Immunohistochemical expression of heat shock protein27 in the mouse dental pulp after immediate teeth separation.

AIM: After immediate teeth separation, expression of HSP27 in the mouse dental pulp was examined. Immunohistochemistry was performed to examine the incidence of HSP27 expression. MATERIALS AND METHODS: A total of 36 8-week-old ddY mice were used as experimental subjects and a wedge was inserted in between maxillary right molars. The wedge was removed 30 min or 3 h after insertion. Animals were immediately sacrificed after the removal of wedge or until 1 week later and serial sections from paraffin-embedded tissues were prepared. Immunohistochemistry was carried out to examine the expression of HSP27. The untreated side served as the control. RESULTS: In the control group, the endothelial cells and some pulp fibroblasts weakly expressed HSP27 suggesting that the expression is due to mechanical stress brought about by physiological masticatory force and pressure from the tongue. In both 30 min and 3 h experimental groups, HSP27 expression was highest at 24 h after wedge removal and the expression remained the same or started to decrease thereafter. The expression decreased at the same level as that of the control group 1 week after wedge removal. CONCLUSION: HSP27 may serve as an indicator of stimulus strong enough to show its expression.

Immunohistochemical expression of hard tissue related factors in the mouse dental pulp after immediate teeth separation.

We examined change of Runx2 and ALP expression in mouse tooth pulp which exposed to teeth separation experiment by immunohistochemistry as a model for conservative dentistry treatment. 8-week-old 36 male ddY mice were used and wedge was inserted between upper 1st and 2nd molars. The wedge was removed 30 minutes as well as 3 hours after the insertion and the samples were prepared extending up to 1 week of time period for regular histopathological and immunohistochemical examinations for ALP and Runx2 expression. The opposite sides without wedge insertion were taken as controls. In the control group pulp, weak expressions of Runx2 and ALP in the vessel endothelial cells as well as the pulp cells were revealed, suggesting the appearance of these genes upon mechanical stress induced by mastication and tongue pressure etc. On the other hand in the experiment group, Runx2 expression increased both in 30-minute and 3-hour teeth separation group. The expression became maximum at 24 hours. Then it gradually decreased and became similar level with the control group at 1-week after the wedge insertion. Similarly ALP expression increased after the wedge insertion and was maximum at 24 hours and then gradually decreased to the levels similar with the control group. These results suggest that when immunohistochemical expression of Runx2 as well as ALP was used as an index, no severe damage occur upon clinical application of wedge insertion.

Role of Msx2 as a promoting factor for Runx2 at the periodontal tension sides elicited by mechanical stress.

Early changes of Runx2 and Msx2 expressions were examined by immunohistochemistry in mouse periodontal ligament exposed to mechanical stress. 8-week-old ddY mouse was used as experimental animal. To provide a continuous mechanical stress on periodontal ligament, rubber dam sheet was placed between upper molars of the mouse. At 20 minutes, 1 hour, 3 hours, 9 hours and 24 hours after insertion of the sheet, relevant parts of the mouse tissues were excised and fixed in 4% paraformaldehyde/0.05M phosphate buffered fixative solution. Then serial paraffin sections were prepared and histopathological evaluation as well as examination of Runx2, Msx2 and alkaline phosphatase (ALP) expressions by immunohistochemistry were performed. Control animals were not subjected to mechanical stress. In the experimental group, strong expressions of Runx2 and Msx2 were seen in periodontal fibroblasts of the tension side at 20 minutes after mechanical stress. Expressions of Runx2 and Msx2 became stronger in parallel with time, and at 24 hours after mechanical stress, the periodontal fibroblasts, cementoblasts as well as osteoblasts showed strong expression. Moreover, ALP has also demonstrated similar strong expression. On the other hand, in the control group, although expressions of Runx2, Msx2 and ALP were detected at all the experiment times, the expressions were weak. All these results strongly suggested that Runx2 promoted differentiation of osteoblasts at early stage and Msx2 worked as an activator of Runx2 function.

Gene expression of Jagged2 in mandibular condylar cartilage development.

Expression pattern of Jagged2 gene in mandibular condylar cartilage was examined by means of in situ hybridization (ISH) technique. At E14, Jagged2 mRNA signals appeared in cytoplasm of proliferating chondrocytes. From E15 to E19, Jagged2 mRNA was detected throughout almost all cytoplasm in all layers. However, the distribution pattern was not uniform. These results suggest that Jagged2 plays an essential role for mandibular condylar cartilage morphogenesis and development.

Notch signaling in mandibular condylar cartilage development.

OBJECTIVE: The purpose of this study was to investigate the expression pattern of Notch signaling in mandibular condylar cartilage, as a type of secondary cartilage. METHODS: Mandibular condyle of ddY mice were fixed from embryonic day 14 (E14) through just after birth (equivalent to E19). Samples were cut into 4 mum serial sections through the central area of the mandibular condyle at the sagittal plane. Serial sections were examined using histological, immunohistochemical (IHC) and in situ hybridization (ISH) techniques. RESULTS: At E14, there were no developmental features of mandibular condyle. At the distal upper portion of developmental mandibular bone, mesenchymal cell proliferation and condensation without metacholomatic reaction to toluidine blue (TB) were seen. At E15, mandibular condylar cartilage was clearly evident, as TB metacholomasia. In IHC specimens at E14, expression of Notch1 intracellular domain (NICD) was observed in the nuclei of coagulating mesenchymal cells. After E15, NICD appeared in the nuclei and the cytoplasms of cells. In ISH examination at E14, expressions of Notch1 mRNA appeared in cytoplasm of proliferating chondrocytes. From E15 to E19, Notch1 mRNA was detected throughout almost all cytoplasm in all layers. CONCLUSION: These IHC and ISH results suggest that Notch signaling plays an essential role for mandibular condylar cartilage morphogenesis and development.

Three-dimensional observation of reconstruction course of rabbit experimental mandibular defect with rhBMP-2 and atelocollagen gel.

For the experimental animals, eight rabbits were chosen. A bone defect was made and was filled with 1% atelocollagen gel including rhBMP-2 10 microg. The reconstruction course was observed using micro-computed tomography (muCT) in vivo. In muCT observation, the density was slightly elevated at the bone marrow side at day 7, and the phenomenon gradually expanded during the course of this experiment which lasted for 28 days. By utilized muCT, we could construct 3D images, and that process enabled us to visualize bone formation more closely. These data suggest that the experimental animal model muCT and 3D image are extremely useful for follow-up of reconstruction of animal bone defects and that the atelocollagen gel is effective as a carrier of rhBMP-2.

Bone repair of rabbit mandibular transsection using rhBMP-2 and atelocollagen gel.

This experimental was carried out using 12 rabbits. A rabbit experimental mandibular transsection was reconstructed with 10mug of rhBMP-2 and 1% atelocollagen gel. The transsection gap was fixed with a titanium plate and screws, and covered with poly (lactic-co-glycolic acid) co-polymer (PLGA) membrane. Histopathological examination of 1-week specimens revealed that many spindle cells had proliferated and invaded blood clots, and a small amount of immature trabecular bone was formed in the transsection gap. In 2 and 3-week specimens, bone formation was gradually increased in the fibro-vascular tissues of the site. These histological findings were also observed in the control group specimens, but the bone formation was slightly less than in the experimental group. The results suggest the effectiveness of atelocollagen gel as a carrier of rhBMP-2 and PLGA as a covering membrane in this rabbit mandibular transsection reconstruction model.

Expression of Notch in a case of osteosarcoma of the maxilla.

In this immunohistochemical examination, the expression of Notch1 peptide was detected in neoplastic cells in a case of osteosarcoma of the maxilla of a 31-year-old Indonesian male patient. Notch1 peptide appeared in the cytoplasm of neoplastic cells of comparatively well-differentiated areas of the osteosarcoma, an osteoblastic area containing osteoid and/or immature bone tissues. The results suggest that Notch1 is closely related to cytological differentiation or acquisition of cytological characteristics in neoplastic cells of osteosarcoma.

Relationship of the hyoid bone and posterior surface of the tongue in prognathism and micrognathia.

In order to study relationship of the hyoid bone and posterior surface of the tongue in prognathism and micrognathia, we focused on the effect of the tongue on the upper airway lumen in 16 patients with Angle's Class II and 51 patients with Angle's Class III, and assessed the position of the hyoid, the depth from the posterior surface of the tongue, from the bottom of the vallecula and from hyoid bone to the posterior pharyngeal wall using lateral cephalograms. We were able to assess significant correlations between the posterior surface of the tongue and hyoid position in Angle's Class III. However, we found no association between them in Angle's Class II. This could be an adaptive feature of the genioglossus in response to hyoid localization to serve a compensatory role to prevent respiratory impairment in micrognathia at risk of apnoea.

Alteration of the angle of the coronoid process in prognathism.

Muscles and bones may dynamically affect the functions of each other, resulting in changes in the activity of the muscle and/or morphological change in the bones. However, alterations of the morphology of the coronoid process have not been documented in relation to the temporal muscle between the mandible and the cranium. Angles of the coronoid process to the line through the right and the left frontotemporale were measured on posteroanterior (PA) cephalograms in patients with normal occlusions and Class II, division 1 malocclusions, and those with true skeletal Class III malocclusions. Standard deviation of the angle of the coronoid process in patients with Class III malocclusions was greater than those subjects with normal occlusion or Class II, division 1 malocclusions. Differences of angles between the right and the left coronoid process in each patient of either sex were significantly large in true skeletal Class III malocclusions (both P < 0.001). Large variation of angle of the coronoid process was related to prognathism, and this effect may represent adaptation of temporal muscle function to a variety of alterations in mandibular morphology.

Odontoclastic resorption of the superficial nonmineralized layer of predentine in the shedding of human deciduous teeth.

Resorption by odontoclasts of a superficial nonmineralized layer of predentine that occurs in prior to the shedding of human deciduous teeth was studied by light and electron microscopy. As resorption of the tooth roots neared completion, multinucleate cells appeared on the predentine surface of the coronal dentine between the degenerated odontoblasts, excavated characteristic resorption lacunae in the nonmineralized predentine. These multinucleate cells had the same ultrastructural characteristics as odontoclasts and histochemical demonstration of tartrate-resistant acid phosphatase activity in the multinucleate cells revealed intense staining in numerous small granules identified as lysosomes. Occasionally, the multinucleate cells simultaneously resorbed both nonmineralized and calcospherite-mineralized matrix in the predentine. The study demonstrates that multinucleate odontoclasts can resorb nonmineralized predentine matrix in vivo, probably in the same way as they resorb demineralized organic matrix in the resorption zone underlying their ruffled border.

A histological study of the exfoliation of human deciduous teeth.

For clarification of the histological details of the shedding of human deciduous teeth, exfoliated and extracted deciduous teeth were examined by light and electron microscopy. After the roots were completely resorbed, the dentogingival junction migrated along the inner resorbing surface and finally reached the pulpal surface of the crown. At the same time, the gingival epithelium also proliferated and migrated under the crown of the deciduous tooth in such a way that part of it lined the residue of the pulp and another part lined the surface overlying the erupting successional tooth. This phenomenon took place from various sides of the tooth surface. Therefore, just before exfoliation, the migrated gingival epithelium formed narrow necks of tissue, and the crown was only superficially attached to the gingiva by them. The final shedding of the tooth appeared to occur by a tearing of these narrow tissue regions. The results of the present study suggest that the dento-gingival junction as well as gingival epithelium play important roles in the process of exfoliation of human deciduous teeth.

Cementum-like tissue deposition on the resorbed pulp chamber wall of human deciduous teeth prior to shedding.

In the later stage of exfoliation in human deciduous teeth, odontoclastic resorption takes place at the pulpal surface of the coronal dentin. However, this resorption does not continue until the teeth are shed, and the resorbed pulp chamber wall is usually repaired by cementum-like tissue deposition. In this study, we examined the formation and characteristics of the cementum-like hard tissue on the resorbed dentin surface in the pulp chamber of deciduous teeth prior to shedding. The site and degree of deposition of newly formed cementum-like tissue on the resorbed pulp chamber wall varied from tooth to tooth. Furthermore, they also showed compositional and structural variations. Generally, however, the matrix of the cementum-like tissue was composed of intrinsic collagen fibers, acellular or cellular. There was a tendency for acellular cementum-like tissue to be deposited on small and shallow resorption bays, whereas the cellular type was found on larger and deeper ones. In both cases, the surface of the deposited cementum-like tissue on the resorbed dentin surface usually became flat. However, unlike the cementum repair of resorbed areas on the root surface, no acellular extrinsic fiber cementum-like tissue was found on the resorption pulp chamber wall. Although the role of the repair of the resorbed pulp chamber wall with cementum-like tissue deposition just before shedding is unknown, it might play some role in the retention of deciduous teeth until shedding.

Odontoclastic resorption at the pulpal surface of coronal dentin prior to the shedding of human deciduous teeth.

Histological and histochemical observations of more than 150 extracted human deciduous teeth revealed that, prior to shedding, odontoclastic resorption as a rule takes place at the pulpal surface of coronal dentin. We also found that this phenomenon occurs in all kinds of deciduous teeth. The process of this internal resorption of coronal dentin of deciduous teeth clearly showed time-related histological changes. During the time the roots were actively being resorbed, the pulpal tissue retained its normal structure. However, when root resorption neared completion, inflammatory cells started to gradually infiltrate into the pulp, and odontoblasts began to degenerate. After that, multinucleate odontoclasts appeared, and resorption proceeded from the predentin to the dentin. The odontoclastic activity was initially detected only on the pulpal surface at the bottom areas of the crown. It gradually spread towards the pulpal horn regions along the wall of the pulp chamber. However, this internal resorption of coronal dentin did not continue until the teeth were finally shed. After the elimination of resorption, the resorbed dentin surface was repaired by a cementum-like deposition or covered with fibrous connective tissue.

[A disposable tracheal spray device for patients in whom it is difficult to indwell a urinary catheter].

A disposable tracheal spray device was utilized for 20 patients in whom it was difficult to indwell a urinary catheter in the past 4 years. Among them, 18 patients were successfully inserted with a Foley catheter after sufficient lubrication of whole urinary tract with lidocaine using this device. In one patient for gastrectomy, it was not possible to insert because of obstruction of the urinary tract at the prostate. Another patient showed abnormal urinary tract with normal urination. There were no major complications by this manipulation. It was concluded that this application could provide useful informations about the urinary tract in the patients with difficulty for insertion of the urinary catheter, and it provides sufficient lubrication for the indwelling.