• The Journal of the Korean dental association
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• v.14 no.5
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• pp.461-463
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• 1976

The case of chronic alverolar abscess treated by apicoectomy and intubation technique is reported. The chronic alverolar abscess developed at the apex of the right lower first premolar in the 30-year old Korean female. And the lesion involved the root of the adjacent second premolar.

• The korean journal of orthodontics
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• v.37 no.6
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• pp.407-420
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• 2007

The aim of this study was to compare the differences in closing extraction spaces between maxillary first premolar and second premolar extractions using 3-dimensional finite element analysis (FEA). Methods: Maxillary artificial teeth were selected according to Wheeler's dental anatomy. The size and shape of each tooth, bracket and archwire were made from captured real images by a 3D laser scanner and FEA was performed with a 10-noded tetrahedron. A $10^{\circ}$ gable bend was placed behind the bull loop on a $0.017"{\times}0.025"$ archwire. The extraction space was then closed through 12 repeated activating processes for each 2mm of space. Results and Conclusions: The study demonstrated that the retraction of anterior teeth was less for the second premolar extraction than for the first premolar extraction. The anterior teeth showed a controlled tipping movement with slight extrusion, and the posterior teeth showed a mesial-in rotational movement. For the second premolar extraction, buccal movement of posterior teeth was highly increased.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.227-234
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• 1990

The purpose of this study was to evaluate the incidence and several radiographic features of dilacerated teeth in 2132 full month radiograms in Korean. The results were as follows: 1. The occurrence was revealed to 2.7% in total examined teeth, and these anomalies were occurred in maxilla (52.4%) more than in mandible (47.6%). 2. There was a predilection for occurrence of dilaceration in female, which included 12.8% of the female compared to 11.3% in male. 3. The frequency of dilaceration in male, which included 40.5% in maxilla and 59.5% in mandible. The frequency of dilaceration in female, which included 52.4% in maxilla and 47.6% in mandible. 4. The order of frequency of dilaceration was second premolar, first premolar, lateral incisor, canine in maxilla, and first premolar, second premolar, canine, lateral incisor, central incisor in mandible. 5. In classifying of dilacerated teeth into 3 types by following appearances such as root curvature. Distal dilaceration was by far most common containing 65.8% of the cases. The least frequent was mesial dilaceration, which included 6.5% of the cases.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.473-482
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• 2012

Purpose: The purpose of this study was to investigate the stress distribution of the surrounding tissues according to 3 proximal plate types of the RPI clasp. Methods: The removeable partial denture which mandibular right and left second premolars and mandibular molars were lost was attached to a three dimensional photo elastic epoxy resin model. Then 120N of vertical load was applied. After 3-dimensional photoelastic stress analysis was used to record the isochromatic fringe patterns. Results: Kratochvil type guiding plane exhibited little uniform stress distribution on load center and alveolar ridge, but higher stress concentration on buccal surface of second premolar. Krol type guiding plane exhibited the stress concentration on the front of load center and relatively higher stress concentration on buccal surface of first premolar. However, this type had no effect on canine. Researcher type guiding plane showed the stress concentration on second premolar and molar, but the little stress distribution on first premolar. Conclusion: In all types, excessive stress concentration was appeared and three types were not significant different.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.10 no.1
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• pp.41-46
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• 1980

The mandibular canal must be considered carefully during the surgical treatment, especially surgical extraction of the impacted tooth and intraosseous implant, because it contains the important inferior alveolar nerve and vessels. The author investigated the curvature of the mandibular canal and its relation to the mandibular molars and positional realtion between the mental foramen and the mandibular premelors in orthopantomogram. The materials consisted of 441 orthopantomograms divided four groups; Group Ⅰ consisted of 56 males and 44 females from 1 to 6 years of age, Group Ⅱ consisted of 58 males and 45 females from 7 to 12 years of age, Group Ⅲ consisted of 65 males and 33 females from 13 to 18 years of age, Group Ⅳ consisted of 86 males and 54 females over 19 years of age. The results were as followings; 1. The curvature of mandibular canal was 144.50° in Group Ⅰ, 144. 29° in Group Ⅱ, 148.11° in Group Ⅲ, 147.33° in Group Ⅳ. 2. The curvature of mandibular canal was located most frequently on the area between mandibular 1st molar and mandibular 2nd molar in Group Ⅰ (42%) and on the mandibular 2nd molar area in Group Ⅱ (54%), Group Ⅲ (59%), Group Ⅳ (53%). 3. The position of mental foramen was most frequently below the mandibular 1st premolar in Group Ⅰ (58%), between the mandibular 1st premolar and the 2nd premolar in Group Ⅱ (62%), Group Ⅲ (47%), and below the mandibular 2nd premolar in Group Ⅳ (58%).

• Journal of Oral Medicine and Pain
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• v.18 no.1
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• pp.107-117
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• 1993

The author has taken intraoral standard films by the paralleling technique of 6414 teeth in 838 patients ranged from early twenties to early sixties and analysed the change of pulp cavity in the mandibular posterior teeth by ageing. The obtined results were as follows : 1. There was no significant difference between the right and left teeth. 2. The degree of change of pulp cavity in female was higher than that in male. 3. The change of pulp cavity was increased by ageing. 4. The correlation between the degree of change of pulp cavity inmandibular posterior teeth (X) and age (Y) were : Male 1st premolar Y=13.22X3.37+ r=0.79 2nd premolar Y=12.09X+3.65 r=0.79 1st molar Y=11.90X+1.25 r=0.78 2nd molar Y=10.51X+10.43 r=0.83 Female 1st premolar Y=13.66X-2.49 r=0.86 2nd premolar Y=13.63X-2.42 r=0.86 1st molar Y=12.42X-1.44 r=0.79 2nd molar Y=11.42X+5.91 r=0.84

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.65-78
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• 1988

The development of good arch form, the orientation of the dentition with relation to the craniofacial skeleton and the establishment of correct relationship of axial inclination of upper and lower teeth are required in normal occlusion, but different teeth present different degrees of axial inclination. The purpose of this study was to investigate the axial inclination of upper and lower teeth by analyzing $45^{\circ}$ oblique and $90^{\circ}$ cephalometric roentgenograms of 35 Korean males and 34 females with normal occlusion. The obtained results were as follows: 1. Mean and standard deviation of mesiodistal axial inclination of upper and lower teeth related to palatal plane and occlusal plane were obtained. 2. Mesiodistal axial inclination of upper first premolar was nearly perpendicular to palatal plane, and the axis of lower first premolar was nearly perpendicular to occlusal plane. 3. There was no difference in the mesiodistal axial inclination of anteriorly positioned teeth between the three groups: third molar eruption into good alignment (Group 1), third molar impaction or partial eruption (Group 2), third molar agenesis (Group 3). 4. There were low correlationships only between the axial inclination of central incisor and the mesiodistal axial inclination of canine and first premolar, but no correlationships between central incisor and posterior teeth behind first premolar.

• Imaging Science in Dentistry
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• v.40 no.3
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• pp.131-135
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• 2010

Purpose : The aim of this study was to investigate the timing and sequence of eruption of permanent canine and premolars, and to evaluate tooth calcification stage on emergence in Korean children. Materials and Methods : The sample was comprised of 1,266 children (male 720, female 546) aged from 7-13 years. Tooth eruption and calcification stages were determined through oral and panoramic radiographic examination, respectively. Probit analysis was used to calculate the timing of tooth eruption and tooth calcification stage from these cross-sectional data. Results : In both males and females, eruption occurred around the time when one third of tooth root or more was formed. The sequence was as follows: first premolar, canine, and second premolar in maxilla, and canine, first premolar and second premolar in mandible. Tooth eruption occurred earlier in girls compared with boys, averaging 0.63 years. Conclusions : Eruption sequence is identical in males and females with a trend for females to erupt earlier than males. Tooth eruption becomes earlier over the past decades in Korean children.

• The korean journal of orthodontics
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• v.32 no.3 s.92
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• pp.185-194
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• 2002

When treating borderline cases which have mild crowding, non-extraction treatment may be considered firstly. But crowding may be reappeared by relapse and it may have problems in esthetics and stability. Secondarily four first premolar extraction treatment may be considered. But this may cause dish-in face by overretracting anterior teeth. In this cases, extraction of four second premolar is preferred because this resolves crowding without aggravating profile and has good stability after treatment. So we review cases treated by four second premolar extraction which show good treatment results and stability. The patients had good profile, Class I molar relationship, mild crowding and skeletal discrepancy and their growth had almost completed.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.180-189
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• 2015

Objective: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. Methods: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. Results: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. Conclusions: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.