Amelogenin: A novel protein with diverse applications in genetic and molecular profiling

Biomimetic Remineralization of Artificial Caries Lesions with a Calcium Coacervate, Its Components and Self-Assembling Peptide P11-4 In Vitro

The application of calcium coacervates (CCs) may hold promise for dental hard tissue remineralization. The aim of this study was to evaluate the effect of the infiltration of artificial enamel lesions with a CC and its single components including polyacrylic acid (PAA) compared to that of the self-assembling peptide P11-4 in a pH-cycling (pHC) model. Enamel specimens were prepared from bovine incisors, partly varnished, and stored in demineralizing solution (DS; pH 4.95; 17 d) to create two enamel lesions per sample. The specimens were randomly allocated to six groups (n = 15). While one lesion per specimen served as the no-treatment control (NTC), another lesion (treatment, T) was etched (H3PO4, 5 s), air-dried and subsequently infiltrated for 10 min with either a CC (10 mg/mL PAA, 50 mM CaCl2 (Ca) and 1 M K2HPO4 (PO4)) (groups CC and CC + DS) or its components PAA, Ca or PO4. As a commercial control, the self-assembling peptide P11-4 (CurodontTM Repair, Credentis, Switzerland) was tested. The specimens were cut perpendicularly to the lesions, with half serving as the baseline (BL) while the other half was exposed to either a demineralization solution for 20 d (pH 4.95; group CC + DS) or pHC for 28 d (pH 4.95, 3 h; pH 7, 21 h; all five of the other groups). The difference in integrated mineral loss between the lesions at BL and after the DS or pHC, respectively, was analyzed using transversal microradiography (ΔΔZ = ΔZpHC - ΔZbaseline). Compared to the NTC, the mineral gain in the T group was significantly higher in the CC + DS, CC and PAA (p < 0.05, Wilcoxon). In all of the other groups, no significant differences between treated and untreated lesions were detected (p > 0.05). Infiltration with the CC and PAA resulted in a consistent mineral gain throughout the lesion body. The CC as well as its component PAA alone promoted the remineralization of artificial caries lesions in the tested pHC model. Infiltration with PAA further resulted in mineral gain in deeper areas of the lesion body.

Analysis of a Yp11.2 region deletion in a Chinese female with Turner syndrome: A case report

In recent years, an increasing number of abnormal DNA genotypes caused by chromosomal abnormalities have been revealed in cases of individual identification and sex-typing analysis, especially analyses of the amelogenin and short tandem repeat (STR) loci on the sex chromosomes. Here, we report a 17-year-old female with Turner syndrome typed as male due to the presence of the amelogenin Y allele. The Y-STR haplotype showed allele dropout of three Y-STR loci (DYS549, DYS392 and DYS448). Further examination showed that the proband's karyotype was 45,X/46,X,del(Y) (q11.23), and the deletion of the Yp11.2 region was confirmed to encompass the observed microdeletion of the azoospermia factor (AZF)b + c region. One challenge in forensics is inaccurate sex typing of individuals at the molecular level, particularly for individuals with chromosomal abnormalities. This case suggests that various medical evaluations, including the examination of sex-related manifestations, karyotypes, and clinical phenotypes of individuals, along with the detection of sex-typing gene markers will be beneficial to overcome the issues caused by cytogenetic disorders of the sex chromosomes.

Organoids from human tooth showing epithelial stemness phenotype and differentiation potential

Insight into human tooth epithelial stem cells and their biology is sparse. Tissue-derived organoid models typically replicate the tissue’s epithelial stem cell compartment. Here, we developed a first-in-time epithelial organoid model starting from human tooth. Dental follicle (DF) tissue, isolated from unerupted wisdom teeth, efficiently generated epithelial organoids that were long-term expandable. The organoids displayed a tooth epithelial stemness phenotype similar to the DF’s epithelial cell rests of Malassez (ERM), a compartment containing dental epithelial stem cells. Single-cell transcriptomics reinforced this organoid-ERM congruence, and uncovered novel, mouse-mirroring stem cell features. Exposure of the organoids to epidermal growth factor induced transient proliferation and eventual epithelial-mesenchymal transition, highly mimicking events taking place in the ERM in vivo. Moreover, the ERM stemness organoids were able to unfold an ameloblast differentiation process, further enhanced by transforming growth factor-β (TGFβ) and abrogated by TGFβ receptor inhibition, thereby reproducing TGFβ's known key position in amelogenesis. Interestingly, by creating a mesenchymal-epithelial composite organoid (assembloid) model, we demonstrated that the presence of dental mesenchymal cells (i.e. pulp stem cells) triggered ameloblast differentiation in the epithelial stem cells, thus replicating the known importance of mesenchyme-epithelium interaction in tooth development and amelogenesis. Also here, differentiation was abrogated by TGFβ receptor inhibition. Together, we developed novel organoid models empowering the exploration of human tooth epithelial stem cell biology and function as well as their interplay with dental mesenchyme, all at present only poorly defined in humans. Moreover, the new models may pave the way to future tooth-regenerative perspectives.

Analysis of the cells isolated from epithelial cell rests of Malassez through single-cell limiting dilution

The epithelial cell rests of Malassez (ERM) are essential in preventing ankylosis between the alveolar bone and the tooth (dentoalveolar ankylosis). Despite extensive research, the mechanism by which ERM cells suppress ankylosis remains uncertain; perhaps its varied population is to reason. Therefore, in this study, eighteen unique clones of ERM (CRUDE) were isolated using the single-cell limiting dilution and designated as ERM 1-18. qRT-PCR, ELISA, and western blot analyses revealed that ERM-2 and -3 had the highest and lowest amelogenin expression, respectively. Mineralization of human periodontal ligament fibroblasts (HPDLF) was reduced in vitro co-culture with CRUDE ERM, ERM-2, and -3 cells, but recovered when an anti-amelogenin antibody was introduced. Transplanted rat molars grown in ERM-2 cell supernatants produced substantially less bone than those cultured in other cell supernatants; inhibition was rescued when an anti-amelogenin antibody was added to the supernatants. Anti-Osterix antibody staining was used to confirm the development of new bones. In addition, next-generation sequencing (NGS) data were analysed to discover genes related to the distinct roles of CRUDE ERM, ERM-2, and ERM-3. According to this study, amelogenin produced by ERM cells helps to prevent dentoalveolar ankylosis and maintain periodontal ligament (PDL) space, depending on their clonal diversity.

Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review

Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.

Molecular analysis for sex determination in forensic dentistry: a systematic review

Background

Sex determination can be useful in forensic casework, such as in mass disasters, transportation accidents, and cases of a missing person or sexual assault. The remnants of the body can be traced by DNA of the victim, using samples from various sources such as teeth, oral epithelial tissue, and saliva.

Main body

The review aimed to describe research in forensic dentistry with DNA source from the oral region and methods of the applied DNA analysis. A search in PubMed, Google Scholar, and Scopus electronic databases from 2009 to 2019 was conducted to include studies according to PRISMA guidelines. Ten studies were eligible for the review. Genetic markers originated from dentin, dental pulp, saliva, or epithelial cells from buccal tissue and prosthesis. The applied DNA analysis methods were PCR, real-time PCR, and nested PCR.

Conclusions

The published articles mostly showed successful DNA extraction and sex determination, but the rate of success declined as the sample source underwent manipulation to mimic the forensic conditions. Amelogenin, SRY, and DYS14 were reliable indicators for sex determination. Molecular analysis has proved to be efficient and accurate, but the daily forensic practice must select the most appropriate method according to the available body remnants.

Preclinical and Clinical Applications of Biomaterials in the Enhancement of Wound Healing in Oral Surgery: An Overview of the Available Reviews

Oral surgery has undergone dramatic developments in recent years due to the use of biomaterials. The aim of the present review is to provide a general overview of the current biomaterials used in oral surgery and to comprehensively outline their impact on post-operative wound healing. A search in Medline was performed, including hand searching. Combinations of searching terms and several criteria were applied for study identification, selection, and inclusion. The literature was searched for reviews published up to July 2020. Reviews evaluating the clinical and histological effects of biomaterials on post-operative wound healing in oral surgical procedures were included. Review selection was performed by two independent reviewers. Disagreements were resolved by a third reviewer, and 41 reviews were included in the final selection. The selected papers covered a wide range of biomaterials such as stem cells, bone grafts, and growth factors. Bioengineering and biomaterials development represent one of the most promising perspectives for the future of oral surgery. In particular, stem cells and growth factors are polarizing the focus of this ever-evolving field, continuously improving standard surgical techniques, and granting access to new approaches.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.

Genetic polymorphisms influence shear bond resistance of orthodontic brackets

OBJECTIVES

The purpose of this study was to determine if shear bond resistance of orthodontic brackets bonded to enamel is associated with genes implicated in the enamel mineralization process.

METHODS

Ninety-two permanent, caries-free premolars extracted for orthodontic purposes and their associated saliva samples were obtained. Eighteen single nucleotide polymorphisms (SNPs) were studied for association with shear bond resistance. The genes of interest in this study were those previously associated with dental caries by our group. All tooth samples were bonded on the buccal surface with metallic lower lateral brackets, and then subjected to physical debonding. The force required to debond the bracket was recorded in Newtons (N) and converted to a shear bond resistance value in Megapascals (N/mm²). The data were analyzed for statistical significance as compared with the mean shear bond resistance value via PLINK whole genome analysis software.

RESULTS

Associations were found between the SNPs for tuftelin (rs7526319, P = 0.004) and amelogenin (rs17878486, P = 0.04) and a higher shear bond resistance.

CONCLUSION

The collected data support the proposed hypothesis that genes involved in the mineralization process affect the bonding of orthodontic brackets, and such an association is of value for the field of orthodontics, particularly in evaluating the efficacy of enamel-resin bond strength for patients receiving treatment.

Toward Preventing Enamel Hypoplasia: Modeling Maternal and Neonatal Biomarkers of Human Calcium Homeostasis

AIM

The aim of this study was to assess biomarkers of calcium homeostasis and tooth development, in mothers during pregnancy and their children at birth, for enamel hypoplasia (EH) in the primary maxillary central incisor teeth.

METHODS

Bayesian methodology was used for secondary data analyses from a randomized, controlled trial of prenatal vitamin D3 supplementation in healthy mothers (N = 350) and a follow-up study of a subset of the children. The biomarkers were serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), total circulating 25-dihydroxyvitamin D (25(OH)D), and 1,25-dihydroxyvitamin D (1,25(OH)2D). The maternal biomarkers were assayed monthly during pregnancy, and the child's biomarkers were derived from cord blood. Digital images of the child's 2 teeth were scored for EH using Enamel Defects Index criteria for each of the incisal, middle, and cervical regions for an EH extent score.

RESULTS

The child EH prevalence was 41% (60/145), with most defects present in the incisal and middle tooth regions. Cord blood iPTH and 1,25(OH)2D levels were significantly associated with EH extent after controlling for maternal factors. For every 1 pg/mL increase in cord blood iPTH, the EH extent decreased by approximately 6%. For every 10 pg/mL increase in cord blood 1,25(OH)2D, the EH extent increased by almost 30% (holding all other terms constant and adjusting for subject-level heterogeneity). The relationship between maternal 25(OH)D and maternal mean iPTH varied significantly by EH extent.

CONCLUSION

The results suggest possible modifiable relationships of maternal and neonatal factors of calcium homeostasis during pregnancy and at birth for EH, contributing to the frontier of knowledge regarding sound tooth development for dental caries prevention.

Novel LRAP-binding partner revealing the plasminogen activation system as a regulator of cementoblast differentiation and mineral nodule formation in vitro

Amelogenin isoforms, including full-length amelogenin (AMEL) and leucine-rich amelogenin peptide (LRAP), are major components of the enamel matrix, and are considered as signaling molecules in epithelial-mesenchymal interactions regulating tooth development and periodontal regeneration. Nevertheless, the molecular mechanisms involved are still poorly understood. The aim of the present study was to identify novel binding partners for amelogenin isoforms in the cementoblast (OCCM-30), using an affinity purification assay (GST pull-down) followed by mass spectrometry and immunoblotting. Protein-protein interaction analysis for AMEL and LRAP evidenced the plasminogen activation system (PAS) as a potential player regulating OCCM-30 response to amelogenin isoforms. For functional assays, PAS was either activated (plasmin) or inhibited (ε-aminocaproic acid [aminocaproic]) in OCCM-30 cells and the cell morphology, mineral nodule formation, and gene expression were assessed. PAS inhibition (EACA 100 mM) dramatically decreased mineral nodule formation and expression of OCCM-30 differentiation markers, including osteocalcin (Bglap), bone sialoprotein (Ibsp), osteopontin (Spp1), tissue-nonspecific alkaline phosphatase (Alpl) and collagen type I (Col1a1), and had no effect on runt-related transcription factor 2 (Runx2) and Osterix (Osx) mRNA levels. PAS activation (plasmin 5 µg/µl) significantly increased Col1a1 and decreased Bglap mRNA levels (p < .05). Together, our findings shed new light on the potential role of plasminogen signaling pathway in the control of the amelogenin isoform-mediated response in cementoblasts and provide new insights into the development of targeted therapies.

A Review of the Role of Amelogenin Protein in Enamel Formation and Novel Experimental Techniques to Study its Function

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Amelognein protein plays a vital role in the formation and mineralization of enamel matrix. Amelogenin structure is complex in nature and researchers have studied it with different experimental techniques. Considering its important role, there is a need to understand this important protein, which has been discussed in detail in this review. In addition, various experimental techniques to study amelogenin protein used previously have been tackled along with their advantages and disadvantages. A selection of 67 relevant articles/book chapters was included in this study. The review concluded that amelogenins act as nanospheres or spacers for the growth of enamel crystals. Various experimental techniques can be used to study amelogenins, however, their advantages and drawbacks should be kept in mind before performing analysis.

Enamel peptides reveal the sex of the Late Antique 'Lovers of Modena'

Recent work has disclosed the critical role played by enamel peptides in sex classification of old skeletal remains. In particular, protein AMELY (amelogenin isoform Y) is present in the enamel dental tissue of male individuals only, while AMELX (isoform X) can be found in both sexes. AMELY can be easily detected by LC-MS/MS in the ion extracted chromatograms of the SM(ox)IRPPY peptide (monoisotopic [M + 2 H]+2 mass = 440.2233 m/z). In this paper, we exploited the dimorphic features of the amelogenin protein to determine the sex of the so-called 'Lovers of Modena', two Late Antique individuals whose skeletons were intentionally buried hand-in-hand. Upon discovery, mass media had immediately assumed they were a male-female couple, even if bad preservation of the bones did not allow an effective sex classification. We were able to extract proteins from the dental enamel of both individuals (~1600 years old) and to confidently classify them as males. Results were compared to 14 modern and archaeological control samples, confirming the reliability of the ion chromatogram method for sex determination. Although we currently have no information on the actual relationship between the 'Lovers of Modena' (affective? Kin-based?), the discovery of two adult males intentionally buried hand-in-hand may have profound implications for our understanding of funerary practices in Late Antique Italy.

Remineralization, Regeneration, and Repair of Natural Tooth Structure: Influences on the Future of Restorative Dentistry Practice

Currently, the principal strategy for the treatment of carious defects involves cavity preparations followed by the restoration of natural tooth structure with a synthetic material of inferior biomechanical and esthetic qualities and with questionable long-term clinical reliability of the interfacial bonds. Consequently, prevention and minimally invasive dentistry are considered basic approaches for the preservation of sound tooth structure. Moreover, conventional periodontal therapies do not always ensure predictable outcomes or completely restore the integrity of the periodontal ligament complex that has been lost due to periodontitis. Much effort and comprehensive research have been undertaken to mimic the natural development and biomineralization of teeth to regenerate and repair natural hard dental tissues and restore the integrity of the periodontium. Regeneration of the dentin-pulp tissue has faced several challenges, starting with the basic concerns of clinical applicability. Recent technologies and multidisciplinary approaches in tissue engineering and nanotechnology, as well as the use of modern strategies for stem cell recruitment, synthesis of effective biodegradable scaffolds, molecular signaling, gene therapy, and 3D bioprinting, have resulted in impressive outcomes that may revolutionize the practice of restorative dentistry. This Review covers the current approaches and technologies for remineralization, regeneration, and repair of natural tooth structure.

Generation of Amelx-iCre Mice Supports Ameloblast-Specific Role for Stim1

The identification and targeting of the molecular pathways regulating amelogenesis is an ongoing challenge in dental research, and progress has been restricted by the limited number of genetic tools available to study gene function in ameloblasts. Here, we generated 4 transgenic Cre-driver mouse lines that express improved Cre (iCre)-recombinase from the locus of the mouse ameloblast-specific gene amelogenin X (Amelx-iCre) with a large (250-kb) bacterial artificial chromosome DNA vector. All 4 Amelx-iCre transgenic lines were bred with ROSA26 reporter mice to characterize the iCre developmental pattern with the LacZ gene encoding β-galactosidase enzyme activity assay and Cre protein immunohistochemistry. From the 4 generated transgenic lines, 2 were selected for further analysis because they expressed a high amount of Cre recombinase exclusively in ameloblasts and showed developmental stage- and cell-specific β-galactosidase activity mimicking the endogenous amelogenin expression. To test the functionality of the selected transgenic models, we bred the 2 Amelx-iCre mice lines with stromal interaction molecule 1 (Stim1) floxed mice to generate ameloblast-specific Stim1 conditional knockout mice (Stim1 cKO). STIM1 protein serves as one of the main calcium sensors in ameloblasts and plays a major role in enamel mineralization and ameloblast differentiation. Amelx-iCre mice displayed exclusive CRE-mediated recombination in incisor and molar ameloblasts. Stim1 cKO mice showed a severely defected enamel phenotype, including reduced structural integrity concomitant with increased attrition and smaller teeth. The phenotype and genotype of the Amelx-iCre/Stim1 cKO showed significant differences with the previously reported Ker14-Cre/Stim1 cKO, highlighting the need for cell- and stage-specific Cre lines for an accurate phenotype-genotype comparison. Furthermore, our model has the advantage of carrying the entire Amelx gene locus rather than being limited to an Amelx partial promoter construct, which greatly enhances the stability and the specificity of our Cre expression. As such, the Amelx-iCre transgenic lines that we developed may serve as a powerful tool for targeting ameloblast-specific gene expression in future investigations.

A Novel AMELX Mutation, Its Phenotypic Features, and Skewed X Inactivation

Amelogenesis imperfecta (AI) is a group of genetic disorders of defective dental enamel. Mutation of AMELX encoding amelogenin on the X chromosome is a major cause of AI. Here we report a Chinese family with hypoplastic and hypomineralized AI. Whole exome analysis revealed a novel mutation c.185delC in exon 5 of AMELX causing the frame shift p.Pro62ArgfsTer47 (or p.Pro62Argfs*47). By sequencing of polymerase chain reaction products and T-vector clones, the mutation was confirmed as homozygous in the proband, hemizygous in her father, and heterozygous in her mother. The proband and her father had small and yellowish teeth with thin and rough enamel that was radiographically indistinguishable from the underlying dentin. Scanning electronic microscopy of 1 maternal tooth showed cracks and exposed loosely packed enamel prisms in affected areas. Consistent with a 25:75 skewing of X inactivation in the peripheral blood DNA as measured by androgen receptor allele methylation, the surface of the mother’s tooth had alternating vertical ridges of transparent normal and white chalky enamel in a 34:66 ratio. In summary, this study provides one of the few phenotypic comparisons of hemizygous and homozygous AMELX mutations and suggests that the skewing of X inactivation in AI contributes to the phenotypic variations in heterozygous carriers of X-linked AI.

Sex determination by amplification of amelogenin gene from dental pulp tissue by polymerase Chain Reaction

Introduction

Forensic odontology necessarily involves the application of dentistry along with various other branches of sciences which deals with proper handling, examination, evaluation, and presentation of dental evidences, that aids to investigate a crime and deliver justice. Sex determination is a part of forensic odontology and an essential priority when traditional identification of the deceased becomes impossible.

Aim

To determine Sex by analysis of the Amelogenin gene using Polymerase Chain Reaction (PCR) method on Deoxyribose nucleic acid (DNA) isolated from dental pulp, which was exposed to various environmental conditions created artificially to mimic a forensic scenario.

Materials and Method

This in-vitro study was conducted by subjecting extracted teeth to various conditions imitating a forensic scene, viz. desiccation at room temperatures, immersion in salt water, burial in soil and even exposing to extremes of temperatures. DNA was extracted from dental pulp tissue and sex determination was achieved by amplification of the amelogenin gene through AMEL gene based primers in PCR.

Result

Among all the samples used in this study, DNA could be extracted from all, except from those that were subjected to a temperature of 350 °C. DNA amplification and sex determination of the samples were found to be accurate when compared to sex of the individual which was recorded initially, during collection of teeth samples.

Conclusion

This study shows teeth to be a potent source of DNA even in extreme environmental conditions, barring high temperatures and determination of sex by PCR amplification of AMEL markers to be quite reliable.

The evaluation of zinc and copper content in tooth enamel without any pathological changes - an in vitro study

Objectives

The objectives of the study were to evaluate the content of copper and zinc in individual layers of tooth enamel and to analyze the relationships between the study minerals in individual layers of tooth enamel.

Patients and methods

Fifteen human permanent teeth were cut off every 150 μm alongside the labial surface. Acid biopsy of each layer was performed. The zinc content was determined using the air-acetylene flame method. The copper content was determined using the electrothermal technique with argon.

Results

The mean zinc concentrations increased significantly starting from the outer enamel surface, with the maximum concentration in the 150-300 μm layer. The mean copper concentrations increased substantially from the outer enamel surface to a depth of 150 μm, and then a slight downward trend of this mineral levels was seen, down to a depth of 450 μm. Strong positive correlation was found between the zinc and copper concentrations at depths of 150-300, 450-600 and 600-750 μm.

Conclusion

The levels of zinc and copper in the outer enamel layers may have an effect on the increased content of unipolar minerals at deeper enamel layers. The content of the study elements determined may reflect the process of mineralization and maturation of enamel in the pre-eruption period.

When forensic odontology met biochemistry: Multidisciplinary approach in forensic human identification

When human remains are found, the priority of the investigation is to ascertain the identity of the deceased. A positive identification is a key factor in providing closure for the family of the deceased; it is also required to issue the death certificate and therefore, to settle legal affairs. Moreover, it is difficult for any forensic investigation involving human remains to be solved without the determination of an identity. Therefore, personal identification is necessary for social, legal and forensic reasons. In the last thirty years forensic odontology has experienced an important transformation, from primarily involving occasional dental identification into a broader role, contributing to the determination of the biological profile. In the same way, "DNA fingerprinting" has evolved not only in terms of improving its technology, but also in its application beyond the "classical": helping with the estimation of sex, age and ancestry. As these two forensic disciplines have developed independently, their pathways have crossed several times through human identification operations, especially the ones that require a multidisciplinary approach. Thus, the aim of this review is to describe the contributions of both forensic odontology and molecular biology/biochemistry to human identification, demonstrating how a multidisciplinary approach can lead to a better and more efficient identification.

DNA isolation from teeth by organic extraction and identification of sex of the individual by analyzing the AMEL gene marker using PCR

BACKGROUND

To identify the sex of the deceased individual from dental hard tissue such as enamel and dentine.

OBJECTIVE

To isolate the DNA from dental hard tissue (enamel and dentin) from teeth extracted for prophylactic purpose, to assess the quality and purity of DNA and to identify the sex using polymerized chain reactor (PCR).

MATERIALS AND METHODS

DNA was extracted following phenol/chloroform (organic) extraction from 20 male and 20 female teeth. The samples that contain the amelogenin gene (amel) were amplified by PCR. The products of the PCR were run on agarose gel with ethidium bromide staining on gel documentation system.

RESULTS

The results on the gel showed the presence of X-specific bands at 212 bp and Y-specific bands at 218 bp. Males were distinguished from females by the presence of two bands whereas female samples showed only one, that is, X-specific band on the gel. The gender from the known samples was determined with complete accuracy, and the results were analyzed statistically by the Chi-square test.

CONCLUSION

In our study, the PCR-based method showed 100% specificity and sensitivity.

Sex determination from dentin and pulp in a medicolegal context

BACKGROUND

The techniques used to determine the sex of skeletons are limited. The authors conducted a study to analyze the accuracy of sex identification from dentin and pulp via DNA isolation.

METHODS

The authors extracted DNA from the dentin and pulp of 14 teeth by using a silica-based methodology. They used the amelogenin gene to determine the sex via polymerase chain reaction. β-actin, a housekeeping gene, was used as a control gene. The authors checked the results in agarose gel and semiquantified them by using gel analysis software.

RESULTS

The DNA yield depended on the type of tooth and was lowest in the smallest teeth (that is, incisors). In all cases, the authors were able to identify the sex, as well as the control gene, which suggests the potential to identify other genes, such as short tandem repeats.

CONCLUSIONS

It is possible to correctly identify a person's sex from dentin and pulp; in instances in which one dental material is not available, the other material can be used with the same efficiency. Practical Implications. The results of this study are applicable to forensic dentistry, particularly in situations in which there is commingling of remains and fragmentary remains, and there may be only one tooth with which to identify a person's sex.

Three-dimensional printed multiphase scaffolds for regeneration of periodontium complex

Tooth-supporting periodontium forms a complex with multiple tissues, including cementum, periodontal ligament (PDL), and alveolar bone. In this study, we developed multiphase region-specific microscaffolds with spatiotemporal delivery of bioactive cues for integrated periodontium regeneration. Polycarprolactione-hydroxylapatite (90:10 wt%) scaffolds were fabricated using three-dimensional printing seamlessly in three phases: 100-μm microchannels in Phase A designed for cementum/dentin interface, 600-μm microchannels in Phase B designed for the PDL, and 300-μm microchannels in Phase C designed for alveolar bone. Recombinant human amelogenin, connective tissue growth factor, and bone morphogenetic protein-2 were spatially delivered and time-released in Phases A, B, and C, respectively. Upon 4-week in vitro incubation separately with dental pulp stem/progenitor cells (DPSCs), PDL stem/progenitor cells (PDLSCs), or alveolar bone stem/progenitor cells (ABSCs), distinctive tissue phenotypes were formed with collagen I-rich fibers especially by PDLSCs and mineralized tissues by DPSCs, PDLSCs, and ABSCs. DPSC-seeded multiphase scaffolds upon in vivo implantation yielded aligned PDL-like collagen fibers that inserted into bone sialoprotein-positive bone-like tissue and putative cementum matrix protein 1-positive/dentin sialophosphoprotein-positive dentin/cementum tissues. These findings illustrate a strategy for the regeneration of multiphase periodontal tissues by spatiotemporal delivery of multiple proteins. A single stem/progenitor cell population appears to differentiate into putative dentin/cementum, PDL, and alveolar bone complex by scaffold's biophysical properties and spatially released bioactive cues.