Equivalence of human and bovine dentin matrix molecules for dental pulp regeneration: proteomic analysis and biological function

Differential analysis of the dentin soluble proteomic

OBJECTIVES

To perform a differential analysis of the dentin soluble proteomic and assess the effects of tissue health state and protocol for protein extraction. We hypothesized the dentin soluble proteomic varies according to the tissue physiopathological state (intact vs. caries-affected) and protocol used to extract its proteins.

METHODS

Dentin from freshly extracted non-carious and carious teeth were randomly assigned for protein extraction using either guanidine-HCl/ethylenediaminetetraacetic acid (EDTA) or acetic acid. Protein extracts from intact and caries-affected dentin were processed and digested with trypsin for shotgun label-free proteomic analysis (nLC-ESI-MS/MS). Peptides identification was performed on a nanoACQUITY UPLC-Xevo Q-Tof MS system. Peptides identified with scores of confidence greater than 95% were included in the quantitative statistical analysis embedded in the PLGS software. Differences between experimental conditions were calculated using Student test-t with significance pre-set at α=0.05.

RESULTS

A total of 158 human proteins were identified. Approximately one-sixth of proteins (24/158) were present in at least two different extracts. Conversely, the greatest number of proteins (134/158) was identified uniquely in only one of the extracts. Overall, a larger number of soluble proteins was retrieved from caries-affected than intact dentin (86/158). Likewise, a greater number of proteins was extracted by the guanidine-HCl/EDTA (106/158) in comparison to acetic acid protocol. Several proteins detected in dentin extracts, mainly those from caries-affected teeth, are biological and/or metabolically involved with tissue turnover/remodeling.

CONCLUSION

The identity/abundance of soluble proteins retrieved from and remained in dentin noticeably depend on this tissue physiopathological state and protocol used to remove its minerals.

CLINICAL SIGNIFICANCE

The present findings brought new insight into the proteomic phenotype of human dentin and may provide targets for the development of novel caries disease-prevention therapies.

3D-printed microgels supplemented with dentin matrix molecules as a novel biomaterial for direct pulp capping

OBJECTIVES

To develop a 3D-printed, microparticulate hydrogel supplemented with dentin matrix molecules (DMM) as a novel regenerative strategy for dental pulp capping.

MATERIALS AND METHODS

Gelatin methacryloyl microgels (7% w/v) mixed with varying concentrations of DMM were printed using a digital light projection 3D printer and lyophilized for 2 days. The release profile of the DMM-loaded microgels was measured using a bicinchoninic acid assay. Next, dental pulp exposure defects were created in maxillary first molars of Wistar rats. The exposures were randomly capped with (1) inert material - negative control, (2) microgels, (3) microgels + DMM 500 µg/ml, (4) microgels + DMM 1000 µg/ml, (5) microgels + platelet-derived growth factor (PDGF 10 ng/ml), or (6) MTA (n = 15/group). After 4 weeks, animals were euthanized, and treated molars were harvested and then processed to evaluate hard tissue deposition, pulp tissue organization, and blood vessel density.

RESULTS

All the specimens from groups treated with microgel + 500 µg/ml, microgel + 1000 µg/ml, microgel + PDGF, and MTA showed the formation of organized pulp tissue, tertiary dentin, newly formed tubular and atubular dentin, and new blood vessel formation. Dentin bridge formation was greater and pulp necrosis was less in the microgel + DMM groups compared to MTA.

CONCLUSIONS

The 3D-printed photocurable microgels doped with DMM exhibited favorable cellular and inflammatory pulp responses, and significantly more tertiary dentin deposition.

CLINICAL RELEVANCE

3D-printed microgel with DMM is a promising biomaterial for dentin and dental pulp regeneration in pulp capping procedures.

Treated Dentin Matrix in Tissue Regeneration: Recent Advances

Tissue engineering is a new therapeutic strategy used to repair serious damage caused by trauma, a tumor or other major diseases, either for vital organs or tissues sited in the oral cavity. Scaffold materials are an indispensable part of this. As an extracellular-matrix-based bio-material, treated dentin matrixes have become promising tissue engineering scaffolds due to their unique natural structure, astonishing biological induction activity and benign bio-compatibility. Furthermore, it is important to note that besides its high bio-activity, a treated dentin matrix can also serve as a carrier and release controller for drug molecules and bio-active agents to contribute to tissue regeneration and immunomodulation processes. This paper describes the research advances of treated dentin matrixes in tissue regeneration from the aspects of its vital properties, biologically inductive abilities and application explorations. Furthermore, we present the concerning challenges of signaling mechanisms, source extension, individualized 3D printing and drug delivery system construction during our investigation into the treated dentin matrix. This paper is expected to provide a reference for further research on treated dentin matrixes in tissue regeneration and better promote the development of relevant disease treatment approaches.

In-vitro models of biocompatibility testing for restorative dental materials: From 2D cultures to organs on-a-chip

Dental caries is a biofilm-mediated, diet-modulated, multifactorial and dynamic disease that affects more than 90% of adults in Western countries. The current treatment for decayed tissue is based on using materials to replace the lost enamel or dentin. More than 500 million dental restorations are placed annually worldwide, and materials used for these purposes either directly or indirectly interact with dentin and pulp tissues. The development and understanding of the effects of restorative dental materials are based on different in-vitro and in-vivo tests, which have been evolving with time. In this review, we first discuss the characteristics of the tooth and the dentin-pulp interface that are unique for materials testing. Subsequently, we discuss frequently used in-vitro tests to evaluate the biocompatibility of dental materials commonly used for restorative procedures. Finally, we present our perspective on the future directions for biological research on dental materials using tissue engineering and organs on-a-chip approaches. STATEMENT OF SIGNIFICANCE: Dental caries is still the most prevalent infectious disease globally, requiring more than 500 million restorations to be placed every year. Regrettably, the failure rates of such restorations are still high. Those rates are partially based on the fact that current platforms to test dental materials are somewhat inaccurate in reproducing critical components of the complex oral microenvironment. Thus, there is a collective effort to develop new materials while evolving the platforms to test them. In this context, the present review critically discusses in-vitro models used to evaluate the biocompatibility of restorative dental materials and brings a perspective on future directions for tissue-engineered and organs-on-a-chip platforms for testing new dental materials.

Cells and material-based strategies for regenerative endodontics

<p class = "Abstract" style = "margin: 0 cm; line-height: 32px; font-size: 12 pt; font-family: "Times New Roman", serif; color: rgb(0, 0, 0); "><span lang = "EN-US">The carious process leads to inflammation of pulp tissue. Current care options include root canal treatment or apexification. These procedures, however, result in the loss of tooth vitality, sensitivity, and healing. Pulp capping and dental pulp regeneration are continually evolving techniques to regenerate pulp tissue, avoiding necrosis and loss of vitality. Many studies have successfully employed stem/progenitor cell populations, revascularization approaches, scaffolds or material-based strategies for pulp regeneration. Here we outline advantages and disadvantages of different methods and techniques which are currently being used in the field of regenerative endodontics. We also summarize recent findings on efficacious peptide-based materials which target the dental niche.<o:p></o:p></span></p>

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Pulp infection necessitates removal of necrotic, inflamed and infected tissue.

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Materials used clinically are inert (such as gutta percha, mineral trioxide aggregate).

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Recent developments in materials (angiogenic hydrogels, stem cell composites) have tuneable bioactivity.

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Dental pulp regeneration may now be possible through the use of bioactive systems, that guide regeneration.

Meeting the challenges and clinical requirements for dental regeneration; the New Zealand experience

Disease and trauma leading to tooth loss and destruction of supporting bone is a significant oral handicap, which may be addressed through surgical therapies that aim to regenerate the lost tissue. Whilst complete regeneration of teeth is still aspirational, regeneration of supporting structures (dental pulp, cementum, periodontal ligament, bone) is becoming commonplace, both for teeth and for titanium dental implants that are used to replace teeth. Most grafting materials are essentially passive, however the next generation of oral regenerative devices will combine non-antibiotic antimicrobials and/or osteogenic or inductive factors and/or appropriate multipotential stem cells. The review gives an overview of the approaches taken, including fabrication of novel scaffolds, incorporation of growth factors and cell-based therapies, and discusses the preclinical animal models we employ in the development pathway.

Proteolytic activity and degradation of bovine versus human dentin matrices

Non-human teeth have been commonly used in research as replacements for human teeth, and potential dissimilarities between the dental tissues should be considered when interpreting the outcomes.