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Objective This study examined the expression pattern of the Deleted-in-colorectal-carcinoma (DCC) gene in developing rat tooth germs. Methods Rat pups at 4, 7 and 10 d postpartum were used in this study. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescent localization were used to determine the level of DCC expression during tooth development. Results There was more than 2-fold higher level of DCC mRNA in the rat 2nd maxillary molar tooth germs on 10 d postpartum, which was the root stage, than in the rat 3rd maxillary molar tooth germ, which was at the cap/early bell development stage. In addition, the levels of DCC mRNA in the 2nd maxillary molar germs at 4, 7 and 10 d postpartum increased gradually according to tooth development. Interestingly, immunoreactivity against DCC was specifically detected in the differentiating ameloblasts. DCC was observed in the lateral and apical sides of the newly differentiating and secretory stage ameloblasts. Afterwards, DCC was localized only in the apical side of the maturation stage ameloblasts, not in the lateral side. Conclusion DCC is expressed in the differentiating ameloblasts, which suggests that this molecule plays a crucial role in amelogenesis.

Objective: To test the reliability of some cephalometric measurements in unilateral cleft lip and palate patients. Measurements with A, ANS, and PNS, were compared to measurements performed with alternatives for point A, ANS, and PNS: A1, A2, ANS1, ANS2, and PNS1. Patients: One hundred sixty-four children with complete unilateral cleft lip and palate (UCLP), with a lateral head film taken at age 4 to 6 years. Mean Outcome Measures: Intraobserver and interobserver reliability for cephalometric measurements including A, ANS, PNS or their alternatives: Dahlberg errors, systematic errors, and Pearson correlation coefficients were calculated. Results: The measurements using ANS and PNS or their alternatives, were comparable. The systematic error between observers for measurements using A2 was less than for measurements using A or A1. The scatterplot of point A showed a slightly better distribution of the points than the plots of A1 and A2. Conclusions: Although the landmarks A, ANS, and PNS are hard to trace in UCLP patients with tooth germs in the anterior maxilla, no better landmarks were found in this study. Cephalometric studies using A, ANS, and PNS in UCLP patients should be interpreted with caution.

The maxillofacial skeleton is different from the bones elsewhere in the body in several aspects. Embryologically, it is unique as parts of it develop from cells migrating from the embryonal neuroectoderm. Furthermore, they house the tooth germs. Due to these special features, diseases occur in this area that are not seen in any other part of the skeleton. Moreover, bone diseases with a more generalized distribution are connected with entirely different differential diagnostic problems when located in the maxillofacial area because of specific clinical, radiological, and histological details at this site. To put these issues in the right perspective, both bone disorders that are restricted to the head and neck and diseases that also occur in the extragnathic skeleton are discussed in this chapter.

Innervation plays a key role in the development, homeostasis and regeneration of organs and tissues. However, the mechanisms underlying these phenomena are not well understood yet. In particular, the role of innervation in tooth development and regeneration is neglected. Several in vivo studies have provided important information about the patterns of innervation of dental tissues during development and repair processes of various animal models. However, most of these approaches are not optimal to highlight the molecular basis of the interactions between nerve fibres and target organs and tissues. Co-cultures constitute a valuable method to investigate and manipulate the interactions between nerve fibres and teeth in a controlled and isolated environment. In the last decades, conventional co-cultures using the same culture medium have been performed for very short periods (e.g., two days) to investigate the attractive or repulsive effects of developing oral and dental tissues on sensory nerve fibres. However, extension of the culture period is required to investigate the effects of innervation on tooth morphogenesis and cytodifferentiation. Microfluidics systems allow co-cultures of neurons and different cell types in their appropriate culture media. We have recently demonstrated that trigeminal ganglia (TG) and teeth are able to survive for a long period of time when co-cultured in microfluidic devices, and that they maintain in these conditions the same innervation pattern that they show in vivo. On this basis, we describe how to isolate and co-culture developing trigeminal ganglia and tooth germs in a microfluidic co-culture system.This protocol describes a simple and flexible way to co-culture ganglia/nerves and target tissues and to study the roles of specific molecules on such interactions in a controlled and isolated environment.

Forensic research requires the application of reliable identification methods for unidentified individuals, among which the dental analysis has prime importance. The most significant source of dental evidence is oral autopsy applications, which consist of an examination and evidence collection from the oral cavity of a deceased individual. Oral autopsies show variations depending on the age of the person due to rigor mortis. The oral autopsy of a child may require an easier operation than adults, and thus, the procedures are usually simpler for fetus or infant cases. The aim of this study is to propose the theoretical and experimental aspects of an oral autopsy protocol for a special age group of fetus or infant cases, which is a method for extracting tooth germs in their developmental stages for identification purposes and entitled by the authors’ names as the “Aka-Canturk Oral Autopsy Method”.

Tooth replacement poses many questions about development, pattern formation, tooth attachment mechanisms, functional morphology and the evolution of vertebrate dentitions. Although most vertebrate species have polyphyodont dentitions, detailed knowledge of tooth structure and replacement is poor for most groups, particularly actinopterygians. We examined the oral dentition of the bluefish, Pomatomus saltatrix, a pelagic and coastal marine predator, using a sample of 50 individuals. The oral teeth are located on the dentary and premaxillary bones, and we scored each tooth locus in the dentary and premaxillary bones using a four-part functional classification: absent (A), incoming (I), functional (F=fully ankylosed) or eroding (E). The homodont oral teeth of Pomatomus are sharp, deeply socketed and firmly ankylosed to the bone of attachment. Replacement is intraosseus and occurs in alternate tooth loci with long waves of replacement passing from rear to front. The much higher percentage of functional as opposed to eroding teeth suggests that replacement rates are low but that individual teeth are quickly lost once erosion begins. Tooth number increases ontogenetically, ranging from 15-31 dentary teeth and 15-39 premaxillary teeth in the sample studied. Teeth increase in size with every replacement cycle. Remodeling of the attachment bone occurs continuously to accommodate growth. New tooth germs originate from a discontinuous dental lamina and migrate from the lingual (dentary) or labial (premaxillary) epithelium through pores in the bone of attachment into the resorption spaces beneath the existing teeth. Pomatomus shares unique aspects of tooth replacement with barracudas and other scombroids and this supports the interpretation that Pomatomus is more closely related to scombroids than to carangoids.

We examined whether tooth eruption would occur normally in grafted allogeneic mandibular bone.Using vascularized composite tissue transplantation, we extracted portions of immature mandibles including the tooth germs from young beagle dogs and transplanted them into unrelated immature or mature beagle dogs. In addition, we prepared vascularized gingival flaps from mature dogs and grafted them onto the mandibles of unrelated immature dogs. Mandibular bone including tooth germs without covering gingiva from immature dogs was also transplanted either to immature or mature recipient dogs, and the grafted bones were covered with recipients' gingiva. Then, we examined tooth eruption in these grafted mandibular bones.Normal tooth eruption was observed only in the mandibles transplanted to the young recipient dogs. In the mature dogs, tooth eruption from the gingiva was delayed; the whole crown was covered with a cap of gingival tissue, which was not a gingival overgrowth.It is suggested that tooth eruption depends on the age of the recipient, regardless of the overlying gingival tissues transplanted.

This study presents the treatment courses in three impacted cases of mandibular second premolars caused by distal inclination of the tooth germs. In all cases, the second premolars were surgically exposed, but the traction periods until oral emergence differed. The reasons for the differences may be the variation in the severity of the distal inclinations of the tooth germs and the calcified development of the affected germs at fenestration.

Fusion is the union of two normally adjacent tooth germs resulting in the formation of a single large tooth. The incidence of fused teeth is 0.1% in the permanent and 0.5% in the primary dentitions and it may be unilateral or bilateral. The purpose of this article is to report a rare case of unilateral fusion of permanent mandibular lateral incisor and canine with two pulp chambers and a single root canal.

Juveniles of the Mekong giant catfish, Pangasianodon gigas (Teleostei), have 3 sorts of tooth-upper and lower jaw teeth, palatal teeth, and pharyngeal teeth--but adults are toothless. To investigate the histogenesis and disappearance of the teeth, we made serial sections of the mouth and teeth of juvenile fish at 10 developmental stages (from ca. 8.5 to ca. 30 cm in total length) and examined them under scanning electron microscope and light microscope. Observations of teeth and surrounding tissues in the serial sections revealed the process of tooth resorption by active odontoclast-like cells. Numbers of jaw and palatal teeth decreased with age. When the fish reached ca. 14 cm in total length, the numbers of functional upper jaw teeth and successional tooth germs decreased rapidly, and the developmental rate of successional tooth germs slowed. When the fish reached ca. 24 cm, no teeth existed in the upper jaw. It is clear that tooth disappearance results from the shedding of functional teeth and the lack of replacement tooth germs.

The tooth is an ectodermal organ that arises from a tooth germ under the regulation of reciprocal epithelial-mesenchymal interactions. Tooth morphogenesis occurs in the tooth-forming field as a result of reaction-diffusion waves of specific gene expression patterns. Here, we developed a novel mechanical ligation method for splitting tooth germs to artificially regulate the molecules that control tooth morphology. The split tooth germs successfully developed into multiple correct teeth through the re-regionalisation of the tooth-forming field, which is regulated by reaction-diffusion waves in response to mechanical force. Furthermore, split teeth erupted into the oral cavity and restored physiological tooth function, including mastication, periodontal ligament function and responsiveness to noxious stimuli. Thus, this study presents a novel tooth regenerative technology based on split tooth germs and the re-regionalisation of the tooth-forming field by artificial mechanical force.

Fusion of the teeth is a developmental anomaly that may occur due to joining of the two separated tooth germs. It may be complete or incomplete based on which stage of development the fusion occurred. Physical forces or pressure may cause fusion. It can be seen between the two primary teeth or permanent teeth or between normal and supernumerary teeth, commonly mesiodens.1 In this case, an …

Supernumerary teeth need to be removed because they can cause various complications. Caution is needed because their removal can cause damage to permanent teeth or tooth germs in the local vicinity. Surgical guides have recently been used in maxillofacial surgery. Because surgical guides are designed through preoperative analysis by computer-aided design software and fabricated using a 3-dimensional printer applying computer-aided manufacturing technology, they increase the accuracy and predictability of surgery. This report describes 2 cases of removal of a mesiodens-1 from a child and 1 from an adolescent-using a surgical guide; these would have been difficult to remove with conventional surgical methods.

This paper builds a morphometric framework for the analysis of dental pulp fibroblast evolution during tooth development. We investigated 15 tooth germs (cases) organized, by histological criteria, in three groups corresponding to cap, early bell, and late bell stages, respectively. Each group comprised five cases. The morphometric description used the following parameters: areaA, perimeterP—automatically extracted by a color segmentation technique, and form factor (FF)—calculated as4πA/P2. The designed framework operated at inter- and intragroup levels. The intergroup analysis quantified the differences between groups, in the sense of a relative distance (RD) adequately defined by mean-value scaling. We showed that the stage of early bell is approximately 5 times closer to late bell than to cap. The quantification procedure required concomitant information aboutA,Pparameters (asP versus Adependences, orFFvalues), whereas the procedure failed forAorPseparately used. The intragroup analysis quantified the similarity of the cases belonging to the same stage. We proved that, unlike the intergroup tests, the individual exploitation of all three descriptorsA,P, andFFis effective, yielding highly compatible results. Within any group, most cases presented RDs less than 10% from the group mean value, regardless of the descriptor type.

Missing teeth are one of the most common developmental problems in children. The adult teeth are more frequently affected than the baby teeth. Fusion defined as the merger of two adjacent tooth germs producing one tooth. These teeth may be fused by enamel, dentin, or both. The fused crown is broader than non fused adjacent teeth and thus resembles gemination. However, tooth counting reveals decreased numbers. Fused teeth are rare in the permanent dentition. A case of simultaneous missing upper incisors and fused lower incisors is reported.

In order to elucidate the role of parathyroid hormone-related peptide (PTHrP) in tooth development, we treated tooth germ explants of mouse molars with antisense phosphorothioate-oligodeoxynucleotide (ODN) against PTHrP. Antisense ODN-treatment of the explants resulted in the invasion of the tooth germs by bone. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells around the tooth germs in antisense ODN-treated explants was much lower than that of the control explants. Electron microscopic examination suggested that the antisense ODN-treatment inhibited differentiation of osteoclasts. Treatment of the explants with bisphosphonate or vitamin K2, inhibitors of the differentiation of osteoclasts, induced the invasion by bone into the tooth germs as observed in the antisense ODN-treated explants. The results obtained suggest that PTHrP is involved in the mechanism protecting tooth germs from bone invasion by promoting the differentiation of osteoclasts around them.

Four clinical cases are presented to demonstrate the self-correcting potential of aberrant tooth germs after the elimination of eruption obstacles (in 2 cases cysts, in 2 other cases severely infraoccluded primary teeth). In the case of the submerging deciduous teeth, the tilted adjacent teeth were orthodontically uprighted after the surgical procedure. Possible causative mechanisms are discussed.

Microcomputerized tomography (micro‐CT) allows discriminating very small changes in dental hard tissue volumes. The aim of the present study was to create a new method for obtaining high‐resolution, three‐dimensional images of dental hard tissue development using micro‐CT, and to observe the changes in dental hard tissue development and composition in growing rat pups. Tooth germs from rats at the end of the 20‐day embryonic period (E20) and during the neonatal period (D1‐14) were subjected to micro‐CT. Three‐dimensional reconstructions were analyzed to compare dental hard tissue formation and mineralization during the different development periods. Scanning electron microscopy and energy dispersive spectroscopy were used to confirm mineral density (MD). Dental hard tissue began to form during the E20, but the process was slow and resulted in minimal deposition. Hard tissue volume increased by approximately 0.040 mm3/day from E20 to D3, and by 0.12‐0.42 mm3/day after D3, peaking at 0.42 mm3/day at D12. This increase in hard tissue volume resulted in continuous increases in hard tissue thickness, from 90.0 ± 20.7 μm at E20 to 545.2 ± 14.1 μm by D14. MD was 298 ± 3.1 mg HA/cm at E20 and increased to 678.2 ± 6.1 mg HA/cm by D14. The degree of calcification also progressively increased during the first 14 days of development. Dental MD was strongly associated with calcification. This study indicates that micro‐CT is a nondestructive, high‐resolution, reliable, and innovative tool for the evaluation of volume and MD of dental hard tissues during development. Micro‐CT minimizes artifacts caused by sample preparation. PACS number: 87

Fusion Tooth due to the union of two separated tooth germs, it may be complete or incomplete tooth fusion depending on the time of union and stages of tooth development. It may be between two normal teeth or sometimes between normal tooth and supernumerary tooth germ. Here we report a rare case of fusion between right mandibular primary central and lateral incisors in a six year old girl.

永久歯歯式が5134/4134=50とされている有袋類のハイイロジネズミオポッサム (Monodelphis domes-tica) を用いて, 歯堤と歯胚の発生様式および細管エナメル質の構造とエナメル細管の機能について, 組織学的検索を行った. 12, 16, 18日齢の観察から, 上・下顎の乳犬歯・第3乳臼歯・第1大臼歯および上顎の第1乳切歯・第2大臼歯の歯胚に, 代生歯堤ないし代生歯胚が確認された. 上顎第4切歯部と下顎第1切歯部では, 乳歯の歯胚が退縮するのが認められた. 歯堤は上顎第1乳切歯部を除き, 上・下顎でそれぞれすべて連続し, 下顎第3大臼歯部以外の各歯胚の近心あるいは遠心の部位で口腔上皮と連絡していた. すなわち, 上顎第1乳切歯, 上・下顎の乳犬歯・第1大臼歯は, 第一生歯 (乳歯) が永久歯化し, 上顎第4切歯および下顎第1切歯は, 第二生歯 (代生歯) が永久歯化したと推測される. 上・下顎の第3乳臼歯のみは, 第二生歯 (第3小臼歯) に交換することが確認された. エナメル結節, エナメル索, 中間層というエナメル器の組織分化は, 真獣類と同様に観察された. エナメル小柱は, エナメル象牙境から斜めに派生し, 咬頭頂へ向かうが, エナメル質表面近くになると急に屈曲し, 周囲を小柱間エナメル質に囲まれていた. エナメル細管は, エナメル象牙境付近では, エナメル小柱・小柱間エナメル質に分布し, 1本のエナメル小柱内に複数の細管が存在することもあった. エナメル質中層から表層では, エナメル細管は各エナメル小柱内に1本ずつ分布し, エナメル象牙境からエナメル質表面近くまで連続した1本のエナメル細管が確認されたが, 小柱間エナメル質には認められなかった. エナメル細管が1個のエナメル芽細胞と深く係りあって形成されたものと推定できる. エナメル細管内に, 象牙芽細胞の突起である象牙線維が象牙細管から連続して, 分枝して分布しているのが認められた. これは, 象牙芽細胞の突起もエナメル細管の形成に関与することを示すと考えられる. 塩化ストロンチウムおよびテトラサイクリンの生体投与実験を行った結果, 両者がエナメル細管およびエナメル質の表面近くまで達しているのが検出された. これは, 象牙芽細胞の関与による, エナメル細管を介した物質の輸送機能があることを示している.

Introduction Regenerating a tooth completely in human oral cavity is not achieved by current studies yet. Here, we have conceived a man-induced method to construct a teeth germ which might be used to regenerate a tooth in vivo. This idea was generated by traits of the development of the compound odontoma, a benign tumour of tooth malformation. This is a kind of developmental tooth malformation, characterised by several small teeth inside the entity. Those scattered denticles/daughter teeth germs, formed in the early stage of odontoma morphogenesis, show similar layers as in a normal tooth, and could grow into tooth-like shapes. In consideration with recent report that mouse tooth germ constructed in vitro could develop into a fully functioned tooth in adult mouse jaws. We hope this hypothesis helps generate tooth germs for in vivo implantation. Hypothesis Tooth germ of wisdom tooth might be separated into small daughter germs by bone trabecular using tissue-engineering method, to provide more than one tooth germ for tooth regeneration. Evaluation of hypothesis By reconstruction existing dental tissues during tooth organgenesis in the jaw, this hypothesis shows advantage than generating tooth from single stem cell or artificial tooth graft. Conclusion Proving this hypothesis not only facilitates the acquirement of numerous homologous and immunological rejection-free teeth germs to treat tooth loss and deficit, but also helps afford an alternative lesson that merits attention in other human organ regeneration fields.

Explant culture allows manipulation of developing organs at specific time points and is therefore an important method for the developmental biologist. For many organs it is difficult to access developing tissue to allow monitoring during ex vivo culture. The slice culture method allows access to tissue so that morphogenetic movements can be followed and specific cell populations can be targeted for manipulation or lineage tracing. In this paper we describe a method of slice culture that has been very successful for culture of tooth germs in a range of species. The method provides excellent access to the tooth germs, which develop at a similar rate to that observed in vivo, surrounded by the other jaw tissues. This allows tissue interactions between the tooth and surrounding tissue to be monitored. Although this paper concentrates on tooth germs, the same protocol can be applied to follow development of a number of other organs, such as salivary glands, Meckel's cartilage, nasal glands, tongue, and ear.

‘As rare as hens’ teeth’ is a well-known expression, implying something is so rare that it doesn’t exist: modern-day hens, like all birds, do not have teeth, although their early fossil ancestors did. Teeth develop through complex interactions between the lining of the mouth (epithelium) and the underlying layer (mesenchyme). Although chick epithelium may lack some of the normal signalling factors, experimental manipulation has produced tooth germs in developing chick embryos. In one mutant chick (talpid2), tooth germs are present without manipulation.

Introduction The major challenge in dental pulp engineering is to make a successful combination of stem cells and biomaterials with the aim of providing the differentiation of stem cells into odontogenic cell types. Among biomaterials, some types of pluronics have been reported to increase bone formation of stem cells. The effect of these pluronics on odontogenic differentiation has not been addressed yet. This study aimed to examine the effect of pluronics F68, F127, and P85 on odontogenic differentiation of stem cells derived from third molar tooth germs of young adults. Methods Human tooth germ stem cells (hTGSCs) were induced to differentiate into odontogenic cells in the presence of different concentrations of pluronics. Differentiation efficiency was assessed by quantitative real-time polymerase chain reaction for determining expression messenger RNA levels and by immunocytostaining for determining the protein expression of odontogenic markers (ie, dentin sialoprotein, dentin matrix protein 1, bone morphogenic protein 2, bone morphogenic protein 7) by measuring alkaline phosphatase enzyme activity and lastly by von Kossa staining for determining mineralization. Results The results revealed for the first time that F68 has a great potential to boost odontogenic differentiation of hTGSCs. P85 was found to reduce cell viability during differentiation. F127 was nontoxic to hTGSCs but did not have any effect on differentiation. Conclusions The positive effect of F68 on odontogenic differentiation might enable more efficient pulp regeneration. Yet, the exact mechanism of how F68 alters the differentiation pattern of hTGSCs remains to be investigated in the future studies. © 2013 American Association of Endodontists.

The pharyngeal dental formula ofMylopharyngodon piceus is 4–5 as a rule, and the dentition is asymmetrical. It is difficult to identify each tooth in the larval dentition. In this paper the appearance pattern of tooth germ with development process in this fish is described in detail. The formation pattern of the left dentition is contrasted with that of the right one. In the developmental process, the left pharyngeal dentition lacks teeth at position An3. Thus the left dentition is D-type as designated by Nakajima (1984), while the right one is A-type.

Recently, sonography of the fetal face has gained increasing importance in prenatal diagnosis. It is not yet clear whether sonographic depiction of fetal tooth germs would have an influence on the prenatal diagnosis of ectodermal dysplasia syndromes. During routine malformation screening, horizontal sections of fetal jaws were visualized and examined for tooth germs in 124 pregnant women following sonographic 'facing'. Histological jaw sections of fetuses that had died in utero at various gestational ages were produced in order to examine the degree of correspondence between the sonographic and histological findings. At least four tooth germs were found in the jaws of all fetuses between 19 and 34 gestational weeks (n = 104). Although jaw visualization was possible between 14 and 18 gestational weeks (n = 20), the exact number and location of the tooth germs could not be determined. Assessment of tooth germs may become increasingly important, as aplasia of the tooth germs is one of the principal signs of various hereditary ectodermal diseases.

Crown dilaceration of permanent teeth occurs due to the non-axial displacement of the already formed hard tissue portion of the developing crown at an angle to their longitudinal axis due to trauma to the primary predecessors. This is a rare condition, representing only 3% of the total of injuries to developing teeth and usually occurs in permanent maxillary incisors because of the close proximity of their tooth germs to the primary incisors, which are more susceptible to trauma. This alteration frequently results from the intrusion of a primary tooth when the child is around 2 years of age, at which time half of the crown of the permanent successor is already formed. Teeth with dilacerated crowns may either erupt with buccal or lingual displacement or remain impacted. The treatment may involve endodontic, orthodontic, restorative and prosthetic procedures. This paper reports the restorative treatment proposed to reestablish the esthetics and function of the affected teeth in three cases of crown dilaceration in permanent maxillary incisors after trauma to their primary predecessors.

The use of deoxyoligonucleotide microarrays facilitates rapid expression profiling of gene expression using samples of about 1 μg of total RNA. Here are described practical aspects of the procedures involved, including essential reagents. Analysis of results is discussed from a practical, experimental, point of view together with software required to carry out the required statistical analysis to isolate populations of differentially expressed genes.

急速凍結置換, 乾式乳剤貼付法を用いて, ラット切歯のエナメル質形成野, および成熟野における32P-リン酸の動態をChemography発生に留意しつつ検索した。16日齢ラットにエーテル麻酔下でH3 [32P] O4の水溶液を注入し一定時間後に断頭, 切片を無水的に作製した。切片上をコロジオン膜で被覆してから乾式法で乳剤を貼付し露出後, 現像, 検鏡した。軟組織上および硬組織上での銀粒子数の計測ならびに統計処理を行い, 銀粒子の分布の経時的変化を調べた。その結果形成期では, 32Pはエナメル器の細胞層を急速に通過してエナメル質に達し全層にわたって急速に拡散する一方で, 表層から深層へのゆっくりとした移動様式も存在することが明らかとなった。また成熟期では, 32Pはエナメル器の細胞の制御をうけずにエナメル質に急速に達し, エナメル質への32Pの添加量とその経時的変動は成熟期エナメル芽細胞の形態変化に密接に関連することが明らかとなった。

Background Dental pulp stem/stromal cells (DPSCs) are categorized as adult stem cells (ASCs) that retain multipotent differentiation capabilities. DPSCs can be isolated from individuals at any age and are considered to be true personal stem cells, making DPSCs one of the potential options for stem cell therapy. However, the properties of DPSCs from individuals with an inherited genetic disorder, such as Huntington's disease (HD), have not been fully investigated. Results To examine if mutant huntingtin (htt) protein impacts DPSC properties, we have established DPSCs from tooth germ of transgenic monkeys that expressed both mutant htt and green fluorescent protein (GFP) genes (rHD/G-DPSCs), and from a monkey that expressed only the GFP gene (rG-DPSCs), which served as a control. Although mutant htt and oligomeric htt aggregates were overtly present in rHD/G-DPSCs, all rHD/G-DPSCs and rG-DPSCs shared similar characteristics, including self-renewal, multipotent differentiation capabilities, expression of stemness and differentiation markers, and cell surface antigen profile. Conclusions Our results suggest that DPSCs from Huntington monkeys retain ASC properties. Thus DPSCs derived from individuals with genetic disorders such as HD could be a potential source of personal stem cells for therapeutic purposes.

Congenital absence of tooth germs and presence of supernumerary teeth (CHH) are anomalies which are classified as embryologically determined disorders. Both disorders can occur together (CHH), but relatively rarely.The aim of the present study was to present and analyze nine cases collected during the past 24 years, where congenitally missing teeth occurred with supernumerary teeth in the same patient.Dental records, radiographs and casts of nine patients, six boys and three girls (aged 9-29 years, mean age: 19 years) were examined. All the family members of the patients were also investigated regarding the presence of tooth disorders.The boys showed hypo-hyperodontia twice as often as the girls (6:3). Congenital absence of tooth germs was more common than the presence of supernumerary teeth (25:11). CAP were not present in the other family members.The full diagnosis of hypo-hyperodontia is only possible on the basis of radiographic examination, because some teeth may remain unerupted or missing. The results of this study showed that concomitant hypo-hyperodontia is rare and sex-related, with predominance of hypodontia. The genetic influence seems unclear.

Objective This study was undertaken to describe 2 cases of localized Langerhans cell histiocytosis (LLCH) of the mandible that healed quickly following intralesional infiltration of corticosteroids. Study Design Two patients with LLCH of the mandible were treated in a 1-stage procedure with intralesional injection of methylprednisolone. Symptoms of pain were quickly relieved and the swelling receded. Periodic orthopantomogram and computerized tomography after corticosteroid injection revealed continuous regression of mandibular osteolysis and a favorable osseous consolidation in the lesions. Conclusions The results of this report suggest that intralesional injection of corticosteroids should be the initial choice of treatment of LLCH of the mandible, especially in children to preserve tooth germs.

Odontogenic tumours are considered to be relatively rare; however, several histologically distinct types have been identified in dogs. The more common canine odontogenic tumours are peripheral odontogenic fibroma and canine acanthomatous ameloblastoma. The expression of cytokeratins (CKs) has been established for the human dental germ and odontogenic tumours. The aim of the present study was to describe the immunohistochemical expression of a panel of CKs in the epithelium of the canine dental germ, normal gingiva and odontogenic tumours arising in this species. Samples from 20 odontogenic tumours, 12 tooth germs and three normal gingival tissues were obtained. Each sample was stained with haematoxylin and eosin and subjected to immunohistochemistry for CK expression. The typical expression pattern of CKs in the odontogenic epithelium and gingiva of dogs was CK14 and CK5/6. CKs 7, 8, 18 and 20 were generally absent from the canine dental germ, gingiva and odontogenic tumours. Dogs and man therefore exhibit similar CK expression in the odontogenic epithelium.

The purpose of this article is to report the orthodontic treatment of a patient with extremely delayed development of the maxillary lateral incisors. At 7 years of age, the boy's permanent maxillary lateral incisors had not erupted. A radiograph showed no tooth germs in place, although well-defined radiolucent areas were evident. Removal of the radiolucent areas was contemplated, but it was rejected in favor of a conservative approach. At age 13, peg-shaped maxillary lateral incisors erupted; they were positioned during orthodontic treatment and reshaped with composite restorations, providing good esthetics and function.

The aim of this study was to determine the presence of third molar germs in patients with Class II/2 and Class III malocclusions. The study comprised 146 examinees from Zagreb and Istria. Examinees with Class II/2 malocclusions amounted to 77 and those with Class III 69. With regard to development of dentition the examinees were divided into two groups: Group I subjects with early mixed dentition (23 subjects with Class II/2 and 21 subjects with Class III), and Group II subjects with late mixed dentition (54 subjects with Class II/2 and 48 subjects with Class III). Assessments were made from panoramic radiographs and lateral cephalograms. The Pearson chi2-test and Fisher's exact test was used to determine statistical significance in differences. Assessments showed that third molar germs were present significantly more often in the upper jaw in Class II/2 (58% vs. 44%) and in the lower jaw in Class III (83% vs. 69%). In subjects with Class II/2 all third molar germs were present statistically more often in late mixed dentition, which was also determined for maxillary third molar germs in Class III. The presence of mandibular third molar germs in Class III examinees was almost equal in both periods of mixed dentitions. The study confirmed correlation between the presence of third molar germs and sagital maxillomandibular relationship and encourages investigation of the differences in calcifications of all permanent teeth in such malocclusions.

Using an immunohistochemical assay 10 benign odontogenic tumors were evaluated for expression of the HRAS- and KRAS-encoded gene products p21RAS. Overexpression of p21RAS was found in ameloblastomas, ameloblastic fibromas and odontogenic myxomas compared with normal human developing teeth. The highest expression was noted in a recurrent plexiform ameloblastoma in which almost 100% of the tumor cells were brightly reactive. In general, p21RAS was preferentially expressed in ectodermal cells of odontogenic tumors, consistent with the findings in the tooth germs. The significance of p21RAS expression is considered in relation to the biological behavior of ameloblastomas.

Porcine tooth germ was investigated immunochemically and immunocytochemically using antibodies against a synthetic N-terminal peptide fragment from a 32 kDa nonamelogenin found in the inner (old) secretory enamel. In immunochemical preparations, these antibodies reacted to many proteins of differing molecular weights, especially to 140 kDa, 89 kDa, 56 kDa, 45 kDa, and 32 kDa proteins. Analysis of the layers of enamel suggested that the 140 kDa and/or 89 kDa proteins, both of which were found in newly formed enamel, were the parental proteins secreted by the ameloblasts, and that they were degraded to produce 32 kDa and other low molecular-weight proteins associated with progressive mineralization. In immunohistochemical preparation, immunoreactivity at the differentiation stage was detected initially over the amorphous dense material or fine fibrils around calcified globules in predentin, while the stippled material was devoid of immunoreactivity. The amorphous dense material seemed to give rise to a continuous layer of initial enamel. At the matrix formation stage, the immunoreactivity of immature enamel just beneath the putative secretory face of the Tomes' processes was intense. From the surface of the enamel matrix to a depth of about 100 microns, immunoreactivity of prism sheaths was weaker than that of enamel prisms, producing a reverse honeycomb pattern. In the enamel matrix deeper than 100 microns, immunoreactivity was weak and homogeneously distributed. The Golgi apparatus and secretory granules of the secretory ameloblasts showed immunoreactivity. These results suggest that the likely parent proteins of the 32 kDa nonamelogenin protein, i.e., the 140 kDa and/or 89 kDa proteins, play a significant role in the calcification of the enamel matrix.

Complementary to the micro-PIXE experiments performed on hamster tooth germs to elucidate the role of fluoride during the growth, the photon microprobe at Daresbury was used to obtain information on the distribution of Zn. The germs of fluoride-administered hamsters, together with a control group, were analyzed with the micro-synchrotron radiation fluorescence method (micro-SXRF).

Enamel proteins from fully mineralized human molars and from bovine tooth germs were separated by electrophoresis. The gels were stained for detection of glycoproteins, lipoproteins, and phosphoproteins. Glycoproteins were shown by periodic acid-Schiff staining and lectin blotting. In mature human enamel a number of high molecular weight proteins could be demonstrated after ethylenediaminetetra-acetic acid demineralization and subsequent Triton X-100 extraction. These proteins are suggested to be lipoproteins. Phosphoproteins could only be visualized in enamel matrix from the tooth germs.

In this paper we elucidate the pattern of initiation of the first teeth and the pattern of tooth replacement on the dentary of wild Atlantic salmon (Salmo salar L.), throughout nearly all stages of its life cycle, using serially sectioned heads and jaws, cleared and stained animals, and X-rays. The dentary teeth are set in one row. Tooth germs appear around hatching, first in odd positions, followed by even positions. From position 8 further backwards, teeth are added in adjacent positions. The first replacement teeth appear in animals of about 30 mm fork length. On the dentary of early life stages (alevins and fry), every position in the tooth row holds a functional (i.e. attached and erupted) tooth and a replacement tooth. The alternating pattern set up anteriorly in the dentary by the first-generation teeth changes in juveniles (parr) whereby teeth are in a similar functional (for the erupted teeth) or developmental stage (for the replacement teeth) every three positions. This pattern is also observed in marine animals during their marine life phase and in both sexes of adult animals prior to spawning (grilse and salmon), but every position now holds either a functional tooth or a mineralised replacement tooth. This is likely due to the fact that replacement tooth germs have to grow to a larger size before mineralisation starts. In the following spring, the dentary tooth pattern of animals that have survived spawning (kelts) is highly variable. The abundance of functional teeth in post-spawning animals nevertheless indicates that teeth are not lost over winter. We confirm the earlier reported lack of evidence for the existence of an edentulous life phase, preceding the appearance of so-called breeding teeth during upstream migration to the spawning grounds, and consider breeding teeth to be just another tooth generation in a regularly replacing dentition. This study shows how Atlantic salmon maintains a functional adaptive dentition throughout its complex life cycle.

Dioxins are ubiquitous environmental poisons that cause disturbances in developing organs, including the teeth. Exposure to 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) at the cap stage leads to reduced tooth size and deformation of cuspal morphology. Our hypothesis was that TCDD affects the expression of genes specific for tooth development, which leads to these aberrations. Mouse embryonic E14 tooth germs were cultured for 24 hrs with/without 1 μM TCDD. Analysis of total RNA on Affymetrix arrays showed that TCDD altered the expression of 31 known genes by a fold factor of at least 2. Genes implied in tooth development expressed only slight changes. Genes active at the cap stage were selected for quantitative PCR analysis. Of these, the most highly up-regulated were Follistatin and Runx2, while TGFβ 1 and p21 were the most down-regulated genes. Incomplete tooth morphogenesis caused by TCDD may thus result from modified expression of developmentally regulated genes.

The replacement of teeth by implants is usually restricted to patients with completed craniofacial growth. Implant insertions in children or adolescents are circumvented due to several unfavorable potential effects including trauma to tooth germs, tooth eruption disorders and multidimensional restrictions of skeletal craniofacial growth. Moreover, the functional and esthetic results of the oral rehabilitation are only temporary acceptable. However, to a small number of pediatric patients suffering congenitally from severe hypodontia caused by syndromes such as ectodermal dysplasia, conventional prosthodontic rehabilitations are insufficient. We report the case of a boy with ectodermal dysplasia who exhibited a severe hypodontia and who was treated with implants inserted into the anterior mandible at the age of 8 years. The implants were functionally loaded and resulted in a high patient satisfaction. We recommend the early insertion of dental implants in children with severe hypodontia. Reviewing the current literature, several aspects of syndromic hypodontia, patient selection and implant planning are discussed.

The Eretmodini are closely related cichlids endemic to Lake Tanganyika with very divergent oral tooth shapes, ranging from spatulate in Eretmodus to conical in Tanganicodus. To study how closely related cichlids can generate such divergent tooth shapes, we investigated how the enamel organ directs the develop- ment of spatulate teeth in Eretmodus cf. cyanostictus (lin- eage A), both in ontogeny and in adults, and of conical teeth in adult Tanganicodus cf. irsacae, using 3D- reconstructions from serially sectioned tooth germs. The spatulate oral tooth shape that characterizes adult E. cf. cyanostictus (lineage A) is preceded early in ontogeny by a conical tooth shape. We propose two possible hypotheses to account for changes in the folding of the enamel organ (in particular its epithelio-mesenchymal boundary) capa- ble of generating such distinct tooth shapes. Different arguments lead us to favor the hypothesis of an asymmet- ric growth and differentiation of the enamel organ, such that the tip of a conical tooth corresponds to one "corner" of a spatulate tooth. Applying current molecular models of tooth shape variation, this would imply the existence of asymmetric fields of inhibition. Whether such asymmetric growth reflects the reutilization of a simple mechanism operating in ontogeny has to be clarified. J. Morphol. 267: 516 -525, 2006. © 2006 Wiley-Liss, Inc.

Rodent incisors are known to be continuously growing teeth that are maintained by both the cell-proliferation at the apical end and the attrition of the incisal edge. This type of tooth had a special epithelial structure for the maintenance of stem cells, showing the bulbous epithelial protrusion at the apical end. The morphological transition of the epithelial-mesenchymal compartment by serial transverse sections of the apical end toward the incisal direction is likely to reflect the development of the tooth germ in the prenatal stage. Based on the present histological and previous molecular biological studies, the special structure at the apical end is obviously different from the cervical loop giving rise to Hertwig's epithelial root sheath (HERS), in human, mouse and rat molar tooth germs. Hence, we propose a new concept that the eternal tooth bud producing various dental progeny is formed at the apical end of continuously growing teeth, and a new term "apical bud" for indicating this specialized epithelial structure. Furthermore, BrdU labelling analysis suggested that the guinea-pig molars, which were continuously growing teeth, also possessed plural specific proliferative regions and "apical bud" at the apical end.

The functions of p107 and p130, members of the retinoblastoma family,include the control of cell cycle progression and differentiation in several tissues. Our previous studies suggested a role for p107 and p130 in keratinocyte differentiation in vitro. We now extend these data using knockout animal models. We found impaired terminal differentiation in the interfollicular keratinocytes of p107/p130-double-null mice epidermis. In addition, we observed a decreased number of hair follicles and a clear developmental delay in hair, whiskers and tooth germs. Skin grafts of p107/p130-deficient epidermis onto NOD/scid mice showed altered differentiation and hyperproliferation of the interfollicular keratinocytes,thus demonstrating that the absence of p107 and p130 results in the deficient control of differentiation in keratinocytes in a cell-autonomous manner. Besides normal hair formation, follicular cysts, misoriented and dysplastic follicles, together with aberrant hair cycling, were also observed in the p107/p130 skin transplants. Finally, the hair abnormalities in p107/p130-null skin were associated with altered Bmp4-dependent signaling including decreasedΔNp63 expression. These results indicate an essential role for p107 and p130 in the epithelial-mesenchimal interactions.

International audience; The present study proposes equations for age determination both in living and dead children, obtained with the help of stepwise ascending multiple linear regression. The equations should be applied, based on the number of erupted teeth and tooth germs, which were detected on radiographs, during clinical examination and in infant skeletal remains. The proposed equations proved to be efficient just like Demirjian's method used as a reference today, and permit age estimation till 20 years of age.

Odontogenic anomalies can occur as a result of conjoining or twinning defects. The phenomenon of tooth fusion arises through the union of two normally separated tooth germs and depending upon the stage of development of the teeth at the time of union, it may be either complete or incomplete. Fusion is the union of two normally separated tooth germs resulting in the formation of a single large tooth. The prevalence of this anomaly is