• Journal of the korean academy of Pediatric Dentistry
• /
• v.40 no.3
• /
• pp.185-193
• /
• 2013

Mineral trioxide aggregate (MTA) has recently been used as a pulpotomy medicament for primary molars. The aim of this study was to evaluate and compare the proliferation and differentiation potential of dental pulp stromal cells of permanent teeth and deciduous teeth cultured on MTA-coated surface. Human dental pulp stromal cells were obtained from human permanent premolars and deciduous teeth and cultured on MTA-coated culture plates. The cells were subjected to proliferation assay and cell cycle analysis. Their differentiation potential was evaluated by analysing changes in the mRNA expressions of runt-related transcriptional factor 2 (Runx2) and alkaline phosphatase (ALP). Morphological changes of cells in direct contact with MTA were observed using scanning electron microscopy (SEM). The proliferation rates, distribution of cell cycles and mRNA expression patterns of Runx2 and ALP were similar in both types of pulpal cells. SEM observations revealed that both types changed into more dendrite-like cells. On the surface of MTA, human dental pulp stromal cells from deciduous and permanent teeth were able to both proliferate and differentiate into cells that induce mineralization. MTA is suitable as a biocompatible pulpotomy medicament for primary teeth.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.42 no.4
• /
• pp.291-301
• /
• 2015

This study compared the in vitro cell viability and differentiation potentials of human deciduous dental pulp cells (DPCs) on mineral trioxide aggregate (MTA)-like products (ProRoot MTA, RetroMTA and Endocem Zr). The experimental materials were prepared as circular discs, which were used to test the effects of the materials on the viability of human DPCs when placed in direct and indirect contact. Furthermore, the pH of the extracted materials was recorded, and their effect on cell differentiation potential was evaluated by evaluating the alkaline phosphatase (ALP) activity and Alizarin Red S staining of DPCs incubated with the test materials. In direct contact, the cell viability of human DPCs was higher with ProRoot MTA and RetroMTA than with Endocem Zr. However, when in indirect contact, the cell viability of human DPCs was generally higher in Endocem Zr than in ProRoot MTA and Retro MTA. With respect to pH, the alkalinity was lower for Endocem Zr than for the other test materials. The ALP activities of the cells were not enhanced by any of the experimental materials. Alizarin Red S staining of the tested human DPCs revealed that their differentiation potential was lower than for cells incubated with osteogenic induction medium. While there were differences in the responses of the human DPCs to the test materials, all displayed degrees of cytotoxicity and were unable to enhance either the viability or differentiation of human DPCs. However, Endocem Zr exhibited better cell viability and was less alkaline than the other test materials.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.41 no.1
• /
• pp.1-7
• /
• 2014

If it is possible to preserve and culture cells from exfoliated deciduous teeth in a readily available storage medium within each family, more stem cells would be obtained. This research is about the effect of storage media and time on pulpal cell viability of exfoliated deciduous teeth. 330 exfoliated deciduous teeth were randomly divided into 11 groups; fresh group, dry group, groups stored in cell culture medium (2, 4, 7 days each), in milk (2, 4, 7 days each), and in saline (2, 4, 7 days each). Primary culture of pulpal cells was conducted in each group and the success rates were compared by calculating the number of teeth with viable cells. The result of primary culture shows that the success rate decreases as the time of storage gets longer. There was no statistical difference between groups stored in the cell culture medium, milk, and saline for 2 and 4 days. However, the groups stored in milk and saline for 7 days showed dramatic decrease in success rate compared to the group stored in the cell culture medium. In conclusion, exfoliated or extracted deciduous teeth can be used to culture pulpal cells when they are stored in milk and saline for a certain period of time; however obtaining viable pulpal cells becomes harder as the storage time gets longer.

• The korean journal of orthodontics
• /
• v.35 no.2 s.109
• /
• pp.106-115
• /
• 2005

This study was aimed to investigate the effects of indomethancin on physiologic root resorption and to examine the dental pulp and tissue changes around the resorbing teeth 13-14 week old six mongrel dogs were divided into 3 groups, two experimental groups administered indomethacin 2mg/kg/day and 8mg/kg/day orally two times a day for 14 days respectively. and control group administered a placebo The deciduous incisors showing root resorption were selected. fixed for 24 hrs in $10\%$ formalin solution. demineralized in $10\%$ EDTA solution. Invested in paraffin and sectioned in $5{\mu}m$ thick sections. The preparations were stained with H&E staining and Masson's trichrome staining and examined under the light microscope Observation revealed that deciduous root resorbing tissue resembles inflammatory tissue and accompanies bore remodelling. The dental pulp was formal except the area near root resorption. well organized columnar odontoblasts layer under the predentin, anud the odontoblasts near root resorption were cuboidal or flat cells in the disrupted layer under the predentin. Indomethacin administered group showed a partial decrease in the number of odontoclasts and nucleus But there was no sign of pulp change by indomethacin. These results suggest that indomethacin inhibits recruitment of odontoclasts partially and that of osteoclasts more. and so when it is administered for long periods deciduous root resorption can be delayed and eruption of the successor can be delayed for a short period.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.27 no.1
• /
• pp.77-84
• /
• 2000

Although ferric sulfate has been proposed as an alternative to formocresol in pulpotomy treatment in primary teeth, it has been given little concern regarding its cytotoxicity and mutagenicity. In the present study, we assessed the in vitro genotoxic effect of a ferric sulfate on human gingival fibroblast cell line (HGF-1). DNA damage was evaluated using comet assay (single cell alkaline gel electrophoresis) and obtained the results as follows: 1. A dose-response relationship was found between ferric sulfate concentrations (0 to 5mM) and DNA damages. 2. Above the concentration of 0.1mM, DNA damage was significantly increased than those of the control (p<0.05). 2. At the fixed concentration of 0.05mM, no significant difference was found between exposure time and DNA damage. These findings suggest that ferric sulfate as a pulpotomy agent can induce DNA damage in human gingival fibroblasts.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.27 no.1
• /
• pp.151-160
• /
• 2000

The effect of concentration as factor in cytotoxicity, protein synthesis and alkaline phosphatase activity was compared for pulpotomy medicaments (formaldehyde, formocresol, paraformaldehyde, ferric sulfate) Human pulp fibroblasts were exposed to a range of concentrations(0.01, 0.05, 0.10, 0.25, 0.50, $1.00{\mu}l/ml$) of each agents, for period of 24hrs. The cell activities were evaluated by MTT assay, protein assay and alkaline phosphatase activity examination. The results as follows : 1. After 24hrs culture, pulp fibroblasts adding formaldehyde, formocresol and paraformaldehyde were suppressed cell activities with concentration increasing, but, no depression of cell activities by ferric sulfate. No significant difference was in formaldehyde, formocresol and paraformaldehyde. 2. Protein synthesis by pulpotomy agents were not significant difference in pulp fibroblasts but protein synthesis were a little decreased by paraformaldehyde. 3. Alkaline phosphatase activity was a little decreased by pulpotomy medicaments.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.2
• /
• pp.291-305
• /
• 1996

The purpose of this study was to investigate the distribution of nerves in the dental pulp of early extracted primary teeth, normal exfoliated primary teeth, partially-erupted, nonfunctional, premolars, and erupted, functional, premolars. Numbers of sample were 10 teeth in each group. The distribution of nerves in the dental pulp were investigated by means of immunohisto chemistry for detection of neurofilament protein(NFP). The results were as follows: The early extracted primary teeth exhibited patterns of innervation similar to those observed for young permanent teeth. The plexiform arrangement of fibers was not evident in the primary teeth. Most nerves appear to terminate about the odontoblasts. As primary teeth began to undergo root resorption, degenerative changes such as vesicles and fragmentation appear in the nerves. The quantity of neural tissue also decreased. In teeth in which the roots were almost completely resorbed only a small number of nerves remain. There was a decrease in the number of terminal branches in the pulp of the partially erupted, nonfunctional, premolars and those present reached the pulpo-odontoblastic border. The nerve terminals in the pulp of the erupted, functional, premolars were traced to the dentinal tubule and a few nerve fibers formed loops in the predentin.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.40 no.3
• /
• pp.177-184
• /
• 2013

Calcium hydroxide mixture medicaments can nearly be considered to be the ideal primary tooth filling material. However, long-term application of calcium hydroxide combinations as an intra canal medicament softens dentin. The aim of this study was to evaluate the effect of calcium hydroxide on the microhardness of root dentin of primary tooth. For the study, 60 extractedprimary incisors were divided into 3 groups (no medicament, calcium hydroxide/iodorform mixture, and calcium hydroxide/distilled water mixture). After the cleansing and shaping of canals, calcium hydroxide medicaments were applied and stored for different periods of time (1, 7, 30, 90 days). The root was horizontally sectioned into 2 mm thick specimens and the microhardness was measured using Vickers microhardness tester. The results were as follows : Root dentin microhardness of primary teeth decreased with long term exposure to calcium hydroxide medicaments according to the experimental period and showed statistically significance (p < 0.05). Root dentin microhardness of primary tooth filled with calcium hydroxide mixed with distilled water showed more decrease than filled with Vitapex and showed statistically significance (p < 0.05). Root dentin microhardness of a control group without exposure to calcium hydroxide decreased according to the experimental period and showed statistically significance (p < 0.05).

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.2
• /
• pp.196-203
• /
• 2003

The application of sealants is a highly technique-sensitive procedure, requiring an extremely dry field prior to placement. Moisture contamination of the etched enamel surface before sealant placement is cited as the main reason for sealant failure. The purpose of this study was to evaluate the effects of different methods of sealant application on the shear bond strength of sealants to enamel. In groups 1, 2, 3, 4 Teethmate(unfilled sealant) was used, while Ultraseal XTplus(filled sealant) was used in groups 5, 6, 7, 8. Groups 1 and 5(control) were acid etched for 15 seconds using 35% phosphoric acid, washed and then dried. In groups 2, 6 drying agents were applied, and in groups 3, 7 bonding agents were applied and light cured. In groups 4 and 8 both drying agent and bonding agent were applied. Then sealant was cured to the specimen using molds 3mm in diameter and 2mm in height. Thermocycling was performed and shear bond strength was finally measured. The following results were obtained : 1. Groups using filled sealant(groups 5, 6, 7, 8) showed higher shear bond strengths compared to groups using unfilled sealant(groups 1, 2, 3, 4). 2. Among groups using unfilled sealant(groups 1, 2, 3, 4), groups 2, 3, 4 showed significantly higher shear bond strength compared to group 1(p<0.05). There were no significant differences among groups 2, 3 and 4. 3. There were no significant differences(p>0.05) among groups using filled sealant(groups 5, 6, 7, 8). 4. When modes of fracture were examined, cohesive failure was observed in groups 2, 3 and 4.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.3
• /
• pp.239-249
• /
• 2001

The purpose of this study is to evaluate the relationship of the factors which could be influenced by orthognathic surgery especillay SSRO. We measured the amounts of the maximum opening, lateral movements, maximum velocity and pattern of mandibular path during the opening and closing of mandible at the following times ; preoperative, 1 month after operation, 6 months after operation respectively using MKG. And the results were compared according to the categorized subgroups. Following results were obtained : 1. The change of the amounts of mandibular lateral movement and maximum opening velocity were statistically different between male and female (p<0.05), but the others were not. 2. According to the method of operation, there was no difference in the change of the mandibular movements between the group of SSRO and SSRO plus LeFort I osteotomy (p>0.05). 3. According to the amounts of mandibular movement, the recovery of left lateral movement of the group of $6{\sim}10mm$ was better than the other groups (p<0.05). 4. In the frontal pattern of the opening and closing of the mandible, the complex deflected type (F5), simple deflected type (F4), complex deviated type (F3), simple deviated type (F2), straight type (F1) were obtained in order at the time of preoperative, simple deflected type, simple deviated type, complex deviated type, straight type, complex deflected type in order at the time of 1 month after surgery, and the result at the time of 6 months after surgery was the same with that of the time of preoperative. In the sagittal pattern, non-coincident type (S2) was predominant at the time of preoperative, and coincident type (S1) was predominant at the time of 1 month after surgery. After 6 months, the result was also the same with that of the preoperative in sagittal pattern. 5. There was not a statistical difference in the change of the mandibular movement between group of presence of the preoperative TMJ symptoms and non-presence group (p>0.05). 6. There was not a statistical difference in the change of the mandibular movement between repositioning device applied group and non-applied group (p>0.05). 7. Sixty three percents of the patients who had preoperative TMJ symptoms were improved after surgery and preoperative TMJ symptoms were more improved after operation in the repositioning device non-applied group statistically (p<0.05).