FGF2对体外培养牙胚冠部形态的调控作用

目的：观察FGF2对体外培养的小鼠第一磨牙牙胚冠部形态分化发育的影响。方法：取18d胎龄的鼠胎下颌第一磨牙牙胚，置于含外源性FGF2的半固态培养基表面，组织学观察FGF2对体外培养的牙胚发育的影响。结果：经10μg/ml FGF2作用的磨牙胚培养9d后形成高耸的牙乳头尖，牙胚体积增大，牙尖及邻近部位牙乳头细胞分化为柱状或高柱状的成牙本质细胞，排列整齐，并有基质开始沉积，细胞分化程度、数量均高于对照组。结论：FGF2具有诱导牙胚组织细胞分化的功能。     

Methylphenidate effects on mice odontogenesis and connections with human odontogenesis

Odontology - The purpose of this study is to evaluate the effects of Methylphenidate exposure on mice odontogenesis and connect them by bioinformatics with human odontogenesis. Thirty-two pregnant...     

Comparative effects of parathyroid hormone on osteoblasts and cementoblasts

Although bone, dentin and dental cementum are mesenchymal mineralized tissues composed mainly of collagen and hydroxy apatite, they differ markedly in their suceptibility to resorption. Bone undergoes physiological resorption to which the dental tissues appear to be resistant. Recently, the cells covering bone surfaces have been attributed a regulatory role in osteoclastic bone resorption by exposing the bone surface following stimulation with hormones and inflammatory mediators, thereby allowing osteoclasts to colonize the bone surface. In the present study, it was shown that reparative cementum-forming cells covering an experimental cavity in the root surface of replanted monkey incisors were unaffected by parathyroid hormone, a potent mediator of bone resorption. In parallel experiments, endocranial osteoblasts exposed bone surface by widening their inercellular spaces. It was concluded that the layer of cells covering the root surface forms a protective barrier against resorption which serves to preserve the integrity of the dental root.     

降钙素对人骨巨细胞瘤组织中破骨细胞的影响

目的观察降钙素对人骨巨细胞瘤(giant cell tumor of bone,GCT)组织中纯化的破骨细胞的数量以及细胞核因子-κB受体活化因子配基(RANKL)蛋白表达的影响。方法利用破骨细胞贴壁快以及耐胰蛋白酶的特性,采用0.25%胰蛋白酶和0.2%I型胶原酶来分离纯化骨巨细胞瘤中的破骨细胞,设立对照组和试验组,在实验组培养液中加入浓度为10-8mol/L的降钙素,以抗酒石酸酸性磷酸酶(TRAP)染色观察破骨细胞数目、形态,用免疫组化方法观察RANKL的表达。结果从骨巨细胞瘤中纯化方法得到的破骨细胞数量较多,加药组破骨细胞数目较对照组明显减少(P<0.05)。RANKL的蛋白表达两组未见明显差异(P>0.05)。结论降钙素可显著的抑制骨巨细胞瘤中纯化破骨细胞的分化和功能。     

In vitro synchronization of embryonic mouse incisor preodontoblasts and preameloblasts: repercussions on terminal differentiation

Preodontoblasts divide asynchronously and their terminal differentiation occurs gradually. Experimental data suggested that the expression of competence by preodontoblasts to respond to specific epigenetic signals, triggering their overt differentiation, requires a minimal number of cell cycles. The intrinsic timing mechanism could imply division counting and preodontoblasts of juxtaposed cell generations might sequentially withdraw from the last physiological cycle. To test such an hypothesis, embryonic mouse lower incisors were cultured in vitro and treated sequentially with nocodazole in order to induce a transitory synchronization of the dividing preodontoblasts and preameloblasts. This synchronization led to a disorganization of the physiological gradual terminal differentiation of the odontoblasts, giving rise to three distinct domains comprising respectively: 1) odontoblasts with altered polarization and predentin secretion; 2) odontoblasts demonstrating equivalent polarization and predentin deposition; and 3) preodontoblasts-odontoblasts involved in gradual terminal differentiation. These results strongly suggest that the gradient of odontoblast functional differentiation results from sequential withdrawal from asynchronous cell cycles of competent cells able to overtly differentiate.     

In vitro effect of sodium fluoride on antioxidative enzymes and apoptosis during murine odontogenesis

J Oral Pathol Med (2010) 39 : 709–714 Excessive fluoride ingestion has been identified as a risk factor for fluorosis and oxidative stress. The oxidative stress results from the loss of equilibrium between oxidative and antioxidative mechanisms that can produce kinase activation, mitochondrial disturbance and DNA fragmentation, resulting in apoptosis. Actually many people are exposed to no‐adverted fluoride consumption in acute or chronic way. The aim of this study was to determine the effect of sodium fluoride on first molar germ in relation to its effect on antioxidative enzymes immunoexpression and apoptosis. Thirty first molar germs from 1‐day‐old Balb/c mice were cultured for 24 h with sodium fluoride (0 mM, 1 mM and 5 mM). Immunoexpression determination of CuZnSod, MnSod, catalase, Bax, Bid, caspase 8, caspase 9, caspase 3 and TUNEL assay were perfomed. Cellular disorganization in ameloblast and odontoblast‐papilla zones was observed. CuZnSod and MnSod immunoexpression decrease in experimental groups. Caspase 8, caspase 3, Bax, Bid increase expression and more TUNEL positive cells in both experimental groups than control, suggest that apoptosis induced by fluoride is related to oxidative stress due to reduction of the enzymatic antioxidant.     

Effects of Diazo-oxo-norleucine on cell kinetics and odontoblast differentiation in cultured embryonic mouse molars

Diazo-oxo-noreleucine (DON), an analogue of glutamine, prevented odontoblast differentiation in cultured tooth germs. Diazo-oxo-norleucine added after the onset of odontoblast differentiation, did not affect the secretion of predentine or the functional differentiation of ameloblasts. DON decreased expiant volume and modified cell kinetics, decreasing mitotic index, labelling index and number of grains per nucleus; the S phase of the cell cycle was lengthened. These modifications of cell kinetics should be considered when interpreting the effects of DON on odontoblast differentiation.     

In vitro development of lower first molars from the osteopetrotic microphthalmic (mi) mouse

While the precise mechanism of tooth eruption remains unknown it has been established that for tooth eruption to occur a functioning dental follicle is essential and normal bone resorption is required. In the osteopetrotic microphthalmic (mi) mouse, teeth fail to erupt and development is affected. In the present study, an organ culture technique was established to culture successfully lower first molars from normal and affected mi mice so as to determine if developmental defects were intrinsic to the dental tissue or whether such defects were a result of local environmental factors. Tissue was cultured for up to 13 days and development assessed morphologically at varying time intervals using standard light microscopy. Teeth developed similarly in both animal groups studied. The only variation in the appearance of cultured tissue occurred in the cervical loop region with more curling evident in dental tissue from the affected animals. The results of this study therefore showed that dental tissue from both normal and affected mi mice can be cultured for up to 13 days and that there is no difference in their development. It would appear that these teeth have the same ability to develop and consequently erupt, however the local environment influences tooth development and alters the eruption potential.     

生长激素对牙和颅颌面结构发育的影响

生长激素是个体出生后生长发育的重要调节物质,能促进体内肌肉、骨骼和软骨等多种组织内细胞的增生和分化。即生长激素能调节与牙形成相关的上皮-间充质相互作用,调节成釉细胞、成牙本质细胞和成牙骨质细胞分化成熟,影响牙体硬组织结构的形成;参与调节破骨细胞骨吸收过程,影响牙萌出;通过胰岛素样生长因子-1调节髁突软骨细胞的生长分化,影响颞下颌关节的发育;直接或间接影响膜内成骨和软骨成骨,进而调节颌骨的发育,影响面部结构。     

Qualitative effects of dioxin on molars vary among inbred mouse strains

OBJECTIVE: We evaluated the effects of different levels of the potent environmental toxicant and teratogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on molar development in mice in six inbred strains, all with TCDD responsive Ahr alleles. DESIGN: Pregnant females were exposed on gestation day 13 to 4 different levels of TCDD (control, 0.01, 0.1 and 1.0 microg/kg) and their offspring were examined for the frequency of missing third molars (M3s) and for differences in first mandibular molar (M1) cuspal morphology. RESULTS: Missing M3s were prevalent only in mice in two strains, C3H/HeJ and CBA/J, and their frequency significantly increased with increasing TCDD exposure. The frequency of the M1 variant was high in mice in only one strain, C57BL/10J, and was significantly higher in the treated compared with the control group. CONCLUSIONS: Inbred mice strains exhibited differential responses to TCDD suggesting that there is a genetic component, beyond Ahr differences, mediating the effects of TCDD on molar development.     

牙本质涎磷蛋白反义核酸对体外培养牙胚发育、矿化的影响

目的：探讨牙本质涎磷蛋白(dentin sialophosphoprotein，DSPP)在牙胚发育及矿化中的作用。方法：胎龄为17dBalb／c胎鼠上颌第一磨牙，对照牙胚置于无血清BGjb半固定培养基中培养；其余牙胚分别置于含有30μmol／L长15bp的DSPP反义或正义寡核苷酸的BGjb半固体培养基中培养。牙胚体外培养16d后，分别进行HE和von Kossa检测。结果：体外培养16d后，对照组和正义组牙胚生长良好，大小和形态相似。von Kossa染色显示沿牙本质基质走向有明显的矿化线；而反义组牙胚体积明显小于对照组，且在根方上皮根鞘转折处，上皮细胞分化程度低于对照组。von Kossa染色为阴性。结论：本研究用直接的实验结果说明DSPP反义核酸可以影响牙胚的生长，抑制牙胚的矿化。研究证实：DSPP在牙齿矿化中起着重要作用。同时，研究结果还提示：DSPP在维持牙齿的正常生长中也起着重要的作用。     

The effects of local hypothermia on odontogenesis.

Cryosurgery, with temperatures ranging from -40 C to -140 C, was performed on 32 developing mandibular third and fourth premolar buds of dogs. Evaluations were made on clinical, radiographic, and histologic bases at prescribed time intervals. There was complete inhibition of odontogenesis in 62.5% of third premolars and 25% of fourth premolars. There was 25% partial inhibition of third premolars and a 56.25% inhibition of fourth premolars. The adjacent developing tooth buds and bone were not affected.     

Ultrastructure of the effects of calcitonin on the development of mouse tooth germs in vitro

Mandibular first molars, from 17-day-old embryos, were cultivated in control medium or medium containing 0.1, 0.01 or 0.001 unit/ml of calcitonin (CT) for periods up to 10 days. In untreated tooth germs, cells of the dental papilla differentiated into pre-odontoblasts up to 4 days and predentine was seen on day 6. Cells treated with 0.1 unit/ml of CT differentiated into pre-odontoblasts up to 4 days, but no predentine was formed even after 10 days in culture. With 0.01 unit/ml, cells differentiated into odontoblasts, and had already secreted predentine a few days earlier than the untreated group. With 0.001 unit/ml, the developing germs were similar to the control expiants during the entire 10-day cultivation period. The proportional area of rough endoplasmic reticulum to cytoplasm of the odontoblasts was low at 0.1 unit/ml of CT and high at 0.01 unit/ml compared to the untreated expiants.     

甲状旁腺激素对体外培养的大鼠牙胚分化的影响

目的：观察甲状腺旁腺激素（ｐａｒａｔｈｙｒｏｉｄ ｈｏｒｍｏｎｅ,ＰＴＨ）对体外培养１７ｄ的胎鼠下凳第一磨牙牙胚分化发育的影响,探讨ＰＴＨ在成牙本质细胞分化和牙本质形成中的作用。方法：器官培养、组织学观察和透射电本外培养的牙可出现顾牙本质细胞分化和牙本质形成。ＰＴ可促进成牙本质细胞的分化,能活跃状态。结论：牙胚培养在观察生长因子对牙齿发育的作用研究是有效的,ＰＴＨ在牙齿发育中具有一定的促进作用。     

The effects of cyclophosphamide on odontogenesis in the rat

Twelve Wistar rats weighing 250–400 g were divided into four groups. Three groups were given respectively 40, 80 and 120 mg cyclophosphamide per kg by single intraperitoneal injections. The fourth, control, group was given 2 cm³ normal saline. One animal from each group was killed after 1, 4 and 8 days. After 1 day, the cytotoxic and cytolytic effects of the drug in the basal area of the mandibular incisors was most notable in the undifferentiated mesenchymal cells in the proliferating zone of the tooth pulp in all experimental groups. Injury to some cells of the enamel organ was apparent in 80 mg/kg and 120 mg/kg groups. Ameloblasts and odontoblasts appeared to be unaffected. After 4 days, all experimental groups showed cessation of root growth and relative acellularity of the basal part of the pulp. The sheath of Hertwig was continuous and the cells of the basal odontogenic epithelium appeared viable. On the 8th day, the basal odontogenic tissues appeared normal in 40 mg/kg and 80 mg/kg groups, and basal odontogenesis had recommenced in the 40 mg/kg group. The basal area of the pulp was acellular in the 120 mg/kg group. The control group showed no abnormality. The results suggest that in the incisor of the rat the undifferentiated mesenchymal cells in the proliferating zone of the tooth pulp are most notably affected by cyclophosphamide. The extent of injury and severity of the disruption in odontogenesis appear to be related to the dose of the drug.     

In vitro evaluation of the marginal seal of four restoration materials on deciduous molars

The aim of this study was to compare the marginal microleakage of Fuji II LC (A), composite resin Z250 (B), Fuji IX GP (C), and Dyract AP (F) in class V cavities and at the Fuji II LC/Z250 (D) and Fuji IX GP/composite resin Z250 (E) interfaces of an open sandwich technique on deciduous teeth. After thermocycling the mean marginal dye penetration at the enamel junction was 21.6 microns +/- 14.2 for group A; 83.6 microns +/- 32.3 for group B; 7.5 microns +/- 7.5 for group C; 38.7 microns +/- 27.5 for group D, and 0 micron for groups E and F. Mean dye penetration at the cementum junction was 37.1 +/- 20.2 (A); 123 +/- 42.1 (B); 28.7 +/- 17.1 (C); 0 (D); 14.4 +/- 14.4 (E); and 0 (F) microns. No leakage was seen at the junction between Fuji II LC and Z250 (0 micron), whereas a mean leakage of 184 microns between Fuji IX and Z250 was measured. In enamel the best seal was obtained with Dyract AP, but with differences at the limit of significance (P = 0.07). Sealing was significantly worse with Z250 (p = 0.03 versus Fuji II LC; p = 0.006 versus Fuji IX GP; and p = 0.003 versus Dyract AP). In cementum, the comparison between the grouped data Z250-Fuji II LC versus Fuji IX GP-Dyract AP was highly significant (p < 0.001), while there was no detectable difference between Z250 and Fuji II LC.