enamel organ and subjacent tooth crown which is developing or submerged. The teeth most often involved are mandibular third molars, maxillary canines, and mandibular premolars. And the cysts usually occur in the second or third decade of life. The treatment of dentigerous cysts-enucleation, marsupialization, and fenestration-is dictated by the size, environmental structures of the lesion, and desirability of conserving involved tooth. Marsupialization is a conservative technique which allows the reduction or elimination of cystic lesion by making it an accessory compartment of the oral cavity in the case where complete enucleation is not desirable. Marsupialization is thought to be the most suitable method of treatment for the conserving of the involved tooth, thus guiding eruption of it. We report the positive outcome got from marsupialization in dentigerous cysts with review of literature.]]>
Bicuspid ; Dentigerous Cyst ; Enamel Organ ; Jaw ; Molar, Third ; Mouth ; Odontogenic Cysts ; Tooth ; Tooth Crown

OBJECTIVETo study role of dental follicle in tooth root development.

METHODSSixteen mandibular first molar dental germs from eight five-day postnatal Balb/c mice were divided into two groups randomly. Dental follicle of germs in one group was undetached and that of another group was removed. Subsequently, each of the germs was separately transplanted to back-muscles of adult nude mice. At seventh and fourteenth day after transplanting, the germs were collected, fixed, demineralized, dehydrated, and embedded in wax in sequence. Serial sections of 5 microm thick were made following the routine methods, stained with haematoxylin-eosin dying solution, and observed under a light microscope.

RESULTSAll implantations were located in the back-muscles with abundant capillary vasculature. Under microscope, although all tooth germs could further develop after grafting, tooth germs without dental follicle developed slowly with small size and low calcification compared to those with dental follicle. Although position of Hertwig's epithelial root sheath of all germs seemed no changing, roots of the group with dental follicle could further develop and the roots develop toward the apical direction; this tendency couldn't be seen in the germs of another group. Inflammatory cells could be seen in and out of the pulp cavity of the two groups at 7th day after grafting, while no obvious inflammatory cell was observed at 14th day after grafting.

CONCLUSIONDental follicle play an important role in tooth root development. It probably can lead tooth root to develop in normal direction.

Animals ; Dental Pulp Cavity ; Dental Sac ; Enamel Organ ; Mice ; Mice, Nude ; Molar ; Odontogenesis ; Tooth ; Tooth Germ ; Tooth Root

Ameloblastomas and adenomatoid odontogenic tumors (AOTs) are common epithelial tumors of odontogenic origin. Ameloblastomas are clinico-pathologically classified into solid/multicystic, unicystic, desmoplastic, and peripheral types, and also divided into follicular, plexiform, acanthomatous, granular types, etc., based on their histological features. Craniopharyngiomas, derived from the remnants of Rathke's pouch or a misplaced enamel organ, are also comparable to the odontogenic tumors. The malignant transformation of ameloblastomas results in the formation of ameloblastic carcinomas and malignant ameloblastomas depending on cytological dysplasia and metastasis, respectively. AOTs are classified into follicular, extrafollicular, and peripheral types. Ameloblastomas are common, have an aggressive behavior and recurrent course, and are rarely metastatic, while AOTs are hamartomatous benign lesions derived from the complex system of the dental lamina or its remnants. With advances in the elucidation of molecular signaling mechanisms in cells, the cytodifferentiation of epithelial tumor cells in ameloblastomas and AOTs can be identified using different biomarkers. Therefore, it is suggested that comprehensive pathological observation including molecular genetic information can provide a more reliable differential diagnosis for the propagation and prognosis of ameloblastomas and AOTs. This study aimed to review the current concepts of ameloblastomas and AOTs and to discuss their clinico-pathological features relevant to tumorigenesis and prognosis.
Ameloblastoma ; Ameloblasts ; Biomarkers ; Cell Transformation, Neoplastic ; Craniopharyngioma ; Diagnosis, Differential ; Enamel Organ ; Molecular Biology ; Neoplasm Metastasis ; Odontogenic Tumors ; Prognosis

enamel organ, remnants of dental lamina, or the lining of an odontogenic cyst. It is usually categorized into solid or multicystic, unicystic, and peripheral types. Treatment ofameloblastomas include conservative methods such as marsupialisation, enucleation, and curettage; and radical treatments such as marginal or segmental resection. Radical treatments have resulted in lower recurrence rates; however, may also encounter esthetic, functional, and reconstructive problems. Unicystic ameloblastoma has been considered less aggressive and a lower recurrence tendency. Thus, many authors have recommended conservative treatment in cases of unicystic ameloblastoma. An 11 year-old boy presented with displaced second and third molars by luminal unicystic ameloblastoma in the mandible. Cyst enucleation, curettage, and third molar extraction were done. No signs of recurrence or esthetic problems such as facial asymmetry were seen radiologically and clinically, up to 8 years 2 months postoperatively.]]>
Ameloblastoma ; Curettage ; Enamel Organ ; Facial Asymmetry ; Mandible ; Molar ; Molar, Third ; Odontogenic Cysts ; Phenobarbital ; Recurrence ; Tooth ; Tooth, Impacted

OBJECTIVE: To investigate the regulation mechanism of RhoA signaling pathway during the enamel formation by using the EGFP-RhoA^{Dominant Negative} (EGFP-RhoA^DN) transgenic mice model, from the aspect of adherens junctions, and to provide a theory basis for mechanism of enamel development defects. METHODS: The enamel thickness of mandibular first molars of EGFP-RhoA^DN transgenic mice and wild type (WT) mice were observed by scanning electronic microscopy at 20 kV, and the enamel thickness of the distal face of the central cusp was measured at 10 locations via analysis by ImageJ (Rasband, 1997-2009). The enamel organs from mandibular first molars from postnatal-4-day (P4) EGFP-RhoA^DN mice and wild type mice were isolated, and the total RNA and protein were extracted from the epithelium of the enamel organs. The expression level of the adherens junctions components in ameloblasts layer of the postnatal-4-day EGFP-RhoA^DN transgenic mice and wild type mice mandibular first molars were detected by real-time PCR and Western blot assay. RESULTS: The EGFP-RhoA^DN transgenic mice had decreased enamel thickness in their bilateral mandibular first molars versus those of control group (n=20), and enamel thickness was (84.60±0.20) μm vs. (106.24±0.24) μm, P<0.05. The protein expressions of E-cadherin, α-E-catenin and pan-cadherin in ameloblasts layer of postnatal-4-day EGFP-RhoA^DN transgenic mice molars were down-regulated, and the protein level of β-catenin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was up-regulated. The mRNA level of E-cadherin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was down-regulated versus that of WT mice, and the gene expression of E-cadherin was 0.93±0.01 vs. 1.00±0.02, P<0.05. The mRNA level of β-catenin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was up-regulated versus that of WT mice, and the gene expression of β-catenin was 1.23±0.03 vs. 1.00±0.05, P<0.05. CONCLUSION In the mandibular first molars of EGFP-RhoA^DN transgenic mice, the enamel formation was disrupted and the adherens junctions of EGFP-RhoA^DN transgenic mice ameloblasts were implicated during amelogenesis. RhoA signaling pathway may play a critical role in enamel development by altering the adherens junctions in ameloblasts.
Adherens Junctions ; Ameloblasts ; Amelogenesis ; Animals ; Antigens, CD ; Cadherins/metabolism* ; Dental Enamel/metabolism* ; Enamel Organ ; Humans ; Mice ; Mice, Transgenic ; Molar ; Signal Transduction ; alpha Catenin ; beta Catenin ; rhoA GTP-Binding Protein/physiology*

Objectives : The proper development of the facial structures relies upon a sequence of tightly regulated signaling interactions between the ectoderm and mesoderm involving the participation of several families of signaling molecules. Among these, bone morphogenetic proteins (BMPs) have been suggested to be a key signal that regulates the development of the mandible and the initiation and morphogenesis of the teeth. The aim of this study was to examine the artificial development of the mandibular structures and to examine the role of BMPs on tooth morphogenesis and differentiation using an organ culture system. Materials and Methods : The tooth germs from Ed 11.5, 13.5 mice were dissected, and transplanted into the diastema of the mandible primordia. The mandibles containing the transplanted tooth germs were cultured in vitro. During this period, beads soaked with BMP4 were implanted around the transplanted tooth germs. In addition, a diastema block containing the transplanted tooth germ was dissected, then transferred to an adult mouse kidney. After the organ culture, the developing mandibular explant was removed from the kidney and prepared for the tissue specimens. Odontogeneis of the transplanted tooth germs was examined after Hematoxylin-eosin, Masson-trichrome staining. Results : Proliferation and differentiation of the tooth germs cultured in the diastema was observed. In the BMP4-treated tooth germs, the formation of the first and second molars was noted. The crown of the developing tooth showed the formation of a mature cusp with the deposition of enamel and dentin matrix. In conclusion, it was confirmed that BMP4 is involved in the formation of a dental crown and the differentiation of ameloblasts and odontoblasts of the molar tooth during the development of the transplanted tooth germs.
Adult ; Ameloblasts ; Animals ; Bone Morphogenetic Proteins* ; Crowns ; Dental Enamel ; Dentin ; Diastema ; Ectoderm ; Humans ; Kidney ; Mandible ; Mesoderm ; Mice ; Molar ; Morphogenesis ; Odontoblasts ; Organ Culture Techniques ; Tooth Germ ; Tooth*

Osteocalcin (OC) is the most abundant noncollagenous protein of extracellular matrix in the bone. In an OC deficient mouse, bone formation rates are increased in cancellous and cortical bones. OC is known as a negative regulator of mineral apposition. OC is also expressed in the tooth of the rat, bovine, and human. However, little is known about OC during tooth development in Xenopus. The purpose of this study is to compare the expression of OC with mineralization in the developing tooth of Xenopus, by using von Kossa staining and in situ hybridization. At stage 56, the developmental stage of tooth germ corresponds to the cap stage, and an acellular zone was apparent between the dental papilla and the enamel organ. From stage 57, calcium deposition was revealed by von Kossa staining prior to OC expression, and the differentiated odontoblasts forming predentin were located at adjoining predentin. At stage 58, OC transcripts were detected in the differentiated odontoblasts. At stage 66, OC mRNA was expressed in the odontoblasts, which was aligned in a single layer at the periphery of the pulp. These findings suggest that OC may play a role in mineralization and odontogenesis of tooth development in Xenopus.
Animals ; Calcium ; Dental Papilla ; Enamel Organ ; Extracellular Matrix ; Humans ; In Situ Hybridization ; Mice ; Odontoblasts ; Odontogenesis ; Osteocalcin* ; Osteogenesis ; Rats ; RNA, Messenger ; Tooth Germ ; Tooth* ; Xenopus ; Xenopus laevis*

OBJECTIVETo investigate the effects of lead exposure at different levels in utero on the teeth eruption and enamel development of rat offsprings.

METHODS27 pregnant SD rats were divided into three groups randomly: high level lead group (HLG), low level lead group (LLG) and control group with nine rats in each group. The three groups from the gestation day to the end of the gestation were given either deionized water in control group or deionized water containing 200 mg/L Pb2+ as lead acetate through drinking method in high level lead experimental group and 50 mg/L Pb2+ as lead acetate through drinking method in low level lead experimental group. The incisors of newborn rats were marked at the level of the gingival papilla on the 26th day after birth. On the 36th day, the incisors of newborn rats were marked again at the same level. Then the rat offsprings were killed and their blood was collected for lead analysis. The mandible incisors of rat offspring were separated and the content of Pb in incisors was determined by using a graphite furnace atomic absorption spectrometric method. The teeth of rat offspring were observed and the distance between two marks were measured by means of stereomicroscope. The ratio of calcium to phosphate of enamel of rat offspring was compared by electron probe microanalyses.

RESULTSThe level of blood lead in 200 mg/L, 50 mg/L treated rat offspring groups was higher than that in control group. The tooth lead of 200 mg/L, 50 mg/L treated rat offspring groups [(77.3 +/- 6.3), (27.8 +/- 4.5) microg/g] were higher than the control [(6.6 +/- 0.8) microg/g, P < 0.01]. Compared with the control group, the teeth of lead exposure experimental groups were smaller and severity of attrition was obvious and pulpal perforations were often observed. These appearances was more distinct in rats of high level lead experimental group. The incisors of lead-treated rat offspring erupted [(0.25 +/- 0.08), (0.30 +/- 0.09) mm/d] more slowly than control ones [(0.39 +/- 0.09) mm/d, P < 0.01]. The ratio of calcium to phosphate (Ca/P) decreased with the increase of lead exposure. It was found that Ca/P in lead exposure experimental groups (1.68 +/- 0.54), (1.37 +/- 0.47) was significantly lower than that in the control group (2.14 +/- 0.33).

CONCLUSIONLead exposure in utero affects the normal eruption of teeth and enamel formation and the degree was related with the lead exposure level.

Animals ; Enamel Organ ; drug effects ; Female ; Lead ; adverse effects ; Maternal Exposure ; adverse effects ; Pregnancy ; Prenatal Exposure Delayed Effects ; pathology ; Rats ; Rats, Sprague-Dawley ; Tooth Eruption ; drug effects

Hertwig's epithelial root sheath (HERS) consists of bilayered cells derived from the inner and outer dental epithelia and plays important roles in tooth root formation as well as in the maintenance and regeneration of periodontal tissues. With regards to the fate of HERS, and although previous reports have suggested that this entails the formation of epithelial rests of Malassez, apoptosis or an epithelialmesenchymal transformation (EMT), it is unclear what changes occur in the epithelial cells in this structure. This study examined whether HERS cells undergo EMT using a keratin-14 (K14) cre:ROSA 26 transgenic reporter mouse. The K14 transgene is expressed by many epithelial tissues, including the oral epithelium and the enamel organ. A distinct K14 expression pattern was found in the continuous HERS bi-layer and the epithelial diaphragm were visualized by detecting the beta-galactosidase (lacZ) activity in 1 week postnatal mice. The 2 and 4 week old mice showed a fragmented HERS with cell aggregation along the root surface. However, some of the lacZ-positive dissociated cells along the root surface were not positive for pan-cytokeratin. These results suggest that the K14 transgene is a valuable marker of HERS. In addition, the current data suggest that some of the HERS cells may lose their epithelial properties after fragmentation and subsequently undergo EMT.
Animals ; Apoptosis ; beta-Galactosidase ; Cell Aggregation ; Diaphragm ; Enamel Organ ; Epithelial Cells ; Epithelial-Mesenchymal Transition ; Epithelium ; Keratin-14 ; Mice ; Regeneration ; Tooth ; Tooth Root ; Transgenes

enamel organ, the dental papilla, and the dental follicle. The dental papilla lies below a cellular aggregation of the enamel organ. Mesenchymal cells within the dental papilla are responsible for formation of dentin and pulp of a tooth. Tooth germ disappears as a tooth is formed, but that of a third molar stays in the jawbone of a human until the age of 10 to 16, because third molars grow slowly. Impacted third molar tooth germs from young adults are sometimes extracted for orthodontic treatment. In the present study, we evaluated the osteogenic activity and mineralization of cultured human dental papilla-derived cells. Dental papillas were harvested from mandible during surgical extraction of lower impacted third molar from 3 patients aged 13-15 years. After passage 3, the dental papilladerived cells were trypsinized and subsequently suspended in the osteogenic induction DMEM medium supplemented with 10% fetal bovine serum, 50 g/ml L-ascorbic acid 2-phosphate, 10 nM dexamethasone and 10 mM -glycerophosphate at a density of 1 x 10(6) cells/dish in a 100-mm culture dish. The dental papilla-derived cells were then cultured for 6 weeks and the medium was changes every 3 days during the incubation period. Dental papilla-derived cells showed positive alkaline phosphatase (ALP) staining during 42 days of culture period. The formation of ALP stain showed its maximal manifestation at day 7 of culture period, then decreased in intensity during the culture period. ALP mRNA level was largely elevated at 1 weeks and gradually decreased with culture time. Osteocalcin mRNA expression appeared at day 14 in culture, after that its expression continuously increased in a time-dependent manner up to day 28. The expression remained constant thereafter. Runx2 expression appeared at day 7 with no detection thereafter. Von Kossa-positive mineralization nodules were first present at day 14 in culture followed by an increased number of positive nodules during the entire duration of the culture period. Osteocalcin secretion was detectable in the culture medium from 1 week. The secretion of osteocalcin from dental papilla-derived cells into the medium greatly increased after 3 weeks although it showed a shallow increase by then. In conclusion, our study showed that cultured human dental papilla-derived cells differentiated into active osteoblastic cells that were involved in synthesis of bone matrix and the subsequent mineralization of the matrix.]]>
Alkaline Phosphatase ; Ascorbic Acid ; Bone Matrix ; Dental Papilla ; Dental Sac ; Dentin ; Dexamethasone ; Enamel Organ ; Humans ; Mandible ; Molar, Third ; Osteoblasts ; Osteocalcin ; RNA, Messenger ; Stem Cells ; Tooth ; Tooth Germ ; Trypsin ; Young Adult