1- Introduction

2- Development of periodontal tissue

3- Periodontal tissue regeneration with somatic NCCs and MSCs

4- Tissue engineering for periodontal tissue regeneration

5- Periodontal tissue regeneration using pluripotent stem cells

6- Discussion

References

Abstract

Periodontitis is commonly observed and is an important concern in dental health. It is characterized by a multifactorial etiology, including imbalance of oral microbiota, mechanical stress, and systemic diseases such as diabetes mellitus. The current standard treatments for periodontitis include elimination of the microbial pathogen and application of biomaterials for treating bone defects. However, the periodontal tissue regeneration via a process consistent with the natural tissue formation process has not yet been achieved. Developmental biology studies state that periodontal tissue is composed of neural crest-derived ectomesenchyme. To elucidate the process of periodontal regeneration, it is essential to understand the developmental background and intercellular cross-talk. Several recent studies have reported the efficacy of transplantation of mesenchymal stem cells for periodontal tissue regeneration. In this review, we discuss the basic knowledge of periodontal tissue regeneration using mesenchymal stem cells and highlight the potential of stem cell-based periodontal regenerative medicine.

Introduction

Periodontal tissues include soft tissues such as gingiva and periodontal ligaments (PDLs) and hard tissues such as the alveolar bones. Periodontitis is usually defined as bone resorption and periodontal tissue destruction due to acute (sometimes aggressive) or chronic inflammation. And periodontitis is very important concerns not only in dental health but also systemic health. The primary treatments for periodontal tissue inflammation include scaling and root planing and periodontal surgery for periodontal tissue reconstruction. Periodontal tissue regeneration using guided tissue regeneration and enamel matrix derivatives are being used for 2e3-wall alveolar bone defects [1,2]. These methods depend on mesenchymal stem cells (MSCs) residing in the periodontal tissues, space provision for the differentiation of MSCs, and the availability of growth factors.

Purpose. This study sought to assess the clinical outcome and survival rate of oral implants placed in individuals with ectodermal dysplasia (ED), based on previously published studies. Methods. An electronic search without time restrictions was undertaken in 5 databases (PubMed/Medline, Web of Science, ScienceDirect, J-Stage, Lilacs). Descriptive statistics, Kaplan Meier estimator and implant failure probability were calculated. Results. 90 publications were included, reporting 228 ED patients that received 1472 implants (1392 conventional, 47 zygomatic, 33 mini-implants). Mean age of the patients was 20.2±6.8 years (2-56). Patients had a mean of 3.2±2.5 maxillary and 2.1±2.6 mandibular permanent teeth (min-max, 0-14). Patients received a mean of 8.2±3.8 implants (1-20). Most implants were placed in the third decade of life, 24.6% of the implants were placed in children (0-17 years of age). 1391 implants had information on follow-up (72 failures, 5.2%). The 20-year CSR was 84.6%. The probability of failure was 4.5% (95%CI 3.5%-5.6%, p<0.001). Additional treatments performed were Le Fort I (99 implants, 20 patients, 3.5% failed), grafting (497 implants, 77 patients, 5.2% failed), distraction osteogenesis (79 implants, 16 patients, 10.1% failed). Mean follow-up was 42.9±41.9 months (min-max, 2-240). Conclusions. Dental implants placed in ED patients, either infants or adults, present a high survival rate (20-year CSR 84.6%).

INTRODUCTION

Ectodermal dysplasia (ED) encompasses a number of genetic syndromes characterized by a congenital defect in two or more of the ectodermal structures of the body. The condition is estimated to occur in approximately 1 in 100,000 live births, and approximately 132 different hereditary syndromes related to ED have been identified (Clarke, 1987). The syndromes usually affect the hair, teeth, nails, sweat glands, craniofacial structures, digits, and occasionally mesodermal abnormalities (Clarke, 1987). The impact on the oral and maxillofacial region includes decreased growth of the mandible and maxilla, deficient development of the maxillary and mandibular alveolar ridges, significant reduction in salivary secretions, and malformations and anomalies of number and shape of primary and permanent teeth (Martin et al., 2005). As many of these patients present oligodontia (absence of 6 or more teeth) or anodontia (complete absence of teeth), a prosthetic rehabilitation is usually desirable. The degree of dentoalveolar tissue deficiency can make an implant-supported prosthesis an appropriate method of definitive occlusal restoration in these patients. However, as the absence of teeth is congenital, this raises the issue of placement of oral implants in growing children, mainly due to the influence of craniofacial growth on the implant’s behavior (Singer et al., 2012). The aim of the present review was to assess the clinical outcome and survival rate of oral implants used for the oral rehabilitation of ED patients.

Visualize an MRI scanner that is less expensive and designed to image a smaller field of view (FOV), like a knee, ankle, or wrist. Such anatomy-specific MRI scanners have been developed and are currently or soon to be available.1 Facilitating this development is an MRI design shift away from using larger and more expensive magnets with excellent field homogeneity and toward accepting smaller, less homogeneous (or less perfect) magnetic fields produced by cheaper and smaller magnets. Image formation can remain feasible by computationally correcting for magnet inhomogeneity and technological advances in pulse sequences and coil design, allowing for MRI scanners to become even cheaper to manufacture.1–3 Now, imagine optimizing these smaller FOV scanners to image teeth, the jaws, and face, and you have the design of an MRI scanner designed for dental use. The physics of producing an image with magnetic resonance are more complex and quite different from computed tomography (CT) or cone beam computed tomography (CBCT) using radiograph. Consequently, MRI has considerably more opportunity for producing useful depictions of human tissues. With the development of dental and face-specific MRI coils, plus the freedom found in sequence design and image processing, researchers can feasibly develop custom techniques to address any number of dental imaging indications: anatomic characterization of hard tissues including bone and teeth for “routine” dental indications like implant placement, caries detection, and fracture detection; anatomic and functional characterization of soft tissues, including periodontal/periapical inflammation, muscle and nerves to characterize neural and pain disorders, and pathologic tissue characterization to diagnose neoplasms and dysplasia without a surgical biopsy; blood flow imaging in both bulk and perfusion forms to assess tissue viability/inflammatory status; and finally, spectroscopy to provide molecular profiles of tissue. Related technological advances in pulse sequence design will likely lead us into uncharted knowledge about normal dental anatomy and physiology as well as pathology and pathophysiology. In this article, the authors provide a brief overview of the use of conventional MRI techniques applied to dental indications, discuss relevant MRI physics in the various steps of image formation, and highlight recent hardware and software technical developments that contribute to (1) the cost/size of MRI decreasing significantly, allowing use in the typical dental clinic, and (2) the facilitation of very specific dental imaging applications that will solve clinical problems.

Traumatic injuries, genetic diseases and external harmful agents such as bacteria and acids often compromise tooth integrity. There is an unmet medical need to develop alternative, innovative dental treatments that complement traditional restorative and surgery techniques. Stem cells have transformed the medical field during the last years. The combination of stem cells with bioactive scaffolds and nanostructured materials turn out to be increasingly beneficial in regenerative dental medicine. Stem cell-based regenerative approaches for the formation of dental tissues will significantly improve treatments and will have a major impact in dental practice. To date there is no established and reliable stem cell-based treatment translated into the dental clinics, however, the advances and improved technological knowledge are promising for successful dental therapies in the near future. Here, we review some of the contemporary challenges in dental medicine and describe the benefits and future possibilities of certain novel approaches in the emerging field of regenerative dentistry.

INTRODUCTION – TOOTH SPECIFICITY

Teeth exert fundamental roles in physiological functions, such as mastication and speech, and are a key feature of facial aesthetics. Tooth functioning relies on its unique combination of hard and soft tissues. Enamel is the hardest tissue of the human body with exceptional physical characteristics to withstand masticatory forces and to protect dental tissues from chemical and bacterial assaults (Figure 1A). 1 Ameloblasts synthesize the organic components of enamel, where hydroxyapatite prisms are formed, but these cells are lost upon tooth eruption, making human teeth incapable of regenerating enamel. Dentin forms a less mineralized matrix tightly interconnected with the enamel and dental pulp, a richly vascularized and innervated soft connective tissue that occupies the central portion of teeth (Figure 1A). Dentin is synthesized by pulp-derived odontoblasts and is characterized by the presence of dentinal tubules that contain the cytoplasmic extensions of odontoblasts as well as sensory nerve endings, thus making dentin highly sensitive to external stimuli and permeable to bacteria upon enamel destruction. Upon tooth injury, a newly formed dentin- or bone-like matrix (i.e., tertiary dentin) protects pulp vitality, but more important damage often leads to pulp necrosis. 1 Teeth are anchored to the alveolar bone by their roots that consist of dentin and cementum. The roots are connected to the bone via the periodontal ligament, a connective tissue that provides stability to the teeth and absorbs mechanical stresses during mastication. 2 Traumatic injuries, infections and genetic diseases, combined with age, often result in tooth loss. It is therefore necessary to develop innovative approaches for the repair/regeneration of damaged or missing dental and alveolar bone tissues.3 However, the unique characteristics of enamel and dentin make tooth regeneration particularly challenging. Technological advancements ranging from digitalization to nanotechnology have become an inherent aspect of many medical fields, and the same applies to dentistry. These progresses aim to offer improved, faster, painless and more effective treatments when compared to methods traditionally used in dental clinics.

Objective: Maillard advanced glycation end products (AGEs) are connected with high dry temperature food processing, color and flavor modification of food products. Oral cavity pathology is strongly influenced by dietary intake. The aim of the present paper is to update current data regarding the sources and metabolism of AGEs, their impact on oral cavity tissues, to discuss and suggest new approaches for the early diagnosis and efficient treatment of AGEs-related oral pathology. Design: This paper is a narrative review of the studies discussing AGEs and mainly the dietary AGEs (dAGEs) sources, metabolism, linkage to general diseases, and specifically the oral cavity pathology. The authors used “PUBMED” and MeSH for the finding of English written and published articles concerning AGEs. There were used the next keywords association: “advanced glycation end products- AGEs” AND “Maillard products”, “AGEs” AND “diet-related disease, “AGEs” AND “salivary biosensor”, “AGEs” AND “metabolic syndrome AGEs”, “AGEs” AND “oral pathology”, “AGEs” AND “dentin AGEs” OR “periodontal AGEs”, “AGEs” AND “diagnosis and monitoring”. The authors used free full-text articles to determine the etiology and physiopathology of AGEs, their association with general diseases and oral cavity disease, assessment methods used in biofluids and tissues, AGEs prevention and treatment approaches. Articles concerning AGEs etiology, metabolism and effect in the human body and specific implication in oral pathology were selected. There were no exclusion criteria in what concerns the study design. Studies in other language than English and articles abstracts were excluded. Criteria of inclusion were free full-text articles written in English. Equally human and animal model studies were included. Regarding the date of publication, all subjects concerning glycation products after 1953 (first published article) were included. Results: Evidence show that AGEs are responsible for inducing low intensity chronic inflammation and thereby, for initiating and/or aggravating chronic diseases. Nowadays, research has demonstrated a significant association between AGEs and dental or periodontal pathology. Moreover, salivary AGEs are consistent with the levels of AGEs in other biological fluids and are correlated with the general and oral pathology. Conclusions: Assessment of salivary AGEs could be a reliable tool for early diagnosis and monitoring diet-related disease.

Introduction

Advanced glycation end products (AGEs) are final products of Maillard reaction. They were discovered by Louis-Camille Maillard in 1912, while he was trying to synthesize in vitro proteins by using a high temperature reaction between amino acids and sugars (Zhang, Ames, Smith, Baynes, & Metz, 2009). In 1953, John E. Hodge published an article in which he divided the reaction and in 1986, the formation of reducing sugar-derived carbonyl products was added to the Maillard chain reaction (Hodge, 1953). It was associated with the flavor and pleasant scent of food, but also with oxidative stress production, local and general inflammation, and last but not least, mutagenic dicarbonyl compounds (Nagao, Takahashi, Yamanaka, & Sugimura, 1979). In medical research, AGEs have been associated to ROS (reactive oxygen species) increase, with consequent generation of oxidative or carbonyl stress. Thus, ROS exert negative effects resulting in inflammatory, autoimmune, diet-related diseases. Comparing to the discovery of the Maillard reaction products, the hypothesis of the implication of AGEs in periodontitis and dental pathology was founded at a later time. Several studies have revealed a strong association between the accumulation of AGEs and the occurrence or worsening of metabolic diseases. However, the routine use of AGEs salivary levels for the diagnosis or monitoring the oral diseases has not been yet reported.

Acknowledgments

References

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Abstract

Many different types of scaffold materials have been used for tissue engineering applications, and hydrogels form one group of materials that have been used in a wide variety of applications.

Hydrogels are hydrophilic polymer networks and they represent an important class of biomaterials in biotechnology and medicine because many hydrogels exhibit excellent biocompatibility with minimal inflammatory responses and tissue damage. Many studies have demonstrated the use of hydrogels in bone-tissue engineering applications. In this report, the summary was conducted on various kinds of polymers and different modification methods of hydrogels to enhance bone formation. The results revealed that hydrogels are applied for bone regeneration and that the modification of hydrogels with bioactive molecules or cell-based approaches resulted in significant increases in new bone formation. This suggests that the use of hydrogels with modification may offer an option for bone-tissue engineering, and further research is needed to identify the biological and physical properties of hydrogels.

Introduction

Many different types of scaffold materials have been used for tissue engineering applications, and hydrogels form one group of materials that have been used in a wide variety of applications (1). A gel is defined as a three-dimensional network swollen by a solvent, and hydrogels are hydrophilic polymer networks that may absorb from 10-20%, up to thousands of times their dry weight in water, and this property allows the cells to adhere, proliferate, and differentiate onto the hydrogels (2).

Hydrogels represent an important class of biomaterials in biotechnology and medicine because many of them exhibit excellent biocompatibility with minimal inflammatory responses and tissue damage, and thus many studies on bone-tissue engineering applications have been undertaken (3-6). In this report, the summary was conducted on various kinds of polymers and different modification methods of hydrogels in bone regeneration applications.