Regulatory role of transforming growth factor-beta, bone morphogenetic protein-2, and protein-4 on gene expression of extracellular matrix proteins and differentiation of dental pulp cells

The expression of developmental stage-specific genes during pulp cell differentiation into preodontoblasts was examined in bovine adult pulp cell culture. When proliferation was down-regulated after 14 days of primary culture, expression of fibronectin and type I and type III collagen mRNAs was increased. Expression of alkaline phosphatase was gradually increased, and mRNA for osteocalcin, a marker of preodontoblast, appeared just before the onset of mineralization. Contrarily, in expanded culture, the expression of mRNA for the extracellular matrix proteins was gradually increased from the beginning of culture up to Day 28. Similarly, mRNA levels of alkaline phosphatase and osteocalcin were also increased gradually. Expression of TGF-beta 1 mRNA disappeared on Day 21 in the primary culture when expression of alkaline phosphatase mRNA was increased. BMP-4 mRNA was expressed on Day 14 when the expression of the extracellular matrix proteins was increased. BMP-2 mRNA was expressed on Day 28 when osteocalcin appeared. Recombinant TGF-beta 1 inhibited alkaline phosphatase activity, while BMP-2 and BMP-4 stimulated it. BMP-4 increased expression of alpha 1(I) collagen mRNA, and BMP-2 increased osteocalcin synthesis. These results demonstrate the regulatory role of these TGF-beta superfamily members on the gene expression of extracellular matrix proteins and the differentiation of pulp cells into preodontoblasts.

Age-related changes of the dental pulp complex and their relationship to systemic aging

The dental pulp and its associated structures, the dentin and the cementum, are discussed. Because many of the age-related pulpal changes have components considered in several of the current theories of aging, these theories are briefly reviewed. Part 2 describes the age-related changes of the dental pulp, the dentin, and the cementum (the dental pulp complex). An attempt is made to differentiate inherent aging changes from physiologic defensive changes and pathologic irritant-induced changes. Part 3 describes the relationship of age-induced changes in the dental pulp complex to components of the current aging theories together with a unified concept of the dental pulp complex aging. Part 4 considers whether dental pulp complex aging can be used as a biomarker for generalized aging. Whether age-related changes of the dental pulp complex can be altered by interventions is discussed.

Teeth and tooth nerves

(1) Although our knowledge on teeth and tooth nerves has increased substantially during the past 25 years, several important issues remain to be fully elucidated. As a result of the work now going on at many laboratories over the world, we can expect exciting new findings and major break-throughs in these and other areas in a near future. (2) Dentin-like and enamel-like hard tissues evolved as components of the exoskeletal bony armor of early vertebrates, 500 million years ago, long before the first appearance of teeth. It is possible that teeth developed from tubercles (odontodes) in the bony armor. The presence of a canal system in the bony plates, of tubular dentin, of external pores in the enamel layer and of a link to the lateral line system promoted hypotheses that the bony plates and tooth precursors may have had a sensory function. The evolution of an efficient brain, of a head with paired sense organs and of toothed jaws concurred with a shift from a sessile filter-feeding life to active prey hunting. (3) The wide spectrum of feeding behaviors exhibited by modern vertebrates is reflected by a variety of dentition types. While the teeth are continuously renewed in toothed non-mammalian vertebrates, tooth turnover is highly restricted in mammals. As a rule, one set of primary teeth is replaced by one set of permanent teeth. Since teeth are richly innervated, the turnover necessitates a local neural plasticity. Another factor calling for a local plasticity is the relatively frequent occurrence of age-related and pathological dental changes. (4) Tooth development is initiated through interactions between the oral epithelium and underlying neural crest-derived mesenchymal cells. The interactions are mediated by cell surface molecules, extracellular matrix molecules and soluble molecules. The possibility that the initiating events might involve a neural component has been much discussed. With respect to mammals, the experimental evidence available does not support this hypothesis. In the teleost Tilapia mariae, on the other hand, tooth germ formation is interrupted, and tooth turnover ceases after local denervation. (5) Prospective dental nerves enter the jaws well before onset of tooth development. When a dental lamina has formed, a plexus of nerve branches is seen in the subepithelial mesenchyme. Shortly thereafter, specific branches to individual tooth primordia can be distinguished. In bud stage tooth germs, axon terminals surround the condensed mesenchyme and in cap stage primordia axons grow into the dental follicle.(ABSTRACT TRUNCATED AT 400 WORDS)

Induction of reparative dentin formation by ultrasound-mediated gene delivery of growth/differentiation factor 11

Bone morphogenetic proteins (BMPs) are morphogens implicated in embryonic and regenerative odontogenic differentiation. Gene therapy has the potential to induce reparative dentin formation for potential pulp capping. We have optimized the gene transfer of Growth/differentiation factor 11 (Gdf11)/Bmp11 plasmid DNA into dental pulp stem cells by sonoporation in vivo. Dental pulp tissue treated with plasmid pEGFP or CMV-LacZ in 5-10% Optison (Molecular Biosystems Inc., San Diego, CA) and stimulated by ultrasound (1 MHz, 0.5 W/cm(2), 30 sec) showed significant efficiency of gene transfer and high level of protein production selectively in the local region, within 500 microm of the amputated site of the pulp tissue. The Gdf11 cDNA plasmid transferred into dental pulp tissue by sonoporation in vitro, induced the expression of dentin sialoprotein (Dsp), a differentiation marker for odontoblasts. The transfection of Gdf11 by sonoporation stimulated a large amount of reparative dentin formation on the amputated dental pulp in canine teeth in vivo. These results suggest the possible use of BMPs using ultrasound-mediated gene therapy for endodontic dental treatment.

Immunohistochemical demonstration of amelogenin penetration toward the dental pulp in the early stages of ameloblast development in rat molar tooth germs

In order to examine the synthesis and secretion of enamel protein by ameloblasts in their early stages of development, immunohistochemical localization was carried out at light and electron microscopic levels using a monoclonal antibody produced in a preliminary experiment. Materials used were tooth germs of mandibular first molars of rats at 0-5 days after birth. Immunoblot analysis after two-dimensional electrophoresis revealed that antigen molecules recognized by the monoclonal antibody were amelogenins of 26-28 kDa (pI, 6.6-7.0). An immunohistochemical examination using this monoclonal antibody demonstrated that the presecretory ameloblasts in their early stages of differentiation both synthesized amelogenin and secreted through a classical merocrine secretory pathway. In some presecretory ameloblasts as well as ameloblasts we observed the distended cisternae of rough endoplasmic reticulum (rER) which demonstrated heterogenous immunolabelling. The immunolabellings were also detected in the predentin as well as the intercellular spaces of odontoblasts and dental pulp cells which indicated penetration of amelogenin from the presecretory ameloblast layer to the dental pulp. The presence of coated pits at the plasma membrane of odontoblasts in close proximity to enamel protein along with the immunolabelling of lysosomes of the odontoblasts suggests the phagocytosis of the enamel protein into the odontoblasts. These observations suggest the possibility that the penetration of enamel protein toward the dental pulp and odontoblasts plays a role in the interaction between ameloblasts and odontoblasts.

Establishment of primary cultures of pulp cells from bovine permanent incisors

A primary culture method was established by comparing the different effects of four methods of enzymatic separation--trypsin, collagenase with and without trypsin pretreatment, and a trypsin-collagenase mixture--and five media: DMEM, DMEM and Ham's F 12 mixture, F 12, RPMI 1640 and Medium 199. The trypsin pretreatment/collagenase method was most preferable considering the high number of isolated cells, satisfactory adhesion, good growth and a single population at subconfluence. DMEM and the DMEM/F-12 mixture resulted in the best adhesion, cell growth and cell number at confluence. Primary cells separated by the trypsin pretreatment/collagenase method and cultured in DMEM were responsive to parathyroid hormone at the proliferating stage and had higher alkaline phosphatase activity than cells cultured from gingiva and mucosa after reaching confluence. The long-term cultured cells formed nodules that were slightly mineralized. These results indicate that the cultured pulp cells had properties characteristic of pulp cells in vivo. This enzymatic separation method may be useful in studies of the regulation of pulp metabolism and odontoblast differentiation.

Characterization and gene expression of high conductance calcium-activated potassium channels displaying mechanosensitivity in human odontoblasts

Odontoblasts form a layer of cells responsible for the dentin formation and possibly mediate early stages of sensory processing in teeth. Several classes of ion channels have previously been identified in the odontoblast or pulp cell membrane, and it is suspected that these channels assist in these events. This study was carried out to characterize the K(Ca) channels on odontoblasts fully differentiated in vitro using the patch clamp technique and to investigate the HSLO gene expression encoding the alpha-subunit of these channels on odontoblasts in vivo. In inside-out patches, K(Ca) channels were identified on the basis of their K(+) selectivity, conductance, voltage, and Ca(2+) dependence. In cell-attached patches, these channels were found to be activated by application of a negative pressure as well as an osmotic shock. By reverse transcription-polymerase chain reaction, a probe complementary to K(Ca) alpha-subunit mRNA was constructed and used for in situ hybridization on human dental pulp samples. Transcripts were expressed in the odontoblast layer. The use of antibodies showed that the K(Ca) channels were preferentially detected at the apical pole of the odontoblasts. These channels could be involved in mineralization processes. Their mechanosensitivity suggests that the fluid displacement within dentinal tubules could be transduced into electrical cell signals.

Sonic Hedgehog Signaling and Tooth Development

Sonic hedgehog (Shh) is a secreted protein with important roles in mammalian embryogenesis. During tooth development, Shh is primarily expressed in the dental epithelium, from initiation to the root formation stages. A number of studies have analyzed the function of Shh signaling at different stages of tooth development and have revealed that Shh signaling regulates the formation of various tooth components, including enamel, dentin, cementum, and other soft tissues. In addition, dental mesenchymal cells positive for Gli1, a downstream transcription factor of Shh signaling, have been found to have stem cell properties, including multipotency and the ability to self-renew. Indeed, Gli1-positive cells in mature teeth appear to contribute to the regeneration of dental pulp and periodontal tissues. In this review, we provide an overview of recent advances related to the role of Shh signaling in tooth development, as well as the contribution of this pathway to tooth homeostasis and regeneration.

Expression of the small leucine-rich proteoglycan osteoadherin/osteomodulin in human dental pulp and developing rat teeth

Because the extracellular matrices of dentin and bone are composed mainly of type I collagen, their characteristics are determined by the nature of noncollagenous proteins (NCPs). Among these NCPs, some proteoglycans (PGs) belong to the small leucine-rich proteoglycans (SLRPs). Recently, osteoadherin (OSAD) has been described as a new member of this family, that is expressed by mature bovine osteoblasts. Here, we report the expression of OSAD messenger RNA (mRNA) in human dental tissues and during the development of rat molars, using in situ hybridization. For this purpose, we constructed a probe for OSAD mRNA transcripts from human odontoblast cells cultured in vitro. Our results indicate that the mature human odontoblasts overexpress the OSAD gene as compared with cells present in the pulp core. In rat developing molars, mRNA transcripts were first detected in alveolar bone in 19-day-old embryos. At the same age, no signal was detected in any cell of the first molar. In more mature teeth (newborn and 2-day-old rats), OSAD expression starts in the polarized odontoblasts and increases in the secretory and mature odontoblasts, respectively. Interestingly, a similar pattern of expression was observed in the ameloblast layer responsible for the deposition of enamel mineralized matrix. Together, these results lead us to speculate that OSAD may be implicated in biomineralization processes.

Expression of clock proteins in developing tooth

Morphological and functional changes during ameloblast and odontoblast differentiation suggest that enamel and dentin formation is under circadian control. Circadian rhythms are endogenous self-sustained oscillations with periods of 24h that control diverse physiological and metabolic processes. Mammalian clock genes play a key role in synchronizing circadian functions in many organs. However, close to nothing is known on clock genes expression during tooth development. In this work, we investigated the expression of four clock genes during tooth development. Our results showed that circadian clock genes Bmal1, clock, per1, and per2 mRNAs were detected in teeth by RT-PCR. Immunohistochemistry showed that clock protein expression was first detected in teeth at the bell stage (E17), being expressed in EOE and dental papilla cells. At post-natal day four (PN4), all four clock proteins continued to be expressed in teeth but with different intensities, being strongly expressed within the nucleus of ameloblasts and odontoblasts and down-regulated in dental pulp cells. Interestingly, at PN21 incisor, expression of clock proteins was down-regulated in odontoblasts of the crown-analogue side but expression was persisting in root-analogue side odontoblasts. In contrast, both crown and root odontoblasts were strongly stained for all four clock proteins in first molars at PN21. Within the periodontal ligament (PDL) space, epithelial rests of Malassez (ERM) showed the strongest expression among other PDL cells. Our data suggests that clock genes might be involved in the regulation of ameloblast and odontoblast functions, such as enamel and dentin protein secretion and matrix mineralization.

Expression of TGF-beta superfamily receptors in dental pulp

Transforming growth factor-beta (TGF-beta) superfamily members and their cell-surface receptors may play inductive and/or regulatory roles in tooth development and repair. It will be important to identify the complete set of TGF-beta superfamily receptors, to examine their temporal and spatial localization during tooth development, and to elucidate the cascade of molecular events of tooth formation induced by the TGF-beta superfamily. In this report, we have cloned the cDNAs encoding potential receptors for TGF-beta superfamily members in rat incisor pulp and bovine adult pulp which are regarded as embryonic and adult pulp, respectively. We analyzed poly (A)+ RNA from rat incisor pulp and bovine adult pulp by reverse-transcriptase/polymerase chain-reaction (RT-PCR), using a degenerate primers corresponding to the most conserved amino acid sequences in the intracellular serine/threonine kinase of type I or type II like kinase-1 (ALK-1), ALK-2, ALK-3 (bone morphogenetic protein receptor type IA, BMPR-IA), ALK-4 (B1), ALK-5, ALK-6 (BMPR-IB), and BMPR-II (BMP type II receptor) was found to be in dental pulp. Northern blot analysis further detected TGF-beta type II receptor (T beta R-II) mRNA transcript in addition to the above-identified receptors. These results provide the first evidence of multiple type I and type II receptors for TGF-beta s, activins, and BMPs expressed in embryonic and adult pulp, implicating diverse function in tooth development and pulp tissue repair.

Age estimation using canine pulp volumes in adults: a CBCT image analysis

Secondary dentine deposition is responsible for the decrease in the volume of the pulp cavity with age. Therefore, the volume of the pulp cavity can be considered as a predictor for estimating age. The aims of this study were to investigate the relationship strength between canine pulp volumes and chronological age from homogenous (approximately equal numbers of individuals in each age range) age distribution and to assess the effect of sex as predictor in age estimation. This study was performed on 719 subjects of Pakistani origin. Cone beam computed tomography images of 521 left maxillary and 681 left mandibular canines were collected from 368 females and 349 males aged from 15 to 65 years. Planmeca Romexis® software was used to trace the outline of the pulp cavity and to calculate pulp volumes. Regression analysis was performed to assess the correlation between pulp volumes considering with and without sex as a predictor with chronological age. The obtained results showed that mandibular canine pulp volume and sex have the highest predictive power (R² = 0.33). The relationship between mandibular canine pulp volume and sex with chronological age demonstrates an odd S-shaped non-linear relationship. A statistically significant difference in volumes of pulp was found (p = 0.000) between males and females. The conclusion was that predictions using the pulp volume of the mandibular canine and sex produced the best estimates of chronological age.

An immunohistochemical study of the expression of heat-shock protein-25 and cell proliferation in the dental pulp and enamel organ during odontogenesis in rat molars

OBJECTIVES

The aim of this study is to clarify the functional significance of heat-shock protein (HSP)-25 during tooth development.

DESIGN

We compared the expression of HSP-25 in the dental epithelial and mesenchymal cells with their proliferative activity during odontogenesis in rat molars on postnatal days 1-100 by immunohistochemistry using anti-HSP-25 and anti-5-bromo-2'-deoxyuridine (BrdU) for cell proliferation assay.

RESULTS

On day 1, BrdU-immunoreactive cells were densely located in the inner enamel epithelium in the cervical loop and intercusped areas and the dental pulp adjacent to them, whereas HSP-25-immunoractivity (IR) was restricted to the cusped area where odontoblasts and ameloblasts had already differentiated. Subsequently, BrdU-IR shifted in the apical direction to be localized around Hertwig's epithelial root sheath during days 5-30, never overlapping with concomitantly apically-shifted HSP-25-IR. On days 60-100, BrdU-immunoreactive cells were hardly recognizable in the dental pulp, where HSP-25-IR was exclusively localized in the odontoblast layer. Furthermore, the odontoblast- and ameloblast-lineage cells exhibited two steps in the expression of HSP-25 throughout the postnatal stages: first, dental epithelial and pulpal mesenchymal cells showed a weak IR for HSP-25 after the cessation of their proliferative activity, and subsequently odontoblasts and ameloblasts consistently expressed an intense HSP-25-IR.

CONCLUSION

Odontoblast- and ameloblast-lineage cells acquire HSP-25-IR after they complete their cell division, suggesting that this protein acts as a switch between cell proliferation and differentiation during tooth development. The consistent expression of HSP-25-IR in the formative cells may be involved in the maintenance of their functional integrity.

A light microscopy study of pulps from traumatized permanent incisors with reduced pulpal lumen

The pulps from 20 traumatized permanent maxillary incisors treated endodontically because progressive hard-tissue formation diminished the pulpal lumen, were studied with light microscopy. The tissue changes were characterized by a varied increase in collagen content. A marked increase in collagen content was associated with a marked decrease in number of cells. Areas of mineralized tissue resembling dystrophic mineralization were present in nine pulps. Osteoidlike tissue with included and lining cells was found adjacent to these mineralized areas in three pulps. In one pulp a moderate infiltration of inflammatory cells was noted, mostly lymphocytes. With the exception of the latter tooth, tissue changes in the pulps in no case warranted endodontic treatment.

Histologic analysis of pulpal revascularization of autotransplanted immature teeth after removal of the original pulp tissue

The survival rate of replanted and autotransplanted teeth is mainly affected by the reaction of the pulp. Pulpal necrosis can cause periapical inflammation and inflammatory root resorption. The purpose of this study is to learn more about the pulpal changes in autotransplanted immature teeth whose pulp tissue was removed before transplantation. The experimental material consisted of 16 single-rooted teeth with open apices, from a beagle dog (3 months of age). At day 0, 4 teeth were extracted, the pulpal tissues were removed, and the teeth were then transplanted to their contralateral side. The same procedure was carried out on days 9, 16, and 23, each time for 4 single-rooted teeth. Longitudinal paraffin sections were made for histologic investigation. The results showed that, after 7 days, 2 of the 4 teeth had an ingrowth of new tissue over one fourth of their length. After 14 days, all 4 teeth had ingrowth (> or =one fourth of the pulp chamber). At the 21-day observation, more than half of the pulp chambers of all teeth were filled, and, after 30 days, there was total ingrowth in 3 of the 4 teeth. This new tissue consisted of well-organized and well-vascularized connective tissue.

Immunolocalization of fibroblast growth factor-2 (FGF-2) in the developing root and supporting structures of the murine tooth

Epithelio-mesenchymal interactions are active during the development of the root of the tooth and are regulated by a variety of growth factors, such as fibroblast growth factors. FGF-2, 3, 4, and 8 have all been shown to play a role in the development of the crown of the tooth, but less is known about the factors that govern root formation, particularly FGF-2. The aim of this study was thus to elucidate the spatial and temporal expression of FGF-2 in the root of the developing tooth, as this growth factor is believed to be a mediator of epithelio-mesenchymal interactions. Parasagittal sections of the maxillary and mandibular arches of post-natal mice were utilized and the roots of the molar teeth were studied. Immunocytochemistry utilizing an antibody to FGF-2 was performed on sections of teeth at various stages of development. Intense immunostaining for FGF-2 was observed in differentiating odontoblasts at the apical end of the tooth and in the furcation zone of the developing root at all the stages examined. FGF-2 localization was also observed in cementoblasts on post-natal days 16, 20 and 24. The pattern of localization of FGF-2 in the developing root suggests that this growth factor may participate in the signaling network associated with root development.

Ion Channels Involved in Tooth Pain

The tooth has an unusual sensory system that converts external stimuli predominantly into pain, yet its sensory afferents in teeth demonstrate cytochemical properties of non-nociceptive neurons. This review summarizes the recent knowledge underlying this paradoxical nociception, with a focus on the ion channels involved in tooth pain. The expression of temperature-sensitive ion channels has been extensively investigated because thermal stimulation often evokes tooth pain. However, temperature-sensitive ion channels cannot explain the sudden intense tooth pain evoked by innocuous temperatures or light air puffs, leading to the hydrodynamic theory emphasizing the microfluidic movement within the dentinal tubules for detection by mechanosensitive ion channels. Several mechanosensitive ion channels expressed in dental sensory systems have been suggested as key players in the hydrodynamic theory, and TRPM7, which is abundant in the odontoblasts, and recently discovered PIEZO receptors are promising candidates. Several ligand-gated ion channels and voltage-gated ion channels expressed in dental primary afferent neurons have been discussed in relation to their potential contribution to tooth pain. In addition, in recent years, there has been growing interest in the potential sensory role of odontoblasts; thus, the expression of ion channels in odontoblasts and their potential relation to tooth pain is also reviewed.

Effects of postnatal anti-nerve growth factor serum exposure on development of apical nerves of the rat molar

The present study was undertaken to test the hypothesis that development of the pulpal innervation is dependent on nerve growth factor (NGF). Newborn rats were given subcutaneous injections of a rabbit anti-mouse NGF serum on alternate days for the first 24 days postnatally. Control animals were untreated and normal rabbit serum-treated litter mates. The animals were deeply anesthetized on postnatal day 26, perfused with fixative and the first mandibular molars were processed for transmission electron microscopy to obtain a complete census of axons entering the four roots. The composition of the mental nerve was also examined. Compared to control animals, the apical innervation of molars from anti-NGF-treated rats had only 62% as many myelinated fibers and 41% as many unmyelinated axons. Those myelinated fibers present in antiserum-treated animals were slightly, but significantly, smaller in average diameter than controls. In teeth of control animals, about 20% of all unmyelinated axons were located in fibers coursing outside of nerve fascicles; these isolated fibers were disproportionately rare after antiserum exposure. The average number of unmyelinated axons per Schwann cell unit was also significantly lower. Postnatal exposure to anti-NGF had milder effects on mental nerve composition compared to the tooth innervation. Numbers of myelinated fibers were 83% of controls, unmyelinated axons were 74% of controls and there was no change in the average number of unmyelinated axons per Schwann cell unit. We conclude that development of dental innervation is highly susceptible to postnatal NGF deprivation. This may be a consequence of the mostly nociceptive composition of dental nerves and their late development.

An autoradiographic study of periodontal development in the mouse

Tritiated thymidine was injected into 10- and 13-day-old mice because at this age the third molar is at the appropriate stage of development. At set intervals, the mice were killed and the distribution of labeled cells within the dental papilla and follicle examined. The change in labeling index with time was measured for defined areas in the papilla and follicle. It was shown that, during the late bell stage of development, cells moved from the papilla into the follicle. It was concluded that the pulp, rather than the investing layer of the follicle, is the source of the periodontium and that growth of the pulp and periodontal tissues could generate an important force contributing to tooth eruption.

Dental pulp-derived stem cell conditioned medium to regenerate peripheral nerves in a novel animal model of dysphagia

In nerve regeneration studies, various animal models are used to assess nerve regeneration. However, because of the difficulties in functional nerve assessment, a visceral nerve injury model is yet to be established. The superior laryngeal nerve (SLN) plays an essential role in swallowing. Although a treatment for SLN injury following trauma and surgery is desirable, no such treatment is reported in the literature. We recently reported that stem cells derived from human exfoliated deciduous teeth (SHED) have a therapeutic effect on various tissues via macrophage polarization. Here, we established a novel animal model of SLN injury. Our model was characterized as having weight loss and drinking behavior changes. In addition, the SLN lesion caused a delay in the onset of the swallowing reflex and gain of laryngeal residue in the pharynx. Systemic administration of SHED-conditioned media (SHED-CM) promoted functional recovery of the SLN and significantly promoted axonal regeneration by converting of macrophages to the anti-inflammatory M2 phenotype. In addition, SHED-CM enhanced new blood vessel formation at the injury site. Our data suggest that the administration of SHED-CM may provide therapeutic benefits for SLN injury.

Age estimation in the living: A scoping review of population data for skeletal and dental methods

Age estimation of living individuals has become a crucial part of the forensic practice, especially due to the global increase in cross-border migration. The low rate of birth registration in many countries, hence of identification documents of migrants, especially in Africa and Asia, highlights the importance of reliable methods for age estimation of living individuals. Despite the fact that a number of skeletal and dental methods for age estimation have been developed, their main limitation is that they are based on specific reference samples and there is still no consensus among researchers on whether these methods can be applied to all populations. Though this issue remains still unsolved, population information at a glance could be useful for forensic practitioners dealing with such issues. This study aims at presenting a scoping review and mapping of the current situation concerning population data for skeletal (hand-wrist and clavicle) and dental methods (teeth eruption and third molar formation) for age estimation in the living. Two hundred studies on the rate of skeletal maturation and four hundred thirty-nine on the rate of dental maturation were found, covering the period from 1952 and 2020 for a total of ninety-eight countries. For most of the western and central African countries there are currently no data on the rate of skeletal and dental maturation. The same applies to the countries of the Middle East, as well as the eastern European countries, especially as regard the skeletal development.