• Restorative Dentistry and Endodontics
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• v.48 no.2
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• pp.13.1-13.11
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• 2023

Objectives: Natural extracts have been investigated as a biomimetic strategy to mechanically strengthen the collagen network and control the biodegradation of extracellular matrix. This study evaluated the effect of epigallocatechin-3-gallate (EGCG) on abfraction lesions prior to the composite resin. Materials and Methods: The sample consisted of 30 patients (aged between 28 and 60 years) with abfraction lesions located in 2 homologous premolars. The teeth were randomly assigned according to dentin treatment: 0.02% EGCG solution or distilled water (control). After enamel acid etching, the solutions were applied immediately for 1 minute. The teeth were restored with Universal Adhesive (3M) and Filtek Z350 XT (3M). Analyzes were done by 2 independent examiners using modified USPHS (retention, secondary caries, marginal adaptation, and postoperative sensitivity) and photographic (color, marginal pigmentation, and anatomical form) criteria at baseline (7 days) and final (18 months). The data analysis used Friedman and Wilcoxon signed-rank tests (α = 0.05). Results: At baseline, all restorations were evaluated as alpha for all criteria. After 18 months, restorations were evaluated as alpha for secondary caries, color, and marginal pigmentation. There was significant difference between baseline and 18 months (p = 0.009) for marginal adaptation and postoperative sensitivity (p = 0.029), but no significant difference were verified between treatments (p = 0.433). The EGCG group had a restoration retention rate of 93.3%, while the control group had 96.7%. Conclusions: The application of EGCG solution on abfraction lesions did not significantly influence the survival of the restorations based on clinical and photographic criteria.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.32 no.2
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• pp.36-45
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• 2023

The aesthetic appearance of the incisors is essential for a natural and healthy smile, and it is also an important factor for confidence in interpersonal relationships. If there is crowding or protrusion of the anterior teeth, root canal treatment and excessive tooth removal are often required to resolve it in a short period of time. However, it is difficult to achieve sustainable aesthetic results. In this case, orthodontic treatment will be necessary to preserve the remaining tooth structure as much as possible. Middle-aged and elderly patients are often aware of the need for orthodontic treatment, but they are hesitant to use the traditional orthodontic treatment method using brackets because of the social gaze. In this case, clear aligners can be a good option. So, in this article, a case in which aesthetic needs were resolved with clear aligners alone and another case in which satisfactory results were obtained through restorative treatment following clear aligners application are reported.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.81-103
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• 1998

The purpose of this study was to compare and evaluate the differences in masticatory performance, muscle activity, and patterns of occlusal contact between persons with natural dentition and removable partial denture wearers. Twenty healthy adult subjects with more than 28 teeth and thirteen removable partial denture wearers that classified Kennedy classification I was selected. The degree of pulverized rice and peanut was measured and analyzed by means of sieving method to compare the masticatory performance. For the muscle activity, EMG was recorded in selected muscles(Temporalis and masseter muscle) during mastication and resting state. The occlusal record in maximal intercuspation was taken with a silicone occlusal bite registration material for analysis of the patterns of occlusal contact. The obtained results were as follows: 1. When chewed peanuts, masticatory performance ratio at 10-sieve size was 81.31% in natural dentition group. In removable partial denture wearer, 27.01% without RPD and 69.09% with RPD. When chewed rice, 42.04%, 11.87%, and 21.58%, respectively. The differences of masticatory performance ratio between groups were statistically significant at the 0.05 level. 2. The mean EMG value in resting state was $1.06{\mu}V$ on temporal muscle, $0.98{\mu}V$ on masseter muscle in natural dentition group. In removable partial denture wearers, $1.13{\mu}V$ on temporal muscle, $1.05{\mu}V$ on masseter muscle without RPD and $1.11{\mu}V$ on temporal muscle, $1.04{\mu}V$ on masseter muscle with RPD. 3. The mean EMG value during mastication was $45.64{\mu}V$ in natural dentition group, and in removable partial denture wearers, $22.06{\mu}V$ without RPD and $31.01{\mu}V$ with RPD when chewed peanuts. When chewed rice, $45.24{\mu}V,\;25.53{\mu}V\;and\;32.14{\mu}V$, respectively. The differences of mean masticatory EMG value between groups were statistically significant at the 0.05 level. 4. The number of posterior occlusal contact point was 20.15 in natural dentition group and 11.92 in removable partial denture wearers. The area of perforated surface was $16.50mm^2$ in natural dentition group and $6.06mm^2$ in removable partial denture wearers. The area of contact surface was $78.93mm^2,\;51.52mm^2$, respectively. 5. The area of contact surface was effective to masticatory performance ratio in natural dentition group and removable partial denture wearers (p<0.05). From these results, it is concluded that in partially edentulous patient, masticatory efficiency can be improved by removable partial denture wearing, and for efficient mastication, tight occlusal contact surface shoud be maintained by maximum support that is provided from mucosa.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.157-162
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• 2005

To clarify the key characteristics of Korean brown frogs (R. dybowskii, R. huanrenesis and R. amurensis coreana), this study employed a morphological and morphometrical comparisons among brown frogs found in Korea and Japanese endemic species, R. tsushimensis. As a result, it was considered that the key characteristics were the shape of the finger and toe tips, the markings of the lower jaw, the presence or absence of an upper lip line, the development of toe webbing, and the shape of the vomerine teeth series by morphological comparisons of brown frogs. Also, there were significant differences in tympanum diameters and foot lengths of the four species of brown frogs. Therefore, a comparison between morphological and morphometric characters is an effective way to clarify the identification of brown frogs.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.337-345
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• 2007

Changes of feeding habitat and feeding organ of a land-locked sweetfish, Plecoglossus altivelis related to their growth process were investigated in the Lake Okjeong, Sannae-myeon, Jeongeup-si, Jeollabuk-do, Korea from 2004 to 2005. In the lake, the post-larvae from 25 to 40 mm in standard length fed mainly on animal organisms such as Copepoda, Branchiopoda and Rotatoria. Also, the juveniles from 50 to 60 mm (SL) fed on Chironomidae of Diptera, Copepoda and Branchiopoda. However, the juvenile from 60 to 70 mm (SL) in the Churyeong Stream fed on animal organisms and aquatic algae, the immature fishes more than 70 mm (SL) fed on only periphyton such as Synedra, Cymbella, Navicula and Pinnularia. Also, the feeding organs of the tooth and stomach were changed according to its growth and food change.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.399-406
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• 2013

Reports about the intrusion of a natural tooth bounded by implants are very rare, although some concerns have been discussed on the intrusion of teeth connected to implants. A female aged 56 years received an implant (mandibular right first premolar) and post/core onto root rest (mandibular right second premolar) and was restored by single zirconia crown, respectively. Molars were implant restorations. Four month after loading, second premolar was intruded and prominent gap was shown between opposite tooth. Because nonspecific discomfort was expressed, observation was decided after explanation of prognosis of tooth without treatment. Three month later reversal to original position was detected on the periapical radiographs and fully recovered position with intimate contact was completed 11 more months later. Till now 2 years and 3 month observation is being performed. Through the observation of spontaneous recovery of a natural tooth bounded by implants, the cause of intrusion and a mechanism of spontaneous recovery could be estimated.

• Journal of Korean Dental Science
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• v.16 no.2
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• pp.192-203
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• 2023

Purpose: This study is to investigate the distribution of natural tooth shades in the Korean elderly population to quantify the correlation and changes of tooth color with age and gender. In addition, the possible effects of habits on tooth color were assessed. Materials and Methods: The tooth color of one of the maxillary central incisors of 200 Korean individuals aged 50 to 89 years, males and female, was measured using the portable intraoral spectrophotometer (VITA Easyshade V). CIELab and CIELCh color coordinates were recorded. We conducted the survey about the tobacco smoking, chronic disease, medication, eating habits, oral health behaviors and satisfaction with tooth color. Experimental data were statistically analyzed by using the t-test (P<0.05), two-way analysis of variance and Pearson's correlation test. Result: The most frequent color in the Korean elderly population was 3M3 & A3.5 shade. L^* and h^* values decreased, whereas C^*, a^* and b^* values increased progressively with age. There was a significant interaction between age and color coordinates for b^* values (r=0.245, P<0.05). Males generally have significantly higher C^*, a^*, b^* values and lower L^*, h^* value compared to females. Individuals who consumed alcohol had a higher L^* value (P<0.05). Conclusion: Within the limitation of this study, the central incisors were getting darker, more reddish, and yellowish with age. Information on the chromatic range of natural teeth by age and gender could help to select colors for esthetic dental restorations.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.475-483
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• 2009

Subjects of the research were 668 elderly people aged over 65 from Gangneung city. OHIP 14 went through a first translation from English to Korean, discussion among experts, a second translation from Korean to English, and then the translation was approved. After the primary and main research were carried out, validity and correlation coefficient with the outcome of oral and mental health examination were studied. OHIP 14 in terms of the perception of oral health was relevant to the perception of overall health and oral health, the necessity of dental treatment, the satisfaction about oral health, the level of pain from observation, and the satisfaction about artificial tooth. OHIP 14 on account of oral health state was related to the number of present natural teeth, the necessity of dental treatment, and the status of no teeth. OHIP 14 according to overall health was correlated to the number of ailments, the state of mind, nerve systems, bones and sinews, digestive systems, urogenital systems, cerebrovascular systems, respiratory systems, eyes, ears, and dementia. OHIP 14 according to the perception of oral health showed a significant difference in the perception of overall health and oral health, the level of pain in terms of observation, and the satisfaction on artificial tooth. OHIP 14 on account of oral health state demonstrated a meaningful difference in the number of present natural teeth, the necessity of dental treatment, and status of no teeth. OHIP 14 in terms of overall health exhibited considerable difference in the state of mind, nerve systems, bones and sinews, digestive systems, cerebrovascular systems, respiratory systems, ears, and dementia. From the study, it was proven that there was relevance between the validity of OHIP 14 and the perception of oral health, the state of oral health, and the state of overall health in the experiment on some Korean elderly people.

• The Journal of the Korean dental association
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• v.47 no.10
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• pp.669-676
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• 2009

Purpose : Anterior region is crucial area for esthetic implant restoration. However, the alveolar process undergoes atrophy after removal of teeth and creates unfavorable situation for implant installation. The knowledge of the thickness of alveolar bone is required to estimate and expect the bone resorption after extraction. The aim of this study is to measure facial, palatal and faciopalatal bone thickness on maxillary anterior teeth. Methods : Facial, palatal, and faciopalatal bone thickness were measured on the computed tomography (CT) images from 57 patients, using an image analyzer program (Ondemand$3D^{(R)}$, Cybermed, Seoul, Korea). Results : The thickness of facial bone in incisors, lateral incisors and canines were less than 1 mm. The thickness of facial bone increased from anterior to posterior region and the thickness of palatal bone increased from posterior to anterior region. Conclusion : The measurement can be used for planning implant surgery before extraction. CT has are clinically useful in the evaluation of thickness of alveolar bone.

• Korean Journal of Ichthyology
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• v.1 no.1_2
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• pp.83-92
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• 1989

The pharyngeal teeth and the masticatory process of the basioccipital bone were compared in ten species of Korean bitterlings. Three species, Acheilognathus lanceolata, A. limbatus, A. signifier and Rhodeus ocellatus, which are characterized by the absence of serrations on the side of the pharyngeal teeth, are found to, have reduced occlusal grooves on the outside of occlusal margin, Among Korean bitterlings, differences are found in the developmental degrees of the anterior part of the masticatory process, the grooves on the occlusal surface and the chewing area on the pharyngeal first tooth. The occlusal grooves in herbivorous species are considered to be more developed than those in omnivorous species. Considering these findings, the combination of developmental degrees in the three pharyngeal elements suggests generally the phylogenetic relationships among the Korean bitterlings.