• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.380-393
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• 2004

The Purpose of this study was to investigate the dentoalveolar compensation according to anteroposterior skeletal discrepancy in normal occlusion and to evaluate cephalometric parameters that quantitatively describe dental compensations. The study consisted of 90 subjects (50 males. 40 females) who were selected among specimens of normal occlusion at Seoul National, University Dental Hospital, Dept. of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized for each subject. According to the anteroposterior skeletal pattern the sample was divided into three groups. Cephalometric data were analyzed for the three groups using the SPSS program. Independent t-test, correlation analysis and regression analysis were carried out. The results were as fellows: Dentoalveolar compensation was found in upper and lower incisor inclination and occlusal plane inclination. As the mandible located anterior to the maxilla, the maxillary incisors incisors more labially. the mandibular incisors more lingually, and the occlusal plane continued to flatten. The dental parameters most correlated with anteroposterior skeletal discrepancy were L1 to SN and L1 to FH. Among the compensatory dentoalveolar changes, lower incisor inclination was strongly related to the anteroposterior jaw relationship and played au imposrtant role in obtaining a normal incisor relationship U1 to PtGn and L1 to APog were constant irrelevant to anteroposterior skeletal discrepancy.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.194-200
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• 2016

PURPOSE. The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS. 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS. Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17-73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries. CONCLUSION. Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns.

• Phonetics and Speech Sciences
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• v.3 no.4
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• pp.33-43
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• 2011

The present study investigates supralaryngeal articulatory characteristics of denti-alveolar (coronal) stops /t, $t^h$, $t^*$/ and /n/ in /aCa/ context in Seoul Korean. An Electromagnetic Articulograph (EMA, Carstens) was used to explore kinematics of the consonants by examining the kinematic data of the tongue tip (the primary articulator for the coronal consonants), along with some additional supplementary position data of the tongue body, the tongue dorsum and the jaw. The results showed that the constriction duration was the most robust articulatory correlates of the three-way stop contrast with a pattern of /t/$t^h$/$t^*$/. The contrast was further reinforced by the tongue body position (higher for /$t^h$, $t^*$/) and the tongue tip opening displacement (less displaced for /$t^h$, $t^*$/). The articulation of /n/ was quite similar to that of the lenis /t/ in terms of the constriction duration, and it was different from the oral stops in that it was produced with larger tongue tip displacement and lower jaw position than the oral stops, indicating its weak articulatory nature. The results are also discussed in comparison with those of bilabial stops with implications that the three-way contrast may be kinematically expressed differently depending on the physiological constraints imposed on the primary articulator (the tongue tip versus the lips). The present study, therefore, provides new articulatory (kinematic) data of denti-alveolar consonants in Korean, and demonstrates that the three-way stops, that have been known to differ primarily in their laryngeal settings, are indeed produced with kinematic distinctions at the supralaryngeal level.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.2
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• pp.141-148
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• 2008

To prevent musculoskeletal disorders(MSD) for dental hygiene students, who will potentially be at high risk of developing MSD while performing oral prophylaxis practice, an MSD prevention education program was designed and was offered to a group of dental hygiene students to find whether the program is effective. Before the program started and three months after the program ended, changes in the students' posture were filmed to observe them. The final subjects for analysis included 30 students in the experimental group and 41 students in the control group. To verify differences between the experimental and the control groups, repeated measures ANOVA was carried out before and after the program. After the education program, the experimental group's RULA scores for neck, left upper arm, right forearm, and wrist, RULA A score on both left and right side, RULA B score on left side, and total RULA score were significantly lowered during the operation on the upper jaw, compared with that of the control group. And, during the operation on the lower jaw, the experimental group's RULA A score, RULA B score, and total RULA score were very significantly lowered. The results of this study suggest the MSD prevention education program is effective in preventing the disorder. Thus, the program can be utilized as an education program for preventing MSDs during dental hygiene students' oral prophylaxis practice and clinical practice.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.428-436
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• 2008

For Longevity of implant, considerations of biomechanical and microbiological aspects must be done. Recently, due to the remarkable development of bone grafting procedure. Implant has been implanted into the more favorable sites but peri-implantitis resulted from periodontal bacteria may obscure the long-term prognosis. Although many different modalities have been introduced to treat the failed implant. Implant's surface and irreversible bony destruction around the implant prevents good result. After Er,Cr:YSGG (waterlase) laser using the wave-length of 2780nm has been introduced to dental field, good results have been reported. Because waterlase uses the hydrokinetic force of water. It is excellent device to detoxify the implant surface mechanically without the heat generation and damage to the implant surface. We designed to evaluate waterlase effect on the peri-implantitis has been occurred after implantation. Four beagle dogs were involved. We have made four premolar extraction in each right and left side of the lower jaw and placed two implants in the anterior of the jaw as a control and six implant were placed posterior in each socket after extraction immediately as an experimental group. We tied floss-silk in each implant to make peri-implantitis intentionally. After three months, we explored peri-implant sites on each experimental fixtures. Using waterlase laser irradiation was performed on that implantitis sites under 3W, air 30% and water 20% intensity for 2 minutes. In control group, we repositioned the flap to cover the exposed fixture without any supportive care. Three months later, we sacrificed experimental animals and extracted and preparated bone blocks with Donath and Breuner (982), Donath (988)'s methods and examined under microscope. We have obtained good re-osseointegration around fixtures after treating with waterlaser irradiation. But it was shown fibroosseointegration in the control group.

• Journal of Korean Dental Science
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• v.7 no.1
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• pp.16-24
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• 2014

Purpose: This study was planned to clarify a negative view of chewing gum due to the concern that continuous gum chewing might cause a change in the gonial angle and make the lower facial appearance look square. Materials and Methods: We had 25 adults (13 males and 12 females, with an average of 27.3 years) chew 6 g of gum (spearmint) evenly with both right and left posterior teeth for one hour per day for three months. We then measured their gonial angle, the inclination of occlusal plane, facial height, bone marrow density, and masticatory force before chewing, 1, 2, and 3 month after chewing to verify its significance statistically. Result: The results showed that the gonial angle increased from $122.7^{\circ}$ to $123.3^{\circ}$ (P>0.05), and thus the jaws became slightly slimmer. There was no change in the occlusal plane inclination and facial height. Meanwhile bone marrow density in the mandibular angle and ascending ramus increased from $0.285g/cm^2$ to $0.290g/cm^2$ (P<0.05), and masticatory force also increased by 0.5 kg on the right side and 0.8 kg on the left side (P<0.05). Conclusion: Continuous chewing of gum gives an appropriate exercise effect to the stomatognathic system. As chewing gum has effect on increase bone marrow density without changing the mandibular angle and facial appearance the claim that jaw bone changes to a square jaw through chewing gum is regarded to be groundless.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.242-245
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• 2011

This is the first report of Japonolaeops dentatus Amaoka, belonging to the family Bothidae, collected in Korea. Four specimens (152.9~174.7 mm in standard length) were caught in the coastal waters of Jeju Island by using the bottom trawl. This species was characterized by the following morphological traits: 115~120 dorsal fin rays, 96~98 anal fin rays, 105~106 pores in lateral line, upper jaw extending to below anterior margin of lower eye, and teeth presenting on both ocular and blind sides of the jaw. We propose a new Korean name, "Geom-eun-kko-ri-neop-chi-sok" and "Geom-eun-kko-ri-neop-chi" for the genus and species, respectively.

• Development and Reproduction
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• v.20 no.2
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• pp.65-79
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• 2016

We observed the osteological development of larval and juvenile red spotted grouper (Epinephelus akaara) in order to generate data for the assessment of skeletal deformities and to inform phylogenetic systematics research. Larvae and juveniles were obtained from a aquafarm in Muan-gun, Jeolla-namdo Province, Korea. The average water temperature at the time of breeding was $23.0^{\circ}C$ and average water salinity was 33.0 psu. Freshly hatched fish larvae had not undergone any ossification, but ossification of the parasphenoid bone, which forms the base of the cranium, occurred as the juveniles reached an average body length (BL) of 2.49 mm. At the same time, ossification of the preopercle and opercle occurred in the operculum, and ossification of the maxilla, which forms the upper jaw, and the dentary bones, which form the lower jaw, began. In addition, ossification of the vertebra occurred by formation of 7 vertebral centra and the neural spine in the abdominal vertebra. When the juveniles reached an average (BL) of 5.22 mm, ossification of the nasal, lateral ethmoid, and alisphenoid bones occurred in the cranium; ossification of the endopterygoid and metapterygoid bones began in the palatine region; and ossification of the hypohyal and interhyal bones occurred in the hyoid arch. At an average (BL) of 20.9 mm, ossification of the basisphenoid bone in the cranium and the suborbital bone in the orbital region occurred. Ossification of the vertebra then occurred by the formation of long pairs of ribs from the third to the ninth abdominal vertebrae, completing osteological development.

• Journal of Oral Medicine and Pain
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• v.42 no.1
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• pp.8-15
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• 2017

Purpose: The purpose of this study was to assess the association of vocational interest and personality with temporomandibular disorders (TMD). Methods: Four hundred and fourteen college students in Gyeonggi-do completed Vocational Preference Inventory L form and a questionnaire and collected data were analyzed by R program. Results: The percentage of subjects who responded that they had at least one contributing factor for TMD was significantly different among 27 two-letter Holland codes (p<0.05). The two-letter Holland codes of which the first-letter was social (S) (S artistic [A], S investigative [I], S realistic [R], S conventional [C], S enterprising [E]) or C (CE, CS, CA, CI) had tendency of having the relatively higher prevalence of symptoms and contributing factors for TMD. Among 6 one-letter Holland codes, the prevalence of a symptom of frequent fatigue in the jaw and a habit of gum chewing showed the significant difference (p<0.05). E code seemed to have lower prevalence of a symptom of frequent fatigue in the jaw than other codes. S code appeared to use chewing gum more frequently than other codes. High scorers on emotional instability showed the significantly higher prevalence of TMD symptoms (p<0.05) and contributing factors for TMD (p<0.001) than low scorers. Furthermore, high scorers on emotional instability had significantly higher mean scales of the number of positive answers of TMD symptoms (p<0.01) and of contributing factors for TMD (p<0.001) than low scorers. Conclusions: Symptoms and contributing factors for TMD were related to emotional instability. Vocational Preference Inventory L form might be utilized in assessing emotional factors of persons with TMD symptoms.

• Progress in Medical Physics
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• v.9 no.3
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• pp.127-136
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• 1998

On-line geometrical quality assurance system has been developed using electronic portal imaging system(OQuE). EPID system is networked into Pentium PC in order to transmit the acquisited images to analysis PC. Geometrical QA parameters, including light-radiation field congruence, collimator rotation axis, and gantry rotation axis can be easily analyzed with the help of graphic user interface(GUI) software. Equipped with the EPID (Portal Vision, Varian, USA), geometrical quality assurance of a linear accelerator (CL/2100/CD, Varian, USA), which is networked into OQuE, was performed to evaluate this system. Light-radiation field congruence tests by center of gravity analysis shows 0.2～0.3mm differences for various field sizes. Collimator (or Gantry) rotation axis for various angles could be obtained by superposing 4 shots of angles. The radius of collimator rotation axis is measured to 0.2mm for upper jaw collimator, and 0.1mm for lower jaw. Acquisited images for various gantry angles were rotated according to the gantry angle and actual center of image point obtained from collimator axis test. The rotated images are superpositioned and analyzed as the same method as collimator rotation axis. The radius of gantry rotation axis is calculated 0.3mm for anterior/posterior direction (gantry 0$^{\circ}$ and 170$^{\circ}$) and 0.7mm for right/left direction(gantry 90$^{\circ}$ and 260$^{\circ}$). Image acquisition for data analysis is faster than conventional method and the results turn out to be excellent for the development goal and accurate within a milimeter range. The OQuE system is proven to be a good tool for the geometrical quality assurance of linear accelerator using EPID.