Jun‑Beom Park

Isolation and characterization of human mesenchymal stem cells from gingival connective tissue

BACKGROUND AND OBJECTIVEnThe main purpose of this study was to isolate and characterize gingival connective tissue-derived mesenchymal stem cells (GMSCs). The secondary purpose was to present a modified isolation method for the GMSCs.nnnMATERIAL AND METHODSnCollected healthy gingival tissue samples were de-epithelialized and minced into small fragments. The tissues were digested by dispase and collagenase IV for 30 min. The first digested cell suspension was discarded, and then additional digestion was performed to the remaining cells in the same solution for 90 min. The isolated cells from gingiva was incubated in 37°C humidified condition and observed by inverted microscope. Cytoskeletal morphology was evaluated by phalloidin immunofluorescence. Potency of the cells was tested by colony-forming unit fibroblast assay. GMSCs were characterized by osteogenic, adipogenic and chondrogenic differentiation, and flow cytometric, immunofluorescence analysis.nnnRESULTSnGMSCs showed spindle-shaped, fibroblast-like morphology, colony-forming abilities, adherence to plastic and multilineage differentiation (osteogenic, adipogenic, chondrogenic) potency. GMSCs expressed CD44, CD73, CD90 and CD105, but did not express CD14, CD45, CD34 and CD19 in flow cytometry. Expression of stem cell markers (SSEA-4, STRO-1, CD146, CD166 and CD271) and a mesenchymal marker (vimentin) were observed by immunofluorescence.nnnCONCLUSIONSnIn conclusion, we isolated and characterized stem cells from human gingival connective tissue with modified protocol. GMSCs showed multipotency with high proliferation and characteristics of mesenchymal stem cells. GMSCs are promising sources for tissue engineering and may be obtained during routine procedures under local anesthesia. Further research is needed to evaluate the potential of GSMCs proliferation and cryopreservation.

Evaluation of the effects of Angelicae dahuricae radix on the morphology and viability of mesenchymal stem cells

Angelicae dahuricae radix is a traditional herbal medicine used to treat various diseases in China and Korea, such as colds, headaches, rhinitis and psoriasis. Angelicae dahuricae radix has been used as an anti-inflammatory, analgesic, antipyretic and antioxidant remedy. This study was performed in order to evaluate the effects of the extracts of Angelicae dahuricae radix on the morphology and viability of mesenchymal stem cells derived from the gingiva. Mesenchymal stem cells derived from the gingiva were grown in the presence of Angelicae dahuricae radix at final concentrations that ranged from 0.001 to 100 µg/ml. The morphology of the cells was viewed under an inverted microscope, and the analysis of cell proliferation was performed with cell counting kit-8 (CCK-8) on days 1, 3 and 7. The cells in the control group had spindle-shaped, fibroblast-like morphology at days 1, 3 and 7 under optical microscopy. The shapes of the cells in 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix were similar to the shapes of the cells in the control group. The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10, and 100 µg/ml Angelicae dahuricae radix were 102.5 ± 0.6, 133.3 ± 9.6, 148.4 ± 20.5, 147.7 ± 12.6, 132.3 ± 27.7 and 101.1 ± 4.6%, respectively, when the CCK-8 result of the control group on day 1 was considered to be 100%. There was a marginal increase in cell proliferation at 0.1 and 1 µg/ml groups at day 1; however, this did not achieve statistical significance (P=0.052). The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix were 96.5 ± 1.3, 89.3 ± 0.9, 90.3 ± 3.0, 84.8 ± 12.2, 92.3 ± 4.5 and 86.8 ± 11.7%, respectively, when the CCK-8 result of the control group on day 3 was considered to be 100% (P>0.05). The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix day 7 were 94.9 ± 22.3, 102.8 ± 22.1, 127.4 ± 7.4, 130.4 ± 1.3, 129.2 ± 10.8 and 124.8 ± 9.1%, respectively, when the CCK-8 result of the control group on day 7 was considered to be 100%, but there were no statistically significant differences among the groups (P>0.05). Within the limits of this study, Angelicae dahuricae radix at the tested concentrations did not produce statistically significant differences in the viability of stem cells derived from the gingiva.

The thickness of alveolar bone at the maxillary canine and premolar teeth in normal occlusion

Purpose The main purpose of this study was to investigate bone thickness on the buccal and palatal aspects of the maxillary canine and premolars using cone-beam computed tomography (CBCT). The differences between left- and right-side measurements and between males and females were also analyzed. Methods The sample consisted of 20 subjects (9 males and 11 females; mean age, 21.9±3.0) selected from the normal occlusion sample data in the Department of Orthodontics, The Catholic University of Korea. The thickness of the buccal and palatal bone walls, perpendicular to the long axis of the root were evaluated at 3 mm and 5 mm apical to cemento-enamel junction (CEJ) and at root apex. Results At the canines and first premolars regions, mean buccal bone thickness of at 3 mm and 5 mm apical to CEJ were less than 2 mm. In contrast, at the second premolar region, mean buccal bone thickness at 3 mm and 5 mm apical from CEJ were greater than 2 mm. Frequency of thick bone wall (≥2 mm) increased from the canine to the second premolar. Conclusions This result should be considered before tooth extraction and planning of rehabilitation in the canine and premolar area of maxilla. Careful preoperative analysis with CBCT may be beneficial to assess local risk factors and to achieve high predictability of success in implant therapy.

Effects of tacrolimus on morphology, proliferation and differentiation of mesenchymal stem cells derived from gingiva tissue

Tacrolimus is a 23-membered macrolide lactone with potent immunosuppressive activity that is effective in the prophylaxis of organ rejection following kidney, heart and liver transplantation. Tacrolimus also exerts a variety of actions on bone metabolism. The aim of the present study was to evaluate the effects of different concentrations of tacrolimus on the morphology and viability of human stem cells derived from the gingiva. Gingival-derived stem cells were grown in the presence of tacrolimus at final concentrations ranging from 0.001 to 100 µg/ml. The morphology of the cells was viewed under an inverted microscope and the cell viability was analyzed using Cell Counting kit-8 (CCK-8) on days 1, 3, 5 and 7. Alizarin Red S staining was used to assess mineralization of treated cells. The control group showed spindle-shaped, fibroblast-like morphology and the shapes of the cells in 0.001, 0.01, 0.1, 1 and 10 µg/ml tacrolimus were similar to those of the control group. All groups except the 100 µg/ml group showed increased cell proliferation over time. Cultures grown in the presence of tacrolimus at 0.001, 0.01, 0.1, 1 and 10 µg/ml were not identified to be significantly different compared with the control at days 1, 3 and 5 using the CCK-8 assays. Increased mineralized deposits were noted with increased incubation time. Treatment with tacrolimus from 0.001 to 1 µg/ml led to an increase in mineralization compared with the control group. Within the limits of this study, tacrolimus at the tested concentrations (ranging from 0.001 to 10 µg/ml) did not result in differences in the viability of stem cells derived from gingiva; however it did enhance osteogenic differentiation of the stem cells.

Treatment of dentin hypersensitivity with a low-level laser-emitting toothbrush: double-blind randomised clinical trial of efficacy and safety

Dentin hypersensitivity (DH) is defined as pain derived from exposed dentin in response to chemical, thermal, tactile, or osmotic stimuli that cannot be explained as having arisen from any other dental defect or disease. The aim of this trial was to test the efficacy and the safety of a low-level laser-emitting toothbrush on management of DH. A prospective, double blind, randomised clinical trial was designed; 96 individuals with hypersensitive teeth without caries or fracture were selected as subjects. The subjects were randomly allocated to either the test group with the 635 nm per 6 mW laser-emitting toothbrush, or the control group with the 635 nm per 12.9 μW light-emitting diode (LED) toothbrush. An air blast was applied with a dental air syringe held 3 mm away from the selected tooth and a visual analogue scale (VAS: 0-10) was used to quantify subjective pain. Assessments were completed at a screening visit and after 2-week and 4-week of using a test/control toothbrush. Results demonstrated that the use of both control and test toothbrushes resulted in decreased discomfort after 4 weeks. In the test group, pain intensity scores decreased from 5.8 ± 1.2 to 2.3 ± 1.6, and in the control group, the scores decreased from 6.4 ± 1.3 to 5.5 ± 2.0 (P < 0.05). This decrease was significantly greater in the test group. There were no significant adverse events or side effects. It was concluded that the use of the low-level laser emitting toothbrush is a safe and effective treatment option for the management of DH.

Association of Periodontitis With Urinary Albumin Excretion in Korean Adults With Diabetes: The 2012 Korea National Health and Nutrition Examination Survey

Abstract Albuminuria and periodontitis are both commonly associated with systemic inflammation. However, the association between urinary albumin excretion (UAE) and periodontitis in patients with type 2 diabetes has not been fully investigated. This study aimed to investigate the association between UAE and periodontitis in Korean adults with type 2 diabetes. This study performed a cross-sectional analysis and used hierarchical multivariable logistic regression analysis models. Data from the 2012 Korean National Health and Nutrition Examination Survey were analyzed. A total of 547 patients, with type 2 diabetes without renal impairment, were included in this study. UAE was assessed using the urinary albumin to creatinine ratio (UACR). A community periodontal index greater than or equal to code 3 was used to define periodontitis. The risk of periodontitis tended to increase as UACR increased even after adjustment for potential confounders (P for trend in the odds ratiosu200a=u200a0.05 in model 1; 0.02 in model 2; and 0.01 in model 3). In a subgroup analysis, the prevalence of periodontitis was significantly higher in the patients with albuminuria (UACR >30u200amg/g) than in those without albuminuria among patients younger than 65 years (Pu200a=u200a0.03), those with newly diagnosed diabetes (Pu200a=u200a0.04), or those without obesity (Pu200a=u200a.04). UAE was positively associated with the risk of periodontitis in Korean adults with type 2 diabetes. In the patients who were younger, were newly diagnosed with diabetes, or had normal body mass index, individuals with albuminuria were more likely to have a higher prevalence of periodontitis. Early identification of periodontitis may be helpful in Korean diabetic adults with increased UAE.

Association between underweight and tooth loss among Korean adults.

There is growing interest in the relationship between body mass index and oral health. Previous study showed that being underweight was significantly associated with having lower masticatory performance. This study was performed to assess the relationship between an underweight body mass index lower than 18.5 and the number of natural teeth using nationally representative data. Initially, a total of 25,534 individuals were candidates in the Korean National Health and Nutrition Examination Survey. The analysis in this study was confined to 17,870 subjects who were 19 years or older and without missing values for outcome variables. Body mass index and number of natural teeth were evaluated. Multiple regression analysis was used to evaluate the risk of tooth loss in relation to body mass index. Adjusted odds ratios and their 95% confidence intervals for chewing discomfort in individuals who were underweight, normal, overweight, obese, and extremely obese were 1.712(1.156–2.535), 1.111(0.939–1.315), 1(reference), 0.949(0.798–1.128), and 1.172(0.807–1.700), respectively, after adjustment. The association between underweight and tooth loss was proven by multiple logistic regression analyses after adjusting for confounding factors. Underweight may be considered a potential risk indicator for tooth loss in Korean adults.

Evaluation of the shape, viability, stemness and osteogenic differentiation of cell spheroids formed from human gingiva‑derived stem cells and osteoprecursor cells

The present study was performed to create stem cell spheroids from human gingiva-derived stem cells and osteoprecursor cells and to evaluate the maintenance of the stemness, the viability and osteogenic differentiation of the cell spheroids. Gingiva-derived stem cells were isolated, and a total of 6×105 stem cells and osteoprecursor cells were seeded into concave micromolds at various ratios. Gingiva-derived stem cells and/or osteoprecursor cells formed spheroids in concave microwells. The spheroids demonstrated a smaller diameter when the number of osteoprecursor cells seeded was lower. The majority of cells in the spheroids were identified to be live cells and the cell spheroids preserved viability throughout the experimental period. The cell spheroids, which contained stem cells, were positive for stem-cell markers. Cell spheroids in concave microwells demonstrated a statistically significant increase in alkaline phosphatase activity as time progressed (P<0.05). A statistically significant difference in phosphatase activity was observed in the stem cell alone group when compared with the osteoprecursor cell group at day 5 (P<0.05). Mineralized extracellular deposits were observed in each group after Alizarin Red S staining. Within the limits of the present study, cell spheroids from gingival cells and osteoprecursor cells maintained shape, viability, stemness and osteogenic differentiation potential.

Influence of oral health behavior and sociodemographic factors on remaining teeth in Korean adults: 2010-2012 Korea national health and nutrition examination survey.

AbstractIn this study, the number and location of remaining teeth were analyzed according to sociodemographic variables, anthropometric measurements, and oral health behavior patterns. The hypothesis was that the number and location of remaining teeth would be affected by oral health behavior and by sociodemographic factors, such as education levels, household income, and urban/rural residency.This nationwide cross-sectional study was performed with a total of 36,026 representative Korean adults aged 19 and older. The data were taken from the 2012–2012 Korea National Health and Nutrition Examination Survey.Men had, on average, significantly more remaining teeth than women did. Women brushed their teeth more often than men per day and were more likely to brush their teeth after meals. The participants with higher education levels or household income had significantly more remaining teeth; the number of daily tooth brushing was positively associated with the number of remaining teeth; urban residents had significantly more remaining teeth than rural residents; and elderly adults had fewer remaining teeth than younger adults had (all with Pu200a<u200a0.05). The participants were more likely to retain their incisors (especially their canines) for their entire lifetimes than do so for their molars. From the incisors to the second premolars, they had more mandibular teeth than maxillary teeth, but among molars, they had more maxillary teeth than mandibular teeth. Elementary graduates with low household income had fewer remaining teeth than did university graduates with high household income (Pu200a<u200a0.0001). Finally, participants with high socioeconomic status were more likely to lose their molar teeth than anterior teeth compared to those with low socioeconomic status.The participants who brushed their teeth fewer times per day, those with low household incomes and/or education levels, and those who lived in rural districts had significantly higher prevalence of tooth loss than did other groups in Korean adults. Participants had more anterior and premolar teeth on mandible, but they had more molars on maxilla. In addition, participants with high socioeconomic status were more likely to lose their molar teeth than anterior teeth compared to those with low socioeconomic status.

Use of Confocal Microscopy for Quantification of Plastic Remnants on Rough Titanium After Instrumentation and Evaluation of Efficacy of Removal

PURPOSEnMany experts have proposed the treatment of titanium surfaces with plastic or nonmetal tips to prevent damage to implant surfaces by metal instruments during professional cleaning. It is also known that any material that is softer than titanium may leave remnants of itself on the treated surface. The aim of this study was to quantify the surface area covered by plastic remnants after instrumentation with various plastic instruments and to evaluate the efficacy of the removal of these remnants by confocal microscopy.nnnMATERIALS AND METHODSnTwenty-seven rough-surfaced titanium disks were used for quantification of plastic remnants. Nine disks each were cleaned with (1) a plastic tip on ultrasonic scaler A, (2) a carbon tip on ultrasonic scaler B, or (3) a plastic curette. Three disks from each group were cleaned with a three-way syringe for 10 seconds, and three other disks were cleaned with 0.2% chlorhexidine-soaked cotton pellets. Images were obtained at random areas on each disk with a confocal microscope, and a digital image analysis program was used to quantify the area with autofluorescence.nnnRESULTSnApproximately 10% to 20% of the surface was covered with plastic remnants of the instrument, irrespective of the instrument used. These remnants were not removed with a three-way syringe or chlorhexidine-soaked cotton pellets.nnnCONCLUSIONnPlastic remnants remained after instrumentation, regardless of the instrument used. Moreover, the study highlighted the difficulty of removing all remnants with water spray or a chlorhexidine-soaked cotton pellet. This study suggests that confocal microscopy is a reproducible method for quantification that may be applied for future comparisons of methods to remove plastic residue. Further research is warranted to evaluate the biologic effects of plastic remnants.