• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.199-206
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• 2010

This study investigated the effects of strontium on osteoblastic phenotypes of cultured human periostealderived cells. Periosteal tissues were harvested from mandible during surgical extraction of lower impacted third molar. Periosteal-derived cells were introduced into cell culture. After passage 3, the periostealderived cells were further cultured for 28 days in an osteogenic induction DMEM medium supplemented with fetal bovine serum, ascorbic acid 2-phosphate, dexamethasone and at a density of $3{\times}10^4$ cells/well in a 6-well plate. In this culture medium, strontium at different concentrations (1, 5, 10, and 100 ${\mu}g$/mL) was added. The medium was changed every 3 days during the incubation period. We examined the cellular proliferation, histochemical detection and biochemical measurements of alkaline phosphatase (ALP), the RT-PCR analysis for ALP and osteocalcin, and von Kossa staining and calcium contents in the periostealderived cells. Cell proliferation was not associated with the addition of strontium in periosteal-derived cells. The ALP activity in the periosteal-derived cells was higher in 5, 10, and 100 ${\mu}g$/ml strontium-treated cells than in untreated cells at day 14 of culture. Among the strontium-treated cells, the ALP activity was appreciably higher in 100 ${\mu}g$/ml strontium-treated cells than in 5 and 10 ${\mu}g$/ml strontium-treated cells. The levels of ALP and osteocalcin mRNA in the periosteal-derived cells was also higher in strontium-treated cells than in untreated cells at day 14 of culture. Their levels were increased in a dose-dependent manner. Von Kossa-positive mineralization nodules were strongly observed in the 1 ${\mu}g$/ml strontium-treated cells at day 21 and 28 of culture. The calcium content in the periosteal-derived cells was also higher in 1 ${\mu}g$/ml strontium-treated cells at day 28 of culture. These results suggest that low concentration of strontium stimulates the osteoblastic phenotypes of more differentiated periosteal-derived cells, whereas high concentration of strontium stimulates the osteoblastic phenotypes of less differentiated periosteal-derived cells. The effects of strontium on osteoblastic phenotypes of periosteal-derived cells appear to be associated with differentiation-extent.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.287-296
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• 2008

The purpose of this in vitro study was to compare the remineralization effect of commercially available anticariogenic products, exactly low level fluoride mouthrinse(500 ppm NaF), tooth cream with Casein phosphopeptide-amorphous calcium phosphate(CPP-ACP) and fluoride mouthrinse plus tooth cream on artificial caries lesion. Artificial caries lesion was induced at the buccal surface of permanent third molar and the specimens were then divided(16 specimens/group) into four group. Twice a day during 28 days specimens of each group were treated with a commercially anticariogenic product as follows and applied to the pH cycling system. Group 1: control group (No treatment) Group 2: Tooth $Mousse^{(R)}$ (GC Co. Japan) Group 3: $chikachika^{(R)}$ (Samil Co. Korea) Group 4: $chikachika^{(R)}$+Tooth Mousse$^{(R)}$ The long-term change of mineral loss(${\Delta}Q$) was evaluated by quantitative light-induced fluorescence (QLF) and the following results were obtained: 1. ${\Delta}Q$ of Group 1 was not noticed statistically significant during 28 days comparing that prior to treatment. There was a statistically significant increase in ${\Delta}Q$ of Group 2 and 3 since 14 days. So was in ${\Delta}Q$ of Group 4 since 7 days. 2. ${\Delta}Q$ was increased as follows: Group 1< Group 2, 3< Group 4. 3. Comparing with Group 1, Group 2 was a statistically significant increase since 7 days and Group 3 and 4 were since 3 days. Comparing Group 2 with 3, there was not noticed statistically significant during whole duration. Group 4 was significantly higher than Group 2 and 3 after 28 days. 4. All groups demonstrated a decrease in the rate of remineralization as time goes on.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.197-205
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• 2007

Angiogenesis is a essential part for bone formation and bone fracture healing. Vascular endothelial growth factor (VEGF), one of the most important molecules among many angiogenic factors, is a specific mitogen for vascular endothelial cells. VEGF-mediated angiogenesis is required for bone formation and repair. However, the effect of VEGF on osteoblastic cells during osteogenesis is still controversial. In recent days, substantial progress have been made toward developing tissue-engineered alternatives to autologous bone grafting for maxillofacial bony defects. Periosteum has received considerable interest as a better source of adult stem cells. Periosteum has the advantage of easy harvest and contains various cell types and progenitor cells that are able to differentiate into a several mesenchymal lineages, including bone. Several studies have reported the bone formation potential of periosteal cells, however, the correlation between VEGF signaling and cultured human periosteal cell-derived osteogenesis has not been fully investigated yet. The purpose of this study was to examine the correlation between VEGF signaling and cultured human periosteal-derived cells osteogenesis. Periosteal tissues of $5\;{\times}\;20\;mm$ were obtained from mandible during surgical extraction of lower impacted third molar from 3 patients. Periosteal-derived cells were introduced into the cell culture and were subcultured once they reached confluence. After passage 3, the periosteal-derived cells were further cultured for 42 days in an osteogenic inductive culture medium containing dexamethasone, ascorbic acid, and ${\beta}-glycerophosphate$. We evaluated the alkaline phosphatase (ALP) activity, the expression of Runx2 and VEGF, alizarin red S staining, and the quantification of osteocalcin and VEGF secretion in the periosteal-derived cells. The ALP activity increased rapidly up to day 14, followed by decrease in activity to day 35. Runx2 was expressed strongly at day 7, followed by decreased expression at day 14, and its expression was not observed thereafter. Both VEGF 165 and VEGF 121 were expressed strongly at day 35 and 42 of culture, particularly during the later stages of differentiation. Alizarin red S-positive nodules were first observed on day 14 and then increased in number during the entire culture period. Osteocalcin and VEGF were first detected in the culture medium on day 14, and their levels increased thereafter in a time-dependent manner. These results suggest that VEGF secretion from cultured human periosteal-derived cells increases along with mineralization process of the extracellular matrix. The level of VEGF secretion from periosteal-derived cells might depend on the extent of osteoblastic differentiation.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.595-603
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• 2005

Incomplete removal of bacteria contaminated dentin or enamel associated with caries is a potential problem in restorative dentistry Secondary or residual caries, pulpal inflammation and hypersensitivity may result from bacteria left after the initial preparation, especially if an adequate seal against microleakage is not obtained. A possible solution to eliminate residual bacteria left in a cavity preparation would be to treat the cavity with cavity disinfectant wash. But a potential problem with using a cavity disinfectant with dentin bonding agents could be their interference with the ability of the resin to bond to the tooth micromechanically. The purpose of this study was to evaluate the effect of 2% chlorhexidine containing cavity disinfectant ($Consepsis^{(R)}$) on shear bond strength and microleakage of dentin bonding agents, $Adper ^{TM}$ $Scotchbond^{TM}$ Multi-Purpose, $Adper^{TM}$ Single Bond and $Adper^{TM}\;Prompt^{TM}\; L-Pop^{TM}$ Sixty and sixty sound human third molar teeth, respectively, were used for shear bond strength and microleakage test. For experimental group, cavity disinfectant was applied before dentin bonding agents, and was not applied for the control group. The result from the this study can be summarized as follows ; 1. Use of 2% chlorhexidine containing cavity disinfectant($Consepsis^{(R)}$) does not significantly affect the shear bond strength of dentin bonding agents. 2. Use of 2% chlorhexidine containing cavity disinfectant($Consepsis^{(R)}$) does not significantly affect the microleakage of dentin bonding agents.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.37-46
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• 2007

The C-shaped canal system is an anatomical variation mostly seen in mandibular second molars, although it can also occur in maxillary and other mandibular molars. The main anatomical feature of C-shaped canals is the presence of fins or web connecting the individual root canals. The complexity of C-shaped canals prevents these canals from being cleaned, shaped, and obturated effectively during root canal therapy, and sometimes it leads to an iatrogenic perforation from the extravagant preparation. The purpose of this study was to provide further knowledge of the anatomical configuration and the minimal thickness of dentinal wall according to the level of the root. Thirty extracted mandibular second molars with fused roots and longitudinal grooves on lingual or buccal surface of the root were collected from a native Korean population. The photo images and radiographs from buccal, lingual, apical direction were taken. After access cavity was prepared, teeth were placed in 5.25% sodium hypochlorite solution for 2 hours to dissolve the organic tissue of the root surface and from the root canal system. After bench dried and all the teeth were embedded in a self-curing resin. Each block was sectioned using a microtome (Accutom-50, Struers, Denmark) at interval of 1 mm. The sectioned surface photograph was taken using a digital camera (Coolpix 995, Nikon, Japan) connected to the microscope. 197 images were evaluated for canal configurations and the minimal thickness of dentinal wall between canal and external wall using 'Root Thickness Gauge Program' designed with Visual Basic. The results were as follows : 1. At the orifice level of all teeth, the most frequent observed configuration was Melton's Type C I (73%), however the patterns were changed to type C II and C III when the sections were observed at the apical third. On the other hand, the type C III was observed at the orifice level of only 2 teeth but this type could be seen at apical region of the rest of the teeth. 2. The C-shaped canal showed continuous and semi-colon shape at the orifice level, but at the apical portion of the canal there was high possibility of having 2 or 3 canals 3. Lingual wall was thinner than buccal wall at coronal, middle, apical thirds of root but there was no statistical differences.

• Journal of dental hygiene science
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• v.4 no.3
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• pp.103-109
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• 2004

The present study prepared 72 test samples - 24 made of amalgam alloy, 24 of Verabond (Ni-Cr alloy) for crown and 24 of Talladium $^{TM}alloy$ for denture - according to the manufacturers' manuals and general method in consideration of the width of the mesial-distal dental crown of the lower $1^{st}$ molar and MOD cavity in clinics, put them in a 200 ml beaker containing 80 ml of artificial saliva, and measured their galvanic corrosion at distances of 0 mm, 7 mm and 40 mm after 7 days. Isolated metals in the electrolyte such as Cu, Ag, Ni, Cr, Sn, Zn and Hg were quantitatively analyzed with Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES, JY-50P, VG Elemental Co. France), and from the results were drawn conclusions as follows. First, Cu, Sn, Ag, Hg and Zn were highly advantageous when amalgam contacted gold alloy compared to Ni-Cr alloy for crown and Talladium alloy for denture. In addition, although gold alloy was finest in terms of oral tissue and biocompatibility, it was most disadvantageous when it was with amalgam. Second, when amalgam contacted gold alloy, heavy metals such as Ni and Cr were not isolated at all because gold alloy did not contain such elements but Sn was isolated as much as $227.1{\pm}18.0035{\mu}g/cm^2$ although it was not included in the composition either. Hg was also isolated. These elements are assumed to have been isolated from amalgam itself. Third, when amalgam alloy was apart from gold alloy 0 mm, 7 mm and 40 mm, Cu and Ag showed significance but Hg did not. This suggests that gold alloy must not be used together with amalgam, and must not be used between dissimilar prostheses regardless of distance. Fourth, when amalgam alloy contacted Ni-Cr alloy for crown, Ag was not isolated from the amalgam, but Zn, Ni, Sn, Hg and Cu were isolated in order of quantity. Significance was observed according to distance - 0 mm, 7 mm and 40 mm. Hg was not isolated but heavy metals Ni and Cr were isolated. If amalgam alloy was in the opposite arch or it was apart from Ni-Cr alloy for crown, the isolation Hg was less than that when amalgam alloy contacted Ni-Cr alloy for crown. Fifth, when amalgam alloy contacted Talladium alloy for denture, significance was observed at distances of 0mm, 7 mm and 40 mm. Hg was not isolated but heavy metals Ni and Cr were isolated. If amalgam alloy was in the opposite arch or it was apart from Talladium alloy for denture, the isolation Hg was less than that when amalgam alloy contacted Talladium alloy for denture. Sixth, according to the result of ICPES test on Cu, Sn, Ag, Hg, Zn, Ni and Cr of amalgam alloy, gold ally, Verabond and Talladium alloy when these alloys contacted artificial saliva, significance was observed in Cu and Hg. Seventh, when amalgam alloy contracted two non-precious metals Ni-Cr alloy for crown and Talladium alloy for denture in artificial saliva, significance was observed in the isolated by-products of Hg, Ni and Cr according to distance.