• Restorative Dentistry and Endodontics
• /
• 제37권4호
• /
• pp.201-206
• /
• 2012

Objectives: The purpose was to investigate the preference and usage technique of NiTi rotary instruments and to retrieve data on the frequency of re-use and the estimated incidence of file separation in the clinical practice among general dentists. Materials and Methods: A survey was disseminated via e-mail and on-site to 673 general dentists. The correlation between the operator's experience or preferred technique and frequency of re-use or incidence of file fracture was assessed. Results: A total of 348 dentists (51.7%) responded. The most frequently used NiTi instruments was ProFile (39.8%) followed by ProTaper. The most preferred preparation technique was crown-down (44.6%). 54.3% of the respondents re-used NiTi files more than 10 times. There was a significant correlation between experience with NiTi files and the number of re-uses (p = 0.0025). 54.6% of the respondents estimated experiencing file separation less than 5 times per year. The frequency of separation was significantly correlated with the instrumentation technique (p = 0.0003). Conclusions: A large number of general dentists in Korea prefer to re-use NiTi rotary files. As their experience with NiTi files increased, the number of re-uses increased, while the frequency of breakage decreased. Operators who adopt the hybrid technique showed less tendency of separation even with the increased number of re-use.

• Journal of Dental Rehabilitation and Applied Science
• /
• 제23권4호
• /
• pp.293-302
• /
• 2007

I. Objectives The purpose of this study was to compare the shaping ability between the single length technique performed with Mtwo instruments (VDW, Munich, Germany) and the crown-down technique using K3 (SybronEndo, West Collins, CA, USA) and RaCe (FKG, La Chaux-de-Fonds, Switzerland) instruments. II. Materials & Methods Forty five curved canals in resin blocks were equally divided in to three groups. Group 1 (Mtwo) was instrumented used the full length of canal according to the manufacturer's instructions. The simulated canals was prepared to an instrument size of 35, 0.04 taper canal terminus. In group 2 (Race) and group 3 (K3) was instrumented in a crown-down manner and prepared to an instrument size of 30, 0.06 taper canal terminus. Pre- and post-instrumentation images were scanned and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 7 measuring points, beginning 1mm from the end point of preparation. Differenced of centering ratio were statistically analyzed using One-way ANOVA followed by Duncan's test. II. Results & Conclusion There was no significant difference on 1, 2, 3 and 7mm measuring point. At 4 and 5 measuring point, significant difference showed between the Mtow instruments and other two instruments. (p<0.05)

• Journal of the korean academy of Pediatric Dentistry
• /
• 제49권1호
• /
• pp.104-112
• /
• 2022

The purpose of this study is to analyze the fracture resistance of reattached tooth according to the resin materials and tooth preparation type under physiological conditions. Uncomplicated crown fracture in the oblique direction was reproduced on the extracted 64 anterior teeth. Depending on the composite resin material, reattachment was performed using a flowable resin and a packable resin. Depending on retentive forms, reattachment was performed using simple reattachment, 1.0 mm × 1.0 mm labial chamfer bevel, 1.0 mm × 1.0 mm lingual chamfer bevel and 1.0 mm × 1.0 mm circumferential bevel. A load was applied to the palatal surface of the tooth using a universal testing machine at an angle of 125 degree, which is the interincisal angle of normal children. Under the masticatory pressure condition, fracture resistance of lingual chamfer groups was 28.28 ± 7.41 MPa and 27.54 ± 4.45 MPa, which was significantly higher than those of simple reattachment groups, 17.21 ± 5.87 MPa and 20.10 ± 6.00 MPa, in both flowable and packable resin groups. When considering the lingual force similar to masticatory pressure, the fragment retention was significantly improved when the lingual chamfer was formed compared to the simple reattachment. Clinicians may consider the design of the lingual chamfer in order to improve fracture resistance to masticatory pressure during fragment reattachment.

• Journal of the korean academy of Pediatric Dentistry
• /
• 제39권2호
• /
• pp.199-205
• /
• 2012

Although the stainless steel crowns have been recognized as the most effective and durable form of restoration for primary molars, they have been regarded by many dentists as having definite demerits such as invasive nature of procedural complexity and behavioral aspects of children. As an alternative to conventional technique of stainless steel crown restoration, the Hall technique was first introduced in 1988, which is characterized by just pushing the pre-contoured, cement filled crown form onto the abutment molar with no local anesthesia, no caries removal, no tooth preparation. According to several reports, this can slow, arrest, or even reverse the progress of caries. In addition, its atraumatic feature gives less discomfort and stress to children than conventional one, which is thought excellent especially in younger children. Also, It has been reported to be effective and acceptable to dentist, child patients and their parents. In this case study, three children with age of 4 years 5 months, 4 years 10 months, 6 years 4 months were treated with stainless steel crowns using Hall technique on first primary molar respectively. The teeth were free from pulpal, periapical pathology. After follow up of about 3 to 6 months period, the results showed clinically successful outcomes without any marked complication in pulp, tooth or soft tissue till now. But, it should be kept in mind that this technique is not proper to every child, every carious molar, or every dentist. Thorough distinction of indicated cases and continuous follow-up check is highly required. Conclusively, Hall technique might be an effective and realistic minimally invasive alternative for the carious primary molars especially in younger or disabled children, despite potential doubts on its efficacy and some definite limitations.

• The Journal of Korean Academy of Prosthodontics
• /
• 제57권1호
• /
• pp.81-87
• /
• 2019

Patients with Down's syndrome have several dental complications such as small teeth caused by underdevelopment of dentin and enamel, periodontitis, agenesis of teeth, prolonged retention of primary teeth and malocclusion due to narrow palate. Removable denture with maxillary double crowns would be a good treatment option to solve the problems of the patient with Down's syndrome. Double crowns compensate the insufficient support and retention of denture and easily solve the cross bite problem. Double crowns also allow easy repair of denture in case of abutment teeth extraction. In this case, 26-year-old female patient with Down's syndrome and dental phobia had small number of teeth with enamel hypoplasia, prolonged retention of primary teeth and dental cross bite. Prosthetic treatment was done using removable denture with double crowns in the maxilla. In the mandible, teeth preparation was done on enamel margin without anesthesia. Anterior laminate and posterior complete zirconia crown restorations were performed. As a result, the cross bite was effectively corrected by denture with double crowns. Pronunciation and appearance were also improved without extraction of teeth and dental anesthesia.

• The Journal of Korean Academy of Prosthodontics
• /
• 제59권3호
• /
• pp.319-332
• /
• 2021

With the rapid development of aesthetic ceramic materials and resin adhesives, the transition from metal ceramic crown to all-ceramic restoration is being actively carried out. When making porcelain restorations, the advantages can be maximized only when appropriate forms and techniques are used. Recently, an esthetic partial-coverage restoration method with supra-gingival margins was introduced by applying a minimally invasive tooth removal method that preserves enamel as much as possible and enhances adhesion efficiency. Through this, various advantages such as minimization of tooth structure removal and ease of excess cement removal can be obtained. In addition, since this manufacturing method does not require cord packing, it is possible to save time for impression taking and reduce patient discomfort. Furthermore, the margins can be clearly obtained without the intervention of gingival fluid or blood, making it possible to manufacture more accurate restorations. In the following cases of patients with partial tooth defects, esthetic ceramic partial-coverage restorations with supra-gingival margin was applied using minimally invasive tooth preparation method according to the concept of adhesive dentistry. Therefore, unnecessary tooth abutment preparation was prevented and residual tooth structure could be preserved as much as possible. After delivery of the ceramic partial-coverage restorations, favorable outcome was obtained.

• The Journal of the Korean dental association
• /
• 제45권6호통권457호
• /
• pp.362-369
• /
• 2007

The aim of this study was to investigate the effect of the hybrid instrumentation method with ProTaper and ProFile on the change of root canal area and distance from the canal to the root surface after canal shaping. The mesial canals of twenty extracted mandibular first molars having $10-20^{\circ}\Delta$ curvature were scanned using X-ray microcomputed tomography (XMCT)-scanner before root canals were instrumented. They were divided into four groups (n=10 canals ter group). In Group 1, root canals were instrumented by the step-back technique with stainless steel K-Flexofile after coronal flaring. The remainders were instrumented by the crown-down technique with, ProTaper system (Group 2), ProFile (Group 3) or ProTaper (Group 4). All canals were prepared up to size 25 at the end-point of preparation and scanned again. Pre- and post-operative cross-sectional images of 1, 3, 5, and 7 mm from the apical foramen were compared. For each level, change of cross-sectional canal are and distance to the nearest external root surface was calculated using Adobe Photoshop 6.0 and image software program. In the change of cross-sectional area, Group 4 was less than Group 2 at 3 mm and 5 mm level (p<0.05). In the difference of the distance from the canal to the root surface after canal shaping, Group 4 was least among the other groups at 7 mm level (p<0.05). According to the results, the methods using ProFile or K file only and the hybrid instrumentation technique using ProTaper and ProFile are more appropriate methods of canal preparation than ProTaper system for narrow of curved canals.

• Journal of the East Asian Society of Dietary Life
• /
• 제9권1호
• /
• pp.55-63
• /
• 1999

This research was conducted to estimate waste rates of 69 food items after pre-preparation and amounts of food wastes disposed and it's reduction effect by education in some institutional foodservices for reduction of the food wastes. The result are as follows: 1. The waste rates were 55.40% for sweet corn, 5.73% for potatoes, 19.14% for sweet potatoes, and 33.47% for chestnuts. 2. The waste rates of fruits were 0.21-49.36%. Food items with over 40% waste rate were banana, watermelon, and pineapple. 3. The waste rates of vegetables were 1.14-52.90%. The number of foods with under 10% waste rate were 14 items(red pepper, green pepper, chard, and so on), 10-20% was 9 items(perilla leaf, chinese cabbage, ginger root, and so on), 20-30% was 5 items(root of chinese bellflower, garlic, radish-leaves, burdock, welsh onion-large type), 30-40% was 3 items(shepherd's purse, head lettuce, kale) and over 40% was 3 items(water dropwort, crown daisy, mallow). 4. The waste rates were 24.30% in chicken, 9.53-13.79% in eggs, and 9.30-55.32% in fishes. The waste rates of vegetables and fishes were higher than those of other food groups. 5. There were significantly different in amount of food wastes disposed (g/person/day) to institutional foodservices (hospital＞industrial institution＞ Korean restaurant＞elementary school). The amount of food wastes disposed, especially amount in pre-preparation phase, after education for reduction of food wastes was significantly reduced. Since these study results show significant deviations in food waste rates and education effect, there should be more studies for standard waste rates of each food and systematic education method for reduction of food wastes.

• Restorative Dentistry and Endodontics
• /
• 제18권1호
• /
• pp.205-213
• /
• 1993

The purpose of the study was to evaluate the degree of the marginal leakage of esthetic restorative materials on root caries restoration. 120 cavities were prepared to $90^{\circ}$ butt joint on all margins on the crown and root portion, and divided into 4 groups. The four groups of cavity were filled with Amalgam(Dongmuyung Dental Alloy Co., Ltd, KOREA), Silux$^{(R)}$(3M Co., USA)-Scotch Bond 2$^{(R)}$(3M Co., USA), Silux$^{(R)}$-All Bond$^{(R)}$(BISCO USA), and GC Fuji II$^{(R)}$(G-C Co., JAPAN) respectively. The apical margin of the preparation was finished to leave a flash of restorative material. The coronal margin of the preparation was finished not to leave a flash of restorative material. All specimens were sectioned longitudinally with Isomet Low speed saw(Buether Ltd, USA). The degree of dye penetration was evaluated as the parameter of marginal leakage under the stereoscope. The results were as follows. 1. At the enamel and dentin/cementum margins, the margin were finished to leave a flash of material showed less marginal leakage than that were finished not to leave a flash of material (P<0.001). 2. The enamel margins showed less marginal leakage than the dentin/cementum margins(P<0.001). 3. There was no significant difference in the degree of the marginal leakage between Silux$^{(R)}$-Scotch Bond 2$^{(R)}$ group and Silux$^{(R)}$-All Bond$^{(R)}$ group.

• Korean Journal of Heritage: History & Science
• /
• 제55권1호
• /
• pp.199-222
• /
• 2022

It has been 100 years since the excavation of Geumgwanchong (Gold Crown Tomb), a tomb that was accidentally discovered in Noseo-ri, Gyeongju at the end of September 1921 during Japanese colonial rule. Although it is known for its discovery, not only in the Korean Peninsula but also in Asia and beyond, the excavation report was published in Japanese and English by the Government-General of Korea in 1924 and 1928, three years after the excavation. TOMB "KINKANTSUKA" or THE GOLD CROWN TOMB at KEISHU, AND ITS TREASURES) was published as a series of books and picture books. The excavation report was prepared by Kosaku Hamada (濱田耕作), who was a member of the Ruins Investigation Committee of the Japanese Government-General of Korea (later became the President of Kyoto Imperial University, Kyoto, Japan), and Sueji Umehara (梅原末治), who was commissioned to investigate the remains of the Japanese Government-General of Korea. In this paper, the preface was written in July 1922, about half a year after the excavation of tombs, which was much earlier than the official reports, in the 'Korean and Chinese reading book (稿本 高等朝鮮語及漢文讀本 巻五)' by Hamada Kosaku (濱田耕作) for high school students in Korea, which was titled 'New Excavated Artifacts in Gyeongju (慶州의 新發掘品)' with a subtitle '絶大의 發見', a slightly awkward expression in Korean, but it means 'a very big discovery'. The meaning has been introduced as a single unit, emphasizing its significance in terms of the achievements of the excavation of Geumgwanchong, academic and archaeological discoveries, and cultural history in Korean language rather than Japanese language. Since the manuscript was written immediately after the excavation, the excitement as an archaeological researcher at the time of the excavation and expectations for future research can be read as it is. In this paper, I would like to introduce the voice of the excited field leader of the Japanese Government-General of Korea after the excavation of Geumgwanchong in 2022, the 100th anniversary of the writing. In addition, the process from the discovery of the tomb to the preparation of the report was summarized in one chronological table to make it easier to understand the series of flows.