• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5109-5115
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• 2014

The aim of this study was to develop a standard toothbrush to determine the changes the dental arch form. Toothbrushes were collected from university students Items, such as the toothbrush head size, shape of head, numbers of tuft, neck size, neck angle, and handle size, were measured. the full mouth study models from the participants were In conclusion, the size of the head of the toothbrush for adults needs to be less than the 25mm and less than 11mm in the longitudinal and transverse directions, respectively. The choice of toothbrush is important for controlling oral hygiene and professional education on the selection of the appropriate toothbrush is needed.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.906-914
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• 1996

Due to the various reason, sealing of pit & fissure might be imperfect. One of these reason can be the fracture of sealant material because of the low hardness value of sealing material. The purpose of this in vitro study was to evaluate the microhardness of two different curing type pit and fissure sealants: Dual-cure and Light-cure. The result from the present study can be summarized as follows: 1. All pit and fissure sealants that used in this study showed statistically significant difference in their microhardness of upper and lower surface. (P <0.05) 2. Except of lower surface of teethmate, microhardness of 40-second curing sealant was statistically higher than that of 20-second curing sealant. (P <0.05) 3. In comparison of sealants, microhardness of dual-cure sealant was statistically higher than that of light-cure sealant. Above results suggest that the use of dual-cure sealant and longer curing time are recommended.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.199-205
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• 2000

The vibration and noise of gears is due to the vibration exciting force caused by the tooth stiffness which changes periodically as the mesh of teeth proceeds and by the transmission error, that is, the rotation delay between driving gear and driven gear caused by manufacturing error and alignment error in assembly and so on. The purpose of this study is to develop how to calculate simultaneously the optimum amounts of tooth profile modification, end relief and crowning by minimizing the vibration exciting force of helical gears. We estimate the vibration exciting force by the mesh analysis of gears. The constraints of this problem consist of contact ratio and strengths of gear teeth such as tooth fillet stress, surface durability and scoring. ADS(Automated Design Synthesis) is used as an optimization tool. And, since the aspect ratio is an important parameter of tooth modification, we investigate the relation between it and the optimum values of tooth modification. The proposed method can calculate the optimum amount of tooth modification automatically and is to be utilized to resolve the problem of vibration of helical gears.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.4
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• pp.484-489
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• 2021

Black staining of the teeth in children and adolescents does not cause pain or serious illness, but it can be socially debilitating for esthetic reasons. Black staining is easily removed through periodic professional mechanical tooth cleaning and ultrasonic scaling, but it can easily recur within few months. Using essential oil-containing mouth rinses diluted at 50% twice per day could prevent the black staining from returning after it is removed, reducing the need for mechanical treatments and improving esthetics.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.535-543
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• 2008

Purpose: The objective of this study was to compare the bonding characteristics of a new self-adhesive resin cement to dentin, which does not require bonding and conditioning procedure of the tooth surface, and conventional resin cement. The effect of phosphoric acid etching prior to application of self-adhesive resin cement on the shear bond strength was also evaluated. Material and methods: Fortyfive non-carious human adult molars extracted within 6 months were embedded in chemically cured acrylic resin. The teeth were ground with a series of SiC-papers ending with 800 grit until the flat dentin surfaces of the teeth were exposed. The teeth were randomly divided into 3 experimental groups. In group 1, self-adhesive resin cement, RelyX Unicem (3M ESPE, Seefeld, Germany) was bonded without any conditioning of teeth. In group 2, RelyX Unicem was bonded to teeth after phosphoric acid etching. For group 3, Syntac Primer (Ivoclar Vivadent AG, Schaan, Liechtenstein) was applied to the teeth before Syntac adhesive (Ivoclar Vivadent AG, Schaan, Liechtenstein) and Helibond (Ivoclar Vivadent AG, Schaan, Liechtenstein) followed by conventional resin cement, Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein). To make a shear bond strength test model, a plastic tuble (3 mm diameter, 3 mm height) was applied to the dentin surfaces at a right angle and filled it with respective resin cement, and light-polymerized for 40 seconds. All the specimens were stored in distilled water at $37^{\circ}C$ for 24 hours before test. Universal Testing Machine (Z020, Zwick, Ulm, Germany) at a cross head speed of 1 mm/min was used to evaluate the shear bond strength. The failure sites were inspected under a magnifier and Scanning Electron Microscope. The data was analyzed with One way ANOVA and Scheffe test at ${\alpha}$= 0.05. Results: (1) The shear bond strengths to dentin of RelyX Unicem was not significantly different from those of Variolink II/Syntac. (2) Phosphoric acid etching lowered the shear bond strength of RelyX Unicem significantly. (3) Most of RelyX Unicem and Variolink II showed mixed fractures, while all the specimens of RelyX Unicem with phosphoric acid etching demonstrated adhesive failure between dentin and resin cement. Conclusion: Shear bond strength to dentin of self-adhesive resin cement is not significantly different from conventional resin cement, and phosphoric acid etching decrease the shear bond strength to dentin of self-adhesive resin cement.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.465-472
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• 2010

This study surveyed salivary flow rate, salivary viscosity, and salivary buffering capacity in order to intensively analyze salivary factors among factors of occurrence in dental caries for finding mutually different factors that function in occurrence of dental caries depending on each individual. Even the acid body within dental plaque has great influence upon dental caries. Thus, the comparative analysis was carried out by surveying the hydrogen ion concentration in dental plaque. The following results were obtained in this study. 1. The average decayed teeth in the survey subjects stood at 1.67 piece. The extracted teeth caused by dental caries stood at 0.47 piece. The filled teeth were indicated to be 6.31 pieces. Accordingly, the average permanent dental caries experience teeth were surveyed to be 8.44 pieces. 2. The results according to dental caries activity test method were indicated to be $12.56{\pm}4.15ml$ for the average stimulated salivary flow rate, $3.89{\pm}1.83ml$ for non-stimulated salivary flow rate, $1.49{\pm}0.69$ for salivary viscosity, and $8.51{\pm}2.44$ for salivary buffering capacity. The hydrogen ion concentration test in dental plaque was indicated to be $5.62{\pm}0.50$ for before brushing teeth, $5.23{\pm}0.58$ for 5 minutes after brushing teeth, $5.25{\pm}0.56$ for 10 minutes after brushing teeth, $5.29{\pm}0.62$ for 15 minutes after brushing teeth, $5.34{\pm}0.58$ for 20 minutes after brushing teeth, $5.40{\pm}0.53$ for 25 minutes after brushing teeth, and $5.61{\pm}0.59$ for 30 minutes after brushing teeth. 3. Stimulated salivary and non-stimulated salivary flow rate, salivary viscosity, and salivary buffering capacity were indicated to be higher in group with non-caries than group with caries. However, it was statistically insignificant. The hydrogen ion concentration in dental plaque showed wholly statistical significant in the relationship with people with dental caries under progression. However, people without dental caries were indicated to be higher than people with dental caries. 4. As for correlation between caries activity test methods, the stimulated salivary flow rate had significantly positive correlation with non-stimulated salivary flow rate(p<0.001). Non-stimulated salivary flow rate showed negative correlation with salivary buffering capacity(p<0.01). The hydrogen ion concentration test in dental plaque showed positive correlation according to the passage of time after brushing teeth. However, there was no significant correlation with salivary viscosity and salivary buffering capacity(p>0.05).

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.1-8
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• 2022

Purpose: The purpose of this study was to evaluate the effects of mouthwash containing sodium chloride on dental plaque, gingival inflammation index, and bad breath through clinical trials. Materials and Methods: This trial was designed as 12 weeks and subjects were instructed to put an appropriate amount of the provided standard detergent on a toothbrush and brush their teeth 3 times a day. They were instructed to gargle a mouthwash provided to each group after brushiung. Efficacy was evaluated by performing gingival and periodontal-related index tests, dental plaque changes, and bad breath tests a total of 5 times. All data were statistically analyzed using 2-sample t-test, paired t-test to compare between groups at 95% significance level using IBM SPSS Statistics 24.0. Results: As a result of the PMA index measurement, the gingivitis improvement effect rate of the experimental group compared to the control group was 107.63% after 8 weeks and 73.08% after 12 weeks. As a result of the PHP index measurement, the plaque improvement effect rate of the experimental group compared to the control group was 79.37% after 8 weeks and 74.06% after 12 weeks. As a result of measuring volatile sulfur compounds using Oral Chroma, the effectiveness of improvement in bad breath in the experimental group was 65.06% after 8 weeks and 99.33% after 12 weeks, compared to the control group. Conclusion: As a result of this study, it was confirmed that effective gingivitis alleviation, plaque removal effect and bad breath removal effect can be expected when a mouthwash containing sodium chloride, green tea extract, and sodium monofluorophosphate is used.

• Journal of dental hygiene science
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• v.16 no.6
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• pp.432-441
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• 2016

This study was conducted to investigate the effects of professional oral healthcare program in eldery residents long-term care facilities. Ninety-four elderly residents from 5 different facilities in Asan participated in this study. The subjects were divided into 3 groups, with 32 in experimental group I, 30 in experimental group II, and 32 in the control group. Subjects in experimental group I were treated by a dental hygienist with professional oral healthcare and received daily oral care from caregivers who had completed elderly oral healthcare course. Subjects in experimental group II received daily oral care from caregivers who had completed elderly oral healthcare course. Control group received daily oral care from caregivers. These 3 groups were tested for dental plaque, halitosis, tongue coating, and salivary flow at baseline, and after 4 and 12 weeks of treatment. There were significant differences in the dental plaque index between the groups, mediate times, and mediate methods, in halitosis between the mediate methods, and in tongue coating between the mediate times, as well as the mediate methods. Finally, salivary flow was significantly different with regard to mediate methods between experimental group II and the control group. Therefore, to improve the oral health condition of elderly residents, involvement of a part-time dentist and scheduled professional oral healthcare are necessary. Furthermore, elderly oral healthcare education for nursing staff, including managers, should be provided.

• The korean journal of orthodontics
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• v.38 no.6
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• pp.407-415
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• 2008

Objective: The aim of this study was to evaluate the remineralization of interdentally stripped teeth after fluoride gel or hydroxyapatite paste application. Methods: After interdental stripping, 1.23% fluoride gel or 10% hydroxyapatite paste was applied three times a day, with a duration of four minutes, for a week. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to compare the change of surface contents and crystal structures before and after the application of fluoride gel or hydroxyapatite paste. Results: EDS analysis indicated that calcium contents were increased after 10% HAp paste application on stripped enamel (p < 0.01). SEM view showed that enamel surfaces in groups of 1.23% APF gel or 10% HAp paste application were smoother than those of control group, which was regarded as filling of the pore structure. And pores between crystal structures in groups treated with 1.23%, APF gel or 10% HAp paste were smaller than those of control group. Conclusions: Application of APF or HAp on stripped enamel could positively influence on the surface contents or crystal structure.

• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.209-216
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• 2010

The purpose of this study was analyzing the first permanent molars condition that was how catch on general oral health of the children in primary school, to make use of the basic data on dental health policy project for the school oral health. The sampling was done at the primary school in Suncheon. It made a survey on the first permanent molars of 823 person who had attended in March, 2009. By using the WHO standards and Clune's dental health capacity, the conditions of first permanent molars calculated. DMFT index and it's condition of first molars statistically are analyzed by Pearson's correlation. 1. The dental health capacity of the first permanent molars was 92.2%. 2. The DMFS index of first permanent molars was 3.97. 3. The dental health capacity of first permanent molars have related with DMFT index(r= -0.895). 4. DMFS index of the first molars have positive relation with DMFT index(r= 0.902). In this repory, I would like to suggest that the evaluation of dental health project for the school aged children should be considered including the healthy status of the first molars.