• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.2
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• pp.164-169
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• 2017

Dentinogenesis imperfecta type II (DGI-II) is an inherited disorder affecting the dentin matrix and is related to mutations in the dentin sialophosphoprotein (DSPP) gene. The protein encoded by the DSPP gene undergoes extensive posttranslational modifications. Dentin phosphoprotein (DPP), one of the DSPP expressed products, has unique composition with highly repetitive Asp-Ser-Ser amino acid residues and is related to the maturation of dentin mineralization. We aimed to identify mutation in DSPP, including the DPP coding region, contributing to inherited dentin defects in a Korean family with DGI-II. Clinical and radiographic examinations were performed, and all five exons and exon-intron boundaries of the DSPP gene were sequenced. Additionally, allele-specific cloning for highly repetitive DPP region was performed. By sequencing and cloning, a heterozygous single nucleotide deletion (c.2688delT) was identified. The identified mutation caused a frameshift in the DPP coding region. This frameshift mutation would introduce hydrophobic amino acids instead of hydrophilic amino acids and would result in a change in the characteristics of DPP.

• Restorative Dentistry and Endodontics
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• v.40 no.4
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• pp.290-298
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• 2015

Objectives: Sodium hypochlorite (NaOCl) is an excellent bactericidal agent, but it is detrimental to stem cell survival, whereas intracanal medicaments such as calcium hydroxide ($Ca[OH]_2$) promote the survival and proliferation of stem cells. This study evaluated the effect of sequential NaOCl and $Ca(OH)_2$ application on the attachment and differentiation of dental pulp stem cells (DPSCs). Materials and Methods: DPSCs were obtained from human third molars. All dentin specimens were treated with 5.25% NaOCl for 30 min. DPSCs were seeded on the dentin specimens and processed with additional 1 mg/mL $Ca(OH)_2$, 17% ethylenediaminetetraacetic acid (EDTA) treatment, file instrumentation, or a combination of these methods. After 7 day of culture, we examined DPSC morphology using scanning electron microscopy and determined the cell survival rate with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. We measured cell adhesion gene expression levels after 4 day of culture and odontogenic differentiation gene expression levels after 4 wk using quantitative real-time polymerase chain reaction. Results: DPSCs did not attach to the dentin in the NaOCl-treated group. The gene expression levels of fibronectin-1 and secreted phosphoprotein-1 gene in both the $Ca(OH)_2$- and the EDTA-treated groups were significantly higher than those in the other groups. All $Ca(OH)_2$-treated groups showed higher expression levels of dentin matrix protein-1 than that of the control. The dentin sialophosphoprotein level was significantly higher in the groups treated with both $Ca(OH)_2$ and EDTA. Conclusions: The application of $Ca(OH)_2$ and additional treatment such as EDTA or instrumentation promoted the attachment and differentiation of DPSCs after NaOCl treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.4
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• pp.312-318
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• 2015

The aim of this study was to investigate the possibility of the supernumerary teeth for the stem cell source in dentistry. The Real Time Quantitative Reverse Transcription Polymerase Chain Reaction (Real Time qRT-PCR) method was used to evaluate the differentiation toward the odontoblast of the supernumerary dental pulp stem cells (sDPSCs). Supernumerary dental pulp stem cells were obtained from 3 children (2 males and 1 female, age 7 to 9) diagnosed that the eruption of permanent teeth was disturbed by supernumerary teeth. The common genes for odontoblasts are alkaline phosphatase (ALP), osteocalcin (OC), osteonectin (ON), dentin matrix acidic phosphoprotein 1 (DMP-1), dentin sialophosphoprotein (DSPP). The sDPSCs were treated for 0 days, 8 days and 14 days with additives and then Real Time qRT-PCR was performed in intervals of 0 days, 8 days and 14 days. The alizarin-red solution staining was performed to visualize the stained color for the degree of calcification at 7 days, 14 days, 21 days and 28 days after treating additives to the sDPSCs. From the result of the Real Time qRT-PCR, the manifestation exhibit maximum value at 8 days after additive treatment and shifted to a decrease trend at 14 days. Alizarin-red solution staining exhibit light results at 7 days after staining and generalized dark result at 14 days. Consequently, in studies with sDPSCs, appropriate treatment time of additives for Real Time qRT-PCR is 8 days. Also, a suitable period of Alizarin-red solution staining is 14 days.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.219-225
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• 2019

The purpose of this study was to investigate the odontoblast gene expression related to the subculture speed of supernumerary dental pulp stem cells (sDPSCs). The stem cell is undifferentiated cells which has the ability to differentiate into various cells. Specific stimulation or environment induces cell differentiation, and these differentiation leads to bone or muscle formation. 20 sDPSCs were obtained from 20 children under aseptic condition. During the culture through the 10th passage, the third passage cells which showed short subculture period and 10th passage cells which showed long subculture period were earned. Each cell was divided into differentiated group and non-differentiated group. Quantitative real-time polychain reaction (q-RT-PCR) was performed for each group. The genes related to odontoblast differentiation, Alkaline Phosphatase (ALP), Osteocalcin (OCN), Osteonectin (ONT), Dentin sialophosphoprotein (DSPP) and Dentin matrix acidic phosphoprotein 1 (DMP-1), were measured. Differentiated cells showed more gene expression levels. Undifferentiated cells showed higher gene expression level in 10th passages but differentiated cells showed higher gene expression level in 3rd passages. Cells that showed faster subculture period showed relatively lower gene expression level except for OCN and DSPP.