• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.415-423
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• 1991

This study was performed to evaluate the geometric standardization of periapical intraoral radiography. Image distortion was measured by analysing serial radiography obtained from dry skull using 5 types of bite registration device. After 16 weeks, the angular distortion of Pattern resin was 0.26±0.14 degree(Horizontal angle 0.17±0.14, Vertical angle 0.16±0.11) which was the lowest among the 5 registration device, and that of putty type Exaflex was 0.49±0.35 degree(Horizontal angle 0.42±0.35, Vertical angle 0.17±0.13) which was the highest. The mean amount of distortion variance of Tooth shade acrylic at each experimental period was 0.06±0.08 which was the lowest among the 5 registration device, and that of XCP alone was 0.ll±0.13 which was the highest.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.570-577
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• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• The korean journal of orthodontics
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• v.23 no.3 s.42
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• pp.375-389
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• 1993

The delivery of optimal orthodontic treatment is greatly influenced by a clinician's ability to predict and control tooth movement achieved by applying known force systems to the dentition. It is important to determine the location of the center of resistance of a tooth or group of teeth to better understand the nature of their displacement characteristics under the various force levels. The purpose of this study was to define the location of the centers of resistance of various units of the upper anterior segment for lingually directed 100gm and 200gm force in a dry human skull. The units investigated were composed of four incisors and six anterior teeth. In addition, the effect of change in force magnitude on the location of the center of resistance of these units was investigated. The laser reflection technique was used to measure the initial displacements of the consolidated teeth under loading. The results were as follows: 1. The instantaneous center of resistance for the four anterior teeth was located vertically between level 4 and level 5-that is, at $37.4\%$ apical to the cementoenamel junction level. 2. The instantaneous center of resistance for the six anterior teeth was located vertically just beneath level 5-that is, at $50.3\%$ apical to the cementoenamel junction level. 3. Increasing force levels had little effect on the location of the center of resistance of a given unit. 4. The location of the instantaneous center of resistance shifted apically as the number of dental units consolidated increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.109-115
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• 2013

This study targeted 501 the elderly ages 65 or over in three places including the Senior Welfare Center and the college for seniors located in Daegu City and Gyeongsangbuk-do. The study results on the preference for oral health care management items across different ages showed that the age group of 65~69 fluoride application; the age group of 65~74 scaling and education of brushing; the age group of 70~74 denture cleaning and maintenance; the age group of 75 denture production. In the relationship between the self-perceived oral condition and the items of oral health care management, respondents who currently have a poor oral condition or have greater chewing trouble, or have higher dry mouth, preference the manufacturing of dentures in most cases. Respondents who have a lower number of teeth or wear dentures preference dentures cleansing and management in most cases. Respondents who have shaking teeth or have frequent tooth pain preference tooth extraction. Since the preference for oral health care management items may differ by their age or oral condition, oral health management customized to each individual should be applied.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.607-618
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• 2008

This study three-dimensionally and histologically assessed the effect of Emdogain$^{(R)}$ on periodontal healing in replanted teeth in three beagle dogs which were 1 to 2 years old, weighing from 10 to 13 ㎏. Twelve maxillary and mandibular incisors were intentionally extracted and replanted after 15(Group I), 30(Group II) and 60(Group III) minutes of air dry storage with and without the application of Emdogain$^{(R)}$. The following conclusions could be drawn from the present investigation. 1. Increased incidence of inflammatory healing response in periodontal tissue was proportional to air dry time in Both control and experimental group(P<0.001). 2. Treatment Group showed lower inflammatory root resorption, especially there were statically significant in Group I, III(P<0.001, Group II : P=0.093). 3. Inflammatory root resorption were mainly occurred in apical third(14, 15-16 section)(P<0.05, 0.001), and cervical third(1 section)(P<0.05). 4. In view of horizontal section of long tooth axis, Main root resorption area were 1, 4, 5 line area(bucco-lingual area)(p<0.01).

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.232-239
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• 2017

Objectives: The evaluation of iatrogenic dentinal defects in extracted teeth may be influenced by extraction forces and prolonged dry times. The purpose of this study was to compare the presence of dentinal defects in freshly extracted, periodontally compromised teeth with those in a group of teeth with uncontrolled extraction forces and storage time. Materials and Methods: The experimental group consisted of eighteen roots obtained from teeth extracted due to periodontal reasons with class II or III mobility. They were kept in saline and sectioned within 1 hour following extraction. The control group consisted of matched root types obtained from an anonymous tooth collection, consistent with previous dentinal defect studies. The slices were obtained at 3, 6, and 9 mm from the apex. The imaging process exposed all specimens to no more than 60 seconds of dry time. The ${\times}12.8$ magnification was used for the 9 mm slices and ${\times}19.2$ magnification for the 3 mm and 6 mm slices under light-emitting diode (LED) transillumination. The root canal spaces and periodontal tissues were masked to minimize extraneous factors that might influence the evaluators. Chi-square test was used for statistical analysis. Results: Dentinal defects were detected in 17% of the experimental group teeth, compared to 61% of control teeth (p = 0.015). Conclusions: LED transillumination assessment of freshly extracted roots with class II or III mobility showed smaller number of dentinal defects than roots with uncontrolled storage time and extraction forces. The use of freshly extracted roots with mobility should be considered for future dental defect assessment studies.

• Journal of Korean Medicine for Obesity Research
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• v.21 no.1
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• pp.32-41
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• 2021

Objectives: We aim to observe the relation of body mass index (BMI) and the indicators of oral health. Methods: 400 subjects participated in the study. The BMI values are calculated from the height and weight. For the tongue diagnosis, we used the tongue imaging device to analyze the color, tongue coating, and tooth marks. We measured the concentration of hydrogen sulfide (H₂S) and methyl mercaptan (CH₃SH) to evaluate the halitosis. The dry mouth was evaluated through the measurement of saliva secretion and with the questionnaire asking the frequency of dry mouth. Results: The BMI values were significantly higher in the group with light-white and blue-purple colored tongue, and significantly lower for lightly-coated tongue. However, the correlation of BMI and the amounts of saliva secretion was not significant as well as in the correlation of BMI and the concentration of H₂S, CH₃SH. In tongue diagnosis, the subjects who had blue-purple colored tongue also had significantly higher H₂S and CH₃SH, but tendency of lower saliva secretion. Conclusion: We obtain data showing that BMI value and the indicators of oral health including tongue diagnosis have meaningful correlation.

• The Journal of Advanced Prosthodontics
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• v.15 no.6
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• pp.315-332
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• 2023

PURPOSE. This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis. MATERIALS AND METHODS. This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05. RESULTS. The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16). CONCLUSION. The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.375-380
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• 2009

The purpose of this study was to help improve oral health care planning for the elderly in an effort to promote the oral health of elderly people in preparation for aging society. The subjects in this study were 200 elderly people who were selected by random sampling from senior centers in Seoul. An interview was conducted to gather data from June to September 2008, and the data collected were analyzed.: 1. The mean number of residual tooth was 13.71. 2. Concerning connections between gender and subjective oral symptoms, gender had a statistically significant relationship to temporomandibular joint dysfunction(p=0.000), dry mouth(p=0.001) and halitosis(p=0.006). The men underwent more oral symptoms than the women. 3. As for the relationship of mastication(p=0.000), oral pain(p=0.010), temporomandibular joint dysfunction(p=0.010) and dry mouth(p=0.001) to subjective oral health state, the elderly people who were not in a good oral health suffered more oral symptoms, and the gap between them and the others was statistically significant. 4. A larger number of tooth led to less mastication difficulties, less dry mouth and more gingival diseases, and the relationship between the factors was statistically significant. A better oral health state led to less mastication difficulties, less oral pain, less dry mouth and less bad breath, and the relationship between the factors was statistically significant. Through this study the oral health the elderly people perceive wss concerned with oral symptom, and the number of residual teeth also had links to subjective oral symptoms. Therefore, to maintain original teeth of the elderly people, the management system of oral health and the education program for oral health in order to prevent disease relateded with oral and enhance the perception standard of oral state are indispensably necessary to the elderly people.

• Restorative Dentistry and Endodontics
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• v.37 no.3
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• pp.155-159
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• 2012

Objectives: To investigate the effect of dentin moisture degree and air-drying time on dentin-bond strength of two different one-step self-etching adhesive systems. Materials and Methods: Twenty-four human third molars were used for microtensile bond strength testing of G-Bond and Clearfil $S^3$ Bond. The dentin surface was either blot-dried or air-dried before applying these adhesive agents. After application of the adhesive agent, three different air drying times were evaluated: 1, 5, and 10 sec. Composite resin was build up to 4 mm thickness and light cured for 40 sec with 2 separate layers. Then the tooth was sectioned and trimmed to measure the microtensile bond strength using a universal testing machine. The measured bond strengths were analyzed with three-way ANOVA and regression analysis was done (p = 0.05). Results: All three factors, materials, dentin wetness and air drying time, showed significant effect on the microtensile bond strength. Clearfil $S^3$ Bond, dry dentin surface and 10 sec air drying time showed higher bond strength. Conclusions: Within the limitation of this experiment, air drying time after the application of the one-step self-etching adhesive agent was the most significant factor affecting the bond strength, followed by the material difference and dentin moisture before applying the adhesive agent.