• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.247-252
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• 2008

Purpose: Passive eruption is characterized by the apical shift of the dentogingival junction. As this occurs, the length of the clinical crown increases as the epithelial attachment migrates apically. Altered passive eruption occurs when the margin of gingiva is malpositioned incisally on the anatomic crown in adulthood and results in excessive gingiva. The purpose of this article is to evaluate esthetic results of crown lengthening procedure in altered passive eruption.s. Materials and Methods: Three patients who complained "My front teeth look too short" were included. Bone sounding with periodontal probe revealed that alveolar bone crest was close to CEJ. Based on the diagnostic information, a diagnosis of altered passive eruption was made. They were performed apically positioned flap procedure with osseous resection. Results: Six months later, all patients achieved favorable esthetic results and gingival margins were healthy and stable. Conclusion: When the diagnostic procedures reveal alveolar bone crest levels approximating the CEJ, apically positioned flap procedure with osseous resection is indicated.

• The Journal of Advanced Prosthodontics
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• v.13 no.2
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• pp.79-88
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• 2021

Purpose. To assess peri-implant stress distribution using finite element analysis in implant supported fixed partial denture with occlusal schemes of cuspally loaded occlusion and implant protected occlusion. Materials and methods. A 3-D finite element model of mandible with D2 bone with partially edentulism with unilateral distal extension was made. Two Ti alloy identical implants with 4.2 mm diameter and 10 mm length were placed in the mandibular second premolar and the mandibular second molar region and prosthesis was given with the mandibular first molar pontic. Vertical load of 100 N and and oblique load of 70 N was applied on occlusal surface of prosthesis. Group 1 was cuspally loaded occlusion with total 8 contact points and Group 2 was implant protected occlusion with 3 contact points. Results. In Group 1 for vertical load, maximum stress was generated over implant having 14.3552 Mpa. While for oblique load, overall stress generated was 28.0732 Mpa. In Group 2 for vertical load, maximum stress was generated over crown and overall stress was 16.7682 Mpa. But for oblique load, crown stress and overall stress was maximum 22.7561 Mpa. When Group 1 is compared to Group 2, harmful oblique load caused maximum overall stress 28.0732 Mpa in Group 1. Conclusion. In Group 1, vertical load generated high implant stress, and oblique load generated high overall stresses, cortical stresses and crown stresses compared to vertical load. In Group 2, oblique load generated more overall stresses, cortical stresses, and crown stresses compared to vertical load. Implant protected occlusion generated lesser harmful oblique implant, crown, bone and overall stresses compared to cuspally loaded occlusion.

• Restorative Dentistry and Endodontics
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• v.36 no.1
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• pp.59-65
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• 2011

Objectives: The purpose of this study is to compare the apical transportation and working length change in curved root canals created in resin blocks, using 3 geometrically different types of Ni-Ti files, K3, NRT, and Profile. Materials and Methods: The curvature of 30 resin blocks was measured by Schneider technique and each groups of Ni-Ti files were allocated with 10 resin blocks at random. The canals were shaped with Ni-Ti files by Crown-down technique. It was analyzed by Double radiograph superimposition method (Backman CA 1992), and for the accuracy and consistency, specially designed jig, digital X-ray, and CAD/CAM software for measurement of apical transportation were used. The amount of apical transportation was measured at 0, 1, 3, 5 mm from 'apical foramen - 0.5 mm' area, and the alteration of the working length before and after canal shaping was also measured. For statistics, Kruskal-Wallis One Way Analysis was used. Results: There was no significant difference between the groups in the amount of working length change and apical transportation at 0, 1, and 3 mm area (p = 0.027), however, the amount of apical transportation at 5 mm area showed significant difference between K3 and Profile system (p = 0.924). Conclusions: As a result of this study, the 3 geometrically different Ni-Ti files showed no significant difference in apical transportation and working length change and maintained the original root canal shape.

• The Journal of the Acoustical Society of Korea
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• v.2 no.1
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• pp.1-10
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• 1983

The presence of the sound tube and resonance cavity is unique in Korea Brahman Bells which is no examples in other country bells in the world. The sound tube erected in the crown is effective to emit the fundamental tone of the bell when the condition of resonant transmissibility is satisfied. The results of our analysis shows that the optimum length of the sound tube in the Bell Emile is 96cm but is not the present length, 77cm. The resonance cavity erected underneath the lip of the Bell Emile is found to be for the resonance of standing waves in the space including both bell cavity and resonance cavity and resonance cavity to the fundamental tone of the bell itself, in order that the strongest vibration can last long by least energy and lengthen the reverberation of the bell. Some historical remarks are also made on the magic flute, MANPASIKJUK, which was in existence in Shilla that can lull all evil waves, such as plagues, storms, droughts, famines and even enemies. The sound tube erected in the crown of the bell was originated in this magic flute. Finally, a strong proposal is advanced on the new national symbol of Korean traditional cultural assets. Indeed, it should be highly recommended that the Great King's Bell Emile would be the only real symbol of our national cultural assets by its own right of excellency and richness in every aspect of arts and sciences.

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.30-35
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• 2006

To evaluate the change of working length with various instrumentation techniques in curved canals, working length and canal curvature were determined before and after canal instrumentation in buccal or mesial canals of extracted human molars. Stainless steel K-files ($MANI^{(R)}$, Matsutani Seisakusho Co. Takanezawa, Japan), nickel-titanium K-files (Naviflex $NT^{TM}$, Brassier, Savannah, USA) , $ProFile^{(R)}$, and ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland) were used to prepare the canals with crown-down technique. In two hand instrumentation groups coronal flaring was made with Gates Glidden burs. Apical canals were instrumented until apical diameter had attained a size of 30. Positional relation between the tooth apex and the $\#10$ K-file tip was examined by using AutoCAD 2000 (Autodesk Corp., San Rafael. CA, USA) under a stereomicroscope before and after coronal flaring, and after apical instrumentation. Degree of canal curvature was also measured with Schneider's method in radiographs. Data of working length and canal curvature changes were statistically analyzed with one-way ANOVA and Tukey's studentized range test. Working length and canal curvature were decreased significantly in each step in all instrumentation groups. Coronal flaring using Cates Glidden burs in hand instrument groups and whole canal instrumentation using stainless steel hand K-files caused significantly more working length change than in ProFile instrumentation group (p<0.05). The result of this study demonstrates that all of the above kinds of instrumentation in curved canals cause reduction of working length and canal curvature at each instrumentation steps, and hand instrumentation causes more working length change than ProFile.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.512-517
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• 1993

The cold rolled strip meets continuously rising demands on the less deviation of thickness at the width direction of their rolled products. Especially, the special interest has been to find the methods to reduce the edge drop which influences seriously on the yield losses and the quality of the rolled products. In this study, the influence of hot coils on the thickness profile of cold rolled strip was analyzed. For obtainint the tapered work roll shig\ft conditions, the thermal crown and the flattening between the work roll and the strip were calculated, and the main parameters which have mostly effects on the edge drop were simulated. Also the obtained conditions from the simulation were applied to Tandem Cold Rolling Mill to investigate the change of the edge drop and the crown ratio depending on the amount of work roll taper and the length of contact of taper. The results of the application led to better thickness profile than conventional one.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.2
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• pp.176-186
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• 2016

This study was performed to compare the shape and dimension of anterior zirconia crowns to other pediatric crowns using a three-dimensional scanner to investigate adequate amount of tooth preparation. Primary central and lateral anterior zirconia crowns, stainless steel crowns and celluloid strip crowns were scanned by a three-dimensional scanner. Outer and inner surfaces of zirconia and stainless steel crowns, and outer surface of celluloid strip crowns were analyzed. In outer scanned images, all sizes of central and lateral size 1 zirconia crown had the largest labiolingual diameter among the three crowns. In inner scanned images, zirconia crown's mesiodistal diameter was 0.7-1.0 mm smaller and crown length was approximately 1 mm shorter than those of stainless steel crowns. Zirconia crown's labiolingual diameter was larger in central crowns whereas it was smaller in lateral crowns than that of stainless steel crowns. Recommended preparation required for zirconia crown is incisal 2.5-3.0 mm, mesiodistal 1.5-2.0 mm, labial 0.5-1.0 mm. Cingulum should be trimmed parallel to the long axis. No more lingual reduction is needed in central incisors whereas additional 0.5 mm reduction is suggested in lateral incisors.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.202-207
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• 2010

Plant growth promoting fungi (PGPF) are well known for the production of useful secondary metabolites. However, limited information is available on the gibberellin (GA) production capacity of PGPF of endophytic origin. In the current study, 15 fungal endophytes were isolated from the roots of Crown daisy, and then screened on Waito-c rice, in order to identify plant growth promoting fungi. The fungal isolate MH7 significantly increased the shoot length (12.1 cm) of Waito-c in comparison with control treatment (7.9 cm). In a separate experiment, the culture filtrate (CF) of MH7 significantly promoted the growth attributes of Crown daisy. The MH7 CF was analyzed for gibberellins and it contained all physiologically active gibberellins ($GA_1$, 1.37 ng/ml; $GA_3$, 5.88 ng/ml; $GA_4$, 8.62 ng/ml; and $GA_7$, 2.05 ng/ml) in conjunction with physiologically inactive $GA_9$ (0.83 ng/ml), $GA_{12}$ (0.44 ng/ml), $GA_{15}$ (0.74 ng/ml), $GA_{19}$ (1.16 ng/ml), and $GA_{20}$ (0.98 ng/ml). The CF of MH7 produced higher amounts of $GA_3$, $GA_4$, $GA_7$, $GA_9$, and $GA_{12}$ than wild-type Fusarium fujikuroi, which was used as a control for GA production. The fungal isolate MH7 was later identified as a new strain of Penicillium on the basis of its morphological characteristics and phylogenetic analysis of the 188 rDNA sequence.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.247-273
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• 1994

The purpose of this study was to evaluate the dental arch morphology and the occlusal characteristics in the Koreans from the dental-anthropological point of view. The sample consisted of dental stone casts obtained from 120 Korean adults and 142 Japanese adults. Japanese casts and Caucasian data had been preserved at the Dept, of Orthodontics of Tokyo Medical and Dental University. Tooth size and dental arch morphology of the Koreans were compared with that of the Japanese. On the other hand, the variations of 30 crown traits, categorized and quantitatively graded, were compared between two peoples and the frequency distribution of each crown traits were analyzed by means of Chi-square test. The results were summerized as followings ; 1. There was a significant sexual difference in dental arch length and width in the Korean, in which male had a longer and wider dental arch than female. There was a close resemblance for dental arch morphology between the Koreans and the Japanese, except for a little longer mandibular arch of the Japanese. 2. In general, Korean male had wider crown than female, particulary in central incisor,canine,1st molar of maxilla and canine, 1st and 2nd molar of mandible with significance. The Korean had wider maxillary first molar, smaller mandibular first and second molar than the Japanese in both sex. 3. In crown traits of the Korean, shovel-shaped incisor showed lower frequency distribution than in the Japanese, but higher than in the Caucasians. Frequency of incisor reduction was shown higher distribution than in the Japanese and the Caucasians. Carabelli's tubercle showed higher frequency distribution than in Japanese, but remarkably lower than in Caucasians.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.280-287
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• 2019

In the oral cavity, the teeth undergo wear and corrosion throughout their lives. Progressive and constant tooth wear is a natural phenomenon of aging, but wear and corrosion due to specific factors are pathological factors. It can cause pathological damage of the occlusal surface, aesthetic problems, dimensional loss and jaw joint disorders. This case is a 26-year-old female patient with general tooth abrasion and erosion on the entire dentition. Diagnostic wax-up was fabricated based on the information including digital facial analysis, physiological stabilization, and evaluation of anterior crown length. Through the digital analysis, the necessary guides for crown lengthening were prepared and the mastication function and esthetics were evaluated by using temporary crowns. Definitive prosthesis was fabricated with the zirconia restorations. The results were satisfactory when they were observed 3 months of follow-up.