• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.393-403
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• 1991

The purpose of this study was to evaluate the incidence and radiographic features of 1,300 cases of supernumerary teeth by means of the analysis of periapical radiograms and/or pantomograms in 69,442 persons visited the Department of Oral Radiology, School of Dentistry, Kyung Hee University during January 1980 to December 1989. This study of supernumerary teeth revealed the following features: 1. The incidence of supernumerary tooth was revealed to be 1.5% in total examined persons, and there was a higher incidence in males (74.0%) than in females (26.0%). 2. The supernumerary teeth were most frequently occurred in the 1 st decade (42.7%), followed by the 2nd decades (20.2%), the 3rd decades (14.1 %), and the 5th decades (7.2%). 3. There was a higher incidence in the maxilla (98.7%) than in the mandible (1.3%), and mesiodens (90.1 %) was the most frequently occurred. The maxillary lateral incisor region (3.1%) was next in order of frequency followed by maxillary distomolar (2.2%), and maxillary paramolar (1.5%). 4. There was a higher incidence of the impaction (82.7%) than that of the eruption (17.3%), and supernumerary tooth in lateral incisor region (87.8%) was the most frequently impacted one. 5. The inverted impaction was occurred in 63.1%, the vertical impaction in 18.1%, and the angulated impaction in 18.8%. In localization, a palatally (lingually) impacted supernumerary tooth was occurred in 85.0%, and middle impacted and buccally (labially) impacted supernumerary tooth showed the same incidence (7.5%). 6. A supplemental tooth was occurred in 3.2%, an accessory tooth in 96.8%, and a supplemental tooth was the most frequently occurred in maxillary lateral incisor and mandibular premolar region. 7. In effects of supernumerary tooth on adjacent tooth, crowding was occurred in 0.4%, diastema in 10.6%, rotation in 5.4%, eruption disturbance in 4.5%, root resorption in 2.5%, and dentigerous cyst in 2.2%.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.4
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• pp.630-635
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• 1999

Transposition has been described as an interchange of position of permanent tooth and is a relatively rare dental anomaly. Transposition of teeth may occur both in the maxillary and mandibular arches. but it appears more often in the maxilla of individual teeth, the maxillary canine is the most often involved. A canine transposes most often with a first premolar and less frequently transposes with a lateral incisor. Incomplete transposition is a condition describing an interchange in the position of the crowns of two permanent teeth, while the root apices remain in their relative position. Complete transposition is a situation in which both the crowns and entire root structure are transposed. The etiologic factors of transposition are tooth buds interchange, retained deciduous canines, migration of the erupting canine, trauma to deciduous teeth etc. This report describes a case of a transposition between a maxillary left canine and a lateral incisor and impaction of a maxillary left central incisor due to trauma to deciduous dentition.

• Analytical Science and Technology
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• v.36 no.2
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• pp.99-104
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• 2023

Trace elements (TEs) have significant effects on both dental health and human health. Toxic effects are caused by deficiency or excess of TEs. This study was performed to determine levels of toxic and trace elements in incisor and molar teeth sampled from male and female participants residing in the north and south regions of Sudan. The tooth enamel of 18 extracted human teeth was analyzed using particle-induced x-ray emission (µ-PIXE) to determine its elemental profile and distribution. GeoPIXEII software package was used for the analysis of µ-PIXE data. The main elements determined were Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Zn, Co, and Sr which were homogeneously distributed in the areas of the tooth enamel mapped with micro-PIXE.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.103-117
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• 1981

The data about dental caries obtained from 1438 preschool children (male 797, female 641) in Seoul aged from 3 to 6 were analyzed by their sexes, ages, jaws and teeth surfaces. The results were as follows. 1. dmf rate : 92.63% 2. dmft index : 6.06 dmft rate 30.81 % dmfs index : 11.82 dmfs rate 12.02 % 3. d,m & f rate d rate: 79.45% m rate: 8.15% f rate : 12.40 % 4. dft index : 5.94 5. The order of caries susceptible tooth 1. Lower deciduous 2nd molar 2. Lower deciduous 1st molar 3. Upper deciduous 2nd molar 4. Upper deciduous lateral incisor 5. Upper deciduous cental incisor 6. Upper deciduous lateral incisor 7. Lower deciduous canine 8. Upper deciduous canine 9. Lower deciduous central incisor 10. Lower deciduous lateral incisor 6. Predilection sites of each tooth A) Deciduous central incisor ; Max. : Mesial cavity Mand. : Mesio-distal cavity B) Decidous lateral incisor ; Max. : Mesial cavity Mand. : Distal cavity=Mesial cavity C) Deciduous canine; Max. : Labial cavity Mand. : Distal cavity D) Decidous 1st molar ; Max. : Disto-occlusal cavity Mand.: Disto-occlusal cavity E) Deciduous 2nd molar ; Max. : Linguo-occlusal cavity Mand.: Occlusal cavity 7. All the values in caries criteria in 1981 were somewhat lower than in 1968, but m & f rate were increased.

• Restorative Dentistry and Endodontics
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• v.26 no.2
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• pp.180-187
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• 2001

The structure of current guides is largely illogical and without any rational use of color ordering. The shade guides are generally made of plastic (rather than the actual composite material) and do not accurately depict the true shade. translucency. or opacity of the composite resin after polymerization. To solve this problem, information based on evaluations of natural teeth and material that use the same method and experimental conditions is necessary. The present investigation measured the color of natural maxillary anterior teeth in vivo and compared the results with those of composite resins. 269 Korean subjects were selected for this study. Intact central incisor. lateral incisor. and canine were selected. The clinical crowns were free of caries or restorations. The middle site of the coronal portion on the labial surface of the tooth was measured by Chroma Meter. The five light activated. resin-based materials (Amelogen, Denfil, Elitefil, Spectrum, Z100) were used in this study. Resin composite was condensed into plastic mold with a diameter of 8mm and a thickness of 4mm. pressed between glass plates to flatten the surfaces. and polymerized using a Visilux II visible light activation unit. The surfaces were polished sequentially on wet sandpaper. Color measurements of each specimen were accomplished by Chroma Meter. A computer program that compares each tooth color with each composite resin color was written and the minimum CIELAB color difference ($\Delta$E$^*$) between tooth and each material was calculated. Under the conditions of this study: 1. Teeth tend to become darker with advancing age. 2. Canines were darker. more yellow. and less green than incisors. 3. The teeth from the women were lighter. more green. and less yellow than the male teeth. 4. In general. composite resins were lighter. more green. and less yellow than teeth. Deficiencies were noted in Hues in YR range. 5. Mean color differences between the five composite resin products and teeth were detectable to the naked eye($\Delta$E$^*$>1.0). 6. In comparing the mean $\Delta$E$^*$ values of materials. Spectrum showed the least followed by Z100, Elitefil, Amelogen, Denfil in increasing order.

• Journal of Korean Dental Science
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• v.16 no.1
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• pp.23-34
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• 2023

Purpose: This study aims to investigate the force delivery profile of thermoformed aligners (TFA) compared with direct-printed aligners (DPA) and to explore the effect of different activation amounts on forces and moments of respective groups. A secondary objective is to observe the amount of stress relaxation that occurs over the 7~14 days when aligners are maintained in a simulated intraoral environment. Materials and Methods: An in vitro setup was created to quantify forces and moments. It consisted of a three dimensional-printed base plate and segmented maxillary teeth, placed in a semi-enclosed chamber to maintain a temperature of 37℃. Ninety clear aligners were divided into nine groups of ten aligners each based on material types (Zendura, ATMOS, TC-85) and activation amounts. Aligners were created with 0.00, 0.25- and 0.50-mm activations for lingual bodily movement of the upper left central incisor and kept on models in the "stressed" position in a 37℃ water bath. Three force components acting on the upper left lateral incisor, upper left central incisor, and upper right central incisor were measured for each time point, beginning from the initial baseline measurement, 8 hours, 16 hours, 24 hours, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, and lastly, 14 days. Result: TC-85 aligners in every activation group showed less force on teeth than Zendura and ATMOS. Significant force levels from 0.0 mm activation were present and stayed consistent over the course of 14 days. Comparisons made for baseline measurements to 7-days and 14-days showed statistically significant change from the baseline force level. Conclusion: TC-85 aligners demonstrated lower, more consistent forces with fewer side effects. Aligners can generate forces even when no activation is programmed. No major decreases in force levels over time were observed; the intra-oral clinical simulated environment and length of observation time could contribute to this.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.580-585
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• 2009

Pediatric dentists often meet children with abnormal in number of tooth. Presence of supernumerary teeth is frequent cause of malocclusion. Etiology for supernumerary teeth is not yet clearly defined, but it is thought to be caused by excessive proliferation of dental lamina by hereditary and environmental factors. Supernumerary teeth occur in the maxilla nine times more frequently than in the mandible. Most common supernumerary tooth is the mesiodens in the maxilla, and some are observed in the maxillary molar and mandibular premolar. It occurs rarely in the mandibular incisor region with the incidence of 1-2% among all supernumerary teeth. A six-year old boy visited the department of the pediatric dentistry, Yonsei University Dental Hospital, with the chief complaint of crowded supernumerary teeth on the mandibular incisor region. Clinical and radiographic examinations revealed six permanent mandibular incisors similar in size, shape, and length. Further investigation using computed tomography(CT) was proceeded on the mandible to measure and compare morphologic features and positions of the six incisors. Then, we decided to remove two incisors which were already erupted. Periodic check-up was followed to monitor the dental development and spontaneous positional enhancement of the remaining four incisors in the mandible.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.576-580
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• 2003

A 7-year-old male was refered to Department of Pediatric Dentistry, Wonkwang Dental Hospital for treatment of a traumatic injury to the teeth of the maxillary anterior region of the mouth. His right central incisor presented subluxation and root fracture, the left central incisor had suffered intrusive luxation and root fracture. The initial treatment involved reposition and fixation of the teeth with 0.5mm stainless steel wire and composite resin. The patient was submitted for clinical and radiographic fallow-up. After 4 years, radiographically the right central incisor seemed to be healed by hard tissue union and showed to be indistinct fracture line, intact lamina dura. The left central incisor radiographically was healed by interposition of bone and connective tissue and showed to be distinct horizontal fracture line separating the fragments, and pulp canal obliteration. In clinical examination, the teeth showed a normal response to elective pulp test, percussion and mobility test. Pulp survival after injuries appears to be dependent upon the type of luxation injury, age of patient, stage of root development and degree of dislocation. In this case, the two teeth with incomplete root formation were suffered different type of injury by trauma and has showed different healing aspect.

• The Journal of the Korean dental association
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• v.13 no.6
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• pp.563-567
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• 1975

This present investigation was concerned with the content of collagen and minerals of incisor and molar dentin in rats of differednt ages. The results obtained were summarized as follows. 1. There was no remarked change in the content of collagen-hydroxyproline of incisor and molar dentin according to days after delivery. 2. The Ca content in incisor dentin rose from approximately 15.4% of the dry weight in 7 days after delivery to 21.1% in 22 days while that in molar dentin from 17.6% in 7 days to 19.7% in 22 days. 3. The P content in molar dentin rose from 8.5% in 7 days after delivery to 11.65% in 22 days. while in incisor rose from 8.05% in 7 days to 11.85 in 22 day after delivery.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.302-322
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• 1998

This study was accompolished to analyze and compare the number and area of the occlusal contact points in healthy volunteers and athletes with normal occlusion. For this study, 15 athletes(13 amles and 2 females with average age 20) and 21 healthy volunteers(14 mles and 7 females with average age 20.09) were selected. The visual display acquired by scanning of occlusal record in maximal intercuspation was converted into 16 gray value image. Then, using computer program(J & Lee Occlusal Analyser), the pixel which was in definite range of the gray value was recognized, and the numbers of recognized pixel were calculated to area. The results were as follows ; 1. The average numbers of total occlusal contact feints were 31.05 in control group, and 34.67 in athlete group. The average area of total occlusal contacts was $100.25mm^2$ in control group, and $127.78mm^2$ in athlete group. 2. In control group, the average numbers of occlusal contact points were revealed in order as follows ; the first molar(8.48), the second molar(8.24), the second premolar(4.71), the lateral incisor(2.90), the first premor(2.43), the central incisor(2.19), and the canine(2.1). The least average in canine(2.1) was similar to the average(2.19) in central incisor and (2.09) in lateral incisor. In athlete group, the average numbers of occlusal contact points were revealed in order as follows ; the first molar(8.97), the second molar(8.47), the second premolar(5.60), the canine(3.80), the lateral incisor(3.33), the first premolar(2.67), and the central incisor(1.93). 3. In control group, the average areas of occlusal contact surface were revealed in order as follows ; the first molar($39.47mm^3$), the second molar($37.54mm^3$), the second premolar($9.54mm^3$) the first premolar($6.18mm^3$), canine($3.49mm^3$), the central incisor($2.76mm^3$), and the lateral incisor($1.28mm^3$). In athlete group, the average areas of occlusal contact surface were revealed in order as follows ; the first molar($44.11mm^3$), the second molar($40.69mm^3$), the second premolar($16.50mm^3$), the first premolar($9.39mm^3$), the canine($5.08mm^3$), the lateral incisor($3.7mm^3$), and the central incisor($2.25mm^3$). 4. With aging in both control and athlete group, there was a decreasing tendancy in average number of occlusal contact point, and was an increasing tendancy in average area of occlusal contact surface. In comparison at each age, both the numbers and area of occlusal contact were greater in athlete group than in control group. It was not significant in the numbers of occlusal contact points beween athlete and control group(p>0.1), but significant in the area of occlusal contact surface(p<0.03). 5. In comparision as to the kind of sports(Gymnastics : 2, Rugby : 3, Soccor : 5, Ice hocky : 5), the numbers of occlusal contact points were the most in ice hocky, and the area of occlusal contact surface was the greatest in gymnastics. With increasing a career in athlete group, there was a decreasing tendancy in average numbers of occlusal contact points and was an increasing tendancy in average area of occlusal contact surface. 6. By T-scan analyzing, the contact numbers on the anterior teeth were greater in control group than in athlete group, and on the posterior teeth were greater in athlete group than in control group. And the results acquired by T-scan were lesser than that caquired by the silicone bite records. It was not significant in the posterior teeth, but significant in the anterior teeth. In T-scan records, the numbers of occlusal contact points on second molar were the greatest, but in the silicone records, the numbers on first molar were the greatest.