• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.41-47
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• 2013

Maxillary canines are the most commonly impacted or ectopically erupted teeth. If we find the abnormality of maxillary canines early, we can manage it reasonably and systematically. If we cannot see the spontaneous normalization at the periodic recall, primary canine extraction will be the next treatment choice. However, if the primary canine is extracted too early, the extraction socket will be filled with hard bone and then the eruption pathway can be locked. So it is more beneficial to extract the primary canine at the period about 6 months before the normal canine eruption time. The next treatment plan can be surgical and orthodontic approaches before the root apical closure of the impacted canine. Sometimes, surgical extraction and further prosthetic procedure can be needed for a severely malposed impacted canine or badly resorpted incisor. This is the case of the idiopathic mesial movement of impacted maxillary canines.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.332-340
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• 2008

The purpose of this study was to evaluate the viability of periodontal ligament cell in rat teeth using slow cryopreservation method with magnetic field through MTT assay and TUNEL test. For each group, 12 teeth of 4 weeks old white female Sprague-Dawley rat were used for MTT assay, and 6 teeth in TUNEL test. The Maxillary left and right, first and second molars were extracted as atraumatically as possible under tiletamine anesthesia. The experimental groups were group1 (immediately extraction), group 2 (cold preservation at 4$^{\circ}C$ for 1 week), group 3 (rapid cryopreservation in liquid nitrogen), group 4 (slow cryopreservation with magnetic field of 1 G), and group 5 (slow cryopreservation). F medium was used as preservation medium and 10% DMSO as cryoprotectant. After preservation and thawing, the MTT assay and TUNEL test were processed. One way ANOVA and Scheffe method were performed at the 95% level of confidence. The value of optical density obtained after MTT analysis was divided by the value of eosin staining for tissue volume standardization. In both MTT assay and TUNEL test, it had showed no significant difference among group 3, 4, and 5. And group 3 had showed higher viability of periodontal ligament cell than group 2. From this study, slow cryopreservation method with magnetic field can be used as one of cryopreservation methods.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.298-305
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• 2016

The maxillary anteriors play an important role in esthetics. Therefore after extraction, it is crucial to preserve the hard tissue and soft tissue in order to promote esthetics of restoration. There are several challenges when restoring the maxillary anteriors via implant. Some of the challenges are be maintaining consistency with neighboring teeth in terms of shade, form, and texture : as well as having harmonious emergency with the gingival margin. In this case, a traumatized patient with crown-root fracture of the maxillary central and lateral incisors is presented. The cracked teeth were extracted, and implants were inserted with bone grafts to compensate the volume of damaged area of the maxillary anterior. Cantilever implant prosthetics were planned while precise adjustments to the gingival area were made using customized impression coping to perform the esthetic restorations. The final outcome of the treatment was satisfying in both esthetic and utilitarian perspective.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.13 no.2
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• pp.95-98
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• 2017

Due to hypodontia, poor oral hygiene, and significantly more prevalent periodontal disease, patients with Down syndrome show higher incidence of edentulism. Oral rehabilitation of such patients is imperative but challenging as high rates of prosthesis failure are reported due to malocclusion, high masticatory force, and parafunctional habits. As CAD/CAM(Computer-Aided Design and Computer Aided Manufacturing) is the recent trend in prosthodontics, this report discusses the application of CAD/CAM in a Down syndrome patient. A 25-year-old patient with Down syndrome was presented to the Department of Pediatric Dentistry, Yonsei University Dental Hospital for oral examination. 5 maxillary teeth were missing, 3 were fully impacted, and 4 had grade III mobility. The patient underwent general anesthesia for extraction of impacted and mobile teeth, implant surgery, and final impression for prosthesis. Afterwards, CAD/CAM was used to design and manufacture a 10-unit zirconia bridge. However the bridge was fractured after 18 months due to the patient's bruxism and high masticatory force. Final impression taking, bite registration, cast fabrication, cast scanning, and prosthesis designing were not needed as CAD/CAM data remained. Previous CAD/CAM design was used to remanufacture the zirconia bridge. Down syndrome patients have malocclusion, high masticatory force, and parafunctional habits which increase the possibility of prosthesis fracture. CAD/CAM is beneficial for Down syndrome patients as previous digital records can be utilized for prosthesis repair or remake. In detail, application of CAD/CAM in remanufacturing decreases patient's discomfort of impression taking, shortens and simplifies dental laboratory procedures, and reduces clinician's effort of taking detailed final impressions or accurate bite registration. In conclusion, oral rehabilitation using CAD/CAM provides not only satisfactory levels of comfort, stability, and esthetics, but also easier repair or remake compared to conventional prostheses.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.23-34
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• 1979

In this study, the adhesive strength of three commercial polycarboxylate cements to ten types of dental casting alloys, such as gold, palladium, silver, indium, copper, nickel, chromium, and human enamel and dentine were measured and compared with that of a conventional zinc phosphate cement. The $8.0mm{\times}3.0mm$ cylindrical alloy specimens were made by casting. The enamel specimens were prepared from the labial surface of human upper incisor, and the dentine specimens were prepared from the occulusal surface of the human molar respectively. Sound extracted human teeth, which had been kept in a fresh condition since, extraction, were mounted in a wax box with a cold-curing acrylic resin to expose the flattened area. The mounted teeth were then placed in a Specimen Cutter (Technicut) and were cut down under a water spray, and then the flat area on the all specimens were ground by hand with 400 and 600 grit wet silicone carbide paper. Two such specimens were then cemented together face-to-face with freshly mixed cement, and moderate finger pressure was applied to squeeze the cement to a thin and uniform film. All cemented specimens were then kept in a thermostatic humidor cabinet regulated at $23{\pm}2^{\circ}C.$ and more than 95 per cent relative humidity and tested after 24 hours and 1 week. Link chain was attached to each alloy specimen to reduce the rigidity of the jig assembly, and then all the specimens were mounted in the grips of the Instron Universal Testing Machine, and a tensile load was delivered to the adhering surface at a cross head speed of 0.20 mm/min. The loads to which the specimens were subjected were recorded on a chart moving at 0.50 mm/min. The adhesive strength was determined by measuring the load when the specimen separated from the cement block and by dividing the load by the area. The test was performed in a room at $23{\pm}2^{\circ}C.$ and $50{\pm}10$ per cent relative humidity. A minimum of five specimens were tested each material and those which deviated more than 15 per cent from the mean were discarded and new specimens prepared. From the experiments, the following results were obtained. 1) It was found that the adhesive strength of the polycarboxylate cement to all alloys tested was considerably greater than that of the zinc phosphate cement. 2) The adhesive strength of the polycarboxylate cements was superior to the non precious alloys, such as the copper, indium, nickel and chromium alloys, but it was inferior to the precious gold, silver and palladium alloys. 3) Surface treatment of the alloy was found to be an important factor in achieving adhesion. It appears that a polycarboxylate cement will adhere better to a smooth surface than to a rough one. This contrasts with zinc phosphate cements, where a rough helps mechanical interlocking. 4) The adhesion of the polycarboxylate cement with enamel was found superior to its adhesion with dentine.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.4
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• pp.246-251
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• 2012

Purpose: The purpose of the study is to evaluate the effectiveness of anterior segmental osteotomy (ASO) in bimaxillary protrusion (BP) patients by comparison between the mandibular soft and hard tissue changes from orthodontic treatment and ASO. Methods: All 44 patients were diagnosed with BP in Kyung-Hee Medical Center. Orthodontic treatment with teeth extractions were underwent by 23 patients (Group A) and 21 patients underwent ASO (Group B). Mandibular soft and hard tissue changes were measured and evaluated, which were based on the vertical and horizontal reference line in lateral cephalometric radiographs. Statistical significance between the changes and correlation between each measurement were analyzed. Results: The amount of B point movement was lesser than that of the lower incisal tip (LIT) retraction, and LIT was tilted lingually in group A. The posterior movement discrepancy between LIT and B point was insignificant, and the inclination of lower incisor was not changed in group B. The soft tissues, including the lower lip, showed a posterior movement and reduction in the depth of mento-labial groove. According to the correlation analysis, the movement of the lower incisor was significantly related to the movement of the lower lip in group A, and the movement of the lower incisor was significantly related to that of the movement of lower lip, B point and Pog in group B. Conclusion: The orthodontic treatment in BP patients results in posterior tilting movement of the lower incisor, but ASO results in the bodily movement of the lower incisor. Consequently, ASO is more effective in BP cases because it ensures the controlled movement of the lower incisors.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.2
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• pp.200-206
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• 2016

Root fracture is defined as a fracture involving the dentin, cementum, and pulp. Most fractures occur in the maxillary anterior teeth between the ages of 11 and 20 years old. The treatment for root fracture in permanent teeth involves the reduction and fixation of the displaced coronal segment. When signs of pulp necrosis or inflammatory root resorption are present, root canal therapy should be performed. Since most apical fragments maintain pulp vitality, root canal therapy is typically limited to coronal fragments. However, it's too difficult to achieve a proper apical stop on coronal fragment. Intentional replantation involves performing root apex treatment outside the mouth after intentional extraction of the tooth in a controlled environment and then replanting it. The objective is 'perfect' root canal therapy. Intentional replantation may be used in cases of failed typical root canal therapy, problematic endodontic retreatment due to the existing restoration or a calcified root canal, and when apical surgery is contraindicated because of a lack of reasonable approaches. In this case, intentional replantation was carried out to treat a horizontal root fracture in a maxillary central incisor with a calcified root canal due to previous trauma. We achieved a clinically and functionally satisfactory result.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.516-522
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• 2008

In the case of the impacted teeth, the clinician has to consider development of tooth, site of impaction, eruption path, and cooperation of patient. If there are genetic or general factors to effect the eruption of tooth, the clinician treats these first and then takes the early treatment for eruption guidance. If there are physical factors to intercept eruption, the clinician put them off first. However, if there are no factors to effect eruption of tooth and enough space for eruption, the clinician can consider extraction of deciduous teeth, forced eruption and surgical reposition. In case of surgical repositioning, proper time for root development, proper socket formation, and minimal trauma are important for success. This case presents displaced impacted maxillary central incisor with dilacerated root. The development of root is Nolla's stage 7, and the tooth was treated by surgical repositioning. We can observe no root resorption and good healing pattern.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.248-256
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• 2020

This study aimed to evaluate the effects of national dental screening for children in Korea in the aspects of prevention of dental caries, the number of treatments related to dental caries, and cost of dental care. The study used the national cohort data on children health screening provided by National Health Insurance Service, and analyzed 32,937 1st dental screening, 22,608 2nd dental screening, 13,708 3rd dental screening, and 241,043 cases from the dental care of 27,944 children born in year 2008 and 2009. The decayed-filled teeth index and decayed-filled person rate, calculated from the results of the 2nd and 3rd dental screening, decreased as the number of preceding dental screening increased. Glass ionomer and amalgam restoration, pulp treatment of primary teeth and extraction of primary canine and molar were shown to decrease as the number of examined dental screening increased, and the total cost of dental care covered by national health insurance also decreased as the number of dental screening increased. In conclusion, national dental screening for children is an efficient and economical oral health care method that prevents dental caries and lowers the possibility of dental caries related treatment, thereby reducing cost of dental care.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.7 no.1
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• pp.25-28
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• 2011

Autism is a developmental, neuropsychiatric disorder that begins in early childhood. A patient with autism seen in the dental office frequently may have many complications. Therefore, it may be needed to consider modified or alternative therapy for dental care of autistic patients. This is the case of a 16-year old boy who have autism. He came to the department of the pediatric dentistry, Yonsei University Dental Hospital, for evaluation and treatment of dentigerous cyst associated with impacted teeth(#33,34,35). Under daily hospitalization and general anesthesia, the cyst was enucleated with surgical extraction of #34 and autotransplantation of #33,35. And during the periodic dental followup, apexification of #33,35 was performed for periapical lesion and root maturity. At 2 year 6 months follow- up, now, bony healing was completed and there are some complications like external resorption of #33 and space loss of #34 area. Generally, the marsupialization has been widely recommended for treatment of dentigerous cyst. However, in this case, there is a little possibility of spontaneous eruption after marsupialization considering of patient's age, location and angulation of the impacted tooth, root maturity. And there is necessity to choose the treatment that has low recurrence risk and needs short-term follow-up for autism. Above all, poor oral hygiene and lack of cooperation for decompression treatment is a matter of primary consideration. Consequently, enucleation of the cyst was chosen for the final treatment plan in this case. It is important to consider the conditions that affect the eruption of a dentigerous cyst-associated tooth to predict the successful eruption and special health care needs of the patient when the treatment plan is settled.