Self-drilling screws for the prevention of dental and skeletal injuries during open reduction and internal fixation of pediatric mandibular fractures

Facial trauma in pediatric population predisposes the child to injury of both the developing skeleton and dentition. This article aims to highlight the experience of the authors through a case report, in using self-drilling screws for fixation of mandibular fractures in pediatric age group. The use of self-drilling screws minimizes the complications such as thermal and/or mechanical damage to the developing dentition and the bone. They also provide significant advantages including ease of availability and technique, superior anchorage with primary stability, and minimizing or avoiding permanent damage to the developing tooth germs in the site of fracture. The use of self-drilling screws for mandibular open reduction and internal fixation in children is an easy, reliable, and safe technique which may have significant value addition in preventing inadvertent injury to the developing tooth germs.

Early loss of primary molar and permanent tooth germ caused by the use of devitalizer during primary molar root canal therapy: Two cases report / 北京大学学报(医学版)

Devitalization has been widely used in the root canal therapy of primary and permanent teeth in China more than ten years ago. With the development of local anesthetic drugs and injection technologies, this treatment method with high potential risks has been gradually abandoned. However, a questionnaire survey targeted all the participants at the 2018 China Pediatric Dentistry Conference showed that the devitalizer utilization proportion was still as high as 38.1% (383/1 005), even though the ratio was much lower than 75.5% (105/139) in 2003. These doctors had pay more attention to tissue burn caused by devitalizer marginal leakage or direct leakage, and know how to identify and handle with devitalizer burn. Devitalizers were usually made of arsenic trioxide, metal arsenic or paraformaldehyde, which have cytotoxicity, allergenicity, mutagenicity, carcinogenicity, and teratogenic effects on animals. Marginal leakage of devitalizers have high risks of causing soft and hard tissue necrosis. Most of the dentists have an understanding of the potential damages of arsenic containing devitalizers, so they will choose parafor maldehyde with relatively less toxicity. Paraformaldehyde has a certain self limitation, and there are few cases reported, so some dentists lack of vigilance. Paraformaldehyde can also causes tissue necrosis if leakage happens, and the treatment methods are similar to that of arsenic containing devitalizers. When handling with devitalizers burn, the necrosed soft and hard tissue, for example gingiva, alveolar bone or teeth that cannot keep, must be completely removed until fresh blood appears, then rinse with large amount of saline and seal with iodoform gauze. This paper described two cases of devitalizer burn during the root canal treatment of primary molars, both of the doctors failed to identify the devitalizer burn symptoms in the early stage, thus didn't do proper treatments immediately after burning. Resulting in the necrosis of large area of gingiva and alveolar bone, loss of primary molars and permanent tooth germs 1-2 months after devitalizer burn. This paper reported these two cases in detail in order to warn dentists the high risks of using any kind of devitalizers, help them learn how to identify and treat devitalizer burn, and remind them to stop using devitalizers as soon as possible.

Immunohistochemical localization of vascular factors in tooth germ of amphibian (Cynops pyrrhogaster) / Localización inmunohistoquímica de factores vasculares en germen dentario de anfibios (Cynops pyrrhogaster)

SUMMARY: Vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2, are known to regulate blood vessel endothelium growth. They play important role in human and rodents teeth development. In newt jaws, there are sequential developmental teeth germs following behind the mature teeth. We examined the immunohistochemical localization of VEGF and its receptor and showed the specific expression pattern of VEGF and VEGF receptor in Cynops pyrrhogaster sequential tooth development. The intensity of immunoreactivity for VEGF in the inner enamel epithelium was weaker than that in the outer enamel epithelium in the dentine matrix formation and mineralization stages. Finally, at the enameloid maturation and enamel-like matrix formation stage, immunoreactivity for VEGF in inner enamel epithelium was stronger than in the outer enamel epithelium. The intensity of immunoreactivity for VEGFR-2 was positive for the outer enamel epithelium throughout tooth development. The crown sides of the odontoblasts were stained especially strongly for VEGF and VEGFR-2 during the dentine matrix formation and mineralization stage of the enameloid maturation and enamel- like matrix formation stage. We postulate that the expression of VEGF in the inner enamel epithelium and odontoblast widely effects tooth development in newts, as well as in human and rodents.

RESUMEN: Se sabe que el factor de crecimiento endotelial vascular (VEGF) y su receptor, VEGFR-2, regulan el crecimiento del endotelio de los vasos sanguíneos. Desempeñan un papel importante en el desarrollo de los dientes humanos y de los roedores. En las mandíbulas de tritón, hay gérmenes dentales de desarrollo secuenciales que siguen a los dientes maduros. Examinamos la localización inmunohistoquímica de VEGF y su receptor y mostramos el patrón de expresión específico de VEGF y receptor de VEGF en el desarrollo secuencial de dientes de Cynops pyrrhogaster. La intensidad de la inmunorreactividad para VEGF en el epitelio interno del esmalte era más débil que en el epitelio externo del esmalte en las etapas de formación y mineralización de la matriz de dentina. Finalmente, en la etapa de maduración del esmalte y de formación de la matriz similar al esmalte, la inmunorreactividad para VEGF en el epitelio interno del esmalte fue más fuerte que en el epitelio externo del esmalte. La intensidad de la inmunorreactividad para VEGFR- 2 fue positiva para el epitelio externo del esmalte durante el desarrollo del diente. Los márgenes de la corona de los odontoblastos se tiñeron especialmente para VEGF y VEGFR-2 durante la etapa de formación de la matriz de dentina y mineralización de la etapa de maduración del esmalte y la etapa de formación de la matriz similar al esmalte. Postulamos que la expresión de VEGF en el epitelio interno del esmalte y odontoblastos afecta ampliamente el desarrollo de los dientes en tritones, así como en humanos y roedores.

The effect of inhibiting p38 MAPK on the expression of genes related to enamel development in mice / 口腔疾病防治

Objective@#To study the effect of p38 mitogen activated protein kinase (p38 MAPK) on the expression of genes related to enamel development in the enamel epithelium and to provide a basis for the study of the molecular mechanism of enamel development.@*Methods@#The p38 MAPK-specific inhibitor SB203580 dissolved in DMSO was added to the culture medium of mouse mandibular molar tooth germs in vitro as experiment group, and mouse mandibular molar tooth germs treated with the same amount of DMSO were used as control group. Western blot was used to detect the protein expression level of phosphorylated p38 (p-p38) in the enamel epithelium. Real-time PCR was used to detect the mRNA expression levels of runt-related transcription factor 2 (Runx2), osteoblast-specific transcription factor (Osx), ameloblast markers odontogenic ameloblast associated protein (ODAM), amelotin (AMTN), matrix metalloproteinase 20 (MMP20) and kallikrein 4 (KLK4) in the enamel epithelium. @*Results @# Western blot results showed that under the action of the inhibitor SB203580, the phosphorylation level of p38 MAPK in mouse enamel epithelium decreased, and the difference was statistically significant (P < 0.05). Real-time PCR results showed that the expression levels of the transcription factors Runx2 and Osx and the ameloblast markers ODAM, AMTN, MMP20, and KLK4 in the SB203580 group were lower than those in the control group, and the difference was statistically significant (P < 0.05).@*Conclusion@#The p38 MAPK signaling pathway can mediate enamel development by regulating the expression of the transcription factors Runx2 and Osx and the ameloblast markers ODAM, AMTN, MMP20 and KLK4 in the mouse enamel epithelium.

Spatio-temporal expression of dentin sialophosphoprotein and collagen Ⅰ during molar tooth germ development in vps4b knockout mouse / 华西口腔医学杂志

OBJECTIVE@#To verify the effect of the mutant gene vps4b on the expression of tooth development-related proteins, dentin sialophosphoprotein (DSPP) and collagenⅠ (COL-Ⅰ).@*METHODS@#Paraffin tissue sections of the first molar tooth germ were obtained from the heads of fetal mice at the embryonic stages of 13.5, 14.5, and 16.5 days and from the mandibles of larvae aged 2.5 and 7 days after birth. The immunohistochemical method was used to detect the expression and location of DSPP and COL-Ⅰ in wild-type mouse and vps4b knockout mouse.@*RESULTS@#DSPP and COL-Ⅰ were not found in the bud and cap stages of wild-type mouse molar germ. In the bell stage, DSPP was positively expressed in the inner enamel epithelium and dental papilla, whereas COL-Ⅰ was strongly expressed in the dental papilla and dental follicle. During the secretory and mineralized periods, DSPP and COL-Ⅰ were intensely observed in ameloblasts, odontoblasts, and dental follicles, but COL-Ⅰ was also expressed in the dental papilla. After vps4b gene knockout, DSPP was not expressed in the dental papilla of the bell stage and in the dental papilla and dental follicle of the secretory phase. The expression position of COL-Ⅰ in the bell and mineralization phase was consistent with that in the wild-type mice. Moreover, the expression of COL-Ⅰ in the dental papilla changed in the secretory stage.@*CONCLUSIONS@#Gene vps4b plays a significant role in the development of tooth germ. The expression of DSPP and COL-Ⅰ may be controlled by gene vps4b and regulates the development of tooth dentin and cementum together with vps4b.

Structural characteristics of the deciduous teeth of Tibetan miniature pigs / 南方医科大学学报

OBJECTIVE@#To explore the histological structure of the deciduous teeth and the tooth germs of Tibetan miniature pigs for studies of dental tissue diseases and tooth regeneration.@*METHODS@#The structure of the deciduous teeth of Tibetan miniature pigs was observed by X-ray. The ultrastructure of the enamel and dentin of deciduous teeth was characterized by scanning electron microscopy. The jaws and teeth were three-dimensionally reconstructed using Mimics software based on Micro-CT scanning of the deciduous teeth. Image J software was used to calculate the gray value and the mineralization density of the deciduous teeth. Hisotological structure of the tooth germ and the pulp tissue of Tibetan miniature pigs was observed using HE staining.@*RESULTS@#The deciduous teeth of Tibetan miniature pigs were composed of enamel, dentin and medullary pulp tissue. The permanent tooth germ were formed during the deciduous dentition. The enamel and dentin ultrastructure of deciduous teeth were consistent with that of human deciduous teeth. The enamel and dentin mineralization densities were 2.47±0.09 g/cm and 1.72±0.07 g/cm, respectively. The pathological structures of tooth germ and pulp tissue were similar to those of human teeth, and the pulp tissue of the deciduous teeth was in an undifferentiated state.@*CONCLUSIONS@#The deciduous teeth of Tibetan miniature pig have similar anatomy, ultrastructure and histopathological structure to human teeth and can serve as a good animal model for studying human dental tissue diseases and the mechanisms of tooth regeneration.

Expressions of cell polarity related proteins CDC42and PAR3 during tooth germ development in mice / 吉林大学学报(医学版)

Objective:To study the expressions of cell polarity related proteins CDC42 and PAR3 during tooth germ development in the mice,and to discuss their possible roles during tooth development in the mice.Methods:The whole heads were obtained from the mouse embryo on the days 13.5,14.5,16.5 and 18.5 (E13.5,E14.5,E16.5 and E18.5) and the mice on the postnatal days 1 (PN1) and 5 (PN5).The tissues were fixed in paraformaldehyde,decalcified,dehydrated,embedded in paraffin,and sectioned.The histology of tooth germ was observed by HE staining.The expressions of CDC42 and PAR3 during tooth germ development were detected by immunohistochemistry staining.Results:The HE staining results showed that E13.5,E14.5,E16.5 and E18.5were the bud stage,the cap stage,the early and the late bell stage of tooth germ development,respectively;the tooth germ of PN1 mice showed the matured odontoblasts and ameloblasts;the tooth germ of PN5 mice showed the completed tooth crown development.The immunohistochemistry staining results showed that CDC42 expressed in the tooth germ of the mice at E13.5,E14.5 and E16.5;the CDC42 expression at E 18.5 was reduced compared with E13.5,E14.5 and E16.5;CDC42 mainly expressed in the odontoblasts and ameloblasts of the tooth germ of the mice at PN1 and PN5;PAR3 weakly expressed in the tooth germ of the mice at E13.5 and E14.5,and it was increased at E16.5 and E18.5.At PN1 and PN5,the expressions of PAR3 were decreased compared with E18.5.Conclusion:CDC42 and PAR3 partieipat in the mouse tooth development;during the early stage of tooth germ development,they may be involved in the proliferation and migration of mouse dental germ;during the late stage,CD42 and PAR3 may be involved in the differentiation of the odontoblasts and the ameloblasts,especially in the establishment and maintenance of cell polarity.

Expressions of cell polarity related proteins CDC42 and PAR3 during tooth germ development in mice / 吉林大学学报(医学版)

Objective: To study the expressions of cell polarity related proteins CDC42 and PAR3 during tooth germ development in the mice, and to discuss their possible roles during tooth development in the mice. Methods: The whole heads were obtained from the mouse embryo on the days 13. 5, 14. 5, 16. 5 and 18. 5 (E13. 5, E14. 5, E16. 5 and E18. 5) and the mice on the postnatal days 1 (PN1) and 5 (PN5). The tissues were fixed in paraformaldehyde, decalcified, dehydrated, embedded in paraffin, and sectioned. The histology of tooth germ was observed by HE staining. The expressions of CDC42 and PAR3 during tooth germ development were detected by immunohistochemistry staining. Results: The HE staining results showed that E13. 5, E14. 5, E16. 5 and E18. 5 were the bud stage, the cap stage, the early and the late bell stage of tooth germ development, respectively; the tooth germ of PN1 mice showed the matured odontoblasts and ameloblasts; the tooth germ of PN5 mice showed the completed tooth crown development. The immunohistochemistry staining results showed that CDC42 expressed in the tooth germ of the mice at E13. 5, E14. 5 and E16. 5; the CDC42 expression at E 18. 5 was reduced compared with E13. 5, E14. 5 and E16. 5; CDC42 mainly expressed in the odontoblasts and ameloblasts of the tooth germ of the mice at PN1 and PN5; PAR3 weakly expressed in the tooth germ of the mice at E13. 5 and E14. 5, and it was increased at E16. 5 and E18. 5. At PN1 and PN5, the expressions of PAR3 were decreased compared with E18. 5. Conclusion: CDC42 and PAR3 participat in the mouse tooth development; during the early stage of tooth germ development, they may be involved in the proliferation and migration of mouse dental germ; during the late stage, CD42 and PAR3 may be involved in the differentiation of the odontoblasts and the ameloblasts, especially in the establishment and maintenance of cell polarity.

Analisis inmunohistoquimico de CK14 y CK19 en germen dentario y ameloblastoma / Immunohistochemical analysis of ck14 and ck19 in tooth germs and ameloblastoma

La odontogénesis es el proceso de formación de los órganos dentarios, en el cual se expresan diversas moléculas, dentro de las cuales encontramos las citoqueratinas 14 y 19 (CK14, CK19). Una vez concluido el proceso de formación del diente quedan restos del epitelio odontogénico, el cual se ha sugerido se encuentra implicado en el desarrollo del ameloblastoma, uno de los tumores odontogénicos más frecuentes. Se ha sugerido que las CK14 y CK19 tienen utilidad como marcadores de diferenciación ameloblástica, y podrían tener implicación dentro del comportamiento tumoral de los ameloblastomas. El objetivo del presente estudio fue describir los patrones de expresión inmunohistoquímica de estas dos citoqueratinas en gérmenes dentarios y ameloblastomas. Materiales y métodos. Se incluyeron 6 ameloblastomas sólidos multiquísticos y 5 gérmenes dentarios a los cuales se les realizó técnica de inmunohistoquímica para CK14 y CK19. Resultados. Este estudio permitió visualizar la inmunoexpresión de CK14 y CK19 en el epitelio y la negatividad en el ectomesénquima, tanto en los gérmenes dentarios como en ameloblastomas. También permitió concluir que CK19 puede ser considerada como un eficiente marcador de diferenciación ameloblástica, mientras que CK14 es gradualmente remplazada por CK19 en el epitelio interno del órgano del esmalte, evidenciándose marcada inmunoexpresión de esta última en ameloblastos secretores...

Introduction. Odontogenesis is the process by which teeth form, and where different molecules are expressed, among them some cytokeratins (CK) like CK14 and CK19. Remnants of odontogenic epithelium may persist once the development process is complete, which has been suggested to be involved in the development of ameloblastoma, one of the most common benign odontogenic tumours. It has been suggested that CK14 and CK19 are useful markers of ameloblast differentiation and that they could have implications for tumour behaviour. The aim of this study is to describe the patterns of immunohistochemical expression of these cytokeratins in tooth germs and ameloblastomas. Materials and methods. We worked with 6 solid multicystic ameloblastomas and 5 tooth germs. The immunohistochemistry technique was used to visualise CK14 and CK19. Results. We detected CK14 and CK19 immunoexpression in the epithelium and no expression in the ectomesenchyme in both tooth germs and ameloblastomas. It was concluded that CK19 can be considered an efficient marker of ameloblast differentiation, whereas CK14 is gradually replaced by CK19 in the inner epithelium of the enamel organ, showing strong immunoexpression in secretory ameloblasts...

Spatiotemporal expression pattern of E-cadherin and P-cadherin during mouse tooth development / 北京大学学报(医学版)

Objective:To investigate the expression patterns of E-cadherin and P-cadherin in murine-tooth germs at early developmental stages .Methods:Mandible samples of CD 1 mice from embryonic day 12 .5 to postnatal day 3 .5 were collected .The expressions of E-cadherin and P-cadherin in murine man-dibular first molar germs were detected by immunofluorescence and observed under confocal fluorescence microscope .HE staining was performed for tissue morphology .Results:Both E-cadherin and P-cadherin were widely expressed in the epithelial tissues through early developmental stages .The E-cadherin ex-pression was increased in polarizing pre-ameloblasts , whereas the P-cadherin expression declined .The expression of the P-cadherin could be detected in epithelial tissues before bud stage , and expressed in mature ameloblasts at secretory stage .Conclusion:The E-cadherin and P-cadherin expressed in different spatiotemporal expression patterns , indicating their individual functions during tooth development .P-cad-herin might function in the secretion and mineralization of enamel .

The effect of two different odontoblast inducer on the proliferation and apoptosis of rat adiposed-derived stem cells / 重庆医学

Objective To investigate the effect of two different odontoblast inducer on the proliferation and apoptosis of rat adiposed-derived stem cells.Methods Adiposed-derived stem cells were collected by enzyme digestion from inguinal fat pads of 4 days post natal mice.Immunocytochemistry was performed to identify the cells.MTT and flow cytometry were tested the prolifera-tion and apotosis of adiposed-derived stem cells by co-cultured with tooth germ cell conditioned medium(TGC-CM)or dentin non-collagenous protein medium (DNCPM).Results Cells displayed a fibroblast-like appearance and positively expressed CD44 and CD105 when cufured to the secend yeneration.After 3 day the cells polarity changed by co-cultured.Count of cells were no obvious change by TGC-CM co-cultured,while that ruduced significantly by DNCPM co-cultured.It confirmed that the proliferation rate of ADSCs in TGC-CM group and control group is higher than DNCPM group(P 0.05).Conclusion TGC-CM may have more advantage as inducer in rat adiposed-derived stem cells differentiate into dentin like cells than DNCPM.

Comparative development of mouse tooth germs transplanted in subrenal capsule and oral submucosa / 中国病理生理杂志

AIM:To compare 2 environments , the subrenal capsule and oral submucosa , for producing well-formed teeth from mouse tooth germs and for exploring the ideal environment for tooth regeneration .METHODS: Two groups were set up .Group A was transplanted with the mouse embronic day ( ED) 14.5 first mandibular molar tooth germs into the subrenal capsule , while group B was transplanted with the ED 14.5 first mandibular molar tooth germs into the oral submucosa.After 3 weeks and 4 weeks, the host mice were sacrificed, and the transplanted explants were evaluated with morphologic observation , histological structures , hardness and elastictic modulus tests , and chemical compositions .RE-SULTS:(1) The explants isolated from both environments showed the tooth-like structures, but as to the group B, the crown was smaller, and the shape of the cusps was not significant .(2) HE staining showed that the dentin and enamel in group A were thicker than those in group B in which the ameloblasts and odontoblasts were differentiated not very well .(3) In the test of enamel hardness , only the hardness of 4 weeks in group B was lower than normal mouse tooth .In the test of enamel modulus , the elastic modulus of enamel in 3 weeks of group A was slightly lower than normal mouse tooth , but the difference was not significant .The elastic modulus of enamel in 4 weeks of group A and group B was significantly lower than normal mouse tooth and 3 weeks of group B .The hardness and elastic modulus of dentin in 3 groups was not significant . (4) Raman spectroscopy showed 2 groups grew in harmony in general , they all had the largest peak in the point of 961 cm-1 , but the 3 weeks of group B had an obvious peak in the point of 2 947 cm-1 .CONCLUSION:For the development of ED14.5 tooth germs, we obtain almost the whole tooth in subrenal capsule transplantation after 3 or 4 weeks.The buccal submucosa environment still has a certain influence on the tooth germ development , although there are some differences about the tooth development between this environment and subrenal capsule environment .

Odontogenesis-related gene expression during in vitro culture of tooth germ cells / 中国组织工程研究

BACKGROUND:Some studies have indicated that different genes in tooth germ tissue play a role at different time, contributing to tooth germ development. OBJECTIVE:To observe the expressions of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 at different stage of in vitro culture of tooth germ cells. METHODS:RNA from tooth germ cells was extracted at days 1, 3, 6 of in vitro culture. After reverse transcription, real-time quantitative PCR detection was adopted to measure relative expression of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 mRNA. RESULTS AND CONCLUSION:Dentin matrix protein 1, enamel protein, and col agen I mRNA expressions increased with culture time, and reached the peak at day 3 (P<0.05), whereas homeobox gene 1 mRNA decreased with culture time (P<0.05).

An Immune-compromised Method for Tooth Transplantation Using Adult Bone Marrow Stromal Cells and Embryonic Tooth Germ / 체질인류학회지

Tooth transplantation using autogenic adult teeth or embryonic tooth germs is the one of best treatments for replacement of missing teeth, but there are limitations in the accessibility. Isogenic or xenogenic tooth transplantation has been failed because of the immune rejection response occurring in the periodontal ligament of transplanted tooth. In this study, by utilizing the recombination between mouse embryonic tooth germ and mouse adult bone marrow stromal cells, we tried to replace the periodontal tissues such as periodontal ligament and alveolar bone with adult bone marrow stromal cells. At four weeks after the transplantation of the recombinant into a kidney, adult bone marrow-derived cells cells were observed in the periodontal ligament and alveolar bone. This result indicates that adult bone marrow stromal cells can participate in the formation of periodontal tissues. If these tooth and periodontal tissues are transplanted into host who donates adult bone marrow stromal cells, adult bone marrow-derived cells will be regarded as host cells, and immune rejection response will not occur in these cells. Therefore, it is suggested that recombination between adult bone marrow stromal cells and embryonic tooth germ is a good candidate method using xenogenic tooth germ for replacement of missing teeth in human by replacing cells in periodontal tissues with human adult bone marrow stromal cells.

Morphological analysis of the enamel organ in rats treated with fluoxetine

Purpose: Previous studies have evaluated the presence of serotonin in the dental epithelia and mesenchyme during odontogenesis, suggesting its participation in tooth development. Materials and methods: Here, we used fluoxetine, a selective serotonin re-uptake inhibitor, at a dose of 10 mg/kg, administered for 20 days during pregnancy in 12 Wistar rats to examine the influence of this drug on the development of the enamel organ of the upper first molars of rat fetuses at 17 days of intra-uterine life (i.u.l.), and at one, five and ten days postpartum. The pregnant rats were anesthetized with xylazine at 10 mg/kg and ketamine at 25 mg/kg. The fetuses were removed and beheaded; their jaws were removed, and the upper jaws were exposed. The tissues were fixed in Bouin's fixative, decalcified in 5 percent nitric acid for 4 - 12 h, conventionally processed for microscopy, and embedded in paraffin. Serial sections of approximately 5 mm were obtained and stained with hematoxylin and eosin, as well as periodic acid-Schiff. Results and conclusion: Morphological analysis showed no structural changes in the experimental group compared to the controls, suggesting that, at the dose used, fluoxetine does not interfere with serotonin-mediated development of the enamel organ or the process of amelogenesis.

Cholinesterase Activity in the Dental Epithelium of Hamsters During Tooth Development

Cholinesterase (ChE) is one of the most ubiquitous enzymes and in addition to its well characterized catalytic function, the morphogenetic involvement of ChE has also been demonstrated in neuronal tissues and in non-neuronal tissues such as bone and cartilage. We have previously reported that during mouse tooth development, acetylcholinesterase (AChE) activity is dynamically localized in the dental epithelium and its derivatives whereas butyrylcholinesterase (BuChE) activity is localized in the dental follicles. To test the functional conservation of ChE in tooth morphogenesis among different species, we performed cholinesterase histochemistry following the use of specific inhibitors of developing molar and incisors in the hamster from embryonic day 11 (E11) to postnatal day 1 (P1). In the developing molar in hamster, the localization of ChE activity was found to be very similar to that of the mouse. At the bud stage, no ChE activity was found in the tooth buds, but was first detectable in the dental epithelium and dental follicles at the cap and bell stages. AChE activity was found to be principally localized in the dental epithelium whereas BuChE activity was observed in the dental follicle. In contrast to the ChE activity in the molars, BuChE activity was specifically observed in the secretory ameloblasts of the incisors, whilst no AChE activity was found in the dental epithelium of incisors. The subtype and localization of ChE activity in the dental epithelium of the incisor thus differed from those of the molar in hamster. In addition, these patterns also differed from the ChE activity in the mouse incisor. These results strongly suggest that ChE may play roles in the differentiation of the dental epithelium and dental follicle in hamster, and that morphogenetic subtypes of ChE may be variable among species and tooth types.

Expression of Frizzled Protein in Mouse Tooth Germ at Bell Stage / 中国医科大学学报

Objective To observe the expression of Frizzled protein in mouse tooth germ at bell stage and explore the possible function of Wnt/Frizzled signal molecules. Methods Mouse embryos at 17 and 19 days of gestation (E17 and E19) as well as mice postnatal day 2 (PN2) were employed in our study. The frozen sections of the first lower molar were made and indirect immunofluorescence technique was carried out on the sections. The location of Frizzled protein was observed under the fluorescence microscope. Results Frizzled protein was expressed weakly in the inner- and outer- dental epithelium at E17. At E19,the positive staining was found to distribute at the summit of both pre-ameloblasts and pre-odontoblasts. At P2,Frizzled protein was expressed strongly at the summit of ameloblasts and odontoblasts. Conclusion Wnt/Frizzled signal molecules may be involved in the differentiation of ameloblasts and odontoblasts.

Garré's Osteomyelitis of the Mandible Caused by an Infected Wisdom Tooth / Oral Science International

Garré's osteomyelitis is generally considered to be synonymous with chronic osteomyelitis with proliferative periostitis and occurs most commonly in the first molar region of the mandible. We report a case of Garré's osteomyelitis caused by the infected tooth-germ of a wisdom tooth. A 12-year-old boy had a swelling of the right cheek and his right mandibular second molar was covered by gingiva with pus retention. X-ray examination showed a radiolucent area around the impacted tooth-germ of the wisdom tooth and extracortical new bone at the angle of the mandible. After preoperative treatment with antibiotics, the tooth-germ and extracortical bone were removed. The antibiotics treatment was continued for 18 days postoperation. No recurrence of pain or swelling has been observed thereafter.

Specific expression of nucleolin in cap-stage tooth germ of mouse / 上海第二医科大学学报

Objective To investigate the specific expression of nucleolin in the development of cap-stage tooth germ of mouse embryo,and detect the possible biological function of nucleolin. Methods In situ hybridization and immunohistochemistry were performed to detect the expression of nucleolin mRNA and protein in the development of tooth germ at embryo day 15(E15).Double staining for apoptotic cells and nucleolin was employed to explore the relationship between nucleoin and apoptosis in tooth germ. Results The expression of nucleolin mRNA and protein was mainly detected in the cervical loop,inner epithelium and the underlying dental papilla.Moreover,nucleolin protein was also located in the primary enamel knot and basement membrane.It was revealed by double staining that the fluorescence images of nucleolin and the location of apoptotic cells were not overlapped. Conclusion The expression pattern of nucleolin mRNA do not completely coincide with that of nucleolin protein at the cap stage of tooth germ.The location for nucleolin protein in the basement membrane suggests that nucleolin may be involved in the reciprocal interactions between the inner epithelium and dental papilla mesenchyme,subsequently affect the morphogenesis of tooth germ.

Immunohistochemical localization of enamelin in developing rat tooth germ / 北京大学学报(医学版)

Objective: To observe the immunohistochemical localization of enamelin in enamel formationand mineralization. Methods: Tissue sections of the first mandibular molar tooth germ from 1, 3, 7, 10, 14 days rats after birth were prepared, expression of the enamelin protein was identified by immunohistochemical technique. Results: Enamelin was found in the cytoplasm of ameloblasts in 1-10 days old rat postnatal first mandibular molar tooth germs. Enamelin appeared weakly in the tooth germs of 1 day rats. From 3 to 10 days, enamelin localized both in the cytoplasm of ameloblasts and the uncalcified enamel from the dentino-enamel junction to surfaces of the tooth. Enamelin protein was negative in the tooth germs of 14 days rats postnatally. Conclusion: Enamelin protein is synthesised and secreted by ameloblasts, specially localized in enamel from DEJ to surfaces of the tooth, suggesting that enamelin has important roles in enamel formation.