Simvastatin versus Calcium Hydroxide Direct Pulp Capping of Human Primary Molars: A Randomized Clinical Trial

Tissue engineering approaches for dental pulp regeneration: The development of novel bioactive materials using pharmacological epigenetic inhibitors

The drive for minimally invasive endodontic treatment strategies has shifted focus from technically complex and destructive root canal treatments towards more conservative vital pulp treatment. However, novel approaches to maintaining dental pulp vitality after disease or trauma will require the development of innovative, biologically-driven regenerative medicine strategies. For example, cell-homing and cell-based therapies have recently been developed in vitro and trialled in preclinical models to study dental pulp regeneration. These approaches utilise natural and synthetic scaffolds that can deliver a range of bioactive pharmacological epigenetic modulators (HDACis, DNMTis, and ncRNAs), which are cost-effective and easily applied to stimulate pulp tissue regrowth. Unfortunately, many biological factors hinder the clinical development of regenerative therapies, including a lack of blood supply and poor infection control in the necrotic root canal system. Additional challenges include a need for clinically relevant models and manufacturing challenges such as scalability, cost concerns, and regulatory issues. This review will describe the current state of bioactive-biomaterial/scaffold-based engineering strategies to stimulate dentine-pulp regeneration, explicitly focusing on epigenetic modulators and therapeutic pharmacological inhibition. It will highlight the components of dental pulp regenerative approaches, describe their current limitations, and offer suggestions for the effective translation of novel epigenetic-laden bioactive materials for innovative therapeutics.

Direct pulp capping in asymptomatic carious primary molars using three different pulp capping materials: a prospective clinical trial

PURPOSE

Τo assess the outcome of direct pulp capping in asymptomatic carious primary molars using three pulp capping materials.

METHODS

In this prospective clinical trial, carious primary molars free of irreversible pulp inflammation signs and symptoms, with negative pain history and pulp exposure following caries removal were included. Teeth were divided into groups: A: Ca(OH)₂, B: Pure Portland cement^®, C: Biodentine™. Following anaesthesia, isolation, caries removal, pulp exposure, hemorrhage control, pulp capping, additional lining in groups A, B, teeth were restored with composite resin. Descriptive statistics, Chi-squared and Fisher's exact tests, Kaplan-Meier survival curves, multivariable random effects Cox regression model were performed.

RESULTS

Sixty-six patients (25 girls, 41 boys) with mean age 7.2 (± 1.7) years participated. The mean follow-up time was 13 months. Seventy-nine primary molars were assigned to groups A (n = 27), B (29), C (n = 23). The overall failure was 16% and the distribution by group was: A: 5 teeth, B: 5 teeth, C: 3 teeth. No significant differences in failure rates between capping materials, tooth types, age bands and genders were identified.

CONCLUSIONS

Direct pulp capping in asymptomatic carious primary molars may be an acceptable option, when treating an exposed pulp with bioceramic materials as pulp capping agents.

In Vitro and In Vivo Efficacy of New Composite for Direct Pulp Capping

Objectives

To investigate physicochemical properties, dentin bonding, cytotoxicity, and in vivo pulp response of experimental self-adhesive composites tailored to direct pulp capping.

Materials and Methods

Experimental composites were prepared with beta-tricalcium phosphate and hydroxyapatite nanoparticles adsorbed with simvastatin and glutathione added at 0% (control resin), 1 wt% (Res 1%), and 10 wt% (Res 10%). A commercial light-curable calcium hydroxide (Ca(OH)₂) (Ultra-Blend Plus) was used as control material. The physicochemical properties investigated were flexural strength and modulus, calcium release, and degree of conversion. Dentin bonding was assessed by the push-out test. Proliferation and cell counting assays were performed to evaluate in vitro cytotoxicity using fluorescence microscopy. In vivo pulp capping was performed on molars of Wistar rats, which were euthanized after 14 days and evaluated by histological analysis.

Results

No statistical difference was observed in flexural strength and cell viability (p > 0.05). Res 10% presented higher modulus than control resin and Ca(OH)₂. Also, Res 10% attained statistically higher degree of conversion when compared to other experimental composites. Ca(OH)₂ showed higher calcium release after 28 and 45 days of storage, with no statistical difference at 45 days to Res 10%. All experimental composites achieved significantly higher bond strength when compared to Ca(OH)₂. While no significant difference was observed in the cell proliferation rates, resins at lower concentrations showed higher cell viability. In vivo evaluation of pulp response demonstrated no pulp damage with experimental composites.

Conclusions

The experimental composite investigated in this study achieved adequate physicochemical properties with minor in vivo pulpal inflammation and proved to be a valuable alternative for direct pulp capping.

Simvastatin Induces In Vitro Mineralization Effects of Primary Human Odontoblast-Like Cells

Simvastatin (SV) is an often prescribed statin reducing the LDL-concentration in circulating blood. The aim of this study was to evaluate the pleiotropic effects of SV to primary human odontoblast-like cells. Twenty four wisdom teeth of different subjects were extracted and the pulp tissue was removed and minced under sterile conditions. After mincing, the requested cells were passaged according to established protocols. Osteoblastic marker (ALP conversion), viability and mineralization were determined at days 14, 17 and 21 after simvastatin exposition (0.01 µM, 0.1 µM, 1.0 µM, 2.0 µM). The sample size per group was 24 cultures with three replicates per culture for ALP-conversion and mineralization and 6 replicates for viability. A Kruskal–Wallis test was used for statistical analysis. After adding SV, viability was significantly (p < 0.01) decreased in a time- and dose-dependent manner, whereas after 21 days, mineralization was significant (p < 0.01). ALP-conversion in groups with SV concentrations of 1 and 2 µM SV was significantly (p < 0.01) increased. Pleiotropic effects regarding mineralization in higher SV concentrations were possibly induced via alternative mineralization pathways as almost equal elevations of ALP conversion were not evident in the control and experimental groups.

The effects of statins on dental and oral health: a review of preclinical and clinical studies

The statin family of drugs are safe and effective therapeutic agents for the treatment of arteriosclerotic cardiovascular disease (CVD). Due to a wide range of health benefits in addition to their cholesterol lowering properties, statins have recently attracted significant attention as a new treatment strategy for several conditions, which are not directly related to normalizing a lipid profile and preventing CVD. Statins exert a variety of beneficial effects on different aspects of oral health, which includes their positive effects on bone metabolism, their anti-inflammatory and antioxidant properties, and their potential effects on epithelization and wound healing. Additionally, they possess antimicrobial, antiviral, and fungicidal properties, which makes this class of drugs attractive to the field of periodontal diseases and oral and dental health. However, to the best of our knowledge, there has been no comprehensive study to date, which has investigated the effects of statin drugs on different aspects of dental and oral health. Therefore, the primary objective of this paper was to review the effect of statins on dental and oral health. Results of our extensive review have indicated that statins possess remarkable and promising effects on several aspects of dental and oral health including chronic periodontitis, alveolar bone loss due to either extraction or chronic periodontitis, osseointegration of implants, dental pulp cells, orthodontic tooth movement, and orthodontic relapse, tissue healing (wound/bone healing), salivary gland function, and finally, anti-cancer effects. Hence, statins can be considered as novel, safe, inexpensive, and widely-accessible therapeutic agents to improve different aspects of dental and oral health.

[An experimental study of simvastatin-collagen composite sponge as a direct pulp capping material in rat molars]

OBJECTIVE

To assess the feasibility and efficacy of simvastatin-collagen composite sponge as a novel, direct pulp capping material.

METHODS

A total of 120 Sprague-Dawley rats were randomly divided into three groups: the simvastatin-collagen composite sponge group (SIM group), the collagen sponge group (CS group), and the Ca(OH)2 group (CH group). An endodontic entry cavity was prepared on the occlusion of the first molar on the left maxillary of each rat. The contralateral teeth were utilized as the normal control group. The rats were experimented after 1, 3, 7, 14, and 28 days. X-ray observations were conducted and the specimens underwent hematoxylin-eosin (HE) and Masson's Thichrome staining. Dentin bridge formations and pulpal biology reactions were evaluated histopathologically.

RESULTS

X-ray results: high-density images could be observed on the pulp exposure sites in the CH group on the 28th day. In the SIM group, high-density images could be observed after 14 and 28 days, whereas in the CS group, high-density images were not observable in the exposed area. HE and Masson's Thichrome staining results: different degrees of inflammation under the cavity were detected in the three groups at different time points. The inflammatory reaction of the CS group was the most serious. The degree of the inflammatory reaction varied significantly between the SIM and the CS groups on the 14th and 28th days (P<0.01). The inflammatory reaction in the SIM group was lighter than in the CH group. There was a statistical difference between the SIM and the CH groups on the 14th day (P<0.05). During the observation period, the SIM group induced the best and fastest formation of reparative dentin. As for dentin bridge formation, a significantly higher complete bridge rate was observed in the SIM group than in the CH and in the CS groups on the 14th day (P<0.05) and for the SIM and the CH groups compared with the CS group on the 28th day (P<0.05).

CONCLUSIONS

The simvastatin-collagen composite sponge exhibited satisfactory biocompatibility with the pulp tissue and promoted the formation of reparative dentin. The application of simvastatin-collagen composite sponge as a pulp-capping material has satisfactory potential.

Direct pulp capping versus pulpotomy with MTA for carious primary molars: a randomised clinical trial

AIM

Aim of this randomised clinical trial was to compare the outcome of direct pulp capping (DPC) versus pulpotomy, both with MTA, for carious primary molars.

METHODS

Healthy, cooperative children aged 3-9 years with at least one deep carious primary molar requiring vital pulp therapy were included. Data on the primary outcome (all-cause failure) and secondary outcomes (clinical or radiographic failure) were collected blindly semi-annually for a minimum of 1 year up to 3 years and analysed with survival analysis and generalised linear regression at alpha = 5%.

RESULTS

A total of 74 children were randomly allocated on 1:1 basis to DPC (35 children; 40 teeth) or pulpotomy (39 children; 57 teeth). Survival from all-cause failure was 79.7% [95% confidence interval (CI) 69.3-86.9%] at 12 months and 66.0% (95% CI 53.4-76.0%) at 24 months which remained stable up to 36 months, with no differences between groups (P > 0.05). No significant difference was found in the survival rate of the two groups for all-cause [hazard ratio (HR) = 0.95; 95% CI 0.45-2.01; P = 0.88], clinical (HR = 0.74; 95% CI 0.0.19-2.92; P = 0.66), or radiographic failure (HR = 0.80; 95% CI 0.0.36-1.82; P = 0.60) throughout the 3-year follow-up. Regression analysis indicated that needing a second attempt for haemorrhage control was associated with higher clinical failure rate. All-case failure was significantly different for class II versus occlusal cavities and in the latter cavities pulpotomy performed better (P < 0.001).

CONCLUSION

The results of the current trial indicate that both DPC and pulpotomy can be reliable options for the treatment of deep carious primary molars in cooperative children, in carefully selected cases.

Efficacy of articaine infiltration versus lidocaine inferior alveolar nerve block for pulpotomy in mandibular primary second molars: A randomized clinical trial

Background: Successful anesthesia is a major concern in during pulpotomy treatment. The aim of this study was to compare the anesthetic efficacy of inferior alveolar nerve block using 2% lidocaine and buccal infiltration using 4% articaine for pulpotomy of mandibular primary second molars.

Methods: This randomized cross-over clinical trial was performed in 23 children (five to eight-year-old) from July through November 2016, referred to the Department of Pediatric Dentistry, Tehran University of Medical Sciences who needed pulpotomy treatment in both mandibular primary second molars. The Patients’ feeling during injection and their behavior during pulpotomy and post-treatment complications were registered. Wilcoxon Signed Ranks test was used for analyzing the data. A significant level of differences was taken as p≤ 0.05.

Results: Patients’ feeling during injection and post-treatment complications did not significantly differ between two groups (p>0.05). Patients’ behavior during pulpotomy was significantly better in articaine group (p=0.004).

Conclusion: Articaine buccal infiltration can be used successfully in pulpotomy of mandibular primary second molars. Iranian Registry of Clinical Trial: (IRCT2015042321484N2).

Simvastatin and nanofibrous poly(l-lactic acid) scaffolds to promote the odontogenic potential of dental pulp cells in an inflammatory environment

In this study, we investigated the anti-inflammatory, odontogenic and pro-angiogenic effects of integrating simvastatin and nanofibrous poly(l-lactic acid) (NF-PLLA) scaffolds on dental pulp cells (DPCs). Highly porous NF-PLLA scaffolds that mimic the nanofibrous architecture of extracellular matrix were first fabricated, then seeded with human DPCs and cultured with 0.1 μM simvastatin and/or 10 μg/mL pro-inflammatory stimulator lipopolysaccharide (LPS). The gene expression of pro-inflammatory mediators (TNF-α, IL-1β and MMP-9 mRNA) and odontoblastic markers (ALP activity, calcium content, DSPP, DMP-1 and BMP-2 mRNA) were quantified after long-term culture in vitro. In addition, we evaluated the scaffold's pro-angiogenic potential after 24 h of in vitro co-culture with endothelial cells. Finally, we assessed the combined effects of simvastatin and NF-PLLA scaffolds in vivo using a subcutaneous implantation mouse model. The in vitro studies demonstrated that, compared with the DPC/NF-PLLA scaffold constructs cultured only with pro-inflammatory stimulator LPS, adding simvastatin significantly repress the expression of pro-inflammatory mediators. Treating LPS+ DPC/NF-PLLA constructs with simvastatin also reverted the negative effects of LPS on expression of odontoblastic markers in vitro and in vivo. Western blot analysis demonstrated that these effects were related to a reduction in NFkBp65 phosphorylation and up-regulation of PPARγ expression, as well as to increased phosphorylation of pERK1/2 and pSmad1, mediated by simvastatin on LPS-stimulated DPCs. The DPC/NF-PLLA constructs treated with LPS/simvastatin also led to an increase in vessel-like structures, correlated with increased VEGF expression in both DPSCs and endothelial cells. Therefore, the combination of low dosage simvastatin and NF-PLLA scaffolds appears to be a promising strategy for dentin regeneration with inflamed dental pulp tissue, by minimizing the inflammatory reaction and increasing the regenerative potential of resident stem cells.

STATEMENT OF SIGNIFICANCE

The regeneration potential of stem cells is dependent on their microenvironment. In this study, we investigated the effect of the microenvironment of dental pulp stem cells (DPSCs), including 3D structure of a macroporous and nanofibrous scaffold, the inflammatory stimulus lipopolysaccharide (LPS) and a biological molecule simvastatin, on their regenerative potential of mineralized dentin tissue. The results demonstrated that LPS upregulated inflammatory mediators and suppressed the odontogenic potential of DPSCs. Known as a lipid-lowing agent, simvastatin was excitingly found to repress the expression of pro-inflammatory mediators, up-regulate odontoblastic markers, and exert a pro-angiogenic effect on endothelial cells, resulting in enhanced vascularization and mineralized dentin tissue regeneration in a biomimetic 3D tissue engineering scaffold. This novel finding is significant for the fields of stem cells, inflammation and dental tissue regeneration.

Physical evaluation of a new pulp capping material developed from portland cement

Background

This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material.

Material and Methods

The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide.

Results

The statistical analysis was performed with ANOVA and Duncan’s post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001).

Conclusions

Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material.

Key words:Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength.

A review on vital pulp therapy in primary teeth

Maintaining deciduous teeth in function until their natural exfoliation is absolutely necessary. Vital pulp therapy (VPT) is a way of saving deciduous teeth. The most important factors in success of VPT are the early diagnosis of pulp and periradicular status, preservation of the pulp vitality and proper vascularization of the pulp. Development of new biomaterials with suitable biocompatibility and seal has changed the attitudes towards preserving the reversible pulp in cariously exposed teeth. Before exposure and irreversible involvement of the pulp, indirect pulp capping (IPC) is the treatment of choice, but after the spread of inflammation within the pulp chamber and establishment of irreversible pulpitis, removal of inflamed pulp tissue is recommended. In this review, new concepts in preservation of the healthy pulp tissue in deciduous teeth and induction of the reparative dentin formation with new biomaterials instead of devitalization and the consequent destruction of vital tissues are discussed.

Nano-hydroxyapatite and calcium-enriched mixture for pulp capping of sound primary teeth: a randomized clinical trial

INTRODUCTION

Nano-hydroxyapatite (NHA) has been used for regeneration of osseous defects. Calcium-enriched mixture (CEM) cement is also used for various dental treatments. This trial compared the efficacy of NHA and CEM cement for direct pulp capping (DPC) of sound primary teeth.

METHODS AND MATERIALS

In this randomized clinical trial with split-mouth design, after attaining informed consent, 20 sound primary canines scheduled for orthodontic extraction, were selected. After mechanical pulp exposure, the exposed site was capped with either NHA or CEM cement and then immediately restored with glass-ionomer and resin composite. The teeth were extracted after two months and examined histologically. Parameters of hard tissue bridge (HTB) formation, its type and quality as well as pulpal inflammation scores were compared between the two experimental groups. The data were analyzed using the Mann Whitney U and Fisher's exact test. The level of significance was set at 0.001.

RESULTS

All CEM specimens showed inflammation score of 0 (less than 10%). However, in NHA group, inflammation scores of 0 (less than 10%), 1 (10%-30%) and 2 (30%-50%) were observed in 2 (20%), 4 (40%) and 4 (40%) specimens, respectively (P<0.001). HTB was formed in all CEM specimens while it was developed in 2 specimens of NHA (20%; P<0.001). All CEM specimens showed normal pulp; only two cases in NHA group (20%) demonstrated uninflamed normal pulp.

CONCLUSION

CEM cement was superior to NHA as a DPC agent in terms of HTB formation and pulp inflammation scores. It is a suitable material for the DPC of primary teeth.

A review on vital pulp therapy in primary teeth

Maintaining deciduous teeth in function until their natural exfoliation is absolutely necessary. Vital pulp therapy (VPT) is a way of saving deciduous teeth. The most important factors in success of VPT are the early diagnosis of pulp and periradicular status, preservation of the pulp vitality and proper vascularization of the pulp. Development of new biomaterials with suitable biocompatibility and seal has changed the attitudes towards preserving the reversible pulp in cariously exposed teeth. Before exposure and irreversible involvement of the pulp, indirect pulp capping (IPC) is the treatment of choice, but after the spread of inflammation within the pulp chamber and establishment of irreversible pulpitis, removal of inflamed pulp tissue is recommended. In this review, new concepts in preservation of the healthy pulp tissue in deciduous teeth and induction of the reparative dentin formation with new biomaterials instead of devitalization and the consequent destruction of vital tissues are discussed.