• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.205-217
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• 2014

Purpose: This study will examine the differences among the college dental morphology textbooks in light of their contents and learning objectives through which we will propose an optimal way of consolidating those differences found. Methods: Five college textbooks adopted in the dental related departments were selected by random and the overview and subdivisions of contents were compared and closely analysed with regards to the learning objectives. Results: Firstly, all of the dental morphology textbooks cover the learning objectives of the dental morphology subject, especially in the area of the overview of dental morphology, the permanent tooth, deciduous tooth. Only the dentistry textbooks explain the learning objective of the occlusion. Secondly, differences in content were found in the area of component tissue and around tissue, dental formula of deciduous teeth, spinous process, buccal pit, enamel projection, curve symbol, tip of cusp position of proximal surface of permanent mandibular canines, buccal cusp position of permanent mandibular second premolars. Conclusion: It is imperative to delineate some meaningful and critical differences in contents among the dental morphology textbooks and reflect this to each and every textbook to be published as a supplementary information guide or index.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.607-618
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• 1993

If the centric prematurity occurs after orthodontic treatment, it creates centric slide regarded as a possible factor in the cause of temporomandibular disorder and/or postorthodontic relapse. The purpose of this study was to investigate the manner of centric prematurity and centric slide in postorthodantic patients. The 36 orthodontic patients who had been treated with edgewise appliance at least 3 mouths previously were used in this study. After recording centric relation by the leaf gauge technique, the centric prematurity and centric slide were studied using SAM2 articulator and mandibular position indicator. The results were as follows : 1. The highest percentage of centric prematurities were found on the second molars. 2. The buccal incline of the palatal cusp was the most frequent area of centric prematurities in the maxilla, while the lingual incline of the buccal cusp was the most frequent area in the mandible. 3. There were no trends in the direction of centric slide on the mandibular position indicator. 4. There were no significant differences in centric discrepancies between the premolar extraction and nonextraction group.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.217-225
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• 1988

This study was undertaken to examine relationship between tooth size and arch dimension in dental crowding. Two groups of dental casts were selected on the basis of dental crowding. One group, consisting of 51 pairs of dental casts (24 male and 27 female), exhibited remarkable dental crowding. A second group, consisting of 60 pairs of dental casts (30 male and 30 female), exhibited little or no crowding. Mean and standard deviation of the following parameters were used to compare two groups. individual and collective mesiodistal tooth diameters, buccal and lingual arch widths and arch area. The following results were obtained. 1. The crowed group revealed larger tooth size than noncrowded group. (p < 0.01) 2. The crowded group smaller maxillary dental arch dimension than noncrowded group except lingual arch width at canine region. (p < 0.01) 3. The corwded group revealed smaller mandibular dental arch dimension than noncrowded group except lingal arch width at second premalar region in the male and buccal arch width at canine, premolar region in the female. (p < 0.01) 4. The crowded group revealed smaller arch area than noncrowded group in the female (p < 0.01), but there was no significance in the male.

• Animal Systematics, Evolution and Diversity
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• v.24 no.1
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• pp.81-88
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• 2008

Two oxytrichid ciliates collected from the mosses and estuarine littoral in Korea were identified as Oxytricha longigranulosa Berger and Foissner, 1989 and O. marina Kahl, 1932. These species are reported for the first time from Korea. The description was based on living and protargol impregnated specimens. Diagnostic characters for each species are as follows. Oxytricha longigranulosa: Cell in vivo $80-115{\times}30-50{\mu}m$, mostly $90{\times}40{\mu}m$. Length/width ratio about 2.4/1. Cortical granules about $1{\times}1.5{\mu}m$ in size, colorless, arranged in short and discontinued longitudinal rows. Four frontoventral cirri. Adoral zone of membrane lies (AZM) covering 30-50% of cell length with 25-27 adoral membranelles (AM). Buccal area flat, typical Oxytricha pattern. Five transverse cirri, 19-23 right marginal cirri, 19-24 left marginal cirri, three caudal cirri, five dorsal kineties. Two macronuclear nodules 2 in number and spherical in shape, two micronuclei in number. Oxytricha marina: Cell in vivo $100-150{\times}30-60{\mu}m$. Cytoplasm colorless without cortical granules. Four frontoventral cirri. AZM covering 50% of cell length with 28-44 AMs, Buccal area flat, typical Oxytricha pattern. Five transverse cirri, 23-38 right marginal cirri, 19-25 left marginal cirri, three caudal cirri, five dorsal kineties. Two macronuclear nodules and spherical in shape, 1-5 micronuclei, mostly two in number.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.428-446
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• 1997

Restorative procedures can lead to weakening tooth due to reduction and alteration of tooth structure. It is essential to prevent fractures to conserve tooth. The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method and isthmus(1/4, 1/3, 1/2 of intercuspal distance) were varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. 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 follows : 1. Displacement of buccal cusp in R model occurred and increased as widening of the cavity, and displacement in B model was little and not influenced by cavity width. 2. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 3. With the increase of the isthmus width, B model showed no change in the stress and strain. In R model, the stress and strain increased both in the area of buccal-pulpal line angle and the buccal side of marginal ridge, therefore the possibility of crack increased. 4. The stress and strain were distributed evenly on the tooth in B model, but in R model, were concentrated on the buccal side of the distal marginal ridge and buccal-pulpal line angle, therefore the possibility of fracture increased.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.57-64
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• 2018

Pre-eruptive intracoronal resorption (PEIR) is a developmental defect in the crown of a pre-eruptive tooth. The purpose of this study was to investigate the relationship between the size of the pre-eruptive buccal pit radiolucency, which is suspected as PEIR on a panoramic radiography, and the need for restoration after the eruption of a mandibular first molar. The experimental group included 35 mandibular first molars, in which lesions requiring definite restoration were observed during eruption. The control group consisted of 64 sound mandibular first molars after eruption. The sex, age, tooth position, tooth formation stage, size of the pre-eruptive buccal pit radiolucency, and restoration methods in the experimental group and control group were examined. Compared with the control group, the experimental group showed a statistically significant difference in the size of the buccal pit before eruption. The buccal pit size for predicting the need for restoration was further examined by receiver operating characteristic curve analyses, and the area under the curve was $0.813{\pm}0.047$. If radiolucency is observed at the buccal pit of the mandibular first molar before eruption, periodic observations and post-eruption examinations are required.

• The korean journal of orthodontics
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• v.31 no.6 s.89
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• pp.559-566
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• 2001

This study was undertaken to demonstrate the forces in the mandibular alveolar bone generated by activation of the mandibular posterior crossbite appliance in the treatment of buccal crossbite caused by lingual eruption of mandibular second molar. A three-dimensional photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone. We observed the model from the anterior to the posterior view in a circular polariscope and recorded photogtaphically before and after activation of the mandibular posterior crossbite appliance. The following results were obtained : 1. When the traction force was applied on the buccal surface of the mandibular second molar, stress was concentrated at the lingual alveolar crest and root apex area. The axis of rotation also was at the middle third of the buccal toot surface and the root apex, so that uncontrolled tipping and a buccal traction force for the mandibular second molar were developed. 2. When the traction force was applied on the lingual surface of the mandibular second molar more stress was observed as opposed to those situations in which the force application was on the buccal surface. In addition, stress intensity was increased below the loot areas and the axis of rotation of the mandibular second molar was lost. In result, controlled tipping and intrusive tooth movements were developed. 3. When the traction forte was applied on either buccal or lingual surface of the second molar, the color patterns of the anchorage unit were similar to the initial color pattern of that before the force application. So we can use the lingual arch for effective anchorage in correcting the posterior buccal crossbite. As in above mentioned results, we must avoid the rotation and uncontrolled tipping, creating occlusal interference of the malpositioned mandibular second molar when correcting posterior buccal crossbite. For this purpose, we recommend the lingual traction force on the second molar as opposed to the buccal traction.

• The korean journal of orthodontics
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• v.33 no.3 s.98
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• pp.151-156
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• 2003

To provide some guideline for microscrew implants, 73 patients that received a total of 180 mini- or microscrew implants were scrutinized. The overall success rate was $93.3\%$ (168 among 180 mini- or microscrew implants) and the mean period of utilization was 15.8 months. Microscrew implants in the UB group (maxillary buccal area) succeeded at a rate of $94.6\%$ (87 among 92), mini- or microscrew implants in the LB group (mandibular buccal area) succeeded $96.6\%$ of the time (56 out of 58), while microscrew implants in the UP group (maxillary palatal area) had a $100\%$ success rate (11 out of 11), and mini- or microscrew implants in the LR group (retromolar area) succeeded in $73.7\%$ of cases (14 among 19). This study might indicate that microscrew implants can be used successfully as orthodontic anchorage in daily orthodontic practice.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.135-142
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• 1992

This study was performed to define the anatomical position of the mandibular canal and the findings during the sagittal split ramus osteotomy of the mandible. The mandibles of 20 adult Korean were used. The dimension of mandibular canal from the mandibular foramen to the 1st molar was measured at 4 specific coronal-sectional location by CT scan. The results were as follows ; 1. The distance from the mandibular canal to the medial aspect of the buccal cortical plate was greatest($4.5{\pm}1.1mm$) at 2nd molar area and was not significantly greater than at any other section. 2. Buccal cortex was thickest($3.8{\pm}0.9mm$) at 2nd molar and thinnest ($2.5{\pm}0.3mm$) mandibular foramen um 3. The distance from the mandibular canal to the medial aspect of the lingual cortical plate was not significant at any sections. 4. The distance from the mandible canal to the inferior border of mandible was greatest at the mandibular foramen($20.7{\pm}3.9mm$). The canal was located more closely to the inferior border at 1st, 2nd molar area 5. The diameter of the mandibular canal was between $2.5{\pm}0.3mm$ and $2.8{\pm}0.6mm$. 6. The total mandibular thickness was greatest($21.1{\pm}2.6mm$) at 2nd molar area and narrowest($17.2{\pm}3.2mm$) at mandibular foramen area.

• Korean Journal of Cleft Lip And Palate
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• v.4 no.1
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• pp.1-11
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• 2001

Disposable blade is widely used for palatal and oral mucosal incision in oral and maxillofadal surgery nowadays, But its design and durability need for improvement, Especially, there are so many hard tissues intraoral area, such as bone and tooth, therefor the sharpness of the surgical blade was easily destroyed, The purpose of this study was to make basic data for developing new design of surgical blade using in oral and maxillofacial area including for the patients who have cleft lip and palate deformities, Some questionnaires about the usefulness of currently used surgical blades were sent to 150 dentists, the 54 of them made a reply, Secondly, The used-once blade and fresh new blade were examined under the scanning electron microscope with the 4000-times magnification, Lastly, the tissue reaction following the surgical incision with a fresh-new and a used blade on rat buccal cheek mucosa and hard palate was evaluated with light microscope with hematoxilin-eosin staining, The time interval from the surgical trauma to taking a sample were 1 day, 3 days, 7 days, and 14 days, At each time schedule, 2 Sprague-Dawley rats were sacrificed, Many dentists were agreed to need for changing the design of the surgical blades and also demand to improve the durability of the blades, They were also eager to adopt the new design of blade if it was available, The blade used in surgical extraction procedure was heavily damaged in its sharpe edge of number 15 blade, The histological differences were not prominent, but the delayed healing was detected in buccal mucosal defects especially in the surgical group with used blade, There are slight different changes in hard palatal defects between a used and a new blade group, In this study, we could find that there are imperative demanding on improvement of surgical blade design and durability for oral and maxillofadal area, The blade currently using in surgical extraction was easily damaged, The animal model of this study was not perfect for the purpose of this study.