• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.250-254
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• 2007

Dentigerous cysts are the most common type of developmental odontogenic cysts. They form as a result of a separation of the follicle from around the crown of an unerupted tooth. Usually this lesion can be asymptomatic. Such cysts are often discovered accidently on inspection of x-rays. In other advanced cases, cortical bone expansion, displacement of teeth, secondary infection can be observed. The treatment of dentigerous cyst is enucleation. And according to size, location of lesion and environmental structure marsupialization can be considered. However, Marsupialization takes long treatment time and, cystic tissues are remained so secondary surgery may be needed for total removal., Risks of oroantral fistula, damage on maxillary sinus wall and infraorbital nerve can be considered as complications of conventional surgical treatment of cysts located in maxillary sinus. We treated third molar origin dentogerous cyst located in maxillary sinus removing endoscopically both the tooth and an associated dentigerous cyst. We report our clinical experience with literature review.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.14 no.1
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• pp.89-98
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• 1984

The purpose of the present study is to offer the fundamental materials for the diagnosis of dentigerous cyst by analysis of the clinical and radiographic findings of these lesions. The subject for this study consisted 118 patients admitted to the Department of Oral Radiology, Kyung Hee University and Seoul National University from 1974 to 1983. Conclusions from this study were as follows: 1. There was a higher incidence in males (70.34%) than in females (29.66%), and the incidence was highest in the second and third decade (26.27%) with the same incidence. (Average age: 25 year) 2. There was a higher incidence in the maxillary teeth (66.10%) than in the mandibular teeth (33.90%) and the maxillary supernumerary tooth (45.76%) was the most frequently involved one. The mandibular third molar (16.10%) was next in order of frequency of involvement followed by maxillary canine (7.63%), mandibular second premolar (5.08%). 3. There was a greater incidence of the central type than the lateral type in the maxilla, while a higher incidence of the lateral type in the mandible. 4. There was a greater incidence of the smooth type (84.26%) than that of the scalloped type (15.74%) and a higher incidence of minor type (70.91%) than the major type (29.09%) in the displacement of associated tooth. 5. Root apices of teeth encompassed or approached by the cysts showed variable resorption in 68.47% of cases.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.51-60
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• 2006

Gingival recession is clinically manifested by an apical displacement of the gingival tissue and dentin hypersensitivity is often used to describe a painful condition in which exposed dentin is unduly sensitive to intraoral stimuli. The objects of this study were primarily to investigate the prevalence and distribution of gingival recession and hypersensitivity and secondarily to determine whether a relationship exists between gingival recession and hypersensitivity. The study population was 195 patients (102 males, 93 females) who were attended the department of periodontology, Pusan National University Hospital. 189 patients exhibited gingival recession at least more than 1 tooth, the prevalence was 96.9%. The maxillary and mandibular first premolar and mandibular incisors had the highest prevalence. The majority of patients (139 patients, 71.3%) were diagnosed as having dentin hypersensitivity. Dentin hypersensitivity was determined to 3 seconds application of cold air to the exposed root surface after isolating the test tooth and was commonest in maxillary and mandibular first premolars and mandibular incisors. Relationship between recession and hypersensitivity was analyzed using chi-square test (p=0.05), significant relation (p=0.000) was existed. Gingival recession was more severe, the prevalence of hypersensitivity was higher.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.237-248
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• 1993

Although pantograph has been used to investigate whether the determinents of the mandibular movement were possible contributing factors of TMJ click, there was the problems to understand the role of tooth morphology upon the occurrence of click because of using appliance without tooth contacts. There Were advantages to evaluate the effects of tooth morphology upon the mandibular movements, because intraoral tracing device(Functiograph$^{(R)}$) had been obtained maintaining occlusal contact between the upper and lower natural teeth during mandibular movement. The purpose of this study was to record the mandibular eccentric movement quantitatively performed in 20 adult control subjects and 20 adult subjects with TMJ click and to investigate the effects of occlusion upon the occurrence of TMJ click. The obtained results were as follows : 1. The average ICP-P distance was $3.07{\pm}0.73mm$ in subjects with TMJ click, $2.14{\pm}0.85mm$ in control subjects. There was a statistical significance between subjects with TMJ click and control subjects(P<0.001). 2. The average ICP-P distance was $3.07{\pm}1.14mm$ in subjects with TMJ click, $2.61{\pm}0.96mm$ in control subjects. There was a statistical significance between subjects with TMJ click and control subjects(P<0.05). 3. The average distance of right and left lateral movement was not statistically significant between subjects with TMJ click and control subjects. 4. The average lateral displacement from midline during RCP was $0.75{\pm}0.54mm$ subjects with TMJ click, $0.16{\pm}0.17mm$ in control subjects. There was a statistical significance between subjects with TMJ click and control subjects(P<0.001). 5. The average lateral displacement from midline during protrusive movement was $0.88{\pm}0.54mm$ in subjects with TMJ click, $0.20{\pm}0.23mm$ in control subjects. There was a statistical significance between subjects with TMJ click and control subjects(P<0.001). 6. The average angle of right and left lateral movement was $144.2{\pm}20.20^{\circ}$ in subjects with TMJ click, $138.15{\pm}20.09^{\circ}$ in control subjects. There was a statistical significance between subjects with TMJ click and control subjects(P<0.05).

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.1
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• pp.77-82
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• 2011

A long-term follow-up study of a case of impacted teeth associated with a large dentigerous cyst in the left maxilla is presented. The patient was a 30-year-old man who had a large dentigerous cyst in the premaxilla and left posterior maxilla, which impacted the canine and supernumerary tooth. This is one of the most prevalent types of odontogenic cysts associated with an erupted or developing tooth, particularly the mandibular third molars. The other teeth commonly affected in order of frequency are the maxillary canines, maxillary third molars and rarely, the central incisor. Radiographically, the cyst appears as huge ovoid well-demarcated unilocular radiolucency with a sclerotic border and causes ectopic displacement of the inferior border of the maxillary sinus without destruction. Dentigerous cysts may grow unnoticed to such extensive sizes as to occupy a considerable portion of the maxillary sinus. These cysts appear to be associated with a supernumerary tooth in the maxillary anterior incisors region called the mesiodens and impacted canine. The present case report describes the surgical enucleation of a dentigerous cyst involving the permanent maxillary left canine and mesioden. After surgery, left maxillary sinus recovered their normal size and apposition of bone was observed around the apex of the posterior teeth. During the subsequent years, there was no recurrence of the cystic lesion but the inflammation was evoked in the anterior maxilla after 42 months. This complication appeared to have correlated with bony healing in the enucleation site of the cyst. We report the healing status of a huge dentigerous cyst in the maxilla for 5 years with a review of the relevant literature.

• Imaging Science in Dentistry
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• v.40 no.3
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• pp.109-114
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• 2010

Purpose : This study was performed to analyze the position, pattern of impacted mesiodens, and their relationship to the adjacent teeth using Dental cone-beam CT. Materials and Methods : Sixty-two dental cone-beam CT images with 81 impacted mesiodenses were selected from about 2,298 cone-beam CT images at Chonnam National University Dental Hospital from June 2006 to March 2009. The position, pattern, shape of impacted mesiodenses and their complications were analyzed in cone-beam CT including 3D images. Results : The sex ratio (M : F) was 2.9 : 1. Most of the mesiodenses (87.7%) were located at palatal side to the incisors. 79% of the mesiodenses were conical in shape. 60.5% of the mesiodenses were inverted, 21% normal erupting direction, and 18.5% transverse direction. The complications due to the presence of mesiodenses were none in 43.5%, diastema in 19.4%, tooth displacement in 17.7%, delayed eruption or impaction in 12.9%, tooth rotation in 4.8%, and dentigerous cyst in 1.7%. Conclusions : Dental cone-beam CT images with 3D provided 3-dimensional perception of mesiodens to the neighboring teeth. This results would be helpful for management of the impacted mesiodens.

• Imaging Science in Dentistry
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• v.40 no.3
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• pp.115-121
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• 2010

Purpose : The purpose of this study was to accurately analyze the radiographic characteristics of dentigerous cyst (DC) with multiplanar images of cone beam computed tomography (CBCT). Materials and Methods : Thirty eight radiographically and histopathologically proven cases of DCs were analyzed with panoramic radiograph and CBCT, retrospectively. The radiographic CT pattern, symmetry of radiolucency around the unerupted tooth crown, ratio of long length to short length, degree of cortical bone alternation, effects on adjacent tooth, and cyst size were analyzed. Relative frequencies of these radiographic features were evaluated. In order to compare the CBCT features of DC with those of odontogenic keratocyst (OKC), 9 cases of OKCs were analyzed with the same method radiographically. Results : DCs consisted of thirty unilocular cases (79.0%), seven lobulated cases (18.4%) and one multilocular case (2.6%). Eight were asymmetric (21.0%) and thirty were symmetric (79.0%). Maxillary DC showed rounder shape than mandibular DC (L/S ratio; maxilla 1.32, mandible 1.67). Alternations of lingual cortical bone (14 cases, 48.2%) were more frequent than those of buccal side (7 cases, 24.1%). CBCT images of DC showed definite root resorption and bucco-lingual tooth displacement. These findings were hardly observed on panoramic radiographs of DCs. Comparison of CBCT features of DC with those of OKC showed several different features. Conclusions : CBCT images of DC showed various characteristic radiographic features. Therefore, CBCT can be helpful for the diagnosis of DC radiographically.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.401-411
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• 2002

Precise bracket positioning is essential in modem orthodontics. However, there can be alterations in the vertical position of a bracket due to several reasons. The purpose of this study was to evaluate the effect of variations in the vertical bracket position on the crown inclination in Korean patients with normal occlusion. From a larger group of what was considered to be normal occlusions obtained from the Department of Orthodontics, College of Dentistry, Seoul National University, each of the final 10 subjects (6 males and 4 females, with an average age of 22.3 yews) was selected. The dental models of each of the subjects were scanned three-dimensionally by a laser scanner, and measurements drawn from these were made on the scanned dental casts of the subjects were input into the computer program. From this the occlusal plane and the bracket plane were determined. The tooth plane was then constructed to measure the crown inclination on the bracket plane of each tooth. From a practical standpoint, information was obtained on the extent to which the torque of a tooth would be changed as the bracket position was to be moved vertically (in ${\pm}0.5mm,\;{\pm}1.0mm,\;{\pm}1.5mm$) from its ideal position. A one way analysis of the variance (ANOVA) was used to compare each group of the different vertical distances from the bracket plane on a specific tooth. Duncan's multiple comparison test was then performed. There were statistically significant differences in the crown inclination among the groups of different vertical distances for the upper central incisor, upper lateral incisor, upper canine, upper first and second molars, lower first and second premolars, and lower first and second molars (p<0.05). On the upper anterior teeth, upper molars, lower premolars and lower molars, the resultant torque values due to the vertical displacement of the bracket were different depending on the direction of the displacement, occlusal or gingival. This study implies that the torque of these teeth should be handled carefully during the orthodontic treatment. In circumstances in which the bracket must be positioned more gingivally or occlusally due to various reasons, it would be useful to provide the chart of torque alteration of each tooth referred to in this study with its specified bracket prescription.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.750-756
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• 2008

Supernumerary teeth are frequently found in the anterior portion of the maxilla and develop as a result of abnormal proliferation of the dental lamina during tooth germ formation, caused by genetic or environmental factors. They may result in various complications, such as eruption interference, displacement, rotation of adjacent teeth, diastema, eruption into the nasal cavity, and development of dentigerous cyst. The optimal time for surgical extraction of supernumerary teeth has been a controversial issue. Someone prefer early surgical extraction because supernumerary teeth can cause eruption interference and displacement of adjacent teeth, eventually altering occlusion. Others prefer to delay surgical extraction until $8{\sim}10$ years of age in consideration of root maturation of the adjacent teeth and also patient's behavior. When surgical extraction of supernumerary teeth is postponed, there is possibility that impacted supernumerary teeth in the inverted or horizontal position move toward the nasal cavity, hard palate, or premolar area. When such intraosseous tooth migration is combined with the vertical growth of the maxilla, surgical approach becomes even harder. Therefore, possibility of intraosseous tooth migration should be considered as an important factor when deciding appropriate time for surgical extraction. We are presenting cases of mesiodens which showed intraosseous migration during $6{\sim}7$ years of follow-up period since the first diagnosis had been made at the $2{\sim}3$ years of age.

• 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.