Differentiation of odontogenic tissues in organ culture

abstract – Molar tooth germs from 17-d-old mouse embryos were cultivated in a Trowelltype culture, and different culture media were tested for their ability to support enamel formation. The medium which allowed secretion of considerable amounts of enamel matrix by ameloblasts consisted of BGJb medium supplemented with 20 % horse serum, 10 % chick embryo extract and 0.9 mM ascorbic acid. At the onset of culture the teeth were in the early bell stage. After 2 weeks of cultivation both odontoblasts and ameloblasts had differentiated, and considerable amounts of predentin and enamel matrix had been secreted. Similar development was also seen in teeth which had been enzymatically separated into the mesenchymal dental papilla and epithelial enamel organ and subsequently recombined in vitro . This method allows good differentiation of odontogenic tissues, and is considered suitable for further studies of tissue interactions in the tooth rudiment.     

Differentiation of odontogenic tissues in organ culture.

Molar tooth germs from 17-d-old mouse embryos were cultivated in a Trowell-type culture, and different culture media were tested for their ability to support enamel formation. The medium which allowed secretion of considerable amounts of enamel matrix by ameloblasts consisted of BGJb medium supplemented with 20% horse serum, 10% chick embryo extract and 0.9 mM ascorbic acid. At the onset of culture the teeth were in the early bell stage. After 2 weeks of cultivation both odontoblasts and ameloblasts had differentiated, and considerable amounts of predentin and enamel matrix had been secreted. Similar development was also seen in teeth which had been enzymatically separated into the mesenchymal dental papilla and epithelial enamal organ and subsequently recombined in vitro. This method allows good differentiation of odontogenic tissues, and is considered suitable for further studies of tissue interactions in the tooth rudiment.     

石蜡包埋口腔白斑组织检测目的基因的方法探讨

目的探索在石蜡包埋的口腔白斑组织中高效、快捷地检测目的基因的方法。方法采用25例10％福尔马林固定、石蜡包埋的口腔白斑组织，比较显微解剖-巢式PCR法、蛋白酶K消化-PCR法与传统酚氯仿抽提-PCR法3种方法，检测共济失调毛细血管扩张综合征突变基因（ataxia telangiectasis mutated，ATM）的扩增阳性率。结果3种方法PCR扩增率分别为84％、52％与64％，显微解剖-巢式PCR法与蛋白酶K消化-PCR法相比差异有统计学意义（P=0．032）。结论显微解剖．巢式PCR方法组织用量少，DNA检出率高且简便易行，是一种值得推荐的方法。     

Covert self-mutilation of oral tissues and skin by mechanical and chemical means

A case is presented in which a patient performed persistent covert acts of self-mutilation through mechanical and chemical means. The lesions first involved the oral mucosa and then the skin and were misinterpreted as erythema multiforme and pyoderma gangrenosum, respectively.     

Detection of human herpesvirus-8 DNA in oral ulcer tissues of HIV-infected individuals

OBJECTIVE: To determine the frequency of detection of human herpesvirus-8 (HHV-8) in HIV-related oral ulcers. DESIGN: Analysis of archived biopsy material. METHODS: Nested polymerase chain reaction of DNA extracts. RESULTS: HHV-8 DNA was detected in six of 10 oral ulcers of HIV-positive patients without oral Kaposi's sarcoma (KS) lesions and five of 11 oral KS lesions. The positive non-KS samples were derived from various oral sites. CONCLUSIONS: In HIV-positive people, HHV-8 can infect oral tissues that are not affected by KS.     

The effects of hypophysectomy upon DNA synthesis in rat oral epithelium.

Ten hypophysectomized and 10 normal female albino rats, 50-days-old, were kept for 5 days and treated with tritiated thymidine 1 hour before sacrifice of the animals. The animals were weighed and the histomorphology of the palate epithelium was studied including the thickness, cell density, and DNA labeling index. The hypophysectomized rats failed to gain weight after 5 days. The palatal epithelium showed a normal morphology indicating the hypophysectomy allowed for differentiation of squamous epithelium. There was a significant reduction in the thickness of the epithelium and a reduced cell density. This was attributed to a significant decrease in DNA synthesis. The epithelial cells were lost from the surface without adequate replacement due to an expected depression in mitotic activity. DNA synthesis may be depressed due to reduced ATP synthesis resulting from suboptimal glucose metabolism and depression in protein synthesis.     

Cytochemical demonstration of adenyl cyclase in rat incisor enamel organ

abstract — With adenylyl-imidodiphosphate as a specific substrate, adenyl cyclase has been demonstrated at the plasma membranes of all epithelial cells except the ameloblasts in the enamel organ of rat incisors. Hydrolysis of the substrate was found to be stimulated by 10 mM sodium fluoride in the incubation medium.     

金属栅栏式腭器官培养模型的建立

目的建立金属栅栏式小鼠腭器官培养模型。方法选取妊娠14 d的孕鼠20只,采用金属栅栏静式培养法,将腭器官分别培养24和48 h,肉眼以及苏木精-伊红染色观察腭器官在体外的发育过程。结果腭器官发育良好,细胞形态正常。腭器官培养24 h后可见到中脊上皮;培养48 h后可见中脊上皮消失,腭突融合。结论本方法为研究腭裂发病机制提供了一个良好的体外模型。     

Histological evaluation of surgically treated oral tissues after application of a photocuring periodontal dressing material

Abstract At present no information is available about biological effects on oral tissues of the photocuring periodontal dressing Barricaid®. This animal study examines histologically the tissue responses of surgical areas covered during 7 days with either Barricaid®. the eugenol-containing dressing Ward's Wondrpak® or the bionert control gel Carboxy Methyl Cellulose. One group was studied immediately after the removal of the dressings: in the other group, further healing was permitted for another week. Results after 7 days indicate acute inflammatory reactions in the test areas without significant differences between the 2 periodontal dressing materials. The control areas showed to a lesser degree basically the same tissue response. In the 2nd week, generally all areas healed. After 14 days, no differences between test- and control sites could be detected. From a biological point of view, these findings suggest no contra-indication for application of this photocuring dressing material after periodontal surgery.     

Study of serum CTX in 50 oral surgical patients treated with oral bisphosphonates

Objectives: To determine whether there is a relationship between the total BP dose administered and the variations in serum CTX concentration. Study design: The study included 50 patients requiring dental implant surgery and treated with oral BPs, seen in an Oral Surgery and Implantology Unit between January 2007 and June 2009. The patients were divided into two groups: those in which the medication was not suspended before obtaining the laboratory test sample, and those patients referred from other dental clinics in which BPs was suspended before reporting to our Unit. The total drug dosage administered and the total dose per kilogram body weight were evaluated for comparison with serum CTX. The data obtained were correlated to the osteonecrosis risk table developed by Marx et al. in 2007. Results: There were no significant differences between the two groups in relation to the total administered dose and the dose in mg/kg b.w. Likewise, in both groups no relationship was observed between the serum CTX value and the total administered dose or the dose in mg/kg b.w. No differences were found between the two patient groups regarding chemical osteonecrosis risk based on the criteria of Marx et al. Conclusions: No relationship was observed between the oral BP dose administered (total dose or expressed in mg/kg b.w.) and serum CTX concentration, and suspension of the medication did not influence the serum CTX levels. Key words:Serum CTX, osteonecrosis, oral bisphosphonates.     

A histological study of the short-term effects of fluoride on enamel and dentine formation in hamster tooth-germs in organ culture in vitro

First maxillary molars in early stages of secretory amelogenesis were exposed in vitro to fluoride (F-) concentrations ranging between 2.63 microM and 2.63 mM for up to 3 days. In contrast to the dentine papilla, which seemed unaffected by F- in concentrations up to 1.31 mM, the enamel organ was dose-dependently extremely sensitive for F-. Young ameloblasts which became secretory in vitro were in particular sensitive and did not secrete enamel adjacent to new, in vitro-formed dentine. Hypermineralization of the dentine at the enamel-dentine junction suggested that these ameloblasts still transport and deposit minerals. 52 microM was the lowest concentration of F- that inhibited deposition of enamel in the cervical-loop region. Ameloblasts, secretory at the time of exposure to F-, in concentrations of 52 microM up to 1.31 mM secreted an abnormal, amorphous, von-Kossa-negative enamel matrix. 1.31 mM of F- was the lowest concentration which induced the formation of a hypermineralized band in the pre-exposure enamel. 2.63 mM of F- was highly toxic for the enamel organ but had only moderate effects on the dentine papilla.     

改良组织块法体外原代培养口腔黏膜上皮细胞

目的 :探索一种新的、快捷、简单的人口腔黏膜上皮细胞体外原代培养方法 ,并建立稳定的人口腔黏膜上皮细胞体外培养体系。方法 :用DispaseⅡ分离上皮和皮下组织。采用改良的无血清及无 3T3 细胞的培养体系和改良组织块法原代培养口腔黏膜上皮细胞。比较改良组织块法和传统酶消化法原代培养上皮细胞的区别。结果 :用DispaseⅡ可成功分离上皮和皮下组织。改良组织块法可以显著简化原代培养实验步骤和缩短操作时间 ,并使原代上皮细胞更快达到传代要求。结论 :与酶消化法相比 ,改良组织块法是一种更好的上皮细胞原代培养方法。     

短期口服氟康唑胶囊治疗糜烂型口腔扁平苔藓的疗效观察

目的:探讨糜烂型口腔扁平苔藓(oral lichen planus,OLP)患者口腔真菌感染的患病情况,观察短期口服氟康唑胶囊治疗糜烂型OLP的临床疗效.方法:纳入糜烂型OLP患者60例,健康志愿者30例,通过口腔真菌涂片检查,比较两组真菌感染患病率.将60例糜烂型OLP患者随机分为实验组和对照组,分别接受口服氟康唑胶...     

Effects of areca nut, inflorescence piper betle extracts and arecoline on cytotoxicity, total and unscheduled DNA synthesis in cultured gingival keratinocytes

Betel quid (BQ) chewing has a strong correlation with oral leukoplakia, submucous fibrosis and oral cancer. For elucidation of its pathogenesis, we investigated the effects of areca nut (AN) and inflorescence piper betle (IPB) extracts and arecoline on the growth, total DNA synthesis (TDS) and unscheduled DNA synthesis (UDS) of cultured human gingival keratinocytes (GK). Arecoline and AN extract suppressed the growth of GK over 5 days of incubation in a dose-dependent fashion. At concentrations of 100, 200 and 400 μg/ml, AN extract suppressed the growth of GK by 31%, 46% and 90%, respectively. The IPB extracts exerted less inhibitory effect on the growth of GK. IPB extract (200–400 μg/ml) decreased cell numbers by 20–40% over 5 days of incubation. Moreover, at a concentration of 0.1, 0.2 and 0.4 mM, arecoline suppressed cell growth by 44%, 77% and 96%, respectively. However, only AN extract induced TDS and UDS in cultured GK within 6 h of exposure. Induction of UDS by AN extract was concomitant with the presence of apparent intracellular vaculoization. Arecoline was also toxic to GK, but did not induce intracellular vacuolization. At a concentration range of 200–1600 μ/ml, AN extract induced TDS by 2.1- to 6.5-fold. Furthermore, at a concentration of 400–1600 μ/ml, AN extract elevated the UDS by 2.4- to 5.5-fold more than that of untreated control. On the contrary, IPB extract (200–1600 μ/ml) and arecoline (0.2–1.6 mM) inhibited the TDS and UDS of GK to a different extent. Simultaneous exposure of confluent GK to AN extract, IPB extract and arecoline for 1 to 5 days led to different degrees of cytotoxicity that was dose-and time-dependent. These results indicate that AN, IPB and arecoline take part in the pathogenesis of BQ chewing-related oral mucosal lesions, possibly through both genotoxic and non-genotoxic mechanisms.