• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.11-15
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• 1987

Thirty maxillary second premolars were fixed, decalcified, washed and embedded in celloidin to observe the root canal size and morphology at apical 5mm area. The results were as follows: 1. Single canaled teeth and two canaled teeth were approximately equal numbered. 2. Single canaled teeth have round canal but two canaled teeth have long, slender buccal canal and ovoid lingual canal. 3. The canal size of single canaled teeth was $380{\pm}30{\mu}m,\;340{\pm}22{\mu}m$, but that of buccal canal of two canaled teeth was $360{\pm}32{\mu}m,\;240{\pm}28{\mu}m$, lingual canal was $330{\pm}28{\mu}m,\;280{\pm}20{\mu}m$.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.441-447
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• 1996

This study was carried out in order to find out the pattern of the root resorption following maxillary incisor retraction after maxillary 1st bicuspid extration in maxillary protrusion patients. For this study, thirty two patient who received orthodontic treatment were chosen. The results were as follows; 1. Of the total 192 teeth, 61 teeth(31.77%) showed no apical root loss, 64 teeth(33.33%) fell into the class "slight", 46 teeth(23.96%) fell into the class "moderate". Only 21 teeth(10.94%) were classified as "excessive". 2. No correlation was noted between the amount of apical root loss and the types of tooth movement of the maxillary central incisors. 3. The patients who were treated with standard brackets had more changes in tooth axis and less movement of root apexes, but the patients with straight brackets had less changes in tooth axis and more movement of root apexes. 4. Comparing the degree of root resorption between bracket types, patients who had used standard brackets showed more apical root loss than patients who had used straight brackets. 5. The most frequent degree of root resorption observed in standard bracket patients was second degree, followed by first degree and third degree. The most frequent degree of root resorption observed in straight bracket patients was zero degree, followed by first, second degree and third degree.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.222-228
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• 2011

Purpose: The purposes of this study were to evaluate the stress distributions and the displacements of obturator for edentulous maxillectomy patients and to compare them with those of complete denture using three-dimensional finite element analysis. Materials and methods: Based on the CT image of edentulous patient, three-dimensional finite element model of edentulous maxillae was constructed. Three-dimensional finite element model of edentulous maxillae with palatal defect was also fabricated. On each model, complete denture and obturator prosthesis were created. Vertical static force of 200 N was applied on the left maxillary premolar and molar region. The von Mises stress values and the displacements of models were analyzed using three-dimensional finite element analysis. Results: Maximum von Mises stress values were recorded in the cortical bones of both models. The von Mises stress value in the complete denture model was 2.73 MPa and 2.69 MPa in the obturator model. High von Mises stress values were also observed on the tissue surface of prosthesis. The maximum value of the displacement in the obturator was higher than that of complete denture. Conclusion: The obturator showed a worse result in terms of stress distribution and displacement than complete denture. In the prosthodontic rehabilitation of edentulous maxillectomy patient accurate impression procedure based on patients'anatomy and application of prosthodontic principle should be considered.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.647-653
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• 2009

Tooth transposition is an anomaly of eruption characterized by the interchanged positions of two adjacent teeth, which is divided into complete and incomplete transposition. There are three common approaches for treating transposition: aligning the involved teeth in their transposed positions, moving them to their correct anatomic position in the arch and extracting one of the transposed teeth. Considerations in treatment plans are esthetic, function, risk of jeopardizing the roots and damaging the supporting structures, position of the root apex, developmental stages of teeth and expected compliance. The presented case reports described one maxillary canine-the first premolar transposition and two mandibular lateral incisor-canine transpositions. The former transposed teeth were arranged in their transposed position, and the latter transposed teeth were rearranged into their normal position.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.109-115
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• 2006

The calcifying odontogenic cyst (COC) predominantly affected Maxillary anterior segment and it is developmental cyst. But COC showed diverse terminology or classification, clinicopathologic features as well as its biologic behavior COC usually presents as slowly enlarging but otherwise symptomless swelling. Association with impacted teeth and odontoma is described in $24{\sim}30%$. The epithelial lining of COC(ghost cell) appears to have ability to induce the formation of dental tissues in the asjcents connective tissue wall. This case is a COC associated with a odontoma involving an impacted left maxillary canine in 14-year-old female child. Radiographic examination revealed a well-demarcated radiolucent lesion partially occupied by a radiopaque mass, involving the left canine. The histologic sections showed cystic cavity lined with ameloblastic epithelium containing ghost cell masses with regular and irregular shape odontoma. The final pathologic diagnosis was calcifying odontogenic cyst with odontoma(Type IB by Preatorius). Enucleation and elimination of the included tooth were performed. Now endodontic treatment was preformed on the 1st premolar of the upper left jaw, which had a lesion. And the patient and their parents want to have the orthodontic treatment performed and would like to keep the space maintainer.

• The korean journal of orthodontics
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• v.37 no.6
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• pp.421-431
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• 2007

The objective of this study was to provide guidelines for the diagnosis and successful treatment of orthodontic treatment with upper premolar extraction only Methods: The sample group consisted of 40 patients (20 with upper premolar extraction only, 20 with both upper and lower premolar extractions) who showed an overjet of more than 7 mm and were finished successfully. Lateral cephalographs were taken before and after orthodontic treatment. Landmarks showing the position of the upper and lower incisors and the position of the upper and lower lip were determined and angular measurement of these values were obtained for statistical analysis (Mann-Whitney test). Results: At pre-treatment, the position of the lower incisor was less labially inclined and the convexity of the lower lip was smaller in the upper premolar extraction only group than in the upper/lower premolar extraction group. At post-treatment, there was no difference in all measurements except for the position of the lower incisor. A comparison of changes between pre- and post-treatment showed that the retraction of upper & lower incisors and the decrease in convexity of the lower lip were greater in the upper/lower premolar extraction group. Conclusions: Treatment by upper premolar extraction can be of benefit for patients whose lower incisor proclination and lower lip protrusion are not excessive.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.421-430
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• 1997

Alveolar bone grows with development of tooth germs and roots; bone deposition occurs with tooth eruption. Bone components undergoes processes of resorption and deposition, and when the balance between them is disrupted, decrease in alveolar bone height or excessive bone deposition result. It has been hon that repositioning of teeth through orthodontic treatment can cause alveolar bone resorption which result in decreased alveolar bone height, and there have been many studies to evaluate such effects. X-ray films that could be replicated and standardized were chosen in clinical studies, and among them, bitewing films were used for objective evaluation of changes in alveolar bone level. Twenty subjects, 10 to 13-year- old (average 12.2) children with Cl I molar key, healthy oral condition, no congenital missing, no periodontal disease, and pre-and post-orthodontic bitewing films, were randomly selected for comparison of alveolar bone heights. Amounts of tooth and changes in alveolar bone heights were analyzed. The following results were obtained: 1. Amount of tooth movement in canine, premolar, and molar regions, changes in tooth axis, and changes in alveolar bone heights were measured, and the mean and median values were obtained. 2. When pre-and post-orthodontic alveolar bone levels were compared, larger changes were noticed in maxilla than mandible. 3. When mesio-distally compared, larger changes were observed in the distal sides of 3D3 and 4M3, mesial sides of 4M3 and 4D3, distal sides of 4D3 and 5M3, mesial sides of 5M3 and 5D3, md distal sides of 5D3 and 6M3. 4. When the amounts of tooth movements(TX, TY)and changes in tooth axis(A) were compared,34TX, 34TY, 34A of both sides in maxilla were greater, iud changes in alveolar bone level were greater than any other region.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.16-22
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• 2014

Purpose: The purpose of this study was to assess the marginal and mesial fitness of zirconia single copings and 3-unit fixed partial dentures (FPDs) manufactured with an identical model. Materials and Methods: An epoxy model in which the maxillary right 2nd premolar is lost and maxillary 1st premolar and 2nd molar are formed as abutments was manufactured and scanned by using a laser scanner. A ten units of zirconia single copings were manufactured for maxillary 1st premolar and 2nd molar, respectively and the same number of 3-unit FPDs were manufactured. For the measurements of fitness, the manufactured silicone replicas were divided into four parts and the fitness were measured by digital microscope at measurement points (P1, P2, P3, P4 and P5) of each plane. The measured gaps were classified into three categories: marginal gap (MG, P1), axial gap (AG, average of P2 and P3), occlusal gap (OG, average of P4 and P5). Results: The ranges of MG, AG and OG for single copings were 18.47 - 40.54 ${\mu}m$, 39.73 - 73.61 ${\mu}m$ and 116.90 - 134.69 ${\mu}m$, respectively. The ranges of MG, AG and OG for 3-unit FPDs were 45.95 - 87.44 ${\mu}m$, 23.78 - 57.00 ${\mu}m$ and 99.89 - 131.06 ${\mu}m$, respectively. Conclusion: The result of the study shows that the MGs for 3-unit FPDs were higher than those of single copings, though they are within the range of clinical acceptance, indicating that the use of more homogeneous zirconia block and modification of sintering processes are needed to ensure the prevention of increase of gap in 3-unit FPDs.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.249-257
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• 2012

Purpose: This study was designed to help to provide the criteria of the esthetic smile in oromaxillary region on twenties, fifties and sixties. Materials and methods: The facial straight photographs of 33 adults (male 15, female 18, mean age 27.2 years old) and 20 seniors (male 7, female 13, mean age 55.6 years old) in resting and smile position were taken. The measurements and proportion of lip-teeth relation during smile were statistically analyzed, and survey of freshmen and seniors who belong to School of Dentistry, Chonnam National University were taken to select the best esthetic smile among the photographs. Results: In the relationship between the upper lip and the teeth, average smile was the most frequent, and mean of smile line ratio was 1.090 in young group and 0.90 in old group. The correlation between the buccal corridor ratio and exposed teeth count was inversed. At smile, most frequently exposed tooth was the second premolar (63.64%) in young gourp and the first premolar (35.00%) in old group. The correlation between the upper lip change ratio and exposed clinical crown length of maxillary central incisor was inverse, but there was no correlation between the lower lip change ratio and exposed clinical crown length of maxillarycentral incisor. Conclusion: In the result of survey, the students selected the case exposed to the first premolar as the most esthetic smile. The most esthetic smile between full facial photograph and the lip only photograph by the freshmen was different, but that by seniors was identical.

• The korean journal of orthodontics
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• v.32 no.3 s.92
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• pp.155-163
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• 2002

This study was performed to assess the accuracy of computer-based treatment prediction for soft tissue profile using Quick Ceph Image $Pro^{TM}\;&\;Quick\;Ceph\;2000^{TM}$ in bimaxillary protrusion cases. The Ore- and post-treatment lateral cephalograms of 21 female adults treated by low first premolar extraction were imaged and 9 landmarks and 27 specific soft tissue mesurements were digitized for comparing actual treatment results with computer simulations. The results of this study showed that Quick Ceph Image $Pro^{TM}\;&\;Quick\;Ceph\;2000^{TM}$ tends to overestimeate horizontal changes and underestimate vertical changes. In the computer simulation, upper lip showed rolling tendency. The upper lip measurements were disposed to be regular direction hut lower lip measurements were varied case by case even if it was statistically insignificant.