• Journal of the korean academy of Pediatric Dentistry
• /
• v.34 no.1
• /
• pp.140-149
• /
• 2007

Cleft lip and palate are congenital craniofacial malformation. Reconstruction of dental arch in patient with alveolo-palatal clefts is very important, because they have many problems in functions and esthetics. Malnutrition, poor oral hygiene, respiratory infections, speech malfunctions, maxillofacial deformity, and psychological problems may be occured without proper treatment during the long period of management of the cleft lip and palate. So the treatment should be managed with a multidisciplinary approach. Bone grafting is a consequential step in the dental rehabilitation of the cleft lip and palate patient A complete alveolar arch should be achieyed of the teeth to erupt in and to form a stable dentition. And the presence of the cleft complicate the orthodontic treatment. Therefore bone grafting in patients with cleft lip and palate is a widely adopted surgical procedure. Grafted bone stabilizes the alveolar process and allows the canine or incisor to move into the graft site. After the bone grafting, orthodontic closure of the maxillary arch has become a common practice for achieving dental reconstruction without any prosthodontic treatment. Various grafting materials have been used in alveolar clefts. Iliac bone is most widely fovoured, but tibia, rib, cranial bone, mandible have also been used. And according to its time of occurrence, the bone graft may be divided into primary, early secondary, secondary, late secondary. Bone grafting is called secondary when performed later, at the end of the mixed dentition. It is the most accepted procedure and has become part of treatment of protocol A secondary bone graft is performed preferably before the eruption of the permanent canine in order to provide adequate periodontal support for the eruption and preservation of the teeth adjacent to the cleft. In this report, we report here on a patient with unilateral cleft lip and palate, who underwent iliac bone graft. The cleft was fully obliterated by grafted bone in the region of the alveolar process. The presence of bone permitted physiologic tooth movement and the orthodontic movement of adjacent tooth into the former cleft area. Satisfactory arch alignment could be achieved in by subsequent orthodontic treatment.

• Journal of the Korean earth science society
• /
• v.43 no.1
• /
• pp.128-139
• /
• 2022

This study aimed to investigate the tectonic setting of the volcanic edifice at Mt. Baekdu by analyzing petrochemical characteristics of Holocene felsic volcanic rocks distributed in the Baekdusan stratovolcano edifice and summit of the Cheonji caldera rim, as well as Pleistocene mafic rocks of the Gaema lava plateau and Changbaishan shield volcano edifice. During the early eruption phases, mafic eruption materials, with composition ranging from alkali basalt to trachybasalt, or from subalkaline (tholeiitic) basalt to basaltic andesite formed the Gaema lava plateau and Changbaishan shield volcanic edifice, whereas the Baekdusan stratovolcano edifice and Holocene tephra deposits near the summit of the Cheonji caldera comprises trachytic and rhyolitic compositions. Analysis results revealed bimodal compositions with a lack of 54-62 SiO₂, between the felsic and mafic volcanic rocks. This suggested that magmatic processes occurred at the locations of extensional tectonic settings in the crust. Mafic volcanic rocks were plotted in the field of within-plate volcanic zones or between within-plate alkaline and tholeiite zones on the tectonic discrimination diagram, and it was in good agreement with the results of the TAS diagram. Felsic volcanic rocks were plotted in the field of within-plate granite tectonic settings on discrimination diagrams of granitic rocks. None of the results were plotted in the field of arc islands or continental margin arcs. The primitive mantle-normalized spider diagram did not show negative (-) anomalies of Nb and Ti, which are distinctive characteristics of subduction-related volcanic rocks, but exhibited similar patterns of ocean island basalt. Trace element compositions showed no evidence of, magmatic processes related to subduction zones, indicating that the magmatic processes forming the Baekdusan volcanic field occurred in an intraplate environment. The distribution of shallow earthquakes in this region supports the results. The volcanic rocks of the Baekdusan volcanic field are interpreted as the result of intraplate volcanism originating from the upwelling of mantle material during the Cenozoic era.

• The Journal of the Petrological Society of Korea
• /
• v.22 no.2
• /
• pp.83-115
• /
• 2013

Erroneous fission-track (FT) ages caused by an inappropriate calibration in the initial stage of FT dating were redefined by re-experiments and zeta calibration using duplicate samples. Revised FT zircon ages newly define the formation ages of Yucheon Group rhyolitic-dacitic tuffs as Late Cretaceous to Early Paleocene ($78{\pm}4$ Ma to $65{\pm}2$ Ma) and Gokgangdong rhyolitic tuff as Early Eocene ($52.1{\pm}2.3$ Ma). In case of the Early Miocene volcanics, FT zircon ages from a dacitic tuff of the upper Hyodongri Volcanics ($21.6{\pm}1.4$ Ma) and a dacitic lava of the uppermost Beomgokri Volcanics ($21.3{\pm}2.0$ Ma) define chronostratigraphies of the upper Beomgokri Group, respectively in the southern Eoil Basin and in the Waeup Basin. A FT zircon age ($19.8{\pm}1.6$ Ma) from the Geumori dacitic tuff defines the time of later dacitic eruption in the Janggi Basin. Based on FT zircon ages for dacitic rocks and previous age data (mostly K-Ar whole-rock, partly Ar-Ar) for basaltic-andesitic rocks, reference ages are recommended as guides for stratigraphic correlations of the Miocene volcanics and basements in SE Korea. The times of accumulation of basin-fill sediments are also deduced from ages of related volcanics. Recommended reference ages are well matched to the whole stratigraphic sequences despite complicated basin structures and a relative short time-span. The Beomgokri Group evidently predates the Janggi Group in the Eoil-Waeup basins, while it is placed at an overlapped time-level along with the earlier Janggi Group in the Janggi Basin. Therefore, the two groups cannot be uniformly defined in a sequential order. The Janggi Group of the Janggi Basin can be evidently subdivided by ca. 20 Ma-basis into two parts, i.e., the earlier (23-20 Ma) andesitic-dacitic and later (20-18 Ma) basaltic strata.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.45 no.2
• /
• pp.203-214
• /
• 2018

Root resorption of the permanent maxillary incisors can occur due to ectopic eruption of the permanent canines. Severe root resorption threatens the long-term survival of the affected incisors. The aim of the present study was to identify risk factors for root resorption of the maxillary incisors associated with impacted maxillary canines. In the present study, we retrospectively analyzed the Cone-Beam Computed Tomography (CBCT) scans of 65 children and adolescents with ectopically erupting maxillary canines (total of 88 impacted canines). Root resorption of central incisors was significantly associated with the mesiodistal position and root development of the adjacent canine. Root resorption of lateral incisors was significantly associated with sex, age, and the buccolingual and vertical position of the adjacent canine. However, enlargement of the dental follicle was not significantly associated with root resorption of adjacent incisors. Although incisor resorption is difficult to diagnose and predict, our findings suggest that changes in the dental follicles of the erupting maxillary canines do not cause resorption of the adjacent permanent incisors. CBCT should be utilized to ensure early diagnosis of impacted canines and precise evaluation of incisor root resorption.

• Journal of the Korean Geographical Society
• /
• v.47 no.2
• /
• pp.159-178
• /
• 2012

Since the suggestions on the paleo-glacial landforms in and around the northern high mountains of Korean Peninsula by some western and Japanese scientists in the early 1900s, the likelihood of the glacier existence in the Baekdusan over the Quaternary glacial period has been had in common among most of the Korean geomorphologists. In the other meaning, some have cast doubt on the likelihood the paleo-glacier in the Baekdusan because there has been no unequivocal evidences for the glacier such as striation, moraines, except morphologic characteristic landforms possibly related to glacier. Here we show some evidences for the existence of the glacier in the Baekdusan and their cosmogenic $^{36}Cl$ exposure ages over the late Quaternary and would put forward a model on the Quaternary landscape evolution of the Baekdusan, with a focus on the relationship of 1000 AD explosive eruption and the glacial landforms. The exposure ages constrained by cosmogenic $^{36}Cl$ abundances of the col surface of the western slope located below the glacier yield 46~26 ka, which is inphase with the last glacial period. Given all the evidences above, we can draw a conclusion that the glacier existed on the Baekdusan over the late Quaternary and the style of glaciation changed from extensive ice cap through valley glacier to restricted cirque.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.4
• /
• pp.722-727
• /
• 2006

Most of impacted teeth reported are permanent teeth. Impaction of primary tooth caused by primary failure of eruption is rare and the most of impacted primary tooth are second primary molars. The etiology of a primary molar impaction would appear to be a physical barrier, early ankylosis of the tooth, abnormal development of the primary molar germ or malposition of the successor bud. Transposition has been described as an interchange in the position of two teeth within the same quadrant of the dental arch. It is most commonly seen with canine and lateral incisor teeth, but is rarely associated with the primary dentition. The two cases show the transposition of impacted primary molar and the tooth germ of second premolar in their clinical and radiographic examinations. In case 1, lower second primary molar was deeply impacted inferiorly to the tooth germ suspected to be a second premolar. In case 2, impacted all second primary molars were positioned inferiorly to the tooth germs suspected to be the successors. We extracted all second primary molars under general anesthesia and the extracted tooth germs appeared to be second premolars.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.1
• /
• pp.144-150
• /
• 2008

Multimodal cancer therapy including surgery, chemotherapy, and radiotherapy could not only improve the prognosis of malignancy but also reduce the dosage and toxicity of cancer drug for treatment of malignant tumor. The effects of radiotherapy are generally localized, additive, and accumulative, and depend on dosage, site and cell sensitivity. However, in growing individuals, the dental and skeletal sequelae to radiotherapy result in dental or facial abnormalities that are irreversible : arrested root development, disturbances in enamel formation, microdontia, anodontia, altered tooth eruption and mandibular or maxillary hypoplasia. Especially, the teeth which are developing is affected according to the stage. We report three cases of developmental disturbance of permanent teeth after radiotherapy. These children had received radiotherapy for malignant tumor at the age of 3 to 4 years, in which root hypoplasia, short tapered root and early apex closure were observed. For the management of radiation caries and radiotherapy-related teeth, periodic recall check and oral hygiene instruction are required.

• The Journal of the Petrological Society of Korea
• /
• v.15 no.2 s.44
• /
• pp.72-80
• /
• 2006

We report new K-Ar ages of volcanic rocks from Ulleung-do and Dok-do islands located at the middle of the Korea Sea; $3.67{\pm}0.40\sim1.89{\pm}0.29$ Ma for the Dok-do and $8.07{\pm}0.39\sim0.51{\pm}0.07$ Ma for the Ulleung-do. Such ages reveal that igneous activities of both Dok-do and Ulleung-do extend longer than previously reported. It is likely that igneous activity of Ulleung-do started as early as $8.07{\pm}0.39$ Ma which is much older than age known currently, and latest eruption and intrusion of trachyte of Dok-do lasted until $1.89{\pm}0.29$ Ma, which overlaps previously reported igneous activity of Ulleung-do. However, it seems that the main volcano-building stage of Ulleung-do started after 2.7 Ma and igneous activities of Dok-do were finished mostly before then, which suggests that Dok-do was farmed before Ulleung-do in the respect of main stages of volcano-building. Such explanation agrees well with the hypothesis that southeastern seamounts, Dok-do and Ulleung-do were sequentially generated by relatively fixed hotspot.

• The Journal of the Petrological Society of Korea
• /
• v.20 no.4
• /
• pp.231-241
• /
• 2011

Cheolwon Group in the Cheolwon Basin, which lies northwest of the Gyeonggi massif, has been correlated to the Yucheon Group in the Gyeongsang Basin, but its ages and volcanic times are defined to be considerately earlier than the other one. In this study, SHRIMP zircon U-Pb ages were determined from the igneous rocks in the Cheolwon Basin. The mean ages from zircons are $115.0{\pm}1.1Ma$ in rhyolite, and $111.24{\pm}0.85Ma$ and $109.1{\pm}1.1Ma$ in granite porphyry. The minimum age is 113 Ma in the Jijangbong Tuff. Such age in the rhyolite define the intrusion time of ring dykes, suggesting a caldera collapse following eruption of the Dongmakgol Tuff. Such age in the Jijangbong Tuff represent latest volcanism as postcaldera in the basin. The volcanic rocks in the basin were erupted during late Aptian, and are correlated to the Sindong Group in the Gyeongsang Basin. The plutonism in the basin occurred during $111.24{\pm}0.85Ma{\sim}109.1{\pm}1.1Ma$, following the volcanism. The age distribution of the analyzed zircons in the Jijangbong Tuff indicates the presence of foreign zircons derived from protoliths, regarding a wide span of zircon ages from Cretaceous to Jurassic, Triassic, early and late Protozoic, and Archean. The Archean age suggests the possible presence of the Archean protoliths with such age, which have not been exposed on the surface. The age distribution with wide span suggests that its vent is located in an area that several strata with different ages piled up and intercepted with some intrusives.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.41 no.4
• /
• pp.328-334
• /
• 2014

Gingival fibromatosis is a rare oral condition that is characterized by proliferative fibrous overgrowth of the attached gingiva, the marginal gingiva, and the interdental papilla, typically presenting in the growth period. A case of a 27-month-old girl with a generalized severe gingival overgrowth is described herein. The patient had no known systemic disease, but enlarged gingival tissue had gradually covered her teeth. The excess gingival tissue was removed by conventional gingivectomy, which involved extraction of the retentive primary teeth under general anesthesia when she was 5 years old. Post surgical follow-up at 18 months after the surgery demonstrated no recurrence. Resectional surgery of the enlarged gingival tissue is the treatment choice for gingival fibromatosis, although there is a high risk of recurrence. More frequent professional follow-ups and oral hygiene instruction might be required. A delay in the surgical treatment may have significant consequences for the patient, such as primary dentition retention and consequent delay in the eruption of the permanent teeth, difficulties in mastication and phonation, malpositioning of the teeth, and psychological problems. Early surgical treatment should be performed according to the severity of enlargement.