• The korean journal of orthodontics
• /
• v.25 no.5 s.52
• /
• pp.525-541
• /
• 1995

This study was designed to investigate force systems and tooth movements produced by retraction archwire during retraction of four maxillary incisors after the maxillary canine retraction into the maxillary first premolar extraction space using the computer-aided three-dimensional finite element method. A three-dimensional finite element model, consisting of 2248 elements and 3194 nodes, was constructed. The model consisted of maxillary teeth and surrounding periodontal membranes, .022'$\times$.028'-slot brackets, and 5 types of retraction archwires(.019'$\times$.025' stainless steel archwire) modeled using the beam elements. The contact between the wire and the bracket slot was modeled using the gap elements because of the non-linear elastic behaviors of the contact between them. The forces and moments, End displacements produced by retraction archwire were measured at various conditions to investigate the difference according to types of loops, magnitudes of activation force, gable angle, and anterior lingual root torque. The results were expressed quantitative and visual ways in the three-dimensional method. The following conclusions can be drawn from this study.1. When the tear-drop loop archwire was activated, the mesio-distal and lingual translational movements of the teeth helped to close the extraction space, but unwanted movements of the teeth including intrusions and extrusions, and rotational movements in each direction occurred. 2. Activation of T-loop archwire compared with those of other types of retraction archwires produced the least translational movements of the teeth helped to space closure and also the least unwanted movements of the teeth. 3. Increasing amount of activation in the tear-drop archwire led not only to increase of translational movements of the teeth helped to space closure, but also to increase of unwanted movements of the teeth. 4. Addition of gable bend in the tear-drop archwire helped anterior teeth to translational movements in the mesio-distal direction, but increased unwanted movements of the teeth 5. Addition of anterior lingual root torque in the tear-drop archwire helped central and lateral incisor to improve their facio-lingual inclination, but increased unwanted movements of the teeth.

• The korean journal of orthodontics
• /
• v.29 no.4 s.75
• /
• pp.483-490
• /
• 1999

Interdental enamel stripping is an usual method for correction of abnormal tooth shape and tooth size discrepancy which is one of the etiologic factors of malocclusion. Clinically it Is useful to correct the minor crowding in anterior teeth and posterior occlusion during finishing stage of orthodontic treatment. But this procedure has risks such as irreversible tooth reduction and remaining roughness of enamel surface can accumulate plaque which can evoke periodontal problem. Even if various methods were introduced to minimize the enamel surface roughness, their evaluation was limited in morphologic differences by scanning electronic microscope(SEM). The purpose of this study was to compare the various interdental enamel stripping method by SEM and to quantify the difference of surface roughness by use of Surfcorder SEF-30D(Kosaka Lab. Ltd.) which can measure the roughness of surface. The stripping methods were divided into mechanical and mechanical-chemical method. Air-rotor stripping and separating strip were used for mechanical stripping and $37\%$ phosphoric acid was used for chemical stripping. The enamel surface roughness after mechanical or mechanical-chemical stripping of interproximal surfaces of premolars which were extracted for orthodontic purpose were measured and compared by means of SEM and $Surfcorder^{\circledR}$, the results were as follows. 1. Enamel surface of primary treated by coarse diamond bur and separating strip groups showed highest value of roughness. 2. To compare the primary treated groups between mechanical and mechanical-chemical method, the latter group showed lower value of roughness remarkably. 3. Mechanical stripping groups which were treated both coarse and fine instrument showed lower value of roughness as much as non treated group. 4. The use of Pumice for final polishing did not show significantly smoothening the stripped enamel surface any more.

• The korean journal of orthodontics
• /
• v.28 no.4 s.69
• /
• pp.563-580
• /
• 1998

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal on masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal on masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth displacement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch wire, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased 3. When MDAW and Class II elastics were applied, the teeth movement were sir flu with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.

• Journal of Oral Medicine and Pain
• /
• v.35 no.1
• /
• pp.31-39
• /
• 2010

This study is to observe the bacteriocidal effect of the Low Level Laser (LLL) against oral microorganisms which are related to the occurrence of periodontal diseases and oral malodors. The Porphyromonas gingivalis 2561 (P. gingivalis 2561) and Prevotella intermedia (Pr. intermedia) were treated with photosensitizing substance-toluidine blue O (TBO; C.I. 52040) and then radiated with the LLL which has 650nm wavelength for 1, 2, 3 and 5mins. continuously upon varying distances of 1, 2 and 3cm for each experimental groups. The results are as follows; 1. The P. gingivalis 2561 which was treated with TBO and then radiated with LLL at a distance of 3cm for 1min. showed 99.99% higher antibacterial effect in comparison to the experimental group treated only with TBO. 2. The Pr. intermedia which was treated with TBO and then radiated with LLL at a distance of 3cm for 1min. showed 99.8% higher antibacterial effect in comparison to the experimental group treated only with TBO. 3. The bacteriocidal effect of the P. gingivalis 2561 treated with TBO was found to gradually increase as the radiation time of LLL extended from 1min. to 3min. at 1min. intervals. 4. A slight decrease in bacteriocidal effect of the P. gingivalis 2561 was found as the radiation distance of LLL increased from 1cm to 3cm at 1cm intervals. 5. The bacteriocidal effect of the Pr. intermedia was found to slightly decrease as the radiation distance of LLL increased from 1cm to 3cm at 1cm. intervals. As the results shown above suggest, the bacteriocidal effect of LLL was found to increase as the radiation time extended and the distance shortened. Moreover, even the experimental group radiated with LLL at 3cm distance for 1min. which showed the lowest level of bacteriocidal effect, was found to have 99.8% higher bacteriocidal effect than the experimental group which was treated only with TBO and, therefore, this clearly shows the bacteriocidal effect of LLL against oral microorganisms. Thus, the use of LLL is thought to become very useful for suportive treatment for periodontitis and implantitis, and controlling oral malodors as long as it is used within the limits where there is no side effect.

• Journal of Oral Medicine and Pain
• /
• v.33 no.2
• /
• pp.159-166
• /
• 2008

An ideal anti-bacterial medication for oral infection requires selective effect on pathogens causing dental caries and periodontal disease but not on normal flora. In addition, it should be less toxic for human and even for environment. This study was to seek such a natural anti-bacterial medication and thus anti-bacterial effect of Hamamelis virginiana was evaluated. Many recent researches on the anti-bacterial effect of natural plant extract and essential oil have reported that natural products can be used as medication for prevention and restrainment of dental caries, halitosis and periodontitis. It has been also reported that Hamamelis virginiana has anti-bacterial effect on Porphyromonas gingivalis, Fusobacterium nucleatum, Capnocytophaga gingivalis, Veilonella parvula, Eikenella corrodens, Peprostreptococcus micros, and Actinomyces odontolyticus. This study evaluated anti-bacterial effect of Hamamelis virginiana on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae to expand its anti-bacterial effect on other important oral pathogens and eventually to develop its oral care products or apply to clinical purpose. In this study, anti-bacterial tests for antibiotic disk susceptibility, minimal inhibitory concentration and minimal bactericidal concentration were performed to evaluate anti-bacterial effect of Hamamelis virginiana against Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae. The results showed that Hamamelis virginiana has anti-bacterial effect on all pathogen strains tested in this study and furthermore Hamamelis virginiana possesses bactericidal effect other than bacteriostatic effect on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, Klebsiella pneumoniae. This study indicates that a natural anti-bacterial medication for oral diseases can be developed using Hamamelis virginiana.

• Journal of Periodontal and Implant Science
• /
• v.31 no.1
• /
• pp.1-23
• /
• 2001

Chitosan is biodegradable natural polymer that has been demonstrated its ability to improve wound healing, and calcium metaphosphate(CMP) is a unique class of phosphate minerals having a polymeric structure. In this study, chitosan/CMP and platelet derived growth factor(PDGF-BB) loaded chitosan/CMP sponges were developed, and the effect of the sponges on bone regeneration and their possibility as scaffolds for bone formation by three-dimensional osteoblast culture were examined. PDGF-BB loaded chitosan/CMP sponges were prepared by freeze-drying of a mixture of chitosan solution and CMP powder, and soaking in a PDGF-BB solution. Fabricated sponge retained its 3-dimensional porous structure with $100-200\;{\mu}m$ pores. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with $^{125}I-labeled$ PDGF-BB. In order to examine their possibility as scaffolds for bone formation, fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 28 days. Cell proliferation, alkaline phosphatase activity were measured at 1, 7, 14 and 28 days, and histologic examination was performed. In order to examine the effect on the healing of bone defect, the sponges were implanted into rat calvarial defects. Rats were sacrificed 2 and 4 weeks after implantation and histologic and histomorphometrical examination were performed. An effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. PDGF-BB loaded chitosan/CMP sponges supported the proliferation of seeded osteoblastic cells as well as their differentiation as indicated by high alkaline phosphatase activities. Histologic findings indicated that seeded osteoblastic cells well attached to sponge matrices and proliferated in a multi-layer fashion. In the experiments of implantation in rat calvarial defects, histologic and histomorphometric examination revealed that chitosan/CMP sponge promoted osseous healing as compared to controls. PDGF-BB loaded chitosan/CMP sponge further echanced bone regeneration. These results suggested that PDGF-BB loaded chitosan/CMP sponge was a feasable scaffolding material to grow osteoblast in a three-dimentional structure for transplantation into a site for bone regeneration.

• Journal of dental hygiene science
• /
• v.3 no.1
• /
• pp.23-31
• /
• 2003

In this research, dental health awareness of 3rd graders of high schools in Icheon-city was investigated in order to use the result of this research as the basic data for school dental health program, education direction, and educational purpose. The research was done from Sep. 23. to Oct. 5 and the followings are the results of survey. (1) 85.0% of the students brush their teeth once or twice a day and more female students brush their teeth 3 times a day than male students. (2) 77% of the students had experienced dental caries and 38.0% of the students have periodontal disease, which has lower percentage than cavity. (3) Most of the students can not go to the dentists because they do not have time and 84.0% of the students have been treated in dental clinics so this tells that most of the students had experienced dental treatment. (4) 46.8% of the students had interests in dental health and male students showed more interests than female students and the difference was statistically significant(p<0.05). (5) Most of the students hear the importance and information of dental health from mass media such as TV and radio or from people around. The research shows that most of the students do not get periodic dental checkups. (6) 80.8% of the students had never taught dental health education for improvement of dental health and 76.2% of the students think that the dental health education is needed. There was no difference according to the gender. (7) Most of the students think that the dental health education is needed to prevent cavity and gingiva disease and it shows that more students tend to attend the dental health education. (8) 69.3% of the students think that brushing your teeth is important to maintain good dental health and there was no difference according to the gender. Most of the students weren't aware that periodic dental checkups, right brushing, and using fluoric toothpaste is effective for cavity protection. (9) After looking into the knowledge of the students on dental health, it shows that the knowledge is low and there is no difference according to the gender.

• Journal of dental hygiene science
• /
• v.5 no.4
• /
• pp.245-250
• /
• 2005

This study was executed from June first to 30th. 2005. The target was first and second graders of Bok-Hyun elementary school and their mothers. The total of participants was 275 persons and the component ratio was 135 first graders and 140 second graders, also 82 boys and 193 girls. They answered to the question sheet by writing out with their own hands. Among the 300 question sheets that were answered, 275 sheets were analyzed, excepting 25 sheets that got poor answer. The results were as follows; (1) About the behavior of mothers and their children for oral health, In mothers' case, 68.8% of them answered that they brush teeth more than 3 times a day and 31.3% answered that they brush teeth less than 2 times a day, so those who brush teeth more than 3 times were more than those who brush teeth less than 2 times In children's case, on the contrary, 14.2% of them answered that they brush teeth more than 3 times a day and 85.8% answered that they brush teeth less than 2 times a day, so those who brush teeth less than 2 times were more. (2) In 7 questions for researching mothers' knowledge level about fluorine, 55.3% of them answer 3~4 questions correctly. In 7 questions for researching mothers' knowledge level about Periodontal disease, 47.3% of them answer 3~4 questions correctly and it was highest. (3) In a case of the relation between oral health knowledge and behavior of mother and frequency of brushing teeth of children, statistical similarity on frequency of brushing teeth was shown(p < 0.05). (4) In a case of the relation between social-anthropological features of mother and frequency of brushing teeth of children, there was no statistical similarity on age, mothers' educational level, monthly income. However, statistical similarity was shown about existence of mothers' occupation(p < 0.05).

• Journal of dental hygiene science
• /
• v.14 no.4
• /
• pp.468-476
• /
• 2014

The aim of this study was to examine whether there is an association between vitamin intakes and established periodontitis in Korean adult population. The 6,245 subjects aged over 19 years old, who participated in health survey, oral examination and nutrition survey were selected for this study from the database of the Fourth Korean National Health and Nutrition Examination Survey. Established periodontitis was defined as ${\geq}$ code 3 in community periodontal index. Vitamin intake was assessed with the food-frequency questionnaire. In analysis, participants were classified by quintile of vitamin intakes. We also considered covariates as socio-demographic characteristics, health-related behaviors including physical activities, systemic diseases and oral health-related behaviors. Multiple logistic regression was performed to assess the crude and adjusted associations. All analyses considered a complex sampling design using SAS 9.2. In crude analysis, less intake of vitamin A, retinol and vitamin B2 significantly increased the risk of periodontitis (vitamin A, odds ratio [OR] Q1=1.00, Q2=0.73, Q3=0.80, Q4=0.77, Q5=0.78; retinol, OR: Q1=1.00, Q2=0.86, Q3=0.73, Q4=0.62, Q5=0.55; vitamin B2, OR: Q1=1.00, Q2=0.70, Q3=0.63, Q4=0.67, Q5=0.68). However, after adjusting for socio-demographics, general and oral health status and behaviors, only vitamin B2 was significantly associated with established periodontitis (OR: Q1=1.00, Q2=0.72, Q3=0.73, Q4=0.76, Q5=0.84). An adequate vitamin B2 intake was significantly associated with a decreased risk of periodontitis. This finding shows that nutrient intake is slightly correlated with periodontitis in Korean adult population. Further studies are needed to understand this association between nutrients intake and periodontitis in more details.

• Journal of dental hygiene science
• /
• v.14 no.2
• /
• pp.150-157
• /
• 2014

The aim of this study was to suggest a convenient method of monitoring the gingival state through plaque detection. Quantitative Light-Induced Fluorescence-Digital (QLF-D), which can assess mature plaque, can be used to assess the oral hygiene status of individuals and to establish an adequate intervention plans for them. The subjects of the study participated in the clinical training at Department of Dental Hygiene, N University. The subjects completed questionnaires on general characteristics and oral hygiene methods. Then, photographs of maxillary and mandibular anterior teeth of the subjects were taken using the QLF-D. After the oral examinations, gingival state was recorded according to the $L{\ddot{o}}e$ & Silness's Gingival Index (GI). In addition, a plaque control record was calculated in percentage using disclosing agent. The analysis of the relation between the plaque control record and the QLF-D scores showed positive correlation (r=0.638, p<0.001), and the analysis of the relation between the QLF-D scores and the gingival bleeding index scores also showed positive correlation (r=0.562, p<0.001). Besides, the study classified the participants into healthy gingiva group and the gingivitis group according to the classification criteria of GI, and when the difference of QLF-D scores between the groups was analyzed, the QLF-D scores were statistically significantly higher (t=-2.785, p=0.007) in the gingivitis group ($1.71{\pm}1.545$) than the healthy gingiva group ($0.74{\pm}1.290$). When the differences in mean values of the QLF-D scores were analyzed against and the gingival bleeding index scores, the QLF-D scores of 0 and 1 belonged to the category of normal gingival state while the QLF-D scores of 2, 3 and 4 belonged to the category of gingivitis state. Therefore, it is deemed that the red fluorescence detected by the QLF-D from the mature supragingival plaque can be used for monitoring the state of gingivitis.