• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.34-40
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• 2004

Unerupted maxillary anterior teeth is not a common case, However it may present practitioners with management problem. The cause of impaction is considered to be multifactorial, and local cause is the most common. These impacted teeth require surgical intervention, removal, transplantation, or surgical exposure, with or without orthodontic traction to align the malpositioned tooth. The preferred option is surgical exposure and orthodontic correction. Surgical intervention and orthodontic correction should not be delayed to avoid unnecessary difficulties in aligning the tooth in the arch. Surgical exposure should be performed with the intent of providing sufficient attached gingiva rather than simply uncovering the crown, which results in only alveolar mucosal attachment. Attached gingiva is essential to secure the gingival tissues to the adjacent teeth at the dentogingival junction. Thus preventing loss of periodontal tissues as a result of the pull of the surrounding soft tissues and facial muscles. Labially impacted maxillary anterior teeth uncovered with an apically positioned flap technique have more un- esthetic sequelae than those uncovered with a closed-eruption technique. In the case of severly displaced impacted teeth, autotransplantation ensures preservation of the alveolar bone and will facilitate future placement of an osseointegrated implant once growth has ceased or if ankylosis/resorption of the transplant occurs.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.273-285
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• 2000

The aim of this investigation was to evaluate the differences of two canti-leyer springs by using a new simulation system. This was done using a Calorific machine that compared iron uprighting spring and root uprighting spring. The Calorific machine was designed to allow observation of the whole process of tooth moving, and is composed of three parts(a temperature regulating system, electro-thermodynamic teeth, and an artificial alveolar bone component). The experiment of both mechanics were repeated five times and measured two times. The intra-examiner agreement and inlet-examiner agreement were $96.54\%\;and\;95.73\%$ and these data were statistically tested by paired t-test. The obtained results were as follows. 1. Distal and buccal movement of the anchor teeth were observed greater in the root uprighting spring than the crown uprighting spring. 2. Crown uprighting spring showed distal movement of the crown of lower second molar for 3.29mm but root uprighting spring showed only 1.68mm. 3. Crown uprighting spring exhibited forward movement of mesial and distal root of the lower second molar for 3.91mm, 3.60mm but the root uprighting spring showed 6.76mm, 6.26mm.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.1-13
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• 2001

The extraction lot orthodontic treatment can be adopted for aligning crowded dentition, improving facial esthetics and solving a skeletal discrepancy as alternative for a surgical option. Mandibular second premolar extraction was often selected as treatment plan when there we very little or no space shortage in lower arch or limited retraction of the lower incisors was required. The primary object of this study was evaluate a pretreatment condition and examine the amount of tooth movement ior a mandibular second premolar extraction in growing patients. Pretreatment and posttreatment lateral cephalograms of 14 cases that had their four first premolar extracted (4/4 group), 15 cases with upper first and lower second premolar extraction (4/5 group) were selected. Structural method superimposition was conducted to evaluate a difference of dental change between 4/4 and 4/5 group. The results were as follows, 1. Pretreatment factor for 4/4 extraction or 4/5 extraction choice included maxillary incisor axis to occlusal plane, Class II molar relationship, IMPA and interincisal angle. 2. The amount of molar anterior movement in 4/5 group was greater than that of 4/4 group(p<0.05). 3. There was no significant difference between 4/4 group and 4/5 group in aspects of maxillary tooth movement(p<0.05).

• International Journal of Oral Biology
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• v.36 no.3
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• pp.117-122
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• 2011

Endothelial cells are a vital constituent of most mammalian organs and are required to maintain the integrity of these tissues. These cells also play a major role in angiogenesis, inflammatory reactions, and in the regulation of thrombosis. Angiogenesis facilitates pulp formation and produces the vessels which are essential for the maintenance of tooth homeostasis. These vessels can also be used in bone and tissue regeneration, and in surgical procedures to place implants or to remove cancerous tissue. Furthermore, endothelial cell regeneration is the most critical component of the tooth generation process. The aim of the present study was to stimulate endothelial regeneration at a site of acute cyclophosphamide (CP)-induced endothelial injury by treatment with human umbilical cord-derived endothelial/mesenchymal stem cells (hEPCs). We randomly assigned 16 to 20-week-old female NOD/SCID mice into three separate groups, a hEPC ($1{\times}10^5$ cells) transplanted, 300mg/kg CP treated and saline (control) group. The mice were sacrificed on days 5 and 10 and blood was collected via the abdominal aorta for analysis. The alanine transaminase (ALT), aspartate aminotransferase (AST), serum alkaline phosphatase (s-ALP), and albumin (ALB) levels were then evaluated. Tissue sections from the livers and kidneys were stained with hematoxylin and eosin (HE) for microscopic analysis and were subjected to immunohistochemistry to evaluate any changes in the endothelial layer. CP treatment caused a weight reduction after one day. The kidney/body weight ratio increased in the hEPC treated animals compared with the CP only group at 10 days. Moreover, hEPC treatment resulted in reduced s-ALP, AST, ALT levels compared with the CP only group at 10 days. The CP only animals further showed endothelial injuries at five days which were recovered by hEPC treatment at 10 days. The number of CD31-positive cells was increased by hEPC treatment at both 5 and 10 days. In conclusion, the CP-induced disruption of endothelial cells is recovered by hEPC treatment, indicating that hEPC transplantation has potential benefits in the treatment of endothelial damage.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.535-539
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• 2000

Ectopic eruption of a tooth into the oral environment occurs commonly whereas ectopic eruption of a tooth into other sites is rare. Those that have been reported include the nasal cavity, chin, mandibular condyles, coronoid processes, orbits and maxillary sinus. The etiologic factors of ectopic eruption are developmental disturbances such as cleft palate and teeth displaced by trauma or cysts, maxillary infection, genetic factors, crowding and exceptionally dense bone. In many cases, however, the etiology cannot be identified. Eruption of the teeth into the maxillary sinus is uncommon, however the identification of such teeth can be important since they have the potential to cause considerable morbidity. The definitive treatment is surgical removal of the teeth. A 7 year-old-boy visited the Department of Pediatric Dentistry, College of Dentistry, Yonsei University for treatment of dental caries. The abnormal erupting paths of the left and right maxillary canines were found during routine panoramic radiographic investigations. A panoramic radiograph taken at 13 years old revealed that two maxillary canines were located into the sinus. The teeth were extracted by the Caldwell-Luc approach.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.4
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• pp.409-415
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• 2019

Cleidocranial dysplasia (CCD) is an autosomal-dominant disease characterized by the delayed closure of cranial sutures, defects in clavicle formation, supernumerary teeth, and delayed tooth eruption. Defects in the Runt-related transcription factor 2 (RUNX2), a master regulator of bone formation, have been identified in CCD patients. The aim of this study was to identify the molecular genetic causes in a CCD family with delayed tooth eruption. The 23-year-old female proband and her mother underwent clinical and radiographic examinations, and all coding exons of the RUNX2 were sequenced. Mutational analysis revealed a single nucleotide deletion mutation (NM_001024630.4 : c.357delC) in exon 3 in the proband and her mother. The single C deletion would result in a frameshift in translation and introduce a premature stop codon [p.(Asn120Thrfs^*24)]. This would result in the impaired function of RUNX2 protein, which may be the cause of delayed eruption of permanent teeth in the family.

• Journal of Life Science
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• v.17 no.11
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• pp.1488-1491
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• 2007

An epulis was occurred on gingiva of 11-year old female dog, Yorkshire terrier. Our case had feature of ossifying epulis but there were a few multi-nucleated giant cells (MGCs). MGCs had osteoclast-like appearance and giant cell epulis usually appears at the site of tooth extraction. Therefore, we suggest that appearance of MGCs in our case may be due to phagocytosis pre-formed osteoid/bone or our case may be mixed epulides of ossifying and giant cell epulis by mixed stimulation of chronic gingivitis and trauma and in flammation by tooth extraction. Thus, MGCs have possibility enough to appear in ossifying epulis, but ossifying epulis accompanying MGCs has not been reported. Therefore, our case may deserves an attention as an unique case and will be helpful to study pathogenesis of giant cell containing lesion of the jaw.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.277-285
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• 2001

Periodontal disease is characterized by inflammation and subsequent loss and/or damage to tooth-supporting tissues such as bone, cementum,and periodontal ligament. Periodontal ligament and cementum are the key tissues in the initial process of regeneration following periodontal disease. Therefore, studies on cementoblasts, which form cementum are emphasized. It is still unclear which cells cementoblast differentiate from. This study was conducted under the hypothesis that PDL fibroblast can differentiate into either cementoblast or osteoblast depending on the conditions of surrounding tissue. Clinically, with excessive traction force of orthodontic appliances or excessive occlusion hypercementosis is observed, and this has been confirmed histologically. Consequently, activation of cementoblast can be expected in rats when mechanical stimuli are given to PDL fibroblast. Therefore, the purpose of this article is to prove that PDL fibroblast differentiates into cementoblast in rats under mechanical stimuli using histologic and molecular methods. In this study, twenty rats were given hard diet. Ten of them were sacrificed after 1 week, and the others were sacrificed after two weeks. Slides were made from tooth specimen, and they were studied under the microscope. In addition, PDL fibroblast and cementum from the extracted teeth were analyzed with Northern blotting. In histologic examination, as time passed, PDL fibroblast migrated to the dentin side, differentiated into cementoblast, and formed new cementum. In Northern blotting, it was found that mRNA expression of cementoblast-specific proteins such as BSP, OC, OPN, and type I collagen were more prominent in rats sacrificed after 2 weeks of hard-diet than rats sacrificed after 1 week. From these findings we can conclude that PDL fibroblast can differentiate into cementoblast under mechanical stimuli. We think that 'Rat Models' used in this study will be beneficial to future studies regarding cementoblast.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.252-260
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• 2013

Purpose: After the introduction of concept of osteointegration, dental implantology have been successful procedure in the dental field. Recently, it has shown successful results when used to restore single tooth missing. Considering the difference in bone quality of the mandible and maxilla, and the increased occlusal force in the posterior region, the success rates in each region may be different. In this study, success rates of single implants placed in the mandibular first and second molar areas were analyzed. Materials and methods: The subjects were patients (284 patients, 308 implants) who had been operated with single implant installation from 2002 to 2009 in seven dental clinics in Daegu city. One hundred sixty eight implants were placed in the mandibular 1st molar and 140 implants were placed in the mandibular 2nd molar. They were analyzed according to implant site, age, sex, length and diameter. Results: The survival rates of single implant of this study were 97.6% in the mandibular 1st molar and 92.9% in the mandibular 2nd molar. In the mandibular 1st molar, 4 implants were failed. In the mandibular, 2nd molar, 10 implants were failed. Conclusion: The restoration of the mandibular 1st molar using single implant was found to be clinically acceptable treatment and showed higher survival rate than mandibular 2nd molar single implant. Single implant in mandibular 2nd molar needs careful consideration of poor bone quality, risk of overloading and anatomical structure of the mandible.