Changes in the radicular pulp-dentine complex in healthy intact teeth and in response to deep caries or restorations: A histological and histobacteriological study

Resin tags formation by modified Renewal MI formulations in a carious dentine model

Objectives

To determine which components in a new restorative material (Renewal MI) improve its ability to form resin tags within demineralized dentine.

Methods

Varied components included polylysine (PLS), monocalcium phosphate (MCP), powder to liquid ratio (PLR), 4-methacryloyloxyethyl trimellitate anhydride (4META), and polypropylene glycol dimethacrylate (PPGDMA). Urethane dimethacrylate (UDMA), containing PPGDMA (24 wt%) and 4META (3 wt%), was mixed with glass filler with MCP (8 wt%) and PLS (5 wt%). PLR was 3:1 or 5:1. Reducing MCP and/or PLS to 4 and 2 wt% respectively or fully removing MCP, PLS, 4META or PPGDMA gave 16 formulations in total. Renewal MI, Z250 (with or without Scotchbond Universal adhesive) and Activa were used as commercial comparators. Collagen discs were obtained by totally demineralizing 2 mm thick, human, premolar, coronal dentine discs by immersion in formic acid (4M) for 48 h. The restorative materials were then applied on top (n = 3), before dissolving the collagen in sodium hypochlorite (15%). SEM/EDX was employed to determine resin tags length, composition, and surface coverage.

Results

Tags were >400, 20 and 200 µm and covered 62, 55 and 39% of the adhesion interface for Renewal MI, Scotchbond and Activa, respectively. With experimental formulations, they were 200 and >400 µm long with high vs. low PLR and composed primarily of polymerized monomers. Percentages of the adhesion interface covered varied between 35 and 84%. Reducing PLS or MCP caused a decline in coverage that was linear with their concentrations. Reducing MCP had lesser effect when PLS or PLR were low. Removal of 4META caused a greater reduction in coverage than PPGDMA removal.

Conclusion

PLS, MCP, 4META, PPGDMA and low PLR together enhance Renewal MI tags formation in, and thereby sealing of, demineralized dentine.

Understanding the multi-functionality and tissue-specificity of decellularized dental pulp matrix hydrogels for endodontic regeneration

Dental pulp is the only soft tissue in the tooth which plays a crucial role in maintaining intrinsic multi-functional behaviors of the dentin-pulp complex. Nevertheless, the restoration of fully functional pulps after pulpitis or pulp necrosis, termed endodontic regeneration, remained a major challenge for decades. Therefore, a bioactive and in-situ injectable biomaterial is highly desired for tissue-engineered pulp regeneration. Herein, a decellularized matrix hydrogel derived from porcine dental pulps (pDDPM-G) was prepared and characterized through systematic comparison against the porcine decellularized nerve matrix hydrogel (pDNM-G). The pDDPM-G not only exhibited superior capabilities in facilitating multi-directional differentiation of dental pulp stem cells (DPSCs) during 3D culture, but also promoted regeneration of pulp-like tissues after DPSCs encapsulation and transplantation. Further comparative proteomic and transcriptome analyses revealed the differential compositions and potential mechanisms that endow the pDDPM-G with highly tissue-specific properties. Finally, it was realized that the abundant tenascin C (TNC) in pDDPM served as key factor responsible for the activation of Notch signaling cascades and promoted DPSCs odontoblastic differentiation. Overall, it is believed that pDDPM-G is a sort of multi-functional and tissue-specific hydrogel-based material that holds great promise in endodontic regeneration and clinical translation. STATEMENT OF SIGNIFICANCE: Functional hydrogel-based biomaterials are highly desirable for endodontic regeneration treatments. Decellularized extracellular matrix (dECM) preserves most extracellular matrix components of its native tissue, exhibiting unique advantages in promoting tissue regeneration and functional restoration. In this study, we prepared a porcine dental pulp-derived dECM hydrogel (pDDPM-G), which exhibited superior performance in promoting odontogenesis, angiogenesis, and neurogenesis of the regenerating pulp-like tissue, further showed its tissue-specificity compared to the peripheral nerve-derived dECM hydrogel. In-depth proteomic and transcriptomic analyses revealed that the activation of tenascin C-Notch axis played an important role in facilitating odontogenic regeneration. This biomaterial-based study validated the great potential of the dental pulp-specific pDDPM-G for clinical applications, and provides a springboard for research strategies in ECM-related regenerative medicine.

Anti-inflammatory cerium-containing nano-scaled mesoporous bioactive glass for promoting regenerative capability of dental pulp cells

AIMS

This study aimed to investigate the anti-inflammatory and odontoblastic effects of cerium-containing mesoporous bioactive glass nanoparticles (Ce-MBGNs) on dental pulp cells as novel pulp-capping agents.

METHODOLOGY

Ce-MBGNs were synthesized using a post-impregnation strategy based on the antioxidant properties of Ce ions and proposed the first use of Ce-MBGNs for pulp-capping application. The biocompatibility of Ce-MBGNs was analysed using the CCK-8 assay and apoptosis detection. Additionally, the reactive oxygen species (ROS) scavenging ability of Ce-MBGNs was measured using the 2,7-Dichlorofuorescin Diacetate (DCFH-DA) probe. The anti-inflammatory effect of Ce-MBGNs on THP-1 cells was further investigated using flow cytometry and quantitative real-time polymerase chain reaction (RT-qPCR). Moreover, the effect of Ce-MBGNs on the odontoblastic differentiation of the dental pulp cells (DPCs) was assessed by combined scratch assays, RT-qPCR, western blotting, immunocytochemistry, Alizarin Red S staining and tissue-nonspecific alkaline phosphatase staining. Analytically, the secretions of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Ce-MBGNs were confirmed to effectively scavenge ROS in THP-1-derived macrophages and DPCs. Flow cytometry and RT-qPCR assays revealed that Ce-MBGNs significantly inhibited the M1 polarization of macrophages (Mφ). Furthermore, the protein levels of TNF-α and IL-1β were downregulated in THP-1-derived macrophages after stimulation with Ce-MBGNs. With a step-forward virtue of promoting the odontoblastic differentiation of DPCs, we further confirmed that Ce-MBGNs could regulate the formation of a conductive immune microenvironment with respect to tissue repair in DPCs, which was mediated by macrophages.

CONCLUSIONS

Ce-MBGNs protected cells from self-produced oxidative damage and exhibited excellent immunomodulatory and odontoblastic differentiation effects on DPCs. As a pulp-capping agent, this novel biomaterial can exert anti-inflammatory effects and promote restorative dentine regeneration in clinical treatment. We believe that this study will stimulate further correlative research on the development of advanced pulp-capping agents.

The effect of Par3 on the cellular junctions and biological functions of odontoblast-lineage cells

Perfect intercellular junctions are key for odontoblast barrier function. However, whether Partitioning defective-3 (Par3) is expressed in odontoblasts and its potential effects on odontoblast junctions are unknown. Herein, we investigated the effect of Par3 on cellular junctions and the biological behavior of odontoblast-lineage cells (OLCs). Whole-transcriptome sequencing was used to analyze the effects of Par3 on OLCs and the underlying molecular mechanism. Par3 was detected under physiological and inflammatory conditions in OLCs. To investigate the regulatory effect of Par3 on junctions between mouse OLCs, the effects of Par3 downregulation on the proliferation, migration, cycle and apoptosis of OLCs were detected by 5-ethyl-2'-deoxyuridine (EdU) and Transwell assays and flow cytometry. Western blotting and alizarin red S and alkaline phosphatase (ALP) staining were used to observe the effect of Par3 downregulation on OLC mineralization. Whole-transcriptome sequencing was used to investigate the biological role of Par3 in OLCs and potential molecular mechanisms. Par3 was located along the odontoblast layer in the rat pulp tissue and in the cytoplasm of OLCs. Par3 expression was downregulated under inflammatory conditions. The OLC junctions were discontinuous, and total Zona occluden-1 (ZO-1) expression and expression of ZO-1 at the membrane in OLCs were reduced after Par3 silencing (P < 0.05). Expression of a junction-related protein (ZO-1) was downregulated after the downregulation of Par3 (P < 0.05), and ZO-1 moved from the cell membrane to the cytoplasm. OLC proliferation and migration were enhanced, but apoptosis and mineralization were inhibited in shPar3-transfected cells (P < 0.05). Sequencing identified 2996 differentially expressed genes (DEGs), which were mainly enriched in the response to stimuli and binding. Downregulation of Par3 could overactivate the PI3k-AKT pathway by promoting AKT phosphorylation (P < 0.05). Downregulation of Par3 may disrupt junctions between OLCs by affecting ZO-1 expression and distribution and promote OLC proliferation and migration but inhibit OLC mineralization. Par3 may interact with 14-3-3 proteins for PI3K-AKT pathway activation to affect OLC junctions and function.

Early diagnosis of aortic calcification through dental X-ray examination for dental pulp stones

Vascular calcification, an ectopic calcification exacerbated by aging and renal dysfunction, is closely associated with cardiovascular disease. However, early detection indicators are limited. This study focused on dental pulp stones, ectopic calcifications found in oral tissues that are easily identifiable on dental radiographs. Our investigation explored the frequency and timing of these calcifications in different locations and their relationship to aortic calcification. In cadavers, we examined the association between the frequency of dental pulp stones and aortic calcification, revealing a significant association. Notably, dental pulp stones appeared prior to aortic calcification. Using a rat model of hyperphosphatemia, we confirmed that dental pulp stones formed earlier than calcification in the aortic arch. Interestingly, there were very few instances of aortic calcification without dental pulp stones. Additionally, we conducted cell culture experiments with vascular smooth muscle cells (SMCs) and dental pulp cells (DPCs) to explore the regulatory mechanism underlying high phosphate-mediated calcification. We found that DPCs produced calcification deposits more rapidly and exhibited a stronger augmentation of osteoblast differentiation markers compared with SMCs. In conclusion, the observation of dental pulp stones through X-ray examination during dental checkups could be a valuable method for early diagnosis of aortic calcification risk.

Epigenetic therapeutics in dental pulp treatment: Hopes, challenges and concerns for the development of next-generation biomaterials

This opinion-led review paper highlights the need for novel translational research in vital-pulp-treatment (VPT), but also discusses the challenges in translating evidence to clinics. Traditional dentistry is expensive, invasive and relies on an outmoded mechanical understanding of dental disease, rather than employing a biological perspective that harnesses cell activity and the regenerative-capacity. Recent research has focussed on developing minimally-invasive biologically-based 'fillings' that preserve the dental pulp; research that is shifting the paradigm from expensive high-technology dentistry, with high failure rates, to smart restorations targeted at biological processes. Current VPTs promote repair by recruiting odontoblast-like cells in a material-dependent process. Therefore, exciting opportunities exist for development of next-generation biomaterials targeted at regenerative processes in the dentin-pulp complex. This article analyses recent research using pharmacological-inhibitors to therapeutically-target histone-deacetylase (HDAC) enzymes in dental-pulp-cells (DPCs) that stimulate pro-regenerative effects with limited loss of viability. Consequently, HDAC-inhibitors have the potential to enhance biomaterial-driven tissue responses at low concentration by influencing the cellular processes with minimal side-effects, providing an opportunity to develop a topically-placed, inexpensive bio-inductive pulp-capping material. Despite positive results, clinical translation of these innovations requires enterprise to counteract regulatory obstacles, dental-industry priorities and to develop strong academic/industry partnerships. The aim of this opinion-led review paper is to discuss the potential role of therapeutically-targeting epigenetic modifications as part of a topical VPT strategy in the treatment of the damaged dental pulp, while considering the next steps, material considerations, challenges and future for the clinical development of epigenetic therapeutics or other 'smart' restorations in VPT.

Assessment of the Correlation Between Systemic Conditions and Pulp Canal Calcification: A Case-Control Study

OBJECTIVE

Pulp canal calcification is a dental condition that is characterized by the deposition of mineralized tissue within the dental pulp space. While it is primarily a local phenomenon, recent studies have suggested a potential link between pulp calcification and systemic diseases. This study aimed to determine the correlation between certain systemic diseases, medications, and the presence of pulp canal calcification. Second, it aimed to estimate the prevalence of pulp calcification in the smoker population.

METHODS

A pair-matched case-control observational study was conducted from June 2022 to June 2023 at the Faculty of Dentistry, King Abdulaziz University. Digital periapical and bitewing radiographs were used for case-based sampling. Patients were categorized into two study groups: the cases group (n=100), consisting of patients with pulp canal calcification including either pulp stone, pulp canal obliteration, or both. Whereas the control group (n=100), consisted of patients without pulp canal calcification. Detailed medical histories were obtained to identify the presence of systemic diseases. Additionally, systemic medications and smoking status were documented.

RESULT

The participants were divided into two groups; cases (n=100), diagnosed with teeth calcifications and confirmed by radiographic examination, and controls (n=100), showing no evidence of teeth calcifications. Among the patients in the calcification group, 26% had a history of systemic disease compared to 17% in the control non-calcification group with no significant difference between both groups. No correlation between certain medications and pulp canal calcification. Smoking did not demonstrate a statistically significant association with teeth calcifications (p > 0.05).

CONCLUSION

Pulp calcification on routine radiographic examination could indicate an underlying unnoticed systemic disorder that demands accurate referral and subsequent therapy.

Reparative dentin formation as a possible factor influencing the penetrability of dentin in human teeth with apical periodontitis: an ex vivo study

BACKGROUND

There is still a lack of knowledge regarding the permeability and configuration of infected root dentin. The aim of this ex vivo study was to compare the dentin penetrability of healthy teeth and necrotic teeth with apical periodontitis by evaluating the penetration of sodium hypochlorite (NaOCl) and to analyze the histopathological features of root dentin.

METHODS

Forty-eight molars were collected and divided into two groups. The clinical diagnosis for one group was pulp necrosis with apical periodontitis and the pulp and periapex were normal in the other group. Forty-eight straight roots were divided into two groups: infected and healthy. First, all root canals were stained with 2% methylene blue to visualize penetration after standard root canal instrumentation and irrigation. Transverse sections were obtained, and the dye penetration parameters were measured. The cross sections were processed to 20-30 μm and stained with hematoxylin and eosin for observation of the histopathological changes in the root dentin.

RESULTS

The maximum penetration depth, median penetration depth and penetration percentage of NaOCl solutions, in infected root canals were significantly lower than those in healthy root canals. The histopathological analysis showed that the frequency of reparative dentin formation in infected root canals was significantly greater than that in healthy root canals.

CONCLUSIONS

The dentin penetrability of teeth with necrotic teeth and apical periodontitis was more superficial during root canal irrigation than that of healthy teeth. The histopathological changes in infected radicular dentin, namely the formation of reparative dentin, might be associated with the lower permeability of dentin tubules in human teeth with apical periodontitis.

Effect of full pulpotomy using a calcium silicate-based bioactive ceramic in adult permanent teeth with symptoms indicative of irreversible pulpitis: A retrospective study

BACKGROUND

The authors studied the treatment effect of full pulpotomy using a calcium silicate-based bioactive ceramic in adult permanent teeth with symptoms indicative of irreversible pulpitis.

METHODS

Eighty-one adult permanent teeth with symptoms indicative of irreversible pulpitis in 78 patients aged 18 through 72 years were evaluated for inclusion in the study. After caries excavation, the pulp was amputated to the level of the canal orifices. After hemostasis was achieved, calcium silicate-based bioactive ceramic was placed as the capping agent. The cavity was sealed temporarily with a glass ionomer cement and then restored with flowable resin and composite resin after 2 weeks if no positive symptoms were reported or detected. Postoperative evaluation was performed by means of clinical and radiographic examination at 2 weeks and 3, 6, and 12 months.

RESULTS

Overall success rates of the procedure were 96.3% (78 of 81), 93.8% (76 of 81), 92.6% (75 of 81), and 92.6% (75 of 81) at the 2-week, 3-month, 6-month, and 12-month recall visits, respectively. Six of the 81 teeth failed and required root canal therapy. In these 6 teeth, 3 exhibited severe cold stimuli pain and spontaneous pain at the 2-week follow-up, 2 had no response to electric pulp testing with apical percussion pain and periapical rarefaction at the 3-month follow-up, and 1 tooth exhibited periapical rarefaction and labial mucosal fistula at the 6-month follow-up.

CONCLUSIONS

Under the conditions of this study, full pulpotomy using a calcium silicate-based bioactive ceramic was a successful option for the treatment of adult permanent teeth with carious originated symptoms indicative of irreversible pulpitis.

PRACTICAL IMPLICATIONS

Vital pulp therapy is no longer impossible for adult permanent teeth with carious originated symptoms indicative of irreversible pulpitis.

Regeneration of dentin-pulp complex: Effect of calcium-based materials on hDPSCs differentiation and gene expression

OBJECTIVE

Dentin-pulp complex is object of interest in the regenerative endodontic field as well as the natural function of human dental pulp stem cells (hDPSCs) that may differentiate into specific cells able to repair and/or regenerate both hard and soft dental structures. The aim of the present study was to evaluate the capacity of hDPSCs to differentiate in odontoblastic-like cells by evaluating the expression of specific odontogenic-related genes and to prove the ability of treatment with calcium-based materials such as calcium carbonate (CaCO3), calcium hydroxide (Ca(OH)₂), and mineral trioxide aggregate (MTA).

METHODS

hDPSCs were obtained and isolated from a third molar of a young patient. Odontogenic-related gene expression was assessed unti1 28 days of culture as well as alkaline phosphatase activity (ALP). hDPSCs were cultured in odontoblastic-induction medium used as control, and in presence of different concentrations of CaCO_3, Ca(OH)₂, and MTA.

RESULTS

The results demonstrated an upregulation in odontoblastic cell-related genes, in particular of the early differentiation marker known as matrix extracellular phosphoglycoprotein (MEPE), as well as increased ALP activity and the presence of calcium deposits, mainly by stimulation with calcium derivatives. In this regard, treatment of pulp tissue with CaCO₃, Ca(OH)₂ and even better with MTA seemed to be effective for dentinogenesis.

SIGNIFICANCE

The ease of isolation of hDPSCs from discarded or extracted teeth offers a promising source of autologous cells that may be applied for regenerative purpose in combination with selected bioactive materials. However, further investigations should be conducted to confirm the obtained results.

Development of Rat Caries-Induced Pulpitis Model for Vital Pulp Therapy

Rodent animal models for vital pulp therapy are commonly used in dental research because their tooth anatomy and cellular processes are similar to the anatomy and processes in humans. However, most studies have been conducted using uninfected sound teeth, which makes it difficult to adequately assess the inflammatory shift after vital pulp therapy. In the present study, we aimed to establish a caries-induced pulpitis model based on the conventional rat caries model and then evaluate inflammatory changes during the wound-healing process after pulp capping in a model of reversible pulpitis induced by carious infection. To establish the caries-induced pulpitis model, the pulpal inflammatory status was investigated at different stages of caries progression by immunostaining targeted to specific inflammatory biomarkers. Immunohistochemical staining revealed that both Toll-like receptor 2 and proliferating cell nuclear antigen were expressed in moderate and severe caries-stimulated pulp, indicating that an immune reaction occurred at both stages of caries progression. M2 macrophages were predominant in moderate caries-stimulated pulp, whereas M1 macrophages were predominant in the severe caries-stimulated pulp. Pulp capping in teeth with moderate caries (i.e., teeth with reversible pulpitis) led to complete tertiary dentin formation within 28 d after treatment. Impaired wound healing was observed in teeth with severe caries (i.e., teeth with irreversible pulpitis). During the wound-healing process in reversible pulpitis after pulp capping, M2 macrophages were predominant at all time points; their proliferative capacity was upregulated in the early stage of wound healing compared with healthy pulp. In conclusion, we successfully established a caries-induced pulpitis model for studies of vital pulp therapy. M2 macrophages have an important role in the early stages of the wound-healing process in reversible pulpitis.

Biological Properties of Dental Pulp Stem Cells Isolated from Inflamed and Healthy Pulp and Cultured in an Inflammatory Microenvironment

INTRODUCTION

The aim of this study was to assess whether the biological characteristics of dental pulp stem cells (DPSCs), such as viability, adhesion to dentin, mineralization, and release of immunomodulatory cytokines, are affected by the inflammatory status of the donor tissue and/or the sustained inflammatory environment.

METHODS

DPSCs were isolated from pulps from 3 caries-free teeth (healthy or hDPSCs), and from 3 teeth with irreversible pulpitis or deep caries (unhealthy DPSCs or uDPSCs). The cells were cultured in odontogenic and osteogenic media with or without lipopolysaccharides. Viability was analyzed by MTT assay at days 1, 3, 5, and 7; adhesion to dentin was evaluated through an environmental scanning electron microscope after 48 hours and through MTT assay; mineralization was analyzed with alizarin red staining after 21 days; and the release of proinflammatory (interleukin 6) and immunosuppressive cytokines (interleukin 10) was measured with the enzyme-linked immunosorbent assay after 24 hours and 7 days.

RESULTS

The inflammatory status of the pulp significantly reduced the viability and mineralization capacity of the DPSCs, although it did not affect the adhesion capacity to dentin or the secretion of the proinflammatory interleukin. The inflammatory microenvironment (lipopolysaccharide) only had a significant impact on the secretion of interleukin 6, which was augmented after 7 days.

CONCLUSIONS

The inflammatory status of the dental pulp should be taken into account when the use of DPSCs is intended either for research and/or for application in reparative or regenerative therapies.

Irritation of Dental Sensory Nerves Promotes the Occurrence of Pulp Calcification

INTRODUCTION

Pulp calcification (PC) often appears in strong association with nerve fiber bundles, which indicates the important role of dental nerves in the formation of PC. Additionally, given that sensory nerves and calcitonin gene-related peptide (CGRP) secreted from sensory nerve fibers are involved in physiological and pathological bone formation, we aimed to determine whether chronic irritation of sensory nerves can promote the occurrence of PC.

METHODS

A sensory nerve irritation rat model was established via ligation of the inferior alveolar nerve (IAN), and face grooming behavior was analyzed as a measure of pain sensation. Two months post-surgery, PC was determined by imaging and histologic analyses.

RESULTS

Rats in the IAN-chronic constriction injury (IAN-CCI) group showed spontaneous pain-associated behavior after the operations and pain tolerance on the 60^th postoperative day. The imaging and histological analysis showed more calcified particles in the IAN-innervated first and second molars after day 60 of the dental sensory nerve irritation. These calcified masses had a dentin-like structure that contained sparse, irregularly oriented tubules. Compared to the control and sham groups, the odontoblasts located in the periphery of radicular pulp aligned along a thicker layer of predentin; which expressed more nestin with longer and stouter processes in the IAN-CCI group. Additionally, more CGRP-positive nerves were observed in the IAN-CCI group.

CONCLUSIONS

Irritation of sensory nerves promotes PC formation, and the increased density of CGRP-immunolabeled fibers probably contributes to this process. This highlights the significance of dental sensory nerves in the formation of PC.

Prediction and validation of microbial community function from normal pulp to pulpitis caused by deep dentinal caries

INTRODUCTION

Microbial function changes may be responsible for dental pulp transformation from normal to diseased. However, studies on the prediction and verification of the function of the microbial community in the deep dentine and pulp of caries-induced pulpitis are lacking.

METHODS

This study included 171 cases of deep dentinal caries divided into normal pulp (NP), reversible pulpitis (RP), and irreversible pulpitis (IRP). In Experiment I, the microbial community composition was identified in 111 samples using 16S ribosomal DNA. Function prediction was performed through phylogenetic investigation of communities by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States prediction and qPCR. In Experiment II, different microbiome functions were confirmed in 60 samples using liquid chromatography-tandem mass spectrometry.

RESULTS

In Experiment I, microbial abundance significantly differed in the IRP group compared to the other two groups. The RP and NP groups had the same microbiome composition, but the predicted functional difference between the RP and NP groups pertained to membrane transport (p < .010). The predicted functional difference between the IRP and NP groups pertained to amino-acid, co-factor, and vitamin metabolism (p < .010). In Experiment II, Kyoto Encyclopedia of Genes and Genomes functional annotation revealed that the differential metabolites between the RP and NP groups did not participate in membrane transport; however, the differential metabolites between the IRP and NP groups participated in amino-acid metabolism.

CONCLUSIONS

The near-pulp microbiome in RP and NP with deep dentinal caries had the same differential function. However, amino acid metabolism in near the pulp microbial community differed between IRP and NP with deep dentinal caries.

The scientific management of deep carious lesions in vital teeth using contemporary materials—A narrative review

Aim

The aim of this article is to review the scientific evidence for deep caries removal in permanent vital teeth and the choice of dentine replacement material and restoration of the teeth to maintain long term tooth vitality and function.

Method

The two position statements namely the European Society of Endodontology and the American Association of Endodontists position statements on vital pulp therapy will be scrutinized and compared with regards to the deep caries removal strategy and assessed for evidence of best practice. The properties of materials used to manage vital pulps and the best way to restore the teeth will be reviewed and guidance on the full management of vital teeth will be suggested.

Conclusions

Promoting new treatment modalities for reversible and irreversible pulpitis allowing for pulp preservation should be considered. Although debatable, cases with deep caries should be managed by complete non-selective caries removal which will allow for pulpal management if needed and a more predictable outcome can be expected when using the new materials and treatment modalities of vital pulp therapy.

Effect analysis of a virtual simulation experimental platform in teaching pulpotomy

BACKGROUND

The experimental teaching of pediatric dentistry is a bridge between theoretical study and clinical practice, and virtual simulation technology provides a new method of instruction.

METHODS

We built an experimental teaching platform using virtual simulation technology for vital pulpotomy that includes learning and examination modes. A total of 199 students majoring in stomatology in the fourth year at Sun Yat-Sen University were randomly divided into a control group (conventional teaching mode) and an experimental group (virtual simulation experimental teaching model). The teaching effect was evaluated by theoretical and experimental examination.

RESULTS

We found that both the theoretical and experimental scores of the experimental group were higher than those of the control group, and the theoretical scores of the experimental group after exposure to the virtual simulation experimental teaching platform were also higher than those before the class, with significant differences (P < 0.05). Feedback from the experimental group after the class indicated that the platform reinforced their theoretical knowledge and greatly improved their mastery of operational skills.

CONCLUSIONS

The application of a virtual simulation experimental teaching platform can effectively improve the teaching of pulpotomy.

Evaluation of complete pulpotomy with Biodentine® on mature permanent molars with signs and symptoms of symptomatic irreversible pulpitis: 12 months follow-up

INTRODUCTION

Complete pulpotomy is the removal of the coronal portion of a vital pulp and is a means of preserving the vitality of the remaining root portion. The objective of this study was to evaluate the 12-month success rate of complete pulpotomy with Biodentine® on mature permanent molars with signs and symptoms of symptomatic irreversible pulpitis.

MATERIALS AND METHODS

A total of 68 molars diagnosed with symptomatic irreversible pulpitis in 68 patients aged 20 years and older were included in this study. The exclusion criteria were intraoperative clinical signs of pulp necrosis on the molar to be treated such as no bleeding, or uncontrollable pulp hemorrhage (more than 5 min of hemostasis) on at least one canal. A complete pulpotomy with Biodentine® was performed on molars with symptomatic irreversible pulpitis by the same operator and with the same protocol. At 12-month post-operative follow-up was conducted to evaluate clinical and radiological success.

RESULTS

A total of 66 patients received complete pulpotomy. Fifty-two could be examined at 12 months postoperatively. Clinical and radiological analysis at 12 months postoperatively revealed a success rate of 87% (45/52 molars) and a failure rate of 13% (7/52 molars). There was a relationship between age, tooth type, pre-operative periapical condition and treatment success with P<0.05.

CONCLUSION

Compliance with the indications and protocol for complete pulpotomy with Biodentine® on mature permanent molars with symptomatic irreversible pulpitis gives positive results at 12 month follow-up.

Bacterial Invasion of Pulp Blood Vessels in Teeth with Symptomatic Irreversible Pulpitis

INTRODUCTION

This study described the degenerative changes and infection patterns of the pulp tissue associated with symptomatic irreversible pulpitis.

METHODS

The material consisted of 32 extracted teeth with untreated deep caries that were clinically and histologically diagnosed with irreversible pulpitis and were part of the histopathologic collection of 1 of the authors. The controls consisted of intact teeth with normal uninflamed pulps and teeth with reversible pulpitis. Teeth were processed for histopathologic and histobacteriologic analyses.

RESULTS

All teeth with irreversible pulpitis showed areas of severe acute inflammation, necrosis, microabscesses, and bacterial infection in the pulp chamber. These areas were surrounded by a chronic inflammatory infiltrate, and, at the distance, the pulp tissue was often uninflamed. Bacteria were also observed in the areas surrounding the necrotic foci, both as scattered cells through the extravascular space and at varying numbers within the blood vessel lumen. The number of bacteria and the density of the intravascular bacterial aggregations varied considerably. In one third of the cases, bacteria occurred in the lumen of venules in areas at a considerable distance from the necrotic focus in the coronal third of the root. No intravascular bacteria were noted in the middle and apical segments of the canal. No bacteria were found in the pulps of any of the control specimens.

CONCLUSIONS

Bacterial invasion and colonization of necrotic areas were observed in the pulp of all teeth with caries exposure and symptomatic irreversible pulpitis. Bacterial penetration of blood vessels occurred in all cases, suggesting that this may be an important mechanism of spread of bacterial infection through the pulp tissue in an endodontic infection.

BRIX3000® Papain Gel for Cavity Treatment in the Adult Patient

Tooth decay is a multifactorial disease. Fermentable sugar, host factors, and cariogenic microbial flora are several agents that influence dental structure. In literature, alternative protocols for treating cavities are always of interest in terms of reducing pain and preserving tissue. In this case report, the use of a new gel-based on papain, which has a chemical effect on bacteria and allows the consistency of the altered tissue to be modified, leads to a less traumatic removal of the infected tissue. In this case report, BRIX3000, a gel with papain as its main ingredient, was used to treat an interproximal cavity on an upper premolar of a 35-year-old man frightened of the turbine. After a clinical check of all the systematic conditions and a first view of the oral cavity, the protocol was explained to the patient, and informed consent was obtained. The protocol involved applying the papain gel directly to the cavity, and after 2.5–3 minutes, it was removed. The complete removal of the infected tissue was achieved in three steps. The patient reported no discomfort, and the cavity was completely treated and ready to be restored. In conclusion, BRIX3000 seems to be a good alternative to the turbine in cavity treatment, particularly in patients who have discomfort during traditional treatments and are frightened of the turbine.

Notoginsenoside R1 alleviates TEGDMA-induced mitochondrial apoptosis in preodontoblasts through activation of Akt/Nrf2 pathway-dependent mitophagy

Incomplete polymerization or biodegradation of dental resin materials results in the release of resin monomers such as triethylene glycol dimethacrylate (TEGDMA), causing severe injury of dental pulp cells. To date, there has been no efficient treatment option for this complication, in part due to the lack of understanding of the mechanism underlying these phenomena. Here, for the first time, we found that notoginsenoside R1 (NR1), a bioactive ingredient extracted from Panax notoginseng, exerted an obvious protective effect on TEGDMA-induced mitochondrial apoptosis in the preodontoblast mDPC6T cell line. In terms of the mechanism of action, NR1 enhanced the level of phosphorylated Akt (protein kinase B), resulting in the activation of a transcriptional factor, nuclear factor erythroid 2-related factor 2 (Nrf2), and eventually upregulating cellular ability to resist TEGDMA-related toxicity. Inhibiting the Akt/Nrf2 pathway by pharmaceutical inhibitors significantly decreased NR1-mediated cellular antioxidant properties and aggravated mitochondrial oxidative damage in TEGDMA-treated cells. Interestingly, NR1 also promoted mitophagy, which was identified as the potential downstream of the Akt/Nrf2 pathway. Blocking the Akt/Nrf2 pathway inhibited mitophagy and abolished the protection of NR1 on cells exposed to TEGDMA. In conclusion, these findings reveal that the activation of Akt/Nrf2 pathway-mediated mitophagy by NR1 might be a promising approach for preventing resin monomer-induced dental pulp injury.

Pulp Response to Periodontal Disease: Novel Observations Help Clarify the Processes of Tissue Breakdown and Infection

INTRODUCTION

This study evaluated the pulp response to periodontal disease of increasing severity.

METHODS

The material comprised human teeth affected by moderate (n = 16) to severe (n = 48) periodontal disease and no clinically identified caries lesions. Specimens were obtained by extraction and were processed for histopathologic and histobacteriologic methods.

RESULTS

In 13 of 16 teeth with moderate periodontal disease and vital pulp, no frank accumulations of inflammatory cells were observed. In 22 of 32 teeth with severe periodontal disease and vital pulps, no distinct inflammatory cell accumulations were observed in any portion of the pulp when there was an intact or minimally damaged cementum layer in the corresponding areas. Intravascular bacterial aggregations were detected in pulp blood vessels in 6 teeth with symptomatic pulpitis and severe periodontal disease, which had not reached the root apex in 4 of them. Focal areas of infection and varying accumulations of acute and chronic inflammatory cells were observed throughout the pulp tissue and surrounding these infected blood vessels. When the periodontal pocket reached the apex of single-rooted teeth, the entire canal space was necrotic and colonized by bacteria, often forming biofilms. In multirooted teeth, the pulp response varied according to the root(s) affected. Intrapulpal calcifications were observed in 91% of the teeth. The pulp and cementum of the control teeth showed no pathologic changes or bacteria.

CONCLUSIONS

The pulp showed a significantly detectable response when the cementum coverage was lost or when the periodontal pocket reached the root apex. In the former condition, the pulp response was usually discrete, whereas in the latter, severe reactions usually developed. In some teeth, vessels with a compromised blood flow may serve as avenues for bacteria to invade the pulp via apical or lateral foramina. This indicates that in some teeth the pulp may undergo severe inflammation and necrosis even before the periodontal disease reaches the apical root segment.

Clinical, radiographic, and histological evaluation of three different pulp-capping materials in indirect pulp treatment of primary teeth: a randomized clinical trial

OBJECTIVES

The aim of this randomized, controlled, three-arm parallel group, and double-blinded clinical trial was to evaluate the clinical, radiographic, and histopathological success of three different pulp-capping materials in one-stage indirect pulp treatment of primary teeth.

MATERIALS AND METHODS

The study included a total of 109 patients aged 5-9 years who had primary teeth with deep carious lesions and symptoms of reversible pulpitis. The teeth were divided into three groups according to the pulp-capping agents: (I) hard-setting calcium hydroxide (Dycal) (control group) (n = 36), (II) bioactive tricalcium silicate (Biodentine) (n = 37), and (III) resin-based tricalcium silicate (TheraCal LC) (n = 36). All the teeth were evaluated clinically and radiographically at 6, 12, 18, and 24 months postoperatively. A total of 23 primary mandibular second molars that were in their regular exfoliation period (24-40 months) were extracted and fixed in 10% formaldehyde solution. The specimens were evaluated histologically to assess the integrity of the odontoblastic layer, tertiary dentin formation quality of the dentin formed, severity of pulpitis, and other pulpal changes. Data were analyzed using Fisher's exact test, Pearson's chi-square test, and McNemar's test (p = 0.05).

RESULTS

At the end of the 24-month follow-up period, the clinical and radiographic success rates for Dycal, Biodentine, and TheraCal LC were 100%, 100%, and 93.3%, respectively, and there was no significant difference among the groups (p > 0.05). However, the TheraCal LC group was statistically unsuccessful when compared to the other groups with regard to the integrity of the odontoblastic layer, severity of pulpitis, and other pulpal changes in histological examination (p < 0.05).

CONCLUSION

Indirect pulp capping exhibited high clinical and radiographic success rates in the treatment of primary teeth regardless of the chosen pulp-capping agent. However, histological examination indicated that the pulp status was affected by the chosen capping material especially when selecting a resin-containing material such as TheraCal LC.

CLINICAL RELEVANCE

Resin-free calcium silicate-based materials appear to be more favorable in the indirect pulp treatment of primary teeth, particularly in young-age groups that require long-term success.

Incorporation of amoxicillin-loaded microspheres in mineral trioxide aggregate cement: an in vitro study

Objectives

In this study, we investigated the potential of amoxicillin-loaded polymeric microspheres to be delivered to tooth root infection sites via a bioactive reparative cement.

Materials and Methods

Amoxicillin-loaded microspheres were synthesized by a spray-dray method and incorporated at 2.5% and 5% into a mineral trioxide aggregate cement clinically used to induce a mineralized barrier at the root tip of young permanent teeth with incomplete root development and necrotic pulp. The formulations were modified in liquid:powder ratios and in composition by the microspheres. The optimized formulations were evaluated in vitro for physical and mechanical eligibility. The morphology of microspheres was observed under scanning electron microscopy.

Results

The optimized cement formulation containing microspheres at 5% exhibited a delayed-release response and maintained its fundamental functional properties. When mixed with amoxicillin-loaded microspheres, the setting times of both test materials significantly increased. The diametral tensile strength of cement containing microspheres at 5% was similar to control. However, phytic acid had no effect on this outcome (p > 0.05). When mixed with modified liquid:powder ratio, the setting time was significantly longer than that original liquid:powder ratio (p < 0.05).

Conclusions

Lack of optimal concentrations of antibiotics at anatomical sites of the dental tissues is a hallmark of recurrent endodontic infections. Therefore, targeting the controlled release of broad-spectrum antibiotics may improve the therapeutic outcomes of current treatments. Overall, these results indicate that the carry of amoxicillin by microspheres could provide an alternative strategy for the local delivery of antibiotics for the management of tooth infections.

Regeneration of Pulp-Dentin Complex in a Tooth with Symptomatic Irreversible Pulpitis and Open Apex Using Regenerative Endodontic Procedures

Regenerative endodontic procedures are undertaken on permanent teeth with necrotic pulps and open apices in an attempt to resolve symptoms, to allow the continued development of the root(s), and to reestablish vitality. The available histologic analysis of these teeth has, in the majority of studies, shown that true regeneration of the pulp-dentin complex is not achieved. A recent investigation using an animal model outlined a procedure wherein pulpal amputation a few millimeters short of the apex followed by evoked bleeding allowed the complete regeneration of the normal pulp-dentin complex in immature vital teeth of ferrets. By implementation of this procedure, we report successful pulp regeneration outcome evidenced by continued root development and a positive response to pulp vitality tests in a maxillary central incisor with an open apex diagnosed with symptomatic irreversible pulpitis.

Combined Root Canal Therapies in Multirooted Teeth with Pulpal Disease

The types of pulpal disease found in multirooted teeth may vary from one root canal to the next. Current endodontic treatment strategies allow for options such as regenerative endodontics, vital pulp therapy, or conventional root canal treatment depending on the disease status of the pulp in a specific root canal. A combination of procedures was used in the 3 teeth in this case series based on the assumed pulpal status in each canal. The follow-up ranged from 24-27 months, and in each case the healing response was satisfactory. This report illustrates the use of a combination of treatment procedures that can provide specific treatment benefits in various clinical situations.

Material Pulp Cells and Tissue Interactions

Two increasingly common endodontic procedures, vital pulp therapy (VPT) and regenerative endodontic procedures, rely on dental tissue regeneration/repair mechanisms with the aid of biomaterials. These materials are applied in close contact to the pulpal tissue and are required to be biocompatible, form an antimicrobial seal, not induce staining, and be easy to manipulate. Historically, calcium hydroxide played an important role in VPT. However, over the last 3 decades, significant efforts in research and industry have been made to develop various biomaterials, including hydraulic tricalcium silicate cements. The present review summarized various hydraulic tricalcium silicate cements and their biological properties in clinical procedures, namely VPT and regenerative endodontic procedures.

Evaluation of secondary dentin formation for forensic age assessment by means of semi-automatic segmented ultrahigh field 9.4 T UTE MRI datasets

Dental methods are an important element of forensic age assessment of living persons. After the development of all the teeth, including third molars, is completed, degenerative characteristics can be used to assess age. The radiologically detectable reduction of the dental pulp cavity has been described as such a feature. We investigated the suitability of ultrahigh field 9.4 T ultrashort time echo (UTE) magnetic resonance imaging (MRI) for the evaluation of pulp cavity volume in relation to the total tooth volume in 4 extracted human teeth. The volume calculations were performed after semi-automatic segmentation by software AMIRA using the different intensities of the structures in the MRI dataset. The automatically selected intensity range was adjusted manually to the structures. The visual distinction of pulp and tooth structure was possible in all cases with in-plane resolution < 70 μm. Ratios of tooth/pulp volume were calculated, which could be suitable for age estimation procedures. Intensity shifts within the pulp were not always correctly assigned by the software in the course of segmentation. 9.4 T UTE-MRI technology is a forward-looking, radiation-free procedure that allows the volume of the dental pulp to be determined at high spatial resolution and is thus potentially a valuable instrument for the age assessment of living persons.

Protection against HEMA-Induced Mitochondrial Injury In Vitro by Nrf2 Activation

Dental resin monomers such as 2-hydroxyethyl methacrylate (HEMA) disturb vital cell functions and induce mitochondrial intrinsic apoptosis via generation of oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the gene expression of antioxidative enzymes and plays a crucial role in the maintenance of cellular redox equilibrium and mitochondrial homeostasis. The present study investigated the functional significance of Nrf2 in cellular response toward HEMA. It was found that HEMA stimulation promoted nuclear translocation of Nrf2 and increased Nrf2 and heme oxygenase-1 (HO-1) expression, which was further enhanced by Nrf2 activator tert-butylhydroquinone (tBHQ), but suppressed by Nrf2 inhibitor ML385. Pretreatment of primary human dental pulp cells (hDPCs) with tBHQ protected the cells from HEMA-induced oxidative injury (increased reactive oxygen species production and apoptosis) and mitochondrial impairment (morphological alterations, decreased ATP production, suppressed oxidative phosphorylation activity, depolarization of mitochondrial membrane potential, and disrupted electron transport chain). In contrast, pretreatment with ML385 increased cell sensitivity to these injurious processes. This protective effect on mitochondria could be related to peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α)/nuclear respiratory factor 1 (NRF1) pathway. These results contribute to the understanding of the function of Nrf2 and the development of novel therapies to counteract the adverse effects of dental resin monomers.

Effect of tissue inhibitor of metalloprotease 1 on human pulp cells in vitro and rat pulp tissue in vivo

AIM

To evaluate the dentinogenetic effects of tissue inhibitor of metalloprotease (TIMP1) on human pulp cells in vitro and rat pulp tissue in vivo.

METHODOLOGY

The effect of TIMP1 on pulp cell functions related to hard tissue formation as part of the wound healing process (i.e. biocompatibility, proliferation, differentiation and mineralized nodule formation) was evaluated in vitro and using a direct pulp capping experimental animal model in vivo. The effects of different-sized cavity preparations on hard tissue formation induced by ProRoot MTA at 2 weeks were evaluated using micro-computed tomography (micro-CT). Tertiary dentine formation quality and quantity after pulp capping using TIMP1, ProRoot MTA and phosphate-buffered saline (PBS) was also evaluated after 4 weeks using micro-CT in term of dentine volume (DV), dentine mineral density (DVD) and histological analysis. The data were evaluated by Student's t-test, one-way ANOVA with Tukey's post hoc test, the Kruskal-Wallis test or the Steel-Dwass test. P values < 0.05 were considered statistically significant.

RESULTS

TIMP1 significantly stimulated dental pulp stem cell proliferation, differentiation, and mineralization and was more biocompatible compared with the PBS control (P < 0.05). In the pulp capping model, the amount of tertiary dentine that formed was directly proportional to the size of the pulp exposure; greater amounts of tertiary dentine were observed in pulps with larger exposures after 2 weeks. 4-week samples of TIMP1 and ProRoot MTA had similar characteristics, but both sample significantly induced tertiary dentine formation beneath the cavity compared with PBS (P <  0.05) under standardized cavity preparations.

CONCLUSIONS

TIMP1 has an important role in pulpal wound healing, which makes it a potential biological pulp capping material and candidate molecule for regenerative endodontic therapy.