psammoma calcifications. Psammoma and dentinoid calcifications were found in the proximity of cytokeratin-19-positive odontogenic rests or satellite cysts, whereas majority cases with dystrophic calcifications did not exhibit co-localization with stromal odontogenic components. Distinct patterns of calcifications were observed in OKCs. Calcifications found in proximity of the odontogenic rests were possibly indicative of an inductive or host-mediated response.

Inflammatory microenvironment of moderate pulpitis enhances the osteo-/odontogenic potential of dental pulp stem cells by autophagy.

This study investigated the effects of the inflammatory microenvironment of moderate pulpitis on biological properties of human dental pulp stem cells (DPSCs) and further explored the mechanism involved in osteo-/odontogenic induction of the inflammatory microenvironment. Healthy DPSCs (hDPSCs) and inflammatory DPSCs (iDPSCs) were isolated from human-impacted third molars free of caries and clinically diagnosed with moderate pulpitis, respectively. Healthy DPSCs were treated with lipopolysaccharides (LPS) to mimic iDPSCs invitro. The surface markers expressed on hDPSCs and iDPSCs were detected by flow cytometry. A CCK-8 assay was performed to determine cell proliferation. Flow cytometric analysis was used to evaluate cell apoptosis. The osteo-/odontogenic differentiation of DPSCs was evaluated by western blot, alkaline phosphatase staining, and Alizarin Red S staining. The functions of the genes of differentially expressed mRNAs of hDPSCs and iDPSCs were analysed using gene set enrichment analysis. Transmission electron microscopy and western blot were used to evaluate the autophagy changes of LPS-treated DPSCs. Compared with hDPSCs, iDPSCs showed no significant difference in proliferative capacity but had stronger osteo-/odontogenic potential. In addition, the mRNAs differentially expressed between iDPSCs and hDPSCs were considerably enriched in autophagosome formation and assembly-related molecules. Invitro mechanism studies further found that low concentrations of LPS could upregulate DPSC autophagy-related protein expression and autophagosome formation and promote its odontogenic/osteogenic differentiation, whereas the inhibition of DPSC autophagy led to the weakening of the odontogenic/osteogenic differentiation induced by LPS. This explorative study showed that DPSCs isolated from teeth with moderate pulpitis possessed higher osteo-/odontogenic differentiation capacity, and the mechanism involved was related to the inflammatory microenvironment-mediated autophagy of DPSCs. This helps to better understand the repair potential of inflamed dental pulp and provides the biological basis for pulp preservation and hard tissue formation in minimally invasive endodontics.

Edukasi “GEMINSU”(Gemar Minum Susu) untuk Kesehatan Gigi Mulut di Masa Pertumbuhan

The main problem of oral health in childhood is caries. Dental caries is caused by multifactorial factors including the host (tooth), substrate (food), microorganisms (bacteria) and time. Milk is a source of animal nutrition that is rich in calcium. Calcium plays an important role in the formation of dental hard tissue, making it more resistant to erosion and dental caries. By educating children at elementary school age to 'geminsu' love to drink milk can help children improve their ability to maintain oral health. This community service activity was carried out on students in grades 1-6 at SDN Lirboyo 1 Kediri City through several stages, namely pretest questionnaires, 'geminsu' education for oral health in infancy, posttest, door prize distribution, milk distribution, drinking milk together and group photos. The results of this community service showed that the percentage of knowledge about fond of drinking milk is important for oral health in infancy before education increased from 54% to 80%. The results of this service can be concluded that education on drinking milk can increase students' knowledge and awareness of the importance of milk for oral health during growth.

Radiographic Evaluation of Regenerative Endodontic Procedures and Apexification Treatments with the Assessment of External Root Resorption

IntroductionThis multicentered cohort study evaluated the radiographic outcomes of regenerative endodontic procedures (REPs) and apexification treatments (APEX) of immature teeth with endodontic disease. Materials and MethodsThis cohort study included a retrospective record review and prospective data collection of pediatric patients with teeth treated with REPs or APEX between 2005 and 2014. Data including the presence of a periapical lesion, external root resorption, obliteration, apical hard tissue, apical closure, intracanal calcifications, and radiographic root area (RRA) change based on measurements were collected/measured from radiographic images. Univariate and multivariate analyses were conducted. ResultsThe cohort included 190 subjects (204 teeth (92 REPs; 112 APEX)). The frequency of pretreatment periapical pathology was similar between cases in which the clinical treatment failed versus successful treatment cases. However, the frequency of pretreatment external root resorption was higher in failed cases than in successful cases (P = .007). The mean RRA change was greater than twenty percent in 21% of the REPs cases. In traumatized teeth, REPs resulted in less hard tissue formation than other endodontic disease etiologies measured by RRA (P = .001). Fifty-three percent of cases with ERR (16/30) showed signs of healing/arrest and were mostly treated with REPs (11/16). ConclusionsThe presence of ERR negatively affected the treatment outcome. There was significant variability in RRA change in REPs. Signs of healing/arrest of the resorptive lesion were radiographically visible in many cases treated with REPs.

Alternated activation with relaxation of periosteum stimulates bone modeling and remodeling

Gradual elevation of the periosteum from the original bone surface, based on the principle of distraction osteogenesis, induces endogenous hard and soft tissue formation. This study aimed to assess the impact of alternating protocols of activation with relaxation (periosteal pumping) on bone modeling and remodeling. One hundred and sixty-two adult male Wistar rats were used in this study. Four test groups with different pumping protocols were created based on the relaxation applied. Two control groups underwent an activation period without relaxation or only a single activation. One group was sham-operated. Periosteal pumping without period of activation induced gene expression in bone and bone remodeling, and following activation period enhanced bone modeling. Four test groups and control group with activation period equaled the values of bone modeling at the end-consolidation period, showing significant downregulation of Sost in the bone and periosteum compared to that in the sham group (p < 0.001 and p < 0.001, respectively). When all test groups were pooled together, plate elevation from the bony surface increased bone remodeling on day 45 of the observation period (p = 0.003). Furthermore, bone modeling was significantly affected by plate elevation on days 17 and 45 (p = 0.047 and p = 0.005, respectively) and by pumping protocol on day 31 (p = 0.042). Periosteal pumping was beneficial for increasing bone repair when the periosteum remained in contact with the underlaying bony surface during the manipulation period. Following periosteal elevation, periosteal pumping accelerated bone formation from the bony surface by the modeling process.

Effects of mechanical loading on matrix homeostasis and differentiation potential of periodontal ligament cells: A scoping review.

Various mechanical loadings, including mechanical stress, orthodontics forces, and masticatory force, affect the functions of periodontal ligament cells. Regulation of periodontal tissue destruction, formation, and differentiation functions are crucial processes for periodontal regeneration therapy. Numerous studies have reported that different types of mechanical loading play a role in maintaining periodontal tissue matrix homeostasis, and osteogenic differentiation of the periodontal ligament cells. This scoping review aims to evaluate the studies regarding the effects of various mechanical loadings on the secretion of extracellular matrix (ECM) components, regulation of the balance between formation and destruction of periodontal tissue matrix, osteogenic differentiation, and multiple differentiation functions of the periodontal ligament. An electronic search for this review has been conducted on two databases; MEDLINE via PubMed and SCOPUS. Study selection criteria included original research written in English that reported the effects of different mechanical loadings on matrix homeostasis and differentiation potential of periodontal ligament cells. The final 204 articles were mainly included in the present scoping review. Mechanical forces of the appropriate magnitude, duration, and pattern have a positive influence on the secretion of ECM components such as collagen, as well as regulate the secretion of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases. Additionally, these forces regulate a balance between osteoblastic and osteoclast differentiation. Conversely, incorrect mechanical loadings can lead to abnormal formation and destruction of both soft and hard tissue. This review provides additional insight into how mechanical loadings impact ECM homeostasis and multiple differentiation functions of periodontal ligament cells (PDLCs), thus making it valuable for regenerative periodontal treatment. In combination with advancing technologies, the utilization of ECM components, application of different aspects of mechanical force, and differentiation potential of PDLCs could bring potential benefits to future periodontal regeneration therapy.

Unraveling the structure, chemical composition, and conserved signaling in leech teeth

ABSTRACT Unlike vertebrates, the number of toothed taxa in invertebrates is very few, with leeches being the only tooth-bearing organisms in the phylum Annelida. Copious studies have been conducted regarding vertebrate teeth; however, studies regarding the structure and function of invertebrate teeth are limited. In this study, the tooth structure of leeches, specifically Hirudo nipponia and Haemadipsa rjukjuana, was revealed, which showed sharp and pointed teeth along the apex of three jaws. Understanding conserved signaling regulations among analogous organs is crucial for uncovering the underlying mechanisms during organogenesis. Therefore, to shed light on the evolutionary perspective of odontogenesis to some extent, we conducted de novo transcriptome analyses using embryonic mouse tooth germs, Hirudo teeth, and Helobdella proboscises to identify conserved signaling molecules involved in tooth development. The selection criteria were particularly based on the presence of tooth-related genes in mice, Hirudo teeth, and Helobdella proboscis, wherein 4113 genes were commonly expressed in all three specimens. Furthermore, the chemical nature of leech teeth was also examined via TEM-EDS to compare the chemical composition with vertebrate teeth. The examination of tissue-specific genetic information and chemical nature between leeches and mice revealed chemical similarities between leech and mice teeth, as well as conserved signaling molecules involved in tooth formation, including Ptpro, Prickle2, and Wnt16. Based on our findings, we propose that leech teeth express signaling molecules conserved in mice and these conserved tooth-specific signaling for dental hard tissue formation in mice would corresponds to the structural formation of the toothed jaw in leeches.

Negotiation of Calcified Canals.

The gradual formation of hard tissue along the root canal walls is a natural process associated with aging, typically progressing slowly over time. In reaction to tooth wear, operative procedures, vital pulp treatments, or regenerative endodontic procedures, hard tissue may also accumulate within the pulp canal space at a slow rate. In certain cases, such as dental trauma, autotransplantation, or orthodontic treatment, this deposition of hard tissue can accelerate unexpectedly, resulting in rapid narrowing or complete closure of the root canal space. This situation is called calcific metamorphosis (CM), root canal calcification, or pulp canal obliteration (PCO). Performing conventional endodontic therapy on severely calcified canals presents significant challenges and increases the risk of procedural accidents. Calcified canals introduce such complexity that dedicated negotiation concepts and specially designed instruments have been developed to deal with the challenge. This article seeks to review the existing methods for effectively navigating calcified canals and to introduce the buckling resistance activation test (BRAT) technique.

Lipids and Minerals, Interplay in Biomineralization: Nature's Alchemy.

The main focus of this article is the role of lipids in biomineralization. Much of the discussion on biomineralization focuses on proteins in these decades. Indeed, collagen and acidic noncollagenous proteins effectively serve as templates for mineralization. However, other macromolecules such as lipids and polysaccharides have received less attention despite their abundance at mineralization sites. The matrix vesicle (MV) theory is widely accepted as the induction of early mineralization. Although ion concentration within the vesicles has been discussed in the initial mineralization in this theory, the role of phospholipids that constitute the vesicle membrane has not been discussed much. Comprehensive considerations, including pathological mineralization, exist regardless of the localization of MVs, the involvement of bacteria in dental calculus formation, and biomineralization caused by marine organisms such as corals, suggesting that initial mineralization found in these biological conditions might be a common reaction relating to lipids. In contrast, despite the abundance of lipids, mineralization occurs only in the limited tissue within our body. In other words, gathering knowledge and creating a path to understanding about lipid-based mineralization is extremely important in proposing new bone disease treatment methods. This article describes how lipids influence nucleation, mineralization, and expansion during hard tissue formation.

Hard tissue formation in pulpotomized primary teeth in dogs with nanomaterials MCM-48 and MCM-48/hydroxyapatite: an in vivo animal study

BackgroundThis animal study sought to evaluate two novel nanomaterials for pulpotomy of primary teeth and assess the short-term pulpal response and hard tissue formation in dogs. The results were compared with mineral trioxide aggregate (MTA).MethodsThis in vivo animal study on dogs evaluated 48 primary premolar teeth of 4 mongrel female dogs the age of 6–8 weeks, randomly divided into four groups (n = 12). The teeth underwent complete pulpotomy under general anesthesia. The pulp tissue was capped with MCM-48, MCM-48/Hydroxyapatite (HA), MTA (positive control), and gutta-percha (negative control), and the teeth were restored with intermediate restorative material (IRM) paste and amalgam. After 4–6 weeks, the teeth were extracted and histologically analyzed to assess the pulpal response to the pulpotomy agent.ResultsThe data were analyzed using the Kruskal‒Wallis, Fisher’s exact, Spearman’s, and Mann‒Whitney tests. The four groups were not significantly different regarding the severity of inflammation (P = 0.53), extent of inflammation (P = 0.72), necrosis (P = 0.361), severity of edema (P = 0.52), extent of edema (P = 0.06), or connective tissue formation (P = 0.064). A significant correlation was noted between the severity and extent of inflammation (r = 0.954, P < 0.001). The four groups were significantly different regarding the frequency of bone formation (P = 0.012), extent of connective tissue formation (P = 0.047), severity of congestion (P = 0.02), and extent of congestion (P = 0.01). No bone formation was noted in the gutta-percha group. The type of newly formed bone was not significantly different among the three experimental groups (P = 0.320).ConclusionMCM-48 and MCM-48/HA are bioactive nanomaterials that may serve as alternatives for pulpotomy of primary teeth due to their ability to induce hard tissue formation. The MCM-48 and MCM-48/HA mesoporous silica nanomaterials have the potential to induce osteogenesis and tertiary (reparative) dentin formation.

Evaluation of biocompatibility and bioactive potential of Well-Root PT by comparison with ProRoot MTA and Biodentine

Background/purposeWell-Root PT is a novel bioceramic material developed to overcome limitations of conventional calcium silicate cements. The purpose of this study was to assess the biocompatibility and bioactivity of a premixed putty-type cement, Well-Root PT. Materials and methodsIdentical cylindrical samples were prepared from ProRoot MTA, Biodentine, and Well-Root PT. In vitro calcium weight volume and calcium ion release from the materials were evaluated with scanning electron microscopy and energy-dispersive spectroscopy and inductively coupled plasma-optical emission spectroscopy. An in vivo rat direct pulp capping model was implemented with the materials (n = 14 per material). The rats were sacrificed at 7 or 28 days. Hematoxylin and eosin and immunohistochemical analyses were performed. ResultsIn vitro calcium weight volume was 42.83 ± 8.82 % in ProRoot MTA, 47.05 ± 8.83 % in Biodentine, and 29.99 ± 4.94 % in Well-Root PT. Calcium ion releases from Well-Root PT after 7 and 28 days were similar with those from ProRoot MTA, but lower than those from Biodentine (P = 0.001 after 7 and 28 days equally). In an in vivo rat model, hematoxylin and eosin analysis showed no significant differences in inflammatory infiltration (P = 0.393) and hard tissue formation scores among the materials (P = 0.905). Also, both CD68 and DSPP expression showed similar results, with no significant differences among the materials (equally P = 0.874 for both markers). ConclusionWithin the limits of this study, Well-Root PT was comparable to ProRoot MTA and Biodentine in terms of biocompatibility and bioactivity.

Regulatory role of N-myc downregulated genes in amelogenesis in rats.

Cytodifferentiation of odontogenic cells, a late stage event in odontogenesis is based on gene regulation. However, studies on the identification of the involved genes are scarce. The present study aimed to search for molecules for the cytodifferentiation of ameloblastic cells in rats. Differential display-PCR revealed a differentially expressed gene between cap/early bell stage and hard tissue formation stage in molars. This gene was identified as N-myc Downregulated Gene 1 (Ndrg1), which is the first report in tooth development. Real time PCR and western blotting confirmed that the mRNA level of Ndrg1 was higher during enamel formation than the cap stage. Ndrg1 expression was upregulated in the early bell, crown, and root stages in a time-dependent manner. These patterns of expression were similar in Ndrg2, but Ndrg3 and Ndrg4 levels did not change during the developmental stages. Immunofluorescence revealed that strong immunoreactivity against Ndrg1 were detected in differentiated ameloblasts only, not inner enamel epithelium, odontoblasts and ameloblastic cells in defected enamel regions. Alkaline phosphatase and alizarin red s stains along with real time PCR, revealed that Ndrg1 and Ndrg2 were involved in cytodifferentiation and enamel matrix mineralization by selectively regulating amelogenin and ameloblastin genes in SF2 ameloblastic cells. These results suggest that Ndrg may play a crucial functional role in the cytodifferentiation of ameloblasts for amelogenesis.

Histological Evaluation of Pulpal Response and Dentin Bridge Formation After Direct Pulp Capping Using Recombinant Amelogenin and Mineral Trioxide Aggregate (MTA).

The purpose of the study was to compare and histologically investigate pulpal response and dentin bridge formation after direct pulp capping using recombinant amelogenin and mineral trioxide aggregate (MTA). Recombinant amelogenin protein and MTA were used as pulp capping materials in 120 teeth from eight mongrel dogs. Dogs were sacrificed at two different evaluation times. Regenerative changes were evaluated histologically. At two weeks, in contrast to the MTA group, most of the amelogenin group showed moderately formed hard tissue formation and the pulp tissue was completely filling the entire pulp chamber. These results were statistically significant. At two months, all the samples of the amelogenin group showed complete dentin bridge formation and the pulp chamber was filled entirely with tissue-mimicking the authentic pulp in all the specimens of the amelogenin group. These results were statistically significant. In conclusion, direct pulp capping by recombinant amelogenin protein resulted in significantly better regeneration of the dentin-pulp complex than MTA.

An animal study on the effectiveness of platelet-rich plasma as a direct pulp capping agent

Direct pulp capping (DPC) is a conservative approach for preserving tooth vitality without requiring more invasive procedures by enhancing pulp healing and mineralized tissue barrier formation. We investigated the effectiveness of Platelet Rich Plasma (PRP) vs. Mineral Trioxide Aggregate (MTA) as a DPC agent. Forty-two teeth from three mongrel dogs were divided into two equal groups. After three months, the animals were sacrificed to evaluate teeth radiographically using cone-beam computerized tomography, histopathologically, and real-time PCR for dentin sialophosphoprotein (DSPP), matrix extracellular phosphoglycoprotein (MEPE), and nestin (NES) mRNA expression. Radiographically, hard tissue formation was evident in both groups without significant differences (p = 0.440). Histopathologic findings confirmed the dentin bridge formation in both groups; however, such mineralized tissues were homogenous without cellular inclusions in the PRP group, while was osteodentin type in the MTA group. There was no significant difference in dentin bridge thickness between the PRP-capped and MTA-capped teeth (p = 0.732). The PRP group had significantly higher DSPP, MEPE, and NES mRNA gene expression than the MTA group (p < 0.05). In conclusion, PRP enables mineralized tissue formation following DPC similar to MTA, and could generate better cellular dentinogenic responses and restore dentin with homogenous architecture than MTA, making PRP a promising alternative DPC agent.