Dentinogenic Activity of Biodentine in Deep Cavities of Miniature Swine Teeth

Biodentine™ as a temporary filling in deep carious lesions in permanent teeth: a prospective observational 33-month follow-up study

PURPOSE

The study aimed to evaluate temporary fillings using Biodentine™ in asymptomatic deep carious lesions after 12, 24, and 36 months in school children from the remote village of Kerung, Nepal.

METHODS

From November 2018 to November 2019, 91 temporary fillings were placed using Biodentine™ (a hydraulic calcium silicate cement) in permanent molars with deep carious lesions of schoolchildren in the remote district of Kerung, Nepal. These restorations were performed after selective caries removal in a non-dental setting with hand instruments and cotton roll isolation, as electric motors and saliva ejection systems were unavailable. In total, 78 single-surface and 13 multi-surface fillings were placed. Clinical and radiographic follow-up periods encompassed 12, 21, and 33 months, respectively.

RESULTS

After 12 months, all single-surface fillings (100%) survived, whilst all multi-surface fillings were partially or entirely lost. The survival rate of single-surface restorations after 21 and 33 months was 67.6% and 50%, respectively. Radiographically, no pathology was observed.

CONCLUSION

This study showed that Biodentine could be used in deep carious lesions as a temporary filling in single-surface lesions for at least up to 1 year and in a substantial number of cases for up to 21 and 33 months.

Present status and future directions: Hydraulic materials for endodontic use

BACKGROUND

Hydraulic materials are used in Endodontics due to their hydration characteristics namely the formation of calcium hydroxide when mixing with water and also because of their hydraulic properties. These materials are presented in various consistencies and delivery methods. They are composed primarily of tricalcium and dicalcium silicate, and also include a radiopacifier, additives and an aqueous or a non-aqueous vehicle. Only materials whose primary reaction is with water can be classified as hydraulic.

OBJECTIVES

Review of the classification of hydraulic materials by Camilleri and the literature pertaining to specific uses of hydraulic cements in endodontics namely intra-coronal, intra-radicular and extra-radicular. Review of the literature on the material properties linked to specific uses providing the current status of these materials after which future trends and gaps in knowledge could be identified.

METHODS

The literature was reviewed using PUBMED, and for each clinical use, the in vitro properties such as physical, chemical, biological and antimicrobial characteristics and clinical data were extracted and evaluated.

RESULTS

A large number of publications were retrieved for each clinical use and these were grouped depending on the property type being investigated.

CONCLUSIONS

The hydraulic cements have made a difference in clinical outcomes. The main shortcoming is the poor testing methodologies employed which provide very limited information and also inhibits adequate clinical translation. Furthermore, the clinical protocols need to be updated to enable the materials to be employed effectively.

The Effect of Calcium-Silicate Cements on Reparative Dentinogenesis Following Direct Pulp Capping on Animal Models

Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges.

Role of connexin 43 in odontoblastic differentiation and structural maintenance in pulp damage repair

Dental pulp can initiate its damage repair after an injury of the pulp–dentin complex by rearrangement of odontoblasts and formation of newly differentiated odontoblast-like cells. Connexin 43 (Cx43) is one of the gap junction proteins that participates in multiple tissue repair processes. However, the role of Cx43 in the repair of the dental pulp remains unclear. This study aimed to determine the function of Cx43 in the odontoblast arrangement patterns and odontoblastic differentiation. Human teeth for in vitro experiments were acquired, and a pulp injury model in Sprague-Dawley rats was used for in vivo analysis. The odontoblast arrangement pattern and the expression of Cx43 and dentin sialophosphoprotein (DSPP) were assessed. To investigate the function of Cx43 in odontoblastic differentiation, we overexpressed or inhibited Cx43. The results indicated that polarized odontoblasts were arranged along the pulp–dentin interface and had high levels of Cx43 expression in the healthy teeth; however, the odontoblast arrangement pattern was slightly changed concomitant to an increase in the Cx43 expression in the carious teeth. Regularly arranged odontoblast-like cells had high levels of the Cx43 expression during the formation of mature dentin, but the odontoblast-like cells were not regularly arranged beneath immature osteodentin in the pulp injury models. Subsequent in vitro experiments demonstrated that Cx43 is upregulated during odontoblastic differentiation of the dental pulp cells, and inhibition or overexpression of Cx43 influence the odontoblastic differentiation. Thus, Cx43 may be involved in the maintenance of odontoblast arrangement patterns, and influence the pulp repair outcomes by the regulation of odontoblastic differentiation.

The effect of three different pulp capping cements on mineralization of dental pulp stem cells

This study evaluated the osteogenic differentiation of human dental pulp stem cells in response to substances released by the pulp capping agents, Biodentine (BD), mineral trioxide aggregate (MTA) and two-paste calcium hydroxide cement (CHC), along with their physicochemical characteristics. The dimensional stability test showed that of the materials studied, only BD met the standards recommended by the International Organization for Standardization (ISO) for pulp capping materials and thus can be used safely. In the chemical tests, BD was the most stable material. In the Alizarin red S test, BD formed the higher amount of mineralized nodules in the mineralizing medium and also formed mineralized nodules in a non-mineralizing medium. BD releases substances that can significantly induce formation of the human dental pulp stem cell-mineralized extracellular matrix, with physicochemical characteristics that are more conducive to pulp repair than those of MTA and CHC.

Evaluation of dentinogenesis inducer biomaterials: an in vivo study

When exposure of the pulp to external environment occurs, reparative dentinogenesis can be induced by direct pulp capping to maintain pulp tissue vitality and function. These clinical situations require the use of materials that induce dentin repair and, subsequently, formation of a mineralized tissue. Objective: This work aims to assess the effect of tricalcium silicate cements and mineral trioxide aggregate cements, including repairing dentin formation and inflammatory reactions over time after pulp exposure in Wistar rats. Methodology: These two biomaterials were compared with positive control groups (open cavity with pulp tissue exposure) and negative control groups (no intervention). The evaluations were performed in three stages; three, seven and twenty-one days, and consisted of an imaging (nuclear medicine) and histological evaluation (H&E staining, immunohistochemistry and Alizarin Red S). Results: The therapeutic effect of these biomaterials was confirmed. Nuclear medicine evaluation demonstrated that the uptake of ^99mTc-Hydroxymethylene diphosphonate (HMDP) showed no significant differences between the different experimental groups and the control, revealing the non-occurrence of differences in the phosphocalcium metabolism. The histological study demonstrated that in mineral trioxide aggregate therapies, the presence of moderate inflammatory infiltration was found after three days, decreasing during follow-ups. The formation of mineralized tissue was only verified at 21 days of follow-up. The tricalcium silicate therapies demonstrated the presence of a slight inflammatory infiltration on the third day, increasing throughout the follow-up. The formation of mineralized tissue was observed in the seventh follow-up day, increasing over time. Conclusions: The mineral trioxide aggregate (WhiteProRoot^®MTA) and tricalcium silicate (Biodentine™) present slight and reversible inflammatory signs in the pulp tissue, with the formation of mineralized tissue. However, the exacerbated induction of mineralized tissue formation with the tricalcium silicate biomaterial may lead to the formation of pulp calcifications

Surface Pre-Reacted Glass Filler Contributes to Tertiary Dentin Formation through a Mechanism Different Than That of Hydraulic Calcium-Silicate Cement

The induction of tissue mineralization and the mechanism by which surface pre-reacted glass-ionomer (S-PRG) cement influences pulpal healing remain unclear. We evaluated S-PRG cement-induced tertiary dentin formation in vivo, and its effect on the pulp cell healing process in vitro. Induced tertiary dentin formation was evaluated with micro-computed tomography (μCT) and scanning electron microscopy (SEM). The distribution of elements from the S-PRG cement in pulpal tissue was confirmed by micro-X-ray fluorescence (μXRF). The effects of S-PRG cement on cytotoxicity, proliferation, formation of mineralized nodules, and gene expression in human dental pulp stem cells (hDPSCs) were assessed in vitro. μCT and SEM revealed that S-PRG induced tertiary dentin formation with similar characteristics to that induced by hydraulic calcium-silicate cement (ProRoot mineral trioxide aggregate (MTA)). μXRF showed Sr and Si ion transfer into pulpal tissue from S-PRG cement. Notably, S-PRG cement and MTA showed similar biocompatibility. A co-culture of hDPSCs and S-PRG discs promoted mineralized nodule formation on surrounding cells. Additionally, S-PRG cement regulated the expression of genes related to osteo/dentinogenic differentiation. MTA and S-PRG regulated gene expression in hDPSCs, but the patterns of regulation differed. S-PRG cement upregulated CXCL-12 and TGF-β1 gene expression. These findings showed that S-PRG and MTA exhibit similar effects on dental pulp through different mechanisms.

Application of a direct pulp capping cement containing S-PRG filler

OBJECTIVES

To evaluate new pulp capping cements containing surface pre-reacted glass ionomer (S-PRG) filler and to investigate ion release kinetics and pH shift of eluates from the cement.

MATERIALS AND METHODS

Molars of Wistar rats were directly pulp capped using three kinds of cement containing S-PRG filler and mineral tri-oxide aggregate (MTA) was used as a control. After 1, 2, or 4 weeks, histological evaluation was performed and differences of tertiary dentin formation were analyzed. Release of Sr²⁺, BO₃^3-, SiO₃^2-, Na⁺, and Al³⁺ ions was determined by inductively coupled plasma-atomic emission spectrometry, and F^- ion release was measured using a fluoride ion selective electrode. The pH of the eluate from each cement after mixing was measured with a pH electrode.

RESULTS

One of S-PRG cements promoted tertiary dentin formation to the same extent as the control (p > 0.05) and it showed a tendency of less inflammatory response. This cement released more BO₃^3- and SiO₃^2-, but less Sr²⁺, Na⁺, and F^- than other S-PRG specimens. Each cement recovered nearly neutral compared with glass ionomer cement.

CONCLUSIONS

S-PRG cement induced tertiary dentin formation based on multiple ion releases, suggesting that it is suitable as a pulp capping material.

CLINICAL RELEVANCE

This new material can be an alternative pulp capping agent to MTA.

Experimental tricalcium silicate cement induces reparative dentinogenesis

OBJECTIVES

To overcome shortcomings of hydraulic calcium-silicate cements (hCSCs), an experimental tricalcium silicate (TCS) cement, named 'TCS 50', was developed. In vitro research showed that TCS 50 played no negative effect on the viability and proliferation of human dental pulp cells, and it induced cell odontogenic differentiation. The objective was to evaluate the pulpal repair potential of TCS 50 applied onto exposed minipig pulps.

METHODS

Twenty permanent teeth from three minipigs were mechanically exposed and capped using TCS 50; half of the teeth were scheduled for 7-day and the other half for 70-day examination (n=10). Commercial hCSCs ProRoot MTA and TheraCal LC were tested as references (n=8). Tooth discoloration was examined visually. After animal sacrifice, the teeth were scanned using micro-computed tomography; inflammatory response at day 7 and day 70, mineralized tissue formation at day 70 were assessed histologically.

RESULTS

Up to 70 days, TCS 50 induced no discoloration, ProRoot MTA generated gray/black discoloration in all teeth. For TCS 50, 40.0% pulps exhibited a mild/moderate inflammation at day 7. No inflammation was detected and complete reparative dentin with tubular structures was formed in all pulps after 70 days. ProRoot MTA induced a similar response, TheraCal LC generated a less favorable response in terms of initial inflammation and reparative dentin formation; however, these differences were not significant (Chi-square test of independence: p>0.05).

SIGNIFICANCE

TCS 50 induced reparative dentinogenesis in minipig pulps. It can be considered as a promising pulp-capping agent, also for aesthetic areas.

A Miniature Swine Model for Stem Cell-Based De Novo Regeneration of Dental Pulp and Dentin-Like Tissue

The goal of this study was to establish mini-swine as a large animal model for stem cell-based pulp regeneration studies. Swine dental pulp stem cells (sDPSCs) were isolated from mini-swine and characterized in vitro. For in vivo studies, we first employed both ectopic and semi-orthotopic study models using severe combined immunodeficiency mice. One is hydroxyapatite-tricalcium phosphate (HA/TCP) model for pulp-dentin complex formation, and the other is tooth fragment model for complete pulp regeneration with new dentin depositing along the canal walls. We found that sDPSCs are similar to their human counterparts exhibiting mesenchymal stem cell characteristics with ability to form colony forming unit-fibroblastic and odontogenic differentiation potential. sDPSCs formed pulp-dentin complex in the HA/TCP model and showed pulp regeneration capacity in the tooth fragment model. We then tested orthotopic pulp regeneration on mini-swine including the use of multi-rooted teeth. Using autologous sDPSCs carried by hydrogel and transplanted into the mini-swine root canal space, we observed regeneration of vascularized pulp-like tissue with a layer of newly deposited dentin-like (rD) tissue or osteodentin along the canal walls. In some cases, dentin bridge-like structure was observed. Immunohistochemical analysis detected the expression of nestin, dentin sialophosphoprotein, dentin matrix protein 1, and bone sialoprotein in odontoblast-like cells lining against the produced rD. We also tested the use of allogeneic sDPSCs for the same procedures. Similar findings were observed in allogeneic transplantation. This study is the first to show an establishment of mini-swine as a suitable large animal model utilizing multi-rooted teeth for further cell-based pulp regeneration studies.

Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview - part II: other clinical applications and complications

Mineral trioxide aggregate (MTA) is a dental material used extensively for vital pulp therapies (VPT), protecting scaffolds during regenerative endodontic procedures, apical barriers in teeth with necrotic pulps and open apices, perforation repairs as well as root canal filling and root-end filling during surgical endodontics. A number of bioactive endodontic cements (BECs) have recently been introduced to the market. Most of these materials have calcium and silicate in their compositions; however, bioactivity is a common property of these cements. These materials include the following: BioAggregate, Biodentine, BioRoot RCS, calcium-enriched mixture cement, Endo-CPM, Endocem, EndoSequence, EndoBinder, EndoSeal MTA, iRoot, MicroMega MTA, MTA Bio, MTA Fillapex, MTA Plus, Neo MTA Plus, Ortho MTA, Quick-Set, Retro MTA, Tech Biosealer, and TheraCal LC. It has been claimed that these materials have properties similar to those of MTA but without the drawbacks. In Part I of this review, the available information on the chemical composition of the materials listed above was reviewed and their applications for VPT was discussed. In this article, the clinical applications of MTA and other BECs will be reviewed for apexification, regenerative endodontics, perforation repair, root canal filling, root-end filling, restorative procedures, periodontal defects and treatment of vertical and horizontal root fractures. In addition, the literature regarding the possible drawbacks of these materials following their clinical applications is reviewed. These drawbacks include their discolouration potential, systemic effects and retreatability following use as a root filling material. Based on selected keywords, all publications were searched regarding the use of MTA as well as BECs for the relevant clinical applications. Numerous publications were found regarding the use of BECs for various endodontic applications. The majority of these investigations compared BECs with MTA. Despite promising results for some materials, the number of publications using BECs for various clinical applications was limited. Furthermore, most studies had several methodological shortcomings and low levels of evidence.