Effect of demineralising agents on organic and inorganic components of dentine

Alendronate and polyelectrolyte synergically induce biomimetic mineralization of collagen and demineralized dentin

Alendronate (ALN), a potent bisphosphonate, plays a significant role in both bone formation and osteoporosis therapy. However, its potential to promote biomimetic mineralization of type I collagen fibrils and demineralized dentin remains unclear. This study reveals that ALN-pretreated collagen fibrils form ester bonds between the hydroxyl groups of ALN and the carboxyl groups of collagen, accompanied by a reduction in collagen surface potential. Additionally, an adsorption equilibrium of ALN to collagen was achieved at 25 mM ALN. ALN pretreatment facilitates intrafibrillar mineralization of type I collagen fibrils in a dose-dependent manner, as well as mineralization of demineralized dentin in synergy with polyelectrolyte-stabilized Amorphous Calcium Phosphate (ACP) nanoparticles. This process effectively restores the mechanical properties of demineralized dentin to levels comparable to natural dentin. Thus, ALN holds potential for localized applications aimed at promoting remineralization of demineralized dentin.

Impact of Demineralization Time on Enamel Microhardness Reduction and Lesion Depth: An In Vitro Study

INTRODUCTION

The duration of acid exposure is a critical factor in determining an individual's risk of developing caries. The objective of this study was to investigate the correlation between demineralization time and two key parameters: microhardness and depth of an enamel caries lesion.

METHODS

Sixty recently extracted human teeth were mounted in acrylic resin and randomly divided into five groups (n = 12). First, 400 grit and then 1,000 grit sandpaper were applied to the buccal surfaces for five minutes each. Other surfaces, except buccal surfaces, were coated with an acid-resistant varnish. The groups were stored in the same demineralization solution (pH 4.35-4.65), respectively, for a duration of 60, 72, 84, 96, and 108 hours. Before and after exposure to acidic solutions, the surface microhardness of samples (SMH) was evaluated using a Vickers pyramid diamond tip with a 100 gram load applied for 15 seconds. Three measurements were taken from each sample surface, and the average sample value was obtained by averaging the measurements. The depth of the lesions in three specimens from each group was evaluated from five different demineralized pits under a stereomicroscope. Data were analyzed by one-way ANOVA and post-hoc Tukey's honestly significant difference (HSD) tests.

RESULTS

After acid exposure, SMH values significantly decreased in all groups (p = 0.001; p < 0.01) Statistically significant differences were shown between all groups in terms of Δhardness (p < 0.05). After 72 hours of demineralization, the microhardness values tend to decrease more as the exposure time increases (p = 0.001; p < 0.01). The mean lesion depths were varied from 4.01 ± 0.71 µm to 13.7 ± 1.17 µm.

CONCLUSION

Our findings show that there is a positive correlation between the duration of demineralization and lesion depth and a negative correlation between the duration of demineralization and microhardness. We assume that initial lesions may deepen quickly, especially after 72 hours.

Advances in autogenous dentin matrix graft as a promising biomaterial for guided bone regeneration in maxillofacial region: A review

Autogenous dentin matrix (ADM), derived from a patient's extracted tooth, can be repurposed as an autologous grafting material in reconstructive dentistry. Extracted teeth provide a source for ADM, which distinguishes itself with its low rejection rate, osteoinductive capabilities and ease of preparation. Consequently, it presents a viable alternative to autogenous bone. Animal studies have substantiated its effective osteoinductive properties, while its clinical applications encompass post-extraction site preservation, maxillary sinus floor augmentation, and guided bone tissue regeneration. Nevertheless, the long-term efficacy of ADM applied in bone regeneration remains underexplored and there is a lack of standardization in the preparation processes. This paper comprehensively explores the composition, mechanisms underlying osteoinductivity, preparation methods, and clinical applications of ADM with the aim of establishing a fundamental reference for future studies on this subject.

Demineralized dentin matrix for bone regeneration in dentistry: A critical update

Over the last few decades, several new materials and techniques have been developed for bone regeneration. Scaffolds based on demineralized dentin matrix (DDM) present an attractive option due to their availability and several animal and human studies have been conducted to ascertain their utility in regenerative dentistry. The aim of this review was to summarize the recent studies conducted on DDM and used for bone grafts. PubMed, Web of Science, and Scopus were used to search for studies published within the last 10 years. The keywords and terms used were: "demineralized dentine matrix", "bone grafting", "bone augmentation" and "guided tissue regeneration" in various combinations. Original studies (in vitro, animal and human) and systematic reviews were included in the literature search. The literature search initially identified 23 studies (16 animal studies and 7 clinical reports. Most studies included in this review indicate that DDM has demonstrated promising results in a variety of dental and regenerative medicine applications. Further studies are required to completely comprehend its characteristics and prospective applications. Future studies should also focus on optimizing the processing protocols for the production of DDM-based scaffolds.

A glycol chitosan derivative with extrafibrillar demineralization potential for self-etch dentin bonding

OBJECTIVES

Extrafibrillar demineralization is an etching technique that removes only minerals from around the collagen fibrils for resin infiltration. The intrafibrillar minerals are left intact to avoid their replacement by water that is hard for adhesive resin monomers to displace. The present work reported the synthesis of a water-soluble methacryloyloxy glycol chitosan-EDTA conjugate (GCE-MA) and evaluated its potential as an extrafibrillar demineralization agent for self-etch dentin bonding.

METHODS

Glycol chitosan-EDTA was functionalized with a methacryloyloxy functionality. Conjugation was confirmed using Fourier transform-infrared spectroscopy. The GCE-MA was used to prepare experimental self-etch primers. Extrafibrillar demineralization of the primers was evaluated with scaning electron microscopy and transmission electron microscopy. The feasibility of this new self-etch bonding approach was evaluated using microtensile bond strength testing and inhibition of dentin gelatinolytic activity. The antibacterial activity and cytotoxicity of GCE-MA were also analyzed.

RESULTS

Conjugation of EDTA and the methacryloyloxy functionality to glycol chitosan was successful. The functionalized conjugate was capable of extrafibrillar demineralization of mineralized collagen fibrils. Tensile bond strength of the experimental self-etch primer to dentin was comparable to that of phosphoric acid-etched dentin and the commercial self-etch primer Clearfil SE Bond 2. The GCE-MA also inhibited soluble rhMMP-9. In-situ zymography detected minimal fluorescence in hybrid layers conditioned with the experimental primer. The GCE-MA was noncytotoxic and possessed antibacterial activities against planktonic bacteria.

SIGNIFICANCE

Synthesis of GCE-MA brought into fruition a self-etch conditioner that selectively demineralizes the extrafibrillar mineral component of dentin. A self-etch primer prepared with GCE-MA achieved bond strengths comparable to commercial reference adhesive systems.

Demineralized Dentin Matrix for Dental and Alveolar Bone Tissues Regeneration: An Innovative Scope Review

BACKGROUND

Dentin is a permeable tubular composite and complex structure, and in weight, it is composed of 20% organic matrix, 10% water, and 70% hydroxyapatite crystalline matrix. Demineralization of dentin with gradient concentrations of ethylene diamine tetraacetic acid, 0.6 N hydrochloric acid, or 2% nitric acid removes a major part of the crystalline apatite and maintains a majority of collagen type I and non-collagenous proteins, which creates an osteoinductive scaffold containing numerous matrix elements and growth factors. Therefore, demineralized dentin should be considered as an excellent naturally-derived bioactive material to enhance dental and alveolar bone tissues regeneration.

METHOD

The PubMed and Midline databases were searched in October 2021 for the relevant articles on treated dentin matrix (TDM)/demineralized dentin matrix (DDM) and their potential roles in tissue regeneration.

RESULTS

Several studies with different study designs evaluating the effect of TDM/DDM on dental and bone tissues regeneration were found. TDM/DDM was obtained from human or animal sources and processed in different forms (particles, liquid extract, hydrogel, and paste) and different shapes (sheets, slices, disc-shaped, root-shaped, and barrier membranes), with variable sizes measured in micrometers or millimeters, demineralized with different protocols regarding the concentration of demineralizing agents and exposure time, and then sterilized and preserved with different techniques. In the act of biomimetic acellular material, TDM/DDM was used for the regeneration of the dentin-pulp complex through direct pulp capping technique, and it was found to possess the ability to activate the odontogenic differentiation of stem cells resident in the pulp tissues and induce reparative dentin formation. TDM/DDM was also considered for alveolar ridge and maxillary sinus floor augmentations, socket preservation, furcation perforation repair, guided bone, and bioroot regenerations as well as bone and cartilage healing.

CONCLUSION

To our knowledge, there are no standard procedures to adopt a specific form for a specific purpose; therefore, future studies are required to come up with a well-characterized TDM/DDM for each specific application. Likely as decellularized dermal matrix and prospectively, if the TDM/DDM is supplied in proper consistency, forms, and in different sizes with good biological properties, it can be used efficiently instead of some widely-used regenerative biomaterials.