17β-Estradiol Promotes Cementoblast Proliferation and Cementum Formation in Experimental Periodontitis

Consideration of hormonal changes for orthodontic treatment during pregnancy and lactation - a review

Hormonal changes in pregnant and lactating women significantly affect bone metabolism and overall stress levels, positioning them as a unique group within the orthodontic population. Fluctuations in estrogen, progesterone, prolactin, and other hormones are closely linked to bone remodeling and the periodontal tissue's response to inflammation caused by dental plaque. Hormones such as thyrotropin, leptin, and melatonin also play crucial roles in pregnancy and bone remodeling, with potential implications for orthodontic tooth movement. Additionally, adverse personal behaviors and changes in dietary habits worsen periodontal conditions and complicate periodontal maintenance during orthodontic treatment. Notably, applying orthodontic force during pregnancy and lactation may trigger stress responses in the endocrine system, altering hormone levels. However, these changes do not appear to adversely affect the mother or fetus. This review comprehensively examines the interaction between hormone levels and orthodontic tooth movement in pregnant and lactating women, offering insights to guide clinical practice.

Long-term success and influencing factors of regenerative surgery for intra-bony defects: A retrospective cohort study

BACKGROUND

The composite outcome measure (COM) more comprehensively assesses the clinical efficacy of regenerative surgery than a single probing measurement. We aimed to assess long-term success defined by the COM (clinical attachment level [CAL] gain of ≥3 mm and postsurgery probing pocket depth [PPD] ≤ 4 mm) and influencing factors of regenerative surgery using bone substitutes and resorbable collagen membrane (RM) for intra-bony defects (IBDs).

METHODS

We retrospectively collected data from patients who underwent regenerative surgery using deproteinized bovine bone mineral (DBBM) and RM for IBDs. CAL and PPD values were compared at baseline (preoperative), 1 year (short-term), and at the last follow-up (5-10 years). Multivariate logistic regressions were performed to identify factors influencing COM-based long-term success.

RESULTS

Eighty-one defects in 75 teeth of 33 patients who completed follow-up (6.5 ± 1.4 years) were included. One tooth was lost. All defects with complete follow-up exhibited long-term average CAL gain (3.00 ± 2.00 mm, 95% confidence interval [CI]: 2.56-3.44 mm, p < 0.001) and PPD reduction (2.06 ± 1.91 mm, 95% CI: 1.64-2.49 mm, p < 0.001). Long-term success was achieved in 38.8% of IBDs. CAL and PPD values were comparable between 1 year and the last follow-up. Logistic regression analyses revealed that male sex (odds ratio [OR] = 0.23, 95% CI: 0.07-0.75) and bleeding on probing (BOP) during supportive periodontal therapy (OR = 0.96, 95% CI: 0.94-0.99) were risk factors for long-term success.

CONCLUSIONS

Regenerative surgery with DBBM and RM for IBDs can achieve some degree of long-term success defined by COM. However, within this study's limitations, male sex and higher BOP incidence postoperatively are negatively associated with optimal long-term success.

CLINICAL TRIAL NUMBER

ChiCTR2300069016.

Advances in regenerative medicine applications of tetrahedral framework nucleic acid-based nanomaterials: an expert consensus recommendation

With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versatile functions. Especially promising nanostructures are tetrahedral framework nucleic acids (tFNAs), first proposed by Turberfield with the use of a one-step annealing approach. Benefiting from their various merits, such as simple synthesis, high reproducibility, structural stability, cellular internalization, tissue permeability, and editable functionality, tFNAs have been widely applied in the biomedical field as three-dimensional DNA nanomaterials. Surprisingly, tFNAs exhibit positive effects on cellular biological behaviors and tissue regeneration, which may be used to treat inflammatory and degenerative diseases. According to their intended application and carrying capacity, tFNAs could carry functional nucleic acids or therapeutic molecules through extended sequences, sticky-end hybridization, intercalation, and encapsulation based on the Watson and Crick principle. Additionally, dynamic tFNAs also have potential applications in controlled and targeted therapies. This review summarized the latest progress in pure/modified/dynamic tFNAs and demonstrated their regenerative medicine applications. These applications include promoting the regeneration of the bone, cartilage, nerve, skin, vasculature, or muscle and treating diseases such as bone defects, neurological disorders, joint-related inflammatory diseases, periodontitis, and immune diseases.

Mechanisms of sphingosine-1-phosphate (S1P) signaling on excessive stress-induced root resorption during orthodontic molar intrusion

OBJECTIVES

The aim of this study was to investigate cementocyte mechanotransduction during excessive orthodontic intrusive force-induced root resorption and the role of S1P signaling in this process.

MATERIALS AND METHODS

Fifty-four 12-week-old male Wistar rats were randomly divided into 3 groups: control group (Control), intrusive stress application group (Stress), and intrusive stress together with S1PR2-specific antagonist injection group (Stress + JTE). A rat molar intrusion model was established on animals in the Stress and the Stress + JTE groups. The animals in the Stress + JTE group received daily intraperitoneal (i.p.) injection of S1PR2 antagonist JTE-013, while the Control and Stress groups received only the vehicle. Histomorphometric, immunohistochemical, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analyses were performed after euthanizing of the rats.

RESULTS

Root resorption was promoted in the Stress group with increased volumes of resorption pits and amounts of molar intrusion compared with the Control group. The expression levels of cementogenic- and cementoclastic-related factors were affected under excessive intrusive force. Immunohistochemical staining and qRT-PCR analysis showed promoted S1P signaling activities during molar intrusion. Western blot analysis indicated decreased nuclear translocation of β-catenin under excessive intrusive force. Through the administration of JTE-013, S1P signaling activity was suppressed and excessive intrusive force-induced root resorption was reversed. The regulation of S1P signaling could also influence the nuclear translocation of β-catenin and the expressions of cementogenic- and cementoclastic-related factors.

CONCLUSIONS

Root resorption was promoted under excessive orthodontic intrusive force due to the disruption of cementum homeostasis. S1P signaling pathway might play an important role in cementocyte mechanotransduction in this process.

CLINICAL RELEVANCE

The S1P signaling might be a promising therapeutic target for novel therapeutic approaches to prevent external root resorption caused by excessive orthodontic intrusive force.

Weaning, parturitions and illnesses are recorded in rhesus macaque (Macaca mulatta) dental cementum microstructure

Many open questions in evolutionary studies relate to species' physiological adaptations, including the evolution of their life history and reproductive strategies. There are few empirical methods capable of detecting and timing physiologically impactful events such as weaning, parturition and illnesses from hard tissue remains of either extant or extinct species. Cementum is an incremental tissue with post eruption annual periodicity, which covers the tooth root and functions as a recording structure of an animal's physiology. Here we test the hypothesis that it is possible to detect and time physiologically impactful events through the analysis of dental cementum microstructure. Our sample comprises 41 permanent and deciduous teeth from male and female rhesus macaques (Macaca mulatta) with known medical, lifestyle and life history information. We develop a semi-automated method of cementum histological analysis for the purpose of event detection and timing, aimed at significantly reducing the amount of intra- and interobserver errors typically associated with histological analyses. The results of our work show that we were able to detect known events including weaning, parturition, illness and physical trauma with high accuracy (false negative rate = 3.2%; n = 1), and to time them within an average absolute difference of 0.43 years (R²  = .98; p < .05). Nonetheless, we could not distinguish between the several types of stressful events underlying the changes in cementum microstructure. While this study is the first to identify a variety of life history events in macaque dental cementum, laying foundations for future work in conservation and evolutionary studies of both primates and toothed mammals at large, there are some limitations. Other types of analyses (possibly chemical ones) are necessary to tease apart the causes of the stressors.

Principal Component Regression for Forensic Age Determination Using the Raman Spectra of Teeth

Raman spectra of mineralized tooth tissues were used to build a principal component regression (PCR) age determination model for forensic application. A sample of 71 teeth was obtained from donors aging from 11 to 76 years. No particular selection criteria were applied; teeth affected with various pathological processes were deliberately included to simulate a realistic forensic scenario. In order to comply with the nondestructive specimen handling, Raman spectra were collected from tooth surfaces without any previous preparation. Different tooth tissues were evaluated by collecting the spectra from three distinct sites: tooth crown, tooth neck, and root apex. Whole recorded spectra (3500-200 cm^-1) were used for principal component analysis and building of the age determination model using PCR. The predictive capabilities of the obtained age determination models varied according to the spectra collection site. Optimal age determination was attained by using Raman spectra collected from cementum at root apex (R² values of 0.84 and 0.71 for male and female donors, respectively). For optimal performance of that model, male and female donors had to be analyzed separately, as merging both genders into a single model considerably diminished its predictive capability (R²= 0.29).

Vitamin D Receptor Gene Polymorphisms and Cigarette Smoking Impact on Oral Health: A Case-Control Study

Periodontal diseases are multiperspective problems resulting from numerous and diverse exposures that influence the process of initiation or progression of disease. The negative influence of tobacco smoking on oral health is well documented. The aim of the study was to analyze three SNPs in vitamin D receptor gene-rs7975232 (ApaI), rs2228570 (FokI) and rs1544410 (BsmI)-combined with oral health assessment-pH, gingival index, dry mouth, periodontitis, dry socket, redness of oral cavity mucosa, leukoplakia-in a group of cigarette smokers and in non-smokers. Moreover, the possibility of interactions between these polymorphisms and smoking was examined. When comparing the smokers and non-smokers groups, we noticed that rs1544410 heterozygotes were significantly more frequent in the first group, and for the second, both homozygotes were more frequent. Additionally, we observed the impact of interaction between the rs7975232 genotype and smoking status on gingival index. Current smoking was also associated with all analyzed oral health measures except for leucoplakia. Correlation between pH and age in both smokers and non-smokers was also present. Results of our analysis indicate that in our study group lifestyle and aging were leading factors associated with worse oral health status. However, the impact of genetic variants, and also the impact of their interaction with smoking on analyzed parameters was also visible. These results show great possibilities for all levels of prevention of oral diseases by means of education based on evidence-based medicine, but also for incorporating genetic testing and early interventions into this process for predisposed individuals.

Parturitions, menopause and other physiological stressors are recorded in dental cementum microstructure

The life history pattern of recent humans is uniquely derived in many of its aspects including an extended post-reproductive lifespan combined with short interbirth intervals. A number of theories have been proposed to explain the evolution of this unusual pattern. However most have been difficult to test due to the fragmentary nature of the hominin fossil record and the lack of methods capable of inferring such later life history events. In search of a method we tested the hypothesis that the physiologically impactful events of parturition and menopause are recorded in dental cementum microstructure. We performed histomorphological analyses of 47 teeth from 15 individuals with known life history events and were able to detect reproductive events and menopause in all females. Furthermore, we found that other stressful events such as systemic illnesses and incarceration are also detectable. Finally, through the development of a novel analytical method we were able to time all such events with high accuracy (R-squared = 0.92).

Cellular therapy in periodontal regeneration

Periodontitis is a chronic inflammatory condition leading to destruction of the tooth supporting tissues, which if left untreated may cause tooth loss. The treatment of periodontitis mainly aims to arrest the inflammatory process by infection control measures, although in some specific lesions a limited periodontal regeneration can also be attained. Current regenerative approaches are aimed to guide the cells with regenerative capacity to repopulate the lesion and promote new cementum and new connective tissue attachment. The first phase in periodontal tissue regeneration involves the differentiation of mesenchymal cells into cementoblasts to promote new cementum, thus facilitating the attachment of new periodontal ligament fibers to the root and the alveolar bone. Current regenerative approaches limit themselves to the confines of the lesion by promoting the self-regenerative potential of periodontal tissues. With the advent of bioengineered therapies, several studies have investigated the potential use of cell therapies, mainly the use of undifferentiated mesenchymal cells combined with different scaffolds. The understanding of the origin and differentiation patterns of these cells is, therefore, important to elucidate their potential therapeutic use and their comparative efficacy with current technologies. This paper aims to review the in vitro and experimental studies using cell therapies based on application of cementoblasts and mesenchymal stem cells isolated from oral tissues when combined with different scaffolds.

Anti-inflammatory character of Phelligridin D modulates periodontal regeneration in lipopolysaccharide-induced human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Phelligridin D is a hispidin analogue from the mushroom Phellinus baumii that is widely used as a food source in East Asia. This study tested phelligridin D for the anti-inflammatory effect and mechanism in lipopolysaccharide (LPS)-induced human periodontal ligament cells (HPDLCs). The objective of this study was to clarify whether the anti-inflammatory function of phelligridin D affects periodontal regeneration for supporting the HPDLCs of teeth.

MATERIAL AND METHODS

Primary HPDLCs were isolated from healthy teeth and then cultured. The anti-inflammatory function, mechanism and differentiation molecules were verified with reactive oxygen species generation and western blot analysis in LPS-induced HPDLCs.

RESULTS

HPDLCs showed increased inflammatory molecules (intracellular adhesion molecule-1 and vascular cell adhesion molecule-1) and decreased osteogenic proteins (bone morphogenetic protein-7, Osterix and runt-related transcription factor 2) by LPS treatment. Phelligridin D decreased inflammatory molecules and increased osteogenic molecules via downregulation of the extracellular signal-regulated kinase and c-jun N-terminal kinases pathway among the mitogen-activated protein kinase, followed by blocking of nuclear factor kappa-B translocation from cytosol to nucleus. In addition, phelligridin D showed antioxidant properties by reducing reactive oxygen species activity. Finally, the anti-inflammatory and antioxidant function of phelligridin D promoted the periodontal differentiation of HPDLCs.

CONCLUSION

These results suggest that phelligridin D supports teeth on the alveolar bone against outside stress, and may be used as an anti-inflammatory compound for the prevention of periodontitis or periodontal regenerative related disease.

Comparison of the osteogenic, adipogenic, chondrogenic and cementogenic differentiation potential of periodontal ligament cells cultured on different biomaterials

It has been shown that the cellular responses such as adhesion, proliferation and differentiation are influenced by the surface properties, such as the topography or the surface energy. However, less is known about the effect of the chemical composition and type of material on the differentiation potential. The objective of the present paper is to compare the differentiation potential of periodontal ligament cells (HPLC) into adipocytes, osteoblasts, chondroblasts and cementoblasts of three type of materials (metals, ceramics and polymers) without using any biological induction media, but keeping the average roughness values within a limited range of 2.0-3.0μm. The samples were produced as discs of 14×2mm; (n=30 for each type of material). Two samples of each type were chosen; stainless-steel 316L and commercially pure titanium for the metallic samples. The polymers were polymethyl methacrylate and high-density polyethylene, and finally for the ceramics; zirconia and dental porcelain were used. The surfaces properties of the samples (wettability, chemical composition and point of zero charge, PZC) were measured in order to correlate them with the biological response. To evaluate the potential of differentiation, human periodontal ligament cells obtained from extracted teeth were used since they are a promising source for periodontal tissue regeneration. Cell proliferation was initially tested to assure non-toxic effects using a viability colorimetric assay. Finally, the differentiation pattern was evaluated using real time reverse transcription quantitative polymerase chain reaction for 5, 10 and 15days without adding any induction medium. The results indicated that the relative expression of genes related to a particular phenotype were different for each surface. However, not clear correlation between the type of material or their surface properties (morphology, chemical composition, wettability or point of zero charge) and the expression pattern could be identified. For example, bone markers were mainly expressed on cpTi and PMMA; one metallic hydrophobic and one polymeric hydrophilic sample which have similar R_a values but presented different topographical features, although both samples have in common a PZC below 7.

Ethical guidelines, animal profile, various animal models used in periodontal research with alternatives and future perspectives

Laboratory animal models serve as a facilitator to investigate the etiopathogenesis of periodontal disease, are used to know the efficacy of reconstructive and regenerative procedures, and are also helpful in evaluation of newer therapeutic techniques including laser and implant therapies prior to application in the human beings. The aim of this review is to know the different animal models used in various specialties of dental research and to know the ethical guidelines prior to the usage of experimental models with main emphasis on how to refine, replace, and reduce the number of animal models usage in the laboratory. An online search for experimental animal models used in dental research was performed using MEDLINE/PubMed database. Publications from 2009 to May 2013 in the specialty of periodontics were included in writing this review. A total of 652 references were published in PubMed/MEDLINE databases based on the search terms used. Out of 245 studies, 241 were related to the periodontal research published in English from 2009 to 2013. Relevant papers were chosen according to the inclusion and exclusion criteria. After extensive electronic and hand search on animal models, it has been observed that various animal models were used in dental research. Search on animal models used for dental research purpose revealed that various animals such as rats, mice, guinea pigs, rabbit, beagle dogs, goats, and nonhuman primates were extensively used. However, with the new advancement of ex vivo animal models, it has become easy to investigate disease pathogenesis and to test the efficacy of newer therapeutic modalities with the reduced usage of animal models. This review summarized the large amount of literature on animal models used in periodontal research with main emphasis on ethical guidelines and on reducing the animal model usage in future perspective.

Association between vitamin D receptor gene polymorphisms and chronic periodontitis among Libyans

BACKGROUND

Chronic periodontitis (CP) is a common oral disease characterized by inflammation in the supporting tissue of the teeth 'the periodontium', periodontal attachment loss, and alveolar bone loss. The disease has a microbial etiology; however, recent findings suggest that the genetic factors, such as vitamin D receptor (VDR) gene polymorphisms, have also been included.

AIM

Investigation of the relationship between VDR gene polymorphisms and CP among Libyans.

MATERIALS AND METHODS

In this study, we examined 196 unrelated Libyans between the ages of 25 and 65 years, including 99 patients and 97 controls. An oral examination based on Ramfjord Index was performed at different dental clinics in Tripoli and information were collected using a self-reported questionnaire. DNA was extracted from buccal swabs; the VDR ApaI, BsmI, and FokI polymorphisms were genotyped using polymerase chain reaction and were sequenced using Sanger Method.

RESULTS

A significant difference in the newly detected ApaI SNP C/T rs#731236 was found (p=0.022), whereas no significant differences were found in ApaI SNP G/T rs#7975232, BsmI SNP A/G rs#1544410, and FokI SNP A/G rs#2228570 between patients and controls (p=0.939, 0.466, 0.239), respectively.

CONCLUSION

VDR ApaI SNP C/T rs#731236 may be related to the risk of CP in the Libyan population.

Mesenchymal dental stem cells in regenerative dentistry

In the last decade, tissue engineering is a field that has been suffering an enormous expansion in the regenerative medicine and dentistry. The use of cells as mesenchymal dental stem cells of easy access for dentist and oral surgeon, immunosuppressive properties, high proliferation and capacity to differentiate into odontoblasts, cementoblasts, osteoblasts and other cells implicated in the teeth, suppose a good perspective of future in the clinical dentistry. However, is necessary advance in the known of growth factors and signalling molecules implicated in tooth development and regeneration of different structures of teeth. Furthermore, these cells need a fabulous scaffold that facility their integration, differentiation, matrix synthesis and promote multiple specific interactions between cells. In this review, we give a brief description of tooth development and anatomy, definition and classification of stem cells, with special attention of mesenchymal stem cells, commonly used in the cellular therapy for their trasdifferentiation ability, non ethical problems and acceptable results in preliminary clinical trials. In terms of tissue engineering, we provide an overview of different types of mesenchymal stem cells that have been isolated from teeth, including dental pulp stem cells (DPSCs), stem cells from human exfoliated deciduous teeth (SHEDs), periodontal ligament stem cells (PDLSCs), dental follicle progenitor stem cells (DFPCs), and stem cells from apical papilla (SCAPs), growth factors implicated in regeneration teeth and types of scaffolds for dental tissue regeneration.

Key words:Dental stem cells, regenerative dentistry, mesenchymal stem cells, tissue engineering, stem cells.

Periodontal regeneration following implantation of cementum and periodontal ligament-derived cells

BACKGROUND AND OBJECTIVE

The periodontal regeneration of bone defects is often unsatisfactory and could be largely improved by cell therapy. Therefore, the purpose of this study was to evaluate the regenerative potential of implanting canine cementum-derived cells (CDCs) and canine periodontal ligament-derived cells (PDLDCs) in experimentally created periodontal intrabony defects in beagle dogs.

MATERIAL AND METHODS

Cells were obtained from premolars extracted from four beagle dogs. Three-wall intrabony periodontal defects, 3 mm wide and 4 mm deep, were surgically created in their second and fourth premolars and plaque was allowed to accumulate. Once the defects were surgically debrided, periodontal regeneration was attempted by random implantation of collagen sponges embedded with 750,000 CDCs, 750,000 PDLDCs or culture medium. After 3 mo of healing, specimens were obtained and periodontal regenerative outcomes were assessed histologically and histometrically.

RESULTS

The histological analysis showed that a minimal amount of new cementum was formed in the control group (1.56 ± 0.39 mm), whereas in both test groups, significantly higher amounts of new cementum were formed (3.98 ± 0.59 mm in the CDC group and 4.07 ± 0.97 mm in the PDLDC group). The test groups also demonstrated a larger dimension of new connective tissue, resulting in a significantly more coronal level of histological attachment.

CONCLUSION

This proof-of-principle study suggests that cellular therapy, in combination with a collagen sponge, promoted periodontal regeneration in experimental intrabony periodontal defects.

Human cementoblasts express enamel-associated molecules in vitro and in vivo

BACKGROUND AND OBJECTIVE

Cementum is a mineralized tissue that facilitates the attachment of periodontal ligament to the root and surrounding alveolar bone and plays a key role in the regeneration of periodontal tissues. The molecular mechanisms that regulate the proliferation and differentiation of cementoblasts, however, have not been elucidated to date. Enamel molecules are believed to regulate cementoblast differentiation and to initiate the formation of acellular extrinsic fiber cementum. The purpose of this study was therefore to isolate and culture human root-derived cells (HRDC) in order to determine whether they are able to express both cementum and specific enamel proteins and subsequently to confirm these findings in vivo.

MATERIAL AND METHODS

Human root-derived cells were isolated and expanded in vitro. Cells were characterized using RT-PCR, immunostaining, western blotting and by examination of total mRNA to determine the expression of cementum and enamel markers. Human periodontal tissues were also examined for the expression of enamel-related proteins by immunostaining.

RESULTS

We showed that HRDC express mRNA corresponding to ameloblastin (AMBN), amelogenin (AMEL), enamelin (ENAM), tuftelin (TUFT) and cementum-associated molecules such as cementum protein 1 (CEMP1) and cementum attachment protein (CAP). Western blotting revealed that HRDC express both AMEL and AMBN gene products, as well as the cementum markers CEMP1 and CAP. In vivo, we have showed that AMBN and AMEL are expressed by cementoblasts lining cementum, paravascular cells and periodontal ligament cells.

CONCLUSION

These results suggest that enamel-associated and cementum-associated proteins could act synergistically in regulating cementoblast differentiation and cementum deposition and offer new approaches on how the cementogenesis process is regulated.