• The Journal of Korean Academy of Prosthodontics
• /
• v.33 no.1
• /
• pp.32-47
• /
• 1995

The purpose of this study was to determine the displacement of prosthesis & abutment and the stress distribution patterns induced in the periodontium by applying force to the fixed prosthesis. Two levels of periodontal support were compared using two-dimensional finite element stress analysis after placement of 3unit or 4 unit fixed partial denture(FPD) in case of missing of the lower first molar. Concentrated vertical load was delivered at the cusp tip of the second bicuspid or the central fossa of the pontic. The following results were obtained : 1. The greater the loss of alveolar bone in abutment teeth area, the greater the displacement of FPD and the stress concentration in alveolar bone around abutment. 2. The amount and direction of displacement and distribution of stress in the 4-unit FPD was better than those in the 3-unit FPD. 3. Multiple abutments reduced the amount of mesial and downward displacement of the weaked abutments and more uniformly distributed the stresses.

• Journal of Chest Surgery
• /
• v.52 no.2
• /
• pp.100-104
• /
• 2019

Shone complex is a rare congenital disorder that involves 4 obstructive lesions of the left heart, as follows: parachute mitral valve, supravalvular mitral ring, subaortic stenosis, and coarctation of the aorta. Incomplete forms with 2 or 3 of these lesions in adult patients have been rarely reported in the literature, meaning that insufficient general data exist concerning the surgical strategy and clinical follow-up. Herein, we report the case of a 31-year-old woman with a diagnosis of incomplete form of Shone complex with parachute mitral valve and coarctation of the aorta who underwent successful single-stage surgical repair.

• Animal Systematics, Evolution and Diversity
• /
• v.38 no.1
• /
• pp.14-19
• /
• 2022

Leptochiton Gray, 1847 is one of the most ancient chiton groups which includes more than 130 species that occur in cold and deep waters worldwide. Due to their small-sized body, they are often confused as juveniles of other chiton species. Moreover, lack of morphological information makes species identification of this group very challenging. To date, only two Leptochiton species(L. fuliginatus and L. rugatus) have been reported from Korean waters. In this study, we found L. hakodatensis(Thiele, 1909) for the first time in Korea and described microscopic morphological characters of valves (tegmentum sculpture), girdle scale, and radula using a scanning electron microscopy (SEM). Leptochiton hakodatensis is morphologically similar to L. fuliginatus and L. rugatus, but differently characterized by having dorso-ventrally rounded (not carinated) intermediate valves, girdle (perinotum) scales sculptured with 4-7 longitudinal ribs, and bicuspid major lateral teeth of radula. In addition to morphological examination, we determined the partial mitochondrial cytochrome c oxidase subunit I(cox1) as a DNA barcode sequence information. This is the first report that describes microscopic characters (tegmentum of valves, girdle structure, and radula) of L. hakodatensis using a SEM. This study provides a morphological basis for describing Leptochiton species and discovery of a "hidden" species of this genus.

• Imaging Science in Dentistry
• /
• v.44 no.3
• /
• pp.221-227
• /
• 2014

Purpose: This study aimed to investigate the clinical anatomy of lower premolar roots in a Spanish population by using cone-beam computed tomography (CBCT), correlating findings with patient gender and tooth type. Materials and Methods: Using 70 CBCT images, we evaluated 126 healthy, untreated, well-developed lower premolars. The number and morphology of roots and root canals, and the foramina number were assessed. Results for gender and tooth type were compared using the chi-squared and ANOVA tests. Results: The average length of teeth and roots was significantly higher in men (p=0.00). All 126 premolars had a single root. One canal was found in 83.3% of the premolars, with no gender or tooth type differences; Vertucci configuration types I and V were the most prevalent. The first premolars showed significantly greater variability than the second premolars (p=0.03). A single apical foramen was found in 89.7% of the premolars, with no differences by tooth type. Women had a significantly higher prevalence of two apical foramina than men (p=0.04). Some degree of curvature was observed in 65% of the premolars, with no differences by gender or tooth type. A root angle of more than $20^{\circ}$ was found in 12.98% of the premolars, without any differences by gender or tooth. Conclusion: All premolars were single-rooted. One canal had the most prevalent morphology. More variability in canal anatomy was found in the first premolars. Curvatures greater than $20^{\circ}$ were found at less than 5 mm from the apex.

• The korean journal of orthodontics
• /
• v.24 no.3 s.46
• /
• pp.535-546
• /
• 1994

The research work has been conducted in order to establish facts on posterior available space in patients with crowding. The relation between crowding and posterior available space was worked out through a cross sectinal study of fifty eight patients showing class I malocclusion. In addition, a longitudinal overlapping study was done by examing twenty patients who had their bicuspid extracted and forty nine patients who did not, at the orthodontic department of dental clinic affiliated in Chosun University. The patients had been examined for three years and eight months on a regular basis, and the study yielded the following conculusion. 1. There was a great difference in posterior available space between patients with serious crowding and those with slight crowding. The former marked 15.2mm of posterior available space and the latter 19.9mm. 2. Posterior crowding index was acquired by joint consideration of the diameter of posterior teeth and posterior available space, and manifested the highest relationship with crowding among measured items. 3. Patients who had their bicuspids extracted exhibited increase in posterior available space of 1.6mm/year and those who did not 1.8mm/year. 4. The absorption of anterior border of ramus turned out to be most deeply related with the increase of posterior available space. 5. Anterior border of ramus was absorbed at the average rate of 0.7mm/year during the period of observation. 6. The extraction of bicuspids had little influnce on the change in posterior available space.

• The korean journal of orthodontics
• /
• v.47 no.6
• /
• pp.344-352
• /
• 2017

Objective: The purpose of this study was to compare the changes induced in the pharyngeal airway space by orthodontic treatment with bodily retraction of the mandibular incisors and mandibular setback surgery without extraction. Methods: This retrospective study included 63 adult patients (32 men and 31 women). Thirty-three patients who had been treated via four-bicuspid extraction and bodily retraction of the mandibular incisors (incisor retraction, IR group) were compared with 30 patients who had been treated via mandibular setback surgery (MS group) without extraction. Lateral cephalograms were acquired and analyzed before (T1) and after treatment (T2). Results: The superior pharyngeal airway space did not change significantly in either group during treatment. The middle pharyngeal airway space decreased by $1.15{\pm}1.17mm$ and $1.25{\pm}1.35mm$ after treatment in the IR and MS groups, respectively, and the decrease was comparable between the two groups. In the MS group, the inferior pharyngeal airway space (E-IPW) decreased by $0.88{\pm}1.67mm$ after treatment (p < 0.01). The E-IPW was larger in the MS group than in IR group at T1, but it did not differ significantly between the two groups at T2. No significant correlation was observed between changes in the pharyngeal airway space and the skeletal and dental variables in each group. Conclusions: The middle pharyngeal airway space decreased because of the posterior displacement of the mandibular incisors and/or the mandibular body. The E-IPW decreased only in the MS group because of the posterior displacement of only the mandibular body.

• Journal of Chest Surgery
• /
• v.51 no.5
• /
• pp.322-327
• /
• 2018

Background: This study evaluated the early and long-term outcomes of surgical aortic valve replacement (AVR) in elderly patients in the era of transcatheter aortic valve implantation. Methods: Between 2001 and 2018, 94 patients aged ${\geq}75years$ underwent isolated AVR with stented bioprosthetic valves for aortic valve stenosis (AS). The main etiologies of AS were degenerative (n=63) and bicuspid (n=21). The median follow-up duration was 40.7 months (range, 0.6-174 months). Results: Operative mortality occurred in 2 patients (2.1%) and paravalvular leak occurred in 1 patient. No patients required permanent pacemaker insertion after surgery. Late death occurred in 11 patients. The overall survival rates at 5 and 10 years were 87.2% and 65.1%, respectively. The rates of freedom from valve-related events at 5 and 10 years were 94.5% and 88.6%, respectively. The Society of Thoracic Surgeons (STS) score (p=0.013) and chronic kidney disease (p=0.030) were significant factors affecting long-term survival. The minimal p-value approach demonstrated that an STS score of 3.5% was the most suitable cut-off value for predicting long-term survival. Conclusion: Surgical AVR for elderly AS patients may be feasible in terms of early mortality and postoperative complications, particularly paravalvular leak and permanent pacemaker insertion. The STS score and chronic kidney disease were associated with long-term outcomes after AVR in the elderly.

• Journal of Chest Surgery
• /
• v.40 no.7 s.276
• /
• pp.508-511
• /
• 2007

The causes of aortic dissection are usually hypertension, connective tissue disease such as Marfan syndrome, congenital valvular abnormality such as bicuspid aortic valve, iatrogenic injury, pregnancy and drugs. Previous studies have shown that 50% of all dissections in women less than 40 years age were associated with pregnancy. Almost all aortic dissections during pregnancy occur during the third trimester or during labor and delivery. Marfan's syndrome is a particularly important predisposing factor for aortic dissection during pregnancy. We report here on a case of surgical treatment for acute type II aortic dissection in a Marfan syndrome patient who was 24 weeks pregnant, and we include a review of literature.

• The korean journal of orthodontics
• /
• v.24 no.4 s.47
• /
• pp.957-967
• /
• 1994

The purpose of this study was to evaluate the effects of different bases of ceramic brackets on shear bond strength and to observe failure patterns of bracket bondings. Lower bicuspid brackets whose bases designed for the macromechanical and silane treated chemical bonding those for silane treated chemical bonding, those for micromechanical bonding, and those for macromechanical bonding were tested as experimental groups, and foil mesh-backed metal brackets as a control group. All the brackets were bonded with $Mono-Lok\;2^{(TM)}$ on the labial surface of extracted human lower bicuspids after etching the enamel with $38\%$ phosphoric acid solution for 60 seconds. The shear bond strengths were measured on the universal test machine after 24 hours passed in the $37^{\circ}C$ water bath. The gathered data were evaluated and tested by ANOVA and Duncan's multiple range test, and those results were as follows. The shear bond strengths of brackets for macromechanical and chemical bonding, those for chemical bonding, and those for micromechanical bonding were not different (p>0.05), but showed statistically higher than those of metal bracket and those of ceramic bracket for micromechanical bonding(p<0.05). The shear bond strengths of ceramic bracket for micromechanical bonding showed statistically lower than those of metal bracket(p<0.05). The enamel fractures and/or ceramic bracket fractures were observed in the cases of higher bond strength than that of metal bracket. These results supported that silane treated base of ceramic bracket show higher shear bond strength than that of metal bracket, and suggested that micromechanical form of ceramic bracket bases show higher shear bond strength than that of macromechanical form.

• Journal of Periodontal and Implant Science
• /
• v.46 no.6
• /
• pp.396-404
• /
• 2016

Purpose: The aim of this retrospective study was to determine the association between dental implants in the posterior region and traumatic occlusion in the adjacent premolars, using data collected during from 2002 to 2015. Methods: Traumatic occlusion in the adjacent premolars was assessed by examining clinical parameters (bleeding on probing, probing pocket depth, fremitus, and tooth mobility) and radiographic parameters (loss of supporting bone and widening of the periodontal ligament space) over a mean follow-up of 5 years. Clinical factors (gender, age, implant type, maxillary or mandibular position, opposing teeth, and duration of functional loading) were evaluated statistically in order to characterize the relationship between implants in the posterior region and traumatic occlusion in the adjacent premolars. Results: The study inclusion criteria were met by 283 patients, who had received 347 implants in the posterior region. The incidence of traumatic occlusion in the adjacent premolars was significantly higher for splinted implants (P=0.004), implants in the maxillary region (P<0.001), and when implants were present in the opposing teeth (P<0.001). The other clinical factors of gender, age, and duration of functional loading were not significantly associated with traumatic occlusion. Conclusions: This study found that the risk of traumatic occlusion in the adjacent premolars increased when splinted implants were placed in the maxillary molar region and when the teeth opposing an implant also contained implants.