• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.597-610
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• 2001

Normal gingival fibroblasts functioning is fundamental for the maintenance of periodontal connective tissue as well as wound healing. Nicotine have been found to affect DNA synthesis and cell proliferation, which appear to depend on the type of cells. This in vitro study was done to determine the effects of nicotine, a major component of tobacco, on cell proliferation, viability, activity, cell cycle distribution, and expression of cell cycle regulatory proteins in human gingival fibroblasts. Nicotine has been tested for 2 days or 4 days in 5 different concentrations; $0.1{\mu}g/ml$; $1{\mu}g/ml$; $10{\mu}g/ml$; $100{\mu}g/ml$; $1000{\mu}g/ml$. To assess cell proliferation and viability, viable and non-viable cells were counted by hemocytometer; to evaluate cellular activity, MTT assay was employed; to analyze cell cycle distribution, fluorescent propidium iodide-DNA complex were measured using fluorocytometer; to determine the expression of cell cycle regulatory proteins, western blot analysis was performed. After 2 days and 4 days incubation respectively, at concentrations of $1{\mu}g/ml$ - $1000{\mu}g/ml$, nicotine significantly inhibited proliferation comparing to non-supplemented controls. The cell viability was significantly decreased after 2 days and 4 days at concentrations of $1{\mu}g/ml$ - $1000{\mu}g/ml$ and at $10{\mu}g/ml$ - $1000{\mu}g/ml$ respectively. After 2 days and 4 days, the cellular activity was significantly decreased at concentrations of $10{\mu}g/ml$ - $1000{\mu}g/ml$. Treatment with $100{\mu}g/ml$ nicotine for 48 hours caused an increase in the proportion of G1-phase cells (from 46.41% to 53.46%) and a decrease in the proportion of S-phase cells (from 17.80% to 14.27%). The levels of cyclin $D_1$ and CDK 4 proteins in nicotine-treated fibroblasts were lower than that of controls, whereas the levels of p16 and pRB were higher than that of controls. These results suggest that the decrease of cell proliferation and lengthened Gap phases (G1) by nicotine may due to the increased expression of p16 and pRB as well as decreased expression of cyclin $D_1$ and CDK 4 in human gingival fibroblasts.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• Journal of Periodontal and Implant Science
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• v.29 no.2
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• pp.401-415
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• 1999

Root surfaces affected by periodontal disease undergo various forms of changes. Cementum exposure from gingival recession may result in absorption of calcium, phosphorus, and fluoride and subsequent hypermineralization and increased radiodensity. Although some reports have suggested that inorganic content with root cementum might show various changes depending upon age or extent of periodontal disease, but no consensus can be reached regarding the the distribution of various elements. The present study examines the difference in mineral content between healthy and periodontal diseased roots by analyzing three areas per tooth along the root surface in cervico-apical direction using electron probe and scanning electron microscope. Healthy tooth that was extracted for orthodontic purpose was used as control. Experimental teeth include those with periodontal pocket depth exceeding 6mm and those with gingival recession and periodontal pocket depth of 2-4mm. Levels of Ca, P, Mg and Na were measured using wavelength dispersive x-ray spectrometer at three areas per tooth. The examined areas were located apical to cemento-enamel junction in control and periodontal ligament-depleted areas in experimental teeth. The corresponding areas were also examined with scanning electron microscope(x70) The results are as follows. 1. Minerals were detected in order of Ca, P, Mg and Na. In all root surfaces, levels of Ca and P were higher in dentin than in cementum. 2. Level of Mg was twice as high in dentin than in cementum. There was no significant difference in the level of Mg and Na between normal and periodontal diseased roots or between the various locations in the same root. 3. Level of Ca and P in the surface cementum showed no difference between normal and periodontal diseased root, although the areas in dentin with high level of either ion also showed high level of corresponding ion in cementum. 4. Difference in the Ca and P content between various locations within the same root was noted, although no coherent pattern existed. These results suggest that although the mineral content of the root cementum in periodontitis-affected tooth is affected by exogenous ions from saliva and food, but there was no difference in the mineral contents between normal and periodontally diseased root.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.109-126
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• 1993

Refractory periodontitis manifest progressive attachment loss in a rapid and unrelenting manner regardless of the type or frequency of therapy applied. The purpose of this study was ta evaluate the relation between the level of cytokines in GCF and periodontopathic microflora with disease activity of refractory periodontitis. Selection of patients with refractory periodontitis (7 males, 3 females) were made by long term clinical observation including conventional clinical history and parameters. Teeth that showed pocket depth greater than 6mm were selected as sample teeth. Subjects were examined at baseline and after 3 months. Prior to baseline test, individual acrylic stent was fabricated. Reference grooves were made on each sample tooth site. Pocket depth and attachment loss were measured by Florida Probe. Gingival index was measured at 4 sites each sample teeth. Disease activity was defined as attachment loss of ${\ge}$ 2.1mm, as determined by sequential probing and tolerance method. The pattern and amount of alveolar bone resorption was observed with quantitative digital subtraction image processing radiography. Morphological analysis of subgingival bacteria was taken by phase contrast microscopy. Predominant cultivable bacterial distribution and frequency were compared between disease-active and disease-inactive site using immunofluorescence microscopy and selective microbial culturing. Levels of $interleukin-l{\beta}$, 2, 4, 6 and $TNF-{\alpha}$ in GCF and blood serum sample were quantified by ELISA. In active sites, P. intermedia was significantly increased to compare with inactive site. $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF were increased in active sites and IL-2 in serum was increased in active patients significantly. Alveolar bone loss in active site was correlated with $IL-1{\beta}$, IL-2 in GCF. And loss of attachment in active site was correlated with IL-2 in GCF. These results demonstrate that IL-2 in serum, $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF, P, intermedia might be used as possible predictors of disease activity in refractory periodontitis before it is clinically expressed as attachment loss and quantitative alveolar bone change.

• Journal of Periodontal and Implant Science
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• v.24 no.2
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• pp.340-356
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• 1994

The purpose of this study was to assess the clinical and microbiological effect of chlorhexidine rinse and supragingival plaque control following scaling and root planing on adult periodontal disease. 14 patients with adult periodontitis were selected for the study . They had not taken antibiotics for 6 months and history of dental treatment for 6 months before the study. Patients received a supragingival scaling and root planing under local anesthesia, plaque control group was subjected to professional plaque control 2 times for a period 2 week, chlorhexidine rinse group were subjected to twice daily 0.2% chlorhexidine rinse for a period 2 week. Clinical examination (plaque index, gingival index, probing pocket depth) and distribution of the bacteria morphology of subgingival plaque were monitored on baseline (0 week), 1 week, 2 week, 4 week and 6 week. The results were as follows : 1. Plaque index in chlorhexidine rinse group , plaque control group and control group was significantly reduced during all weeks (P<0.05). 2. Probing pocket depth was significantly reduced at 2, 4, 6 week (P<0.05) in chlorhexidine rinse group and control group, plaque control group was significantly reduced during all weeks (P<0.05). 3. Gingival index was significantly improved at 2, 4, 6 weeks(P<0.05) in chlorhexidine group and plaque control group, control group was significantly improved at 1, 2, 4 weeks (P<0.05). 4. Percentage of cocci was significantly increased at 1, 2, 4 and 6 weeks in chlorhexidine rinse group and control group, plaque control group was significantly increased at 2, 4 and 6 weeks(P<0.05). 5. Percentage of non-motile rods in all group were not significantly changed when compared with those of baseline (0 week) (P<0.05). 6. Percentage of motile rods was significantly reduced during all weeks (P<0.05) in chlorhexidine rinse group, plaque control group was significantly reduced at 2, 4, 6 weeks and 1, 2 and 4 weeks in control group. 7. Percentage of spirochetes was significantly reduced during all weeks (P<0.05), plaque control group was significantly reduced at 2, 4, 6 weeks and 1, 2, 4 weeks in control group. This results were suggested that clinical and microbiological effect of chlorhexidine rinse and supragingival plaque control following scaling and root planing on periodontal disease

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.699-721
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• 1996

브로네마르크가 골유착성 임플랜트를 소개한 이래로, 현재 골유착성 임플랜트에 의한 치료는 안전하고 안정적인 방법으로 여겨지고 있다. 골유착성 임플랜트를 이용한 초기의 치료는 무치악 환자의 저작기능 회복에 중점을 두어 왔다. 그러나 현재는 환자와 시대의 요구에 따라서 심미성이 주요한 관심사가 되었다. 그래서 표준 지대주보다 더 심미적인 지대주 시스템들이 개발되었다. 다양한 직경의 임플랜트 고정체에 관한 임상가들의 요구에 의해 직경 이 큰 고정체가 생산되기 시작했으며, 5mm의 직경을 갖는 고정체가 그 예이다. 골유착성 임플랜트를 사용하여 보철치료를 할 때, 골과 고정체의 계면은 보철물과 지대주에 가해지는 교합력을 인접골에 전달하게 되며, 이것은 계면에 생물학적인 반응을 야기할 수 있다. 임플랜트의 형태는 골흡수와 같은 바람직하지 않은 반응을 일으키지 않도록 고안되어야 하며, 임플랜트 자체가 교합력을 견딜 수 있어야 한다. 그러므로 골유착성 임플랜트 시스템을 임상에 사용하려고 할 때 이것의 생역학적 분석은 반드시 필요하다. 본 연구에서는 삼차원 유한요소분석적 방법을 사용하여 3.75mm직경을 갖는 고정체에 표준 지대주, 이세티콘 지대주, 마이러스콘 지대주를 연결한 모델과 5mm 직경을 갖는 고정체에 표준 지대주를 연결한 모델에 각각 수직하중, 경사하중, 수평하중을 가했을 때의 응력분포를 비교하였다. 본 연구의 결과는 다음과 같다. 1. 모든 모델에서 금나사의 경부, 금원주, 지대주에 응력의 집중이 일어났다. 2. 임플랜트 고정체에서는 고정체 상방 2/3, 그리고 지대주와 접촉하는 고정체 상면에서 응력의 집중이 관찰되었다. 3. 골에서는 상부 피질골에 응력의 집중이 관찰되었으며, 해면골에서는 두드러진 응력의 집중을 보인 부위는 없었으나 고정체의 근단부 주위 해면골에서의 응력값이 비교적 높았다. 4. 5mm 직경의 고정체를 사용하지 않은 모델 중에서, 표준 지대주를 사용한 경우가 가장 응력분산에 유리하였으며 마이러스콘 지대주를 사용한 경우가 가장 불리하였다. 5. 3가지 하중 조건하에서 수평하중과 경사하중의 경우가 수직하중의 경우보다 더 높은 응력값이 관찰되었다. 6. 응력값은 골에서보다 임플랜트 내부에서 훨씬 높았다.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.591-600
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• 2006

Purpose: This study assessed the impact of self-reported periodontal health on the oral health-related quality of life among elderly Koreans. Methods: Four hundred twenty one elderly Koreans in Seoul and suburban areas were selected with a cluster (institution) sampling method, and were requested to take oral examinations and finish questionnaires on the Oral Health Impact Profile-14(OHIP-14). and self-reported periodontal health status, such as periodontal symptoms, self-rated periodontal health and periodontal treatment need. As the dependent variable, OHIP-14 showed a positive skewed distribution (skewness: 1.17), we transformed to square-root form to apply parametric analyses. Bivariate analysis by t-test and ANOVA, and multivariate analysis with the two-level regression model accounting clusters were implemented. Results: Mean age of the subjects was 74.6 years and 66.5% were women. Fourteen items of OHIP-14 were summarized to one factor explaining 78.6% of total variance and produced the Chronbach alpha coefficient of 0.92. Results from the multivariate model, adjusting for age, sex, type of institutions, ability to pay, and number of teeth present, showed significantly lower OHIP-14 with reporting less than 3 periodontal symptoms (p(O.OOO1), rating their own periodontal health as above average level (p=O.0144), and thinking they don't need any periodontal treatments in the near future (p=O.0148), than their counterparts. The intraclass-corrrelation estimated by the final model was 0.028. Conclusion: This study demonstrates a significant association between self-reported periodontal health status and the oral health-related quality of life.

• Journal of Periodontal and Implant Science
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• v.43 no.2
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• pp.72-78
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• 2013

Purpose: The purpose of this study was to compare the phototoxic effects of blue light exposure on periodontal pathogens in both planktonic and biofilm cultures. Methods: Strains of Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis, in planktonic or biofilm states, were exposed to visible light at wavelengths of 400.520 nm. A quartz-tungsten-halogen lamp at a power density of $500mW/cm^2$ was used for the light source. Each sample was exposed to 15, 30, 60, 90, or 120 seconds of each bacterial strain in the planktonic or biofilm state. Confocal scanning laser microscopy (CSLM) was used to observe the distribution of live/dead bacterial cells in biofilms. After light exposure, the bacterial killing rates were calculated from colony forming unit (CFU) counts. Results: CLSM images that were obtained from biofilms showed a mixture of dead and live bacterial cells extending to a depth of $30-45{\mu}m$. Obvious differences in the live-to-dead bacterial cell ratio were found in P. gingivalis biofilm according to light exposure time. In the planktonic state, almost all bacteria were killed with 60 seconds of light exposure to F. nucleatum (99.1%) and with 15 seconds to P. gingivalis (100%). In the biofilm state, however, only the CFU of P. gingivalis demonstrated a decreasing tendency with increasing light exposure time, and there was a lower efficacy of phototoxicity to P. gingivalis as biofilm than in the planktonic state. Conclusions: Blue light exposure using a dental halogen curing unit is effective in reducing periodontal pathogens in the planktonic state. It is recommended that an adjunctive exogenous photosensitizer be used and that pathogens be exposed to visible light for clinical antimicrobial periodontal therapy.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.209-223
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• 2013

This study was to evaluate the stress distributions of prefabricated, customized abutments and fixtures according to their material and shape by three-dimensional finite element analysis. And to investigate the fatigue life and fracture characteristics. Mandibular models were fabricated by reconstruction of the CT scan of patients with normal occlusion. A total of six finite element models were designed, a load of 100 N was applied on the buccal cusps vertically, and 30 degree obliquely. 10 specimens each were fabricated for the more clinically widely used 4 type abutments and were loaded according to ISO 14801. Differences in stress distribution patterns were not found according to the materials of the abutments and fixtures. But a slight difference in the stress level was detected. Customized abutment groups showed lower crown stress levels. One-piece zirconia implant showed the lowest bone stress levels. In the fatigue test, highest values were measured in group 7. Prefabricated abutments showed less variation of fatigue life (P<0.05). Use of customized abutments can improve the fracture resistance of restorations. Especially, use of customized zirconia abutments reinforced by titanium screw connecting parts is recommended.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.41-49
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• 2002

The aim of this study was to compare periodontal conditions around mesially tipped molars by a tipping degree. Patients who had been consecutively treated at the Department of Periodontology, Chonbuk National University Hospital from October 1999 to August 2001 were assessed with radiographs taken at their molar regions. Of all molars investigated, 142 molars of 116 patients tipped mesially more than 10 degrees to the line perpendicular to an occlusal plane were selected for the study. The tipped molars were divided into 2 groups with a reference to a tipping degree, i.e., 66 slightly tipped(group 1 : <$30^{\circ}$) and 76 severely tipped molars (group 2 : ${\geq}30^{\circ}$). Probing depth(PD), plaque retention index(PRI) at mesial surfaces of tipped molars and tooth mobility(TM) were recorded at the clinical examination. Tipping degree(TD) and alveolar bony defect(ABD) at the mesial surface of the molars were measured in a radiograph. The results showed that no statistical differences were found between groups in all measured variables. In Pearson correlation analysis performed in the same group, a positive relationship was shown between PRI and PD in the group 1 and, in the group 2, between PRI and PD as well as PRI and ABD(p < 0.01). However, no statistically significant relationship was found between TD and all other variables in both groups. Within limitations of this study, it may be concluded that tipping degree did not seem to influence periodontal conditions, i.e., PD, ABD and TM of mesially tipped molars per se, but plaque presence/absence seemed to mainly affect the periodontal conditions of the tipped molars.